Study On The Assessment Pattern Of Risk And Benefits From Floodwater Utilization Through Underground Water-storing Space In River Valley Of Mountain Areas

Rational development and utilization of floodwater resources is the important way to solve water confliction. Using the underground storage-space to realize the floodwater utilization is one of measurements to solve the contradictions between supply and demand of water resources in north China's mountain valleys where the water resources is seriously short, and raising the level of floodwater resources utilization also can meet the demand to water resources of the socio-economic development. Underground reservoir has become the effective measures and basic means to resolve the crisis in the world, which has brought the enormous socio-economic and ecological benefits. As the water system is an open complex systems, and is accompanied by a variety of uncertainties, moreover, the risk of system is arose by uncertainties, all of which water system inevitably has a certain degree of risk. So, realizing the floodwater utilization by the underground storage-space can not only obtain a certain degree of efficiency, but also take on part of the risk. Studying the risks and benefits in the process of floodwater utilization is imperative to the relationship between water resources and human socio-economic sustainable development.As for the assessment to the risks and benefits of floodwater utilization, there has been large amount of scientific research in the field of water science, the research and engineering to floodwater utilization using the underground storage-space has achieved considerable fruit. But so far there has no further research for the assessing mode to risks and benefits of floodwater utilization using the underground storage-space, especially for the sources of floodwater utilization using the underground storage-space, the mode of floodwater utilization, the assessment to the risks and benefits of all modes and so on.Based on the task "the mode research and demonstration of floodwater utilization using the underground storage-space " (2006BAB14B04), which is the fourth task of "11th Five-Year Plan" National Science and Technology planning key project—"the use of rainwater resources, technology research and application of floodwater utilization " (2006BAB14B00), and guided by the concept of sustainable utilization of water resources, the paper firstly the mode of floodwater utilization using the underground storage-space, defines the influencing factors of its mode, and determines its determining standard, all of which provides the foundation to floodwater utilization in the mountain valleys. Based on the research to the floodwater utilization using the underground storage-space and its risks and benefits, the paper studies the theoretical system of risks and benefits of floodwater utilization using the underground storage-space. And combined with its utilizing mode, the paper studies the assessing mode to floodwater utilization using the underground storage-space in the mountain valleys, which promotes process of the sustainable utilization and management of water resources in the way of theory and methods.Paper combined with a typical intermontane valley in the north China area-topography, geomorphology, meteorology, hydrology, stratum and lithology, geologic structure of Chaluhe River Basin, analyzed three-water conversion models and laws of the intermontane valley area. And according to the present stage water resources development and utilization status quo, the proportion of its water distribution, had pointed out that the development and utilization of water resources problems. The surface water is active in the region water cycle, exchanges the materials, information and energy frequently both within and outside of regional water resources system. Had analyzed Chaluhe River Basin flood characteristic and discussed the underground storing space structural feature of the river valley area. Based on this carried on two aspects the research: First, studied the intermontane valley area flood resources potential assessment method, combined with the research area flood resources characteristic, evaluated the potential flood of resources and proposed the measure and the way of floodwater utilization. Second, to study the assessment method of water resources regulation and storage capacity of underground water-storing space. In the aforementioned study, evaluated water resourses regulation and storage capacity of the underground storing space of the reach area.The main influencing factors of regulation and storage capacity of the intermontane valley area underground storing space include storing space, seepage condition, recharge water source, in-taking water condition, purchasing and replenishing condition, storage and adjustment function, storage and adjustment Index Control. Regulating space is skeleton and function carrier of the underground storing space. The total regulating space that can be used in groundwater reservoir area of Chaluhe River Basin is 6.5×108m3 in theory, development potential is 1.362×108m3/a. From regulating space, it is theoretically feasible that the realization of underground storing space rainfall flood resources in Chaluhe River Basin.Combined with potential quantity of flood resources and regulation and storage capacity of the underground storing space, discussed the use way and the influencing factor of the underground storing space flood resource utilization, Mainly included rainfall flood resources, the size of the underground storing space, rainfall flood seepage condition and urbanization degree. And according to recharge and development overall planning, water resources transformation, groundwater flow quantity pondage action, water quality and ecological environment protection, Classfied the simple explicit principle to divide 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. The above basic research lays the foundation for the intermontane valley area underground storing space flood using risk and the benefit appraisal pattern's research.In the above research foundation, take the system theory as the instruction, follows the sustainable development idea, have carried on the underground storing space flood use risk and the benefit appraisal theory research. Its system info mainly includes underground storing space flood use risk factor recognition and quantitative assessment, underground storing space flood use benefit recognition and combined earnings analysis, underground storing space flood use risk-benefit overall assessment, underground storing space flood use risk control policy and technical program.Underground water-storing space is to use a rock gap in the natural or artificial form of water storage structure as underground water storage and regulation and storage space. Flood resources in the form of the use of floods covering groundwater is one of the measures to to make full use of the water storage space to achieve rainwater resources. Underground water-storing space for the development of the risk system is groundwater system and the social, economic, ecological systems, interaction, cross-cutting posed a certain structure and function of complex systems. The flood using risk underground water-storing space means in the use of a particular time and space environmental conditions, the water resources system and its surrounding environment and in the process of human activities potential non-expectations event caused by the extent of the damage.Underground water-storing space for the risk sources of flood using is very complex, including natural sources of risk, the risk sources of pollution, the risk source of ecological environment, the social risk source, engineering risk sources.Underground water-storing space for the risk sources of flood using system has a comprehensive system with integrated, space and the difference of level, multi-objective, and self-organizing adaptive characteristics. Construction of water storage space on the ground floor for the use of rainwater resource, has a good resources effectiveness, economic efficiency, environmental and social benefits. Effective of use of the flood of underground water-storing space from different points of view can be divided into functional efficiency and overall efficiency, effectiveness of direct and indirect benefits, tangible and intangible benefits effectiveness, and efficiency being a negative efficiency, effectiveness and financial efficiency of the national economy.The core of the security the exploitation of water resources requires the development of man and nature in harmony, that is water-related social, economic, ecological, resources and the environment in harmony, the risk evaluation index system of water resources development and utilization must reflect this thinking. On the basis of underground water-storing space on the risk theoretical research of using flood development, to build an underground water-storing space for the use of flood risk evaluation index system. Index constituted by the three levels: aim level, rule level and single evaluation index level. The 29 indicators of index system covered by the assessment of the impact of floods underground water-storing space using risk are the natural factors, environmental factors, ecological factors, social factors and economic factors. The index system for underground water-storing space laid a foundation for the use of flood risks and assess the effectiveness of research.Underground water-storing space for the use of flood risk assessment belonging to the multi-criteria and multi-level comprehensive evaluation problem, involving a wide range of factors, many project-evaluation and some of the assessing factor itself is full of random, fuzzy and uncertain. Based on the particularity of underground water-storing space for the use of flood risk assessment, paper puts forward the mutation of multi-criteria evaluation of the law based on the mutation theory. The mutation evaluation absorb the advantage of AHP and fuzzy evaluation method, the subjectivity has been relatively reduced when working on the establishment and measurement of index. The multi-criteria evaluation based on the mutation theory through all the contradictions of the factors normalized, getting the corresponding mutation fuzzy membership function. In a complex analysis of the system evaluation, only to the various conflicts in accordance with the factors according to the importance to sort, and determine the weight without any subjective. This method can be used in complex systems evaluation system. And compared with other methods.The mutation evaluation tend to reality and has some advantages, such as shortcut calculation, precise outcome and convenient application.Reasonable and effective use of underground water-storing space for the realization of rainwater resources can generate substantial economic benefits, a significant ecological and social benefits, underground water-storing space with the use of flood has a certain economic rationality and macro-feasibility. The main process of underground water-storing space for flood-using effective assessment: the first step was to identify efficiency; second was to classfied the effectiveness; the third step was to calculate to quantify; fourth step was to analysis of the evaluation. Through the establishment of effective quantitative model for the further development and utilization flood resources provides a reliable technical support, but at the same time need to recognize that the flood resources itself is in a long-term, non-stable water resources, to use its must do full risk of loss analysis, in the framework of sustainable use it.In short, the papers from the strategic perspective of sustainable development, based on the sustainable use of water resources, to explore underground water-storing space for the risks of using flood and the benefits assessment model, for the promotion of sustainable use of water resources and management, the development of healthy ecosystems has important theoretical and practical application.