Abstract

Budyko's framework has been widely used to study basin-scale water balance. In this study, we focus on the extended application of Fu's equation (one formulation of the Budyko-type curves) to 371 large irrigation districts in China over a period of 2010–2017. Water balance method was used to estimate actual evapotranspiration (ET) in the irrigated areas. Considering the contribution of shallow groundwater to ET, the water availability in the Budyko framework defined as equivalent precipitation (Pe) for irrigation areas is the sum of irrigation water (I), precipitation (P) and groundwater evaporation (ETgw). Results showed that the relationships between evapotranspiration (ET), water availability (Pe) and energy supply (ET0) can be accurately described by the Budyko's curves. The Fu's equation performed better in humid and semi-humid regions than arid and semi-arid regions. The comparison between δET/δPe and δET/δET0 confirmed the relative effect of water availability and energy supply on ET according to the variation of climatic conditions. The optimal values of Budyko parameter ω for each irrigation district was obtained with multi-annual data using least square method. Normalized Difference Vegetation Index (NDVI) and soil property (denoted by the proportion of clay and sand) were selected to develop empirical equation for parameter ω using multiple linear regression analysis method. This study showed that the Budyko framework can be extended to irrigation areas and provide useful information on evapotranspiration to assist in water management in irrigation areas.

Highlights

  • Quantifying the partitioning of precipitation (P) at land surface into evapotranspiration (ET) and runoff (R) is of great importance in hydrology and water resources management.Serving as an effective tool to assess the partitioning, the Budyko framework proposed by Budyko (1974) has been widely used in global and regional scales within the past several decades (Caracciolo et al, 2018; Gerrits et al, 2009; Moussa and Lhomme, 2016; Roderick and Farquhar, 2011; Troch et al, 2013; Wang and Hejazi, 2011)

  • The original Budyko formulation without parameters was assumed to be used in large basins at time scale significantly longer than 1 year (Gentine et al, 2012; Roderick and Farquhar, 2011), in which the evapotranspiration is dependent on the balance between energy supply and water availability

  • For long-term water balance in large natural catchments, evapotranspiration can be regarded as the partitioning of precipitation which is serving as water availability in Budyko formulations (ET = P − R) while water storage is assumed to be negligible (Donohue et al, 2010; Hobbins et al, 2001; Rodell, 2004; Xue et al, 2013)

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Summary

Introduction

Quantifying the partitioning of precipitation (P) at land surface into evapotranspiration (ET) and runoff (R) is of great importance in hydrology and water resources management.Serving as an effective tool to assess the partitioning, the Budyko framework proposed by Budyko (1974) has been widely used in global and regional scales within the past several decades (Caracciolo et al, 2018; Gerrits et al, 2009; Moussa and Lhomme, 2016; Roderick and Farquhar, 2011; Troch et al, 2013; Wang and Hejazi, 2011). Quantifying the partitioning of precipitation (P) at land surface into evapotranspiration (ET) and runoff (R) is of great importance in hydrology and water resources management. The original Budyko formulation without parameters was assumed to be used in large basins at time scale significantly longer than 1 year (Gentine et al, 2012; Roderick and Farquhar, 2011), in which the evapotranspiration is dependent on the balance between energy supply and water availability. With the emergent deviation of measured data from the Budyko curve, more attention has been recently focused on the influence of catchment features or scales analysis on ET (Donohue et al, 2007). In this context, many studies subsequently derived.

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