Study Of The Desertification Situation Evaluation In Hedong Sandy Land Of Ningxia Hui Autonomous Region

The Hedong sandy land is located on the transitional zone between Arid and semi-arid regions, which belongs to the typical interlaced zone of agriculture and animal husbandry in China. The desertification in forms of wind erosion and soil sandification threatens the local economic development and eco-safety seriously over there. To understanding the desertification dynamics and serve the integrated and scientific combating of desertification, based on the method combining 3S techniques with ground survey, the process, driving factors, monitoring technique system, status and dynamics of desertification in the Hedong sand land were studied, and the major results are as follows:(1) The desertification Monitoring technique System. Based on the different desertification monitoring technique and method, desertification comprehensive monitoring technique system in Hedong sandy land was put forward and set up, which can be used for desertification monitoring and evaluation at different spatial scales.(2) The process and driving factors of desertification. According to the different time scale, the Desertification process of the sandy lands to the east of the yellow is divided into three processes: desertification process in geological history, desertification process in human being history and modern desertification process. The modern desertification process consists of farmland wind erosion process, grasslands degradation process, fixed dune activation and drifting sand moving process. The modern desertification process is land degradation process driving by the interaction of artificial factor and natural factor. The main driving factors for desertification are over-reclamation and overgrazing, irrational use of water resource etc. Population is the direct and major drive of desertification. Besides there still includes the factor of economic, technique, policy and the cultural, different drive have different drive mechanism.(3) Desertification evaluation based on ground survey. The desertification indicator system at community scale for desertification evaluation was set up, which consisted of vegetation coverage, content of soil organic matter and biomass. Evaluation results by fuzzy mathematics were accord with the field investigation. According to community evaluation result, the sandy area belongs to medium-strength degree desertification. Using the method of combining Expert consulting system and hierarchy analysis, the desertification assessment indicator system is set up on regional scale, which includes 2 first-class indicators, 6 second-class indicators and 15 third-class indicators. Through the fuzzy comprehensive evaluation, the desertification of the Hedong sandy land is of severe desertification on the region scale.(4) The desertification situation evaluation based on 3S technique. The remote sensing data express that the Hedong sandy lands is mainly medium-strength degree desertification. Compared with 1986, the desertification area decreased, desertification degree descended, and enter to a stage that the desertification control exceed destroy in 2003. During 1986-1995, the desertification development velocity is 16.25 km~2/a, the expanding rate is 0.34% annually, and in this stage, desertification area became larger, desertification degree is worse. During 1995-2003, the desertification development velocity is -51.85 km~2/a, and on this stage, desertification area decreased, desertification degree is better. Make a evaluation to desertification development trend of the Hedong sandy land using Markov process model, the result express that the desertification area the Hedong sandy land will decrease, desertification grading degree will reduce, there are more advantageous to combat desertification.