Sanhekou Reservoir’s Water Temperature Structure Characteristics And Study On The Effect Of Stratified Water Intake Measures

The creation of extensive reservoirs will change the water temperature of natural rivers.In particular,the release of cold water from the bottom of stratified reservoirs will cause significant ecological disturbance.Stratified water intake has become one of the important engineering measures to slow down the release of low-temperature water from reservoirs.Water temperature structure characteristics study the effect of reservoir layered water intake,which can provide an important reference for reservoir ecological operation and scheduling.This paper takes the water source reservoir of the Hanjiang to Weihe River Diversion Project—Sanhekou Reservoir as the research object,constructs a three-dimensional water temperature model for the entire reservoir area,calibrates and verifies the model,and simulates the water temperature distribution and distribution of the reservoir under different water diversion scenarios.The discharge water temperature changes,and the water temperature model of the water inlet area in front of the dam was established,and the discharge water temperature simulation and water intake effect evaluation of two stacked beam gate schemes were carried out.The main research results obtained are as follows:(1)Combining the meteorological and water temperature observation data in the study area,the correlation between water temperature and relative humidity,air temperature,wind speed and other meteorological factors are analyzed;the temperature and water temperature fitting curve are used to derive the annual water temperature of Sanhekou Reservoir and dam site Process;Two typical reservoirs were selected,and the water temperature structure conversion time,surface water temperature and bottom water temperature of Sanhekou Reservoir were analyzed by analogy,which provided a reference for the water temperature simulation of the reservoir.(2)According to the reservoir operation mode and water transfer plan,6 working conditions are set,and the difference of the reservoir water temperature distribution and the influence of the discharged water temperature are explored.The reservoir is basically stratified from March to November of the year.The stratification is more significant under high water level conditions.The temperature of the bottom of the reservoir has a relatively small change.The temperature difference within the year is 1.8～2.5℃;compared with high water level,the thickness of low water level thermocline Decrease,the temperature difference of the bottom water temperature is 3.0～6.4℃ during the year.Even with the use of surface water intake measures,the discharge temperature of the reservoir still has the characteristics of a decrease in summer and an increase in winter.The peak delay of the discharge water temperature is basically 30 days,and the water temperature threshold lasts for 1 to 2 months.(3)The effect of layered water intake of the two stacked beam gate schemes of the reservoir is compared and analyzed.Under the three conditions of high water level and high flow rate,high water level medium flow rate and low water level medium flow rate,the scheme with the height of 3m top door leaf of the stacked beam door is better than the water intake effect of 9.8m,and the most significant monthly average water temperature value of the discharged water temperature has been increased 0.9℃.When the surface water temperature gradient is 3～7℃ and the diversion flow is 9.28～37.12m3/s,compared with 9.8m,the water temperature of the 3m stacked girder gate project increases by 0.4～0.9℃ and 0.6～0.8℃,respectively.