Study On Pattern Of Utilization Of Rainwater And Flood Resources Through Groundwater Storage Space In Dalian City

Today the social economic is increasing quickly, the cities'scale is developing, the comprehensive function of the cities is becoming better and the people's quality of life is improving. Consequently, the demand of water resources will increase rapidly. And it is irresistible that the 21st century will face the crisis of short of water resources. The problem of short of water will become the greatest constraint in sustainable development of the society.Dalian city is located in the northern hemisphere with a warm, semi-humid continental monsoon climate. As to water resources, there is a sharp contradiction nowadays. On one hand, Dalian city is short of water, and the problem seriously constrains the development of the city. On the other hand, there are too many rainwater resources without human use, which flow into sea vainly in rainy seasons. There are several reasons contributing to the results. First, rainfall in Dalian city is quite concentrating. The amount of rainfall during June to September takes more than 75% of total amount of the whole year. Second, it is because of the geographical features, like the sharp topography, the bare physiognomy and etc. Furthermore, most of the river runoff is short in Dalian city, which flows into the ocean rapidly. According to the specific conditions in Dalina city, there has been no probability to construct large or medium size surface reservoirs. The only meaning way to store rainwater and flood resources is to use groundwater storage space. So it is significant to make research on the pattern of utilization of rainwater and flood resources with groundwater storage space in Dalian city.According to the research and practice in advanced countries, it is feasible to use rainwater and flood resources with groundwater storage space. Several countries, like America, Netherlands, Germany, Japan and other developed countries, have already adopted a series of laws and regulations on water use, and established groundwater irrigation systems, which may be composed of roof storage equipment and infiltration tank, well, lawn and infiltration equipments. These researches have provided good reference to the utilization of rainwater and flood resources with groundwater storage space in our country.Based on the collected information, the thesis first sums up the general condition of Dalian city, such as climate feathers, topography feathers, geological condition and hydro-geological condition. These data will serve the research of utilization of rainwater and flood resources with groundwater storage space.On the basis of previous studies, this thesis illustrates the indispensability of utilization of rainwater and flood resources from several aspects. These aspects include the increasing of water demand, the potential resources of surface runoff, the potential of groundwater exploitation, regulating water between water basins, controlling flood disaster and deterioration of water environment and other aspects. Flowingly, the thesis puts up forwards that it is feasible to use rainwater and flood resources in Dalian city, because of its rainwater resources potential, good hydrological and geological conditions and low status ratio of rainwater utilization. Then the thesis sums up the characteristics of rainwater and flood resources. And it calculates the amount of potential of the resources based on an experiential formula. The results show that the amount is quite large. There are about 31.6 hundred million cubic meters rainwater resources each year when the guaranteed ratio of precipitation is 50 percent. Of course, it will greatly contributes to the development of the society if fully utilized.On theoretical study, this thesis summarizes the concept of groundwater storage space. And it divided groundwater storage space into several categories in accordance with the media types that yield water. Then the thesis displays the regulation condition from the aspects of regulation water supply, regulation storage space and water renewal speed. After comparing with surface water reservoirs in Dalian city, the thesis sums up the advantages of groundwater storage space. As to different categories of groundwater storage space, the thesis puts forwards up the corresponding calculation formulas. Meanwhile, the infiltration condition is one important factor that directly determines the rainwater supply to groundwater storage space. So based on soil condition and vegetation condition, this thesis analyses the characteristics of groundwater storage space.In order to make the pattern of utilization of rainwater and flood resources with groundwater storage space as objective as possible, this thesis presents an evaluation index system. Of course, the factors selected in the evaluation index system should have certain physical meanings. Furthermore, the factors should distinguish each other from view of mathematical angle, such as try to make them seem accordant in a same region and seem different between different regions. Finally, this thesis selects 16 indexes in four areas. These four areas include characteristics of rainwater and flood resources, characteristics of groundwater storage space, environmental elements and social elements. Using principal component analysis, the thesis finally selects four main factors as principal components, including amount of rainwater and flood resources, type of groundwater storage space, infiltration condition and extent of urbanization. And the result covers more than 85% information, so it is feasible.As we know, it is significant for us to establish a pattern of utilization of rainwater and flood resources with groundwater storage space. If it comes true, we will use rainwater and flood resources more rational, and we will minimize the negative ecological effects to a great extent. Based on the established evaluation system and the specific hydrogeological conditions in Dalian city, this thesis divides the pattern of utilization of rainwater and flood resources into 9 models. These models include rich water area-valley pattern, average water area-river valley pattern, poor water area-river valley pattern, average water area-karst pattern, poor water area-karst pattern, rich water area-bedrock fissure pattern, average water area-bedrock fissure pattern, poor water area-bedrock fissure pattern and city area pattern. Combining the characteristics of each pattern, the thesis explains the corresponding pattern for utilization of rainwater and flood resources.Through the analysis, we can conclude that there are some differences between the river valley area rainwater utilization pattern and karst area rainwater utilization pattern. The main difference is that the former pattern mainly needs cone of groundwater depression which is resulted from human water drawing. And in this way, there will be enough groundwater storage space to store rainwater and flood resources. But the latter pattern is usually close contact with seawater intrusion. Therefore, the latter pattern emphasizes on storing water rather than mining water in order to prevent geological disaster. Meanwhile, the pattern used in rich water area emphasizes on infiltration and storage, but the pattern used in average water area and poor water area focuses on increasing groundwater storage space to store rainwater and flood resources.In short, rainwater and flood water have brought tremendous disasters to human beings, but beyond their disaster characteristics, they also have useful characteristics as resources to some extent. It means that rainwater and flood have dual characters as disaster or resources. Along with the problem of shortage of water becomes worsening, more and more hydrologists begin to pay attention to the issue. The meaning to establish the pattern of utilization of rainwater and flood resources with groundwater storage space is to direct better use of water resources. In the guidance of water resources system, we can know the hydrological and hydrogeological conditions, urbanization and environmental effects better. Also we can do comprehensive analyses, and try to make use of rainwater and flood accordant with protecting environment. In this way, rainwater and flood resources can provide the theoretical and technical support to the society development.The pattern of utilization of rainwater and flood with groundwater storage space has provided guidance to efficient and reasonable use of the resources. In a whole, in Dalian city, through locating rainwater utilization projects, strengthening scientific management, achieving optimal allocation of water resources, we can make better use of rainwater and flood water. Meanwhile, utilization of rainwater and flood through groundwater storage space has other advantages, such as save the investment, ease the contradiction between supply and demand of water resources. And also, it will minimize urban flood disasters and mediate the city's ecological environment.