Study On Assessment For Health Degree Of Rivers And Lakesinmountainous City

Healthy rivers and lakes provide ecological and social functions.The river and lakehealth is being threatened by rapid urbanization which has changed the characteristicsof natural geography and conditions of social economy as well as degraded thewatershed environment and affected the functions of rivers and lakes. River and lakehealth assessment provide scientific basis for their management and ecologicalrestoration.This paper comprehensively reviewed the studies on river and lake healthassessment both at home and abroad,rivers and lakes in Liangjiang New AreaofChongqing were regarded as study objects, assessment for health degree of rivers andlakes in mountainous city were researched.Main researdh contents and results inculd:①Water environment characteristics of rivers and lakesin mountainous city wereanalyzed which includes six aspects: small watershed system of river and lake, thehydrology, morphology and structure of rivers and lakes are complicated and variable,rapid urbanization made a real difference to the rivers and lakes, the disjunction ofcomprehensive protection and land use, the point and non-point source pollutionareserious, and the function of rivers and lakes were changed and disappeared greatly.The body and influence factors from human activities of river and lake were concerned,The river and lake health concept was preliminary discussed as follow,“On thecondition of rapid urbanization, rivers and lakes can maintain reasonablestructure,perfect functions and secular stability, and have resistant and resilience tonatural disturbance and human-caused disturbance, the rivers and lakes have theunodstructed stream structure, good water quality, integrated biological diversity and thesocial water cycle did not affect the natural water cycle, the coordinated development ofthe systems of natural, ecological environment and social”.The connotation of healthyrivers and lakesof mountainous citywas explored in three aspects: healthy naturalstructure and ecosystem, healthy influence factors, and the persistence of health statusin space and time. The state of artificial system was defined as the health state, the bestaccessible condition(BAC) was chosen as the reference state of healthy rivers and lakesin mountainous city.②General framework of assessmentfor health degree of rivers and lakes wasanalysed from three aspects: the assessment way, framework of assessment system and assessment scale. Thehealth degree of rivers and lakes were dividedinto five health levelof excellent health, health, sub-health, ill health and extremely ill health.Twenty-sixindexes were chosen according to natural structure, ecosystem and influence factors ofrivers and lakes, thus the index systems of assessment for health degree of rivers andlakesin mountainous citywere built, and the meanings, the calculating formulas as wellas the health rating crites of all the indexes were also identified. Because of a lake ofavailable data, the analytic hierarchy process(AHP) was chosen to calculate weights ofindexs, assessment of fuzzy comprehensive, variable fuzzy and set pair analysis wereused to assess the health degree of rivers and lakes, thus the accuracy of assessmentresults was ensured.③Yulin River, Zhongzui River and Longjing Lake employing the index systemsand models described above, the health degree of those were assessed. It was found that:the healthdegree of Yulin River was higher, each reach in the degree of health orsub-health, the whole was in the degree of health.The health degree ofZhaojiaxiwashealth or sub-health, however, the lower reach of Zhongzui River was insub-healthdegree, the Zhongzui River was in ill healthdegree. Longjing Lake was in thedegree of health. The assessment results of different models were all valid, and theselection of index system, weight calculation and computing process of fuzzycomprehensive assessment model were programmed in MATLAB language, computeroperation of assessment for health degree of rivers and lakes has achieved, it makes theassessment process easier and more exactly.The research results of this paper could supply reference for the comprehensiveimprovementofrivers and lakes of mountainous, and the construction of a healthy watersystem of Liangjiang New Area.