scholarly journals Evaluating the spatial heterogeneity of soil loss tolerance and its effects on erosion risk in the carbonate areas of South China

2016 ◽  
Author(s):  
Yue Li ◽  
Xiaoyong Bai ◽  
Shijie Wang ◽  
Luoyi Qin ◽  
Yichao Tian ◽  
...  

Abstract. Soil loss tolerance (T value) is the ultimate criterion to determine the necessity of erosion control measures and ecological restoration strategy. However, the validity of this criterion in subtropical karst regions is strongly disputed. In this study, T value is computed based on soil formation rate by using a digital distribution map of carbonate rock assemblage types. Results indicated spatial heterogeneity and diversity in such values; moreover, a minimum of three criteria should be considered instead of only one criterion when investigating the carbonate areas of South China given that the “one region, one T value” concept may not apply to this region. T value is proportionate to the amount of argillaceous material in formations that determine surface soil thickness in homogenous carbonate rock areas; such values are 20 and 50 t/(km2 · a) in carbonate rock intercalated with clastic rock areas and 100 t/(km2 · a) in carbonate/clastic rock alternation areas. These three areas are each extremely, severely, and moderately sensitive to soil erosion. This erosion is extreme in karst rocky desertification (KRD) land and reflects the degree of erosion risk. Thus, the relationship between T value and erosion risk is determined with KRD as a parameter. The existence of KRD land is unrelated to T value, although this parameter indicates erosion sensitivity. In fact, erosion risk is strongly dependent on the relationship between real soil loss (RL) and T value rather than on either erosion intensity or the T value itself. If RL >> T, then erosion risk is high despite a low RL. Conversely, if T >> RL, the soil is safe although RL is high. Overall, these findings may clarify T value heterogeneity and its effect on erosion risk in a karst eco-environment; hence, innovative technological assessment solutions need not be invented.

Solid Earth ◽  
2017 ◽  
Vol 8 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Yue Li ◽  
Xiao Yong Bai ◽  
Shi Jie Wang ◽  
Luo Yi Qin ◽  
Yi Chao Tian ◽  
...  

Abstract. Soil loss tolerance (T value) is one of the criteria in determining the necessity of erosion control measures and ecological restoration strategy. However, the validity of this criterion in subtropical karst regions is strongly disputed. In this study, T value is calculated based on soil formation rate by using a digital distribution map of carbonate rock assemblage types. Results indicated a spatial heterogeneity and diversity in soil loss tolerance. Instead of only one criterion, a minimum of three criteria should be considered when investigating the carbonate areas of southern China because the one region, one T value concept may not be applicable to this region. T value is proportionate to the amount of argillaceous material, which determines the surface soil thickness of the formations in homogenous carbonate rock areas. Homogenous carbonate rock, carbonate rock intercalated with clastic rock areas and carbonate/clastic rock alternation areas have T values of 20, 50 and 100 t/(km2 a), and they are extremely, severely and moderately sensitive to soil erosion. Karst rocky desertification (KRD) is defined as extreme soil erosion and reflects the risks of erosion. Thus, the relationship between T value and erosion risk is determined using KRD as a parameter. The existence of KRD land is unrelated to the T value, although this parameter indicates erosion sensitivity. Erosion risk is strongly dependent on the relationship between real soil loss (RL) and T value rather than on either erosion intensity or the T value itself. If RL > > T, then the erosion risk is high despite of a low RL. Conversely, if T > > RL, then the soil is safe although RL is high. Overall, these findings may clarify the heterogeneity of T value and its effect on erosion risk in a karst environment.


2016 ◽  
Vol 47 (3) ◽  
pp. 127-133 ◽  
Author(s):  
Costanza Di Stefano ◽  
Vito Ferro

Soil loss tolerance is a criterion for establishing if a soil is potentially subjected to erosion risk, productivity loss and if a river presents downstream over-sedimentation or other off-site effects are present at basin scale. At first this paper reviews the concept of tolerable soil loss and summarises the available definitions and the knowledge on the recommended values and evaluating criteria. Then a threshold soil loss value, at the annual temporal scale, established for limiting riling was used for defining the classical soil loss tolerance. Finally, some research needs on tolerable soil loss are listed.


Author(s):  
Yue Cao ◽  
Shijie Wang ◽  
Xiaoyong Bai ◽  
Huiwen Li ◽  
Cheng Zeng ◽  
...  

Abstract. The prediction of soil erosion is critical to regional ecological assessment and sustainable development. However, due to the geological background of the karst area, the soil holding capacity is very limited, so it is necessary to consider the allowable loss of soil. Here we took thermodynamic dissolution model of carbonate rocks and the lithological characteristics to estimate soil loss tolerance, and corrected and quantitatively evaluated the soil erosion. Major findings are as follows: (1) The soil loss tolerance of homogenous carbonate rocks is 31.10 t · ha · yr−1, carbonate rock intercalated with clastic rocks is 120.81 t · ha · yr−1, carbonate/clastic rock alternations is 282.55 t · h · yr−1, and clastic rock is 500 t · ha · yr−1. (2) After the correction of the soil loss tolerance, the average annual amount of soil loss in the study area is 3.08 t · ha · yr−1, which is 41.12 % of the model. The predicted value of soil erosion is nearly the same as the observed value after modification. (3) It is necessary to reconsider the risk assessment model of soil erosion applicable to karst areas. This paper proposes an idea to estimate soil erosion based on the allowable loss of soil, which is more scientifically and accurately to reflect the soil erosion status of the study area compared with the traditional way. This study provides a corresponding reference for the formulation of soil and water conservation policies in China and the world's karst regions.


2013 ◽  
Vol 37 (5) ◽  
pp. 427-434 ◽  
Author(s):  
Junior Cesar Avanzi ◽  
Marx Leandro Naves Silva ◽  
Nilton Curi ◽  
Lloyd Darrell Norton ◽  
Samuel Beskow ◽  
...  

The process of water erosion occurs in watersheds throughout the world and it is strongly affected by anthropogenic influences. Thus, the knowledge of these processes is extremely necessary for planning of conservation efforts. This study was performed in an experimental forested watershed in order to predict the average potential annual soil loss by water erosion using the Universal Soil Loss Equation (USLE) and a Geographic Information System (GIS), and then compared with soil loss tolerance. All the USLE factors were generated in a distributed approach employing a GIS tool. The layers were multiplied in the GIS framework in order to predict soil erosion rates. Results showed that the average soil loss was 6.2 Mg ha-1 yr-1. Relative to soil loss tolerance, 83% of the area had an erosion rate lesser than the tolerable value. According to soil loss classes, 49% of the watershed had erosion less than 2.5 Mg ha-1 yr-1. However, about 8.7% of the watershed had erosion rates greater than 15 Mg ha-1 yr-1, being mainly related to Plinthosol soil class and roads, thus requiring special attention for the improvement of sustainable management practices for such areas. Eucalyptus cultivation was found to have soil loss greater than Atlantic Forest. Thus, an effort should be made to bring the erosion rates closer to the native forest. Implementation of the USLE model in a GIS framework was found to be a simple and useful tool for predicting the spatial variation of soil erosion risk and identifying critical areas for conservation efforts.


2020 ◽  
Vol 13 (1) ◽  
pp. 51
Author(s):  
Alexandra Pagáč Mokrá ◽  
Jakub Pagáč ◽  
Zlatica Muchová ◽  
František Petrovič

Water erosion is a phenomenon that significantly damages agricultural land. The current land fragmentation in Slovakia and the complete ambiguity of who owns it leads to a lack of responsibility to care for the land in its current condition, which could affect its sustainability in the future. The reason so much soil has eroded is obvious when looking at current land management, with large fields, a lack of windbreaks between them, and no barriers to prevent soil runoff. Land consolidation might be the solution. This paper seeks to evaluate redistributed land and, based on modeling by the Universal Soil Loss Equation (USLE) method, to assess the degree of soil erosion risk. Ownership data provided information on how many owners and what amount of area to consider, while taking into account new conditions regarding water erosion. The results indicate that 2488 plots of 1607 owners which represent 12% of the model area are still endangered by water erosion, even after the completion of the land consolidation project. The results also presented a way of evaluating the territory and aims to trigger a discussion regarding an unambiguous definition of responsibility in the relationship between owner and user.


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