The Study On Characteristic State Of River Water Environment System In Mountain Areas

This article selects a typical section of the river section of the western part of the Sichuan Basin to study the construction of multiple concrete overflow weirs and rolling buns and the construction of flood protection slopes in the river section.This may lead to the hydrodynamic balance of the urban river water environment system and the main water quality control of the water body change.The trend of indicators changes.Therefore,based on the river scales in the mountainous area,this paper investigates the basic environmental information of the water environment of mountain rivers and the basic structure of the water system,generalizes the river water environment system,analyzes the system structure of the river water environment system in the mountainous area,and determines the watershed The area of the water area is 228.5 km~2,and the length of the cross section of the research river is determined to be 11km.Then systematically analyzes the differences in the operating characteristics of water environment systems before and after human disturbances in mountainous rivers,analyzes the hydrodynamic characteristics in water environment systems,and trends in the main water quality control indicators for water bodies.It compares and analyzes whether the river reaches the water environment system due to human disturbance.Based on years of hydrological data,meteorological data and the spatial structure of urban river systems in the study area,this paper divides the river section under natural conditions into five sections.Under the current state,it is divided into 12 sections.Based on the analysis of the hydrodynamic characteristics of the river water environment system,the hydrodynamic operating characteristics were selected as the typical conditions for the rainfall period p=5 and p=2 hydraulic conditions and non-precipitation dry season.The research shows that the flow at each section presents a gradually increasing trend,and the trend of cross-section flow changes is proportional to the catchment area.The larger the catchment area,the greater the cross-section flow.The flow speeds of the natural rivers and current rivers in the non-drug situation of the river are generally the same.The flow speeds of the rivers are in the same condition.When the river is in the drowning condition,the flow velocity is increased with the degree of drowning and the flow velocity is smaller.At the same time,the particle size of each section of sediment starts to have a direct relationship with the flow velocity of each section.The larger the water velocity,the larger the starting particle size.Current Status Rivers Due to the characteristics of muddy water flow,in the event of maximum flooding,the sediment will hardly start and the large amount of suspended pollutants and organic matter carried in the water flow will settle to the riverbed.Due to the human disturbance of the water environment,the current state of the hydraulic retention time in the river reaches 319.1 minutes longer than the natural river.According to the hydrodynamic characteristics of the river section and the upstream monitoring data,the main water quality control indicators in the natural rivers and the current river waters were simulated by the S-P model,and the curves of BOD,DO and ammonia nitrogen along the current rivers and natural rivers were plotted.According to the trend of water quality concentration in the two conditions,it can be known that the self-purification capability of the water along the river is less than that of the natural river water.The human-induced interference changes the re-oxidation process of the water environment system,and the overflow depth increases the water depth under the hydraulic condition of the overflow,resulting in an increase in water depth.Changes in the main water quality control indicators of the water environment system have changed.In summary,the study found that due to engineering measures such as artificially building embankments,dam construction,and cutting straightness in the river research section of the river,the hydrodynamic characteristics of river hydro-environmental systems were changed during the process of scouring and silting,and the water velocity along the river changed while passing.The SP model simulation calculations found that the trend of changes in the main water quality control indicators in the water bodies of the study river segments changed.According to the study,we found that the characteristic status of the water environment system was changed and repaired through engineering techniques,such as river dredging project,control of siltation and opening of flooding,balance of erosion and siltation,selection of materials for river slope protection,and multi-level drop-water overflow and co-contraction of rivers.The reoxygenation technology,etc.,reconstructs the water environment system structure of the river research section and restores the characteristics of the water environment system of the research river reaches to the characteristics of the water environment system under the condition of no human disturbance.