Caractérisation des saisons de pluies au Burkina Faso dans un contexte de changement climatique et évaluation des impacts hydrologiques sur le bassin du Nakanbé PDF Download
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Author: Boubacar Ibrahim Publisher: ISBN: Category : Languages : en Pages : 236
Book Description
This study aims to a description of the variability in the rainfall regime over the West African Sahel and an assessment of the impacts of this variability on the water resources in the region from a set of some hydrological models. Although, many results of some studies on rainfall variability over Sahel during the last five decades (1961-2009) show a significant decrease in the annual rainfall amount since 1970. This rainfall deficit has entailed a severe hydric stress in the region. Burkina Faso, a sahelian country, is under this situation of continuous drought condition. So, to characterize the climate condition at the scale of Burkina Faso, we analyzed the rainfall data of the synoptic network through a discretization of the rainy seasons in several characteristics relative to the season period, rainfall frequency and intensity, and the dry spells. A computation of these characteristics from observed rainfall data and from simulated rainfall data of five regional climate models (CCLM, HadRM3P, RACMO, RCA et REMO) run under scenario A1B of IPCC, helped to assess the representativeness of the simulations over Burkina Faso. Indeed, the simulated rainfall data present high frequency of low rainfalls (between 0.1 mm/day and 5 mm/day), and some heavy maximum daily rainfall. However, an application of a correction procedure, quantile-quantile, to the simulated rainfall, significantly reduced the different biases and produced some rainfall data similar to the observations over the 1961-2009 period. An analysis of the future variability of rainfall regime over the prediction period of 2021-2050 in comparison to the reference period of 1971-2000 and from the five climate models presents different tendencies in the evolution of the annual rainfall amount: two models predict significant decrease in rainfall while two others predict a significant increase in the annual rainfall amount. These significant changes come from a decrease in rainfall frequency or an increase in rainfall intensity. However, two consensuses come out from the models: a decrease in the very low rainfall (0.1 à 5 mm/jr) and a lengthening of the mean dry spell. Also, four models show an increase in the very strong rainfall (>50 mm/day). On the other hand, the five models show an increasing trend in the potential evapotranspiration (PET) over the 1961-2050 period. The impacts of these changes in rainfall regime and the increase in the PET on the hydrological regime of the sahelian part of Nakanbé basin in Burkina Faso (upstream of the Wayen gauge) are assessed from two hydrological models, GR2M and ORCHIDEE. The GR2M, calibrated and validated for the basin over the 1978-1999 period, reproduced the hydrological balance of the basin during this period. But for ORCHIDEE, a repartition procedure was elaborated in order to distribute the simulated runoff into the discharges and infiltrations. So, an implementation of these hydrological models under the climate change conditions of rainfall decrease shows an hydrological constraint with a decrease in the runoff and the water table recharge, and an increase in the evaporation rate in the hydrological balance of the basin. However, the amplitude of the hydrological impacts depends on the type of the change in the main characteristics of the rainy season: in the rainfall frequency or in the rainfall intensity. So, a decrease in the rainfall intensity is more prejudicial to water resources availability with an important increase in the evaporation rate and an important decrease in the runoff and in the groundwater recharge.
Author: Boubacar Ibrahim Publisher: ISBN: Category : Languages : en Pages : 236
Book Description
This study aims to a description of the variability in the rainfall regime over the West African Sahel and an assessment of the impacts of this variability on the water resources in the region from a set of some hydrological models. Although, many results of some studies on rainfall variability over Sahel during the last five decades (1961-2009) show a significant decrease in the annual rainfall amount since 1970. This rainfall deficit has entailed a severe hydric stress in the region. Burkina Faso, a sahelian country, is under this situation of continuous drought condition. So, to characterize the climate condition at the scale of Burkina Faso, we analyzed the rainfall data of the synoptic network through a discretization of the rainy seasons in several characteristics relative to the season period, rainfall frequency and intensity, and the dry spells. A computation of these characteristics from observed rainfall data and from simulated rainfall data of five regional climate models (CCLM, HadRM3P, RACMO, RCA et REMO) run under scenario A1B of IPCC, helped to assess the representativeness of the simulations over Burkina Faso. Indeed, the simulated rainfall data present high frequency of low rainfalls (between 0.1 mm/day and 5 mm/day), and some heavy maximum daily rainfall. However, an application of a correction procedure, quantile-quantile, to the simulated rainfall, significantly reduced the different biases and produced some rainfall data similar to the observations over the 1961-2009 period. An analysis of the future variability of rainfall regime over the prediction period of 2021-2050 in comparison to the reference period of 1971-2000 and from the five climate models presents different tendencies in the evolution of the annual rainfall amount: two models predict significant decrease in rainfall while two others predict a significant increase in the annual rainfall amount. These significant changes come from a decrease in rainfall frequency or an increase in rainfall intensity. However, two consensuses come out from the models: a decrease in the very low rainfall (0.1 à 5 mm/jr) and a lengthening of the mean dry spell. Also, four models show an increase in the very strong rainfall (>50 mm/day). On the other hand, the five models show an increasing trend in the potential evapotranspiration (PET) over the 1961-2050 period. The impacts of these changes in rainfall regime and the increase in the PET on the hydrological regime of the sahelian part of Nakanbé basin in Burkina Faso (upstream of the Wayen gauge) are assessed from two hydrological models, GR2M and ORCHIDEE. The GR2M, calibrated and validated for the basin over the 1978-1999 period, reproduced the hydrological balance of the basin during this period. But for ORCHIDEE, a repartition procedure was elaborated in order to distribute the simulated runoff into the discharges and infiltrations. So, an implementation of these hydrological models under the climate change conditions of rainfall decrease shows an hydrological constraint with a decrease in the runoff and the water table recharge, and an increase in the evaporation rate in the hydrological balance of the basin. However, the amplitude of the hydrological impacts depends on the type of the change in the main characteristics of the rainy season: in the rainfall frequency or in the rainfall intensity. So, a decrease in the rainfall intensity is more prejudicial to water resources availability with an important increase in the evaporation rate and an important decrease in the runoff and in the groundwater recharge.
Author: Boubacar Ibrahim Publisher: Presses Academiques Francophones ISBN: 9783838189987 Category : Languages : fr Pages : 380
Book Description
Resume: La region sahelienne de l'Afrique de l'Ouest est soumise a une situation de deficit pluviometrique sur plus de quatre decennies. Ainsi, le Burkina Faso, pays situe au c ur de la region n'echappe pas a ces conditions climatiques difficiles. Cette situation a entraine une forte sollicitation des ressources en eau de surface dans la partie centrale du pays pour la satisfaction des differents besoins de la population. D'ou, le changement climatique futur suscite beaucoup d'interrogations sur la disponibilite de ces ressources en eau au cours des decennies a venir. Dans cette etude nous avons analyse les reponses hydrologiques du bassin de Nakanbe (un bassin qui couvre la partie centrale du pays et qui heberge plus de 400 retenues d'eau) aux differents changements du climat predits par des modeles climatiques regionaux tournes sous le scenario intermediaire A1B de l'IPCC. L'etude montre que les impacts hydrologiques des differents changements simules et selon deux modeles hydrologiques (GR2M et ORCHIDEE) valides sur le bassin dependent de l'amplitude des modifications dans la structure des saisons de pluies (frequence et intensite des pluies).
Book Description
Ce livre décrit les processus hydrologiques et leurs dynamiques passées et actuelles au gré de l’évolution des agrosystèmes, de leur emprise spatiale, de leur capacité d’adaptation au changement global, et aux changements climatiques. Il se fonde sur l’indicateur que représente la capacité de rétention en eau des sols, qui conditionne la bonne alimentation en eau et en nutriments des systèmes racinaires, tant des cultures que de la végétation naturelle. C’est aussi cette rétention en eau qui permet de limiter le ruissellement et les inondations en aval. Parti d’une réflexion sur le paradoxe hydrologique du Sahel (la hausse des écoulements observée dans cette région durant la sécheresse), l’ouvrage décrit les enjeux de ces évolutions spatio-temporelles et entend montrer que la pression démographique n’est pas forcément un facteur de dégradation des agrosystèmes; au contraire, les régions les plus densément peuplées à l’heure actuelle sont très souvent celles qui font preuve de la plus grande capacité de résilience et d’adaptation aux changements climatiques et environnementaux.
Book Description
Le Nord-Ouest Algérien figure parmi les zones les plus sensibles aux variabilités et changements climatiques, dont la baisse de précipitations a été marquée le long du Nord de l'Afrique. Une mise en place du modèle conceptuel semi-distribué SWAT avec une calibration et une validation sur une période de vingt neuf ans (1981-1995 pour la calibration et 1996-2010 pour la validation) est effectuée au niveau du bassin versant de la Tafna. L'utilisation et l'évaluation de la performance des méthodes de correction du biais des modèles climatiques régionaux du projet Cordex-Africa, et leur impact sur l'hydrologie pendant la période de référence a fait l'objet de tout un chapitre afin d'étudier les changements climatiques et leurs impacts sur le cycle hydrologique pendant la période future 2020-2099 au niveau la région étudiée. Les tendances les plus significatives ont été marquées pour les baisses de précipitations tout au long du 21ème siècle. Ces baisses ont influencé toutes les composantes du cycle hydrologique du débit des cours d'eau jusqu'à l'évapotranspiration. Le modèle SWAT nous a permis de représenter à l'échelle temporelle ainsi que spatiale la distribution des différentes composantes hydrologiques, débits des cours d'eau, ruissellement en tout point des sous-bassins versants, les précipitations, l'écoulement latéral, la teneur en eau dans le sol, et l'évapotranspiration pendant la période de référence et les tendances de changements pendant les périodes futures étudiées dans ce travail. Ces résultats nous ont permis de définir l'impact des diminutions des pluies sur ces composantes hydrologiques durant les deux mois traités dans cette étude Janvier et Juillet, ainsi que de constater la distribution, les tendances et les interactions de l'ensemble des mois de l'année. Les composantes hydrologiques (ruissellement, évapotranspiration...etc.) sont impactés par la baisse des pluies durant la période future d'environs -35%, cet impact est visible, pendant les mois humides avec une baisse du débit des cours d'eau et de la teneur en eau dans le sol variant autours de -40% et l'écoulement latéral ainsi que l'évapotranspiration d'environ -30%. Toutefois, la surestimation des pluies sur les projections des RCMs pendant la période estivale a inversé la tendance vers une augmentation des pluies ainsi que les composantes hydrologiques. Afin d'avoir une vue générale sur les résultats des tendances obtenues dans cette étude, nous avons évalué le degré de sécheresse à l'aide d'indices de sécheresse standardisés, en utilisant certaines composantes telles que la pluie, l'évapotranspiration et le ruissellement. Ces indices utilisés nous ont permis d'attribuer une estimation de sécheresse comprise entre modérée à forte à moyen et long terme, pour le bassin versant de la Tafna.
Author: Zied Haj-Amor Publisher: CRC Press ISBN: 100076849X Category : Law Languages : en Pages : 196
Book Description
Climate Change Impacts on Coastal Soil and Water Management discusses the latest approaches for monitoring soil and water degradation in coastal regions under current climate conditions as well as potential further changes in the future. It presents an overview of climate change impacts on soil and water resources and summarizes the adaptation of practical options and strategies to minimize the potential risks, such as land degradation, seawater intrusion, droughts, ocean acidification, etc. The book aims to promote the adoption of best practices, which can be selected and implemented according to the respective local conditions. In addition, the recommendations for specific soil and water use planning strategies to address climate change can also be incorporated into national and international development plans. Features: • Presents the general properties and analysis of soil and water resource conditions for coastal regions • Offers practical advice for adapting to climate change through case studies from diverse coastal settings around the globe • Presents information in an accessible format for practitioners in soil and water sciences, as well as for those working in related disciplines • Includes end-of-chapter summaries and homework problems Written primarily for practicing soil, water, agricultural, and environmental scientists, this book provides the latest research on soil and water resources management, soil processes and properties, and the related effects of climate change. It assesses the effectiveness of the methods currently in use and under future climate change scenarios as well.
Author: Aondover Tarhule Publisher: BoD – Books on Demand ISBN: 9535111876 Category : Science Languages : en Pages : 218
Book Description
As societies transition to evidence-based adaptation and management there is increasing recognition of the need for understanding climate change and variability dynamics and impacts at regional levels and for various activities. This book is a contribution toward that goal. Readers interested in climate change management will find detailed discussions of climatic variability dynamics in selected regions as well as new innovative ways of monitoring climate change, assessing climate risks, and predicting impacts. Those interested in refreshing the fundamentals of climate change and climate variability will find a very accessible review of the status of knowledge on the subject, including a balanced interrogation of available evidence. In an attempt to keep the book accessible, every effort was made to minimize technical jargon without compromising scientific accuracy. The result should be useful to researchers, practitioners, and policy makers.
Author: Boubacar Ibrahim
Author: Boubacar Ibrahim
Author: Boubacar Ibrahim
Author: Olivier Overney
Author: Luc Descroix
Author: Amina Mami
Author: Isabelle La Jeunesse
Author: Thorsten Wagener
Author: Zied Haj-Amor
Author: Stewart Franks
Author: Aondover Tarhule