Salt and water balance analysis after adopting controlled drainage in Yinnan Irrigation District, Ningxia, China

Abstract According to data collected from a field experiment of controlled drainage in Yinnan Irrigation District, this paper analyses the amount of drainage water and variation of salt and water balance. Compared with traditional drainage, it is found that the volume of drainage water is obviously reduced by controlled drainage. The groundwater table in the controlled drainage areas is 1.8 cm higher than that in the traditional drainage areas. If drainage velocity is used to substitute for the volume of drainage water, the total volume of drainage water drained from controlled drainage areas is on average 50% less than that from traditional drainage areas. At the same time, the volume of underground drainage water decreases by 46%. By analysing the balance between salt and water in the controlled drainage areas, the introduced amount of salt is less than the discharged amount of salt, so salt and water are still kept in good status. Copyright © 2008 John Wiley & Sons, Ltd.