| Soil erosion is one of the most serious problems which currently affectingagricultural development and ecological stability, caused by the human irrationaluse of land. The serious consequences of agricultural caused cultivated land areadecreased and soil fertility degradation. China’s population is the first number ofthe world, due to soil erosion directly impact of social stability and sustainabledevelopment. So soil erosion problems must be solved urgently.Qinghai Loess Hilly region is located in the east of Qinghai Province, is atransition zone between the Loess Plateau and the Tibetan Plateau.The uniquegeographical location and natural conditions, combined with man-made severevandalism, made the region ravines, and also was the main source of sediment ofChinese Mother River-Yellow River, It is the most serious soil erosion andecological environment of the most vulnerable areas around the world.Theregion of soil erosion dynamic monitoring is without delay, to grasp the situationand its influencing factors of soil erosion timely, provide a basis for the work ofprevention, erosion control work is of strategic significance in water loss and soilerosion prevention and control work of nationwide.For soil erosion in Loess Hilly Region of Qinghai province monitoringworks from two aspects discussed, on the one hand is in situ monitoring, on theother hand is based on ArcGIS macro research. In situ monitoring based on theresults of field surveys to ditch system as a unit, select qualified20erosion gullyas monitoring objects, the monitoring year from2011to2013, analyzed therelationship between the thickness of soil erosion with the erosion factors,andcontrast between different monitoring data in the three years, to verify theeffectiveness of the measures of soil and water conservation. Macro research combined with "3S" technologies and based on1:50000electronic topographicmap for the data support, select Ledu Gangzigou and Huzhu Hongyazigou twobasins analysis.Using ArcGIS software of Surface Analysis tool to extractdifferent slope and aspect under the different mesh size of DEM, andcomparative Analysis to determine the optimal DEM grid size; by comparingdifferent threshold extraction of river network, then determine the optimalthreshold value.Using hydrology module to complete the extraction of networkand watershed division, then calculated the gully density, according to soilErosion of Classification standards (SL190-2007), determine the erosion of subwatershed, then ultimate combination of county boundary maps to completeerosion class of the township grading, to guide the township of soil and waterconservation work.Situ monitoring study results show that each single factor’s influence on thethickness of soil erosion is not very significant, but the relationship between thethickness of soil erosion and vegetation coverage significantly, the data of threeyears of monitoring show that Ledou, Huzhu and Huangyuan erosion gullysample data is higher than others, but the thickness of soil erosion showed adownward trend overall, the regional soil and water conservation measures to agood effect, the soil erosion have been effectively curbed.Trees Water holdingcapacity than shrubs, the gully’s upper part and the middle water holdingcapacity higher than the lower part. The macro research results show that themacroscopic level in a very intense soil erosion over occupied area is not large,but the main stream of soil erosion intensity is significantly higher than tributary,forest area of soil erosion is the weakest, in situ analysis, the relationshipbetween the thickness of soil erosion and vegetation coverage significantly, fullydescription of the vegetation has significant inhibitory effect on soil erosion.According to the erosion intensity level diagram can be observed the townshiperosion, the erosion of Hongyazigou watershed is better than that of Gangzigouwatershed. The macro research is the basis and support for future sample tosetting and water loss and soil erosion prevention and control work. |
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