Evaluation of soil erosion vulnerability in Hubei Province of China using RUSLE model and combination weighting method

Soil erosion has been recognized as a critical environmental issue worldwide.While previous studies have primarily focused on watershed-scale soil erosion vulnerability from a natural factor perspective,there is a notable gap in understanding the intricate interplay between natural and socio-economic factors,especially in the context of spatial heterogeneity and nonlinear impacts of human-land interactions.To address this,our study evaluates the soil erosion vulnerability at a provincial scale,taking Hubei Province as a case study to explore the combined effects of natural and socio-economic factors.We developed an evaluation index system based on 15 indicators of soil erosion vulnerability:exposure,sensitivity,and adaptability.In addition,the combination weighting method was applied to determine index weights,and the spatial interaction was analyzed using spatial autocorrelation,geographical temporally weighted regression and geographical detector.The results showed an overall decreasing soil erosion intensity in Hubei Province during 2000 and 2020.The soil erosion vulnerability increased before 2000 and then.The areas with high soil erosion vulnerability were mainly confined in the central and southern regions of Hubei Province(Xiantao,Tianmen,Qianjiang and Ezhou)with obvious spatial aggregation that intensified over time.Natural factors(habitat quality index)had negative impacts on soil erosion vulnerability,whereas socio-economic factors(population density)showed substantial spatial variability in their influences.There was a positive correlation between soil erosion vulnerability and erosion intensity,with the correlation coefficients ranging from-0.41 and 0.93.The increase of slope was found to enhance the positive correlation between soil erosion vulnerability and intensity.

Recent advances in assessment of soil erosion vulnerability in a watershed

Soil erosion is one of the most critical hazards adversely affecting both environment and economy.Assessment of the annual soil erosion rate provides information on soil erosion risk zones indicating the areas with high,severe and low risks.Modelling and prediction of soil erosion has a long history of more than seven decades.It becomes imperative to be familiar with the quantum of studies conducted and methods employed across the world to assess vulnerability of ecosystems to soil erosion to plan strategies for their conservation.There are several methods based on various factors like land use,soil quality,topography etc.available to assess the susceptibility of a region to soil loss.With time the gap in understanding of such models and their use around the world has increased.Numerous models for assessing soil erosion exist but there is a lack of knowledge on spatial distribution of the methods being used.Academic papers related to assessment of soil erosion vulnerability published during the past three decades(1991—2019)were reviewed.Total 160 studies were reviewed to understand advances in the methods used to assess soil erosion vulnerability worldwide,identification of the most popular methods and proportion of studies conducted in the fragile region of Himalayas.The results show that 18 different methods have mainly been used to assess soil erosion risk in different regions.These methods include statistical,physical,process based and empirical models.The use of few physical methods like ANSWERS and SHE has decreased with time while that of physical and process methods like RUSLE,SWAT,WEPP and PESERA has increased with time.The review highlighted that various models being used worldwide are based on their suitability to the region.It also brings to attention that few models like PESERA,EUROSEM and WEPP are mostly being used concentrated in a particular region.Models like PESERA and EPM are mostly used in European region and may be encouraged to estimate soil erosion in Himalayan region.The review also highlights lack of studies with inclusion of water quality as an important parameter while assessing soil erosion vulnerability in the region.The review suggests that in case of lack of data,various statistical methods like PCA,CF,FUZZY etc can be preferred for qualitative assessment over quantitative assessment Considering availability of accurate input,researchers need to attempt more methods and perform comparative studies to attain accurate results for assessing soil erosion vulnerability leading to strategizing soil conservation in fragile regions.

Soil loss tolerance in the black soil region of Northeast China

Soil loss tolerance （/） is the maximum rate of annual soil erosion that is tolerated and still allows a high level of crop productivity to be sustained economically and indefinitely. In the black soil region of Northeast China, an empirically determined, default Tvalue of 200 （t/km2.a） is used for designing land restoration strategies for different types of soils. The ob- jective of this study was to provide a methodology to calculate a quantitative T for different black soil species. A field investigation was conducted to determine the typical soil profiles of 21 black soil species in the study area and a quantitative methodology based on a modified soil productivity index model was established to calculate the Tvalues. These values, which varied from 68 t/km2.a to 358 t/km2-a, yielded an average Tvalue of 141 t/km2.a for the 21 soil species. This is 29.5% lower than the current national standard T value. Two significant factors that influenced the T value were soil thickness and vulnerability to erosion. An acceptable reduction rate of soil productivity over a planned time period of 1% is recommended as necessary for maintaining long-term sustainable soil productivity. Compared with the cur- rently used of regional unified standard T value, the proposed method, which determines T using specific soil profile indices, has more practical implications for effective, sustainable management of soil and water conservation.