- ItemOpen Access100 key questions to guide hydropeaking research and policy(Elsevier, 2023-09-16) Hayes, Daniel S.; Bruno, M.C.; Alp, Maria; Boavida, Isabel; Batalla, Ramon J.; Bejarano, Maria Dolores; Noack, Markus; Vanzo, Davide; Casas Mulet, Roser; Vericat Querol, Damià; Carolli, Mauro; Tonolla, Diego; Halleraker, Jo Halvard; Gosselin, M. P.; Chiogna, Gabriele; Zolezzi, Guido; Venus, TereseAs the share of renewable energy grows worldwide, flexible energy production from peak-operating hydropower and the phenomenon of hydropeaking have received increasing attention. In this study, we collected open research questions from 220 experts in river science, practice, and policy across the globe using an online survey available in six languages related to hydropeaking. We used a systematic method of determining expert consensus (Delphi method) to identify 100 high-priority questions related to the following thematic fields: (a) hydrology, (b) physico-chemical properties of water, (c) river morphology and sediment dynamics, (d) ecology and biology, (e) socio-economic topics, (f) energy markets, (g) policy and regulation, and (h) management and mitigation measures. The consensus list of high-priority questions shall inform and guide researchers in focusing their efforts to foster a better science-policy interface, thereby improving the sustainability of peak-operating hydropower in a variety of settings. We find that there is already a strong understanding of the ecological impact of hydropeaking and efficient mitigation techniques to support sustainable hydropower. Yet, a disconnect remains in its policy and management implementation.
- ItemOpen AccessA Finite element method integrated with Terzaghi's principle to estimate settlement of a building due to tunnel construction(MDPI, 2023-05-20) Rodríguez González, César Antonio; Rodríguez-Pérez, Ángel M.; López Alonso, Raúl; Hernández-Torres, Jose Antonio; Caparrós-Mancera, Julio JoseThis study presents the application of the finite element method integrated with Terzaghi's principle. The definition of a model in oedometric or confinement conditions for settlement estimation of a building after the construction of a tunnel, including the effect of Terzaghi's principle, is an unresolved problem. The objectives of this work include the demonstration of the need for a minimum of three methodological states to estimate said settlement. For this, a specific methodology is applied to a case study, with eight load steps and four types of coarse-grained soils. In the studied case, two layers of 50 m and 5 m with different degrees of saturation are overlaying an assumed impermeable rock layer. The excavation of a tunnel of 15 m in diameter at a depth of 30 m with drainage lining inside the tunnel is assumed. The minimum distance from the tunnel's outline to the mat foundation is 15.8 m. It is determined that the settlement, according to Terzaghi's principle, is around 11% of the total settlement for the most compacted soil types, reaching 35% for the loose soil type, from the tunnel's outline. In the mat foundation, it implies an increase in the differential settlement of up to 12%. It shows a nonlinear relationship between some of the variables in the analysis. To detect the collapse due to uplifting the tunnel invert, it was determined that it was not appropriate to model in oedometric conditions. The novelty of the investigation relies on identifying and determining the need for a minimum of three states for methodological purposes for a proper quantification of the total settlement: (i) before the construction of the tunnel, (ii) immediately after the excavation of the tunnel, but without groundwater inflow into the tunnel, and (iii) after the tunnelling, with stabilised groundwater inflow into the tunnel.
- ItemOpen AccessReconstrucción post-evento del flash-flood del 1 de septiembre de 2021 en Les Cases d’Alcanar (Tarragona)(Universitat Politècnica de València, 2023) Balasch Solanes, J. Carles (Josep Carles); Calvet, Jaume; Tuset Mestre, JordiLa crecida que se produjo el 1 de septiembre de 2021 en Les Cases d’Alcanar (Tarragona), es una de las de mayor magnitud del litoral mediterráneo occidental durante la época instrumental. Se ha realizado una reconstrucción post-evento determinando el caudal punta mediante el modelo hidráulico 2D IBER y la respuesta hidrológica de la cuenca a través del software hidrológico global HEC-HMS. Tras una lluvia de 251.9 mm en unas 3 horas, se estima que el pico fue de 159 m3·s-1 a la entrada de la población y el volumen de escorrentía fue de 1.15 hm3. El coeficiente de escorrentía alcanzó un valor de 0.76. Gran parte del desbordamiento en el núcleo poblado fue debido a la oclusión de los drenajes transversales al barranco y a la falta de capacidad de drenaje del canal. Los datos reconstruidos se consideran de un gran valor para la planificación de estructuras en cuencas pequeñas que carecen de datos de aforo.
- ItemOpen AccessSensitivity analysis in mean annual sediment yield modeling with respect to rainfall probability distribution functions(MDPI, 2023-01) Rodríguez González, César Antonio; Rodríguez-Pérez, Ángel Mariano; López Alonso, Raúl; Hernández-Torres, Jose Antonio; Caparrós-Mancera, Julio JoseAn accurate estimation of the mean annual sediment yield from basins contributes to optimizing water resources planning and management. More specifically, both reservoir sedimentation and the damage caused to infrastructures fall within its field of application. Through a simple probabilistic combination function implemented in hydrometeorological models, this sediment yield can be estimated on a planning and management scale for ungauged basins. This probabilistic combination methodology requires the use of probability distribution functions to model design storms. Within these functions, SQRT-ET max and log-Pearson type III are currently highlighted in applied hydrology. Although the Gumbel distribution is also relevant, its use has progressively declined, as it has been considered to underestimate precipitation depth and flow discharge for high return periods, compared to the SQRT-ET max and log-Pearson III functions. The quantification of sediment yield through hydrometeorological models will ultimately be affected by the choice of the probability distribution function. The following four different functions were studied: Gumbel type I with a small sample size, Gumbel type I with a large sample size, log-Pearson type III and SQRT-ET max. To illustrate this, the model with these four functions has been applied in the Alto Palmones basin (South Iberian Peninsula). In this paper, it is shown that the application of Gumbel function type I with a small sample size, for the estimation of the mean annual sediment yield, provides values on the conservative side, with respect to the SQRT-ET max and log-Pearson type III functions.
- ItemOpen AccessLong-term geomorphic adjustments following the recoupling of a tributary to its main-stem river(Elsevier, 2023) Blackburn, Joel; Marteau, Baptiste; Vericat Querol, Damià; Batalla, Ramon J.; Comte, Jean-Christophe; Gibbins, ChristopherRiver restoration and rehabilitation projects are widespread, but rarely include the data needed to fully evaluate if they are successful in achieving their goals or how long the process of readjustment takes before a new ‘recovered’ regime state is reached. Here we present a seven-year post-project dataset detailing the morpho-sedimentary responses of a river to the reconnection of a formerly diverted tributary, and relate observed changes to conditions in the river prior to the reconnection. We describe changes in the tributary and main-stem channels, including changes in channel planform, morphology, and the export of coarse and fine sediment from the tributary to the main-stem river. We use the data to develop a conceptual model of the system's response to the reconnection. Marked geomorphic changes occurred within the first two years after the reconnection. Changes during this ‘shock phase’ included dramatic erosion and subsequent deepening and widening of the tributary channel, rapid development of a confluence bar and an increase in fine sediment delivered to the main-stem. After this shock phase, and despite the continued occurrence of high magnitude flow events, the rate of geomorphic change in the tributary began to decrease, and the rate of growth of the confluence bar slowed. Fine sediment volumes in the main-stem also decreased steadily. After an adjustment phase lasting a total of approximately 4.5 yr (including the initial 2-yr shock phase), the tributary to mainstem system appeared to reach a new dynamic equilibrium that we consider the adjusted regime state. This new regime state was characterised by, among other things, an increase in geomorphic heterogeneity in the tributary and main-stem channels. Changes in both fluvial processes and forms indicate that within 4.5 yr the project was successful in achieving its goal of augmenting sediment and increasing geomorphic heterogeneity. Our conceptual model of adjustment mirrors that developed by Petts and Gurnell (2005), with the river passing through a complex and dynamic adjustment phase before reaching a new regime state. However, unlike the responses to impoundment represented by Petts and Gurnell, our model of river response to rehabilitation charts increases in dynamism and heterogeneity.