自然资源部岩岩溶动力学重点实验室

RECENT RESEARCH BY IGCP 299 PARTICIPANTS

1993-07-10KDL 1564

RECENT RESEARCH BY IGCP 299 PARTICIPANTS

 

ROUND TABLE ON SPACE AND SOLAR INFLUENCE ON THE ENVIRONMENT

Y.Shopov (Bulgaria)

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.

 

A NEW METHOD FOR DATING OF NATURAL MATERIALS WITH PERIODICAL MACROSTRUCTURE BY AUTHOCALIBRATION AND 1ST APPLICATION FOR STUDY OF THE SOLAR ACTIVITY IN THE PAST

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)

Introduction

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:

wpe1.jpg (2205 bytes)

where:
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).

Conclusions

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       SO       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 
________________________________________________________________________________

 

 

HYDROLOGY AND DYNAMICS OF THE TROPICAL KARSTIC PROCESSES IN CUBA

J.E.Redriguez and J.R.Fagundo (Cuba)

Abstract

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/kmyear respectively were reported in Pan de  Guajaibon massif. Same values in another validation karstic areas of the  country  have been determined.

Introduction

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.

Guaso Plateau

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/kmyear , 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 (%)
Precipitations (mm)

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(m/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