ABSTRACT Turkey Has a Coastal Line of 1200 Km Along the Mediterranean Sea
Total Page：16
File Type：pdf, Size：1020Kb
SEAWATER INTRUSION IN COASTAL AQUIFERS OF THE MEDITERRANEAN COAST OF TURKEY Gültekin Günay ABSTRACT Turkey has a coastal line of 1200 km along the Mediterranean Sea. At the coastal plains which are situated in the east-west direction along this coastal line seawater intrusion is observed. Among the coastal plains situated along .the Mediterranean, Dörtyol-Erzin, Mersin-Berdan and Efrenk plains, Silifke-Ovacık plain, Içel-Gilindire plain, Gazipa,sa plain, Finike-Kumluca plain and Demre plain, located from the east to the west, respectively, are the ones at which the problem of salinity is most frequently observed. In this article, the geo - graphical and socio-economic features of the mentioned plains, general problems in the coastal aquifers and the geology and hydrogeology of these plains are studied separately and the maps and cross-sections of the plains are presented. The present state of seawater intru - sion at the plains is also comprehensively studied. 265 TURQUÍA INTRODUCTION south direction. On the upper sections of these rocks, Cretaceous-aged limestones are placed. Geographical and Socio-economic The eastern part of the Dörtyol-Erzin plain Features is composed of serpentines extending from North The Mediterranean Region is situated in sou- to the South. Cretaceous limestones is located on thern Tur k e y . The total length of the coastal line is the serpentines. In the North and the Northwest of 1200 km. Along the coastal line, plains, at which the area, Miocene sandstones are observed. seawater intrusion is observed, are also located. In The alluvium is formed by very coarse grai- this present article, some of these plains will be stu- ned alluvial cones in the East, in the middle sand died with respect to their certain features. and gravel and towards the coast, fine grained The coastal section is generally an uneven material of sand and silt. The basalt eruptions has area. Highly elevated mountains with plains at their been started in Pliocene which is also continued slopes dominate the region. Majority of the popula- in Quaternary. tion in the region are agricultural workers and cities The study area has been undergone Caledo- like Adana, Mersin and Antalya are also industrial nian, Hercynian and Alpine orogenesis. At several areas. The total number of people who are settled times the study area has been uplifted, subsided, along the Mediterranean coast is 5 millions. Most folded or faulted. The basaltic eruption taken pla- of these people work on land and the rest are ce in Pliocene and Quaternary is caused of the employed in industrial and tourism sectors. change in the structure. The cretaceous limesto- nes and serpentines contain some amount of General Problems in Coastal Aquifers groundwater due to the existence of fissures and The most serious problem in the coastal sec- cracks. Also excessive replenishment is dischar- tion is seawater intrusion especially during the ged by means of springs. summer months, seawater intrusion increases due The favourable formations for groundwater to groundwater overpumping. As a result of the are conglomerates, basalts, sands and gravels. salinity, which develops in the alluvium aquifer, The basalts are encountered in the northwest of in some of the plains, wells that reach lower kars- the plain. tic aquifers are formed. Another serious problem Berdan Efrenk Plain: Sedimentary and in the coastal plains is the intrusion of seawater metamorphic rocks in the Mersin-Berdan and through drainage canals due to tidal effects. In Efrenk plains take over are whole area (figure 2). Adana plain this type of intrusion occurs at appro- Sedimentary rocks cover the north part of the ximately 30 km into the land. This intrusion cau- area. These rocks are; limestone, marl, sandstone, ses over-salinity in the plains. For the salinity in sandstone interbedded with clay, sandy limestone these plains to disappear, seawater intrusion ad marl, their ages are Tortonien of Miocene; should be hold back and then the soils should be Lower Miocene limestone and Palaeozoic crysta- rain-washed for at least 5-6 years. llized limestone. The metamorphic rock outcrops on a very little area and it is seen in the north part of the area on the north part of the area on the east GEOLOGICAL CONTEXT of Ziyaret mountain. The metamorphic rock is formed as clayey schist. The plain is a delta plain, Regional Geology of Coastal Areas which is collapsed and sedimented by alluvial material from the streams. Dörtyol-Erzin Plain The main streams of the area are Berdan At the Dörtyol-Erzin plain, (figure 1) the River and Deliçay, Efrenk and Mezitli Creeks. eastern section of the plain is constituted by ser- These streams form the delta. There is no impor- pentine rocks. These rocks stretch in the north- tant spring in the investigation area, but there is a 266 SEAWATER INTRUSION IN COASTAL AQUIFERS OF THE MEDITERRANEAN COAST OF TURKEY Figure 1- Hydrogeologic map of the Dörtyol - Erzin Plain. 267 TURQUÍA Figure 2- Hydrogeologic map of the Mersin - Berdan and Efrenk Plains. group of springs in the west of Berdan which is The trend of old geosynclines generally formed by the intersection of the topography and appear at continuous and high peaks. The old base the groundwater table. rocks is formed continuous and high peaks. The The water bearing formation of the area is old base rocks is formed by sedimentary rocks only the Quaternary’s sandy gravelly levels. The which can be found at the border of the plain or thickness of this formation is 200 m in Berdan under a thin alluvium layer. This old base rock and the aquifer is of free type near the lower generally trends in NE-SW direction. Although boundary of the forest and it is in artesian aquifer the appearance of the plain is due to tectonic ori- type towards to the seaside. The thickness of gin, it is also due to the erosion of soft sedimen- water bearing formation is 100 m in Deliçay pla- tary rocks of the old base. The water bearing for- ne and the aquifer is of free type. The thickness of mations in Ovacık area are mainly various limes- the water bearing formation is 10-80 m and it is tones and the alluvium. The drainage area of the spread over the left side. limestones are greater in comparing with the other formations. Ovacık Plain . The formation in the Ovacık plain (figure 3) Içel-Gilindire Plain . are the sedimentary rocks from Cambrian to Qua- The formation in the Içel-Gilindire plain ternary. Igneous rocks are not observed. Trans- (Gilindire, Sipahili and Büyükeceli plains) are gressions, at the beginning, seems to be move into the Palaeozoic complex series at the basement the places which being bended down. (micashist, ,seyl, limestone and undiff e r e n t i a t e d 268 SEAWATER INTRUSION IN COASTAL AQUIFERS OF THE MEDITERRANEAN COAST OF TURKEY Figure 3. Hydrogeologic map of the Silfke-Ovacñk Plain. Sñlñfke ve Ovacik Cñvari Jeolojñ Harñtasi. series) takes place. Over this basement com- Gazipa,sa Plain plex, there are Mezosoic limestone, Paleocene- Oldest formations in the investigation area Miocene limestone and at the plain there are (figura 5) are Devonien schist: clay schist, chlori- a l l u v i u m . de schist, micaschist and quartzite which are for- 269 TURQUÍA quartzite, and ophiolites. Their ages change bet- ween Palaeozoic and Mesozoic. Alakır Çayı Group outcrops in the north and northeast part of Kumluca district center. Th i s group is formed by limestone, radiolarite, ophioli- te and detritic rocks. These rocks in Mesozoic age. Çataltepe group outcrops in the north and west part of the Finike district center. It is usually formed by carbonate and layered rocks. This for- mation is in Mesozoic age. Neogene sediments which are formed or marl and clayey limestone interbeds, outcrop in the east of Salır Mountain. It is seen as flysch facies. The conglomerate which is under the allu- vium can be a Neogene sediment. Volcanic rocks are extrudes along the north- south directioned fault in the north of Kumluca district center and they are formed by serpentine and peridotite. Demre Plain The oldest formation of the investigation area is Mesozoic limestone (figura 7). This limestone is formed on the Eocene flysch as an overthrust. Besi- des that, (from old to young) Cretaceous limestones, Figura 4- Hydrogeologic map of the ñçel - Gilindire Plain. Eocene limestones, Eocene flysch and Neogene ming the foundation of the basin. Upon these for- marly limestone and conglomerates are covering this area. The Quarternary’s clayey, sandy and gra- mations stratigraphically follow rocks are velly alluvium is in the surroundings of Gölova, encountered such as Permian limestone; Neogene Karagöl, Avlan Lake and Kasaba, Akçay and Dem- conglomerate, clayey gravel, clay, Quaternary re plains. The alluvium is sandy and gravelly near clay, gravel, sands. the stream beds and clayey near Eocene flysch. Limestone and Schist forming Alanya mas- Akçay and Demre (between A l a k e n t - sif are folded and fissured by the Alpine tectonic Kö,skerler) plains are suitable for ground water. movements and highest places of the plain are Sandy and marly layers of alluvium contains formed by schist and limestones. ground water in these parts and in Elmalı (west part of Balıklar Mountain) Mesozoic limestones. Finike-Kumluca Plain The geologic units which show complex stra- tigraphy locate near the investigation area (figura 6). CHARACTERIZATIONS OF These formations are named Antalya Nappes and COASTAL AQUIFERS separated into three groups, Tahtalı Dag group, Alakır Çayı group and Çataltepe Group. Dörtyol-Erzin Plain Tahtalı Dag Group outcrops in the east part Dörtyol-Erzin plain extending between of the plain.