Watershed-scale Spatial Management Based On Evaluation Of Comprehensive Water Carrying Capacity

In order to balance the contradiction between social and economic development and water ecological environmental protection,and effectively control the spatial differences in the basin,realize the high-quality sustainable development of the basin,it is of great significance to study the water environmental comprehensive carrying capacity(WECCC)of the watershed and carry out the spatial control of the river basin.As a complex human-water coupling system,WECCC is affected by multiple factors such as water environment,water ecology,water resources,social economy and technical management,and its evaluation process is often full of fuzzy uncertainties.There are significant differences in environmental resource endowments and economic development levels between the upper,middle and lower reaches of the basin,which makes the evaluation process of WECCC in watershed face different special extreme situations existing in between indicator values.The Variable Fuzzy Pattern Recognition(VFPR)model can realize the continuous evaluation of the complex system from part to the whole.When dealing with the fuzzy uncertainty of the evaluation process,it can consider the impact of different levels of membership,retaining more original information of the sample in the result.This can effectively identify the difference between similar result values,so it is very suitable for the evaluation of watershed WECCC.However,the traditional VFPR model still has some shortcomings.Firstly,the traditional method of taking the average of four different VFPR models as the result in the past cannot correctly reflect the differences between samples and the actual situation of the samples when the difference in indicator values between samples is extremely significant.Secondly,the traditional VFPR model cannot identify the situation where the sample is completely subordinate to a certain standard,that is,the recognition mode is incomplete,which makes the logical rigor of the model structure lack and limits the application scope of the model.In addition,there are few researches on watershed spatial management and control based on water environment comprehensive carrying capacity,the research space of the application to support the spatial management and control of the basin,and there is still room for expansion in the application of the evaluation results of the water environment comprehensive carrying capacity to guide practice.Therefore,in view of the fuzzy and uncertain characteristics of the watershed WECCC evaluation process and the extremely significant difference in sample index values caused by the spatial differences of the watershed,this paper constructs the watershed WECCC evaluation index system and proposes the WECCC evaluation based on the improved VFPR model This method is applied to the evaluation of the Dongjiang River Basin in Guangdong Province in WECCC.Based on the results of the evaluation,the basin is divided into different spatial development-oriented types,and the significant types of water problems in the basin and the types of water functional advantages are identified,which is a reasonable layout and development for the future economic development of the basin.The differentiated management of the water environment provides a scientific basis.The main research conclusions are as follows:(1)The VFPR model parameter improvement test group case results in this article show that when the sample index value goes beyond the standard range,the average value of the four models and the results obtained by the model 2 and model 4 and the actual change of the sample index value Inconsistent,because when the parameter p=2,the VFPR model directly defaults that the index value changes in a good direction;when the sample value continues to exceed the standard range in a better direction,the result obtained by model 1does not match the actual change of the sample index value.Therefore,model 3 is selected for the case study of this article.(2)This paper takes into account the uncertainty of the index value,applies the constructed index and method system,and evaluates the pessimistic and optimistic WECCC in the study area.The results show that the WECCC in the Dongjiang River Basin of Guangdong Province has obvious spatial differences.In general,the WECCC in the upstream regions is better,while the developed regions in the downstream are very poor.Among the three dimensions,the overall water resources results are the worst,which is the main limiting factor for WECCC;the water environment results are generally good,especially in the upper and middle regions,but the results are worse in the downstream developed regions;the results of the water ecology evaluation are in large areas.Some areas are at an acceptable level.The analysis of the instability index shows that Boluo’s WECCC has great instability,followed by Huicheng,and Xinfeng has the highest stability.(3)Based on the results of the WECCC evaluation,this paper divides the basin as a whole into different spatial development orientation types,providing strong support for guiding the rational development of the basin space;and identifying based on the spatial pattern and interaction of water resources,water ecology,and water environment Four prominent types of water problems and four advantageous types of water functions in the basin space are listed,which provide a scientific basis for the realization of differentiated and refined management of the water environment,water ecology,and water resources of the basin.