The Study Of River Classification And River Habitat Assessment In Liaohe River Basin

Since 1950s, human population and economic has been increasing continually, and science and technology developing rapidly. Meanwhile, the exploitation and utilization of river become increasing serious. Thus, the structure, functions and habitats of river ecosystem are damaged. The carrying capacity of river is becoming more and more inconsistent with human population increase and economic development. River management encountered with great challenge. The root cause of this phenomenon is that people manage rivers based on huaman requirement, ignoring the ecological demands and habitat conditions of river, and do not take river types and functions into consideration, which results in the serious influence on river ecosystem. River habitats are the most important parts of river system, and also the necessary requirement for constituting river ecosystem integrity and maintaining river health. They are important foundation for evaluating river health and river management, and have practical significance. Based on these, the paper selected the Liaohe River basin as the research object, and established the river classification method at river reach scale. The empirical research of river habitat assessment was carried out according to the results of classification. The purpose is to provide reference for the development of river habitat assessment and for ecological protection, restoration and renovation of river. Major results are as follows:(1) An index system for river classification was established at reach scale, including stream order, confinement degree, channel numbers and sinuosity. The hierarchical classification method was established by top and down. Different river types were named as the following rules:confinement degree (confined, partly confined and unconfined)+sinuosity (light sinuosity, moderately and high sinuosity) +channel number (single channel and double channel)+stream order (main stream and tributaries).3158 reaches in Liaohe river basin were divided into 20 river types.(2) Empirical investigation in the wild was carried out according to the classification results. Referring to the river fast assessment system of USA EPA, some sampling points for river habitat assessment research were set up at each river type. The assessment results showed:there are 479 valid points, and the comprehensive index scores of river habitat survey are between 27 and 192. The habitat quality of 38.5% sampling points is better or good, mainly distributed in Hun river and Taizi river and the main stream and tributaries of Liaohe river; The habitat quality of 45.7% sampling points is normal, mainly distributed in most basin of Liaohe river; The habitat quality of 16% sampling points is more poor or poor, mainly distributed in the mid-and downstream of Hun river and Taizi river.(3) The difference of habitat quality among different river types and the influential factors were analyzed. The results showed that there are not significant differences among 20 river types. But significant differences analysis based on classification results showed that habitat quality in rivers with different confinement degree, sinuosity, channel number and stream order were significantly different. River habitat encountering some questions, including unstable river banks, small river width, poor vegetation condition, strong developed of floodplain, serious human disturbance and poor aquatic vegetation et al.In view of researches on river classification and river habitat assessment in our country is still at the elementary stage, this study established a river classification method and river habitat assessment system at river reach scale. The selection of classification indicators, assessment indicators, assessment criteria still require further river ecological investigation to improve the assessment system and the reliability of results. The study was mainly carried out at macro-scale, and didn’t study the questions at micro-scale. So multi-scale research should be taken to know the influence mechanism of indicators in river habitat and evaluate the river quality habitat more accurately.