Assessment of soil erosion and sediment yield in Liao watershed, Jiangxi Province, China, Using USLE, GIS, and RS

Abstract

Soil erosion by water is a serious problem all over the world. In China, about 1 790 000 km 2 of land suffers from water erosion, which accounts for 18.3% of China's total area. This study was conducted in the Liao (潦) watershed in Jiangxi (江西) Province to assess annual soil erosion and sediment yield using the Universal Soil Loss Equation (USLE). A geographic information system (GIS) was used to generate maps of the USLE factors, which include rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover (C), and conservation practice (P) factors. By integrating these factors in a GIS, a spatial distribution of soil erosion over the Liao watershed was obtained. The soil erosion was found to vary from nil for flat and well-covered areas to more than 500 t/ha/a in mountainous places with sparse vegetation. The average soil erosion is 18.2 t/ha/a with a standard deviation of 109.3 t/ha/a. The spatial distribution of erosion classes was estimated. About 39.5% of the watershed is under the tolerant erosion rate, and 60.5% of the study area experienced erosion to different extents. A spatially distributed sediment delivery ratio(SDR) module was developed to account for soil erosion and deposition. It was found that the SDR value at the outlet of the Liao watershed was 0.206, and the sediment yield was 1.32 million t/a, which was 20% higher than the measured sediment. The results can be used to identify the soil erosion hot spots and develop the best soil erosion management practices and help estimate the quantity of soil that was transported into the downstream Poyang (鄱阳) Lake.

Erosion Potential Estimation by Network Measurement of Soil Properties in Coastal Areas after Clearcutting

“…The annual eroded soil depth, which was obtained from dividing the predicted soil erosion rate by the bulk density, ranged 2600-3200 --2 5 C o ff e e 9 -3 0 0 Hoyos [28] from 0.30 cm to 2.43 cm yr −1 , which is considered very severe soil loss according to the Natural Resources Conservation Service (NRCS) classifications of soil loss tolerance [42]. The relatively high soil erosion rates (from 21 to 249 tons ha −1 yr −1 ) during the period between the clearcutting of the white leadtrees and the establishment of next stands of reforested native trees (i.e., from May to July, 2008) were similar to the results obtained in other tropical forest catchments ( Table 2), indicating that soil erosion is a relatively severe problem worldwide [24,43].…”

Distribuição espacial da erosão potencial e atual do solo na Bacia Hidrográfica do Rio Sapucaí, MG

“…Por outro lado, a USLE tem sido extensivamente utilizada em diferentes escalas, principalmente pela simplicidade de sua formulação (Hui et al, 2010;Beskow et al, 2009;Wang et al, 2009;Pan;ZHANG;ZHAO, 2005), contudo, ainda apresenta limitações, e nesse sentido a RUSLE apresenta-se como uma ferramenta útil para esse tipo de avaliação. Sua avaliação resulta de diversos fatores que influenciam o processo erosivo, os quais são: erosividade da chuva (R), erodibilidade do solo (K), uso e manejo do solo (C), práticas conservacionistas (P) e topografia (LS), esse último representado pelos efeitos do comprimento de rampa (L) e da declividade (S).…”

“…Assim, as ferramentas associadas a um sistema de informações geográficas (SIG) podem facilitar especialmente a obtenção dos fatores topográficos através da derivação de um modelo digital de elevação (MDE), como mostram Wang et al (2009) A USLE originalmente foi desenvolvida para estimar a taxa média anual de perda de solo e aplicada em nível de parcelas de perda de solo padrão (Wischmeier & Smith, 1978). Com o advento dos SIG, também tem sido aplicada em nível de bacia hidrográfica, buscando-se desenvolver mapas com a identificação de áreas mais susceptíveis à erosão hídrica, e os resultados obtidos indicam sua capacidade de modelar áreas complexas, consistindo uma ferramenta bastante útil ao planejamento em escala de bacia hidrográ-fica (Hui et al, 2010;Beskow et al, 2009;Lufafa et al, 2003, Mati et al, 2000. Sua expressão consiste de uma combinação linear dos fatores que caracterizam a erosão (Wischmeier & Smith, 1978), conforme a Equação 1:…”

Water erosion vulnerability and sediment delivery rate in upper Iguaçu river basin – Paraná

“…On the other hand, RUSLE has been extensively used on different scales, principally for the simplicity of its formulation (HUI et al, 2010;WANG et al, 2009). Its evaluation results from many factors that influence the erosive process, which are: rainfall erosivity (R); soil erodibility (K); usage and management of the soil (C); conservational practices (P) and topography (LS), the lastmentioned represented by slope length effects (L) and declivity (S).…”