| Dongshan Island has a narrow area,fast runoff into the sea,concentrated precipitation,large evaporation,insufficient fresh water,and small water storage capacity.Therefore,water shortage is the main factor restricting the economic construction and resource development of Dongshan Island.According to Dongshan Island's topography and geomorphology,hydrological characteristics and the current status of water resources development and utilization,this paper uses a SWAT hydrological model to study the runoff process of Dongshan Island and verify it,and this paper establishes a comprehensive utilization system of Island rain and flood integrating assessment,delay and collection,storage,scheduling and utilization.The main conclusions are as follows:(1)The SWAT model of Dongshan Island is constructed based on Arc GIS,and the study area is divided into 34 sub basins and 513 hydrological response units.The SWAT-CUP software is used for parameter calibration analysis.The model is verified by the measured runoff of dongchigang River from 1998 to 2017.The results show that the correlation coefficient(R~2)is 0.83,and the Nash coefficient is 0.80 in the rate period;the correlation coefficient(R~2)is 0.82,and the Nash coefficient is 0.80 in the verification period.According to the applicability evaluation criteria,the SWAT model can be used to simulate the runoff of Dongshan Island.(2)The SWAT model is used to simulate the runoff of typical years with the frequency of10%,25%,50%,75%and 90%,and the annual average runoff of Dongshan Island is 9067million m~3.The hydrological analogy method is used to calculate the annual average runoff of Dongshan Island,which is 9070 million m~3,and the error is within the error range of 0.03%.At the same time,the results are very close to the report of urban and rural water supply integration planning in Dongshan County,Fujian Province,which shows that the simulation results are relatively reliable,and also shows that there is a huge potential for the development and utilization of surface water resources in Dongshan Island,and it is urgent to improve the utilization rate of water resources.(3)Based on the amount of rain and flood resources in Dongshan Island simulated by SWAT model,this paper constructs an efficient utilization technology system of rain and flood resources,which integrates the collection,storage,scheduling and utilization of rain and flood resources.Among them,the research on the delay collection partition of rain and flood resources,and the analysis of the horizontal ditch,low dam for flood detention and rain and flood collection ditch in the hilly area;the urban area in the plain area mainly implements the collection and utilization technologies such as permeable pavement,sunken green space and biological detention pool for residential areas and other buildings,green space and park squares,and urban roads;In the plain area of rural areas,the collection effect of rain and flood delay on roofs,streets and rural ponds is analyzed.The storage of rain and flood resources in Dongshan Island mainly includes the analysis of Hongqi reservoir expansion project,gravel pit rain and flood detention project,and the layout of small rain and flood storage measures,so as to increase the water storage space of Dongshan Island.On the premise of the quality utilization of rain and flood resources,it is proposed that the small surface water reservoirs in Dongshan Island combine with gravel pit rain and flood detention project to establish the rain and flood resources dispatching system with reservoir as the main body.The available water quantity of each surface reservoir is comprehensively analyzed.(4)Based on the comprehensive utilization system of island rain and flood resources,the effect of collection and utilization of rain and flood resources in Dongshan Island is analyzed.About 23.57 million m~3 of rain and flood resources can be collected in hilly small watershed to supply domestic water;13.39 million m~3of rain and flood resources can be collected in urban area through green roof and permeable brick laying measures,which can be used for industrial water;1.255 million m~3 of rain and flood resources can be collected in plain rural area by decentralized green roof for rural domestic water;18.6 million m~3 of agricultural irrigation water can be collected by adding well and pond dam.(5)The annual runoff of Dongshan Island in the normal water year(P=50%)is 90.6billion m~3,the comprehensive calculation of various water consumption amounts to 56.815million m~3,and the utilization rate of rain and flood resources is increased from 20%to 62%.Meanwhile,the water storage space of Dongshan Island can be increased by 10.67 million m~3to improve the capacity of water storage resources.According to the principle of joint regulation and the calculation method of regulation,the water quantity of each sub reservoir of reservoir group I can be transferred into Hongqi reservoir It is 2.934 million m~3.Each sub reservoir of reservoir group II can transfer 1.002 million m~3of water into the sand and stone pit of Wulong Road,and each sub reservoir of reservoir group III can transfer 825000 m~3into the sand and stone pit of dalukou,which greatly enhances the ability of regulating water resources and ensuring water safety of the whole island.Therefore,the comprehensive utilization system of rain and flood resources in Dongshan Island should be constructed,It can provide scientific and technological support for the comprehensive development and utilization of rain and flood resources in Dongshan Island,help to make good use of local rainwater and flood resources,enhance the regulation ability of water resources,and alleviate the excessive dependence on external water transfer in Dongshan Island. |
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