A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools

Abstract

Abstract. There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes within restored gully reaches, despite it being a crucial issue for the design of gully restoration measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and damfilling conditions as well as a method of estimating efficiency in order to provide design guidelines. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump, impact flow, gradually varied flows). Ten main classifications of flow regimes were identified, producing similar results when compared with the IBER model. An interval for optimal energy dissipation (ODI) was observed when the steepness factor c was plotted against the design number (DN, ratio between the height and the product of slope and critical depth). The ODI was characterized by maximum energy dissipation and total influence conditions. Our findings support the hypothesis of a maximum flow resistance principle valid for a range of spacing rather than for a unique configuration. A value of c = 1 and DN ∼ 100 was found to economically meet the ODI conditions throughout the different sedimentation stages of the structure. When our model was applied using the same parameters to the range typical of step-pool systems, the predicted results fell within a similar region to that observed in field experiments. The conceptual model helps to explain the spacing frequency distribution as well as the often-cited trend to lower c for increasing slopes in step-pool systems. This reinforces the hypothesis of a close link between stable configurations of step-pool units and man-made interventions through check dams.

Computational Modeling of Fine Sediment Relocation Within a Dam Reservoir by Means of Artificial Flood Generation in a Reservoir Cascade

“…The reader is referred to Bladé, Cea, & Corestein, Escolano, et al (2014) and the references therein for a detailed description and experimental validation of the numerical schemes used to solve the shallow water equations, which are not included in this paper for brevity. This hydraulic module has been applied to several studies in the past, including the river inundation modeling, overland flow (Cea & Bladé, 2015), evaluation of gully restoration measures (C. Castillo et al, 2014), wood transport in rivers (Ruiz-Villanueva et al, 2014), and water quality loss (Cea et al, 2016).…”

Modelación Hidráulica 2D de Inundaciones en Regiones con Escasez de Datos. El Caso del Delta del Río Ranchería, Riohacha-Colombia

“…IBER 2D consta de diferentes módulos: turbulencia, transporte de sedimentos e hidrodinámica, constituyendo este último, la base de la herramienta empleando las ecuaciones de St. Venant 2D de aguas someras resueltas bajo el método de volúmenes finitos y sometidas al principio de conservación de la materia y de momento en las dos direcciones horizontales (Bladé et al, 2014). IBER 2D ha sido empleado en múltiples estudios de hidráulica aplicada: inundaciones fluviales (Bonasia et al, 2017), evaluación de medidas de restauración para pequeños cauces (Castillo et al, 2014), ruptura de represas (Álvarez et al, 2017) y transporte de material leñoso en ríos (Ruiz et al, 2015). Un input importante en IBER es la topografia a través de un MDT.…”

Experimental study of sediment traps permeable for frequent floods

“…Low clearance heights or narrow clearance widths of the opening(s) in the barrier may interrupt the river connectivity with 10 negative effects on the downstream eco-morphological river state (Brandt, 2000;Castillo et al, 2014;Kondolf, 1997). The functioning of barriers for both hydraulic and mechanical retention controls is experimentally examined in the present study.…”