Movement Of Soil Salts In Qingtongxia Irrigation Area

Qingtongxia irrigated area, located in the Hetao area of Ningxia Hui Autonomous Region, has had more than 2000 years pumping water from Yellow river irrigating because there is an arid region, evaporating strongly, the groundwater depth of burial being shallow, especially in Yinbei Region, the perpendicular motion of groundwater being fairly acute, and the salt content of groundwater being detained in soil, which caused the soil salinization. The irrigated area has become Ningxia agriculture and the industrial economy center, but the problem of land salinization is still not solved. Along with the Western Developments and the implementation of saving modification works of irrigation area, and the land salinization has become the largest obstacle influencing the development of irrigated area economy. In this paper irrigated area water salt balance and the trends change is studied, the cause of formation and the trendence of saline-alkali land is analysized; the foundmental theory for the administration of saline-alkali land is provided.Beginning with the analyse of present situation and cause of formation of saline-alkali land, the irrigated area overall water salt trends are analysed, and the irrigated area saline-alkali land and the groundwater level and distribution law of groundwater degree of mineralization are expounded, the trendence of irrigated area saline-alkali land is put forward. Then water salt balance model is estanbished according to the relationship of irrigating and drainage. Regarding the irrigated area as a balance area, by analysis of mineralization degree of water pumping from the Yellow River and drained off water from irrigated area, the change of the draining off water ion is forcasted in water reducing condition. Use the water salt dynamic model principle of irrigated area, the present situation (in 1998 2000) and future year overall water salt balance is calculated. The water salt trends in irrigated area is analysed and the standard of drained off water control is put forward.