| Radial well has some attractive features for certain locations. Massive discharge, having a long utilizable life, great ability for control groundwater, high speed for de-groundwater level, controlling large area, convenient management, easy repair, less land occupation are factors in favor of a radial well. It is suitable a type of well for exploiting groundwater, carrying out canal-well conjunctive irrigation, combining irrigation and drainage, achieving jointing surface water and groundwater, comprehensive controlling of drought, water-logging, salinization and alkalization. In Yinbei irrigation district, the aquifer is fine sand loam or fine sand within 50 m in depths and the thickness of aquifer normally is 20~40m. Because of irrigation by yellow river, ground water in this part is fresh water or slightly salty water. In this article, canal-well conjunctive irrigation using radial well technique is studied in the situation of Yinbei irrigation district.The irrigation and drainage model in Yinbei irrigation district is combined groundwater and surface water irrigation. Groundwater is not only for irrigation but also for drainage. The main irrigation is surface irrigation from yellow river and groundwater irrigation is assistance. The ratio of surface water and groundwater is 7:3. The irrigation model is as following. In spring irrigation time, from the last ten-day of a April to the first ten days of May, farmers irrigate the land for sowing and also for desalinization by using yellow river, but in some water shortage areas groundwater is adopted. In summer time irrigation, from the middle ten days of May to the last ten-day of a Jun, water shortage is relative severity, so it is better to utilize the groundwater for irrigation and decrease the water level for groundwater reservoir. In some area, surface water is available, therefore it can uses combined groundwater and surface water irrigation. In early autumn irrigation, from July to September, yellow river water is abundant in this period, so farmers can use surface water to irrigate the land and recharge the aquifer. In late autumn irrigation, from the first ten day of October to the middle ten day of November, the method of combined groundwater and surface water irrigation is adopted and the surface water is main resource with the ratio of surface to ground water 2:1 ~ 3:1. Using groundwater may controlgroundwater level, and then soil salinity in springtime of next year dose not happed.For calculating of radial well discharge, "equivalent big diameter well" can be adopted. The radial well discharge in Yinbei irrigation district is about 250~350m3/h and can control 600 Mu (40 hectare). It is suggested that both surface irrigation and ground irrigation utilize the same irrigation canal. Because radial well can control large farmland, it is better to layout the radial well near the lateral canal or sub-main canal in Yinbei irrigation district so that the flow of surface and groundwater can mix. The number and space of radial well can be determined by using the single well control area method.In Yinbei irrigation district, normally the design depth of radial well is 30~35m with reinforce concrete collector pipe 2.5-3.5m in diameter. The hole is made by reverse circulation drill machine and the collector pipe is installed into the hole by the method called "buoyancy install". The horizontal colander pipe of each radial well is divided into 6-8 layer with 6-8 pipes for each layer and the best location of horizontal colander pipe is at the bottom of aquifer. If the water pressure in aquifer is higher than 10m, the colander pipe is jacked into the aquifer by hydraulic jack and the colander pipe has two layer, steel pipe with hole outside and plastic ripple pipe with nylon filter inside. If the water pressure in aquifer is less than 10m, the colander pipe is drilled into the aquifer by the "steel sleeve pipe drilling method" and the colander pipe is plastic ripple pipe with nylon filter.The drill machine for the horizontal colander pipe is not s...
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