Numerical Simulation Of High Sandy Water Ecological Replenishment In Artificial Shallow Lake

Nowadays most of city artificial lake facing problems of insufficient supply ofwater and deterioration of water quality,“water diversion project” to a great extent onimproving lake water eco-systems, thus protecting the lake’s various functions.However, poor rainfall in the north, water system is not developed, so water bodiesact as water source are seldom. Yellow River as the large rivers of the north, are ableto provide an adequate amount of water which contains large amounts of suspendedsediment. What’s worse, water quality of seriously polluted in recent years led to therelatively poor, the Yellow River supplies will have a certain impact on the lake. Thisarticle relies on the "Yellow River Diversion Project" of Dongchang Lake, usingMIKE21model software to establish mathematical model from both hydrodynamicand water quality, to discuss the effects on the Dongchang Lake after the Yellow Riverreplenishment, with a view to provide theoretical support of scientific management tolake and Yellow River water diversion project. Field sampling and laboratory testswere conducted to get meteorological, hydrological, hydrodynamic, water quality andother relevant data of the Dongchang Lake during water replenishment process,thereby establishing hydrodynamic-sediment, hydrodynamic-quality, hydrodynamic-quality-sediment coupled model and setting up a different program for numericalsimulations of hydrodynamic and water quality.Driving characteristics and formation mechanism of Dongchang Lake loop isascertained by hydrodynamic simulation of the Lake: The results showed thatwind-driven flow is the main form of water cycle in the Dongchang Lake. Lakevelocity was decided by wind speed, and lake circulation is decided by wind direction.The longer of lake shore was impacted by wind, the more the water circulation was formed. During the water supply period, water flow condition has been temporarilychanged by water supply and suspended sediment. Although lake water level don’tdirectly impacted the water circulation, it will impact the water circulation under windand water supply cooperation. Sensitivity analysis indicated that wind is the mostsignificant diver factor for water circulation in the Dongchang Lake. Therefore, underthe low water level and strong wind, intermediate water supply can more obviouslyimprove water cycle in the Dongchang Lake.The results of water quality simulation of the Dongchang Lake showed thatAlgae, nutrients and other substances are contained in the water of the Yellow River,and their concentrations are higher than the Dongchang Lake. In addition, a largenumber of suspended sediment has been contained by the Yellow River water, if theYellow River’s water is used as supply water, pollution will be produced. There areadvantages and disadvantages, because the presence of suspended sediment.Suspended sediment as one kinds of pollutants affects the lakes transparency andchroma, so the photosynthesis of plants are affected. Deposition of suspendedsediment lead to the bottom of the lake rises is elevated and the river is blocked. Onthe contrary, precisely because of the presence of suspended sediment, replenishmentwater is purified, and lake pollution is reduced. Distribution of chlorophyll a anddissolved oxygen are less affected by the suspended sediments, however, nitrogen,phosphorus and other nutrients are more affected.