Watershed modeling and risk assesment of Ergene river basın

Abstract

Protection of water resources in terms of quality and quantity is one of the main challenges for the developed and developing countries. Especially, pollution caused by industrialization and agriculture makes difficult to manage water resources. Ergene Basin, which has been exposed to population growth, migration, industrial development and agricultural pollution since the 1980s, was the focus of this study. Hydrological characteristics of the basin can be modeled thanks to advances in geographical information systems, hydrologic and water quality models. In this study with using ArcSWAT, Ergene Basin was modeled with the combined effects of land use and climate. Additionally, the hydrology and water quality of the basin were evaluated by ArcSWAT according to future climate and land use change scenarios. In this context, the flow data of the İnanlı and Hayrabolu streams were used for calibration and validation process of the model and high degree of accuracy was obtained. Total nitrogen and phosphorus values of the model were compared with İnanlı water quality monitoring point values. Results of model revealed that it can be used for future scenarios of Ergene Basin. After this stage land use change predictions were calculated for Ergene Basin with using CORINE land use 1990, 2000 and 2012 which were obtained from European Environment Agency. In addition for the estimation of 2030 and 2050 land use maps, potential land use change map was created with CA_MARKOV analysis by using driving factors such as distance to city center, main roads and rivers. In order to examine the effects of climate change, precipitation and temperature data were created for Ergene basin according to RCP4.5 and RCP8.5 climate scenarios of Meteorology General Directorate. Generated future land use and climate data were used as input for the validated ArcSWAT model. The future flow and nutrient estimation of the basin were calculated and compared according to different scenarios. Also, Mann-Kendal, Rho-Spearman statistical tests were used to make inferences for the future from historical data. Additionally with ARIMA model, the trend towards future has been revealed. Total nitrogen and phosphorus values were compared with the ArcSWAT model outputs. To sum up, the current and future status of the region in terms of water flow quantity and quality is modeled with ArcSWAT by taking into account the land use and climate effects. This study was one of the rare studies in Turkey able to integrate climate variability and land use change on water resources.