The Study On Sustainable Development Of Soil And Water Conservation

Based on the theory of sustainable development, the dissertationcombines with the national science and technology key project, takes small watershed in hilly-gully region of loess plateau as the field of research. The theory of sustainable development of soil and water conservation, analysis of watershed sustainable development, environment system of soil and water conservation, regulation of watershed system, development of land production, monitoring and evaluation of watershed system and watershed management information system arc studied systematically. The study achievements have important significance on theory and practice for sustainable development of soil and watershed conservation in China.1. The concept of sustainable development of soil and water conservation is advanced firstly and the theory basis, content, methods, evaluation and its index of sustainable development of soil and water conservation are discussed. Also, the basic approach for sustainable development of soil and water conservation in China is put forward.2. A large of data is acquired by using large-scale device of artificial precipitation. The runoff mechanism aroused on slope is analyzed in terms of basic equation of Kinemetic Wave theory and model of soil erosion on slope varied with time and space and of parameter prediction are set up. On the basis of study mentioned above, the computer-based simulation model of soil erosion of watershed coupled with CIS is built. The simulation model based on analysis of topographical feature of DEM, the hydrological analysis of runoff in watershed is conducted and the soil erosion of watershed is operated. The soil erosion simulation is conducted from the rudimentary cell to the patch of land utilization and to the whole watershed and from each rainfall to the whole year and these make the soil erosion simulation distribute spatially and temporally. The results could be applied in determining the source of sediment and pollution matter and has great significance in soil and water conservation, pollution and pediment control.3. Under the guidance of the SPAC theory, the factors such as rainfall, infiltration, transpiration, evaporation and soil moisture so on were observed systematically and the methods of time series analysis, Horton infiltration model, harmonic analysis, Grey cognition analysis, water balance principal were applied in studying the rainfall law, soil infiltration function, plant transpiration, soilevaporation and the law of soil moisture varies with time and space of watershed. The results are as follows,(1)the inter-annual rainfall variation is periodicity, and the variation period is 132 months, about 11 years, (2)the soil infiltration function is improved by control measures and the amount of soil infiltration is increased by 30% in average of woodland and grassland and by 62% in average of terrace than that of slope-land, (3)the reception amount of rainfall in soil can not meet the need of consumption of transpiration of tree and grass. (4)thc water utilization rate of woodland and grassland is larger than the farmland, (5)the yearly soil moisture variation can be divided into four periods in the watershed, namely the slow soil moisture evaporation period in spring from the early April to the middle ten days of June; the serious soil moisture deficiency period in dry season from the middle ten days of June to the middle ten days of July; the soil moisture supplement period from the middle ten days of July to the middle ten days of October; the relative stable soil moisture period in the spring and winter from the middle ten days of October to the end of March of next year, (6)the retaining capacity of soil moisture in woodland and grassland is larger than in farmland and the amount of retaining capacity of soil moisture of watershed under different type of precipitation after control is larger than that of before control, (7)the 7 soil moisture prediction models with different land utilization and plant cover were set up by applying water balance principal and all models have high precision of prediction by been tested.4. With the methods of Bowen ratio-energy balance and stand investigation, the microclimate effect and productivity of Larix Principis-rupprechtii Mayr. were studied. The results show that the average albedo of Larix in arid area of loess plateau is ranging from 13.4% to 20.5%, grassland is from 17.1% to 22.3%, bare ground is from 23.8% to 34.6%. The temperature in the stand is lower than the outside of stand obviously and has less difference of daily temperature. The average ratio of Bowen in the growing season of stand is 0.54, less than the grassland and bare ground and has good effect of improving microclimate. Water is a key factor on limiting plant production. In order to raise wood productivity, reducing afforestation density and enhancing management are proper measures.5. The theory, method and approach of watershed system regulation arc put forward. The model of system regulation by using SD method is set up and applied. The regulation measures such as birth control and introducing new agriculture technology are fit for practice. The study results of population quality impact on economic development of watershed show that population quality bas taken important role in watershed economic development and labor physics is still a main factor under poverty-stricken area. The intellectual level ofpopulation has great effect on economic development.6. A series models of crop potential productivity were formed on the theory of degradation of energy and system engineering, and verified by the reaction of crops to climate with actual results and Delphi method and the results showed a good reliability. The results indicate that terrace has the largest potential productivity, steep slope land has the least and gentle slope land is in the middle. The effect of soil moisture is getting less important form terrace to steep slope land. The present yield of spring-wheat, potato, bean and sesame is only 34.4%, 44.5%, 18.3%, 58.2% of potential productivity and that implies much potential to be developed in the future. The natural factors limiting crop production arc soil nutrient, moisture and temperature which effective coefficient in terrace of spring wheat is 85.7%, 53.1% and 36.9%; 96.1%, 33.2% and 50.4% of potato; 81.6%, 52.4 and 39.2% of bean; 73.1%, 41.8%, 52.1% of sesame and the economic management factors arc species improvement, soil amelioration, cultivating management and new agriculture technology application. Based on above results, the approaches for developing land productivity arc presented.7. The technology system of land productivity development, which includes improvement of productive condition technology, building up and applying fertilizer technology, tillage technology for withstanding drought, inter-cropping technology, introducing good species of crops, application of bio-chemical products was set up by the research of plot experiment and demonstration. The yield of crops will be get raised differently by adopting above technology.8. The monitoring theory of watershed was put forward. The content of watershed monitoring was divided into four groups, which include 40 items. Based on the results of ecological subsystem monitoring, the drought prediction model was set up and shows a good precision. The human activities have great effect for decreasing runoff and sediment. The different prediction and regulation models were gotten by the results of economic subsystem monitoring. The index system for evaluating human living quality is set up and the results show that human living quality in the period of the eighth five-years plan is increased 18% comparing to the year of 1990.9. The index systems for evaluating both watershed management benefit and sustainable development. The results of benefit evaluation show that the ecological, social and economical benefit is getting increased and is increased 11.8% comparing to the year of 1990. The results of sustainable development evaluation show that Huangjiaercha watershed is in the middle stage of sustainable development. The stages for describing sustainable development are the unsustainable development, the critical stage of sustainable development and the stage of sustainable development, the stage of sustainable development...