The Storage Optimization Calculation Of The Urban Rainwater Harvesting System Based On Simulation Of Supply And Demand Of Water

Since the21st century, our country rapidly entered the urbanization development stage, thegrowth of city water supply caused by urbanization accelerate process. Subsequently the problemwe need to face up to and to seek the breakthrough in development plans as a country which is inshort of water supply. This article is on classification of domestic and foreign literatures, to dorelated research from two aspects: prediction of water demand and rainwater harvesting systems,construct simulation model to the optimization calculation of the volume of the water tank urbanrainwater harvesting system.For the forecast of urban water demand, through the method of classification and prediction,we can see the social economy, ecological environment and water resources cycle system as anorganic whole to analysis the economic aggregate and structure, water consumption quota for theinfluence factors of water supply. According to the trend of the factors affecting water change,the growth trend of water consumption and various part water supply of the mechanism of waterdemand, we choose different forecasting methods to forecast and in respect of the practicalproblems in prediction of water to be treated to provide information for decision makers.This thesis is on the analysis the design of residential landscape and rainwater collection,rainwater drainage and utilization form, the use of rainwater, irrigation form of green land, thewater permeability of hard pavement, etc. The facilities of the rainwater collection and utilizationin residential quarters are divided into three types: water storage facilities, infiltration facilitiesand filtration facilities to be explored in this thesis.The rainwater harvesting system (RHS) can effectively supply the reuse water, but theuneven distribution of the rainfall has greatly affected its working efficiency. Natural rainfall is arandom process, with uncertainty, so it is necessary to study the relationship among rainfallpossibility, design storage capacity, RHS supply shortage. The relationship between RHS storage capacity and shortage rate of water supply wascreated in this paper. Taking Pinghu city of Zhejiang Province as the research object, thefeasibility of using the system simulation model to research the feasibility of storing rainwaterinstead of flushing toilet water is studied. Based on the simulation results of historical rainfallrecords, the relationship between storage capacity and water shortage is established. According tothe calculation, the annual rainfall of50years (1959-2008) of Pinghu City,2215mm,55%ofrainfall was concentrated in June to September. Shortage rate occurred by each specific designstorage capacity (1,5,10,20,50,60,100,150cubic meters) showed normal distribution and allthe configuration distribution consistent with fitting should be test. The change of shortage rateincreases with the increase of storage size. When design storage size exceeds90, the effect ofreducing the shortage rate is reduced and tended to0by increasing the design storage. This layerof the ceiling shows that the maximum available water is restricted by volume of the localhydrological, can set upper limit in the RHS to improve the water supply. EP curve describe thecontinuous relationship between the storage capacity and shortage rate and the application of therelationship between the storage equipment and shortage rate are discussed. A single or limitedprobability curve can only describe the features for the shortage of RHS in some special designof storage devices, the probability of distribution curve of the relationship between the storagecapacity and the shortage of rate and transcendental probability curve is presented in this paper.The results of the research can be used as the reference for the storage capacity of RHS.