11 research outputs found
Impacts des changements climatiques sur la gestion des barrages-réservoirs du bassin de la Seine - Premiers résultats du projet Climaware
International audienceLes projections climatiques Ă©tablies par le GIECC indiquent que des changements significatifs dans les prĂ©cipitations et les tempĂ©ratures sont Ă attendre en Europe dans les prochaines dĂ©cennies, ce qui devrait impacter la disponibilitĂ© en eau. Le projet europĂ©en Climaware (2010-2013, financĂ© par IWRM-Net) a Ă©tĂ© montĂ© pour dĂ©velopper des mesures d'adaptation telles que des instruments de gestion intĂ©grĂ©e pour une gestion durable des ressources en eau tenant compte des changements climatiques. Au sein du projet, le cas d'Ă©tude sur la riviĂšre Seine se concentre sur l'adaptation de la gestion de barrages (et Ă©ventuellement de la capacitĂ© de stockage) pour deux objectifs principaux : le soutien d'Ă©tiage et l'Ă©crĂȘtement de crues, avec des enjeux socio-Ă©conomiques importants, en particulier dans la rĂ©gion parisienne. Les quatre grands barrages gĂ©rĂ©s par l'EPTB Seine Grands Lacs sont situĂ©s sur la partie amont du bassin sur quatre sous-bassins diffĂ©rents. Un modĂšle hydrologique semi-distribuĂ© a Ă©tĂ© dĂ©veloppĂ© pour simuler la transformation pluie-dĂ©bit sur le bassin. Le modĂšle a Ă©tĂ© calĂ© en utilisant les donnĂ©es de dĂ©bits naturalisĂ©s sur 25 stations hydromĂ©triques sur le bassin. Le modĂšle a ensuite Ă©tĂ© alimentĂ© par des projections climatiques dĂ©sagrĂ©gĂ©es issues de sept modĂšles climatiques diffĂ©rents. Les rĂ©sultats indiquent que les dĂ©bits d'Ă©tiage pourraient ĂȘtre significativement diminuĂ©s sur le bassin d'ici Ă 2050. Ceci appelle Ă dĂ©finir des stratĂ©gies de gestion adaptĂ©es. Plusieurs options seront testĂ©es pour tenir compte de ces modifications sur le bassin. / Climate projections established by the IPCC indicate that significant changes in precipitation and temperature are to be expected in Europe in the next decades, which should impact regional water availability. The Climaware European project (2010-2013, funded by IMWR-Net) was set up to develop adaptation measures such as integrated planning instruments for sustainable water resources management accounting for the impacts of climate change. Within the project, the Seine River case study focuses on the adaptation of dam management (and possibly dam storage capacity) for two main objectives: low-flow augmentation and flood alleviation, with important socio-economic stakes especially in the great Paris area. The four large reservoirs managed by the Seine Grands Lacs public basin authority, are situated on the upstream part of the basin on four different sub-basins. A semi-distributed hydrological model was developed to simulate the rainfall-runoff transformation on the basin. The model was calibrated using the naturalized flow data available on 25 gauging station across the basin. Then it was fed with climate projections downscaled from seven different climate models. Results indicate that low flows may be significantly reduced on the basin by 2050. This calls for defining adapted management strategies. Various options will be tested to account for these modifications on the basin
ModÚle intégré du fonctionnement hydrologique du bassin versant du Sassandra
Cette Ă©tude prĂ©sente la mise au point d'un modĂšle intĂ©grĂ© du fonctionnement hydrologique du bassin versant total du Sassandra en CĂŽte d'Ivoire (environ 75â000âkm2). Ce modĂšle permet d'analyser les effets des amĂ©nagements existants et planifiĂ©s sur les dĂ©bits. Il repose sur le couplage d'un modĂšle d'allocation des ressources en eau avec un modĂšle pluie-dĂ©bit. Le modĂšle repose sur une discrĂ©tisation en huit sous-bassins versants, pour lesquels les dĂ©bits mensuels ont Ă©tĂ© reconstituĂ©s grĂące Ă des mĂ©thodes hydrologiques simples Ă mettre en Ćuvre et robustes, donc bien adaptĂ©es au contexte opĂ©rationnel. Les principales incertitudes des rĂ©sultats de modĂ©lisation proviennent de la faible disponibilitĂ© des donnĂ©es, de la simplicitĂ© des outils et mĂ©thodes utilisĂ©s, et de la non-stationnaritĂ© liĂ©e Ă la rupture climatique observĂ©e sur la zone d'Ă©tude et ses effets sur la robustesse du paramĂ©trage et les performances du modĂšle pluie-dĂ©bit. L'acceptation de ces limitations est justifiĂ©e par les bĂ©nĂ©fices tirĂ©s de l'utilisation du modĂšle Ă des fins de planification. Les impacts des amĂ©nagements Ă l'amont de Buyo se traduisent par une augmentation bien plus marquĂ©e de la puissance garantie que de l'Ă©nergie moyenne sur les ouvrages aval. Ce rĂ©sultat est dĂ» Ă l'augmentation de la capacitĂ© totale de stockage, donc une capacitĂ© accrue Ă passer les Ă©pisodes de sĂ©cheresse, tandis qu'en annĂ©e moyenne, le niveau de rĂ©gulation des apports Ă Buyo est dĂ©jĂ trĂšs Ă©levĂ© et ne peut ĂȘtre amĂ©liorĂ© que marginalement
A pragmatic approach to assess the climate resilience of hydro projects
There is no doubt that the planet is warming quickly. What is uncertain, and hugely so, is the impact the warming will have on the climatologic and hydrologic processes that directly influence performance of existing and planned water-resources related projects, for example hydropower. Therefore, the prospect of climate change has become a key issue for the large dams/reservoirs community. This paper provides first an overview of the increasing awareness of climate change impacts on the performance and reliability of hydro projects within this community. Then, it presents a pragmatic approach to assess the climate resilience of hydro projects. This approach fully complies with the Hydropower Sector Climate Resilience Guide released by International Hydropower Association in 2019 [1]. The case study is a hydropower project on St Paul River in Liberia. The paper focuses on the methods and results of the Phase 3 climate stress test, namely the power generation performance under a wide range of different possible future climate scenarios. The modelling cascade is formed by the hydrological model GR4J and a hydropower model supported by Mike Hydro Basin software. It is used to simulate 35+ years of daily hydropower operation
Présentation du NEMO Edukit
article de 3 Pages et posterNational audienceL'objectif du présent article est de présenter le kit éducatif développé dans le cadre du réseau d'excellence NEMO (Network of excellence on Micro Optics) du 6Úme PCRD [1]. NEMO est un projet visant à rassembler des partenaires de plusieurs pays européen dans le domaine de la micro-optique. Pour convaincre les élÚves, dÚs l'école primaire et jusqu'à la fin du secondaire, des applications et du rÎle de l'optique et la micro-optique dans la vie quotidienne ou dans la recherche, plusieurs partenaires de NEMO ont collaborés à la création de ce kit éducatif
ĂlasticitĂ© des dĂ©bits aux prĂ©cipitations en Afrique sub-saharienne
L'estimation de l'Ă©lasticitĂ© des dĂ©bits aux prĂ©cipitations est prĂ©sentĂ©e pour un ensemble d'une cinquantaine de bassins versants situĂ©s en Afrique sub-saharienne. L'Ă©lasticitĂ© des dĂ©bits aux prĂ©cipitations est dĂ©finie ici comme le changement proportionnel de l'Ă©coulement moyen annuel divisĂ© par le changement proportionnel de la prĂ©cipitation moyenne annuelle. Elle dĂ©crit donc la sensibilitĂ© des dĂ©bits Ă des changements de prĂ©cipitations et s'avĂšre un outil utile pour Ă©valuer de maniĂšre simple, mais non simpliste, l'impact du changement climatique dans des projets relatifs Ă l'utilisation des ressources en eau. L'Ă©lasticitĂ© des dĂ©bits aux prĂ©cipitations est Ă©valuĂ©e ici de maniĂšre empirique grĂące Ă des estimateurs non-paramĂ©triques et des sĂ©ries historiques de dĂ©bit observĂ© et de prĂ©cipitation. Les rĂ©sultats indiquent que l'Ă©lasticitĂ© des dĂ©bits aux prĂ©cipitations est de l'ordre de 1 Ă 3 sur les bassins versants Ă©tudiĂ©s. Les anomalies des prĂ©cipitations sont donc amplifiĂ©es au niveau des Ă©coulements avec un facteur de 1 Ă 3. L'Ă©lasticitĂ© des dĂ©bits aux prĂ©cipitations diminue lorsqu'augmentent l'Ă©coulement moyen interannuel et le coefficient de ruissellement. En revanche, il ne semble pas exister de relation directe entre Ă©lasticitĂ© des dĂ©bits et superficie de bassin versant. La cartographie des rĂ©sultats ne rĂ©vĂšle pas non plus de facteurs physiques pouvant expliquer la variabilitĂ© des valeurs d'Ă©lasticitĂ©. De mĂȘme le type de climat ne semble pas un facteur explicatif de premier ordre
Are hydrologic-hydraulic coupling approaches able to reproduce Alex flash-flood dynamics and impacts on southeastern French headwaters?
International audienceDuring the last 5 years, south-eastern France experienced four deadly Mediterranean flash-floods: one in October 2015, two in November and December 2019 and the last one in October 2020, caused by the Storm Alex. The 2015 and 2019 events mostly affected small coastal catchments of the French Riviera (â100 km2) and (ii) in the context of significant topographic changes due to the flood. A continuous semi-distributed rainfall-runoff model has been coupled with the Basilisk software, which is based on state-of-the-art 2D hydraulic modelling (well-balanced finite volume method for shallow water equations) with adaptive grid refinement. The streamflow series and inundation extents simulated have be compared with available observations gathered from post-event surveys with a particular focus on two places (Saint-Martin-VĂ©subie and RoquebiliĂšre)
Are hydrologic-hydraulic coupling approaches able to reproduce Alex flash-flood dynamics and impacts on southeastern French headwaters?
International audienc
Que sait-on des précipitations en altitude dans les Andes semi-arides du Chili ? (What do we know about high-altitude precipitation in the semi-arid Andes of Chile?)
International audienceMapping precipitations on a regular grid is often required for hydrological and ecological modelling. The spatial interpolation methods are generally used to estimate such a distribution from ground-based measurements. In the case of mountainous areas, the estimation of precipitation amounts is still a challenging task and the results of spatial interpolation should be verified as much as possible. Here we describe a three-steps method for the validation of a precipitation map. This is used in the context of a mountainous semi-arid region, the Norte Chico in Chile (26°S-32°S). The implementation of this validation method showed the benefits of an interpolation method developed by ValĂ©ry [2010] for mountainous areas. The hydrological balance of the high-altitude watersheds is now more realistic. / On cherche souvent Ă Ă©tablir la distribution spatiale des prĂ©cipitations sur une grille rĂ©guliĂšre. Les mĂ©thodes d'interpolation spatiale sont couramment utilisĂ©es pour estimer de telle distribution Ă partir des observations au sol d'un rĂ©seau de mesures. Dans les rĂ©gions montagneuses, l'estimation des prĂ©cipitations en altitude reste un dĂ©fi et les rĂ©sultats des interpolations spatiales doivent ĂȘtre contrĂŽlĂ©s avec le maximum d'attention. Nous proposons dans cet article une mĂ©thodologie de validation d'un champ de prĂ©cipitation Ă trois niveaux successifs. Elle est appliquĂ©e dans le contexte d'une rĂ©gion semi-aride montagneuse, le Norte Chico au Chili (26°S-32°S). L'application de cette mĂ©thodologie a permis de mettre en Ă©vidence les bĂ©nĂ©fices apportĂ©s par une mĂ©thode d'interpolation dĂ©veloppĂ©e par ValĂ©ry [1] pour les zones de montagne. En particulier, le bilan hydrologique des bassins versants les plus en altitude est rendu plus vraisemblable
Are hydrologic-hydraulic coupling approaches able to reproduce Alex flash-flood dynamics and impacts on southeastern French headwaters?
International audienc
Incertitudes climatiques et hydrologiques sur les projections de crues et d'Ă©tiages en France
[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAUInternational audienceChanges in river flows are associated with different types of uncertainties, due to an imperfect knowledge of both future climate and rainfall-runoff processes. Due to computational constraints, impact and adaptation studies unfortunately cannot always afford to perform a detailed analysis of all these uncertainties. In that case, the modelling efforts have to focus on the most relevant source of uncertainty in order to provide the best estimate of the overall uncertainty. As part of the national Explore2070 project, the present study thus aims at assessing the hierarchy of uncertainties in changes on river flow extremes at the scale of France. Amongst all possible sources of uncertainties, two are here considered: (1) the uncertainty in General Circulation Model (GCM) configuration, with 7 different models that adequately sample the range of changes as projected by the GCMs used in the IPCC AR4 over France, and (2) the uncertainty in hydrological model structure, with 2 quite different models: GR4J (Perrin et al., 2003), a lumped conceptual model, and Isba-Modcou (Habets et al., 2008), a suite of a land surface scheme and a distributed hydrogeological model. The hydrological models have been run at more than 1500 locations in France over the 1961-1990 baseline period with forcings from both the Safran near-surface atmospheric reanalysis (Vidal et al., 2010) and the GCM control runs downscaled with a weather type method (Boé et al., 2006), and over the 2046-2065 period with forcings from all downscaled GCM runs under the A1B emissions scenario. Various high flow indices (annual maximum daily flow with return period of 10 and 20 years, the daily flow value exceeded 10% of the time) and low flow indices (annual minimum monthly flow with a 5-year return period, annual minimum 10-day mean flow with a 2-year return period, the daily flow value exceeded 95% of the time) as well as seasonality indices have been computed for both periods. An analysis of variance has been performed for each river flow index and at all stations shared by the two hydrological models (around 500) in order to assess the two considered sources of uncertainties in index changes as well as their hierarchy. Results first show spatial differences in the amount of sampled uncertainties due to both sub-regional climate specificities and catchment properties. The analysis of hierarchy between climate and hydrological uncertainties show striking differences (1) over France for a single index and (2) between different indices. The part of uncertainty relative to the hydrological response for example appears to be much more important for low-flow indices than for high-flow indices. Experiments have additionally been performed to possibly reduce the overall uncertainty by weighting combinations of GCM and hydrological model through their ability of reproducing observed river flow extreme values over the baseline period. The results of this study will help to define the relevant hydrological scenarios to be used in the adaptation part of the Explore2070 project for deriving national-scale adaptation strategies