Climate change impacts on groundwater resource in South of France

Transcription

1 Climate change impacts on groundwater resource in South of France Yvan Caballero 1, Sandra Lanini 1, Pierre Le Cointe 2, Sandra Beranger 2 (1) BRGM French Geological Survey, Montpellier (France) (2) BRGM French Geological Survey, Toulouse (France) Contact: y.caballero@brgm.fr

2 Recharge to characterize groundwater resource? Infiltration of effective precipitation > 2

3 Necessary for water managers in the CC context Surface water projections available Chauveau et al. (2013) Present and future recharge? CC Adaptation plans > 3

4 Using Soil Water Balance methods for recharge mapping Uncertainty 3 effective rainfall simulation methods: Thornthwaite (1948) ETR PET if < Max SWC Runoff Dingman (2002) ETR decreasing exponential function Infiltration Coefficient Groundwater recharge or Thiery (2014) ETR quadratic function > 4

5 Using Soil Water Balance methods for recharge mapping INRA (1998) (1/ ) Soil Water Content map (mm) Effective rainfall map > 5

6 Sensitivity analysis of effective precipitation simulation Our Reference: SURFEX Soil Vegetation Transfer Scheme (Masson et al., 2013) Effective precipitation = SURFEX runoff + deep infiltration > 6

7 Sensitivity analysis of effective precipitation simulation Thornthwaite SWB Relative difference to SURFEX: SURFEX Dingman SWB Gardenia SWB > 7

8 From effective precipitation to recharge mapping > Using a infiltration coefficient (IC) map for effective rainfall partition X = Effective rainfall Different data for IC? Recharge with uncertainty (ER+ IC) > 8

9 Illustrating uncertainty linked to recharge by precipitation Mean annual recharge (mm) Uncertainty linked to IC (%) Mainly driven by the IC value > 9

10 Assessing climate change impact on recharge Mailles MCG Downscaling SAFRAN grid (8 x 8 km) Climatic Analogues Dayon (2016) Continuous simulation between 1981 and 2100 RCP 2.6 and GCMs (CSM1, CanESM2, NorESM1, IPSL, CNRM-CM3) (only 4 for RCP8.5) 10

11 Relative annual changes RCP 2.6 & 8.5 Mean annual change RCP 2.6 (%) Mean annual change RCP 8.5 (%) 11

12 Illustrating uncertainty linked to other recharge processes Basin/aquifer scale assessment SWB Recharge Recharge = Σ (Annual WL increase) ESPERE Tool Lanini et al. (2015), free Recharge = Annual base flow Linking base flow or piezometric levels to climate for CC impact assessment? numerical models or statistical downscaling or > 12

13 Conclusions Aquifer recharge groundwater resource but useful for water managers Simple SWB recharge estimation methods for recharge mapping with illustration of uncertainty of the main method components Can be assessed using basin/aquifer scale recharge estimations Can be used to explore the future situation in the CC context Overall deficit of aquifer recharge is projected in the south of France, reaching -50% in some regions raise new questions from water managers that generally need process modelling; > 13

14 References cited Chauveau, M., Chazot, S., Perrin, C., Bourgin, P.-Y., Sauquet, E., Vidal, J.-P., Rouchy, N., Martin, E., David, J., Norotte, T., Maugis, P., and de Lacaze, X.: (2013), Quels impacts des changements climatiques sur les eaux de surface en France à l horizon 2070?, La Houille Blanche, 4, Dingman S. L. (2002), Physical Hydrology, pp. 575, Waveland Press, 2nd edition, ISBN: Lanini, S., Caballero, Y., Seguin, J.-J., and Maréchal, J.-C., (2015), ESPERE - A Multiple-Method Microsoft Excel Application for Estimating Aquifer Recharge, Groundwater 54, no. 2: Mardhel, V., Frantar P., Uhan J. and Miso A. (2004). Index of development and persistence of the river networks as a component of regional groundwater vulnerability assessment in Slovenia. International conference on groundwater vulnerability assessment and mapping, Ustron, Poland, June 2004 Masson, V., P. Le Moigne, E. Martin, S. Faroux, A. Alias, R. Alkama, S. Belamari, A. Barbu, A. Boone, F. Bouyssel, P. Brousseau, E. Brun, J. -. Calvet, D. Carrer, B. Decharme, C. Delire, S. Donier, K. Essaouini, A. -. Gibelin, H. Giordani, F. Habets, M. Jidane, G. Kerdraon, E. Kourzeneva, M. Lafaysse, S. Lafont, C. Lebeaupin Brossier, A. Lemonsu, J. -. Mahfouf, P. Marguinaud, M. Mokhtari, S. Morin, G. Pigeon, R. Salgado, Y. Seity, F. Taillefer, G. Tanguy, P. Tulet, B. Vincendon, V. Vionnet and A. Voldoire (2013), The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of earth surface variables and fluxes, Geosci. Model Dev., 6(4), , doi: /gmd Scanlon, B. R., K. E. Keese, A. L. Flint, L. E. Flint, C. B. Gaye, W. M. Edmunds and I. Simmers (2006), Global synthesis of groundwater recharge in semiarid and arid regions, Hydrol.Process., 20(15), , doi: /hyp.6335 Thornthwaite, C. W. (1948), An approach toward a rational classification of climate, Geograph. Rev., 38, 55-94, Thiéry D. (2014). Logiciel GARDÉNIA, version 8.2. Guide d utilisation. Rapport BRGM/RP FR, mise à jour : Mai 2015 > 14