12 research outputs found
Assessing the water balance of the Upper Rhine Graben hydrosystem
International audienceThe Upper Rhine alluvial aquifer is an important transboundary water resource. However, as in many alluvial systems, the aquifer inflows and outflows are not precisely known because of the difficulty of estimating the river infiltration flux and the boundary subsurface flow. To provide a thorough representation of the aquifer system, a coupled surface-subsurface model was applied to the whole aquifer basin, and several parameter sets were tested to investigate the uncertainty due to poorly known parameters (e.g. aquifer transmissivity computed by an inverse model, river bed characteristics). Twelve simulations were run and analyzed using standard statistical criteria and also a more advanced statistical method, the Karhunen LoÚve transform (KLT). This analysis showed that, although the model performed reasonably well, some piezometric level underestimations persisted in the south of the basin. An accurate representation of the aquifer behaviour would require river infiltration and the functioning of irrigation canals in the Hardt area to be taken into account. It also appeared that increasing the maximum river infiltration flow deteriorated the quality of the results. River infiltration to the aquifer was estimated to represent about 80% of the aquifer inflows with a mean annual value around 115 ± 16.5 m3/s, thus with an uncertainty of 14%. This quantity is larger than estimated in previous studies but is in agreement with some results obtained during low water periods. This important conclusion highlights the vulnerability of the Upper Rhine Graben aquifer to pollution from the rivers and to climate change since it is highly probable that the rivers' regimes will be affected by reduced snow cover on the neighbouring mountain ranges
Modeling the influence of climate change on groundwater Upper Rhine
Cette recherche vise, dans un premier temps, Ă amĂ©liorer la connaissance du fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur entre BĂąle et Lauterbourg, sur une pĂ©riode de temps prĂ©sent (janvier 1986 Ă dĂ©cembre 2002), puis, dans un deuxiĂšme temps, Ă Ă©valuer lâimpact du changement climatique sur lâaquifĂšre. Pour obtenir ces rĂ©sultats, nous avons utilisĂ© le modĂšle hydrogĂ©ologique HPP-INV (Chardigny, 1997) pour le calage de diffĂ©rents paramĂštres par mĂ©thode inverse, pour Ă©valuer le fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur en temps prĂ©sent. Ce modĂšle, associĂ© Ă un modĂšle hydrologique que nous avons dĂ©veloppĂ© pour lâoccasion, nous a permis de calculer les Ă©volutions piĂ©zomĂ©triques et de dĂ©bits dans les riviĂšres pour les 2 horizons futurs par rapport la pĂ©riode de temps prĂ©sent. Nous avons dâabord caractĂ©risĂ© lâaquifĂšre et dĂ©fini son fonctionnement. Au niveau de la hauteur piĂ©zomĂ©trique et du dĂ©bit dans les riviĂšres de plaine, nous avons identifiĂ© le mois de fĂ©vrier comme le mois des hautes eaux et le mois de septembre comme celui des basses eaux. A lâinverse, le Rhin suit un rĂ©gime nivo-glaciaire, soit une pĂ©riode dâĂ©tiage en hiver et une pĂ©riode de pointe durant lâĂ©tĂ©. Nous avons Ă©galement mis en Ă©vidence lâimportance des Ă©changes nappe-riviĂšres dans le fonctionnement de lâaquifĂšre, qui reprĂ©sentent 59 % du dĂ©bit entrant et 87 % du dĂ©bit sortant par rapport Ă la nappe phrĂ©atique. Lâimpact du changement climatique sur lâaquifĂšre est ensuite Ă©tudiĂ© selon 3 scĂ©narios dâĂ©mission de gaz Ă effet de serre dĂ©veloppĂ©s par le GIEC (Groupement dâexperts Intergouvernementaux sur lâEvolution du Climat) : un scĂ©nario optimiste, un scĂ©nario pessimiste et un scĂ©nario intermĂ©diaire. Ces 3 scĂ©narios dâĂ©missions de gaz Ă effet de serre ont permis la crĂ©ation de 9 scĂ©narios mĂ©tĂ©orologiques, utilisĂ©s pour les prĂ©visions sur 2 horizons futurs par rapport au temps prĂ©sent (aoĂ»t 1961 Ă juillet 2000) : un futur proche (aoĂ»t 2046 Ă juillet 2065) et un futur lointain (aoĂ»t 2081 Ă juillet 2098). Nous avons dĂ©terminĂ© que pour la pĂ©riode de futur proche, lâĂ©volution piĂ©zomĂ©trique calculĂ©e dĂ©pend du scĂ©nario mĂ©tĂ©orologique. En effet, certains scĂ©narios prĂ©voient un abaissement non significatif du niveau de la nappe, alors que dâautres prĂ©voient une Ă©lĂ©vation. Enfin, un dernier prĂ©voit une Ă©lĂ©vation du niveau de la nappe dans sa moitiĂ© Sud et un abaissement dans sa moitiĂ© Nord. Pour la pĂ©riode de futur lointain, certaines prĂ©visions prĂ©sentent un abaissement du niveau de la nappe, plus important pour le scĂ©nario climatique le plus pessimiste. Les autres scĂ©narios prĂ©sentent une Ă©lĂ©vation globale du niveau de la nappe, trĂšs variable selon le scĂ©nario mĂ©tĂ©orologique.Concernant le dĂ©bit dans les riviĂšres, tous les scĂ©narios prĂ©voient la mĂȘme tendance pour les 2 horizons futurs. Le Rhin prĂ©sente une diminution du dĂ©bit estival, soit son dĂ©bit de pointe, et une augmentation de son dĂ©bit hivernal, soit son dĂ©bit dâĂ©tiage ; ce phĂ©nomĂšne, plus important pour la pĂ©riode de futur lointain que pour la pĂ©riode de futur proche, montre une modification du rĂ©gime du Rhin vers un rĂ©gime pluvio-nival. Pour les autres riviĂšres, nous avons observĂ© une diminution du dĂ©bit dâĂ©tiage et une augmentation du dĂ©bit de pointe, plus importantes pour la pĂ©riode de futur lointain (entre -46% et -8% pour le dĂ©bit dâĂ©tiage, et entre +32% et +94% pour le dĂ©bit de pointe) que pour la pĂ©riode de futur proche (entre -42% et -6% pour le dĂ©bit dâĂ©tiage, entre +0% et +102% pour le dĂ©bit de pointe).This research aims to, firstly, improve the understanding of the functioning of Upper Rhine aquifer between Basel and Lauterbourg during present time (January 1986-December 2002) and, secondly, assess the impact of climate change on the aquifer. To obtain these results, we used the hydrogeological model HPP- INV (Chardigny, 1997) for different parameters calibration by inverse method, to assess the functioning of the Upper Rhine aquifer in present time. Combining this model with a hydrological model that we developed for the occasion, we could calculate changes of piezometric level and flows in rivers for two future horizons of this report time period. We first characterized the aquifer and defined its operation. At the pressure head and flow in lowland rivers, we identified the month of February as the month of high water and September as the low water month. On the opposite the Rhine follows a snow and ice regime, a period of low water in winter and a peak during summer. We also highlighted the importance of exchange water table/river in the functioning of the aquifer, which represent 59% of the inflow and 87% of the outflow compared to the groundwater. The impact of climate change on the aquifer is then studied through three scenarios of greenhouse gas emissions developed by the IPCC (the Intergovernmental Panel on Climate Change): an optimistic scenario, a pessimistic scenario and an intermediate scenario. These three scenarios led to the creation of nine weather scenarios used to forecast 2 future horizons compared to the present time (August 1961-July 2000) : a near future (August 2046 to July 2065) and distant future (August 2081-July 2098). We determined that for the period of the near future, the calculated piezometric evolution depends on the weather scenario. In fact, some scenarios predict an insignificant lowering of the water, while others predict a rise. Finally, one foresees a raise of the water level in its southern half and a reduction in its northern half. For the distant future, some forecasts show a lowering of the water, the most important diminution for the pessimistic climate scenario. Other scenarios show an overall rise of the water level, variable depending on the weather scenario. Concerning the rivers flows, all scenarios predict the same trend for the two future horizons. The Rhine has a reduced summer flow - its peak flow - and an increase in winter flows - its low flow. This phenomenon, more important for the distant future compared to the near future, shows a shift of the Rhine regime to a snow and rain regime. For other rivers, we observed a decrease in low flows and an increase of the peak flow, more important for the distant future period (between -46% and -8% for low flows, and between +32% and +94% for the peak flow) than the near futur
Modeling the influence of climate change on groundwater Upper Rhine
Cette recherche vise, dans un premier temps, Ă amĂ©liorer la connaissance du fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur entre BĂąle et Lauterbourg, sur une pĂ©riode de temps prĂ©sent (janvier 1986 Ă dĂ©cembre 2002), puis, dans un deuxiĂšme temps, Ă Ă©valuer lâimpact du changement climatique sur lâaquifĂšre. Pour obtenir ces rĂ©sultats, nous avons utilisĂ© le modĂšle hydrogĂ©ologique HPP-INV (Chardigny, 1997) pour le calage de diffĂ©rents paramĂštres par mĂ©thode inverse, pour Ă©valuer le fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur en temps prĂ©sent. Ce modĂšle, associĂ© Ă un modĂšle hydrologique que nous avons dĂ©veloppĂ© pour lâoccasion, nous a permis de calculer les Ă©volutions piĂ©zomĂ©triques et de dĂ©bits dans les riviĂšres pour les 2 horizons futurs par rapport la pĂ©riode de temps prĂ©sent. Nous avons dâabord caractĂ©risĂ© lâaquifĂšre et dĂ©fini son fonctionnement. Au niveau de la hauteur piĂ©zomĂ©trique et du dĂ©bit dans les riviĂšres de plaine, nous avons identifiĂ© le mois de fĂ©vrier comme le mois des hautes eaux et le mois de septembre comme celui des basses eaux. A lâinverse, le Rhin suit un rĂ©gime nivo-glaciaire, soit une pĂ©riode dâĂ©tiage en hiver et une pĂ©riode de pointe durant lâĂ©tĂ©. Nous avons Ă©galement mis en Ă©vidence lâimportance des Ă©changes nappe-riviĂšres dans le fonctionnement de lâaquifĂšre, qui reprĂ©sentent 59 % du dĂ©bit entrant et 87 % du dĂ©bit sortant par rapport Ă la nappe phrĂ©atique. Lâimpact du changement climatique sur lâaquifĂšre est ensuite Ă©tudiĂ© selon 3 scĂ©narios dâĂ©mission de gaz Ă effet de serre dĂ©veloppĂ©s par le GIEC (Groupement dâexperts Intergouvernementaux sur lâEvolution du Climat) : un scĂ©nario optimiste, un scĂ©nario pessimiste et un scĂ©nario intermĂ©diaire. Ces 3 scĂ©narios dâĂ©missions de gaz Ă effet de serre ont permis la crĂ©ation de 9 scĂ©narios mĂ©tĂ©orologiques, utilisĂ©s pour les prĂ©visions sur 2 horizons futurs par rapport au temps prĂ©sent (aoĂ»t 1961 Ă juillet 2000) : un futur proche (aoĂ»t 2046 Ă juillet 2065) et un futur lointain (aoĂ»t 2081 Ă juillet 2098). Nous avons dĂ©terminĂ© que pour la pĂ©riode de futur proche, lâĂ©volution piĂ©zomĂ©trique calculĂ©e dĂ©pend du scĂ©nario mĂ©tĂ©orologique. En effet, certains scĂ©narios prĂ©voient un abaissement non significatif du niveau de la nappe, alors que dâautres prĂ©voient une Ă©lĂ©vation. Enfin, un dernier prĂ©voit une Ă©lĂ©vation du niveau de la nappe dans sa moitiĂ© Sud et un abaissement dans sa moitiĂ© Nord. Pour la pĂ©riode de futur lointain, certaines prĂ©visions prĂ©sentent un abaissement du niveau de la nappe, plus important pour le scĂ©nario climatique le plus pessimiste. Les autres scĂ©narios prĂ©sentent une Ă©lĂ©vation globale du niveau de la nappe, trĂšs variable selon le scĂ©nario mĂ©tĂ©orologique.Concernant le dĂ©bit dans les riviĂšres, tous les scĂ©narios prĂ©voient la mĂȘme tendance pour les 2 horizons futurs. Le Rhin prĂ©sente une diminution du dĂ©bit estival, soit son dĂ©bit de pointe, et une augmentation de son dĂ©bit hivernal, soit son dĂ©bit dâĂ©tiage ; ce phĂ©nomĂšne, plus important pour la pĂ©riode de futur lointain que pour la pĂ©riode de futur proche, montre une modification du rĂ©gime du Rhin vers un rĂ©gime pluvio-nival. Pour les autres riviĂšres, nous avons observĂ© une diminution du dĂ©bit dâĂ©tiage et une augmentation du dĂ©bit de pointe, plus importantes pour la pĂ©riode de futur lointain (entre -46% et -8% pour le dĂ©bit dâĂ©tiage, et entre +32% et +94% pour le dĂ©bit de pointe) que pour la pĂ©riode de futur proche (entre -42% et -6% pour le dĂ©bit dâĂ©tiage, entre +0% et +102% pour le dĂ©bit de pointe).This research aims to, firstly, improve the understanding of the functioning of Upper Rhine aquifer between Basel and Lauterbourg during present time (January 1986-December 2002) and, secondly, assess the impact of climate change on the aquifer. To obtain these results, we used the hydrogeological model HPP- INV (Chardigny, 1997) for different parameters calibration by inverse method, to assess the functioning of the Upper Rhine aquifer in present time. Combining this model with a hydrological model that we developed for the occasion, we could calculate changes of piezometric level and flows in rivers for two future horizons of this report time period. We first characterized the aquifer and defined its operation. At the pressure head and flow in lowland rivers, we identified the month of February as the month of high water and September as the low water month. On the opposite the Rhine follows a snow and ice regime, a period of low water in winter and a peak during summer. We also highlighted the importance of exchange water table/river in the functioning of the aquifer, which represent 59% of the inflow and 87% of the outflow compared to the groundwater. The impact of climate change on the aquifer is then studied through three scenarios of greenhouse gas emissions developed by the IPCC (the Intergovernmental Panel on Climate Change): an optimistic scenario, a pessimistic scenario and an intermediate scenario. These three scenarios led to the creation of nine weather scenarios used to forecast 2 future horizons compared to the present time (August 1961-July 2000) : a near future (August 2046 to July 2065) and distant future (August 2081-July 2098). We determined that for the period of the near future, the calculated piezometric evolution depends on the weather scenario. In fact, some scenarios predict an insignificant lowering of the water, while others predict a rise. Finally, one foresees a raise of the water level in its southern half and a reduction in its northern half. For the distant future, some forecasts show a lowering of the water, the most important diminution for the pessimistic climate scenario. Other scenarios show an overall rise of the water level, variable depending on the weather scenario. Concerning the rivers flows, all scenarios predict the same trend for the two future horizons. The Rhine has a reduced summer flow - its peak flow - and an increase in winter flows - its low flow. This phenomenon, more important for the distant future compared to the near future, shows a shift of the Rhine regime to a snow and rain regime. For other rivers, we observed a decrease in low flows and an increase of the peak flow, more important for the distant future period (between -46% and -8% for low flows, and between +32% and +94% for the peak flow) than the near futur
Modélisation de l'influence du changement climatique sur la nappe phréatique du Rhin Supérieur
This research aims to, firstly, improve the understanding of the functioning of Upper Rhine aquifer between Basel and Lauterbourg during present time (January 1986-December 2002) and, secondly, assess the impact of climate change on the aquifer. To obtain these results, we used the hydrogeological model HPP- INV (Chardigny, 1997) for different parameters calibration by inverse method, to assess the functioning of the Upper Rhine aquifer in present time. Combining this model with a hydrological model that we developed for the occasion, we could calculate changes of piezometric level and flows in rivers for two future horizons of this report time period. We first characterized the aquifer and defined its operation. At the pressure head and flow in lowland rivers, we identified the month of February as the month of high water and September as the low water month. On the opposite the Rhine follows a snow and ice regime, a period of low water in winter and a peak during summer. We also highlighted the importance of exchange water table/river in the functioning of the aquifer, which represent 59% of the inflow and 87% of the outflow compared to the groundwater. The impact of climate change on the aquifer is then studied through three scenarios of greenhouse gas emissions developed by the IPCC (the Intergovernmental Panel on Climate Change): an optimistic scenario, a pessimistic scenario and an intermediate scenario. These three scenarios led to the creation of nine weather scenarios used to forecast 2 future horizons compared to the present time (August 1961-July 2000) : a near future (August 2046 to July 2065) and distant future (August 2081-July 2098). We determined that for the period of the near future, the calculated piezometric evolution depends on the weather scenario. In fact, some scenarios predict an insignificant lowering of the water, while others predict a rise. Finally, one foresees a raise of the water level in its southern half and a reduction in its northern half. For the distant future, some forecasts show a lowering of the water, the most important diminution for the pessimistic climate scenario. Other scenarios show an overall rise of the water level, variable depending on the weather scenario. Concerning the rivers flows, all scenarios predict the same trend for the two future horizons. The Rhine has a reduced summer flow - its peak flow - and an increase in winter flows - its low flow. This phenomenon, more important for the distant future compared to the near future, shows a shift of the Rhine regime to a snow and rain regime. For other rivers, we observed a decrease in low flows and an increase of the peak flow, more important for the distant future period (between -46% and -8% for low flows, and between +32% and +94% for the peak flow) than the near futureCette recherche vise, dans un premier temps, Ă amĂ©liorer la connaissance du fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur entre BĂąle et Lauterbourg, sur une pĂ©riode de temps prĂ©sent (janvier 1986 Ă dĂ©cembre 2002), puis, dans un deuxiĂšme temps, Ă Ă©valuer lâimpact du changement climatique sur lâaquifĂšre. Pour obtenir ces rĂ©sultats, nous avons utilisĂ© le modĂšle hydrogĂ©ologique HPP-INV (Chardigny, 1997) pour le calage de diffĂ©rents paramĂštres par mĂ©thode inverse, pour Ă©valuer le fonctionnement de lâaquifĂšre du Rhin SupĂ©rieur en temps prĂ©sent. Ce modĂšle, associĂ© Ă un modĂšle hydrologique que nous avons dĂ©veloppĂ© pour lâoccasion, nous a permis de calculer les Ă©volutions piĂ©zomĂ©triques et de dĂ©bits dans les riviĂšres pour les 2 horizons futurs par rapport la pĂ©riode de temps prĂ©sent. Nous avons dâabord caractĂ©risĂ© lâaquifĂšre et dĂ©fini son fonctionnement. Au niveau de la hauteur piĂ©zomĂ©trique et du dĂ©bit dans les riviĂšres de plaine, nous avons identifiĂ© le mois de fĂ©vrier comme le mois des hautes eaux et le mois de septembre comme celui des basses eaux. A lâinverse, le Rhin suit un rĂ©gime nivo-glaciaire, soit une pĂ©riode dâĂ©tiage en hiver et une pĂ©riode de pointe durant lâĂ©tĂ©. Nous avons Ă©galement mis en Ă©vidence lâimportance des Ă©changes nappe-riviĂšres dans le fonctionnement de lâaquifĂšre, qui reprĂ©sentent 59 % du dĂ©bit entrant et 87 % du dĂ©bit sortant par rapport Ă la nappe phrĂ©atique. Lâimpact du changement climatique sur lâaquifĂšre est ensuite Ă©tudiĂ© selon 3 scĂ©narios dâĂ©mission de gaz Ă effet de serre dĂ©veloppĂ©s par le GIEC (Groupement dâexperts Intergouvernementaux sur lâEvolution du Climat) : un scĂ©nario optimiste, un scĂ©nario pessimiste et un scĂ©nario intermĂ©diaire. Ces 3 scĂ©narios dâĂ©missions de gaz Ă effet de serre ont permis la crĂ©ation de 9 scĂ©narios mĂ©tĂ©orologiques, utilisĂ©s pour les prĂ©visions sur 2 horizons futurs par rapport au temps prĂ©sent (aoĂ»t 1961 Ă juillet 2000) : un futur proche (aoĂ»t 2046 Ă juillet 2065) et un futur lointain (aoĂ»t 2081 Ă juillet 2098). Nous avons dĂ©terminĂ© que pour la pĂ©riode de futur proche, lâĂ©volution piĂ©zomĂ©trique calculĂ©e dĂ©pend du scĂ©nario mĂ©tĂ©orologique. En effet, certains scĂ©narios prĂ©voient un abaissement non significatif du niveau de la nappe, alors que dâautres prĂ©voient une Ă©lĂ©vation. Enfin, un dernier prĂ©voit une Ă©lĂ©vation du niveau de la nappe dans sa moitiĂ© Sud et un abaissement dans sa moitiĂ© Nord. Pour la pĂ©riode de futur lointain, certaines prĂ©visions prĂ©sentent un abaissement du niveau de la nappe, plus important pour le scĂ©nario climatique le plus pessimiste. Les autres scĂ©narios prĂ©sentent une Ă©lĂ©vation globale du niveau de la nappe, trĂšs variable selon le scĂ©nario mĂ©tĂ©orologique.Concernant le dĂ©bit dans les riviĂšres, tous les scĂ©narios prĂ©voient la mĂȘme tendance pour les 2 horizons futurs. Le Rhin prĂ©sente une diminution du dĂ©bit estival, soit son dĂ©bit de pointe, et une augmentation de son dĂ©bit hivernal, soit son dĂ©bit dâĂ©tiage ; ce phĂ©nomĂšne, plus important pour la pĂ©riode de futur lointain que pour la pĂ©riode de futur proche, montre une modification du rĂ©gime du Rhin vers un rĂ©gime pluvio-nival. Pour les autres riviĂšres, nous avons observĂ© une diminution du dĂ©bit dâĂ©tiage et une augmentation du dĂ©bit de pointe, plus importantes pour la pĂ©riode de futur lointain (entre -46% et -8% pour le dĂ©bit dâĂ©tiage, et entre +32% et +94% pour le dĂ©bit de pointe) que pour la pĂ©riode de futur proche (entre -42% et -6% pour le dĂ©bit dâĂ©tiage, entre +0% et +102% pour le dĂ©bit de pointe)
Modélisation de l'influence du changement climatique sur la nappe phréatique du Rhin Supérieur
Cette recherche vise, dans un premier temps, Ă amĂ©liorer la connaissance du fonctionnement de l aquifĂšre du Rhin SupĂ©rieur entre BĂąle et Lauterbourg, sur une pĂ©riode de temps prĂ©sent (janvier 1986 Ă dĂ©cembre 2002), puis, dans un deuxiĂšme temps, Ă Ă©valuer l impact du changement climatique sur l aquifĂšre. Pour obtenir ces rĂ©sultats, nous avons utilisĂ© le modĂšle hydrogĂ©ologique HPP-INV (Chardigny, 1997) pour le calage de diffĂ©rents paramĂštres par mĂ©thode inverse, pour Ă©valuer le fonctionnement de l aquifĂšre du Rhin SupĂ©rieur en temps prĂ©sent. Ce modĂšle, associĂ© Ă un modĂšle hydrologique que nous avons dĂ©veloppĂ© pour l occasion, nous a permis de calculer les Ă©volutions piĂ©zomĂ©triques et de dĂ©bits dans les riviĂšres pour les 2 horizons futurs par rapport la pĂ©riode de temps prĂ©sent. Nous avons d abord caractĂ©risĂ© l aquifĂšre et dĂ©fini son fonctionnement. Au niveau de la hauteur piĂ©zomĂ©trique et du dĂ©bit dans les riviĂšres de plaine, nous avons identifiĂ© le mois de fĂ©vrier comme le mois des hautes eaux et le mois de septembre comme celui des basses eaux. A l inverse, le Rhin suit un rĂ©gime nivo-glaciaire, soit une pĂ©riode d Ă©tiage en hiver et une pĂ©riode de pointe durant l Ă©tĂ©. Nous avons Ă©galement mis en Ă©vidence l importance des Ă©changes nappe-riviĂšres dans le fonctionnement de l aquifĂšre, qui reprĂ©sentent 59 % du dĂ©bit entrant et 87 % du dĂ©bit sortant par rapport Ă la nappe phrĂ©atique. L impact du changement climatique sur l aquifĂšre est ensuite Ă©tudiĂ© selon 3 scĂ©narios d Ă©mission de gaz Ă effet de serre dĂ©veloppĂ©s par le GIEC (Groupement d experts Intergouvernementaux sur l Evolution du Climat) : un scĂ©nario optimiste, un scĂ©nario pessimiste et un scĂ©nario intermĂ©diaire. Ces 3 scĂ©narios d Ă©missions de gaz Ă effet de serre ont permis la crĂ©ation de 9 scĂ©narios mĂ©tĂ©orologiques, utilisĂ©s pour les prĂ©visions sur 2 horizons futurs par rapport au temps prĂ©sent (aoĂ»t 1961 Ă juillet 2000) : un futur proche (aoĂ»t 2046 Ă juillet 2065) et un futur lointain (aoĂ»t 2081 Ă juillet 2098). Nous avons dĂ©terminĂ© que pour la pĂ©riode de futur proche, l Ă©volution piĂ©zomĂ©trique calculĂ©e dĂ©pend du scĂ©nario mĂ©tĂ©orologique. En effet, certains scĂ©narios prĂ©voient un abaissement non significatif du niveau de la nappe, alors que d autres prĂ©voient une Ă©lĂ©vation. Enfin, un dernier prĂ©voit une Ă©lĂ©vation du niveau de la nappe dans sa moitiĂ© Sud et un abaissement dans sa moitiĂ© Nord. Pour la pĂ©riode de futur lointain, certaines prĂ©visions prĂ©sentent un abaissement du niveau de la nappe, plus important pour le scĂ©nario climatique le plus pessimiste. Les autres scĂ©narios prĂ©sentent une Ă©lĂ©vation globale du niveau de la nappe, trĂšs variable selon le scĂ©nario mĂ©tĂ©orologique.Concernant le dĂ©bit dans les riviĂšres, tous les scĂ©narios prĂ©voient la mĂȘme tendance pour les 2 horizons futurs. Le Rhin prĂ©sente une diminution du dĂ©bit estival, soit son dĂ©bit de pointe, et une augmentation de son dĂ©bit hivernal, soit son dĂ©bit d Ă©tiage ; ce phĂ©nomĂšne, plus important pour la pĂ©riode de futur lointain que pour la pĂ©riode de futur proche, montre une modification du rĂ©gime du Rhin vers un rĂ©gime pluvio-nival. Pour les autres riviĂšres, nous avons observĂ© une diminution du dĂ©bit d Ă©tiage et une augmentation du dĂ©bit de pointe, plus importantes pour la pĂ©riode de futur lointain (entre -46% et -8% pour le dĂ©bit d Ă©tiage, et entre +32% et +94% pour le dĂ©bit de pointe) que pour la pĂ©riode de futur proche (entre -42% et -6% pour le dĂ©bit d Ă©tiage, entre +0% et +102% pour le dĂ©bit de pointe).This research aims to, firstly, improve the understanding of the functioning of Upper Rhine aquifer between Basel and Lauterbourg during present time (January 1986-December 2002) and, secondly, assess the impact of climate change on the aquifer. To obtain these results, we used the hydrogeological model HPP- INV (Chardigny, 1997) for different parameters calibration by inverse method, to assess the functioning of the Upper Rhine aquifer in present time. Combining this model with a hydrological model that we developed for the occasion, we could calculate changes of piezometric level and flows in rivers for two future horizons of this report time period. We first characterized the aquifer and defined its operation. At the pressure head and flow in lowland rivers, we identified the month of February as the month of high water and September as the low water month. On the opposite the Rhine follows a snow and ice regime, a period of low water in winter and a peak during summer. We also highlighted the importance of exchange water table/river in the functioning of the aquifer, which represent 59% of the inflow and 87% of the outflow compared to the groundwater. The impact of climate change on the aquifer is then studied through three scenarios of greenhouse gas emissions developed by the IPCC (the Intergovernmental Panel on Climate Change): an optimistic scenario, a pessimistic scenario and an intermediate scenario. These three scenarios led to the creation of nine weather scenarios used to forecast 2 future horizons compared to the present time (August 1961-July 2000) : a near future (August 2046 to July 2065) and distant future (August 2081-July 2098). We determined that for the period of the near future, the calculated piezometric evolution depends on the weather scenario. In fact, some scenarios predict an insignificant lowering of the water, while others predict a rise. Finally, one foresees a raise of the water level in its southern half and a reduction in its northern half. For the distant future, some forecasts show a lowering of the water, the most important diminution for the pessimistic climate scenario. Other scenarios show an overall rise of the water level, variable depending on the weather scenario. Concerning the rivers flows, all scenarios predict the same trend for the two future horizons. The Rhine has a reduced summer flow - its peak flow - and an increase in winter flows - its low flow. This phenomenon, more important for the distant future compared to the near future, shows a shift of the Rhine regime to a snow and rain regime. For other rivers, we observed a decrease in low flows and an increase of the peak flow, more important for the distant future period (between -46% and -8% for low flows, and between +32% and +94% for the peak flow) than the near futureSTRASBOURG-Bib.electronique 063 (674829902) / SudocSudocFranceF
Successful Thrombectomy Improves Functional Outcome in Tandem Occlusions with a Large Ischemic Core
International audienceBackground: Emergent stenting in tandem occlusions and mechanical thrombectomy (MT) of acute ischemic stroke related to large vessel occlusion (LVO-AIS) with a large core are tested independently. We aim to assess the impact of reperfusion with MT in patients with LVO-AIS with a large core and a tandem occlusion and to compare the safety of reperfusion between large core with tandem and nontandem occlusions in current practice. Methods: We analyzed data of all consecutive patients included in the prospective Endovascular Treatment in Ischemic Stroke Registry in France between January 2015 and March 2023 who presented with a pretreatment ASPECTS (Alberta Stroke Program Early CT Score) of 0â5 and angiographically proven tandem occlusion. The primary end point was a favorable outcome defined by a modified Rankin Scale (mRS) score of 0â3 at 90 days. Results: Among 262 included patients with a tandem occlusion and ASPECTS 0â5, 203 patients (77.5%) had a successful reperfusion (modified Thrombolysis in Cerebral Infarction grade 2b-3). Reperfused patients had a favorable shift in the overall mRS score distribution (adjusted odds ratio [aOR], 1.57 [1.22â2.03]; P < 0.001), higher rates of mRS score 0â3 (aOR, 7.03 [2.60â19.01]; P < 0.001) and mRS score 0â2 at 90 days (aOR, 3.85 [1.39â10.68]; P = 0.009) compared with nonreperfused. There was a trend between the occurrence of successful reperfusion and a decreased rate of symptomatic intracranial hemorrhage (aOR, 0.5 [0.22â1.13]; P = 0.096). Similar safety outcomes were observed after large core reperfusion in tandem and nontandem occlusions. Conclusions: Successful reperfusion was associated with a higher rate of favorable outcome in large core LVO-AIS with a tandem occlusion, with a safety profile similar to nontandem occlusion
Effect of general anaesthesia on functional outcome in patients with anterior circulation ischaemic stroke having endovascular thrombectomy versus standard care: a meta-analysis of individual patient data
Background:
General anaesthesia (GA) during endovascular thrombectomy has been associated with worse patient outcomes in observational studies compared with patients treated without GA. We assessed functional outcome in ischaemic stroke patients with large vessel anterior circulation occlusion undergoing endovascular thrombectomy under GA, versus thrombectomy not under GA (with or without sedation) versus standard care (ie, no thrombectomy), stratified by the use of GA versus standard care.
Methods:
For this meta-analysis, patient-level data were pooled from all patients included in randomised trials in PuMed published between Jan 1, 2010, and May 31, 2017, that compared endovascular thrombectomy predominantly done with stent retrievers with standard care in anterior circulation ischaemic stroke patients (HERMES Collaboration). The primary outcome was functional outcome assessed by ordinal analysis of the modified Rankin scale (mRS) at 90 days in the GA and non-GA subgroups of patients treated with endovascular therapy versus those patients treated with standard care, adjusted for baseline prognostic variables. To account for between-trial variance we used mixed-effects modelling with a random effect for trials incorporated in all models. Bias was assessed using the Cochrane method. The meta-analysis was prospectively designed, but not registered.
Findings:
Seven trials were identified by our search; of 1764 patients included in these trials, 871 were allocated to endovascular thrombectomy and 893 were assigned standard care. After exclusion of 74 patients (72 did not undergo the procedure and two had missing data on anaesthetic strategy), 236 (30%) of 797 patients who had endovascular procedures were treated under GA. At baseline, patients receiving GA were younger and had a shorter delay between stroke onset and randomisation but they had similar pre-treatment clinical severity compared with patients who did not have GA. Endovascular thrombectomy improved functional outcome at 3 months both in patients who had GA (adjusted common odds ratio (cOR) 1·52, 95% CI 1·09â2·11, p=0·014) and in those who did not have GA (adjusted cOR 2·33, 95% CI 1·75â3·10, p<0·0001) versus standard care. However, outcomes were significantly better for patients who did not receive GA versus those who received GA (covariate-adjusted cOR 1·53, 95% CI 1·14â2·04, p=0·0044). The risk of bias and variability between studies was assessed to be low.
Interpretation:
Worse outcomes after endovascular thrombectomy were associated with GA, after adjustment for baseline prognostic variables. These data support avoidance of GA whenever possible. The procedure did, however, remain effective versus standard care in patients treated under GA, indicating that treatment should not be withheld in those who require anaesthesia for medical reasons