Analyse De La Variabilite Hydroclimatique Et Impacts Des Barrages Sur Le Regime Hydrologique D’une Riviere De Zone Semi-Aride : Le Sebou Au Maroc

Abstract

The analysis and characterization of hydroclimatic variability over a long period of time is fundamental for understanding the impacts of climate change and vulnerability of hydrological regimes. The present work is a study of the spatial and temporal variability of the climatic and hydrological series in the Sebou river basin (Morocco) over the past sixty years using Hanning low-pass filter of second order and statistical tests of stationarity of climate and hydrological time series. These statistic testing methods were applied to analyze the spatial and temporal evolution to the hydroclimatologic data of the AzibEsSoltane, M'jara and MechraBelKsiri hydrometric stations, which are, respectively, located in the Middle Sebou, the Ouerrha Tributary of the Sebou and the Low Sebou. This analysis shows that climate variability has resulted particularly in strong interannual fluctuations in rainfall reflected by a succession of dry and wet periods between 1939 and 1979 and a general decrease in precipitation since 1980. The Water flow time series analysis are marked by ruptures detected mainly between 1972 and 1978 reflecting rainoff declines of about 50% in the Sebou downstream and 70% in the middle Sebou. Several decreases in water discharge (up to 90%) were also detected in the Ouerrhariver since 1996, when the Al Wahda dam started operating.The analysis of the relationships between rainfall and water discharge shows that the impacts of dams constructions are stronger than the climatic effect in the Ouerrha river.

Erosion fluviale et mutations morphométriques du drainage dans le secteur aval du barrage de Lagdo (Bassin de la Bénoué, Nord-Cameroun)

“…L'évolution morphométrique du drainage est une réalité courante à tous les cours d'eau, surtout en contexte de modification des paramètres d'écoulement. En effet, les ouvrages hydrauliques ont souvent eu pour effet de perturber les évolutions naturelles, soit en les limitant ou en déclenchant des processus parfois accélés (Dzana, 2000 ;Aubry, 2012 ;Amassou et al, 2012 ;Bahin et al, 2017 ;Mbélé Abbo, 2018 ;Nzango, 2018). Pour le cas d'espèce, l'analyse diachronique (1975 et 2016) du secteur aval de ce barrage révèle trois résultats importants.…”

“…Les facteurs d'évolution des systèmes érosifs fluviaux sont multiples. Il est en effet admis depuis le Néolithique que nos paysages sont une co-construction régie à la fois par les dynamiques environnementales et sociétales (Carcaud, 2016). Même si ces deux familles de facteurs restent poignantes, l'acception la plus admise de nos jours par l'ensemble des scientifiques est que ces dynamiques environnementales et sociétales sont de plus en plus accélérées, notamment à cause d'une fréquente variabilité du climat et d'un accroissement démographique toujours constant.…”

Climate Risks Assessment, Opportunities Related to the Evolution of Ecosystems and Limitation of the Provision of Ecosystem Services: Landscape Case of South-Kivu (Albertine Riflt, Drc)

“…Several environmental agreements recognize that the depletion of ecosystems limits the capacity to adapt to climate change and that ecosystem-based approaches (EbA) to adaptation should be a priority for states, as this approach has the potential to increase adaptive capacity and social and ecological resilience. It should be noted that very often these visions discussed in the climate negotiation rooms are not translated into concrete targets and hardly involve local communities 2 . This is why our research focuses on measures to increase the acceptance of the ecosystem-based approach (EbA) to adaptation in the DRC government's action plans in terms of expected contributions determined at the national level.…”

“…Climate change is a major global challenge, which is increasingly strong on the international scene. Scientific studies clearly show that the changes at work since the beginning of the industrial period are disproportionate to the natural variability of the climate [1], [2]. Since the United Nations Conference on Environment and Sustainable Development, known as the Rio Earth Summit in 1992 and the other various conventions on climate change (Kyoto Protocol in 1997, Paris Protocol 2015, Madrid Protocol 2019), decision-makers around the world have been made aware of the dangers of climate change worldwide.…”