Nanan District, Chongqing Based On Gis In Soil Erosion Risk Assessment Study

Soil and Water Loss is the worldwide serious problem of enwironment and the main form of Eco-destory. Serious Soil and Water Loss has become the restrictive factor of the sustainable,stable and healthy development of a country's economy. Three Gorge Area form Chong-qing to San-dou-ping of Yi-chang was the most important region in the upper reaches of Chang-jiang river where the loss of water and soil was urgently needed to be harnessed. The situation of the loss of water and soil not only affected upper reaches of Chang-jiang, even the whole watershed of Chang-jiang. Geographical Information Syetem (GIS),as a jumped-up new technology, has the functions of data collecting, storing and managing, spatial analyzing,dynamic forecasting, decision-making and supporing.GIS has been widely applied and made great progress in many fields, such as resources management, urban programming, land evaluation, environment monitoring and the study on regional Soil and Water Loss. This paper focuses on the core problem of the research of the potential assessment on the danger of Soil erosion, the 3 aspects of the loss of water and soil were discussed based on the soil corrodes potential dangerous appraisal in district of south bank of Chongqing. The method and model of predicting and assessing the loss of water and soil was build. The assessment attempts to use the technology of GIS so as to solve such problems in past soil corrodes assessment as low efficiency, bad accuracy, and waste of time and strength and to make assessment of soil corrodes informed and scientific.1. The relevant theoretical foundations about the Soil erosionOn the basis of technology of geographical information system, the previous part of the article introduces the relevant concepts on assessment of soil corrodes: including soil erosion essential characteristic, main task, function and used technological method. Modem GIS technology used in assessment of soil erosion.2.Prediction of the loss of water and soil of Soil erosion in district of south bank of ChongqingThe method of supplying Geographical Information System ARC/INFO to predict soil erosion amount was probed in this paper. Based on the field survey, the geographical data base of the district of south bank of Chongqing was built and the method of calculating the value of factors of USLE was studied. By the support of ARC/INFO Geographical Information System and integration of GIS and USLE,the soilerosion amount of SouthBank was prediaed. Results showed that the annual average soil erosion amount was 2793 t/km2 ,strong erosion and extremely strong erosion was 52.82km2, accounts for 39. 37%, the farmland with abrupt slope and the forest and meadow with low coverage rate.3. the assessment on the danger of Soil erosion in district of south bank of ChongqingThe method of dividing assessed units on the danger of soil erosion was inquired and the danger of soil erosion appraised in Chongqing province and the service life that this soil top layer can be born calculated and corrode by means of the ratio of losing soil deduct critical effective soil layer thinkness with depth annually and System Cluster supportes by the software of ARC/INFO8.3.The factors affecting the danger of soil erosion were considered in an all-round way and the limitation and indistinction was avoided during the process of assessment. Results showed that : It is the high mound and low mound that the biggest potential hazard of Soil erosion.With the increase of the slope, the effective thickness of soil will be reduced , the speed of corroding will be strengthened and the Potential danger of Soil erosion is strengthened too.When the soil was disturbed by people, the Potential danger of Soil erosion is bigger. Hillside fields smaller than 25 "to develop should finish water and soil conservation measure, one that greater than 25 ° should forbid being cultivated.It is proved by practice that in comparison with the potential assessment on the danger of Soil erosion based on paper map, the GIS-based hazard assessment of Soil and Water Loss is faster and more effective. Coordinating with appropriate assessment model it can replace the traditional method of hazard assessment so as to improve the efficiency and the accuracy of hazard assessment of Soil and Water Loss. Then, the assessment on the danger of Soil erosion advances further in modelized, quantified and modernized direction.