Modelling hydrologic dynamics of lower Seyhan Basin by SWAT model approach

The goal of this study is to simulate impact of landuse and agricultural activities by using Soil and Water Assessment Tool (SWAT) with daily flow out and nitrogen dataset to support and develop sustainable water use on the overall Lower Seyhan Basin. SWAT was run in the period of the 2011 to 2017 and the interaction between Agricultural practices and hydrologic processes was analyzed on the overall basin. The main input dataset for SWAT were climate data, soil map, land use map, management practices and digital elevation map at watershed scale. Calibration studies were carried out in test area (9 495 ha) where is located on the River Irrigation Association in Lower Seyhan Basin. On test area, Calibration Uncertainty Program (SWAT_CUP) was used for calibration and validation process by using 2-year (2009-2010) dataset of flow out and nitrogen (NO3 Out). In this process, Sequential Uncertainty Fitting (SUFI-2) approach was preferred on the basis of Nash-Sutcliffe coefficient of efficiency (NSE) and R2. The obtained parameters from nitrogen calibration study were used in the models of Four sub basins (Bebeli, Yemişli, Karagöçer and Baharlı) that are obtained by dividing Lower Seyhan Basin, which run for 2017, for validation. NSE /R2 values for Bebeli, Yemişli, Karagöçer and Baharlı respectively are 0.82/0.85, 0.72/0.75, 0.53/0.61 and 0.66/0.85. According to the validation results of Sub basins, nitrogen concentration in water successfully were modelled by SWAT model.