| Abstrakt: |
One of the major environmental challenges facing the world today is land degradation and soil erosion, which pose a significant threat to the environment. Loss of top fertile soil will decrease the land's ability to produce, posing a threat to the safety of the world's food supply. Soil erosion is one of the pressing environmental problems in Thailand. This study aimed to identify soil erosion for prioritizing conservation measures and evaluate BMPs for reducing soil erosion using the soil and water assessment tool (SWAT) model in Si Satchanalai Sub-Watershed (SS-SW) in the lower watershed of the Yom Watershed, Thailand. The SWAT model was calibrated (2016 - 2018) and validated (2019 - 2021) using streamflow and sediment data in the SWAT calibration and uncertainty program (SWAT-CUP). The coefficient of determination (R2), the nash - sutcliffe efficiency (NSE), the percent bias (PBIAS), and the root mean square error-observations standard deviation ratio (RSR) values during flow and sediment calibration and validation periods ranged from 0.94 to 0.96, 0.82 to 0.91, -2.8% to 7.2%, and 0.28 to 0.42, respectively. The study indicates that SWAT is able to simulate streamflow and sediment with sufficient accuracy. The calibrated and validated SWAT model was used to evaluate the effectiveness of three best management practices (BMPs) against the baseline conditions (Scenario A) for reducing soil erosion, such as filter strips scenario (Scenario B), stone/soil bunds scenario (Scenario C), and reforestation scenario (Scenario D). The result indicated that about 69.44% of the watershed was identified as soil erosion, which experienced a sediment yield of 18.77 ton/rai/year. The mean annual sediment yield at the baseline Scenario A approximately was 14.05 ton/rai/year. The implementation of Scenario B, Scenario C, and Scenario D reduced the sediment yield by 8.42%, 38.90%, and 68.72%, respectively. At the SW levels, Scenario B, C, and D reduced the mean annual sediment yield from 1.5% (SW-2) to 12.30 (SW-11), 10.25% (SW-2) to 67.14 (SW-20), 28.64% (SW-1) to 68.89 (SW-21), respectively. Therefore, the study suggests implementations of Scenario C and D for effective soil erosion reduction in the study watershed and in other watersheds in Thailand in general which have similar environmental settings. [ABSTRACT FROM AUTHOR] |
