Sediment transport applications in irrigation canals

Abstract

Sediment transport in irrigation canals is an important issue in the design and operation of irrigation systems. Frequently observed problems in irrigation systems are, for example, clogging of turnouts and reduction of the conveyance capacity of canals by siltation, and instability of side slopes and of structures due to erosion. Each year large investments are required to maintain or to rehabilitate these systems and to keep them in an acceptable condition for irrigation purposes.Irrigation canals are generally designed based on the assumption of uniform and steady flow of water and sediments. However, the flow is predominantly non-uniform, due to time-dependent discharges and constant water levels at regulation and division points. A strong relationship exists between the sediment transport and flow conditions.The aim of this article is to present some new developments in the behaviour of sediment and associated sediment transport in irrigation canals under changing flow conditions, as well as the deposition and/or entrainment rate in time and place for various flow conditions and sediment inputs. This article will discuss an approach to compute sediment transport in irrigation canals under non-uniform flow conditions. The sediment transport has been analysed for the flow conditions that prevail in irrigation canals. The Ackers-White and Brownlie equations are recommended to compute the sediment transport under equilibrium conditions for prismatic canal cross-sections.

Sediment transport problems in Nepal evaluated by the SETRIC model

“…Galappatti's model is based on the 2-D convection-diffusion equation. The mass balance equation for the total sediment transport is solved by the modified Lax method, assuming a steady condition of sediment concentration (Mendez, 1998;Depeweg and Mendez, 2002).…”

“…For details of the model, reference is made to the article by Depeweg and Mendez (2002). The main aim of the model is to evaluate the effects of sediment transport in irrigation canals under: changes in discharge; changes in incoming sediment load; controlled sediment deposition; sediment transport predictors; flow control structures; maintenance activities; operation activities.…”

“…The canal design approach and the proposed water delivery plan of one of the irrigation systems in Nepal were evaluated with the SETRIC model (Mendez, 1998;Depeweg and Mendez, 2002), which offers the possibility of predicting the behaviour of sediment in irrigation canals in time and space for specific flow conditions and incoming sediment load. The main aim of the article is to describe some new extensions of SETRIC and to show the capabilities of the model, which include the possibilities of evaluating the effect of structures and their operation on sediment transport behaviour.…”

Evaluation Of The Procedure To Design Irrigation Canals With Sediment-Laden Water By The Rational Method

“…SETRIC can be used to evaluate designs of irrigation networks and to analyse alternatives, but it can also be used as a decision support tool for the operation and maintenance of a system and/or to determine the efficiency of sediment removal facilities in an irrigation system (Depeweg and Néstor Méndez, 2002, Depeweg and Paudel, 2003, Depeweg and Rocabado Urquieta, 2004. Paudel (2010 used the model for a detailed analysis of field data and updated the design processes.…”

Use of modelling for the renovation of drainage channels – The case of the Bouteldja plain in northeastern Algeria

“…The proper management of sediments in the canal system is one of the major challenges of the improvement work, with a large part of the available maintenance and construction budget being spent annually on the removal of deposited sediments [DEPEWEG, MENDEZ 2002], so before undertaking the rehabilitation work on the drainage system, it is important to determine the effectiveness of the old system, the control of surface flows and more specifically the morphological evolution of the channel bottoms by sedimentation and their influence on flow during floods and consequently on agricultural land flooding BRICE [1998]. Several studies have been realised on flow and sedimentation in watersheds and dams such as ACHITE and MEDDI [2004], BESSENASSE [2010], BĄK and DĄBKOWSKI [2013] and REMINI and BENSAFIA [2015] and others studied in canals such as our case like [LIN 1993;MALATERRE et al 2013;MALAVOI et al 2011;OCHIERE et al 2015;SONG et al 2018;TERFOUS et al 2001].…”