Soil And Water Conservation Ecological Reconstruction Mode For Mining Waste Land In Liaoning Province

Liaoning is one of the major mining industry provinces in China, and mining industry makes outstanding contributions to its economic development and comprehensive national power increase. However, soil loss in mining area was increasingly intensifying and ecological environment suffered rapid degradation because of long-term overlooks of environmental treatments. Thus, they cause people's health hazard and property safety damage severely.This study aims to provide technical support of mining waste land ecological reconstruction for Liaoning Province. By surveying the current status of environment destruction in mining waste land all over the province, restrictive factors of ecological reconstruction were determined using AHP analysis. Moreover, some effective and practical techniques of ecological restoration and reconstruction for mining waste land were putted forward. Some conclusions were obtained as follows.They are 89553.64 ha mining area in Liaoning Province, which produces 132.5 million cubic meters of solid waste material emissions per year. In these areas, the yearly total amount of soil loss is up to 11.79 million tons, accounted for 69.5% of those in strong erosion area of Liaoning Province. Average erosion modulus in mining area is 4.6 times (13161.38 tons per kilometer per year) of that in the province.Factor analysis showed that ecological environment deterioration of mining area was caused by some reasons as follows:1) vegetation destruction. The vegetation coverage of open pits, waste rock fields, and tailings reservoirs is almost zero, and the vegetation coverage of surrounding area for underground mining pits after exploitation decreases 19% than that of pre-exploitation; 2) ground slopes increase. The slopes of mining stopes and waste rock fields are high to 52 degree and 41.4 degree, respectively, which being almost two times of those of pre-exploitation; and 3)soil structure destroy. Water conservation capability of rock soil becomes weaker and weaker after exploitation. The soil moisture is lower from 6% to 11% than that of pre-exploitation, and its increasing amplitude after fully rainfall is relatively lower, for an example, water content of coal gangue is less than 8.0%.AHP analysis suggested that dominant factors impacting on ecological reconstruction of mining area are precipitation, soil grade composition and substrate weathering velocity, respectively among all 14 factors. So, these 3 factors should be mainly considered during ecological zoning and reconstruction for mining area. There are 3 first grade,5 second grade and 7 third grade regions for mining area in Liaoning Province. Among first grade regions, the amount of mining area in water erosion region accounts for 94.5% of that in the province, and damage area in this region is up to 96.2% of that all over Liaoning.Moreover, five ecological reconstruction modes are proposed according to substrate characteristics of mining area. These are economic forest mode without covering soil for soil substrate, ecological forest mode without covering soil for soil substrate, tridimensional development mode by promoting weathering and non covering soil for easy-weathering rocky substrate, ecological forest mode with covering soil platform field for uneasy-weathering rocky substrate, and ecological forest mode with carrying soil in concrete holes for uneasy weathering rocky substrate, respectively.