Analysis Of Drying Or Wetting Changes Based On The Balance Of Land Water Supply And Demand In Inland River Region Of Northwest China

The Inland River Area of China(IRAC)with a typical continental climate,and the main water resources include mountain precipitation and snowmelt in the whole region,is the most water-stressed region in the world,and faces with increasingly severe ecological degradation risk and water shortage issue under global climate warming.Previous studies indicated that the climate of IRAC have changed from warm-dry to warm-wet,because both precipitation(P)and air temperature have increased.However,the analysis in this study,which is based the model output of land surface model NOAH,considers the effects of climate change on hydrologic cycle rather than simply on climate conditions,the main results are as follow:(1)The data evaluation results of Global land Data Assimilation System Version 2 NOAH model showed that the driven data of the model had a good consistency with the measured site data and the China Meteorological Forcing Dataset,and the ET in the output results had a good consistency with the ET in the GLEAM data-set.The GLDAS2.0/NOAH model(based on advanced land surface modeling and data assimilation technology)can provide accurate input variables(surface water-energy)for Standardized Moisture Anomaly Index(SZI)calculation.(2)In this study,SZI(a multi-time-scale drought index based on water supply and demand balance to measure the degree of drought)was used to identify regions in the condition of drought or humidity;Compared with Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI),SZI's change is more consistent with residual water/energy ratio,evapotranspiration deficit and historical drought record.(3)Based on SZI drought area change tendency as a result,found in the northwest inland areas ahead of the 1970 land surface there is a continuous drying trend,and after 1970 years,from the annual drought area of change over the past 40 years,land surface condition in the study area has been in a stable condition,the continental river region water supply(P)with a significantly increase of the climate warming is balanced by the increase in water demand;The results of spatial distribution of interannual drought variation trend from January to December,indicates that from 1971 to 2010,the wetting state of land surface in this region is mainly in autumn and winter,while land surface condition in growing season presents a trend of drying.