A worldwide evaluation of basin-scale evapotranspiration estimates against the water balance method

Liu, Wenbin; Wang, Lei; Zhou, Jing; Li, Yanzhong; Sun, Fubao; Fu, Guobin; Li, Xiuping; Sang, Yan‐Fang

doi:10.1016/j.jhydrol.2016.04.006

Cited by 194 publications

(175 citation statements)

References 72 publications

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“…While these studies generally agree on positive trends since the 1980s, they differ in the magnitude of the estimated trends (Dong and Dai, 2017). It has been noted, however, that the results of such models need to be treated with care as they are sometimes inconsistent with trends from the water balance, particularly for wet basins (Zhang et al, 2012;Liu et al, 2016).…”

Section: Introductionmentioning

confidence: 95%

Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

Duethmann¹,

Blöschl²

2018

Preprint

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Abstract. Global warming has increased regional evapotranspiration in many parts of the world in the last decades, but the drivers of these increases are widely debated. Part of the difficulty lies in the scarcity of high-quality long term data on evapotranspiration.In this paper, we analyze changes in catchment evapotranspiration estimated from the water balances of 156 catchments in Austria over the period 1977-2014 and attribute them to changes in atmospheric demand and available 10 energy, vegetation, and soil moisture as possible drivers. Trend analyses suggest that evapotranspiration has significantly increased in 60 % of the catchments (p≤0.05) with an average increase of 29 ± 14 mm y . Estimates of reference evaporation accounting for changes in stomata resistance due to changes in NDVI indicate that the increase in vegetation activity has led to a similar increase in reference evaporation as changes in the climate parameters. A regression between trends in evapotranspiration and precipitation, as a proxy of soil moisture, yields a sensitivity of 0.30 ± 0.04 mm y −2 increase in evapotranspiration to 1 mm y −2 20 increase in precipitation. A synthesis of the data analyses suggests that 38 ± 13 % of the observed increase in catchment evapotranspiration can be directly attributed to increased atmospheric demand and available energy, 30 ± 12 % to increased vegetation activity, and 32 ± 5 % to increased soil moisture due to increases in precipitation. IntroductionEvapotranspiration (E) is an important process in the water, energy, and carbon cycles and directly controls agricultural 25 productivity and water availability for human purposes. Global warming has increased regional E in many parts of the world in the last decades (Huntington, 2006). However, due to the difficulty of measuring E, especially at large spatial scales, the drivers of changing E are still debated.Decadal changes in catchment E may be inferred from the catchment water balance, as storage changes are usually small over decadal scales. Surprisingly few studies have investigated trends in water balance based evapotranspiration (E wb , despite increases in air temperature (Peterson et al., 1995;Roderick et al., 2009;McVicar et al., 2012). In some instances, this decrease in E pan has been explained by decreases in net radiation and/or wind speed (Roderick and Farquhar, 20 2002;Roderick et al., 2007). In other instances, decreasing E pan has been interpreted as a consequence of increasing actual evaporation (Brutsaert and Parlange, 1998;Brutsaert, 2013). In Europe, most studies found increasing trends of E pan (e.g. Ireland (1963Ireland ( -2005 (Stanhill and Möller, 2008), England (1957-2004 and 1986 (Stanhill and Möller, 2008;Clark, 2013), Greece (1983Greece ( -1999 (Papaioannou et al., 2011), and the Czech Republic (Trnka et al., 2015)). In this paper, we use the term atmospheric conditions to summarize the drivers available energy and atmospheric demand. 3 CO 2 concentration and nitrogen deposition, Mao et al. (2015) found that...

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Section: Introductionmentioning

confidence: 95%

Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

Duethmann¹,

Blöschl²

2018

Preprint

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“…It has been demonstrated that S cannot be neglected in water balance calculation over monthly and annual timescales due to snow cover change and anthropogenic interferences (e.g. reservoir operation, agricultural water withdrawal; Liu et al, 2016a). For the period 2002-2011, we calculated basin-wide ET (ET wb ) directly using the GRACE-derived S in Eq.…”

Section: Water Balance-based Et Estimationmentioning

confidence: 99%

“…The monthly ET biased series (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) can then be biascorrected through the inverse function (F −1 ) of the gamma cumulative distribution function (CDF, F) of ET wb by matching the cumulative probabilities between two CDFs as follows (Liu et al, 2016a):…”

Section: Water Balance-based Et Estimationmentioning

confidence: 99%

“…A few attempts have been made to validate multiple datasets for certain water budget components and to explore their possible hydrological implications. For example, and Liu et al (2016a) evaluated multiple ET estimates against the water balance method on annual and monthly timescales. Bai et al (2016) assessed streamflow simulations of GLDAS LSMs in five major rivers over the TP based on the discharge observations.…”

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confidence: 99%

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Investigating water budget dynamics in 18 river basins across the Tibetan Plateau through multiple datasets

Liu

Sun

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. The dynamics of basin-scale water budgets over the Tibetan Plateau (TP) are not well understood nowadays due to the lack of in situ hydro-climatic observations. In this study, we investigate the seasonal cycles and trends of water budget components (e.g. precipitation P , evapotranspiration ET and runoff Q) in 18 TP river basins during the period 1982-2011 through the use of multi-source datasets (e.g. in situ observations, satellite retrievals, reanalysis outputs and land surface model simulations). A water balancebased two-step procedure, which considers the changes in basin-scale water storage on the annual scale, is also adopted to calculate actual ET. The results indicated that precipitation (mainly snowfall from mid-autumn to next spring), which are mainly concentrated during June-October (varied among different monsoons-impacted basins), was the major contributor to the runoff in TP basins. The P , ET and Q were found to marginally increase in most TP basins during the past 30 years except for the upper Yellow River basin and some sub-basins of Yalong River, which were mainly affected by the weakening east Asian monsoon. Moreover, the aridity index (PET/P ) and runoff coefficient (Q/P ) decreased slightly in most basins, which were in agreement with the warming and moistening climate in the Tibetan Plateau. The results obtained demonstrated the usefulness of integrating multi-source datasets to hydrological applications in the data-sparse regions. More generally, such an approach might offer helpful insights into understanding the water and energy budgets and sustainability of water resource management practices of data-sparse regions in a changing environment.

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“…Net primary productivity (NPP), a key element in the carbon cycle, not only reflects the productive capacity of the plant community but also is the main factor that determines whether an ecosystem is a carbon source or sink [13,14]. Evapotranspiration (ET), an important part of the water cycle in an ecosystem, is the only component that links the heat balance and water balance via interactions between the land surface and the atmosphere [15,16]. Water use efficiency (WUE), an important variable linking the vegetation-based carbon cycle and water cycle in an ecosystem, defines how efficiently plants use water to produce biomass [17,18].…”

Section: Introductionmentioning

confidence: 99%

Ecological Effects of Grazing in the Northern Tianshan Mountains

Huang

Luo

et al. 2017

Water

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Abstract:Identifying the effects of grazing is critical for the conservation, protection and sustainable use of arid grassland ecosystems. However, research regarding the ecological effects of grazing along mountainous elevation gradients is limited in arid areas, particularly at the regional scale. Using the Biome-BGC grazing model, we explored the effects of grazing on grassland net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) from 1979 to 2012 along an elevation gradient in the northern Tianshan Mountains. The NPP, ET and WUE values were generally lower under the grazing scenario than under the ungrazed scenario; the differences between the grazing and ungrazed scenarios showed increasing trends over time; and distinct spatial heterogeneity in these differences was observed. Distinct decreases in NPP and WUE under the grazing scenario mainly occurred in regions with high livestock consumption. The decrease in ET was greater in mountainous areas with high grazing intensity due to decreased transpiration and increased surface runoff. This study contributes to a better understanding of the ecological effects of grazing along an elevation gradient in the northern Tianshan Mountains and provides data to support the scientific management of grassland ecosystems.

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A worldwide evaluation of basin-scale evapotranspiration estimates against the water balance method

Cited by 194 publications

References 72 publications

Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

Investigating water budget dynamics in 18 river basins across the Tibetan Plateau through multiple datasets

Ecological Effects of Grazing in the Northern Tianshan Mountains

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