Research On The Evaluation Model Of Shallow Geothermal Energy Based On GIS

Shallow geothermal energy is a kind of clean, renewable and valuable heat energy which is hidden below the surface within a certain depth range (<200m) in rock,groundwater and surface water.It is almost independent of the environmental impacts of climate change because of its energy from solar radiation and the thermal conductivity of the deep Earth, the temperature is relatively constant.Compared with other sources of energy, Shallow geothermal energy is more abundant and more widely distributed, the constant temperature energy has a broad prospects.Shallow geothermal energy evaluation involves complex factors affecting, so information of single element is not fully to determine the suitability of the regional shallow geothermal energy exploitation.In this thesis, there is a comprehensive consideration of the geological conditions, hydrological conditions, environmental conditions and other related conditions to determine the evaluation factor of the shallow geothermal energy in the study area.This thesis is based on empowerment theory of the analytic hierarchy process and entropy method, combined with expert knowledge to establish a comprehensive evaluation index system for underground pipe heat pump system and groundwater heat pump system.Among them, the ground heat pump system consists mainly of three aspects including engineering geological conditions, hydrogeological conditions, the nature of the temperature field and thermophysical properties, and groundwater heat pump system includes four aspects including the occurrence conditions, the dynamic characteristics, water chemistry characteristics and special areas.The paper use the analytic hierarchy process to determine the subjective weight value and the entropy method to determine the objectively weight values, finally, the minimum entropy principle to calculate the weight of a combination of both.The combination of the two methods makes them complement each other, so we get a more accurate index weights.On the basis of the calculated combined weights, the thesis established shallow geothermal energy comprehensive evaluation model and determined the ratings system of evaluation factors through rating by experts, and finally calculated Regional comprehensive score based on the comprehensive evaluation model.By integrating of relevant research data,establishing a spatial database and an attribute one,development of shallow geothermal energy comprehensive evaluation prototype system according to the comprehensive evaluation model may achieve shallow geothermal energy division by suitability fast, intelligent and visualization based on GIS and provide decision support for actual projects.