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The risk related to embankment dam breaches needs to be evaluated in order to prepare emergency action plans. The physical and hydrodynamic parameters of the flood wave generated from the dam failure event correspond to various breach parameters, such as width, slope, and formation time. This study aimed to simulate the dam breach failure scenario of the Yabous dam (northeast Algeria) and analyze its influence on the related areas (urban and natural environments) downstream of the dam. The simulation was completed using the sensitivity analysis method to assess the impact of breach parameters and flooding on the dam break scenario. The flood wave propagation associated with the dam break was simulated using the one-dimensional HEC-RAS hydraulic model. This study applied a sensitivity analysis of three breach parameters (slope, width, and formation time) on five sites selected downstream of the embankment dam. The simulation showed that the maximum flow of the flood wave recorded at the level of the breach was 8768 m3/s, which gradually attenuated along the river course to reach 1972.7 m3/s at about 8.5 km downstream the dam. This study established the map of flood risk areas that illustrated zones threatened by the flooding wave triggered by the dam failure due to extreme rainfall events. The sensitivity analysis showed that flood wave flow, height, and width revealed positive and similar changes for the increases in adjustments (±25% and ±50%) of breach width and slope in the five sites. However, flood wave parameters of breach formation time showed significant trends that changed in the opposite direction compared to breach slope and width. Meanwhile, the adjustments (±25% and ±50%) of the flood hydrograph did not significantly influence the flood parameters downstream of the dam. In the present study, the HEC-RAS 1-D modeling demonstrated effectiveness in simulating the propagation of flood waves downstream of the dam in the event of dam failure and highlighted the impact of the breach parameters and the flood hydrographical pattern on flood wave parameters.

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-Introduction. The aim of this work was to study the effects of regulated deficit irrigation (RDI) on fruit yield, fruit weight and fruit quality parameters, as well as soil-plant water relations, in apple orchards under highfrequency subsurface drip irrigation in a region with a continental climate. Materials and methods. Four irrigation treatments were applied in 2010 and 2011 to apple trees cv. 'Gala': T1, no irrigation; T2, optimal irrigation except during summer; T3, optimal irrigation except during summer when RDI with a threshold for irrigation at −1.2 MPa midday stem water potential (Ψ stem) was utilised; T4, optimal irrigation. The soil water status and plant water status were followed over two growing seasons. Results and discussion. The irrigation treatments had no significant impact on fruit yield. However, compared with optimal irrigation (T4) and RDI (T3), the absence of irrigation in summer (T1, T2) induced low Ψ stem (< −1.2 MPa), decreased fruit size and slightly increased the soluble solid, vitamin C and polyphenol contents of the fruits. The RDI (T3) during summer allowed a water-use reduction of 47% without loss in fruit yield, fruit weight and fruit quality compared with the optimal irrigation (T4). Conclusion. The RDI treatment saved 47% water compared with optimal irrigation without negative impacts on yield and fruit quality. In the temperate conditions of Switzerland, Ψ stem, as well as Ψ soil, are well adapted for scheduling RDI in apple orchards.Keywords: Switzerland / apple / Malus domestica / irrigation scheduling / regulated deficit irrigation / water stress / phenolics / vitamin C Résumé -Influence de stratégies d'irrigation sur la productivité, la qualité des fruits et le statut hydrique sol-plante de pommiers arrosés en goutte à goutte enterré. Introduction. Le but de cette étude a été d'analyser les effets de la régulation déficitaire de l'irrigation (RDI), avec des applications d'eau en goutte à goutte enterré à fréquence élevée, sur le rendement en fruits, le poids des fruits, et la qualité des fruits, ainsi que sur les relations hydriques entre sol et plante sur des vergers de pommier sous un climat continental. Matériel et méthodes. Quatre procédés d'irrigation ont été appliqués aux pommiers (cv. 'Gala') en 2010 et 2011 : T1, témoin non irrigué ; T2, irrigation optimal à l'exception d'absence d'irrigation durant l'été ; T3, irrigation optimal à l'exception une restriction d'irrigation induisant un stress modéré durant l'été, avec un seuil fixé à -1.2 MPa de Ψ stem (irrigation déficitaire régulée, RDI) ; T4, irrigation optimale. L'impact de ces régimes sur le potentiel hydrique du sol (Ψ soil) et le potentiel hydrique du tronc (Ψ stem) a été suivi pendant deux saisons. Résultats et discussion. Les régimes d'irrigation n'ont eu aucun impact significatif sur le rendement en fruits. Toutefois, par rapport à l'irrigation optimale (T4) et RDI (T3), l'absence d'irrigation en été (T1, T2) induit des potentiels de tronc bas (Ψ stem < -1,2 MPa) et une diminution du poids des ...

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