Effects of Land Use and Slope Gradient on Soil Erosion in a Red Soil Hilly Watershed of Southern China

Abstract

Abstract:A study was undertaken to develop an appropriate plan of land use under suitable slope gradient to control soil erosion from a red soil hilly watershed of southern China by using the GeoWEPP (Geo-spatial Interface for the Water Erosion Prediction Project) model. The model was calibrated and validated using monitoring data of the outlet from 2010 to 2012, in which the 2010 and 2012 annual total runoff and sediment yield data were used for calibration, and the 2011 monthly runoff and sediment yield data for validation. The performance of the model in validation period were good with a high coefficient of determination values of 0.98 and 0.93 and Nash-Sutcliffe simulations of 0.96 and 0.91 while low root mean square error values of 6.91 mm and 0.35 t respectively for runoff and sediment yield. Subsequently, the model was used to simulate four typical land use (forest, farm, orchard, and fallow land) in the study area to evaluate their impacts on soil erosion production. The results showed that the runoff decreased by 44.7% and 61.1% for forest and orchard land compared to the current land use, as well as the sediment yield OPEN ACCESSSustainability 2015, 7 14310 decreased by 43.7% and 68.6%. While the runoff and sediment yield increased by 52.2% and 42.6% for farm land, and 48.8% and 29.6% for fallow land. As the same time, soil erosion increased with increasing of the slope gradient of the quadratic regression equation for all land use. The critical slope gradient of 15° for returning the farmland to forest or others is suitable in the red soil region but is not accurate. The result of the study provides good scientific evidence for developing an appropriate plan of land use in the watershed and other similar areas.

Upgrade of the surface erosion model with the channel erosion areas – the Bohinj municipality case-study

“…Obstajajo tudi seveda števil-ne druge enačbe za izračun stopnje erozije glede na naklon (npr. Chaplot & le Bissonnais, 2003;Assouline & Ben-Hur, 2006;Zhao et al, 2014;Zhang et al, 2015), ki pa upoštevajo še številne druge parametre, kot so intenziteta in trajanje padavin, usmerjenost brazd, natančen tip vegetacije in njena gostota, ki jih za dano območje ni bilo možno pridobiti ali izmeriti. Enačbe, ki določajo stopnjo erozije in ki so bile dobljene pri navedenih razikavah so posledično zelo specifične za testne lokacije, ki so jih raziskovalci uporabili za izračun sopnje erozije.…”

Coupling Universal Soil Loss Equation and GIS Techniques for Estimation of Soil Loss and Sediment Yield in Algash Basin

“…Only 0.0002796% and 0.0000042% were classified as severe and very severe potential risk respectively. Figure 11 below proves that the mean annual soil loss is proportional to the slope due to the effect of topographic factor as mentioned by Zhang et al (2015). When the slope is more than 140% the mean annual soil loss will reach the maximum mean annual soil loss (7.76 ton/ha.year), in contrast when the slope is very low (0-2%), the mean annual soil loss will be very low (0.08 ton/ha.year).…”

Subdividing Large Mountainous Watersheds into Smaller Hydrological Units to Predict Soil Loss and Sediment Yield Using the GeoWEPP Model

“…A similar outcome has been reported by Saghafian et al [11] as they concluded that converting natural land use into other uses, particularly dry-farming, played the dominant factor in increasing the amount of sediment load within the Kasilian Watershed in Iran. In another study, the results of a GeoWEPPapplied experiment on a hilly watershed in southern China indicated that land use type changing from forest to agriculture caused sediment amount to increase by 42.6% [32]. Morover, in a research investigating how soil loss and sediment yields were affected by the land-use/land-cover scenarios using a GeoWEPP model, Maalim et al [14] found that the average annual sediment yields increased from 0.13 t/ha to 2.15 t/ha for current agricultural lands and pre-settlement land-use/land-cover, respectively, within the Le Sueur Watershed in Minnesota.…”