RECENT RESEARCH BY IGCP 299 PARTICIPANTS
The problem of space and solar influences on the environment has been dis-cussed in the past in the framework of several ICSU bodies like SCOSTEP and COSPAR and in international institution as the International Center for Theoretical Physics and the International Center for Earth and Environment Sciences. A meeting was held in Rozhen , Bulgaria to discuss this problem , September , 1990.
The relevant value of the international efforts represented by the International Geosphere- Biosphere Program (IGBP) and the Solar-Terrestrial Energy Program (STEP) was recognized and their scopes were reviewed. The lack of sufficient atten-tion to the problem of solar variability and space effects on the earth environment in these programs was pointed out. This particular problem was analyzed.
The evidences of statistical correlation between solar variability and lower atmosphere parameters were discussed recognizing the need for a careful scientific search for confirmation of these types of statistical results and an understanding of the possible physical mechanism involved.
Other aspects discussed were those related to the possible solar variability and space influences on the solid earth , oceans and the biosphere. The need for serious scientific efforts in exploring all routes to prove or disprove the existence of such influences was stressed.
In summary , the importance of the definition and understanding of the possible mechanisms by which solar energy variations and space conditions can influence the earth environment was stressed.
The scientists attending the meeting decided to make the following reco-mmendations:
1. The relationship between the international programs IGBP and STEP should be increased making use of all possible means to establish the necessary interface between them , including the possibility to set up an adhoc working group on the subject with clear term of reference.
2. This interface should consider in particular the problem of the solar variability and space influence on the earth environment : the atmosphere , the solid earth , the oceans and biosphere.
3. The study of these influences should include the analysis of possible earth paleoeffects of those external factors by means of dendrochronological , cosmogenic radio-nuclides variations , luminescence of speleothems and fossil records in sedi-ments and other similar studies.
4. Solar-terrestrial relationships should include new methodological approaches for the study of the environment in a systematic way. These new studies should start from the investigation of the atmospheric system interactions.
5. The recommended actions should be carried out in a truly international context including the active participation of developing countries.
6. This participants should take into account the existence of projects like the International Center for Earth and Environmental Sciences , being established in Trieste , Italy , by UNIDO , that could promote , coordinate and integrate the parti-cipation of scientists from developing countries in international programs.
Y.Y.Shopov , V.Dermendjiev , G.Buyukliev(Bulgaria)
A new method for perfect dating of natural materials with periodical macro-structure and with annual or daily cyclicity in their formation (like Trees , bottom sediments , fossils , corals , speleothems and others) by autocalibration is proposed. The base of this " Autocalibration dating " is the determination of the growth rate of the sample by power spectral analysis of time serial of given property of the sample having periodical cyclic recurrence. This time serial are obtained by scanning of a cross section of the investigated material. Advantages of the proposed method are its high precision independent of the age of the sample and its applicability for dating of all natural materials with periodical macrostructure having characterizing values , displaying annual or daily cyclic recurrence. Some typical properties of the solar cycle are determined in the luminescent time serial of cave flowstones from Bulgaria.
To clarify the cyclic recurrence of the short-time variations of the climate and solar activity (SA) the method Laser Luminescent Micro Zonal Analysis(LLMZA) was proposed.
Preparation of time serial with very different resolution (which can vary more than 1000 times) and different periods become available with the elaboration of this method , which allows research of either long or short-time minima and maxima of the SA and general statistical comformities of the cyclic recurrence of the SA.
Up to now exists information for cycles of solar activity from direct measure-ments for 240 years , data from dendrochronology of tree rings for 7400 years ago with resolution 1 yr , and 14C data for the last 10000 yrs. After calibration with these data , the LLMZA method can be used for obtaining such information with higher resolution (up to 3 days) from up to several millions years ago (the age of the oldest flowstones).
The aim of this work is to develop an useful method for calibration of high resolution time seria by ages on the example of the time seria of a new indirect solar activity index: "Intensity of Luminescence of the Microzones of Cave Flowstones".
The main cycle of the SA , is 11 annual cycle. It is named solar cycle , because it is habitual for all phenomena and indexes of the solar activity (SA). We study the properties of the SA by the Intensity of Luminescence of the Cave Flowstone Micro-zones. This index is in anticorrelation with the index "deposition rate" of 14C (Fig.1) and in direct correlation with the solar activity as the thermoluminescent time series of sediment cores. The luminescence of the calcite cave flowstones at Laser irradiation is activated usually by organic admixtures.The luminescent centres in cave flowstones are organic molecules which pene-trated into cave from products of life processes of plants , growing over caves. The quantity of this products coming from photosynthesis strongly depends on the solar irradiation. Therefore intensity of luminescence of cave flowstones have revealed a strong annual cyclicrecourrence (independently of that cave flowstones usually have no visible annual rings). Its allows to calculate the mean annual growth rate of the flowstone , by determination of the linear length of the mean annual period in the cross section by power spectral analysis.
Fig.1 Comparison of LLMZA with 14C data:
a)luminescence time serial of cave flowstone with resolution 5 yrs/px. obtained by SHOPOVS method(1988); b)inverse curve of 14C data and its interpolation c)as a long-term solar activity envelope (of possible sunspot cycles) by EDDY(1978).
The intensity of luminescence of the microzones in cave flowstones is deter-mined mainly by the SA during the formation of corresponding zone. This way the curve of intensity of its luminescence in dependence of the distance from the spe-leothem surface will present a time series of the changes of the past SA versus the age of rings in the flowstone. The paleoclimate can have only a feeble influence over the width of the zones. After formation of the corresponding zone it is safe from further actions and saves information for the SA during its formation. It is conformed by the series which show well pronounced 11-yrs cycles by which form of general properties of the Solar Activity can be obtained.
Luminescent time serial was obtained by irradiation of a polished cross section of cave flowstone with N2-Laser and photography of its luminescence through a microscope. The obtained negative was developed with a scanning microdesito-meter with automatical transformation of the density of blacking of the emulsion in digital form with recording on magnetic type and drawing on plotter.
An example of a luminescent time seria with resolution of 125 px/yr is shown in Fig.2. Density of blacking of the emulsion of the negative, which is proportional to the concentration of luminescent organic molecules is placed on the axis of ordinates , and the number of the measurements(pixels, which number is proportional to the age of the flowstones and 1 pixel is a time step of the series) is placed on the abscissa axis. The annual cycle is good visible in this 33 years long time series. All shown time seria are obtained from a cave flowstone from Bulgaria.
Fig.2 LLMZA curve of the season climatic variations with , resolution 3 days(125 px/yr)
To study the periods of the periodical macrostructures of the sample with a proper statistical accuracy, we regard this data as a time series(time dependent process) and use the method of mathematical power spectral analysis.
Fig.3 LLMZA curve with resolution 2.4 months , (4.74px/yr).
The obtained ( from the luminescent time series shown in Fig.3 ) power spectrum after using of high frequency filter is shown in Fig.4. It shows that by this way we can reliably determine the annual growth rate of the sample. This spectrum shows that during 750 yrs(length of developed time series) the annual growth rate of the speleothem were constant, because the annual peak in the power spectrum of this time seria is single and very narrow. Therefore power analysis of the luminescent time series can be used for prefect dating of the sample. If we know approximately the average annual growth rate of the speleothem (obtained from its absolute dating) we can indentified the annual pl44 peak in the power spectra of its luminescent time seria and we can determine the perfect annual growth rate of the sample from the position of this peak. If we know the linear dimensions of the developed time seria we can determine the perfect relative age of each part of this piece of the sample. If the speleothem grew without interruptions up to the time of getting the sample we can determine absolute age of the sample.
Fig.4 A)High frequency filtered spectra of LLMZA time series for 720 yrs from Fig.3; B)power spectrum of the Wolf numbers time seria obtained from direct measurements of the Sun spots. (RIVIN, 1989).
In our case we know from previous ESR dating that the average growth rate of investigated flowstone is about 1.70±0.2 micrometers/yr but from the position of the annual peak we determine the perfect annual growth rate of 1.58 micrometers/year.
The splittings of the 11-annual SA peak, observed in Fig.4.A, are due to the availability of binary, singular, three-and four-cyclic 11 years cycles with different lengths. The intensity and position of this peaks are indentical to that obtained from RIVIN from the power spectrum(Fig.4.B) of the Wolf numbers time seria (obtained from direct measurements of the Sun spots).
Periods of 11(13.3; 10.4 and 8.8), 1 and 2 yrs were determined by power spectra (Fig.4.A) of time seria with resolution 4,743 px/yr.
We named this dating approach as "Autocalibration Dating". The advantage of the proposed method is its high precision independent of the age of the sample. Our opinion is that it is applicable for relative dating of all natural materials with periodical macro-structure having characterizing values (like extinction, intensity of luminescence or thermoluminescence, concentration of given ion or others), displaying annual or daily cyclic recourrence (including samples without visible annual rings) like rhytmites, sea and lake cores, plant fossiles, cave flowstones, trees and others, and for absolute dating if it grew till now.
HYDROGEOCHEMICAL PATTERNS AND MATHEMATICAL CORRELATIONS IN KARST AT THE EXAMPLES OF CUBA
J.R.Fagundo Castillo and J.E.Rodriguez Rubio (Cuba)
In this paper, the hydrogeochemical patterns of some karst and non karstic waters from Cuba , as well as the mathematical correlations between ionic contents and electric conductivity of the waters, are presented. Anthropogenic on karst are also discussed in terms of variations in mineralization , hydrogeochemical patterns and mathematical relationship in the long run.
Materials and Methods
As criterion of good mathematical agreement we use in this paper the similarity index SI defined by:
R1: relation between the ionic concentration obtained by chemical analysis and modeling;
R2: relation between each ion and the total sum of ions.
Further control of chemical composition of waters can be made by means of the corresponding mathematical equations and the measurement "in situ" of electric conductivity. The theory which support the use of referred computer programs has been recently reported ( Fagundo , 1990).
The hydrogeochemical patterns are represented in this paper by means of the diagrams proposed by Stiff(1951) and the stecheometric relations Na++K+:Ca2+: Mg2+:Cl-:HCO3-:SO42- , where the sum of anions and cations are both equal to 10 meq/1.
Results and Discussion
In order to study the physical chemical behaviour of the karst waters , its hydro-geochemical patterns and changes developed by the effect of natural and anthro-pogenic factors , two typical Cuban karst areas were chosen : San Marcos river basin in Sierra del Rosario and the developed karst in southern plain , both in Pinar del Rio province , representatives of mountain and coastal plain tropical karst , respectively.
San Marcos River Basin
The lithology and the water flow conditions are the major factors that determine the chemical composition of the waters and the hydrogeochemical patterns. We can distinguish the following water types: sodium calcium hydrocarbonate for waters from the sedimentary-effusive rocks , magnesium hydrocarbonate for the waters which originate in the ultrabasic massif , and calcium hydrocarbonate for that waters which flow in the karst areas (at the source , caves , exsurgences and springs from the saturation zone ). Finally , there are waters of calcium sulphate type from the karst deep drainage (deep phreatic zone).
These waters change the absolute chemical composition as a consequence of the rain regime , but practically do not undergo changes in its relative chemical composition. The ion stecheometric relations are the same for each sample. Similar bahaviour in other systematic sampling points in other regions was observed.
The hydrogeochemical patterns of the waters from San Marcos basin in terms of the corresponding stecheometric relations, appear in Tab.1.
Linear equations were obtained when concentration in each ion and electric conductivity data were fitted. The slopes of the corresponding regression equations are also listed in Tab.1. The magnitude of the slopes are functions of the ionic concentrations of the waters and the local lithology.Three hydrogeochemical patterns characterize all karst waters of the basin and there are other two for the non karstic waters.
The mean similarity index between real and theoretical values of the chemical composition is also expressed for each type of water in Tab.1.
Pinar del Rio Southern Coastal Karstic Plains
In the southern part of Pinar del Rio province , there are a great karst massif constituted by Miocene limestones , partially dolomitized and occasionally covered by Quaternary sediments. In this area , a rich aquifer occurs whose recharge zone is in the premountains region at the North , and it is freely discharged to the sea at the South. The waters in the aquifers are of calcium hydrocarbonate type in the zone non affected by the seawater mixing. Toward the coast , some hydrochemical facies occur as the result of the mixing between fresh and marine waters. They are stratified along the vertical profile of each well and a horizontal profile across the aquifers (Arellano and Fagundo , 1985).
There are also different modes of water chemical evolution in this region , which depend on the dolomitization degree of the sampling site inside the aquifer. In such conditions different contents of magnesium for the same seawater mixing level exist. We have observed at least , four chemical evolution paths for the waters of these regions as well as for other coastal karst aquifers in Cuba.
We have occasionally observed changes in the original hydrogeochemical patterns in some sampling points (well) in the long run. Generally , it is due to a decrease in the rain regime and/or an increase in the aquifer overexploitation. In this case , the mineralization and NaCl salinity showed a progressive increase during the observational period. The additional quantity of foreign ions as Na+ , K+ and Cl- in hydrocarbonate water increase calcite and dolomite solubility and considerable quantity of carbonate rock can be dissolved from the aquifer.
In this type of water the corresponding fitting of the ion contents and electric conductivity data is more significant for the second degree than linear equations if all the data are processed. Better results can be obtained processing the data corresponding to each hydrogeochemical pattern(see table 2).
In this case , mathematical equations are of linear type. Using these expresions and the electric conductivity measurement in field by means of a conductometer connected to a 100m probe it is possible to control the chemical composition and salinity of the waters , but we need to take into account the range in which each sampling point reflects the different hydrogeochemical pattern(see table 3).
The lithology and the water flow conditions determine the hydrogeochemical patterns , characterized by a given stecheometric relation. In the case of tropical karst and non karstic waters there is , generally , one hydrogeochemical pattern in the same sampling point , where many of the factors remain constants. In case of underground waters there are less changes of the relative chemical composition than in the first surface waters. A discret number of hydrogeochemical patterns can characterize all the waters running through the limestones.
More variability can be distinguish in coastal karst aquifers encroached by seawaters , where waters in the aquifer are stratified along vertical and horizontal profiles. In such cases, different chemical facies in the same well occur.
The human activity can change the natural hydrogeochemical patterns in the karst as a consequence of the waste water input , the chemical treatment in the agriculture and the aquifer overexploitation. In coastal karst areas , the latter increases signifi-cantly the water salinity and the karstic processes.
In all the cases , empirical mathematical relationships were found between ionic chemical composition and the electric conductivity of the waters. In one of the controlling factors of the chemical composition acquisition is dominant , as for instance , the lithology , the most accurate equations are of the linear Type , but if more than one of these factors play the major role in the mode of chemical compo-sition acquisition we can found that non linear equation are the better when all the data are processed, and linear equation are the best when the corresponding data of each hydrogeochemical pattern are separately processed. By means of these equations and field measurements of electric conductivity it is possible to control the water quality in terms of chemical composition, mineralization and salinity.
Tab.1 Hydrogeochemical patterns (as a function of the stecheometric relations); slopes of the linear relationship between ionic concentration and electric conductivity of the water from the San Marccs river basin, and the similarity index (SI) between real and modelling values of the chemical composition
Geological environment N stecheometric relation slope of the regression equation SI
Na+K Ca Mg Cl HCO3 SO4 HCO3 Cl SO4 Ca Mg Na+K _________________________________________________________________________________________
Sedimentary-effusive 34 3 5 2 1 9 0 10.013 1.276 0.393 5.947 1.933 3.802 0.894
Ultrabasic 13 1 0 9 0 9 1 10.537 1.253 0.332 0.338 10.296 1.478 0.898
Limestones from Guajaibon
and Chiquita formations 140 2 7 1 1 8 1 8.994 1.003 1.148 7.148 7.832 1.242 0.883
Limestones from Mil
Cumbres region 27 2 7 1 1 8 1 9.57 0.912 1.405 8.751 1.005 2.131 0.893
Water from karst deep
drainage 12 2 7 1 0 1 9 0.781 0.276 7.866 6.256 1.157 1.510 0.978
Tab.2 Hydrogeochemical patterns (as a function of the stecheometric relations) slopes of the linear relationship between ionic concentration and electric conductivity of the water from some wells of Pinar del Rio s outhern coastal karst aquifer and similarity index (SI) between real and modelling value of the chemical composition
Hydrogeochemical N Stecheometric relation slope of the regression equation SI
pattern Na+K Ca Mg Cl HCO3 SO4 HCO3 Cl SO4 Ca Mg Na+K _________________________________________________________________________________________
HP1 4 2 8 0 2 8 0 6.558 1.923 0.251 6.890 0.438 1.404 0.932
HP2 5 2 7 1 4 6 0 5.609 3.541 0.227 5.884 1.000 2.493 0.923
HP3 3 4 5 1 5 5 0 4.583 4.570 0.449 4.924 1.149 3.529 0.958
HP4 4 5 4 1 6 4 0 3.685 5.421 0.419 4.008 1.229 4.218 0.945
HP5 10 5 3 2 6 4 0 3.134 6.019 0.367 3.340 1.311 4.869 0.898
HP6 4 6 3 1 7 3 0 2.436 7.487 0.406 3.121 1.618 5.590 0.936
HP7 11 6 3 1 8 2 0 1.710 7.778 0.633 2.510 1.492 6.119 0.919
HP8 21 7 2 1 8 1 1 0.986 8.055 0.574 1.604 1.400 6.611 0.931
HP9 6 7 1 2 9 1 0 0.628 8.477 0.558 1.265 1.700 6.698 0.941
HP10 7 8 1 1 9 1 0.282 8.913 0.665 0.844 1.419 7.567 0.944 __________________________________________________________________________________________
Tab.3 Electric conductivity ranges in which each well from part of the Pinar del
Rio coastal karst aquifer reflects the different hydrogeochemical patterns ___________________________________________________________________________________
Well Deep HP1 HP2 HP3 HP4 HP5 HP6 HP7 HP8 HP9 HP10 __________________________________________________________________________________
P2 60-100 300-399 400-585 590-689 690-969 970-1219 1200-1879 1820-3779 3780-4691 4700-6000 >6000
P4 60-90 600-794 800-1279 1200-1799 1800-2449 2450-5159 5160-7000 >7000
P5 20-50 500-999 1000-1699 1700-1839 1840-4249 4250-7709 >7710
P1 70-100 400-529 530-649 650-779 780-950
P6 60-90 200-359 360-449 450-1699 1700-4000
P3 30-40 600-999 1000-1699 1700-2288 2300-2899 2900-4399 4400-8299 >8300
P7 40-70 500-849 950-4129 4130-7399 >7400 ________________________________________________________________________________
J.E.Redriguez and J.R.Fagundo (Cuba)
Since 1975 , Cuban karst hydrological and hydrochemical characteristics and the dynamics and intensity of the karstic processes,have being investigated by a group of Cuban specialists.
A research program in order to asses intensity of the contemporary karstic processes in some karstic regions of the world started in 1984. This research program is a part of the Cuban- Polish collaboration on the International Commi-ssion for Physico-Chemical and Hydrological Karst Research of International Union of Speleology.
The Pan de Guajaibon massif in western Cuba was chosen for this research as an experimental representative area of the tropical lower mountain karst. Other karstic localities in plains , hills and lower mountains were also chosen for developing similar investigations , as validaion areas.
Some results of the hydrodynamic and hydrogeochemical characteristics of the karstic massifs were obtained and different karst circulation regimes were found , as well as the quantitative determination of these massifs response for rainfalls by using a typical water debit response curves and hydrochemical composition. Moreover , the influence of intensive tropical rains action and their spetial and temporary distribution on the karst denudation process were studied.
The karst denudation was calculated by a hydrochemical method. Values of 40-50 and 115-130 m3/km2 year respectively were reported in Pan de Guajaibon massif. Same values in another validation karstic areas of the country have been determined.
About the 65% of Cuban territory (71,500km2) is covered by limestones from Jurassic to Quaternary age , in greater or lesser degree affected by the karstic processes , where 85% of the underground water reserves in the country are concentrated and the large number of rivers are circulating in direct interaction with this geological environment.
The rainfall amount and its spatial and temporary distribution together with other non-climatic factors , e.g. , lithology , relief , geological structure , hydrology and vegetation , have greatly influenced the karst development intensity and its typology as well.
Thus , the joined occurrence and development of many karst types with different hydrodynamical and geomorphological characteristics and under identical climatic conditions , give place to find in Cuban territory vasts karst plains--the most extended karst type in the country--as well as hills , plateau and lower mountains karst types, stand out among the latter, the cone and tower karst , which , although appear like a typical in tropical regions , are not the most frequent in the Cuban territory.
Pan De Guajaibon Experimental Area
The Pan de Guajaibon massif is found belonging to the Northwestern extreme part of Sierra del Rosario , Pinar del Rio province. It is a 10km2 are a composed of two parallel carbonate massifs --Pan de Guajaibon and Sierra Chiquita-separated by an upper karstic valley. The highest point is Guajaibon peak 692m.a.s.l.
The experimental area is drained by the San Marcos river basin and has a pluvio-metric network with one pluviometer each 2km2 , two gauging stations installed in the massif springs and a standard climatic station for the air temperature and relative moisture records.
The annual and seasonal climatic mean values parametres and rainfall distribution for the observational period in the experimental area , can be seen in the Tab.1.
From a geological point of view , this is a very complex region , typical of the overthrust and nappes tectonical style and composed by a really lithological mosaic.
By using standard field methods and equipments, the hydrochemical analysis and water PH , temperature and electric conductivity , were measured and recorded.
From an hydrochemical point of view , all the massif circulation , waters are calcium-hydrocarbonate , except the waters from the allogenic feeding zone in the northeast of the massif, which have circulated on effusive-sedimentary rocks and are sodium-calcium-hydrocarbonate waters.
Taking into account the results of Pan de Guajaibon hydrological characteristics , it is possible to affirm that from a hydrodynamical point of view , it is a merokarst massif without deep circulation below base level. Due to the karst processes intensity and forms development , the massif runoff is fundamentally underground and it is integrated by two continuous karstic drainage systems-Ancon and Canilla.
The Canilla system feed is a mixture of autogenic and allogenic runoff , with circulation at the same level of the surface rivers Laslevel. Whereas the Ancon system feed is totally autogenic , with suspended circulation 60 meters above the base level.
By the means annual and seasonal discharge analysis registered during the observational period ( see Tab.2) , the major and more regular runoff regime was proved in Ancon system as compared with Canilla system. This is in correspondence with the physico-geographical conditions and rainfall distribution in both basins and consequently , the infiltration rate for the Ancon system was higher ( 70-85%) than for the Canilla system(35-40%).
The higher and more stable waters mineralization of the Ancon system than the ones of the Canilla is in function of the combined effect of some hydrodynamical, lithological and microbiological factors.
According to all above mentioned , the mean annual and seasonal karstic denudation values for the observational period (see Tab.3) are remarkably higher in the Ancon system than in the Canilla system (115-130 and 40-50m3/km3 year respectively).
It must be emphasized that the denudation process in Cuban tropical climatic conditions , is a continuous and seasonal uninterrupted process during all the year and keeps up practically the same intensity during the rainy season(60%) than during the less rainy seasons , in function of the homogeneous spatial and temporary rainfall distribution. It does not happen in temperate and polar latitudes where during the greatest part of the year the karstic processes have a lower dynamics or it is practically stopped.
The karst denudation values reported in Pan de Guajaibon massif for a complete five years hydrological cycle , give a reliable measurement of this process intensity in the tropical Cuban lower mountain karst.
During the Cuban-Bulgarian expedition GUASO'88 to the Guaso Plateau mountain karst , some investigations in the upper basin of Guaso and Bano rivers were developed , in function of the karst massif hydrodynamical characteristics and the preliminary evaluation of karst denudation process intensity.
The Guaso plateau is located at the North of the Guantanamo city , its area is approximately 320km2 with absolute altitude higher than 800 meters. It is a carbonate and intensive karstified massif with fundamentally autogenic feed , which occur practically by all the limestones surfaces , and peripherical flow concentration , basically southward to the Guantanamo valley.
From a geological point of view it is a complex area , where the Eastern Cuba Paleogeno tectonical-sedimentary changes regime are significantly marked by the temporary sedimentation succession of the effusive-sedimentary , carbonate , terrigenous and carbonate-terrigenous sequences.
The ultramafic and effusive sedimentary are the oldest rocks in the investigated area , which crop out in the northern massif slope and are covered transgresively by thick carbonate sequences of the Charco Redondo limestones formation , which are partially covered by carbonate and carbonate terrigenous sequences. More southward in the Guantaname valley, the limestones of Charco Redondo limestones formation , which are partially covered by carbonate and carbonate terrigenous sequences (Yateras and Maquey formations respectively). More southward in the Guantaname valley , the limestones of Charco Redondo formation continue toward the sea and are covered on the plain by the terrigenous sequences of San Luis formation.
For the hydrological characterization of the massif , the information from the pluviometric network and gauging stations of the Hidrometeorological National Service , installed in Guaso and Bano river basins , were utilized. Moreover ,during the expedition period two portable gauging stations were installed in the Guaso upper plateau river ponor and resurgence.
The hydrological information analysis and water balance results are summa-rized in the Tab.4. In the matter, the sudden diminution of the yield and effective infiltration values , detected from the comparison among the both Guaso upper basin gaugins station data , must be emphasized , as well as , the significant differences in the same parameters registered in the hyperannual data from Guaso and Bano lower basins gauging stations.
Following the above hydrological results and observations carried out in the Guaso plateau , different levels of superimposed drainage systems were found there , according to the local and intermediate baselevels relative position , defined for nonpermeable bed rocks or textural differences into the limestones and by the amplitude , frequency and areal extension of the drainage circuits.
Consequently , from a hydrodynamical point of view some merokarst areas have been found in the upper part of the massif. In the rest of the plateau area , the structural disposition of the Charco Redondo limestones and its southward continuation below the terrigenous sequences of San Luis formation , joint with a negative water balance detected in both basins, has allowed to confirm the holokarst character of the massif and the deep drainage occurrence and its circulation toward Guantanamo valley.
By using field experimental methods it was possible to obtain a quantitative correlation among precipitations, discharge, water mineralization and geochemical parameters. Thus the action of the tropical rain on the waters dissolution capacity was demonstrated.
The Guaso basin karst denudation values reported during the observational period (see Tab.5) , have been much more intensive for the first section of head waters zone over the ponor, than for the complete upper basin, including the second section from the ponor --to the Campanario cave resurgence. It is due to the fundamentally different hydrodynamic charactor in both sections , as well as other secondary factors such as: hydraulic slope, rock-water time of contact, karst form density etc.
The estimated karst denudation annual values for Guaso and Bano river basins are also presented in the Tab.5. As it can be expected, the Bano basin denudation values are much greater than the Guaso basin(62 and 28 m3/km2 year , respectively). It is due to hydrodynamical and hydrochemical factors , e.g. , high differences in the deep infiltration losts and in water mineralization values among both karstic systems.
According to the hydrodynamic behavior of the Guaso plateau , the annual denudation estimated data are not reliable, mainly in Guaso basin. For the reliable denudation measurement, further methods will be used there. However these values give a measure of the present karst denudation values in this Eastern Cuba lower mountain karst.
New Program: Zapata Basin
Unlike the researching program in hills and lower mountains karst areas , a new investigation program concerning to the process, dynamics and environmental changes in the tropical karst of Cuba , has been started on a plain karst region: Zapata basin, in the southern karstic plain of Matanzas province.
Zapata basin comprises all the south slope of Matanzas province. It is a complex open sea karstic aquifer system, developed fundamentally in carbonate and carbonate-terrigenous Miocene transgressive sequencies , which compose the major part of the emerged area of the Cuban archipelago.
The distinctive water circulation particularities of the Zapata aquifer system in relation to these kind of aquifers and its relatively easy hydrodynamical behavior , depend on the presence of the structural depression in the southern part of the basin , filled up by carbonate Pliocene-Pleistocene deposits , over which , the big marsh area of Zapata Swamp has been developed.
From a hydrodynamical point of view , it obviously is a holokarst basin with 150-200 meters of estimated karstification thickness , in which , some aquifer levels and not less than three superposed drainage systems are found , defined by textural differences into the limestones and frequently interconnected by really hydrogeological windows.
Interesting karstic processes of accelerated corrosion by mixed waters , saline effect and biochemical factors, occurred there , as well as the aquifer water overexploitation, uncontrolled waste waters inputs, agricultural intensive exploitation and other anthropogenic impacts,increase the sea waters intrusion and the aquifer contamination processes.
The development of an international investigation program in the Cuban plain karst areas, are very interesting from the scientifical and practical points of view , not only within Cuban boundaries, but also in all the Caribbean basin and Gulf of Mexico coastal region, which have had the same geological history and evolution from the Neogene and Quaternary and wherever , these kinds of karst plains , with similar hydrological and hydrodynamical characteristics can be found.
Tab. 1 Annual climatic mean parameters values for the obersavational period in Pan de
Guajaibon Experimental Basin and it’s comparison with the hyperannual standards
|Parameters Mean Values Hyperannual Standards Representativity (%)|
PRI---400 1770 1900 93
PTI---222 1790 1900 94
PRI---222 1650 2000 93
PRI---02 1779 1900 94
PRI---03 1871 2000 94
Temperature (°C) 24.5 23 106
Relative moisture (%)
7:00 Hs 90 95 95
13:00 Hs 75 70—75 100
Tab. 2 Water balance for the observational period in both karstic systems of Pan de Guajaibon experimental basin ( Mean annual and seasonal parameters )
|System Area (km2 ) Season Q (m3/s ) I (mm ) P ( mm ) IC ( % ) E ( mm ) Dry 0.071 217 760 29 543
Canilla 5.1 Rainy 0.175 545 1200 45 655 Annual 0.123 762 1960 39 1198 Dry 0.173 622 853 73 231
Ancon 4.35 Rainy 0.322 1176 1246 94 70 Annual 0.248 1798 2099 86 301
Guajaibon Dry 0.244 403 803 50 400
Massif 9.45 Rainy 0.497 835 1221 68 386 Annual 0.371 1238 2024 61 786
Q —debit ; I—infiltration ; P—precipitation ; IC—infiltration coefficient ; E—evapotranspiration .
Tab. 3 Mean annual and seasonal karst denudation values for a complete hydrological cycle in Pan de guajaibon experimental basin .
|System Area(km2 ) Season Q (m3 / s ) W ( MM3 ) Y ( l/s.km2 ) EC ( uS.cm-1 ) T( mg/l) AT (mg / l ) A (m3 ) D (m3 / km2 ) Dry 0.071 1.23 13.9 300 186 166 75 15
Canilla 5.1 Rainy 0.175 1.92 34.3 281 174 154 174 34 Annual 0.123 3.15 24.1 292 181 161 249 49
Dry 0.173 2.83 39.7 334 206 186 201 46
Ancon 4.35 Rainy 0.322 3.69 74.0 334 206 186 380 87
Annual 0.248 6.52 57.0 334 206 186 581 133
Guajaibon Dry 0.244 4.07 25.8 317 197 177 271 28
Massif 9.45 Rainy 0.497 5.61 52.5 308 191 171 542 57
Annual 0.371 9.63 39.2 313 194 174 313 85
W—Total runoff ; Y—Yield ; EC—Electric Conductivity ; AT , T –Mineralization .
Tab. 4 Hydrological information analysis and water balance of Guaso Plateau
|Detailed water balance of Guaso upper basin for the observational period (Jan. 20 –Feb. 8 , 1988 )
Area ( km2 ) P ( mm ) Q ( m3 /s ) Y ( l /s.km2 ) W ( MM ) R=iI ( mm ) IC ( % )
Guaso Ponor 36 83 0.965 26.8 1.67 46 55
Bano basin 93 83 1.192 12.8 2.07 22 26
|Estimated hyperannual water balance of Guaso and Bano river basin ( 1964—1987 ) .
A(km2 ) P(mm ) Q(m3 /s) Y(l/s.km2) W(MM) R=iI(mm) rI(mm) tI(mm) IC(%) E(mm)
Guaso basin 93 1700 1.17 12.6 36.9 397 453 850 50 850
Bano basin 71 1700 1.64 23.1 51.7 728 122 850 50 850
i I , rI , tI—Intermediate regional and total infiltration ; R—surface runoff .
Tab. 5 Chemical denudation of Guaso Plateau
|Guaso river basin karst denudation hyperannual values for Guaso and bano rivers.
A(Km2) t (days) Q (m3/s) Y(l/s.km2) W(MM) EC(uS/cm-1) T(mg/l) AT(mg/l) A(M3) D(m3/km2.t)
Guaso Ponor 36 20 0.965 26.8 1.67 280 173 153 102 2.8
Guaso Resurgence 93 20 1.192 12.8 2.07 317 197 177 146 1.6
|Estimated karst denudation hyperannual values for Guaso and Bano rivers.
System A(Km2) Q (m3/s) Y(l/s.km2) W(MM) EC(uS/cm-1) T(mg/l) AT(mg/l) A(M3) D(m3/km2.t)
Guaso 93 1.17 12.6 37 317 197 177 2609 28
Bano 71 1.64 23.1 52 377 234 214 4422 62
Guaso Massif 164 2.81 17.1 89 347 215 195 6904 42