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| Titel |
Dynamic Attribution of Global Water Demand to Surface Water and Groundwater Resources: Effects of Abstractions and Return Flows on River Discharge |
| VerfasserIn |
Inge de Graaf, Rens van Beek, Yoshi Wada, Marc Bierkens |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074522
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| Zusammenfassung |
| As human water demand is increasing worldwide, groundwater is abstracted at rates
that exceed groundwater recharge in many areas, resulting in depletion of existing
groundwater stocks. Most studies, that focus on human water consumption and water
stress indicate a gap between water demand and availability. However, between
studies very different assumptions are made on how water abstraction is divided
between surface water, groundwater, and other resources. Moreover, simplified
assumptions are used of the interactions between groundwater and surface water. Here,
we simulate at the global scale, the dynamic attribution of total water demand to
surface water and groundwater resources, based on actual water availability and
accounting for return flows and surface water- groundwater interactions. The global
hydrological model PCR-GLOBWB is used to simulate water storages, abstractions, and
return flows for the model period 1960-2010, with a daily time step at 0.5° x 0.5°
spatial resolution. Total water demand is defined as requirements for irrigation,
industry, and domestic use. Water abstractions are variably taken from surface water
and groundwater resources depending on availability of both resources. Return
flows of non-consumed abstracted water contribute to a single source; those of
irrigation recharging groundwater, those of industry and domestic use discharging to
surface waters. Groundwater abstractions are taken from renewable groundwater, or
when exceeding recharge from an alternative unlimited resource. This resource
consists of non-renewable groundwater, or non-local water, the former being an
estimate of groundwater depletion. Results show that worldwide the effect of water
abstractions is evident, especially on the magnitude and frequency of low flows when the
contribution of groundwater through baseflow is substantial. River regimes are minimally
affected by abstractions in industrial regions because of the high return flows. In
irrigated regions the effect of abstractions is clear and including return flows is
important as well. It increases groundwater storage and baseflow to the river channel.
Furthermore, simulated trends of water abstraction, and its attribution to surface water or
groundwater, strongly depend on whether return flows are included or not. Particularly on
the ratio of renewable to non-renewable and non-local water resources. Estimated
total groundwater abstraction for the year 2000 is 1100 km3y-1, of which ~35%
comes from reused irrigation water. Non-renewable-, or non-local water abstraction
is estimated to be ~560 km3y-1, which corresponds well with estimates from
previous studies. This term increases, mainly for intensively irrigated areas, to ~840
km3y-1 when return flows are not accounted for. The dynamic representation of
abstractions and return flows makes the model a suitable tool for assessing spatial
and temporal impacts of global water demand on hydrology and water resources. |
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