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| Titel |
Modeling of drainage and hay production over the Crau aquifer for analyzing the impact of global change on aquifer recharge |
| VerfasserIn |
Albert Olioso, Rémi Lecerf, Antoine Baillieux, André Chanzy, Françoise Ruget, Olivier Banton, Patrice Lecharpentier, Mohamed Alkassem Alosman, Stephane Ruy, Belen Gallego Elvira |
| 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 |
250076788
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| Zusammenfassung |
| The recharge of the aquifer in the Crau plain (550 km2, Southern Rhone Valley, France)
depends on the irrigation of 15000 ha of meadow using water withdrawn from the River
Durance through a dense network of channels. Traditional irrigation practice, since the XVIth
century, has consisted in flooding the grassland fields with a large amount of water, the excess
being infiltrated toward the water table. Today, the Crau aquifer holds the main resource in
water in the area (300 000 inhabitants) but changes in the agricultural practices and
progressive replacement of the irrigated meadows by urbanized area threaten the
sustainability of groundwater.
The distributed modeling of irrigated meadows together with the modeling of
groundwater has been undertaken for quantifying the contribution of the irrigation to the
recharge of the aquifer and to investigate possible evolution of hay production,
water drainage, evapotranspiration and water table under scenarios of climate and
land-use changes. The model combines a crop model (STICS) that simulates hay
production, evapotranspiration and water drainage, a multisimulation tool (MultiSimLib)
that allows to run STICS over each agricultural field in the aquifer perimeter, a
groundwater model MODFLOW to simulate the water table from recharge data (simulated
drainage).
Specific models were developed for simulating the spatial distribution of climate,
including scenario of changes for the 2025 – 2035 time period, soil properties (influenced by
irrigation), and agricultural practices (calendar and amount), in particular irrigation and hay
cutting. This step was crucial for correctly simulating hay production level and amount of
water used for irrigation.
Model results were evaluated thanks to plot experiments and information from farmers
(biomass production, downward water flow, quantity of irrigated water, cutting calendar-¦), a
network of piezometers and remote sensing maps of evapotranspiration.
Main results included:
- the proportion of irrigation water that contributes to the recharge of aquifer was
evaluated to 75 %, which represent 80% of the total recharge;
- increase in temperature in the future leads to an increase in hay production (+ 10% in
2030 compared to now)
- increase in potential evapotranspiration in the future leads to an increase of meadow
evapotranspiration by 10% which has a significant impact on the amount of irrigation
water required to sustain the level of aquifer recharge and the level of the water
table
- decrease in irrigated surfaces (-10% forecasted for 2030) results in a significant decrease
of aquifer recharge (- 8%) that may affect water resources in the area (amount almost
equivalent to water withdrawal for domestic use in the area)
- reduction in available water for irrigation directly affect the aquifer recharge: e.g. 30%
reduction in irrigation level result in a 35% reduction in drainage at the aquifer scale;
however, the production of hay would be just slightly affected.
This work was performed in the frame of Astuce et Tic project (French ministries
financial support) and Sirrimed project (European FP7 financial support). |
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