Study On Spatial Simulation Of Surface Hydrological Processes Under The Influence Of Coal Mining In Changhe Watershed Of Shanxi Province

The Changhe Watershed is a typical loess hilly area,which located in the southeast of Shanxi Province.The coal mining industry and related industries have made great contributions to the local social and economic development.However,a large number and long-term coal mining has caused many environmental problems such as surface subsidence,vegetation destruction and groundwater loss,which have seriously affected the normal life of local people and the development of social economy.Coal mining has changed the surface morphology and damaged the original hydrological process on the ground,which has affected the healthy development of the ecosystem.Therefore,the study of surface hydrological processes under the influence of coal mining in the Changhe Watershed,which has great practical significance to protect the environment,reconstruct the ecological and scientifically mining in coal mining area.The paper is to study the surface hydrological process under the influence of coal mining in Changhe Watershed,we constructed the rainfall interception model of natural vegetation and planting vegetation,soil infiltration model based on improved Green-Ampt model and runoff confluence model by using digital elevation model to established digital water system.Based on the analysis of multi-year rainfall data in Changhe Watershed,we set up three different rainfall intensities to simulate the surface hydrological processes in the study area.Used the maximum value composit,unitary linear recursive analysis,coefficient of variability analysis,descriptive statistics analysis,geostatistics analysis and intercomparison of mining area and non-mining area.These methods were used to qualitatively and quantitatively study the effects of coal mining on the vegetation and soil in mining area.The results showed that:(1)In different rainfall scenarios simulation:when rainfall intensity was 2.5 mm/h,most of the rainfall was intercepted by the vegetation and less infiltrated into the soil;when the rainfall intensity was 8 mm/h,the vegetation canopy interception reached the maximum in 1 hour.After rainfall intercepted by vegetation and soil infiltration.The runoff is hard to form on the surface;When the rainfall intensity was 16 mm/h,rainfall forms surface water and confluence in a short time,accumulation increases gradually from north to south and reached the maximum at the southwest exit of the watershed.The sub-watersheds in the mining areas are denser than those in non-mining areas.And the amount of vegetation interception and soil infiltration shows that the mining area is smaller than the non-mining area.(2)The overall vegetation change tends to be improved in Changhe Watershed from 2000 to 2015.62.000%of the area has been improved,15.583%of the area has been degraded.The proportion of degraded area of vegetation in the mining area is 23.573%,which is 6.255%more than that in the non-mining area.After 2007,the vegetation degradation area in the mining area was reduced by 4.995%compared with the previous period.The improved area is located in the scope of coal mining.The degree of interference of the coal mining on the vegetation in the mining area has weakened.(3)The generally stability of vegetation shows a pattern of stable and fluctuating coexistence.The eastern and western regions are more stable than the middle.The variation coefficient of the vegetation between the mining area and the non-mining area is 0.4%.The highly unstable regions are concentrated in the scope of coal mining,and the interference of coal mining to vegetation is still continuing(4)The soil saturated hydraulic conductivity in the Changhe Watershed shows a clear spatial distribution pattern.The soil saturated hydraulic conductivity of the mining area is generally less than that of the non-mine area.Kriging spatial interpolation results show that the average soil saturated hydraulic conductivity in the mining area is 34.375 cm/d less than 44.426 cm/d in the non-mining area,and the area with low soil saturated hydraulic conductivity is the core mining area of the coal mine.