| Longde County in Ningxia is a part of undeveloped regions in science and technology, and in the past, often carried out the control for the loss of soil and water aimlessly. So it is crucial to assess the current level of comprehensive small watershed management. To resolve above problems, this paper, taking Litaiping Watershed as an example and determining the well development of system structure and function as the key point of ecological effects, by comparing the trend of changes in the characteristic value of eco-system structure, energy flow and material flow before and after watershed management, reveals the orientation of its ecological environmental development; and also by using economic analysis, analyzes the benefit of investment. And the integrated effect of comprehensive small watershed management was studied in the way of ecology and economy. The main results showed:1. Changes in system structure: 1) Land-use structure: After controlling the loss of soil and water for 4 years and agricultural management for 9 years, the ratio of farmland, forest and pasture land is changed from 6.2:2.0:1.0 into 1.9:1.4:1.0, in which, the proportion of farmland is decreased from 47.9% to 38.8%, and the percent coverage of vegetation is increased from 20.6% to 47.6%. And the land-use structure gets rational. 2) Industry structure: The proportion of agricultural production is decreased from 79.6% to 54.8%, and the proportion of production in forest, husbandry and sideline is increased from 9.6%, 9.6% and 1.1% to 22.7%, 15.1% and 7.4% respectively. Industry structure trends to rationalization; and the rural economic development is orientated to diversification. 3) Consumption structure: The trend of change in consumption structure shows that, after comprehensive small watershed management, the supply of food, cooking oil and foodstuff, as well as the fuel and animal food is sufficient. Straws of grain could be able to return to field, and plants could be protected. Consumption structure apparently trends to direction that is beneficial to the protection of rural ecological environment.2. The condition of energy flow: The input of energy increases year after year. The ratio of organic energy to inorganic energy is reasonable. The efficiency of energy in 1990, 1995 and 2003 is 1.96,2.26 and 2.16 respectively.3. Changes in organic matter, nitrogen, phosphorus and potassium in the soil of field: 1) Organic matter ratio in soil in 1993 and 2000 is 0.91% and 1.095% respectively. 2) The result of the inputs of nitrogen, phosphorus and potassium subtracted by the outputs (including the output with the harvest and the loss soil and water) in 1990 shows that the deficits of N and K are 20.8t and 280.08t respectively, and the surplus of P is 13.38t. Afterwatershed management, due to the control of aimless input and the increase in the input of manure, the deficits of N and K decrease year after year, to 2.12t and 4.9t in 1995 respectively, and 0.54t and 0.87t in 2003, reaching balance approximately. The surplus of phosphorus in 1995 and 2003 is 22.421 and 24.4t respectively.4. The result of evaluation on benefit of investment: 1) Static indicator: the payback period of investment is 12.2 years, meaning the return of all investment in this watershed management at present; the ratio of benefit to cost is 3.82 more than 1. 2) Dynamic indicator: the economic internal return ratio (ERR) is 11.52% more than 7%; the economic net present value (ENPV) is 522 797 yuan RMB more man 0; the ratio of benefit to cost is 1.69 more than 1; the payback period of investment is 16.5 years. Both the static and dynamic indicator is in accordance with evaluation standards, showing that Litaiping watershed management is significant in economy.The above result of this research shows that the effect of Litaiping comprehensive small watershed management is significant. |
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