|NUT, NARETH - Royal University Of Agriculture|
|MIHARA, MACHITO - Tokyo University Of Agriculture & Technology|
|JEONG, JAEHAK - Blackland Research And Extension Center|
|NGO, BUNTHAM - Royal University Of Agriculture|
|PRASAD, VARA P. - Kansas State University|
|REYES, MANUEL - Kansas State University|
Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2021
Publication Date: 8/18/2021
Citation: Nut, N., Mihara, M., Jeong, J., Ngo, B., Sigua, G.C., Prasad, V.V., Reyes, M.R. 2021. Land use and land cover changes and its impact on soil erosion in Stung Sangkae catchment of Cambodia. Sustainability. 13(16):9276. https://doi.org/10.3390/su13169276.
Interpretive Summary: In Cambodia, the forest cover has declined dramatically in the last few decades, while the research on soil erosion loss caused by land use-land cover (LULC) changes is limited, particularly in the Stung Sangkae catchment. While there is little research on soil erosion reported to date, most of the soil erosion and sediment studies were conducted at a large river basin scale such as the Mekong River Basin or the Lower Mekong Basin. Thus, the overall goal of this study was to evaluate the LULC changes and its impact on soil erosion in Stung Sangkae catchment in the years 2002 and 2015. The specific objectives of the study were to: (1) estimate the magnitude of annual soil erosion and its spatial distribution in the catchment; and (2) evaluate how land use and land cover types contributed to soil erosion in the catchment. Over the years, there was extensive soil erosion of very low to moderate severity rates ranging from 0.2 to 7.1 ton per hectare per year (t/ha/y). The highest erosion rates of 14.3 to 62.9 t/ha/y were found in parts of the upland of the Stung Sangkae catchment, mainly due to steep slopes, high rate of erosion, and degradation of the vegetation. Between 2002 and 2015, considerable changes in soil loss rate were observed in agricultural land. The forest lands decreased significantly during the invested period, particularly a massive change of deciduous and mixed forest, which was converted to agricultural land, rice paddy fields, and other types of land use. Therefore, it is necessary to integrate protection measures at farm level and target areas of high risk of erosion, mainly the degraded lands along the steep slopes, to limit the conversion forest areas for agriculture and minimize the rate of erosion where the land is bare or with low vegetation cover. Some of the recommended measures to prevent soil erosion includes on-farm conservation agriculture practices, water conservation and management, agro-forestry practices, vegetation cover restoration, and terracing. Future soil erosion assessment work in the study area should examine soil loss due to gully erosion, which is not currently possible using the Revised Universal Soil Loss Equation (RUSLE) model. Additionally, calibration of the RUSLE results through field experiments helps to verify the accuracy of the estimated soil erosion in the study area.
Technical Abstract: The agricultural expansion and urban development without proper soil erosion control measures have become a major environmental problem in Cambodia. Due to a high population growth rate and increased economic activities, land use and land cover (LULC) changes will cause environmental disturbances, particularly soil erosion. This research was aimed to estimate total amounts of soil loss using the Revised Universal Soil Loss Equation (RUSLE) model within a Geographic Information System (GIS) environment. LULC maps of Japan International Cooperation Agency (JICA) 2002 and Mekong River Commission (MRC) 2015 were used to evaluate the impact of LULC on soil erosion loss in Stung Sangkae catchment. LULC dynamics for the study periods in Stung Sangkae catchment showed that the catchment experienced a rapid conversion of forests to rice paddy fields and other croplands. The results indicated that the average soil loss from the catchment was 3.1 and 7.6 tons per hectare per year (t/ha/y) for the 2002 and 2015 periods, respectively. The estimated total soil loss in the 2002 and 2015 periods was 1.9 million tons per year (t/y) and 4.5 million t/y, respectively. The soil erosion was accelerated by steep slopes combined with the high velocity, and erosivity of stormwater runoff. The spatial distribution of soil loss showed that the highest value (14.3 to 62.9 t/ha/y) was recorded in the central, southwestern, and upland parts of the catchment. It is recommended that priority should be given to erosion of hot spot areas and appropriate soil and water conservation practices should be adopted to restore degraded lands.