Study On Optimization Of Wells Space Layout In Well-canal Combined Irrigated Area Based On GIS

The rational distribution of motor-pumped wells was important to the reasonable exploitation and utilization of groundwater resources and national food security.For rational use of surface water and groundwater resources,improve the ecological environment of irrigation area,provide the basis for the realization of the most stringent water management.Taking people's victory canal irrigation district as the research area,using Arc GIS analyzes the people's victory canal irrigation district groundwater utilization status,using MATLAB optimization model,with the goal of maximizing the net irrigation benefit,proposed the establishment of surface water and groundwater joint scheduling and crop structure optimization model coupled with MODFLOW model,established a fully irrigated three dimensional flow numerical simulation model.Based on the characteristics of water supply for the people's victory canal irrigation district,set up eight different programs to simulate,forecast the water level of the programs running in five years,analysis the reasonable groundwater resources development programs and the optimal layout of the wells.The results provide technical support for the most stringent water resources management in irrigation areas.The main results were as follows:(1)The temporal and spatial variation trend of groundwater and its influencing factors were analyzed.In recent years,with the development of economy and society,water shortages increasingly serious in people victory canal irrigation district.In order to meet crop irrigation water demand,exploitation of groundwater was growing,the groundwater depth is increasing in the past 35 years.Rainfall,yellow river water and groundwater exploitation are the main influencing factors affecting the change of groundwater depth.Under the influence of environmental change,the current rainfall and yellow river water is decreasing,while the exploitation of groundwater in the irrigation area is increasing.The well-canal irrigation proportion is too large,and the groundwater has been over-exploited.In some areas,the underground water funnel has been formed.To this end we have to take measures to change the over-exploitation of groundwater in irrigation areas to prevent further deterioration of the ecological environment of irrigation.(2)Optimize the allocation of water resources and crop acreage in irrigation area.In order to change the status of water environment deterioration,using MATLAB programming to optimize the allocation of yellow river water and groundwater resources and crop acreage.The simulation results show that the use of scheme of optimization of water and crop planting area that can enhance the water level,especially midstream 3 District and downstream 6 District,landing funnel range decreases,and improve irrigation area of groundwater funnel situation.Through the optimization algorithm adjusts the upstream zone 1,the middle reaches 2,District 4,District 5 still have potential for development,for a total increase of wheat and corn acreage is 43710.9hm~2,midstream and downstream 6 District 3 area needs to be compressed wheat and corn It acreage 1047.39hm~2.1 upstream and midstream area 3 Total area required compression rice planting area 14952.02hm~2,can significantly improve the irrigation area of groundwater funnel status quo and the trend of the underground water level serious decline.(3)Establishment of numerical simulation model of groundwater in combined irrigation area.According to the observed data of irrigation area for many years with the ArcGIS statistical calculation,combining MODFLOW established well drainage and irrigation area of groundwater dynamic simulation model,simulation compared with observation point the original water level,water level at various points evenly distributed near the related line on both sides of the 1:1,all the calculated water level compared with the original water level of observation points,the errors are within the acceptable range,showed that the identified hydrogeological parameters can objectively reflect the practical geological conceptual model of irrigation area,by using the MODFLOW model can simulate the people's victory canal irrigation district of groundwater spatial change.(4)Simulation of groundwater change in in combined irrigation area under eight scenarios.In this paper,using the groundwater simulation model to simulate the irrigation area of groundwater forecast for many years,results showed that the reduction of irrigated groundwater extraction,has obvious effect of underground water level,with the increase of groundwater excavation cut,full irrigation area of underground water level is also rising,10 per cent reduction of groundwater extraction in flat water years,groundwater irrigation area can maintain homeostasis.Estimation Results showed that the well-canal irrigation proportion was adjusted to 1/0.78,the number of planned wells Irrigation adjustment from the original 20,261 to 14,315,groundwater recharge and can basically achieve the balance,significantly improving irrigation district groundwater level serious decline.