Estimation Of Land Surface Evaporation In Shanxi Coal Bases And Analysis Of Its Differentiation Rules

Shanxi Province coalfields include three sub-coalfields: Jindong, Jingzhong, Jinbei. This region, locating in the Loess Plateau Region, has a typical temperate arid to semi-arid continental monsoon climate and a fragile ecological environment. The frequent underground mining activities have destroyed the underground water system and the underground water system is almost exhausted. The surface evapotranspiration is not only an important part of the regional water balance and energy balance, but an important link between ecological process and hydrological process. Therefore, accurate estimation of surface evapotranspiration in Shanxi coalfields can help to relieve the regional contradiction between supply and demand of water resources, increase the utilization rate of water resources, allocate the water and soil resources efficiently and provide theoretical support to make the land use and eco-environment protection plan rationally.This study based on quantitative remote sensing evapotranspiration model – SEBS(Surface Energy Balance System), data resources of NOAA/AVHRR、DEM and meteorology, etc., using ENVI、ARCGIS software, to quantitatively estimate the surface in Shanxi coalfields and establish the conversion model of actual evapotranspiration and the observation evapotranspiration of the weather station. According to the linear fitting relationship between the actual and the observed evapotranspiration of the weather station, the evapotranspiration of each month and the whole year in 2013 was estimated. Meanwhile, the relationship between evapotranspiration and the influence factors – temperature, precipitation, vegetation index and land use/cover was analyzed.Results show that:(1) the maximum of surface evapotranspiration appeared in July, about 6.06 mm/d, and the minimum of surface evapotranspiration appeared in December, about 0.32 mm/d;(2) the total annual surface evapotranspiration in Shanxi coalfields is about 736.55 mm;(3) the annual surface evapotranspiration presents a distinct seasonal variation, and the order is summer > spring > autumn > winter;(4) surface evapotranspiration increases with the temperature, and there is high correlation between them, with a correlation coefficient more than 0.9.(5) the variation trend of evapotranspiration is similar with that of, buts a little later than precipitation.(6) evapotranspiration and vegetation index were significantly positive correlation. According to the relationship between evapotranspiration and NDVI, the study area can be divided into three patterns: bare zone(NDVI<0.12), common area of bare land and vegetation(0.12<NDVI<0.73).(7) surface evapotranspiration on different land use is significantly different from each other, and the order of total value is: water> forest land> farm land > grassland > building land > unused land;(8) the order of sensitivity of evapotranspiration in different land use/cover to the seasonal variation is: farm land > forest land> grassland > water> building land > unused land.(9) 6.262 billion cubic meters of water could be reduced every year when reclamation of all bare land is finished in open-pit mine in Coal base of Shanxi Province.