Dataset used for the application of Budyko in irrigation areas
In this study, we evaluated the potential application of the Budyko hypothesis in agricultural irrigation areas. 8-year observed (2010-2017) data about 371 large irrigation districts including annual irrigation water, specified location, total irrigated area and irrigation water use efficiency were collected and provided by China Irrigation and Drainage Development Centre. Daily precipitation and monthly meteorological data including wind speed, air temperature, and relative humidity from weather stations on or around the selected irrigation districts covering the same period were downloaded from China meteorological data network (http://data.cma.cn/). The values of NDVI (Normalized Difference Vegetation Index) were extracted from MOD13A1 products with spatial-temporal resolution of 500 m and 16 d, which were available to download from the NASA Data Centre at https://reverb.echo.nasa. gov. The Digital Elevation Model (DEM) data with a spatial resolution of 1 km were downloaded from http://srtm.csi.cgiar.org/. The distribution map of soil texture denoting the proportion of sand and clay was provided by Data Centre for Resources and Environmental Sciences, Chinese Academy of Sciences (RESDC) (http://www.resdc.cn). The actual evapotranspiration was estimated as the sum of net irrigation water and effective precipitation by water balance equation. Irrigation activities have changed the natural hydrological processes and influence the allocation of water availability. By incorporating both irrigation water and precipitation in water availability, Budyko framework performed well in irrigation areas. In arid and semi-arid areas, 10% increase in irrigation water brings 1.58% to 5.29% increase in evapotranspiration, and 10% increase in precipitation brings 0.97% to 4.25% increase. For humid and semi-humid areas, the variation of evapotranspiration is mainly caused by energy supply and a 10% increase in potential evaporation brings 6.79% to 8.61% increase in evapotranspiration. Using the 8-year data, the optimal values of Budyko parameter ω was obtained by least square method. The values of ω in humid and semi-humid areas were generally large than those in arid and semi-arid areas. An empirical equation was developed to describe the obvious relationship between ω and NDVI and soil property. The equation performed well in reproducing parameter ω given its simplicity and easy accessibility to input factors.