| China is one of the country that soil erosion problem came to more and more seriously. The semiarid region of western Heilongjiang province is an important grain production base in China . But for successive years of damage being caused by complicated and variable natural conditions, uneven distribution of precipitation in time and space, as well as environment changes led by long-term human intervention . The lead black soil were seriously eroded and soil erosion ecological getting worse . meanwhile , environment came to be deteriorated gradually .This dissertation is based on the field experiment made in Gannan Country, Heilongjiang Province. It studied this land the process of sediment running off and aggressive rainfall under diverse conservation measures of soil and water through artificial rainfall simulation test and natural rainfall test. The main conclusions are as follows:1. These tests indicated that black soil and water conservation measures had storage soil conservation effect , the way of districting to field ridges was better to the way of covering stalk .2. The analysis of process of different rainfall intensities and sediment of runoff plots was mainly about: Under each cultivation measures the runoff start-stop was at different times., the process lines was also different . the returning water process line also differred from another: Light rain intensity runoff durated late , Heavy rain intensity runoff durated early . Light rain intensity's process lines was slowing , Heavy rain intensity's process line was steeping . The greater the rainfall intensity was ,the larger strength of runoff yield and the total process of water line was , the steeper the returning water process lines were. Applying -uncovered slope and cross-sectional slope with ridges ,their production and soil erosion were severe than other cultivation measures. It was visible that the surface soil coverage can effectively reduce soil erosion. The covered stalk increased the surface roughness, reducing the scour of flowing water to surface , improving storage of soil water, increasing the ability of moisture-retaining , reducing soil erosion. The district field is better than other communities. is most difficultly produced soil erosion, is the best of soil and water conservation measures. In the trials of natural rainfall and rainfall process, analyzes shows a similar conclusion. 3. Rainfall erosivity every month ,the value of R is consistented with rainfall season changing trends. The rainfall erosivity and distribution of experimental plot showed single-peak, the highest value appeared in July, 35.06 J/m2, most focusing on June and July,it occupied 68.6% in total rainfall erosivity data.4. Using of the recorded rainfall data, artificial simulated rainfall data and runoff plots materials. Both according to previous research achievements, this dissertation determined the indicator of the rainfall erosivity factor R is E60I30 ,compared the advantage on simplized algorithm of three models R , include the CREAMS , RICHARDSON and a model that its structure was simple with others and needing information was available. The results showed that the stability of RICHARDSON model was the best. |
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