Marjorie M.Sweeting, Oxford
School of Geography, Oxford University, England

The karstlands of S. E. Europe and of Southern China form the two largest and most varied areas of karst relief in the world. This contribution attempts to compare the development of the ideas of karst geomorphology in these two regions. Because of differing geological and geographical conditions, the emphases and explanations of karst phenomena have developed along quite different lines. Furthermore, Chinese attitudes to land use have led to a greater exploitation of karst areas than in Europe.

Because of the situation of Southern China within the S.E.Asian monsoon area, the Chinese karstlands are much more dissected by the great rivers and are more fluvio-karstic than the karstlands of Southern Europe. Karst studies in China have been much more integrated into general Chinese karst geomorphology than in Europe. Debates about karst water-levels and base-levels which formed a conspicuous part in the development of karst thinking in Europe, have been absent in China. Both regions have been subjected to neotectonism, but the proximity of the Chinese karst areas to Tibet and the Himalayas is probably of greater significance than the nearness of the classical karst and Dalmatia to the Alps. The Quaternary history of the two regions is quite different and is reflected in the legacy of the Quaternary period upon the landscapes. Chinese geomorphology has been less affected by debates about the importance of climatic geomorphology than in Europe. The opening up of the karstlands of China, together with the vast amount of work now being done by Chinese scientists, can lead to a useful reappraisal of the ideas and development of karst geomorphology in Europe and also in America.

Kohler, Heinz-Charles¹, Auler, Augusto², Catta nio, Mariab^3
1 Museu de Historia Natural, Federal University of Minas Ger ais, B razil
² Geography and Geology Department, Western kentucky Un iversity, USA
³ Federal University of Mato Grosso do sul, Brazil

The area is located in the eastern border of Brazilian Pantanal, 200 km away from Campo Grande, capital of Mato Grosso do Sul State. The karst occurs in folded and faulted calcitic and dolomitic limestone belonging to both Cuiaba and Corumba Formations of Upper Paleozoic age. The karst landforms develop in Serra d a Bodoquena(Bodoquena Hills) anticlinal and at Salobro and Formoso Rivers sincli nal, as a 100 km long stripe running norh-south.

Karst morphology is characterized by four distinct physiographical domains:A) Fluviokarst of Perdido River basin, developed in the high level karst plains, at an average altitude of 600m; B) Isolated hills 100 m high in average containing both solution and collapse sinkholes representing a residual form of domain A; C) Karst plain (at a 320 m topographical level) containing the rise of most of the rivers. Two types of springs can be distinguished, a diffuse discharge spring and a conduit flow spring; D) Fluviokarst of Formoso and Prata Rivers showing travertine deposition.

The underground karst is well developed throughout the area. The caves contain usually large descending passages that intercept the water table. Cave diving performed by the second author has shown that some underground lakes exceed 50 m in depth. The lake at Lago Azul cave show a very peculiar troglobitic fauna not found in other lakes. A slow movement of water was detected in this cave in contrast with the static water at other sites such as Anhumas Pit. The water level at Lago Azul cave lies 15 m below the regional base level measured at nearby rivers, suggesting a complex hydrogeological pattern. Cave cones up to 10 m high were located in caves with no air space. This speleothem is formed through accumulation of cave rafts. This data points toward a lower paleo water level in the caves. Stalactites found under 20 m deep water represent further evidence of a slow subsidence of the area.

Ford, Derek C.
Department of Geography, McMaster University, Ontario, Canada

Limestone, dolomite, gypsum and anhydrite outcrop over 1,200,000 square kilometres in Canada and there are more than 500,000 square kilometres of salt accessible to interstratal dissolution. Most of the country was repeatedly glaciated by alpine glaciers or continental ice sheets during the Quaternary; half of it is permafrozen today.

The interrelationships between glaciers and components of the karst system are complex and varied. Nine differing effects of glacier action upon karst are recognised here: 1. erasure by glacier scour, impacting chiefly upon karren; 2.dissection of cave systems, principally in alpine areas; 3. infilling of dolines and poljes with glacial detritus; 4. injection of detritus deep into the aquifer, rendering it partly or wholly inert; 5.shielding of soluble bedrocks from postglacial dissolution by detritus rich in soluble fragments; 6.sealing of limestone and dolomite pavements by melt-out tills; 7.acceleration of karst development by superimposing glacier aquifers upon karstic aquifers; 8.steepening groundwater hydraulic gradients by glacial entrenchment of valleys; 9.inducing interstratal dissolution by deep injection of groundwaters during glacial recession and isostatic rebound.

Relationships with modern permafrost are also complex. Glacieres (ice-filled caves) exist S. of permafrost boundaries. There is little impediment to karstic groundwater circulation in the discontinuous permafrost zone. Where permafrost is widespread or continuous, active karst progressively shrinks to the zones of highest hydraulic gradient or most soluble rocks. At the climatic extreme karst is of subglacial melt origin and is relict in postglacial environments.

Rai, R.K.
Department of Geography, North-Eastern Hill University, Shillong, India.

The Cherrapunji Plateau is the part of Meghalaya, geologically and physi ographically the Meghalaya Plateau is a part of Peninsular Shield located to the south of the north-eastern segment of the Himalayas.

The development of karst geomorphological landscapes in the vast karst regions of Meghalaya is closely related to lithological characteristics of rocks and is controlled by many natural conditions in particular lithology, structure of rocks, climate, height of the water table and nature of drainage as well as biogenic process. The southern part of the plateau is mainly composed of Cretaceous Tertiary sedimentary rocks and a narrow belt of Sylhet Traps. Numerous faults and folds are traced in the rocks. The uplift of the plateau in different periods has given rise to a complex multi cyclic landscape. In the region the structural events in later part of Tertiary period and climatic changes have interacted to influence and control karst development. The development of Mawsmai cave reflects the control of lithology and structure. The limestone deposits found in Cherrapunji plateau consists of limestone, sandstone, shale and thin bends of coal. The caves with stalactites and stalagmites, sinkholes, underground channels are the common features in the area.

Ngo Ngoc Cat, Eng. Le Uxuan Hong
NCSR of Vietnam

Investigations on subsurfacial karstic development of karstic plains see m to be extremely important not only in theoretic side but also in practical side, especially for groundwater prospecting and investigations, construction of irrigation system (hydro-electric dam, water reservoir), basements, bridges and other industrial and military establishments.

Based on the multiannual investigation results on hydrogeology and engineering-geology conducted by Geological Inspecting Teams No.9T, 58, 63, 47 and 37 at different area of Northern Vietnam and the field investigation of the Authors at Thainguyen, Honggai, Phuly, Ninhbinh and Thanhhoa, the following conclusion can be proposed:

1. Subsurfacial karstic development is available in the two main d irections of NW-SE and NE-SW .
2. Karstification is being diminshed with the depth of 60-70 m. The most popular depth of subsurfacial karstic groundwater      bearing caverns is 10-40 metres.
3. The linear coefficient of Karstification is mainly in the range of 10 -15%.
4. It is the groundwater that has decisive role in subsurfacial karstifica tion velocity.
5. The above mentioned conclusions more or less correspond with the subsur face
    geophysical investigation results from electric-sounding and well-logging approaches.

E.Raeissi
Department of Geology, Shiraz University, Iran

DISTRIBUTION MAP OF LIMESTONE AND DOLOMITE IN IRAN

IV₂ MECHANISM OF KARST FORMATION

CAVE FORMATIONS OF THE AEROSOL ORIGIN

A.B.Klimchouk, V.M.Nasedkin, K.I.Cunningham

Secondary cave formations of the aerosol origin. Peculiarities of morphology, structure and localization of some types of gypsum secondary formations (crystals, rims, hollow "stalactites") are considered from caves of the Western Ukraine, Kugitang Ridge(Turkmenistan) and Guadalupe Mountains (USA). It is shown that all these formations are controlled by air flow and caused by deposition from aerosols. Mechanisms of generation of cave (autochtonous) aerosols are suggested. Enhanced radioactivity and high ionization of cave air are major prerequisites for cave aerosol formation. As a result of radioactive decay condensation aerosols, aeroions of mineral combinations and solid aerosols are formed. Mechanisms of transportation and deposition of aerosol material in forms of above formations are considered. It is assumed that many cave subaerial formations are of an aerosol origin.

Guizho Science Fund sponsored project
An Yuguo¹ He Fusheng ² Rong Kunf ang ³ Li Jingyang ^3
1 Guizhou Academy of Science
²Guizhou Normal University
³Guizhou Institute of Technology

Through detail investigation of stromatolites of speleothems in Zhijin Cave, Guizhou, the author has systematically collected samples of live algae and speleothem. The species of live algae are identified by biomicroscope, petrographic microscope and SEM observation: preliminary ascertainment of species related to lithogenesis and bilateral comparison with algae fossil in stromatolite, we have determined that algae fossil in stromatolite is similar to live blue-green algae which belongs to the Quaternary fossil of blue-green algae. Finally, structural characteristics of stromatolite has been assorted.

Keywords: Zhijin Cave, Stromatolite of Speleothem, Organic Build Up

1. The stratum that the cave develops is Huangchu Ba member, Yuelang group, lower Triassic period (T₁Y²), which is composed of thin to thick bedded bright pale limestone. Its total thickness is 210 m. The overlying stratum, Juoji tan member(T₁Y³), is purple shale which is 54 m thick. The underlying stratum, Shabaowang member(T₁Y¹), is yellow green shale 34.5m thick.

2. The cave situation: 1316 m a.s.l. at cave gate; 1391 m a.s.l. at Shiwan Dashan, the highest bottom in the cave; 1132 m a.s.l. at Shuixiang Zeguo, the lowest part in the cave. The relative elevation is 249 m. According to U-series dat ing, the oldest formation of the speleothem is 261thousand year s B.P(Zhao Sushen,1989).

The gate of Zhijin Cave is facing southwest 240°E . Longer time sunshine, air, humidity and temperature is suitable for algae living. Therefore, algae are prospering in the Yinbing Hall, especially for blue-green algae species. On the surface or wall of collapsed rock and the cave, "algae crust", constructed by kinds of live algae colony is growing. It has been identified that include: Gl oeocapsa Kutz., Nastoc Vanch., Chroococcus Nag., Phormidium Kutz, etc, all of which in Cyanobyta. Example 1: on a collapsed boulder's surface a solidified white speleothem stripe has been formed along the surface due to weeping effect; a "algae crust" cap, 0.5-2.0 mm thick, is growing on its surface (Fig.I-1). It is observed to be live blue-green algae colony that we have mentioned (Fig.I-2). Example 2. On another nodular stalactite (diameter 5-25 mm), a layer of purple, blue and green algae crust cap is growing on the surface, and CaCO₃ powder like speleothem saturated with water and cream white color can be seen after removing the crust on the nodule. Downwards, on the base, there are solidified and striped nodular speleothem(Fig.I-4). Example 3: On a northwest fault wall, similar nodule are growing parallely, covered by a green algae crust which is also formed by the above mentioned live algae colony after observing it from SEM(Fig.I-5).

Fig.1 The Sketch Map of Z hijin Cave
W .cave entrance 1.yinbing hall 2.karst window 3.jian menguan 4.caizhulou 5.jinta palace 6.sun & moon lake 7.shouxing palace 8.wa nshou hill 9.wangshanhu 10.mangu corridor 11.nantianmen 12 .xuexang palace 13.linxiao palace 14.guanghan palace 15.yinyu palace 16.shiw an dashan 17.shuxiang zeguo 18.dining hall 19.beihai long
20.dahai long 21.jinshu palace

Many scholars have done detail researches about distribution of blue-green algae colony. Many articles have pointed out that, in bright illuminated shallows, at dark or faint light circumstances, or even in condition of total darkness, blue-green algae can also survive. Therefore, at dim or light scattering places or tourist lamp spotting places, algae is growing at most places. After sampling it is identified to be: Lyngbya Ag., Phormidium Kutz., Scytonema Ag., Tolypothrix Kutz. of Cyanobyta. An extreme flimsy algae crust formed by algae colonies is observed under biomicroscope. Blue-green algae filament excretes calcic material, catchs and adheres tiny particles. This distinct calcification has proved that algae can seek life activity tenaciously in speleothem environment of Zhijin Cave and are primary lithogenesis.

Refering to some related articles (Reference Materials of southwest Geological Technology, 9th volume stromatolite Collection, 1975.Southwest Geological Technology Research Institute .)  and combining them with the st ructural characteristics of stromatolite of speleothem in Zhijin Cave, we have following assortment:

1. Tree stromatolite, depict the speleothem "Yingyu su" in Yingyu Palace(Fig.I-6), "Ta song"(Fig.I-7) and "Xue song"(Fig.I-8) in Jinta Palace as examples. We have found that they belong to "Huge Complex Merged Stromatolite", 7-20 m high, base diameter 0.6-3 m, conic helicoid(dextral), ordered growing schistose str ucture around the trunk. The center of schistose structure is circle or ellipse. Beside the center, laminae are steep arc-ridge and clear, 1-3 mm wide dark stripe, 1.5-2 mm wide bright stripe. They are sheaf and grain calcite. By identification and comparison of algae fossil sections of "Yingyu su"(Fig.II-1), "Ta song"(Fig.II-2) and "Xue song"(Fig.II-3) through petrographic microscope they are found similar to cave live blue-green algae: Lyngbya Ag. and Phormidium Kutz.

2. Slate stromatolite, depict the slaty stalacite at Jianmenguan as example (Fig.II-4). They also belong to "Huge Complex Merged Stromatolite", columnar stromatolite combination in microcosm(Fig.II-5), tabular stromatolite aggregate in macrocosm. The center is ellipse and one or two sides of it are steep arc-ridge lamination which is clear, 0.1-0.5mm wide dark stripe, 0.1-1 mm wide bright stripe, belongs to hoar sheaf calcite.

3.Scale stromatolite, depict the scaly stromatolite at Yinbin Hall and Jinta Palace as examples (Fig.II-6). The scales always are regularly destributed scalelets. The algae lamination is distinct and ripply, 0.1 mm wide dark stripe, 1 mm wide bright stripe, belongs to sheaf calcite crystal.

4.Arch stromatolite, depict the speleothem "Bamankui" at Lingxiao Palace as example(Fig.II-7). They are "Huge Complex Merged Stromatolite". Its cross section is concentric arch structure. And its lamination is distinct and beded or ripply, 0.1-1 mm wide dark stripe, 0.1-1 mm wide bright stripe, belongs to sheaf calcite crystal.

5.Column stromatolite, depict with the white deposition (Fig.II-8) at Wansanhu and stoneflower at Mangu Corridor. Regular or irregular, furcated or unfurcated(Fig.III-1) cross section is concentric columnar lamination (Fig.III-2,3). The lamination is compact, distinct and ripple arched, 0.16 mm wide dark stripe, 0.17 mm wide bright stripe, are grain calcites most of them. The identification and comparison of algae fossil section through SEM have discovered blue-green algae fossil which are similar to live blue-green algae: Lyngbya Ag., Phormidium Kutz(Fig.III-4).

6. Nodule stromatolite, depict with the nodular stalactite (Fig.I-4) at Yinbin Hall and Jianmenguan as examples (Fig.III-5). The center is stellar half sphere nodular structure that expands around and protruds upwards. It has distinct lamination, 0.1-1.62mm wide dark stripe, 1.39 mm bright stripe and it is c olumnar calcite crystal. The identification of algae fossil by SEM has shown blu e-green algae fossils that are similar to live algae: Gloeocapsa Kutz., Nostoc Vauch., Chroococcus Nag., Phormidium Kutz. (Fig.III-6)

7. Globe stromatolite, depict the "cavepearl" at Chaizulou as example (Fig.III-7). They are globular or elliptical, ordinarily 15-50 mm in diameter, mostly have one core that are mainly constituted by crumbs and gravels. The lamina is concentric, compact and distinct, 0.1-1 mm dark stripe, the same wide bright stripe. The identification and comparison of algae fossil by petrographic microscope have found that they are similar to live blue-green algae: Phormidium Kutz.

1. The intrinsic reason of forming grotesque speleothem is lithogenesis that takes major part in the blue-green algae's life activity seeking in cave speleothem.

2. The structures of live blue-green algae colony: algae crust and stromatolite of speleothems are basically the same, from observing by biomicroscope, petrographic microscope and SEM. By comparison algae fossil in stromatolite is found similar to the Quaternary blue-green algae fossil.

3. The structure, shape and characteristics of stromatolite are directly controled by related algae activities.

(1) John I.Wray, 1977, Calcareous Algae. Elsevier Scientific Publishing Company. Amsterdam-Oxford-New York.
(2) Fossil Algae. Recent Results and Developments. Edited by Erik Flugel. Springer-Verlag, Berlin-Heidelberg-New York,       1977.
(3) Zhao Susheng, 1989,U-series Ages of Karst Speleothem in East China. Karst of China. No.1
(4) Rong Kunfang et al. 1991, Organic Build-up of Dripstone deposition in Zhijin Cave. Journal of Guizhou Institute of    
     Technology, No.3

I-1. white speleothem formed by primary lithogenesis, being cov ered by an"algae crust" at Yingbin Hall. photo
I-2. SEM image of I-1. ´EÀ 2000
I-3. SEM image of I-1. ´EÀ 350
I-4. nodular stalactite being covered by an "algae crust" at Yingbin Hall. photo
I-5. SEM image of I-4. ´EÀ 300
I-6. tree stromatolite "Yinyu su" at Yinyu Palace. photo
I-7. tree stromatolite "Ta song" at Jinta Palace. photo
I-8. tree stromatolite "Xue song" at Jinta Palace. photo
II-1. blue-green algae fossil of "Yinyu su" thin section, orthogon al petrography. ´EÀ 65
II-2. blue-green algae fossil of "Ta song", thin section, orthogon al petrography. ´EÀ 65
II-3. blue-green algae fossil of "Xue song", thin section, orthogonal petrography. ´EÀ 65
II-4. thin section of tabular stromatolite sample at Jianmenguan. photo
II-5. columnar lamination in the tabular stromatolite, orthogonal petrography.
II-6. scaly stromatolite on the collapsed boulder. photo of II-7
II-7. "Bawankui" the arch stromatolite at Linxiao Palace. photo
II-8. white speleothem at Wansanhu. photo
III-1. bud furcation of columnar stromatolite in white speleothem at Wansanhu orthogonal petrography. ´EÀ 65
III-2. Cross section of columnar stromatolite in white speleothem at Wansanhu, thin section. photo. ´EÀ 1
III-3. vertical section of columnar stromatolite in white speleothem at Wansanhu, thin section. photo. ´EÀ 1
III-4. blue-green algae fossil in the columnar stromatolite at Wansan hu. SEM image. ´EÀ 200
III-5. vertical section of nodular stromatolite at Jianmenguan. thin section photo. ´EÀ 1
III-6. blue-green algae fossil in the nodular stromatolite at Yingbin Hall. SEM image. ´EÀ 300
III-7. "cavepearl", the globular stromatolite at Chaizulou. photo
III-8. blue-green algae fossil in the globular stromatolite. orthogona l petrography. ´EÀ 65

Geurts, Marie-Anne
Department of Geography, University of Ottawa, Canada

This research examines a growing model of the Holocene travertine deposits of Coal River Springs Ecological Reserve, in southeast Yukon Territory (Canada). This is an answer to a question addressed in the international literature and related to travertine dams and terraces.

The study is based on a systematic analysis of forms observed and measured along the site. It appears that there is a continuum from one type of form to another. The irregularities of the surface trap moss and algae that produce the first filter for clastic and ionic content of the saturated water. The deposition and precipitation of calcite produce the first rims and rimstone pools. The development of rimstone pools induces the formation of corbelling and cerebroid forms in relation with the water movement and degassing. The growth of the rimstone produce dams that become rather thin for their height; these dams are named phytoherms. These phytoherms are made by coalescent inversed inversed corbelling. This structure is due to the association of two mosses: Cratoneuron sp. and Bryum sp.. Discontinuous growth has been observed and tentatively interpreted as hydrological variation and ecological readjustment. They produce cementation of the dams be fore a new stage of building. It appears that downstream dams do not start growing before those upstream get filed with water and start to overflow.

M.j.Buck H.P.Schwarcz,
Department of Geology, McMaster University, Canada

Caves formed by the oxidation of H₂S are being described in an ever in creasing number of localities worldwide. Common to all such caves is the oxidation of H₂S to sulphuric acid. The sulphuric acid reacts with carbonate, frequently p recipitating gypsum in a variety of distinctive deposits. These deposits are key to understanding the mechanisms of formation in both active as well as in relict H₂S caves. Their isotope geochemistry demonstrates the involvement of H₂S.

Comparison of two active H₂S caves clearly shows strong similarities in their hydrogeology, geomorphology and gypsum deposits. Both are vadose and contain thermal water springs which rapidly degas H₂S into the cave atmospheres. At Kan e Caves, Wyoming, U.S.A., Egemeier (1978) described the process of "replacement-solution" whereby carbonate on the walls and ceiling is continuously replaced by gypsum to form a replacement crust. This gypsum crust falls in small fragments and dissolves in the stream on the cave floor. This process enlarges the cave upward and outward. This can also be seen in Villa Luz Cave, Tabasco, Mexico. In both cases, the cave streams have low gradients and are spread over flat floors demonstrating that direct carbonate dissolution by these streams does not significantly contribute to cave enlargement.

Relict H₂S caves are best known in the Guadalupe Mountains, New Mexico, U.S.A.. These include the celebrated Carlsbad Cavern and Lechuguilla Cave, with a combined length of over 130 km. None of these caves have active H₂S springs, but their genesis can be deduced from the nature and isotope geochemistry of extensive gypsum deposits. These deposits are subdivided into three genetic types.

Wolfgang Dreybrodt
Institute of Experimental Physics, University of Bremen, Germany

Karstification is initiated, where a percolating pathway of linked fract ures of about 10^-2cm aperture widths connects a site of water input to an out let, located below the input. Under natural conditions the hydraulic gradients driving water through the fractures are low (i < 0.01) and karstification resulting in tubes of a few mm diameter, takes at least several ten thousands of years.

Close to hydraulic structures, such as dams, vadose cave located below the flow of water reservoirs, or caves where the outlets are blocked for water storage, unnaturally steep hydraulic gradients arise. This can lead to enhanced karstification causing significant leakage in times of only several 10 years, and also might endanger the structural integrity of the bedrock foundation.

To model the development of karst channels in such situations a computer simulation is performed, using the dissolution rates of natural limestone, as derived from laboratory experiments on a variety of rock samples. The results show that initially a slow increase of water flow through the fractures is established until after times of seve ral ten years an extremely rapid increase is observed. After this event of breakthrough the widths of the channels widen rapidly with rates of up to about 10^-1cm/year.

Using this model we discuss the dependence of breakthrough times on the initial parameters. These are the aperture widths of the fractures, the length of the percolating pathway, the hydraulic head which drives the water flow and also the chemical parameters of the solution, mainly the initial P_CO2 in equil ibrium with the water which enters into the fractures, and also the initial concentration of calcium carbonate. We further investigate the influence of grouting to prevent formation of leakage channels.

In summary we show that leakage of hydraulic structures might likely result from solutional widening of preexisting initial fractures, and not only, as usually assumed, from failure of sediment plugs, in preexisting karst channels.

Zhang Jie ¹, Li Shengfeng ¹, Chen Shufan ^2
1 Department of Geo & Ocean Sciences, Nanjing University, Ch ina
²Nanjing College of Education, China

The limestone Sculptures of Liang Dynasty Tomb are located in the east suburb of Nanjing, and have been exposed to subaerial weathering since they were built in AD 522-526. Until they were remounted onto limestone platforms from a rice field several years ago, some had been buried to half of their height by unknown earth accumulation (may be eolian versus fluvial deposition). Microorganisms observed on surface of the sculptures are endo- and epilithic blue-green algae and green algae as well as crustose lichen, which play important roles in surface weathering of the sculpture. Bio-erosional (solutional) phenomena on surfaces include: A) minor honeycomb pit (1.5-2 mm deep) along suture lines with algae covering; B) pin-prick and micro-grooves formed by lichen; C) honeycomb pit patches with algae covering which can only be observed with lens; D) boreholes formed by algal cell or/and fungi filament. With microscopic observation, some interesting mechanisms of bioerosion can be identified. Beside direct erosional effects algae covered with mucus can cause weathering related to the tension developed by drying mucus. Bio-effects combined with other erosional agents causes obvious damage to the sculpture. Bioerosion along suture lines may cause disintegration of the sculptures.

V.S.Kovalevsky, A.V.Efremenko
Water Problems Institute, Russian Academy of Sciences, Moscow, R ussia

As known, karst water regime and resources are defined by the peculiari ty of the geological structure of a territory, climatic conditions, the type and stages of karst development, the degree of relief dissection, landscape conditions and also by the economic activity. The revealing of variations of manifestations of these factors in the karst water regime and resources permits us not only to understand the peculiarities of karst formation in various natural conditions, but also to predict and even quantitatively estimate probable changes in karst water regime and resources, including those under influence of probable transformations of the climate. Such estimations are especially important in regions where karst waters are the main source of public water supply.

We shall examine these peculiarities in three characteristic regions of the Russian platform - the southern coast of the Crimea, Izhorskoe plateau in the B altic area and Ufimskoe Plateau of the West Ural region. The detailed description of the karst of these regions has been given in numerous monographs (Kruber, 1915; Dublyanskii and Kiknadze, 1984; Maksimovich, 1969; Gvozdetsky, 1954; Sokolov, 1962; Gorbunova, 1977, and others). We shall note only the most characteristic peculiarities of these territories, determining the specific of karst formation and, first of all, of karst water regime and resources formation.

The karst of the Mountainous Crimea can be referred to as the karst of the Mediterranean type /2, 9/. This is mountainous, open (from land surface) karst, developing in a region with a strongly dissected relief, up to 1000-1500 m above sea level, in monoclinically occurring (with beds dipping from the south to the north) organogenic limestones of the Upper Cretaceous age with a thickness of 70-80 m. Climatically the area is related to a semiarid subtropical zone where precipitation in the mountainous part reaches 800-1400 mm per year and in the piedmont part it is about 400 mm per year. The precipitation occurs mainly during the cold period of a year and its amount during summer is minimal. The evaporation is about 500 mm per year, the evaporativity is 900 mm per year, annual average surface flow is 300 mm per year, although in upper parts of some karst rivers it reaches 1200 mm per year. The recharge of karst ground water is mainly effected by inflow of precipitation (rain and, in a lesser degree, melted water) during the winter-spring period what determines the characteristic regime of spring discharges and rivers, formed by them /4, 5/.

The karst of Izhorskoe plateau is referred to as the karst of the platform type, where Ordovician limestones are deposited practically horizontally (with a slight inclination to the south), with a thickness of up to 50 m, with a relatively slightly dissected relief, up to 100-150 m above sea level and with an erosional downcutting of up to 50-70 m. On the surface, karstified rocks are overlapped by Quaternary glacial formations of various thickness (from 0 to 30 m), which are represented mainly by loamy moraine with sands, pebbles, and boulders lenses/2/. Climatically, the area is related to a humid coastal zone with a total average long-term amount of precipitation of approximatily 700 mm per year; evaporation is approximatily 450 mm per year, evaporativity is nearly 600 mm per year and surface runoff is nearly 250 mm per year. The precipitation occurs mainly during the warm summer period. However, due to the unstable winter freezing of the zone of aeration the most favourable conditions for ground water recharge are in autumn-winter and spring periods here. The predominant form of karst water recharge is infiltration due to the presence of covering deposits.

The karst of Ufimskoe plateau is also referred to as the karst of the plat form type. Karstified limestones, salts and gypsums of Early Permian age are deposited practically horizontally. Karstified massifs are confined more often to vaults and local rises, brachy-anticlines, are often overlapped by Upper Jurassic and Quaternary terrigenic deposits. The relief is moderately dissected, with absolute elevations of up to 200-250 m and an erosional downcutting of up to 100 m /3, 6, 8/. Climatically the area is related to a moderately continental climate with cold winters, stable freezing of the zone of aeration. The precipitation occurs mainly during the cold period of the year, accumulates in the form of snow and infiltrates during the spring period and during the period of autumn rains. The average long-term amount of precipitation is 700 mm per year, evaporation is 450 mm per year, evaporativity is 600 mm per year. Surface runoff is about 250 mm per year, changing from 100 to 600 mm per year. In spite of a great number of sinkholes (up to 100-500 per sq km) on the surface, ponors and even karren, the predominent type of recharge of karst waters is infiltration that determines the comparative regulation of karst water regime. The karst water regime is various, depending on peculiarities of hydrogeological and climatic conditions. By the time and conditions of recharge it is essentially zonal. In the northern part of the Russian Platform with a stable winter snow cover and the freezing of soils and the zone of aeration, the main recharge of karst aquifers occurs during the spring period. The rise of karst water levels begins with passing of temperatures through zero Centigrade sometimes 2-3 weeks earlier; due to active air circulation in karst hollowes the melting of snow cover begins from below even during minus air temperatures. A more intensive level rise begins during passing of air temperatures through zero. The time of the beginning of this rise of karst water levels ranges from the north to the south from July to April.

In the southern part of the Russian Platform (the Crimea, the Caucasus, the Dniester Area), in the zone with an unstable winter snow cover and sporadic freezing of the zone of aeration, karst water recharge, level rises and increase in spring yields begin with starting of autumn rains and in warm winters can proceed during the whole cold period, i.e., as long as spring. During colder winters, this recharge can be broken off because of formation of snow cover and continue again only in spring in February-March with the beginning of snow melting. In the first case, the continuous winter rise of levels and yields ends with a sprin g peak; in the second case, after the first, smaller by its size, autumn peak, the second spring peaks takes place that is higher, observed more often in March and February, more rarely in April. The rate of karst water recharge also depends on the climatic conditions, i.e., in some degree it is zonal, because the precipitation on the plain decreases from the north to the south, and evaporation increases. However, the rate of recharge depends considerably on hydrogeological conditions, primarily on the degree of permeability of the zone of aeration or the openness of the karst, and on the relief of an area. Izhorskoe plateau, where k arst is covered, and the relief is relatively slighty dissected, the modules of ground water flow change from 1-1.5 to 4-5, rarely 6 l/sec/km², averaging about 2 l/sec/km² /7/. At Ufimskoe Plateau with more opened karst and greater dissection of the relief (up to 0.2-0.7 km/km²) the modules of ground water flow change from 1-2 to 5-7, averaging about 4 l/sec/km². In the Mountaino us Crimea with open karst and intensively dissected relief the modules of ground water flow reach 8-60 l/sec/km², predominant values are 10-15 l/sec/km².

The portion of precipitation involved in ground water recharg e also depends on the degree of karst openness and on the correlation between precipitation and evaporation in the region. On Izhorskoe Plateau the coefficient of ground water flow, determining karst river discharges, especially in upper reach, changes from 4 to 27%, averages 10%. On Ufimskoe Plateau this coefficient reaches 20%, in the Crimea it averages about 40%, on some watersheds it is 80% and more. In the basin of the Biuk-Uzenbash River (village of Shchastlivoe), where the area of the watershed is 6.55 km², the surface runoff, formed by a group of springs, reaches 1250 mm per year, while the maximum long-term precipitation is 1400 mm per year. The module of annual runoff in the watershed is 39.7 l/sec/km², tha t of the dry season in 5-10% of annual average precipitation.

As known, the degree of regime fluctuation of the karst water dep ends on the degree of drainage of the territory (the rate of water exchange), the size of watershed areas, and the degree of moisture availability of a year. The zones of intensive water exchanges which are situated, as a rule, above the present basis of drainage, are the most variable (with a ratio of maximum to minimum y ields of more than 20). The karst spring yields of this zone respond to all more or less considerable falls of liquid precipitation in a watershed. The graphs of the regime of spring yields, constructed even from month average values, have a saw-like character (Fig.1a). The springs of the Crimea are the most variable among springs of comparable regions. The coefficient of spring fluctuation here in the zone of intensive water exchange reaches 20-600. Such great changeability of yields is determined, on the one hand, by a great amount of precipitation in the mountainous part of the Crimea, greater openness of the karst, that provides a high coefficient of ground water flow. On the other hand, such a dynamics is defined by the greater discharge of the karst massifs, and as a result the most of infiltrated moisture is quickly (during one season) discharged through flow of springs which reaches minimal values during dry seasons and often dries up at all.

The springs of the second zone are characterized by a smaller variation (5-20); this zone can be called active, slightly regulated. This zone is situated both above and slightly below the local basis of discharge. The extent of runoff regulation depends on the size of watershed areas, smaller seepage parameters of karstified deposits, and the presence of covering deposits. The springs of this zone do not deplete, the character of their intra-annual regime is smoother, with clearly expressed seasonal extremums (Fig.1b). The degree of moistening of not only the current but also of the previous year affects the character of this regime.

The springs of the third zone - the zone of the slow water exchange, with the greatest regulation both of recharge and discharge of ground water, are characterized by lesser variation(<5). Such a regulation occurs due to som e greater depths of karst water circulation, greater thickness of covering formations, remoteness of recharge areas from discharge areas. The springs of this zone, both gravity ones and ascending ones, have the smoother character of intra-annual changeability with extremums, shifted to 1-2 months in comparison with the springs of the first and the second types (Fig.1c). Besides the humidity of the current year, that of one or two and even more previous years affects the formation of their regime. The belonging of springs to this or that type can be determined not only according to the character of the graphs of regime and coefficients of variation of their yields, but to some other indice s - by peculiarities of changeability of coefficients of depletion and the degree (ratio) of their seasonal depletion, also by the degree of intra-series interrelation (autocorrelation) of annual average values of long-term series.

In the springs of the first type (the upper zone) a change in coefficients of depletion in time, according to seasonal decrease of spring yields, i s traced more clearly. This change- ability is well expressed on semilogarithmic graphs of the interrelation between spring yields and time (Fig.2), where at least three rectilinear segments are observed.

The first of them corresponds to the depletion of the largest channels and hollows of the karst massif, the second one is that of the large cracks, and the third one is that of the small cracks and pores. In years of high moisture availability the first rectilinear segment is longer and in years of low moisture availability it can, on the contrary, be invisible.

In the springs of the second type, more often only two rectilinear segments on such graphs are observed (see Fig.2). The intensity of yield, as it was marked, depends both on precipitation of the present year and on the character of moistening of the previous period. For example, for the Ai-Iori Spring, the coefficient of depletion in years of equal moisture availability and an identical value of recharge, i.e., with equal values of maximum yield, after a series of water-deficit years becomes 0.0025, and after a series of water-abundant years 0.0041, i.e., almost twice as greater.

In the springs of the third type (the third zone), the coefficients of depletion in years of different moisture availability are approximately equal (see Fig.2) and even in individual anomalously water-abundant years two rectilinear segments are observed on the graphs, similar to Fig.2. In some cases the character of the intra annual regime of spring yields is rather similar, even if the change in the intensity of precipitation is essential because the contribution of precipitation to karst water recharge of this zone is not great.

The different degree of the regulation of karst water discharge of individual hydrodynamic zones defined a different degree of intra-series relation between annual average values of ground water discharge. In springs of the first type, this interrelation (autocorrelation) is, as a rule, insignificant (Rt ₌₁ < 0.1). In springs of the second type it is also not great (Rt ₌₁ =0.1-0.2), and in springs of the third type it can reach 0.4-0.5. The long-term cyclicity or tendency to alternation of grouping of years of increased and decreased moisture availability manifest themselves most clearly in this regime of such springs. The most characteristic cycles for springs of the Russian Platform, including karst ones, are 2-3 years, 5-6 years and 10-15 years. The most reliable cycling in the Crimea according to spectrum analysis is 5-year (5.3 years) with splashes of spectrogrammes, essentially falling outside the limits of the confidence interval of 95%. The tendencies to 10 and 15-year cycling are defined obviously by their multiplicity with a 5-year one. On the Izhorskoe Plateau the most reliable cycling is 2-3 years, on Ufimskoe Plateau it is 6 and 12-years with tendencies to 2-4 years. The relative shortness of series of observation and character of the cycling do not permit us to speak about its reliability. As a rule, such cycles are not repeated systematically, this does not permit us to use such a phenomenon for forecasts. However, it is impossible not to take into consideration this tendency for practical solutions.

In years with high moisture availability annual average values of spring yields are 2-5 times greater than in years with low moisture availability; this is essential for solving questions of water supply, based (especially in the southern part of the Crimea) only on karst waters. For practical estimation of the degree of intra-annual changeability of karst springs discharges and rivers formed by springs, the notion about the ratio (norm) of spring seasonal depletion in a form of an inter-relation between minimal annual (month average) and annual average discharges should be introduced. For example, an average norm of depletion for two selected rivers of the Izhorskoe Plateau (rivers Yachera and Plussa) is 0 .2, i.e., during a dry season river discharges are only 20% of the annual flow. The average norm of depletion for the Ufimskoe Plateau (also on two characteristic rivers -Vogulka and Ufa) is 0.17, i.e., it is even smaller because the discharge of this territory is larger. For River Salgir in the Crimea, this norm becomes even smaller (0.13), i.e., here during dry season only 13% of the annual disc harge of the river remains because the drainage of the Crimea karst is the greatest among those of the comparable regions. The character of the intra-annual changeability karst water regime of all zones and regions essentially changes in years of different moisture availability. This manifests itself not only in changes of amplitudes of karst water level and discharge fluctuations, rates of their rises and falls but also in the time of the beginning of extremal positions of levels and discharges, their number in a year and also in the portion of precipitation, participating in ground water recharge, that is very important for predicting ground water regime in connection with human-induced transformations of the climate (Fig.3).

The character of the dependency of intra-annual karst water regime on the degree of moisture availability of a year can be estimated in two ways:

(a) having constructed a probability graph of annual average values of ground water yields or levels, years corresponding to average long term values (50% of probability) of discharges and water-short and water-abundant years of given probability can be estimated by this graph. The character of intra-annual ground water regime in selected years can be considered as a characteristic intra-annual regime for years of corresponding moisture availability (see Fig.1);

(b) according to tables of long-term observations, made, for example, from monthly average or ten-day data, the probability graphs for each month must be constructed; values of given probabilities (1, 5, 10, 20%, etc.) should be taken; calculation graphs of probable intra-annual distribution of ground water levels or yields for years of corresponding moisture availability can be made. An example of such graphs is given in Fig.4.

The comparison of these two ways of estimation shows that in the first way cases where extremal (maximal or minimal) values of ground water levels or discharges in years of different moisture availability can coincide and may appear irregular. Such a situation should be considered accidental, appeared due to the fact that the degree of moisture availability of some seasons of a year (precipitation) may be not coincide; therefore, the probability of annual average values cannot correspond to probabilities of extremal values of the same year. That is why we prefer the second way of estimation. Considering the results of this estimation in comparable regions of the Russian Platform, it must be emphasized that in some cases(see Fig.4) with the decrease in the degree of moisture availabil ity of a year amplitudes of levels also decrease, and in the others they, on the contrary, increase. This fact is connected with the character of the change in karstified deposit permeability in vertical direction. In cases where cracking of limestones essentially attenuates with depth, that is characteristic for the Izhorskoe Plateau and some areas of the Ufimskoe Plateau, ground water levels durin g water-short years lower and ground water circulates essentially in the zone with a water yield 2-3 times lesser on the average than in years of high moisture availability. Amplitudes of fluctuations of ground water levels, as it is known, are inversely proportional to the water yield of water-enclosing rocks. In conditions of relatively uniformity of fracture distribution in the vertical direction or even with some increase in deposit karstification near the base of drainage, that is characteristic for the Crimea and some areas of the Ufimskoe Plateau, amp litudes of fluctuations of spring yields are proportional to the degree of moisture availability of a year.

The mentioned high degree of interrelation between karst water regime and resources and precipitation allows us to use it as the basis for forecasting the probable changeability of karst water resources under the effect of human-induced transformations of the climate. The solution of this problem can be made with the help of the established variation of coefficients of ground or surface flow depending on the degree of moisture availability of a year. As it is known, the coefficient of ground water flow is the ratio of ground water flow to precipitation expressed in percentage, i.e. K=[(Q _mm/year) /(P _mm/year)]´EÀ 100%. The presence of direct and sufficiently high statistically significant correlations be tween precipitation and river discharge allows us to establish the dependence of values of ground water flow coefficients on the degree of moisture availability of a year, expressed in percentage of probability. An example of such dependencies is shown in Fig.5 for three rivers of the Mountainous Crimea-the Uchan-Su, situated on the southern slope of the mountains, and also for the Kokkozka and the Belbek, situated on the northern slope of the mountains. One can see in Fig.5 that with an increase in the degree of moisture availability of a year this coefficient increases, i.e., during years of high moisture availability part of precipitation, partcipating in recharge of karst waters, increases. The dependence of ground water flow coefficients on moisture availability of a year for water-shortage periods can be established in a similar way (Fig.5b). Thus, using predictive changes of precipitation, it is possible to establish the degree of moisture availability of a year from the probability plot of precipitation. Then from the graph of Fig.5 the value of ground water flow coefficient, corresponding to the given degree of moisture availability of a year for precipitation, can be obtained, and then using the formula, mentioned above, it is possible to calculate the predictive value of ground water flow, corresponding to obtained values of K and P. For example, in correspondence with the scenario of the predicted change of the climate of the State Hydrological Institute (GGI) /1/, in this region by the end of the century the decrease in the precipitation norm 10% is planned, i.e., the predictive average long-term norm of precipitation will reach 1090 mm/year, this will correspond to 60% probability of precipitation of the present period. The data of long-term observations at the meteorological station Ai-Petri, situated in the mountainous part of the massif, are used for calculations; here the main karst water recharge occurs. The coefficient of annual ground water flow (practically defining the whole surface flow in a basin) will reach 41% (see Fig.5), which for predicting the precipitation norm will define the flow equal to 446.9 l/sec or 14.2 l/sec.sq km. In comparison with the mean present flow module (16 l/sec.sq km) its decrease by 22% will occur. The minimum flow will also reduce to 63.22 l/sec or 2 l/sec.sq km, which for the mean present dry seasonal module 2.9 l/sec.sq km will make a decrease of up to 32%.

During the first decades of the next century (until 202 0), according to the scenario of climate change of GGI, some increase in precipitation to 1250 mm/year is expected that corresponds to 35% of precipitation probability. The coefficient of annual flow for River Uchan-Su for this precipitation probability will reach 49%, the coefficient of minimal flow will be 54.5%. The annual predictive flow will be 614 mm/year or 19.5 l/sec.sq km, the minimal flow will be 137 mm/year or 4.34 l/sec.sq km. In percentage proportion to the present long-term flow norm this change will make correspondingly +21% and +49%.

Probable predictive changes in karst water resources for two other c haracteristic drainage basins of the northern slope of the Mountainous Crimea have been calculated in a similar way. The results of these estimations can be illustrated by Table 1.

In a similar way the predictive estimations of changeability of karst wa ter resources of the Izhorskoe and Ufimskoe plateau were made. According to the sce nario of climatic change of GGI /1/ in the region of the Izhorskoe Plateau the de crease of precipitaion norm to 5% is expected till the end of the century, that corresponds to 508 mm/year or almost 60% of precipitation probability of the present period. The coefficient of annual flow for River Plussa will reach 37.9% that will define flow to 8900 l/sec or 6.14 l/sec.sq km for the predictive norm of precipitation. In comparison with the present module of the flow of 50%-probability, its decrease by 7% is expected. Dry season flow will also reduce to 2500 l/sec or 1.72 l/sec.sq km, i.e., by 25% in comparison with mean long-term present one.

                                                                                                                           Table 1

x) the value of module is in the numerator, its deviation from present one, expressed in percentage, is in the denominator.

For the River Yaschera basin for this period a decrease of annual flow of up to 3880 l/sec or 7.73 l/sec.sq km is expected, i.e., by 8% in comparison with the present module of 50%-probability. The dry season flow will reduce in this watershed to 750 l/sec or 1.49 l/sec.sq km, i.e., by 25%.

In the period till 2020 for this territory, according to the scenario of climatic change of GGI /1/, some increase in precipitation norm by 50 mm/year, i.e., to 585 mm/year is expected that corresponds to 30% of its probability.

For the River Plussa basin the coefficient of annual flow for this period will be 40.8%, that will define flow to 11100 l/sec or flow module to 7.65 l/s ec.sq km for the predictive norm of precipitation. Thus, in comparison with the present flow module of 50%-probability its increase by 15% will occur. A considerable (by 41%) increase of dry seasonal flow is expected, its module will be 2.83 l/sec.sq km. For the same period for the River Yaschera basin the value 52.5% of annual flow coefficient is predicted, that corresponds to the value 4940 l/sec of the flow or 9.84 l/sec.sq km of the flow module. Its comparison with the value of the present module of 50%-probability gives its increase by 17%. The dry season flow will also increase to 1600 l/sec or 3.19 l/sec. sq km that considerably (by 60%) exceeds the present module of 50%-probability.

For the territory of the Ufimskoe Plato, according to the scenario of climatic change of GGI /1/ by the end of the century the increase in the precipitation norm by 10% is predicted, it will make up 464 mm/year of 70% of precipitation probability of the present period. In correspondence with that, for the River Ufa basin the annual flow coefficient will be 39%, for the predictive norm of precipitation it will define the value of a flow equal to 82500 l/sec or 5.69 l/sec.sq km. In comparison with the present flow module of 50%-probability its decrease by 14% is expected. Also, the decrease of dry season flow to 17800 l/sec or 1.23 l/sec.sq km is predicted, that is by 19% less in comparison with the present dry season flow module of 50%-probability.

For the River Vogulka basin during this period the annual flow coefficient will reach 51.8%, that will define flow value equal to 7800 l/sec or module value equal to 7.57 l/sec.sq km, i.e., by 14% less than the present one. Dry season flow will also reduce to 1250 l/sec or 1.21 l/sec.sq km, by 24% less than the present one of 50%-probability.

For the period till 2020 for the territory of the Ufimskoe Plato, according to the scenario of climatic change of GGI, the decrease in the precipitation norm by 20 mm/year is expected, i.e., to 495 mm/year, which corresponds to its 60%-probability. For the River Ufa basin the annual flow coefficient will be 39.9%, that will define the value of the flow equal to 90000 l/sec or 6.21 l/sec.sq km. In comparison with the present flow module of 50%-probability its insignificant (by 6%) decrease will occur. Dry season flow will be 19800 l/sec or 1.36 l/sec.sq km, it is by 10% less than the present one.

The predictive annual flow coefficient for the River Vogulka will reach 53%. It will define annual flow equal to 8500 l/sec or 8.25 l/sec.sq km, i.e., by 7% less than the present module of 50%-probability. The dry season flow will also reduce to 1450 l/sec or 1.41l/sec.sq km, it is by 12% less than the present one.

The result of the calculations, presented above, are given in the Table 2.
                                                                                                                              Table 2

The analysis of obtained results shows that climatic changes, caused by the human impact, will lead in the near future to insignificant changes in precipitation (only ±E 10%). However, these changes in turn almost proportionally, but more considerably (to ±E 20-40%), will change annual yields of karst springs and total karst water resources. In different karst regions of the Russian Platform these changes will be opposite and at different scales. Moreover, it should be considered that minimal karst water discharge rates, which on the whole not rarely limit the development of water supply, can change more essentially to 20-50% of long-term norms; this obliges us to study this problem in more detail as applied to predicting the intra-annual distribution of karst water discharge in every region and drainage basin. Both extremal and average values of karst water resources and peculiarities of their intra-annual changeability, i.e., their seasonal regime, will be exposed to changes. The character of the intra-annual changeability of karst water regime and resources can be assessed in each concrete region by calculation graphs (the type of Fig.3) for each corresponding predictive level of probability. The transformations of intra-annual regime will be especially intensive for the springs of the first type and on watersheds with high modules of flow.

Considering the performed predictive estimations in the general dynamics of changeability of karst water resources in the Crimea, it should be mentioned that in most cases during the current century the common predominating tendency to the decrease of spring yields has been observed here. Among 58 observed springs, an obvious tendency to decrease of yields is observed in 32 springs, in 18 springs the regime was relatively stationary and only in 8 springs some yield rise in time was observed. The rates of such changeability are not great-from +0.01 to -0.01 -0.08 l/sec per sq km per year. The character of the most typical changeability of spring yields during long periods of time can be illustrated by the combinatory graph of the regime of two springs with the most prolonged periods of observation (Fig.6). Comparing the given graph with predictive values of karst river discharge, expressed in percentage of probability, it can be supposed that starting in 1985 the increase in spring yields will continue further but will not reach their long-term average values to the end of the century, however, it will correspond approximately to 60% of the probability level. However, in the beginning of the next century this increase of karst spring yields will continue and reach 30-40% of probability. Thus, predictive changes in karst water regime and resources will not go far outside the limits observed before. However, these changes, especially in minimal values of spring and small karst river discharge will be nevertheless considerable in comparison with present ones that must be taken into consideration for solving practical problems on regulation of water resources, planning of their use, etc.

For the territories of the Izhorsk oe and Ufimskoe plateau till the end of the current century a certain (to 15-20%) decrease in ground water resources is expected, which for the Ufimskoe Plato will last till 2020, but with a smaller rate (about 10%). In the region of the Izhorskoe Plato in the future (2020) a rather considerable increase in ground water resources is predicted. Dry season modules, which are used for estimation of ground water supplies, will increase by 40-60% that will allow us to improve the conditions of public water supply.

It can be foreseen that with the change in karst water recharge, some change in karstification processes will inevitably occur. Now, the removal of carbonates with ground water in the Crimea during dry seasons is effected at rate of 60-70 kg/day sq km and during the flood season, i.e., with recharge increase, it will reach 1900-2000 kg/day. The predictive increase both of maximal and minimal spring yields will lead in the future to a corresponding increase in the carbonate removal to 20-30% on the average that can cause definite changes in the environment and will require a separate discussion. In the region of the Izhorskoe Plato, at the present time, in the River Plussa basin the carbonate removal during the dry season is 56 kg/day.sq km, during the flood season it is 216 kg/day.sq km. Till the end of the current century some decrease of it can be expected, in the period to 2020 carbonate removal should be approximately 1.5 times greater that will lead to intensification of karstified processes, formation of new sinkholes, primarily in areas with absence or small thicknesses of overlapping covering glacial formations.

In the basin of the River Ufa (Ufimskoe Plato), ionic flow at the present time during the dry season is 62.5 kg/day.sq km (78.6 kg/day.sq km together with the sulphates),

during the flood period it is respectively 389 kg/day.sq km and 552 kg/day.sq km. The calculations show that during these periods (till 2000 and till 2020) an insignificant decrease in ionic flow is expected, therefore, for the territory of the Ufimskoe Plato activiztion of kartified processes is hardly probable. It is interesting to note that the rate of karstified processes in these rather different (by climatic and geological conditions) karst regions during the dry season is approximately equal and varies in the limits 50-70 kg/day.sq km of ionic flow. However, during the flood season in the semiarid zone (in the Crimea), ionic flow is 5-10 times greater than that in karst areas of the humid zone. Considering the fact that human-induced climatic changes will cause primarily changes in the precipitation of the winter period and will affect the determination of the flood volume, it can be supposed that it should affect karstified processes. In arid and semiarid zones, these processes will be especially active and that is why ecologically dangerous.

In conclusion, it must be once more mentioned that the investigations carried out permitted us to estimate the probable direction, scale and character of the karst water regime and resources changeability of three sufficiently large, di fferent by natural conditions, typical karst regions of the Russian Platform that, on the one hand, allows us to use the estimations for extrapolation over adjac

ent numerous karst regions, on the other hand, these estimations will promote the most rational planning of water resources use and management of these vast regions in the near future. And, finally, the analysis shows the importance and necessity of such estimates for all main karst regions of the world.

1. Budyko,M.I., 1988, The climate of the end of XX century. Me teorologia i Gidrologiya, No.10, P.5-25.

2. Gvozdeczky,N.A., 1954, Karst: Moscow, Geografgiz, P.352 (in Russian ).

3. Gorbunova,K.A., 1977, Karst of the gypsum of the USSR: Perm: Publ. House of Perm University, P.84 (in Russian).

4. Dublyanskii,K.N. and Kiknadze,T.Z., 1984, Hydrogeology of the karst of the Alpine folding area of the southern part of the USSR: Moscow, Nauka, P.128 (in Russian).

5. Kruber,A.A., 1915, The karst area of the Mountainous Crimea: Moscow , P.319 (in Russian).

6. Maksimovich,G.A., 1969, The basis of the karst science, Vols.I,II: Perm (in Russian).

7. Ground water flow of the area of the Central and Eastern Europe, 1982, Edited by A.A.Konoplyantsev, Moscow:VSEGINGEO, P.288 (in Russian).

8. Popov,V.G., 1976, The formation of ground water of the north-wester n Bashkiriya, Moscow: Nauka, P.160 (in Russian).

9. Sokolov,D.S., 1962, The main conditions of karst development, Mosco w: Gosgeoltechizdat, P.320 (in Russian).

 

Ezatolah Raeissi, Parsa Pezeshkpour and Farid Moore
Geology Department, College of Sciences, Shiraz University

Abstract: Gar and Barm Firooz mountains are located nor thwest of Shiraz in the Zagros. The two Mounts are mainly composed of calcareous Sarvak Formation, sandwiched between two impermeable shaly formations, namely Pabdeh-Gurpi at the top and Kazhdomi at the bottom. The main karst feature of the area is the presence of 259 sinkholes in the Sarvak Formation, which along with other superimposed secondary structures such as joints and fissures direct the rain and snow meltwater into the aquifer. The main discharge point is Sheshpeer spring. In order to study the characteristics of the aquifer, the major ions, electrical conductivity, temperature, and discharge were measured for a period of eighteen months. Moreover, carbon dioxide partial pressure, and saturation index of calcite and dolomite are calculated using a hydrochemical model.

The recession curve of the spring is indicative of two different flow regimes. In the first regime the flow is of conduit-diffused type, while in the second, the flow is mainly diffused and the larger channelways act as a drainage system.

The quality of karst water is essentially determined by the processes and reactions that it goes through from the time of precipitation until it is discharged from the aquifer. Rain water dissolves the atmospheric carbon dioxide during precipitation and while passing through the pore-spaces of the soil, the amount of the dissolved gas is increased due to biological activities. The dissolved carbon dioxide interact with limestones and dolomites and as result dissolution of latter occurs.

In the last three decades, numerous studies were carried out to determine the characteristics of karst aquifers using the physico-chemical properties of the discharging springs. Zolt^[1] , Smith and Mead^[2], Gams^[3], and Pitty ^[4,5] were the forerunners in this field of research. Garrels and Christ^[6] based on the amount of carbon dioxide of spring water classified the karst aquifers into two open systems namely diffused and conduit flow regimes, and concluded that total hardness variation is a suitable criteria in distinguishing between the two regimes. Their conclusion was reaffirmed by the results of Jacobson and Longmuir ^[7]. Atkinson ^[8] suggested that karst systems are networks of diffused and conduit flow regimes in which narrow fissures and joints play the main role in storing water. Scanlon and Thrailkill ^[9] using the suggested criteria by the previous workers have carried out a comprehensive study of conduit and diffuse flow regimes. Their results were not consistent with those of previous workers and they refuted the proposed criteria suggested for classification. Novak ^[10] , Ede ^[11] and Cowell and Ford ^[12] have suggested that diffused flow is characterised by small time temperature variations while big variations are indicative of conduit flow.

The study area which is a part of the Zagros Thrust Zone(Nabavi ^[13] ) is located 80 km west of Shiraz, Fars province Iran (51 50'-52 20'E and 30-30 30'N) (Fig.1). Gar and Barm-Firooz mountains make the heights of the study area with the maximum and minimum elevation of 3714 m and 2110 m respectively. The mean annual rainfall in Berghan station (Fig.1) with an elevation of 2110 m is 750 mm. The precipitation in winter is mainly in the form of snow, but most of the snow cover is melted by early April.

Gar and Barm-Firooz Mounts constitute the northern flanks of two big anticlines that extend in the general direction of Zagros Mountain Range. The exposed core of the anticline is dominantly made of calcareous Sarvak Formation (Albian-Turonian) which is underlaid and overlaid by impermeable shales of kazhdomi (Aptian-Cenemonian) and Pabdeh-Gurpi (Santonian-Oligocene) Formations respectively. The main tectonic feature is the presence of a major thrust fault (Fig.1). The northern flank of the anticline has been brought up by the tectonic forces and southern flank is so shattered that it is either completely removed or can be seen as large slide blocks. Several normal and strike slip faults also occur and the overall tectonic setting of the area has produced suitable conditions for extensive karstification. The most important karst feature is the presence of 160 sinkholes in Gar, and 99 sinkholes in Barm-Firooz Mounts, (Fig.1). As can be seen the sinkholes follow the same trend, which evidently coincides with the direction of longitudinal faults.

The physico-chemical parameters of Sheshpeer spring as the main discharge point of Gar and Barm-Firooz Mounts were measured every three weeks between April 1990 and July 1991. The temperature, electrical conductivity, carbon dioxide and dissolved oxygen were measured at the site. Magnesium was measured by atomic absorption, calcium, sodium and potassium were measured by flame photometric methods. The carbonate and bicarbonate anions were measured using standard titration methods. Chlorine and sulfate were determined using Mohr and turbidimetry methods respectively. Carbon dioxide partial pressure (P_CO2), calcium saturation index (SIC) and dolomite saturation index (SID) is calculated using WATEQF model (plummer et al.^[14] ). The discharge was measured by current meter and the stage-discharge curved is prepared.

The catchment area of Sheshpeer spring is 81 km². According to Raeissi et al.[^15] the sinkholes seem to be connected by rather large channelways at depth.

The hydrograph of Sheshpeer spring in the period 1990-1991 is presented is Fig.2(a). Using this hydrograph, the recession curves of the spring is presented in Fig.2(b). The recession curves indicate two different discharge coefficients and thus two different a ₁ and a ₂ discharge regimes(Table 1).

The base flow and quick flow of both regimes were determined from th e hydrograph and are presented in Table 1. As it can be seen almost 40 percent of a ₁ regime is produced by the quick flow and the remaining is contributed by the base flow, whereas in the a ₂, the base flow constitutes the whole flow. The coincid ence of the a ₁ regime with snow melting period suggests that the meltwater enter s the conduits througth sinkholes, joints and fissures and quickly discharges from Sheshpeer spring. In a ₂ regime which coincides with the dry season, and no re charge from the rain or snow melting occurs, the stored water in the pore spaces, small joints and fissures gradually discharges into the large conduits and makes up the base flow. The large conduit in the second regime does not act as a reservoir for the stored water, and merely provides a water transportation medium.

The minimum and maximum electrical conductivity is 243 and 295 m/cm respectively. The type of water is Ca carbonatic. The relation between time and various physical and chemical parameter are depicted in Fig.3. Time can be divided into three distinct periods, namely a ₁, a ₂ and the wet season period. The elec trical conductivity, total hardness, calcium and bicarbonate ions in the a ₁ period ar e lower compared with those of a ₂ period. The reason for this observation is that in the a ₁ regime as the water enters the conduits through sinkholes and quic kly discharges from Sheshpeer spring the contact surface and the residence time of water is appreciably lower than that of a ₂ regime in which slow passage of wa ter increases the surface contact and residence time. The rather quick discharge of water in a ₁ does not allow it to become saturated in calcium; while in a ₂, the calculated SIc indicates the water is saturated in this ion. At the beginning of wet season with increasing discharge, electrical conductivity, total hardmess and the amount of calcium and magnesium increase, but towards the end of this period these parameters begin to decline again. The initial increase is probably caused by the accumulation of evaporitic salts at the surface in dry season and then quick dissolution and infiltration of these salts into the aquifer at the beginning of the wet season. As the wet season proceeds, the amount of surfacial salts and hence the amount of dissolved ions decrease.

The maximum and minimum temperatures of the spring during the study, was 9.2 and 8.1°E respectively with an average of 8.4°E . The comparison of the spring and the atmospheric temperature suggest that no correlation exist between the two. It seems that the temperature of the aquifer has equilibrated with the temperature of the calcarious rock masses. Moreover, the water flows at the depth of more than 100 meters (Raeissi et al ^[15] ) and at this depth where an appreciable part of the flow is supplied by the base flow, the temperature can not be affected by surfacial temperature fluctuations and remains virtually constant throughout the year. The minor changes of temperature which well correlate with discharge are presented in Fig.3. As mentioned earlier, the increasing discharge is directly related to the infiltration of snow meltwater through the sinkholes, the temperature of the meltwater is more than that of the aquifer and thus the observed slight temperature increase is probably caused by the mixing of quick flow.

The mean, standard deviation and coefficient of variation of discharge, temperature, total hardness, electrical conductivity, total dissolved salts and dissolved ions of Sheshpeer spring are presented in Table 2. Attempts to determine Sheshpeer spring flow system using the criteria proposed by various authors has produced contradictory results. For instance, using Shuster and White ^[16] criteria, Sheshpeer flow system must be classified as conduit, while according to the criteria of Novak ^[10] , Ede ^[11] , Cowell & Ford ^[12] it is diffused flow. Jacobson and Longmuir ^[7] scheme can not be used at all since some parameters are indicative of diffused and others of conduit flow. There is no doubt that none of the available classifications gives the full answer to the problem of classification of the flow systems, as they seem to be based on insignificant or nonuseful variants. Probably many other variables must be taken into account if a comprehensive and useful classification is to be presented. Some of the parameters to be considered include the percentage of quick and base flows, presence or absence of sinkholes and large fissures, shape and surface area of drainage , lag time, standard deviation of temperature etc.. Disregarding the available classifications, an attempt is made here to propose a likely model for Sheshpeer spring flow regime using the determined physical and chemical characteristics.

As mentioned Sheshpeer hydrograph is made of two distinct flow regimes. The hydrograph indicates that 40 percent of the flow is contributed by quick flow through sinkholes and large fissures. The infiltrated water in small joints and fissures produces 60 percent of the flow. Hence in the first regime, the conduit to diffused flow ratio is 40:60. The quick passage of water has resulted in the total hardness, electrical conductivity, total dissolved solids and calcium and bicarbonate ions to be less than that of the second regime. In addition to transporting water, the large channelways also play a storing role in this regime. In the second regime where there is no snow meltwater and rain during the dry season, the sinkholes do not have a significant role in contributing water to the system. In these circumstances, the stored water in small fissures in winter and spring gradually enters the large conduits and keeps the spring running, though with a lower discharge rate. Hence, the storing role of large conduits in this regime is totally eliminated. The flow regime is diffused and the base flow is the only contributing agent. Electrical conductivity, total hardness, total dissolved solids and the amount of calcium and bicarbonate ions are higher due to diffused flow.

The autors would like to thank the research council of Shiraz University for their finnancial support.

REFERENCES

1. Zolt J., Die hydrographic des nordost alpinem karsts, Steirische Beitrage Hydrogeologie (1960/1961) 2, 183 (1960).

2. Smith D.I. and Mead D.G., The solution of limestone, Proc. Univ. Br istol Seleo. Soc. 9(3), 188-211 (1962).

3. Gams J., Factors and dynamics of corrosion of the carbonate rocks i n the Dinaric and Alpian karst of Slovenia (Yugoslavia), Geografski Vestink 38, 11-68 (1960).

4. Pitty A.F., An approach of discharge from a karst rising by natural salt dilution, J.Hydrol. 4, 63-69(1966).

5. Pitty A.F., Some features of calcium hardness fluctuations in two karst streams and their possible value in geohydrological studies, J.Hydrol. 5, 202-208 (1968).

6. Garrels R.M. and Christ C.L. Solutions, minerals and Equilibria, Ha rper and Row, New York, N.Y., 2nd ed., 450(1965).

7. Jacobson R.L. and Longmuir D., Controls on the quality variations o f some carbonate spring waters, J.Hydrol. 23, 247-265(1974).

8. Atkinson T.C., Diffuse flow in limestone terrain in the Mendlip hil ls, Somerset (G.B.), J.Hydrol.35,93-110(1977).

9. Scanlon B.R. and Thrailkill J., Chemical similarities among physica lly distinct spring types in a karst terrain, J.Hydrol. 89, 259-279(1978).

10. Novak D., A contribution to the knowledge of physical and chemical properties of the ground water in the Slovenian karst, Krs Jugoslavije (Cars us Jugoslavie) 715, 171-188(1971).

11. Ede D.P., Comment on "Seasonal fluctuations in the chemistry of limestone springs "By: Evan T. Shuster and William B.White,J.Hydrol.16, 53-55(1972).

12. Cowell D.W. and Ford D.C., Karst hydrology of the Bruce Peninsula, Ontario, Canada, In:Back W., La Moreax P.E. (Guest-Eds) V.T. Stringfield Symposium processes in karst hydrology, J.Hydrol. 61, 163-168(1983).

13. Nabavi H., Brief description of geology of Iran, Geological Societ y of Iran, Tehran(1975).

14. Plummer L.N. et al, WATEQF, A FORTRAN IV version of WATEQ, A compu ter program for calculating chemical equilibrium of natural waters, International Groundwater Modeling Centre, US. Geol. Sur., Reston(1984).

15. Raeissi E., Samani n. and Moore F., Karst hydrogeology of the Sepi dan Region, Fars Province of Iran, International Symposium and field seminar on hydrogeological processes in karst terranes, Antalya, Turkey, 7-17 Oct. (1990).

16. Shuster E.T. and White W.B., Seasonal fluctuations in the chemistr y of limestone springs: A possible means for characterizing carbonate aquifers, J. Hydrol. 14, 93-128)(1971).

 

Petar Milanovic, Energoprojekt, Beograd, Yugoslavia
Veljko Jokanovic, Karst Institute, Trebinje, Yugoslavia

The question concerning the hydrogeological characteristics of conglomerates has been recently raised several times. It relates, first of all, to the karstification of these rock masses, i.e. whether they are liable to karstification and which karst shapes can be formed in them. The problem of watertightmess of conglomerates has been studied from the point of view of surface storages construction, as well as types of aquifers formed in these rocks and possibilities of intake of this water.

large scale investigation works, which have been carried out during about twenty past years in the Nevesinje field for the requirements of the Trebisnjica Hydrosystem Project, made it possible to define rather exactly the hydrogeological characteristics of, so-called, Promina series conglomerates. Beside the investigations for the purpose of defining the future storages watertightness, some aquifer zones have also been investigated with aim to determine their yield and find out a possibility of an artificial discharge regulation.

Thick Promia series sediments have been deposited at several locations in the dinarides karst zone. Beside their classical locality - Promina mountain near Drnis Town, large masses of these sediments have been deposited in the zones near Posusje, in the Nevesinje field, and the north-western rims of Dabar field are built-up of these sediments as well. Such isolated phenomena are not particularly important or characteristic from the hydrogeological point of view.

The Promina series constitute the Paleogene molasse type sediments. In the Nevesinje field these sediments thickness exceeds 700 m. Conglomerates represent a predominant lithological member, and therefore the term Promina series often means exclusively this kind of sediments. The lithologic column indicates a non-uniformity of sedimented material. In deeper zones, pebbles and boulders prevail as well as slightly rounded cretaceous particles ranging from some milimetres to more than one meter in size, which are cemented together by means of carbonate matrix. Alveoline-nummulite limestones are, also present but to a less significant extent. Pebbles, boulders and cretaceous particles are cemented together by carbonate and sandy substances. These sediments are overlain by thick conglomerate masses whose pebbles and boulders originate from sediments of different age varying from Werfenian to Eocene. Volcanic rocks' boulders and pebbles (gabro and diabase) are often encountered in this zone. The final sequence consists of conglomerates with carbonate pebbles and bouldes of uniform composition. Both in the middle and in the upper sequences these sediments are cemented by carbonate and sandy matrix.

In the few localities the Promina series include, beside conglomerate, the marlstone zone as well. As a result of exploratory boring in this localites, in the geological column of Promina four separate marly zones of the total thickness of 44 m have been encountered down to the depth of 100 m. Along other locality reach, the existance of six marly zones of total thickness amounting to 75 m, wa s established to the depth of 162 m.

The geophysical investigation works confirmed that the carbonate paleorelief of the depression, in which a rapid sedimentation of these molasses has happened, has an expressly hilly topography.

Some parts of this relief represent the depressions which are deep to the elevation +50m, according to the geoelectrical soundings, while in the other area the limestone reefs are outcropping on the terrain surface. The surface altitude is about 850 m.

These layers, in majority of cases, are concordant over Eocene flysch sediments and discordant over the older deposits, although their lateral boundaries are undoubtedly of tectonic origin. Subvertical to vertical tectonic boundary separates the Promina conglomerate mass from the Velez carbonate massif. The location of this contact has been confirmed by boring in the immediate vicinity of the fault zone, at the foothill of Velez, mountain.

The hydrogeological characteristics of the Promina series and its hydro