| Soil erosion is the major environmental problem human face in the process of developments,which has threatened the survival of the human race and attracted more and more attentions fromthe government, scientists and technologists in global world. Study on the soil erosion is closelyrelated to human survival and development, which has become the international issue soilscience, agricultural science and environmental science concern in the 21th century. It is of greatsignificance to carry out research on the soil erosion.Yihe River in Shandong province Zibo city Yiyuan County is the second great river. YiyuanCounty is located in the Yi River upstream regions, which is the key soil erosion control countythe ministry of water resources identified. The study is based on Chinese soil loss equationestablished by Liu Baoyuan The paper takes SPOT 10m resolution multispectral image and 2.5mresolution panchromatic images in the April of 2009 as the remote sensing data, ASTER GDEM30m resolution DEM data as terrain data sources and 1:500000 soil map in the Shandongprovince as soil data sources, combining the other survey data. It deals with all basic datathrough geometric correction and projection transformation operation, and then converts the datato the same reference to facilitate data overlay analysis.This study uses grid sampling survey method the Ministry of water resources promoted toconvert the study area of Yiyuan County in 4 levels. The third level is 5km×5km grid and thefourth level divides in 5×5 on the basis of the third level. Basic sampling unit is located on thecenter grid in the third level. Based on the field investigation in the basic sampling unit, thepaper makes use of 1m×1m quadrat to obtain the plot coordinates, vegetation coverage,vegetation types, tillage, soil and water conservation measures and other data. In order toestablish the interpretation signs, it is necessary to compare the remote sensing image with thefield survey data in the indoor room. It analysts quantitatively the rainfall erosion force, soilerodibility, slope length, slope, vegetation coverage, engineering measures, cultivation measuresand many other aspects that affect soil erosion to find the law. And then calculate the modulus ofsoil erosion in Yiyuan County. Finally, through comparing the grid sampling method results withthe results obtained from the traditional calculation method, it makes an analysis the overalldistribution of soil erosion law and puts forward the corresponding suggestions of soil and waterconservation management.From the studies, we know that the average soil erosion modulus is 2361t/km~2·a and the lossamount of the year is up to 3.4642 million ton. The mild and even worse erosion area is about1015.45 km~2, accounting for 69.2% of the total area of the study area. Moderate erosion area isabout 230.58 km~2, accounting for 15.71% and it has large distribution area and proportion. Strong soil erosion area is 89.81 km~2, accounting for 6.12%. Extreme intense erosion area is61.57 km~2, accounting for 4.20%. Severe erosion area is about 31.15 km~2, accounting for 2.12%and it has the smallest area and proportion. Moderate and above soil erosion areas are mainly inthe hills of an altitude of 200-800m and many low mountain regions, which are relatively highaltitude. The area full of low and high is the main district of soil erosion. Vegetation in the regionis main types of artificial vegetation, which are mostly crops and affected by human factorheavily. So the soil erosion is serious.Comparing grid sampling results with the traditional calculation results, it is shown that thesoil erosion modulus obtained from grid sampling investigation method is 2330 t/km~2·a. Theaverage soil erosion modulus acquired through the traditional calculation method is 2361 t/km~2·a.The difference between the two methods is 31 t/ km~2·a. This can monitor the study area throughgrid sampling method instead of traditional calculation method, which can save manpower,material and financial resources and can receive good results.By comparing the three different grid sampling methods, we can see that average modulusof soil erosion obtained from the regular grid sampling method is the most close to the calculatedresults of the overall study area, which is about 2330 t/km~2·a. But the average soil erosionmodulus in the inspected sampling unit is about 1822 t/km~2·a and the average soil erosion in theintegrated sampling unit is 2018 t/km~2·a. Therefore the calculated results in the use of regularsampling unit than the other sampling unit are closer to the true value. |
