Research On Exploitation And Utilization Of The Geothermal Resources Of The Yellow River Delta Area And Its Influence On Environment

Resources and environment problems have become two largest strategic problems which the human faces in the 21st century. In recent more than twenty years, our social development and economic construction have made achievements which draw the focus of the world's attention, in particular, the coastal area has been leading the development our economy at fast speed, and also is the zone with the densest population of our country. The Yellow River is called"Mother River"in our country, with a lot of population along the drainage area, and people acts intensively there. With the implementation of West Development Strategy, the industrial and agricultural development as well as urbanization process of the drainage area of the Yellow River and Deltaic Region is greatly accelerated, and geothermal resource is supporting the economic development of the Yellow River Delta as an important energy resource.The geothermal resources are very rich in the Delta, however, no systematic research was made in the past and no attention was paid by the relevant departments, extent of utilization was very low. During the course of utilization of geothermal resources, low utilization and environmental pollution have become to be acute and serious problems more and more. This paper makes researches on the application of scientific theory and methods to carry out comprehensive utilization assessment and research work of environmental pollution and prevention and controlling, for the purpose of providing scientific basis for reasonable utilization of geothermal resources and protection of ecology environment, etc. as well as reducing the environmental pollution and impact caused by the geothermal exploitation and utilization, with an aim of sustainable development and with the leadership of intensive and economic utilization of resources.This paper fully collects materials on physical geography, geology, hydrology, ocean, resource development, remote sensing and environmental monitoring, etc. in the Yellow River Delta area, and makes researches on the general of region, regional geology and lithologic character, preservation character of geothermal resource, hydrology and water quality status character of local ground water, etc., and also makes comparison with the changes of parameters under the conditions of exploitation and utilization..The environmental problems occurring in the course of geothermal exploitation and utilization can be directly seen from the influence on the water quality of regional shallow groundwater, therefore, this paper makes special simulation and research. This paper researches to adopt the latest finite element method (FEM), to start from the variation forms of finite solution problems, and derive the corresponding system of linear algebraic equations by the Ritz—Galerkin Method, which has flexible dissection of mesh, small geometrical error, easy for dealing with natural boundary value condition, can keep conservation of mass and also create high accuracy forms. Based on the dynamic character of groundwater in the appraisal region, this paper takes the lowest ground water level dated June 22 in the low flow period of year 2005 as the initial level, which can be determined based on the observation data of the ground water level ,and takes the initial water level, boundary current and hydrogeologic parameter, etc. into the model by use of groundwater simulation software-Visual MODFLOW(module-type three-dimensional finite difference groundwater flow model) adopts SOR Method to calculate water level by use of unsteady fluid flow, and make matching by use of peephole water level and adjust the hydrogeologic parameter to make calculated value identical with the observation water level. In addition, take the most important fluorine element as the water quality simulation factor, and simulate the influence of fluorine element on the ground water.Water temperature is an important factor to affect the water quality process, such dissolved oxygen density, non-ion ammonia density and oxygen consumption coefficient and coefficient of aeration, etc. are related to the water temperature. The released hot water can form heat pollution, higher water temperature or faster changes of water temperature will affect normal growth of aquatic life and functions of water body. The changes of water temperature of water body can be affected by the pollution sources, and in addition, they have something to do with a series of heat exchanging process, including heat exchange with the air and that with the river bed, etc. This paper adopts computer modeling technique to make dynamic simulation for the changes of the temperature in the course of discharge of geothermal heat tail water, and establish forecasting model; through model recognition, to simulate dispersion, movement and cooling of heat in the course of discharge of geothermal heat tail water, forecast the heat of each calculated fractured surface under different discharge conditions, and then assess their pollution extent. However, due to the limitation of present research conditions, this paper only determines for the research region the forecasting model and computing method of changes of water temperature after the discharge of geothermal heat tail water to the rivers and lakes, temporarily without adoption of proper application data for operation in the example.Because there are many problems in the exploitation process of geothermal resources in the Yellow River Delta and also there is no reasonable and unified planning for the exploitation and utilization of resource, it is necessary to make whole dynamic planning for the exploitation and utilization of geothermal resources in the Yellow River Delta, make analysis on the problems in the geothermal exploitation process in the Yellow River Delta and take separate strategies for the existing problems in order to achieve the optimized effects. This paper has given the following solutions for the existing problems in the exploitation and utilization of geothermal resources in the Yellow River Delta, i.e., to design reasonable exploitation proposal according to the burial and distribution status; strictly follow the design exploitation proposal and allowed exploitation quantity for layer mining of geothermal water used for different purposes, and excessive exploitation is not allowed; during the course of exploitation of geothermal resources, make dynamic monitoring for the geothermal water, and find out the changes of water level, water quantity, water quality and water temperature, etc. during the course of geothermal exploitation, and make timely adjustments on the exploitation and utilization proposal and resources protective measures based on the monitoring information.In summary, this paper has analyzed the existing environmental impact situation in the Yellow River Delta area, forecasted the future development trend as well as put forward reasonable environmental protection suggestions and measures, which will be significant to enhance the comprehensive management and utilization of the geothermal resources in the Yellow River Resources, avoid continuing adverse effect on the environment, protect the favorable ecology of the Delta as well as revive the economy of the Delta.