Agricultural Drought Model And Application

Agricultural drought model was built by way of modleling and inquisition and experiment in china.It has been applied to evaluating agricultural drought, monitoring agricultural drought and making agricultural drought strategy.A long history has been experienced to research into the geographical aridity and humidity by use of various indices. The ratio of precipitation (P) to potential evaporation(E) can be defined as drought index.But it can't be used to describe agricultural drought.Agricultural drought on farmland or basin,which restricted by climate, geo logy,hydrography, soil moisture,plants, cultivation and water allocation etc.,is a complicated system.The strcuture of water balance system was analysed.The formulations was given in details The agricultural drought index can be defined as I=1-Ea/EWhere:Ea is the actural evapotranspiration.A calculation formula of evaporans piration, in which many factors were taken into account, was set up as follow: ETas=Min (Ss or ETm-Pe) ETas= [ETm-Pe-ETas] [Su/Awc]~m ETa=ETas+ETau+PeAgricultoral drought model contains 5 models:agricultural drought index model, water circulation model, water requirement model, forest water balance modlel and crop productive potentialities model.Agricultral drought model has been tested by several methods: water circulation model by water balance method: water circulation model by water balance method, agricultural drought index by inquisition and crop productive potentialties model by biomassay.The regions inspected contain Liaohe basin, Hai luanhe basin, Huai he basin.Huang he basin and chang jing basin. The results showed that agricullura drought model is compatible and precision.Agricultural drought model can be used to evaluate and monitor agricultural drought, make strategies of agricultural drought and etimate crop yield.