Study On Ecological Security Evaluation Of Small Watersheds Based On Soil And Water Conservation In Mountainous Area Of Beijing

Soil erosion is one of the most serious ecological problems in our country, mountainous area of Beijing accounts for 62% of the total, which has complex geologic and topographic conditions. Soil erosion and serious geological disasters such as collapse, landslides and debris flows happen frequently. Soil erosion, as a type of ecological risk, directly affects the mountainous watersheds’ ecological security situation. This article combines soil erosion and ecological security evaluation, builds an ecological security evaluation system of mountainous watersheds in Beijing, and puts forward the methods and steps of the evaluation. A model called "PD weighted composite evaluation model"for ecological security of soil and water conservation in mountainous area of Beijing were built and applied to the evaluation. The results show that:Mountainous area of Beijing contains 576 small watersheds, five grades contain safety, less safety, normal, less dangerous, dangerous, respectively 16.7%,22.0%,24.8%,22.6% and 13.9%. Dangerous grade distributes in the west of Fangshan, east of Mentougou, east of Miyun and east of Pinggu; less dangerous grade surrounds Dangerous areas; Normal grade is widely distributed in various districts, especially in Yanqing, Huairou, and most of Miyun; Safety and less safety grade is mainly distributed in the west of mountainous area and north of Huairou. According to the analysis of soil erosion and geological disaster, three ways were used to verify the results, the results are in conformed with the actual situation, so the model has a high reliability.Finally the evaluation system was designed, The system’s design process, basic function modules and business function modules were introduced.The system can acquire indicators, grade indicators, calculate index, classify and query risk grade, including a complete set of evaluation process.