基于抽样调查资料估算区域土壤侵蚀量

区域土壤侵蚀量估算是土壤侵蚀调查的重点和难点,为了利用抽样调查数据定量估算区域土壤侵蚀状况,以2011年第1次全国水利普查中的水力侵蚀抽样调查资料为基础,利用中国土壤流失方程(CSLE),通过地理信息系统估算2011年辽宁省的降雨侵蚀力、土壤可蚀性、地形、水土保持措施等侵蚀因子及侵蚀量,在此基础上对全省的水力侵蚀强度进行分级和面积统计,并与抽样调查结果进行对比.结果显示:全省各土壤侵蚀因子的估算结果与抽样调查结果较为接近;土壤水蚀以微度和轻度侵蚀为主,每年全省约85％的土地处于微度侵蚀(＜1000t/km2),而强度侵蚀(＞5 000 t/km2)面积仅占2％;抽样调查得到的独立工矿用地、果园、旱地和其他土地的侵蚀模数较估算得出的侵蚀模数大,而在草地、其他林地等土地利用类型上抽样调查得到的侵蚀模数却较估算得出的侵蚀模数小,主要原因可能是省域和抽样单元计算地形因子的DEM数据精度不同.总体上,该研究为如何利用抽样调查数据估算全国土壤侵蚀状况提供参考.

Estimation of regional soil erosion based on sampling survey

Background] The estimation of regional soil erosion is an important but difficult topic for soil erosion research.During the past years,artificial survey method had been used to make national soil erosion survey,classifying the soil erosion intensity in the topographic map according to vegetation coverage and slope gradient was time-consuming.The national soil erosion investigation based on remote sensing image and GIS technology in large scale had also be conducted,the soil erosion type and intensity were evaluated only according to vegetation coverage and slope,but without rainfall,soil erodibility and other important factors.Thus,how to present the regional spatial distribution of soil erosion quickly and accurately is an urgent issue.Methods] In order to study method of estimating the regional soil erosion by survey data,Liaoning Province was taken as the study area,soil erosion factors (rainfall erosivity,soil erodibility,topography,soil and water conservation measures) and soil erosion modulus in 2011 were estimated using Chinese Soil Loss Equation (CSLE) based on GIS technology and sampling data from the first nationwide water resources survey in 2011.The soil erosion intensity of the whole Liaoning Province were graded,and compared with the statistical results in sampling plots.Results] The results showed that the estimated soil erosion factors were relatively consistent with the sampling results apart from slope length and gradient.And the difference of scale accuracy of the topographic data mainly contributed to the difference of slope length and gradient between the whole Liaoning Province and sampling plots.The data from sampling plots and the whole province both showed the similar results that the intensity of soil erosion in Liaoning Province were mostly slight and light.Every year the intensity less than 1 000 t/km2 accounted for about 85％ of the area,while the one greater than 5 000 t/km2 accounted for only 2％ of the area.The soil erosion modulus of other land was the largest (1 777.65 t/km2),folllowed by the dryland (842.20 t/km2) and grassland (794.87 t/km2),the urban residence (11.69 t/km2),paddy field and water areas (17.14 t/km2) were the smallest.Compared to the estimated results of the whole province,the erosion modulus of sampling plots in the independent industrial and mining area,other garden and other land were larger with average values of 3 974.89 t/km2,1 656.95 t/km2 and 807.74 t/ km2 respectively,while the erosion modulus of sampling plots in grassland and other woodland were smaller with average values of 551.48 t/km2 and 197.55 t/km2 respectively,and these differences might resulted from the different resolutions of DEM data between the whole province and sampling plots Conclusions] The research suggests that it is highly credible to estimate regional soil erosion modulus relying on sampling survey data and soil erosion model.And it can provide a reference for the estimation of regional soil erosion using sampling survey data.