[A-HW22] Material transportation and cycling in watershed ecosystems; from headwaters to coastal areas

[AHW22-P26] A comparative analysis in modeling surface runoff under climate and land use change in two catchments in Iran and Indonesia

*Sharif Joorabian Shooshtari¹, Shin-ichi Onodera², Yuta Shimizu³ (1.Department of Nature Engineering, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Iran, 2.Graduate School of Advanced Science and Engineering,Hiroshima University, 3.Western Region Agricultural Research Center, National Agriculture and Food Research Organization)

The specific objective of this study includes comparative analysis of the impact of climate and land use change on the surface runoff for two watersheds viz. Neka River basin (Iran) and Cimanuk watershed (Indonesia) using a SWAT hydrological model. The catchment in Iran is close to Caspian Sea and the Cimanuk catchment located in a coastal area, near to Java Sea. Land Change Modeler developed by IDRISI Selva applied to identify the trends in land use changes in the Neka River basin from 2010 to 2050. Three multispectral remote sensing dataset were used from the database of the US Geological Survey for the years 2002, 2011, and 2017 for the analysis of land use change in the Cimanuk watershed. Moderate (RCP4.5) and intensive (RCP8.5) emissions climate change scenarios were simulated using projections based on 17 CMIP5 climate models to assess changes in precipitation in the Neka River basin. Rainfall projection for long term (2075–2099) was analyzed using an Atmospheric General Circulation Model in Cimanuk catchment. The results revealed the reduction of the forest area by the increases in agricultural area and residential in two basins. Analysis of predicted surface runoff under land use change indicated an increase of 5.1% in the Cimanuk watershed from 2002 to 2017, and an annual increase of 5.5% in the Neka River basin. Changes in surface runoff due to climatic changes leads to increase by +6.1% (12.5%) under RCP4.5 (RCP8.5) scenarios in the lower part of the Neka River basin based on the inter-model average while a slight increase of 0.3% appeared in another basin. Land use change has greater impact than does climate change on variation surface runoff in the Cimanuk watershed, while climate change had more effects than those of land use change in the Neka River basin.