Drought analysis with SWAT hydrological model

Drought is one of the most significant effects of climate change. Drought has no time or space limits, but it is predicted that if action is not taken, it would drastically limit the variety of products and have a detrimental impact on socio-economic life in the future. The scope of this study, Denizli-Civril-Baklan Plain was modelled hydrologically with SWAT and then meteorological, agricultural, and hydrological drought indices were calculated and detailed drought analysis was performed with DMAP programme. Landsat-8 satellite images, CORINE land use map, FAO soil map and climate data were adapted to the study area and used as input to the SWAT model. The period between 1984-2021 was selected as the study period and potential evapotranspiration (PET), soil moisture, stream flow and other values were calculated by SWAT model. The indices used for meteorological drought calculation are SPI, RAI, PN, PDSI. ARI and SMDI indices were used for agricultural drought, and SWSI index was used for hydrological drought. The fact that the average annual potential evapotranspiration (1208.9 mm) is greater than the average annual precipitation (525.6 mm) indicates that the climate is generally drought and there is a need for irrigation. According to the model, it was determined that water stress was experienced in an average of 83 days in a year. In PDSI drought index, droughts of longer periods were observed compared to other meteorological drought indices. PDSI differs from these indices by using PET data in addition to precipitation. When all indices are analysed on a monthly basis, it is determined that the index with the highest number of dry days between 1984-2021 is PDSI (9741 days) and the index with the lowest number of dry days is SPI (2003 days). When all indices were analysed on annual basis, it was found that the index with the highest number of dry years was PDSI (31 years) and the index with the lowest number of dry years was SWSI (4 years). In this study, it is aimed to analyse the drought in the region in detail and to enlighten future studies. KEYWORDS: Drought, Climate Change, SWAT, Meteorological Drought, Agricultural Drought, Hydrological Drought, DMAP