| Article11of the loess plateau by the typical small watershed dam system demonstration project for five consecutive years of field investigation method and the paper summarizes the experimental data and research, geared to the needs of the space unit of small watershed, build on the loess plateau watershed dam system of soil and water conservation monitoring system. At the same time, select the fork watershed soil erosion quantitative evaluation based on GIS and RUSLE research and analysis. Eventually set up for regional scale or larger geographical scale, with the monitoring method of soil and water conservation of small watershed as an object unit. Main conclusions are as follows:1、11small watershed in loess hilly gully dam system engineering of soil and water conservation monitoring method mainly USES the field and the fixed location monitoring of the planar investigation, soil erosion forecasting model combined with "3s" technology in the theory and method.Wild and planar investigation mainly includes:the fixed location monitoring of the slope treatment dynamics, dynamic channel construction field investigation statistics; To block sand with the buried concrete pile, artificial excavation deposition profile and homemade sedimentation method such as tablet fixed-point investigation; Sediment discharge by setting the transfer station, take advantage of the watershed exit on and discharge building fixed-point investigation; Investigating the embedding of draft survey method is used for the storage capacity; Measuring weir of the installation of the water use (trough), the channel section, can also according to the irrigation frequency and irrigation area and years irrigation quota calculation method for investigation; For closing and utilization method of field survey statistics monitoring; To increase production efficiency by the field survey, the layout of typical field monitoring method; Of dam system safety through on-the-spot exploration engineering surveying, monitoring survey statistics to verify the method.Soil erosion forecasting model combined with "3s" technology method mainly includes:the slope dynamic, dynamic channel construction and management of closing utilization monitoring using remote sensing image interpretation method; To block sand volume by adopting the combination of GPS and GIS method for dynamic monitoring. 2、article11of the loess plateau by the typical small watershed dam system demonstration project for five consecutive years of field investigation and data collection, analysis of small watershed water and soil conservation monitoring data evaluation the following conclusions:(1) the rainfall monitoring:Article11the watershed flood years of average rainfall of360.43mm, rainfall mainly concentrated in flood season from may to October, rainfall and flood season in July and August or September,73.42%of the flood season rainfall, rain days interannual difference is not big, average rainfall days5years during flood season is37.19d, more than10mm average rainfall days accounted for28.86%of the flood season rainfall days, in the basin rainfall is less than10mm of rainfall mainly light rain, at71.14%.planar erosion monitoring:this paper takes the fork of the small watershed based on GIS and RUSLE soil erosion quantitative evaluation and analysis, the model output with field survey data of the fit is very high, shows that this method is effective and feasible, and then come to the conclusion as follows:more than15°slope belt are higher than the average erosion watershed average erosion intensity, erosion accounted for87.66%of total erosion basin; Slope with half sunny slope erosion accounted for56.20%of total erosion basin, and its area is only50.16%of the total area of the basin; Vegetation coverage under20%or86.32%of the total watershed erosion of erosion, and the area is only34.62%of the total area of the basin; Degree of soil erosion, in order to bare land> other land residents farmland> grassland> terrace> garden land> forest land.(3)Dam siltation monitoring:By the end of2011, the11Typical Small Watersheds Project of Loess Plateau have built729dams, with a total storage capacity of131,263,100m3, controling a area of869.03km2, accumulating sediment14,040,200t. Among them, the backbone of the dam accumulated sediment volume9,476,700t, accounted for the entire dam sediment volume67.50%; medium-sized dams to2,900,400t, accounted for the entire dam sediment volume20.66%; small dam was1,662,900t, only to the entire amount of11.84%sediment dam and the rate of dam sediment averaged78.27%. The weight was only514,900t at sediment station, suggesting the construction of dam impounding the majority of sediment, some of the basic channel did not ditch sediment, making the event of flooding sediment increasingly coerced smaller, making the watershed sediment yield smaller and smaller. Most of the sediment dam was impounded,laying a foundation for the increaseing of basin as a high-quality farmland area.(4)Reservoir water monitoring:Storage capacity and watering rate have increased year by year. At the end of2011, the storage capacity and watering rate of the Dam system increased by49.2%and3.57%respectively than2007showing that the construction of dam system has played a significant role in terms of the storage capacity. The dammed-up water were used for agricultural irrigation and livestock use, further improving the local agriculture and animal husbandry production.(5)Closing and use of monitoring and increase efficiency:at the end of2011,11small watershed dam system accumulated silt ground covers an area of538.71hm2, closing and covers an area of1745.26hm2, closing and use area of1346.75hm2. Closing and yield the highest, followed by the terrace, slope is smallest. In2011, for example, closing and yield was63.79%higher than average yield per unit of small watershed, more than62.96%higher than that of terraced fields,166.68%higher than a slope, you can see closing and average yield is about2.7times that of the slope. Visible, small watershed dam system construction on the local agricultural production has played a very important role.Through the analysis and evaluation to the small watershed soil erosion quantitative,showing using soil erosion model with the combination of3s technology monitoring method is feasible, this paper puts forward that the method system of small watershed on the loess plateau soil and water conservation monitoring is based on the fixed-point monitoring and planar investigation, by means of soil erosion model, the trinity of "3s" technology as a platform of monitoring system. Through the analysis of the five years of monitoring data, the effect of small watershed water and soil conservation monitoring reached the expected aim. Through the study of this paper, for the loess plateau watershed dam system construction of soil and water conservation monitoring is provided for the further development of scientific and systematic methods and theoretical basis. |
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