Impacts of land cover/land use changeandrelationship of water budget components in Konya Closed Basin: Historical research and future perspective

Endorheic basins are very limited in terms of water resources due to the sensitive hydrological balance they have and the anthropogenic effects they are exposed to. As endorheic basins are generally found in arid and semi-arid regions around the world, their hydrology becomes more fragile under the effect of limited precipitation and high evapotranspiration. Konya Closed Basin (KCB) is a water-limited basin where agriculture is intensively done. In the KCB, which was determined as the study area, primarily using remote sensing data, land cover changes that occurred in the 2002-2019 period were tried to be determined. KCB water budget variation was investigated with Global Land Data Assimilation System (GLDAS) and Gravity Recovery and Climate Experiment (GRACE) datasets. In addition, the contribution rates of the total water storage anomaly components were calculated. The relationship between precipitation, which is the most important hydrological parameter that provides water input to the KCB, with the total water storage anomaly and its components has been examined. Monotonic and sub-trend analyzes of different hydrological parameters were performed. In line with the results obtained, it has been determined that the agricultural areas have an increasing trend throughout the study period. The effect of precipitation on the groundwater storage system was determined as 6 months. In addition, it was determined that the soil moisture storage anomaly (49.61%) and the groundwater storage anomaly (33.12%) are the two components of the total water storage anomaly with high contribution rates. It has been determined that the groundwater level has a decreasing trend in alluvial aquifers (150.75 mm/year) and predominantly limestone aquifers (78.55 mm/year). It has also been determined that precipitation and evapotranspiration parameters have a general increasing trend, but evapotranspiration has a more dominant increase trend compared to precipitation. As a result of examining the hydrological time series in terms of sub-trend, it was concluded that the drought that occurred in 2007-2008 was an important breaking point. For two different scenarios where the land cover is fixed and variable, the Mesoscale Hydrologic Model (mHM) used 10 flow observation stations in the KCB to validate. Accordingly, the warm-up period is 2002-2003, the calibration period is 2004-2015, and the validation period is 2016-2019. Evapotranspiration and groundwater level anomaly outputs of the mHM model, in which satisfactory results were obtained in the flow estimation, were evaluated. Accordingly, it was concluded that the actual evapotranspiration values of GLDAS were underestimated. However, it has been observed that the scenario where the land cover shows temporal variation is more successful in estimating the groundwater level anomaly.