Large-scale sensitivities of groundwater and surface water to groundwater withdrawal
<p>Increasing population, economic growth and changes in diet have dramatically increased the demand for food and water over the last decades. To meet increasing demands, irrigated agriculture has expanded into semi-arid areas with limited precipitation and surface water availability. This has...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/464ec94ee4224c57ac225e789b8840a9 |
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| Sumario: | <p>Increasing population, economic growth and changes in diet have dramatically
increased the demand for food and water over the last decades. To meet
increasing demands, irrigated agriculture has expanded into semi-arid areas
with limited precipitation and surface water availability. This has greatly
intensified the dependence of irrigated crops on groundwater withdrawal and
caused a steady increase in groundwater withdrawal and groundwater depletion. One of the effects of groundwater pumping is the reduction in
streamflow through capture of groundwater recharge, with detrimental effects
on aquatic ecosystems. The degree to which groundwater withdrawal affects
streamflow or groundwater storage depends on the nature of the
groundwater–surface water interaction (GWSI). So far, analytical solutions that have been derived to calculate the impact of groundwater on streamflow
depletion involve single wells and streams and do not allow the GWSI to
shift from connected to disconnected, i.e. from a situation with two-way interaction to one with a one-way interaction between groundwater and surface water. Including this shift and also analysing the effects of many wells requires numerical groundwater models that are expensive to set up.
Here, we introduce an analytical framework based on a simple lumped
conceptual model that allows us to estimate to what extent groundwater withdrawal affects groundwater heads and streamflow at regional scales. It
accounts for a shift in GWSI, calculates at which critical withdrawal rate
such a shift is expected, and when it is likely to occur after withdrawal commences. It also provides estimates of streamflow depletion and which part
of the groundwater withdrawal comes out of groundwater storage and which
parts from a reduction in streamflow. After a local sensitivity analysis,
the framework is combined with parameters and inputs from a global
hydrological model and subsequently used to provide global maps of critical
withdrawal rates and timing, the areas where current withdrawal exceeds
critical limits and maps of groundwater and streamflow depletion rates that result from groundwater withdrawal. The resulting global
depletion rates are compared with estimates from in situ observations and regional and global groundwater models and satellites. Pairing of the
analytical framework with more complex global hydrological models presents a
screening tool for fast first-order assessments of regional-scale
groundwater sustainability and for supporting hydro-economic models that require simple relationships between groundwater withdrawal rates and the evolution of pumping costs and environmental externalities.</p> |
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