Effect of Land Use/Land Cover Maps on CN Method: Case Study over Kahramanmaras

The impact of Land Use/Land Cover (LULC) data obtained from various spatial resolution satellites on the distribution of the Curve Number (CN) across Kahramanmaras using the Soil Conservation Service (SCS)-CN technique was investigated in this research. This study aimed to examine the effect of LULC on runoff due to increasing urbanization in the last century and the conversion of forest areas to agricultural lands. CORINE data with a spatial resolution of 100 m, and Sentinel-2A data with spatial resolutions of 10, 20, and 60 m were utilized in the analysis. The results reveal that only the average CNs of the products are in close proximity, while there are significant discrepancies in the CN variation over the maps as the spatial resolution increases. The Sentinel-2A satellite findings revealed higher CN values compared to the CORINE dataset over the study area where three geographical regions, namely the Mediterranean, Eastern Anatolia, and Southeastern Anatolia. Additionally, the results show that an increase in urbanization triggers surface runoff potential and reduces it in agricultural and forest areas in the city. Thus, the updated and higher spatial resolution of LULC promises accurate flood forecasting and/or more scientific potential drought estimation as well as other hydrological applications.