ECOLOGICAL PROBLEMS OF KARST WATERS CAUSED BY OVEREXPLOITATION AND CONTAMINATION On the example of North-East Bulgaria ERB-CIPA-CT93-0139 Project, coordinated by A. Pulido-Bosch, Professor of Hydrogeology University of Granada (Spain) This book is co-authored by A. Pulido-Bosch1, M. López-Chicano1, M. Machkova2, B. Velikov3, D. Dimitrov2, P. Pentchev4 and J.M. Calaforra5 1. University of Granada, Spain; 2. National Institute of Meteorology and Hydrology, Bulgaria; 3. University of Mining and Geology, Sofia; 4. Hydrocomp Ltd., Bulgaria; 5. University of Almeria, Spain. November 1997 I ACKNOWLEDGEMENTS The present study has been carried out within the framework of the program COPERNICUS, project ERB-CIPA-0139, financed by the European Community. In addition, part of the work falls within projects AMB92-0211 and AMB95-0493, financed by the CICYT (A. Pulido-Bosch, J.M. Calaforra, M.L. Calvache and M. López-Chicano). © Copyright ISBN II PREFACE This book describes the studies carried out by four research teams over a period of three years within the framework of the COPERNICUS Programme, contract CIPA-CT93-0139. It is intended to cover the many and varied field and laboratory activities undertaken and their subsequent analysis, including an initial in-depth interpretation of the great quantity of data obtained from the numerous field trips. In addition to the intensive contributions of each and every one of the team members, active collaboration was also provided for the duration of the project by a series of persons and/or consulting companies to resolve particular problems or assist in the acquisition of certain data. The study area, the Dobrich region, comprising some 4600 km2, presents a wide range of hydrogeological problems of both scientific and immediately practical interest. During the first year of activity, it was found necessary to establish the project goals focussing our attention on two pilot areas, one inland and the other on the coast. This enabled resources to be concentrated in a more rational and realistic way. At all times we enjoyed the active collaboration both of the local authorities - town mayors and staff of the water-supply services - and of numerous resorts and organisations of groundwater consumers within the study area. The local press was always present at acts held to present our project and provided objective and thorough reporting of our activities. This was a factor favouring the subsequent field trips made during the first and second years. On this first page, we wish to express our gratitude to all the above, individuals, organisations and the press, for their great assistance, without which the project would have had serious difficulties in reaching a satisfactory conclusion. Finally, we should make it clear that some aspects and partial results have been published in Journals and/or at Congresses; many more are currently under preparation for submission to various specialized Journals. Among these latter are Hydrogeology Journal, Revista de la Sociedad Geológica de España, Geology and Mineral Resources, 5th International Symposium on Karst Waters and Environmental Impacts (Antalya), 5th International Conference on Developments in Hydrogeology of Mountain Areas (Stara Lesna), TAHICU’96 (Cuba), XXVII IAH Congress on Groundwater in the Urban Environment (Nottingham). Other, already completed, studies have been submitted to Journals such as Journal of Hydrology, Comptes Rendus de l’Académie des Sciences de Paris, Hydrogéologie, Hydrological Sciences Journal. Almeria, Spain, November 1997 Antonio Pulido-Bosch Professor of Hydrogeology III RESEARCH TEAMS Four teams were responsible for carrying out this research project, assisted by certain collaborators, details of whose contributions are given below. Spanish team (University of Granada) * Prof. Dr. Antonio Pulido-Bosch, team leader, currently at the University of Almeria * Dr. Manuel López-Chicano, senior researcher * Dr. Jose Maria Calaforra, senior researcher (University of Almeria) * Dr. Maria Luisa Calvache, senior researcher We were assisted by Dr. Ignacio Morell (University of Castellon, Spain), who participated in two field campaigns (summers of 1995 and 1996). Bulgarian teams: + National Institute of Meteorology and Hydrology - Forecasting Department * Dr. Marta Machkova, senior researcher. Team leader * Dr. Dobri Dimitrov, senior researcher * Miroslava Ilieva, technical assistant * Yordanka Berova, technical assistant * Valentin Mironov, technical assistant, NIMH branch Varna. The following also made valuable contributions to the project: * Makroukhi Gyulian, chemist. Water Supply Service of Dobrich. * Ivan Stoikov, hydrogeological engineer. Water Supply Service of Dobrich. * Assen Lichev, hydrogeological engineer, from the Ministry of Environment. * Dr. Tsvetan Tsenov, senior researcher, leader of the tracer group, Georedmet Ltd. + University of Mining and Geology * Dr. Borislav Velikov, senior researcher. Team leader * Dimitrinka Dimitrova, technical assistant * Radka Takeva, technical assistant + Hydrocomp Ltd. * Dr. Pavel Pentchev, senior researcher. Team leader * Raina Angelova, researcher * Angelina Petrova, researcher * Georgi Mihov, technical assistant * Mariana Tchvetkova, technical assistant The following also made valuable contributions to the project: * Stanislav Kovatchev, researcher UMG, Department of Hydrogeology * Bojan Tonev, researcher, Geozashtita Ltd. Varna * Petar Stephanov, researcher UMG, Department of Geophysics * Dimo Trifonov, researcher. Water Supply Service of Dobrich. IV PART I.- GENERAL INTRODUCTION V 1. OBJECTIVES In the last few decades, the water quality of the karstic aquifers in Bulgaria, and especially in the NE region of the country, has deteriorated significantly as a consequence of agricultural and industrial activities. There is also a possible process of seasonal overexploitation of the aquifers, together with the tendency of a decreasing annual amount of precipitation. For all of these reasons, problems of nitrate pollution have appeared, as well as the probable beginning of seawater intrusion and groundwater depletion. The carbonate aquifers are almost the only source of fresh and drinking water in northeastern Bulgaria, and thus the present study is intended to provide an updated overview of the hydrogeological conditions of the two principal aquifers in the region. One of these aquifers is unconfined and shallow (Upper or Sarmatian Aquifer) and the other is confined and deeper (Deep or Valanginian Aquifer). These two aquifers are described separately. The main objectives of the study are to identify the hydrodynamic and hydrochemical conditions, and the processes of pollution, overexploitation and seawater intrusion in the two main karstic aquifers of the region, wich are heavily influenced by human activities. A better understanding of present conditions and of the reasons for the worsening of water quality and quantity in the most unfavorable areas are required in order to propose and implement measures for restoring and improving groundwater resources. 2. CHARACTERISTICS OF THE STUDY AREA AND PREVIOUS RESEARCHS The study region, with a surface area of some 4600 km2, is located in the NE of Bulgaria, between the geographical coordinates 27º 32' to 28º 42' longitude E and 43º 22' to 44º 00' latitude N. The geographical and political boundaries are: to the north, the border with Rumania; to the east and southeast, the Black Sea; to the south, the Batova River valley; and to the west, the Suha River valley (Figure 1). The most important cities within the area are: Dobrich, Balchik, Kavarna, General Toshevo and Shabla. As Dobrich is situated in the central sector of the study region and is one of the major administrative centres, we refer to the study area as the Dobrich Region (Dobrudja). Photo 1: View of the downtown section of Dobrich. From an economic point of view, this region is predominantly agricultural; it is the primary producer of wheat and corn in Bulgaria. The area under irrigation forms a relatively small part of the total study area. In addition, livestock installations are numerous, with pig farms predominating in the greatest concentration of the entire Balkan Peninsula. Most industrial activity is centred around the city of Dobrich, although there is also industry in Balchik and Kavarna. The coastal sector bordering the Black Sea registers a relatively high level of tourism, mainly domestic; there is substantial use of numerous spas supplied with thermal waters from the Deep Aquifer. Figure 1. Location of the study area. The first studies to characterize the hydrogeology and hydrochemistry of the region date from the 1970s and mainly consider the Upper Aquifer (Raykova and Danchev, 1972; Antonov, 1973; Antonov and Danchev, 1980). Later works provide VI hydrogeological descriptions of the principal productive levels of the region (Upper, Deep and other Aquifers), providing data concerning the hydrogeological and hydrogeochemical properties as well as values of hydraulic parameters (Danchev et al., 1981). More recently, an analogic electric model (R-C) was made for the Upper Aquifer to estimate the hidden or less visible discharge (Betsinski et al., 1990). In the late 1980s and early 1990s part of the Bulgarian team responsible for the above project carried out a further study to identify the hydrogeochemical processes underlying the interactions between water and carbonate rocks in the aquifers of the region (Velikov, 1985, 1991, and Velikov et al., 1986, 1989) and to