Burdur - Ağlasun Havzasının Hidrojeoloji İncelemesi

Abstract

Burdur – Ağlasun Havzasının jeolojik ve hidrojeolojik özelliklerini aydınlatmak amacı taşıyan bu çalışma; İstanbul Teknik Üniversitesi Fen Bilimleri Enstitüsü, Uygulamalı Jeoloji Anabilimdalı’nda Yüksek Lisans Tezi olarak hazırlanmıştır. Çalışma alanı 1/25.000 ölçekli topoğrafik haritada Isparta M 24 c2, c3; M25 d1, d2, d3, ve d4 paftaları içinde kalmaktadır. Saha çalışmalarında bölgenin 1 / 25.000 ölçekli jeoloji haritası revize edilmiştir. Jeoloji haritasının hazırlanmasında 1 / 25.000 ölçekli topoğrafik haritalar, jeolog pusulası, jeolog çekici, ve GPS kullanılmıştır. Saha çalışmalarında özellikle bütün bölgenin jeolojisi araştırılmış, birimlerin formasyon sınırları belirlenmiş, mevcut birimlere ait fotoğraflar çekilmiş ve yorumlamaya gidilmiştir. Arazi ölçüm ve gözlemlerinden faydalanılarak bölgenin sistematik jeolojik kesitleri hazırlanmıştır. Bölgede yer alan kaya birimleri allokton ve otokton konumlu birimler olmak üzere iki grup altında toplanmıştır. Otokton Birimler yaşlıdan gence doğru Erenler Kireçtaşı, Yazır Formasyonu, Ağlasun Formasyonu ve Alüvyondan oluşmaktadır. Bölgede Allokton birimler olarak Akdağ Kireçtaşı ve Ofiyolitli Karmaşık bulunmaktadır. İnceleme alanında bulunan Ağlasun meteoroloji istasyonuna ait çeşitli parametreler ve hidrolojik ölçümler değerlendirilerek Ağlasun Havzası için su bilançosu hazırlanmıştır. Havzada hesaplanan toplam beslenim 25,2 x 106 m3/yıl ve toplam boşalım 32,0 x 106 m3/yıl olarak hesaplanmıştır. İnceleme alanında litolojik ve yapısal özellikleri göz önünde tutularak birimler; boşluklar, boşlukların boyutları, boşluklar arası ilişkiler ve bu ilişkilerin derecesi gibi yeraltısuyunu geçirebilme ve iletebilme özelliklerine göre farklı hidrojeolojik özelliklere sahip olan ortamlara ayrılmıştır. Çalışma alanında yer alan jeolojik birimler fiziksel ve hidrojeolojik özelliklerine göre Pekişmemiş Formasyonlar (Yaygın-zengin akiferler, Bölgesel ilişkisiz (yerel) akiferler) ve Pekişmiş Formasyonlar (Bölgesel-ilişkisiz (yerel) Akiferler, Zayıf akiferler, Çok zayıf akiferler) olmak üzere gruplara ayrılıp, değerlendirilmiştir. Bu bilgiler ışığında bölgenin hidrojeoloji haritası yapılmıştır. Çalışma alanında bulunan akiferlerin hidrolojik parametrelerini (Transmisibilite ve Hidrolik iletkenlik) belirlermek amacı ile sondaj kuyularında yapılan pompaj deneylerinden elde edilen zaman-düşüm değerlerinden yararlanılmıştır. Hidrolik parametrelerin hesaplama yönteminin seçiminde öncelikle veri analizi yapılarak kuyuların dengeli rejime ulaştığı tespit edilmiştir. Dengeli rejim için geçerli olan Dupuit formülleri kullanılarak akifer parametreleri belirlenmiştir. Ayrıca pompaj deney verilerine ulaşılmayan kuyularda statik-dinamik seviyeler-debi ve akifer kalınlığı belirlenmiştir. Bunlardan ampirik yöntemlerle hidrolik parametreler hesaplanmıştır. İnceleme alanında yeraltısuyu kalitesini belirlemek amacı ile bu çalışma kapsamında temsili noktalardan alınan su örneklerinin analizlerinden ve sondaj kuyularının açıldıkları tarihlerde yapılan kimyasal analiz sonuçlarından yararlanılmıştır. Kimyasal analiz sonuçları kullanılarak hidrojeokimya haritası oluşturulmuştur. Ayrıca yeraltısuları içilebilirilik ve çeşitli kullanılabilirlik amaçlarına yönelik (Piper, Scholler ve Scholler içilebilirlik diyagramları; Wilcox ve ABD Tuzluluk laboratuvarı) göre sınıflandırılmıştır. Piper diyagramına göre bölgedeki sular genel olarak Ca-HCO3 tipi sular sınıfındadır. Bölgedeki suların sulamaya uygunluğunu belirlemek amacıyla ABD Tuzluluk laboratuarı ve Wilcox diyagramlarına göre sınıflandırma yapılmıştır. ABD Tuzluluk laboratuarı sınıflamasına göre; çalışma alanında bulunan yeraltısuları C1S1, C2S1ve C3S1 sınıflarındadır. Wilcox diyagramı sınıflamasında ise; çalışma alanındaki kaynaklardan alınan sular ‘çok iyi sular’ ve ‘iyi kullanılabilir sular’ sınıfındadır.

This study has been prepared as master of science thesis to clarify geological and hydrogeological characteristics of Burdur - Ağlasun Basin in Applied Geology Engineering Department of the Institute of Science and Technology of Istanbul Technical University. The study area is located in the so-called Isparta Angle, in the SW Turkey.1:25,000 scaled Isparta M 24 c2, c3, M25, d1, d2, d3, and d4 sheets were used . The study area is in the south east region of Burdur. As is known, nativ and foreign geologists have been investigating on the SW Anatolian since very early ages. The completion of the studies conducted so far and the accomplishment of incomplete studies display the significance of the issue. In this study, a hydrogeological investigation of Aglasun Basin (Burdur) and surrounding area has been performed. The obtained results were given on related tables and charts.In this study, it has been investigated as detailed geological, hydrological and hydrogeological features of Aglasun Plain which has semi-closed basin properties. During the field study, 1/25 000 scaled geological map of the region has been revised. In order to prepare the geological map, 1/25 000 scaled topographic maps, geological compass, geologist hammer and GPS is used. The geology of the whole region was investigated by field studies. The formation of boundaries were determined, also the photographs of the existing units were taken during this stage and interpreted. Within the scope of this study, the previously-conducted General Geology data of a region including the Aglasun Basin have been transferred to the digital medium by using Arc Map program. Systematic geological cross-sections of the region were prepared by using field measurements and observations for the Aglasun Basin. In the research, the geological units were grouped into two parts : autochthonous and allocthonous. These parts were presented in a 1 / 25 000 scaled geological map. Autochtonous Units are: Erenler Formation, Yazır Formation, Aglasun Formation, and alluvium. Allocthonous Units are : Akdag Formations and Ophiolite Complex. In the research area. The oldest rock of the autochthonous units is Erenler limestone of Cretaceous. This unit is overlain disconformably by Yazır formation of Aquitanian and its main lithology is reefal limestones. This formation is overlain by comformably by Aglasun formation of Burdigalian. Aglasun formation consists mainly of sandstone and shale. In the Middle Miocene, Akdag limestone unit and ophiolitic melange are thrusted and overlies tectonically onto Aglasun formation. The ophiolithic melange and Akdağ limestone units (Jurassic-Cretaceous) are the allochthonous rocks in this region. The Quaternary alluvium deposits are the youngest units of the study area. Allochthonous rocks were primarily emplaced in the region during Late Cretaceous to Early Paleocene period. All these units are covered by Quaternary alluvial deposits.This event is the most important tectonic feature in the region and this resulted of many folds and faults. In the study area, the common tectonic structures such as reverse or overthrust faults and fold axis are extending along the NW-SE direction. On the other hand, the dominant normal faults and fracture systems are trending along the NE-SW direction. It is possible that all these structural features in this region resulted under the NE-SW compressional forces, and NW-SE tensional forces. According to various parameters and hydrological measurements from Ağlasun Meteorological Stations in the study area, groundwater budget was calculated for Aglasun Basin.The study area covers an area of 93 km2 with an annual precipitation of 718,3 mm. The total estimated recharge of the basin is 25,2 x 106 m3 per year and discharge is calculated as 32,0 x 106 m3 per year. Taking into consideration lithological and structural characteristics in the study area, the units are divided into different hydrogeological areas according to the characteristics such as pores, pore sizes, voids, the degree of effective permeability and hydraulic conductivty. Geological units in the study area, based on their physical and hydrological characteristics, are grouped as unconsolidated formations (common - rich aquifers, unrelated to regional (local) aquifers), and consolidated formations (Regional - unbound (local) aquifers, aquifers are weak, very weak aquifers) to be evaluated. Hydrogeological map of the region were made in the light of this information. The time-drawdown values obtained from the pumping tests were used to determine hydraulic parameters (transmissibility and hydraulic conductivity) of the aquifers in the study area. Before selecting the calculation method, hydraulic parameters of wells were found to be steady state regime. Using Dupuit steady state regime formul, aquifer parameters were determined. In addition, wells without pumping test data, their static and dynamic levels and aquifer thickness of the hydraulic parameters were determined and calculated using empirical method. According to these methodological findings, transmissibility and permeability were calculated. The groundwater quality in the different aquifers was described by chemical analyses of the water obtained from springs and wells. Using these data an attempt was made to present a synopsis of the hydrochemical conditions in the investigated area.Water samples from the wells and springs were collected at June-July and October of 2012. In order to find out the hydrogeochemical features and groundwater quality and groundwater samples taken from representative locations in the Aglasun plain were analysed. In-situ analyses such as T, pH, and electrical conductivity have been performed during field studies. In order to represent aquifer charactersitic, samples obtained from springs and wells within the research area from 13 locations, have been examined. The groundwater have pH values ranging from 7 to 8.5, electrical conductivity changes 191 μs/cm (EK-6) ile 980 µs/cm (K-10). Moreover, water samples have been analysed for their anions, cations and some trace element contents. Hydrogeochemistry map was constructed by using the results of chemical analysis. Furthermore, hydrochemical map gives an insight in the quality of water in the investigation area. To determine the quality of the groundwater, results of chemical analysis were used by using groundwater samples and boreholes in the studied area. According to the chemical analysis results Wilcox, USA Salinity Laboratory, Piper and Schoeller Diyagram has been used and classified. Hydrochemical analysis results of water are evalatued using Piper diagram and water types are determined. Piper and Schoeller Semi-logaritmic diyagrams are both used in order to specify the dominant lithology in the formation chemical composition, and to classify water samples with respect to their chemical composition. Results indicate that they generally have Ca>Mg>Na>K and HCO3> SO4>Cl anions and cations which show that carbonate rocks are dominant in the formation of chemical composition. The groundwater in the studied area are of calcium bicarbonate type. According to Schoeller diyagram which was made as a result of the chemical analysis of the samples which were taken from the sources in the investigation area, sources are same origin. In the region, in order to determine the suitability of water for irrigation U.S. Salinity Laboratory and Wilcox diagrams are used. In respect to Wilcox classification, water from the resources are grouped as very good-good. As to USA Salinity Laboratory they are grouped as C1S1, C2S1 and C3S1.