Application of SWAT model for spatial runoff analysis from land use change in Nam Mae Suai sub-watershed, Chiang Rai province | การประยุกต์ใช้แบบจำลอง SWAT เพื่อวิเคราะห์ปริมาณน้ำท่าเชิงพื้นที่ จากการเปลี่ยนแปลงการใช้ประโยชน์ที่ดินบริเวณลุ่มน้ำสาขาน้ำแม่สรวย จังหวัดเชียงราย
2024
Natee Sodchuen(Kasetsart University, Bangkok (Thailand). Faculty of Forestry) | Wanchai Arunpraparut(Kasetsart University, Bangkok (Thailand). Faculty of Forestry) | Venus Tuankrua(Kasetsart University, Bangkok (Thailand). Faculty of Forestry)
The Nam Mae Suai sub-watershed has water resource problems, including flooding and water scarcity every year. Consequently, the amount of water flowing into the Nam Mae Suai Reservoir may fluctuate due to land use changes in the past. Therefore, the Soil and Water Assessment Tool (SWAT) model was applied to assess the mean runoff and to analyze the water balance from the land use change effects from 2013 to 2018. The results showed that the SWAT model was effective in runoff assessment and water balance analysis for the Nam Mae Suai sub-watershed. The results of model calibration gave values for the coefficient of determination (R2) of 0.80, the Nash-Sutcliffe efficiency (NSE) of 0.76 and the percentage bias (PBIAS) of -9.2. It was found that between 2013 and 2018, there was a decrease forest area of 2.9 percent, converted to agricultural and residential areas, causing the average annual runoff to decrease by less than 1 percent. So, it can be observed that the amount of runoff during the dry period decreased by approximately 2 percent, especially at the end of the rainy season from October to December, due to decreasing rainfall, and reduction of forest areas into agricultural areas, causing water loss from evapotranspiration to increase by 2 percent. This causes the soil water storage and streamflow to decrease and the water yields also only slightly decreased. It can be concluded that the runoff volume and water balance of Nam Mae Suai sub-watershed slightly decreased from land use changes. (Overall decreased by no more than 2 percent).
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