Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community

Cooper, David J.; Sanderson, John S.; Stannard, David I.; Groeneveld, David P.

doi:10.1016/j.jhydrol.2005.09.035

Cited by 176 publications

(123 citation statements)

References 43 publications

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“…The upland vegetation that previously occupied riverine upper terraces and grasslands supported small rates of ET (Shafroth et al, 2005;Hultine and Bush, 2011); thus, expansion of phreatophytes into these areas has resulted in an increase in ET losses (Scott et al, 2006b; and thereby has placed a potential strain on groundwater resources. In the case of expansion by Tamarix, groundwater extraction may result in enhancement of ET , contrasting with post-extraction reductions in ET by native, shallow-rooted phreatophytes such as Populus (Cooper et al, 2006;Gazal et al, 2006) and thus representing a shift in the ecohydrology of riparian corridors throughout the semi-arid regions of south-western North America.…”

Section: The Gnangara Moundmentioning

confidence: 99%

“…can be very sensitive to groundwater decline, resulting in reductions of ET, productivity and canopy conductance as a consequence of increases in vapour pressure deficit that are correlated with depth-to-groundwater (Gazal et al, 2006;Kochendorfer et al, 2011). Branch sacrifice, partial crown dieback and mortality commonly occur in Populus following substantial groundwater drawdown (Mahoney and Rood, 1991;Kranjcec et al, 1998;Scott et al, 1999;Rood et al, 2000Rood et al, , 2003Cooper et al, 2003). However, stomatal closure and crown dieback in Populus can prevent total hydraulic failure, and thereby minimise mortality rates, by maintaining favourable xylem water potentials within the remainder of the crown (Amlin and Rood, 2003).…”

Section: The Gnangara Moundmentioning

confidence: 99%

See 1 more Smart Citation

Groundwater-dependent ecosystems: recent insights from satellite and field-based studies

Eamus

Zolfaghar

Villalobos‐Vega

et al. 2015

Hydrol. Earth Syst. Sci.

132

112

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Abstract. Groundwater-dependent ecosystems (GDEs) are at risk globally due to unsustainable levels of groundwater extraction, especially in arid and semi-arid regions. In this review, we examine recent developments in the ecohydrology of GDEs with a focus on three knowledge gaps: (1) how do we locate GDEs, (2) how much water is transpired from shallow aquifers by GDEs and (3) what are the responses of GDEs to excessive groundwater extraction? The answers to these questions will determine water allocations that are required to sustain functioning of GDEs and to guide regulations on groundwater extraction to avoid negative impacts on GDEs.We discuss three methods for identifying GDEs: (1) techniques relying on remotely sensed information; (2) fluctuations in depth-to-groundwater that are associated with diurnal variations in transpiration; and (3) stable isotope analysis of water sources in the transpiration stream.We then discuss several methods for estimating rates of GW use, including direct measurement using sapflux or eddy covariance technologies, estimation of a climate wetness index within a Budyko framework, spatial distribution of evapotranspiration (ET) using remote sensing, groundwater modelling and stable isotopes. Remote sensing methods often rely on direct measurements to calibrate the relationship between vegetation indices and ET. ET from GDEs is also determined using hydrologic models of varying complexity, from the White method to fully coupled, variable saturation models. Combinations of methods are typically employed to obtain clearer insight into the components of groundwater discharge in GDEs, such as the proportional importance of transpiration versus evaporation (e.g. using stable isotopes) or from groundwater versus rainwater sources.Groundwater extraction can have severe consequences for the structure and function of GDEs. In the most extreme cases, phreatophytes experience crown dieback and death following groundwater drawdown. We provide a brief review of two case studies of the impacts of GW extraction and then provide an ecosystem-scale, multiple trait, integrated metric of the impact of differences in groundwater depth on the structure and function of eucalypt forests growing along a natural gradient in depth-to-groundwater. We conclude with a discussion of a depth-to-groundwater threshold in this mesic GDE. Beyond this threshold, significant changes occur in ecosystem structure and function.

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Section: The Gnangara Moundmentioning

confidence: 99%

Section: The Gnangara Moundmentioning

confidence: 99%

Groundwater-dependent ecosystems: recent insights from satellite and field-based studies

Eamus

Zolfaghar

Villalobos‐Vega

et al. 2015

Hydrol. Earth Syst. Sci.

132

112

View full text Add to dashboard Cite

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“…As discussed by Cooper et al (2006) that drought tolerant plant species might survive for decades under conditions of a declining water table with only reduced leaf area, while other plants might experience a significant canopy dieback or death. Further studies should focus on the plant water use strategy under declining groundwater and find the threshold of the water table for maintaining the healthy growth of the shelterbelt to exert the ecological value of wind prevention and sand-fixation.…”

Section: Contributions and Implications Of This Studymentioning

confidence: 99%

Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

Shen

Gao

et al. 2015

Journal of Hydrology

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s u m m a r yPlant water use characteristics and transpiration responses under dry conditions are considered essential for effective and sustainable ecosystem management in arid areas. This study was conducted to evaluate the response of shelterbelt stand transpiration to precipitation, soil drought and groundwater variations in an oasis-desert ecotone in the middle of the Heihe River Basin, China. Sap flow was measured in eight Gansu Poplar trees (Populus Gansuensis) with different diameter at breast height over three consecutive growing seasons (2012)(2013)(2014). The groundwater evapotranspiration via plant use was estimated by the White method with diurnal water table fluctuations. The results showed that precipitation increased the stand transpiration but not statistically significant (paired t-test, p > 0.05). The recharge of soil water by irrigation caused stand transpiration acceleration significantly (t-test, p < 0.05). Stand transpiration and canopy conductance increased by 27% and 31%, respectively, when soil water conditions changed from dry to wet. Canopy conductance decreased logarithmically with vapor pressure deficit, while there was no apparent relationship between canopy conductance and solar radiation. The sensitivity of canopy conductance to vapor pressure deficit decreased under dry soil conditions. Groundwater evapotranspiration (0.6-7.1 mm day À1) was linearly correlated with stand transpiration (1.1-6.5 mm day À1 ) (R 2 = 0.71), and these two variables had similar variability. During the drought period, approximately 80% of total stand transpiration came from groundwater evapotranspiration. This study highlighted the critical role of irrigation and groundwater for shelterbelt, and might provide the basis for the development of water requirement schemes for shelterbelt growth in arid inland river basins.

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“…The ratio of seasonal groundwater evaporation to potential evapotranspiration could be described by an exponential function of water table depth at the YC site (Luo and Sophocleous, 2010). However, the contribution of groundwater to ET gradually reduced with decreasing water table depth (Cooper et al, 2006). This was evident at both the LC and TZ sites.…”

Section: Impacts Of Precipitation Soil and Water Table Depth On Evapmentioning

confidence: 89%

Evaluation of optimal irrigation scheduling and groundwater recharge at representative sites in the North China Plain with SWAP model and field experiments

Feng

Song

2015

Computers and Electronics in Agriculture

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a b s t r a c tThe application of water saving irrigation is essential to alleviate the rapid depletion of groundwater resources in water crisis areas such as the North China Plain (NCP). The integrated effects of climate, soil and groundwater conditions on water balance and crop response need to be further studied. It is imperative to investigate spatial differences of irrigation scheduling and groundwater recharge within the NCP for regional water management. In this study, three representative sites including Luancheng (LC), Tongzhou (TZ) and Yucheng (YC) with different precipitation, soil and water table conditions were selected. The SWAP model was established at each site to compare optimal irrigation scheduling and groundwater recharge of the winter wheat-summer maize double cropping system under different hydrological years. Largest optimal irrigation amount and additional irrigation at the winter-dormancy stage of wheat were required for the TZ site in each hydrological year. The optimal irrigation scheduling was almost same at the three sites for summer maize, except that no irrigation was needed at filling stage in dry year at the YC site. The average annual groundwater recharge under optimal irrigation was in the order of YC (108.4 mm), TZ (63.8 mm) and LC (0.4 mm). Furthermore, the groundwater recharge occurred throughout the double cropping seasons in YC, but it occurred only in summer maize season at the LC and TZ sites. The net irrigation amount of the optimal irrigation scheduling was reduced by 51.2%, 24.9% and 77.2% compared to reference practice at the LC, TZ and YC sites, respectively. The amount of groundwater recharge depended on the local precipitation and irrigation, while water table depth and soil texture mainly influenced the delay time of groundwater recharge relative to the water input events.

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Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community

Cited by 176 publications

References 43 publications

Groundwater-dependent ecosystems: recent insights from satellite and field-based studies

Groundwater-dependent ecosystems: recent insights from satellite and field-based studies

Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

Evaluation of optimal irrigation scheduling and groundwater recharge at representative sites in the North China Plain with SWAP model and field experiments

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