Tracking And Monitoring Of Water Environmental Factors In Xiangxi Reservoir Bay Based On Automatic Monitoring System Of Water Quality Of Deep-water Profile

With the construction of reservoirs,great changes have taken place in hydrodynamics and water environment of tributary bays.In order to deeply understand the evolution law of water environment and its response mechanism to the external environment,based on the developed automatic monitoring system for water quality in deep water profile,this paper rationally optimizes its function,stability and accuracy to track and monitor the water environmental factors of Xiangxi Reservoir Bay under typical ecological hydrological processes,in order to make clear the driving mechanism of the water environmental factors change of Xiangxi Reservoir Bay.The results are as follows:(1)In the field test,the test results of hardware and software are better,each module can meet the corresponding requirements,and the overall stability of the system is better.Compared with the traditional manual monitoring,the system can achieve hourly tracking monitoring,and it is easier to analyze the evolution law of water quality parameters with time.(2)The study of the diurnal process shows that the obvious diurnal difference of water temperature is mainly related to light and temperature.On March 29 and July 2,2018,the water temperature was in the warming stage from 8:00 to 14:00.The vertical temperature difference of the water body gradually increased,and the water body stratification was obvious.The warming range was the largest from 12:00 to 14:00,and was in the cooling stage from 14:00 to 0:00.The water temperature stratification gradually weakened and disappeared.The warming range was the largest from 16:00 to 18:00,and the diurnal difference of water temperature was obvious between September 25,2018 and November 20,2019.There was no obvious diurnal difference in temperature.Due to the stratification of water body,DO has obvious vertical difference on March 29 and July 2,2018,and the diurnal difference of DO is mainly related to water temperature and phytoplankton.(3)The study of the rainfall process shows that there are two kinds of layered structures in the monitoring site XXB,namely,the normal temperature layering and the isothermal layering.The normal temperature layering mainly occurs at 8:00-20:00,and the homothermal layer mainly appears at 0:00-8:00.Rainfall can not only affect the stratification of water temperature by affecting meteorological conditions(light,temperature,etc.),but also affect the structure of water temperature in the Bay through the density flow generated by run-off.But both have timeliness.After the end of rainfall,the stratification of water temperature gradually forms and tends to be stable after suitable light conditions.Rainfall can inhibit algae growth and reproduction by increasing the depth of mixing layer and reducing the light mixing ratio of water body,but it has stages.After rainfall,the water temperature of water body recovers stratified under 4-5 hours suitable illumination conditions,and phytoplankton begins to grow and increase rapidly,and blooms occur in about 1-2 days.(4)The study on the water storage process shows that the nutrients and water temperature of the water body meet the algae growth conditions during the water storage period,the generation and disappearance of algal blooms are mainly related to the stratification of water bodies..In the early stage of storage,the vertical water temperature tends to be homogeneous and the mixed layer increases,which is not conducive to the growth of algae.In the middle stage of storage,the water temperature of tributary reservoir Bay presents a "step" distribution structure under the action of the bottom backflow water body of the main stream.The mixed layer of the surface water body is 0-10 m,and the light transmittance of the water body decreases,which is not conducive to the growth of algae.Liukuwan Bay has no distinct stratified flow.Influenced by the diurnal difference of solar radiation and temperature,the water body presents weak stratification in daytime,which satisfies the growth conditions of diatom.The diatom blooms erupt in the water body for 2 days.Affected by the decrease of light and temperature,the water body mixes vertically and evenly.The growth of planktonic algae is restrained and the blooms are gradually suppressed.