The Study Of The Process And Mechanism Of Soil And Water Loss In The Hilly Area Of Jiaixan County

The soil and water loss has been one of major environmental issues facing Tianjin City and even the whole China.With the increasing population and the rapid economic development,various natural resources have been exploited excessively,thus leading to the serious deterioration of ecological environment.For the hilly area of Jixian County with a large area and weak ecological environment,the irrational economic activities have resulted in the serious soil and water loss and even slowed down the economic development.At present,it has become the area suffering most from the soil and water loss in Tianjin and also a typical rocky mountainous area featured by soil and water loss in North China.Based on the existing monitoring sites and basic materials,this paper has chosen the hilly area of Jixian County as an object of research.The study of the process and mechanism of soil and water loss has consisted of five parts.The first part is the study of the occurrence and development of soil and water loss.By analyzing the rainfall characteristics of different areas as well as the runoff and sediment yield in the typical areas,this paper has researched the potential ability of different rainfall to cause the soil erosion.Different water erosion prediction models have been also built.Moreover,the occurrence and development of soil and water loss during different time sequences and in different spatial areas have been also discussed.The second part is the study of the formation mechanism of soil and water loss.By collecting the observation materials available,analyzing the terrain conditions such as the slope degree,slope length and slope shape,studying the measures to conserve the water and soil,different modes of land utilization as well as the volume of runoff and sediment flowing in those runoff areas and stations with different rainfall in terms of intensity,amount and category,this paper has made a study of the development law and formation mechanism of soil and water loss.The third part is the study of different measures to conserve the water and soil.Based on the experiment data of typical areas,it has calculated the capacity to conserve the water and soil through different measures.The materials regarding the slope management has been surveyed and collected.The benefit of the project aimed to conserve the water and soil has been also calculated.The materials regarding the forest and grassland management have been surveyed and collected to calculate the benefit ofconserving the water and soil.The materials concerning the ditch management in the hilly area has been surveyed and collected to calculate the benefit of conserving the water and soil.The fourth part is the study of the economic loss caused by soil erosion.The materials regarding the physical loss in the form of runoff erosion,sediment retention,deposition,water conservancy facilities,village and farming land as a result of soil erosion has been surveyed and collected.The economic loss caused by the soil erosion has been also determined.The materials regarding soil survey and observation have been collected.The content of soil nutrient has been surveyed and determined.The loss of the nutrients such as the organic mater,N,P and K caused by the soil erosion has been also determined.The economic loss will be determined on the basis of the comparable price of the standard fertilizer containing the same amount of soil nutrients.The fifth part is the study of the economic benefits of the comprehensive measures taken to conserve the water and soil.Based on the first water resource survey and historical materials,the main area with the measures taken to conserve the water and soil will be determined.Judging from the observation result of runoff area and the proportion of different measures,the benefit of the measures taken to conserve the water and soil will be estimated.The direct economic benefit of the measures taken to conserve the water and soil will be calculated based on the economic benefit of different measures.