Contributions of precipitation, irrigation and soil water to evapotranspiration in (semi)‐arid regions

Abstract

Evapotranspiration (ET) is the largest mode of water loss in cultivated (semi)-arid regions. Isolating the fractions of ET contributed by various components of the water budget is critical not only for water resources management, but also for sustainable crop production, food security and social stability. This study quantifies the fractions of ET from precipitation, irrigation and soil water in the North China Plain (NCP) -a major crop production base in China. About 24 consecutive years (288 months) of hydroclimatic data (spanning from January 1985 to December 2008) are used in the study. The data are derived from Global Land Data Assimilation System (GLDAS) input/output products and field-measured data in the region. Error analysis suggests that uncertainties/biases in the data products are low, with good correlations among the data products. In the NCP study area, precipitation is the highest contributor to ET (39.0%, 318.2 mm), followed by soil water (36.3%, 296.2 mm) and then irrigation (24.7%, 201.5 mm). This is respectively the equivalent of 29.7, 43.9 and 66.4% of average soil water, irrigation and precipitation in the region. Precipitation (as the highest contributor) drives the overall trend, amplitude and phase of ET in the study area. While the contribution of precipitation is highest in the wet summer cropping season, the contributions of irrigation and soil water are highest in the relatively dry spring cropping season. It is vital to devise more efficient ET-reduction strategies to ensure sustainability in water use, food security, ecological protection and social stability in the region and beyond.

Performance of AMSR_E soil moisture data assimilation in CLM4.5 model for monitoring hydrologic fluxes at global scale

“…GLDAS product combines satellite data and Land Surface Models (LSM) to estimate global distributions of land surface states such as soil water, runoff and ET (Rodell et al, 2004b;Hogue et al, 2005). GLDAS product has been widely used in many studies, including the initialization of climate/hydrology modeling experiments (e.g., Koster et al, 2004b;Seyyedi et al, 2015;Moiwo and Tao, 2015), land-atmosphere interactions (e.g., Zhang et al, 2008;Liu et al 2014b;Liu et al 2015), and the evaluation and interpretation of new satellite data records or terrestrial water storage (e.g., Syed et al, 2008;Anderson et al 2005;Chen et al 2013;Awange et al 2014;Yang et al 2013;Cheng et al 2015). Though GLDAS is simulated with advanced simulation techniques, it is not bias free and contains some problems.…”

Estimating Evapotranspiration and Its Components in Cotton Fields under Deficit Irrigation Conditions

“…Understanding crop evapotranspiration (ET c ) and its components of soil evaporation (E) and crop transpiration (T) is critical for optimizing agricultural water use [3]. Additionally, the accurate estimation of ET c and its components is vital for efficient water management and irrigation scheduling.…”

Development of an Evapotranspiration Data Assimilation Technique for Streamflow Estimates: A Case Study in a Semi-Arid Region

“…As an important component of the water budget, it is also critical for sustainable crop production, food security and social sustainability [2][3][4]. With the data assimilation method and remotely sensed data, streamflow estimates can be improved a lot [5][6][7][8][9].…”

“…However, most of these studies used remotely sensed soil moisture or snow; little attention has been focused on assimilating observed evapotranspiration (ET) data. In particular, evapotranspiration is the largest mode of water loss in arid and semi-arid regions [2]. Streamflow estimates will benefit a lot from taking into account observed evapotranspiration from remote sensing in these areas.…”