| Mountainous small watershed is a natural catchments as well as a complex system out of the sub-system of ecology, economy and society. The comprehensive management using small watershed as unit is an effective approach to ameliorate the economical environment and accelerate agriculture and rural economy development. Evaluation of management effect in small watershed has been the studying hotspot, but study on land resources sustainable use in small watershed is still in primary period. Now, the Three Gorges Reservoir Area is faced with three serious problems, namely, the deterioration of ecological environment, the economic poverty and the resettlement of over one million people and irrational land use in small watershed is one of the main reasons for the serious soil erosion and economic poverty in TGRA. Taking Shiwanxi small watershed as a case, the author made an assessment on the land resources sustainable use and the results of this paper were expected to provide scientific references not only for the local government, but also for the TGRA in small watershed management and construction of ecological environment.The general consideration for this study was to summarize and conclude existing results and establish a theoretical foundation for proving study and policy undergoing. Detected by the theoretical system, a survey was made on land resources, natural, social and economic conditions in Shiwanxi small watershed. Based on this, the author selected some indexes with methods of Systems Analysis and Frequency Stat then assessed the land use from 1996 to 2002 with the Main Component Analysis Method. Finally, the paper provided strategic idea and practical countermeasures for land resources sustainable use and economy sustainable development according to the existing problems revealed by the assessment.1 An analysis of land use in Shiwanxi small watershedAnalyzing the land resources and land use with GIS, the author found the areas of land increased with the steep of slope and the rise of altitude. The slopes and elevation was separately divided into 3 grades according to the impact levels on the land use. Slope grades were: 0-15°, 15-25°, >25° and their proportions was 18.54%, 27.30% and 54.16% respectively. Elevation grades were: <500m a.s.1, 500-800m a.s.1, >800m a.s.1 and their proportions was 22.46%, 30.15% and 7.38% respectively. In the watershed, woodland, infield and garden plot respectively accounted for 43.17%, 23.39%, 13.31% and appeared obvious vertical differentiation, that was, woodland was mainly distributed on the slopes of >25° over 800m a.s.1 and garden plot was mainly distributed on the slope of 0-15° and 15-25° below 800m a.s. 1.How to use rationally the lands in mountainous small watershed is very important to preservesoi 1 quality and develop sustainable land use model. There was a study undertaken to evaluate the effect of land use on soil quantity. Thinking of soil organic matter, total N, total P, total K and soil granule composition, the soil degradation index was calculated and that of woodland, sparse woodland, crude grassland, garden plot of pear, garden plot of mandarin orange and slope dry land was separately -10.09%, -18.37%, -5.73%, -6.52% and -8.46% compared to woodland. The results indicated that deforestation and cultivation led to severe soil degradation.This article also analyzed the social and economic conditions. The input-output analysis showed that the agriculture structure did not correspond with land structure. In the constitution of all products, plantation occupied the most and it was the main income resources. At the same time, the forest and fruit were in low benefit with net income of 94.16yuan per 100yuan because the benefit was long-term.2 Sustainable assessment of land use in Shiwanxi small watershedBased on the land resources, land use, natural, social and economic conditions of Shiwanxi small watershed and the existing study results, 24 indicators were put forward with methods of Systems Analysis and Frequency Stat to... |
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