Simulated Study On Soil And Water Losses In Different Phases Of Resources Exploitation In Coal Mine Region

At present, soil and water loss has been widely concerned as one of the important environmental issues by the whole world. The accelerated soil and water loss induced by large-scale centralized exploitation and corresponding engineering construction, is the key research content of presently studies on soil erosion, which has been attracting extensive attention of many governments and experts. Shenfu-dongsheng coal mine area, be one of China's important energy base, located in the combined wind and water erosion at northern Loess Plateau, is a typical area of fragile ecological environment. With the exploitation of coal resources, the environment there has been greatly changed, particularly because the accumulated spoil and exposed bedrock which disturb the rock soil easily resulted in accelerated erosion under the local special meteorological and hydrological conditions, and consequently a series of serious environmental problems occured. Fragile ecological environment has become more vulnerable, so it seriously constrained the mine area's production safety and sustainable development.On the basis of an extensive investigation of the mine area's overall environment under the development and construction since 1990, the authors mastered the mining area's environmental changes due to the exploitation of coal resources. According to actual situations of mining material composition and bedrock's distribution, using the simulated rainfall technology and the simulated weathering experimental technology, combined with GIS, simulated rainfall experiments were conducted respectively on the un-disturbed slopes and accumulated soils of different years, and Liudaogou watershed in this mine area was selected to study on soil erosion prediction model for all the mine area. This work supplies new methods and measures for a study of soil and water loss management and reclamation.On the one hand, this project, can provide technical support for the Shenfu Dongsheng mine to control soil erosion effectively, on the other hand, it also can offer a theoretical guidance on soil erosion for the sustainable development of mining areas of China.The main conclusions of the dissertation included: 1) The soils accumulated in different years had different anti-erosion capabilities, and with the increasing of accumulation time, the vegetation covering rate and anti-erosion ability were enhanced gradually.2) If the time of accumulated soils were over seven years, the vegetation and anti-erosion ability had well recovered, and if the time of accumulated soils were over ten years, the vegetation and anti-erosion ability had recovered to be similar to primary soil. And the effective measures to control soil erosion of disturbed spoil mainly on enhancing soil compactility and recovering original structure characteristics. Furthermore, increasement of vegetation coverage and rapide recovery rate can reduce soil erosion availably.3) Runoff in microbial crust district were greater than the same rainfall conditions without microbial crust. The sediment runoff of microbial crust was more than the same period of no microbial crust, and the test area of microbial coverage of 46% carried out least sediment runoff. Microbial crust of accumulated sediment yield was smaller than the one of non-microbial crust.4) Regardless of the effects of wind erosion, the main factors that affected the weathering rate of pisha-sandstones were the lithologies (mineralogical composition, pore characteristics, cementation,etc), treatment conditions, arrangement of drying -wetting-freezing cycle, etc.5) The indoor immersion and non-immersion weathering experiments also revealed that throughout the weathering process in the region, the role of wind was greater than the role of water.6) By simulating model of field rainfall erosion modulus in Liudaogou small watershed, we found that there is intense soil erosion occurred on late accumulated spoil with erosion modulus 10 times more than original slope and the largest sediment yield under field rainfall simulation. Under the same situation, the greater rainfall intensity is, the greater erosion modulus is. On sandy slope, once producing runoff, the sediment concentration would be large, and the formation process of gully is vertical seepage—slope undercurrent—landslip.The innovated progress of this dissertation included: 1) Through simulated rainfall experiments with different rainfall intensitis carried out on the accumulated soils since mine area's exploitation, the rules of runoff and sediment erosion in the different accumulated soils of natural recovery have been obtained.This method improves our ideas to study on the soil and water erosion of disturbed soils since mine exploitation.2) On the foundation of summarization the current research, analysis methods of the rock weathering study have great breakthroughs and innovations. Instead of using a single analysis method, freeze-thaw analysis, temperature-change analysis, or chemical processes analysis, a new weathering simulation method was advanced, which is combined with X-ray, according to local environment features, and integrated with the cycle of freeze-thaw, temperature-change, and chemical processes.Through comparative analysis of rock weathering process under different environment, there's a great scientific importance on qualitatively and quantitatively studying the factors affecting pisha-stones weathering.3) Based on the softwares of ArcGIS 8.3 and Mapinfo 7.0, combined with ecological principles, the objectives of this paper were to obtain erosion modulus by field rainfall experiments in various ecological terrain units, and to predict soil loss in the whole small watershed. According to watershed runoff concentration principle, combinatorics principle, and weights analysis of environmental factors, which affect soil erosion of each ecological unit, we constructed the soil erosion prediction model. Then by conducting rainfall simulation in Liudaogou small watershed, the model was proved. The soil erosion ecological prediction model can reflect the spatial difference of soil water erosion more accurately in the Loess plateau with steep slope, small terrain plot and frequent rainstorm.