Hydrogeological investigation of Hasanlar dam basin

In this Graduate Degree thesis study it is aimed to investigate the geological, hydrological and hydrogeological properties of the Hasanlar Dam Basin and its close surrounding within the scope of the Geological Engineering program of Istanbul Technical University, Institute of Science, Technology and Engineering. The area of investigation is within the boundaries of the Yığılca district of Düzce province, located in the Western Black Sea region. To be more specific the study area is in frontiers of the F 26 C3, F 26 C4; F 27 D3; G 26 A1, G 26 A2, G 26 A3, G 26 A4; G 26 B1, G 26 B2, G 26 B3, G 26 B4; G 27 B2 and G 27 D4 1/ 25.000 scale topographic maps. During the field investigations coordinates, strike and dip of the layers measured by instruments (Brunton geological compass, Etrex gps etc.). The Geological map of 1/ 25.000 scale revised with the field studies. The data obtained from previous studies were also taken into consideration in terms of clarification of formation boundaries. Subsequently geological cross sections were prepared. The Hasanlar dam basin is located within western Pontid zone. The Yedigöller Formation underlying at the bottom is mainly consist of metavolcanite, metagranitoid, migmatite, amphibolite, gneiss, marble and schist age of Precambrian. The Lower Ordovician aged Kurtköy Formation, consisting of sandstone, mudstone and conglomerate comes with angular unconformity over the Yedigöller Formation. The Ereğli Formation, transitional with Kurtköy Formation from bottom and Yılanlı Formation from top is consist of consecutive sandstone, shale and limestone units. The Yılanlı Formation, composed of limestone, dolomitic limestone and dolomites is of Middle-Upper Devonian-Lower Carboniferous age. Triassic-Permian aged Çakraz Formation comes with angular unconformity over the Yılanlı Formation, is composed of sandstone, mudstone and conglomerates. Consisting of Cretaceous aged units such as conglomerate, sandstone, siltstone, marl, limestone, marble, granite, gabbro and serpentinite Abant and Akveren Formations demonstrates angular unconformity each other. The Yığılca Formation formed from aglomerate, basalt and different volcanic origin rocks during volcanic activities in the Eocene period is transitional with Çaycuma Formation consisting of limestone, tuffite, marl-level sandstone, siltstone and claystone units. Quaternary aged units are slope rubble and alluvium. They are formed as a result of erosion and transportation of river sediments. Trustworthy and regular measured data's gathered from the State Meteorological Stations in the study area were evaluated for the groundwater budget estimations of Hasanlar Dam Basin. Arid and rainy periods of the region determined by the average precipitation and deviation rates. Syn-precipitation curves plotted with ArcGIS software used to calculate total and average precipitation rates for Hasanlar Dam Basin. Moreover, the same curve method applied to estimate total and average real evapotranspiration rates which previously gathered from 5 different State Meteorological Stations and calculated by PENMAN method. Subsequently, flow rate obtained from difference of precipitation and real evapotranspiration compared with ratio compiled from Flow Observation Stations. Total recharge and discharge rates acquired due to mentioned calculations. Structural and hydrogeological features of the lithological units in the study area are evaluated and classified according to possessiveness and transmission characteristics of groundwaters. Unconsolidated Formations (wide-rich aquifers, regional unallied-local aquifers) and Consolidated Formations (wide-rich aquifers, regional-unallied local aquifers, poor aquifers, very poor aquifer). The Hydrogeological map is prepared in the frame of this information. Samples gathered from 12 locations where the region could be represented. In- situ measurements such as temperature, hydrogen ion concentration, electrical conductivity performed by portable devices. Furthermore, comprehensive analysis of water samples took place at TUBITAK MAM laboratories. Hardness, SAR, sodium ion rate, pH, electrical conductivity results were taken into consideration in the assessement of general chemical properties of groundwaters. The anion, cation, minor element and heavy metal contents of the samples are taken into account for hydrogeochemical evaluation. The values mentioned above are drawn in the form of graphs to reveal types of waters, relations with rocks, mixing problems, grouping and spatial changes. Piper, Schoeller, Wilcox and US Salinity Diagrams prepared to determine the quality of the waters according to their intended use. Moreover, from the Piper diagram prepared to classify the groundwaters, the samples taken during arid and rainy periods are in the class of Ca-HCO3 water type. This result in the Piper diagram coincides with the result in the Schoeller diagram. In this basin it showed that the carbonate rocks are effective in the chemical composition of waters. It is possible to obtain information through the Schoeller diagram whether the examined samples are of the same origin and the possible formations that groundwater contacts. According to Schoeller diagram the cation values of the water samples are in Ca> Mg> Na + K and the anion values are in HCO3> SO4> Cl order. However, the results of spring number 2, located at southern part of Şaban- Gökçeagac highway shows Ca> Na + K> Mg and HCO3> Cl> SO4 trend. Also, the water samples were evaluated in terms of drinking and irrigation. Samples were evaluated in comparison with TSE-266 and WHO drinking water standards. The results of the analysis of water samples taken during arid and rainy periods illustrates that all of the samples are below the permissible rate. Only the analysis results of Hasanlar Cuma Camii site sample demonstrates that the value of Manganese was above the maximum permissible level of both TSE-266 and WHO. In order to determine whether the spring waters in the study area are suitable for irrigation, the chemical analysis results of the water samples taken from the region were drawn on Wilcox and USA Salinity diagrams. It has been determined in Wilcox diagram that all of the water samples taken during arid and rainy periods from the springs in the study area are in "Very Good" type. It has been also determined in US Salinity diagram that all the samples are in C2S1 class except spring number 7, Dutlar village which is in C3S1 class. However, as a result, all water samples taken from Hasanlar dam basin are suitable for irrigation.