Evaluation Of Effectiveness Of Soil Moisture In Shiyang River Basin Farmland And Its Dynamic Simulation

Soil moisture dynamic variation, simulation and evaluation of the effectiveness of soilmoisture and the simulation of water movement has long been a hot topic in arid andsemi-arid regions, it is the theoretical basis for forecasting and scientific management ofwater-saving irrigation. In this paper, we studied the dynamic variation of soil moisture inspring wheat, spring corn and bare farmland, lacated in Shiyang River Basin, Gansu Wuwei.And we evaluated the effectiveness of the soil moisture. It build a core of farmland soil watermovement hierarchical model, the model was validated. Obtain the following main results:(1)In Shiyang River Basin， bare land, spring wheat and spring corn farmland’s soilmoisture is impacted by precipitation (irrigation), evapotranspiration and soil moisturemigration and other reasons, so they changed quickly. Bare land and spring wheat, two typesof spring maize crop farmland compared to the dramatic changes in soil moisture lesser extent,deep (80-100cm) soil moisture remained stable. The crops covered farmland deep (80-100cm)soil moisture is still a large degree of change, affected crop root water uptake, there are cropsfarmland soil moisture changes include more severe soil deep. Evapotranspiration influencedby soil moisture content, soil moisture content at a low level for a long time will lead to asubstantial reduction in evapotranspiration.(2)Under the conditions of the local irrigation system, basic water spring wheat crop rootzone for the entire growth period "effective medium", on spring wheat growth beneficial;moisture in the root zone of spring maize crop in the period from birth "easy effect" to"difficult after effect ", and with soil depth, soil validity of the" easy effect "to" hard effect "oftime in order to push that growth period in the spring corn, deep soil water will be less andless effective increasingly difficult to crop use.(3)Build a hierarchical model to assess soil moisture effects on crop transpirationevaporation. And application of the model soil moisture in spring wheat and spring maizecrop in different soil evaporation and transpiration of impact were assessed. The resultsshowed that: For spring wheat, surface and shallow soil (0-30cm) of water status greatestimpact on crop growth; for maize, shallow and middle soil (10cm-80cm) of water statusmaximum impact on growth (4) Construction of the spring wheat heading-maturity stage of farmland soil moisturelayered motion model, and verified by simulation; the dynamic changes of soil water30-80cmis high precision and the upper and deeper soil moisture is poor precision.