Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data...Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data and soil erosion data observed between 2003 and 2004 over 10 field plots with different slope length in Heshan Farm, Heilongjiang Province. We found that soil erosion rate over long slopes in the black soil region changed alternatively along the slope and creates alternative zones of intensive erosion and week erosion.The exact place of each zone is different for different rainfall conditions. In a year with less and mild precipitation, rill cannot happen within the top 50 m, while in a year with large and intensive precipitation, rill can be formed starting even at 15 m from the top of the slope.展开更多
Without taking inducing factors into consideration, this paper adopts a quantitative analysis of the bottom factors in the Three Gorges Reservoir area, studies the relationship between the bottom factors and the devel...Without taking inducing factors into consideration, this paper adopts a quantitative analysis of the bottom factors in the Three Gorges Reservoir area, studies the relationship between the bottom factors and the development of landslides, and then zones the area according to risk levels. The bottom factors adopted in this paper include lithological characters（U1 ）, gradient（U2 ）, slope form （U3）, difference of helght（U4 ）, and slope orientation（U5 ）. In 4 650 km^2 of the studied area, the areas of the very high, high, medium and low hazard degree area respectively were 57. 94 km^2 , 2 305.15 km^2, 1 241.6 km^2, 1 045.31 km^2. The methodological steps are （1） inversion statistic analysis, （2） the analysis of contribution ratio and weighing, （3） getting results via fuzzy evaluation of risk levels.展开更多
Soil type maps at the scale of 1︰1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China.However,the soil property maps pro...Soil type maps at the scale of 1︰1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China.However,the soil property maps produced through conventional direct linking method usually suffer low accuracy as well as the lack of spatial details within a soil type polygon.This paper presents an effective method to produce detailed soil property map based on representative samples which were extracted from each polygon on the 1︰1000 000 soil type map.The representative sample of each polygon is defined as the location that can represent the largest area within the polygon.The representativeness of a candidate sample is determined by calculating the soil-forming environment condition similarities between the sample and other locations.Once the representative sample of each polygon has been chosen,the property values of the existing typical samples are assigned to the corresponding representative samples with the same soil type.Finally,based on these representative samples,the detailed soil property map could be produced by using existing digital soil mapping methods.The case study in XuanCheng City,Anhui Province of China,demonstrated the proposed method could produce soil property map at a higher level of spatial details and accuracy:1)The soil organic matter(SOM)map produced based on the representative samples can not only depict the detailed spatial distribution of SOM within a soil type polygon but also largely reduce the abrupt change of soil property at the boundaries of two adjacent polygons.2)The Root Mean Squared Error(RMSE)of the SOM map based on the representative samples is1.61,and it is 1.37 for the SOM map produced by using conventional direct linking method.Therefore,the proposed method is an effective approach to produce spatial detailed soil property map with higher accuracy for environment simulation models.展开更多
基金National Basic Research Program of China, No.2007CB407207Knowledge Innovation Project of Institute of Geographic Sciences and Natural Resources Research,CAS,No.CXIOG-A04-10the support from CAS through its "One Hundred Talent" program
文摘Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data and soil erosion data observed between 2003 and 2004 over 10 field plots with different slope length in Heshan Farm, Heilongjiang Province. We found that soil erosion rate over long slopes in the black soil region changed alternatively along the slope and creates alternative zones of intensive erosion and week erosion.The exact place of each zone is different for different rainfall conditions. In a year with less and mild precipitation, rill cannot happen within the top 50 m, while in a year with large and intensive precipitation, rill can be formed starting even at 15 m from the top of the slope.
文摘Without taking inducing factors into consideration, this paper adopts a quantitative analysis of the bottom factors in the Three Gorges Reservoir area, studies the relationship between the bottom factors and the development of landslides, and then zones the area according to risk levels. The bottom factors adopted in this paper include lithological characters（U1 ）, gradient（U2 ）, slope form （U3）, difference of helght（U4 ）, and slope orientation（U5 ）. In 4 650 km^2 of the studied area, the areas of the very high, high, medium and low hazard degree area respectively were 57. 94 km^2 , 2 305.15 km^2, 1 241.6 km^2, 1 045.31 km^2. The methodological steps are （1） inversion statistic analysis, （2） the analysis of contribution ratio and weighing, （3） getting results via fuzzy evaluation of risk levels.
基金Under the auspices of Program of International Science & Technology Cooperation,Ministry of Science and Technology of China(No.2010DFB24140)National Natural Science Foundation of China(No.41023010,41001298)National High Technology Research and Development Program of China(No.2011AA120305)
文摘Soil type maps at the scale of 1︰1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China.However,the soil property maps produced through conventional direct linking method usually suffer low accuracy as well as the lack of spatial details within a soil type polygon.This paper presents an effective method to produce detailed soil property map based on representative samples which were extracted from each polygon on the 1︰1000 000 soil type map.The representative sample of each polygon is defined as the location that can represent the largest area within the polygon.The representativeness of a candidate sample is determined by calculating the soil-forming environment condition similarities between the sample and other locations.Once the representative sample of each polygon has been chosen,the property values of the existing typical samples are assigned to the corresponding representative samples with the same soil type.Finally,based on these representative samples,the detailed soil property map could be produced by using existing digital soil mapping methods.The case study in XuanCheng City,Anhui Province of China,demonstrated the proposed method could produce soil property map at a higher level of spatial details and accuracy:1)The soil organic matter(SOM)map produced based on the representative samples can not only depict the detailed spatial distribution of SOM within a soil type polygon but also largely reduce the abrupt change of soil property at the boundaries of two adjacent polygons.2)The Root Mean Squared Error(RMSE)of the SOM map based on the representative samples is1.61,and it is 1.37 for the SOM map produced by using conventional direct linking method.Therefore,the proposed method is an effective approach to produce spatial detailed soil property map with higher accuracy for environment simulation models.
