Assessment of Surface Runoff Potency under Tropical Environment for Soil and Water Conservation Planning

Department of Agricultural and Biosystems Engineering, Faculty of Agricultural Technology, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia.

^* Corresponding author: chandra.tep@ugm.ac.id

Abstract

Water is essential for living organisms, including crops. Its presence is a crucial factor for agriculture. Soil and water conservation is an effort to sustainably maintain the availability of water, thereby meeting the water needs of crops in the agricultural sector. This research aims to estimate the potency of surface runoff as a hydrological indicator of watershed critically for soil and water conservation purposes. A hydrological tank model was used to estimate surface runoff. The results showed a potential for surface runoff of approximately 133.82 mm/month, occurring primarily during the peak rainy season from December to April. Soil and water conservation (SWC) technology using water harvesting ponds (WHP) on farmland was proposed to store surface runoff. Data analysis indicates that the use of WHP provides significant benefits from environmental and economic aspects. Based on an average WHP storage capacity of 10 m³, approximately 40% of the total watershed area is required for constructing water harvesting structures to accommodate all surface runoff. Harvesting all surface runoffs increases the base flow during the dry season by 225.14 mm. This study serves as a valuable reference for soil and water conservation planning, particularly in tropical watersheds.