Index weight analysis of groundwater function evaluation and zoning system in arid areas

Abstract: The most striking characteristic of an arid climate is a lack of moisture with the low precipitation, while strong evaporation, particularly in northwest China. In the natural lake wetland, the growth state of natural vegetation and the quality of basic farmland are strongly dependent on the groundwater burial condition. Therefore, this study aims to propose a set of groundwater function evaluation and zoning, to establish a novel evaluation system for the groundwater function in arid area. 4 layers were divided, including from high to low (marked as the system target layer), criterion function layer, attribute index layer, and factor index layer. Specifically, 14 indicators were set in the evaluation system. A step to build the system was as follows: To combine the logic and multi-objective indicators, attributes classification, function aggregation, and unique system, called "dry area system" for short. The requirement and standard for the evaluation of the groundwater condition were generally associated with "Technical requirements for evaluation and zoning of groundwater functional zones" released by China Geological Survey Bureau in 2006, where the indicators are guiding the evaluation and division of groundwater function in North China, northeast China, Shanxi great Basin and northwest China. Compared with the previous edition, the "dry area system" mainly expressed the indexes of "Arid area system", representing the essential characteristics of groundwater in northwest China, further to pose the new connotation on the attribute indexes of a system, with the removal the number of less common indexes. Specifically, 22 indicators were reduced to 14 factors, with the addition of some new indexes, including the attribute index of "natural wetland landscape maintenance", the factor indexes of "wetland environment and groundwater correlation", "oasis coverage and groundwater correlation", and "desertification and groundwater correlation". In this study, an index weight method of "Arid area system" was proposed using the sequence synthesis mathematical theory, and the analytic hierarchy process as the theoretical framework. The original data was selected to serve as the basis of weight evaluation, according to the principle of index weight analysis, including the critical, correlation, systematic evaluation. The index weights of 14 factors were then analyzed in factor index layer. Based on the indexes of possession, renewal, availability, and ecological function of groundwater resources, the weight of groundwater resources function and ecological function in arid area was elucidated to fit in the northwest inland groundwater function of the natural properties. The application in Shiyang River Basin showed that the "Arid area system" was feasible for the groundwater function evaluation in arid area. The evaluation data was also suitable for the essential characteristics of groundwater resources and ecological function in different areas. The finding can provide a sound theoretical basis for fine management groundwater and ecological protection, and thereby to support rational development of groundwater and targeted management of ecological protection in arid areas.