The objective is to assess the causes of exceptional floods in the Ouémé basin using the HEC-RAS model. The results of the calculation made it possible to characterize: the losses and damage due to human settlement on the banks and agricultural production in the flood zone, the flooded extent and the height of submersion depend on the return period, most of the Flood waters converge towards the west of the basin (low risk) and towards the east around the Damè-Wogon depression (high risk).

Our multidisciplinary study reveals an alarming trend of beach retreat reaching −20 m ± 0.15 m yr⁻¹ after the human-induced change over the hydrological network where ~ 50 % of sediment discharge has been trapped upstream the dams. Accros the semi arid north African coasts, the rapid shoreline retreat is due to the decreasing of sediment fluvial discharge trapped by the dam infrastrcture.

The FRIEND-Water program (FWP) is the oldest and the most transverse program within the UNESCO IHP. It allows large communities of hydrologists to collaborate across borders on common shared data and scientific topics, addressed through 8 large world regions. Research priorities evolve according to the projections given by the member States during the IHP councils. FWP further activities follow the IHP IX program with the support of the Montpellier UNESCO Category II Center ICIREWAD.

The objective of this article is to assess recent trends of hydroclimatic quantities in Ogooue basin in the context of climate change. For this, the rainfall and discharges data of this basin were analyzed using the Pettitt test. The results of this study reveal a statistically significant decrease in runoff that the Pettitt test situates in 1972–73, but nothing like that for rainfall at this same time scale.

La sécheresse observée en Afrique tropicale vers la fin des années 1960, a également affecté le bassin de la Bénoué en Afrique centrale, avec une persistance remarquable qui s’est répercutée sur les écoulements. Les ruptures à la baisse ont été mises en évidence dans les séries hydropluviométriques de ce bassin au pas de temps annuel en 1970–71 (pluies) et 1971–72 (débits). Les déficits associés à cette rupture sont de −2,9 % pour les pluies et −14,2 % pour les débits.

This paper investigates links between rainfall variability in the Ogooué River Basin (ORB) and El Niño Southern Oscillation (ENSO) in the Pacific Ocean. Recent hydroclimatology studies of the ORB and surrounding areas resulting in contrasting conclusions about links between rainfall variability and ENSO. Then, this work uses cross-wavelet and wavelet coherence analysis to highlight significant links between ENSO and rainfall in the ORB.

This short paper is the preface of the PIAHS volume of the IAHS/UNESCO FRIEND-Water conference of Cotonou in November 2021.

Le district de Djibouti est situé dans le bassin versant de l’Oued Ambouli qui par sa nappe aquifère procure la source principale d’alimentation en eau potable de la ville de Djibouti, mais est aussi à l’origine de crues rares et brèves avec de lourds bilans humains et économiques Le développement du district se traduit par une expansion urbaine et un développement des activités qui accentuent le risque inondation.

This dataset provides a set of hydrometric indices for about 1500 stations across Africa with daily discharge data. These indices represent mean flow characteristics and extremes (low flows and floods), allowing us to study the long-term evolution of hydrology in Africa and support the modeling efforts that aim at reducing the vulnerability of African countries to hydro-climatic variability.

Wave-transported boulders are important records for storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information. We investigated the potential of a new dating technique, luminescence rock surface exposure dating, for estimating transport ages of wave-emplaced boulders. Our results indicate that the new approach may provide chronological information on decadal to millennial timescales for boulders not datable by any other method so far.

The downward of rainfall trend occurred in the study area in 1972, affecting a few coastal stations. In 1976, this decline extended to the South West and throughout the coastal region. In 1980, the drop covered the entire basin. This decline has resulted in an estimated deficit of 30 % on average in the eastern region, the coastal region and the Mina. However, the central part of the basin experienced a 20 % decrease compared to the period before the break (1968–1980).

The 8th Global FRIEND conference highlighted the advance in hydrological science and innovation in water management. 52 accepted papers cover study areas in precipitation and climate impact; observation, analysis and simulations of hydrologic processes; floods in the changing environments; drought monitoring and analysis; water resources and environmental impacts. The outcome of the conference presented in the proceedings will be shared and discussed widely among UNESCO IHP networks.

This study was designed to prove that the coastal changes of the Gulf of Tunis are mainly driven by the changes of the hydrological regime of the Medjerda river due to dams. We sampled cores of sediments in the low valley just before the sea, and analyzed them. They show the dramatic reduction of sediment supply after 1981, date of construction of the largest dam of Sidi Salem, and the disappearance of sand in the fluvial sediments.

The study investigates trends in mean and extreme rainfall, run-off, temperature and their relationship with large-scale atmospheric circulation. It focuses on two Moroccan watersheds; Bouregreg and Tensift, using data from 1977 to 2003. Results do not show a homogeneous behaviour in the catchments; the influence of the large-scale atmospheric circulation is different and a clear spatial dependence of the trend analysis is linked to the distance from the coast and the mountains.

Cette étude vise à analyser les tendances des pluies extrêmes dans un bassin semi-aride du Nord de l’Algérie et leur relation avec les types de circulation atmosphérique. Les pluies totales et l’intensité journalière ont connu une baisse significative durant la période 1971-2010 montre des tandis que leur fréquence ne montre pas de changement significatif. L’oscillation méditerranéenne est le type de circulation qui influence la variabilité des pluies extrêmes du bassin du Chéliff