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In order to cover the crop water requirements, flow control structures such as gates and weirs are used to transfer the desired amount of water from the canals to the field canals. This paper examines the impact of gate operation and the selection of gates on the deposition of non-cohesive sediment. The Delft3D model is used to simulate the effects of different scenarios regarding gate operation and the location of the gate that is opened. The model results showed that the gate selection affects not only hydraulic parameters but also morphological parameters. It was found that opening the gates closer to the offtake resulted in less sediment deposition at the entrance of the branch canal when compared to opening the gates further away. Gate selection can be used as a tool in sediment management. By alternating the opening of different gates sediments that are already deposited after opening one gate can be eroded when another gate is operated, thus minimizing the additional cost of sediment removal. The use of Delft3D proved beneficial as the selection of different gates leads to asymmetric sediment deposition patterns which would be missed when using a 1D model.
Shaimaa Theol; Bert Jagers; Jigyasha Yangkhurung; F. Suryadi; Charlotte De Fraiture. Effect of Gate Selection on the Non-Cohesive Sedimentation in Irrigation Schemes. Water 2020, 12, 2765 .
AMA StyleShaimaa Theol, Bert Jagers, Jigyasha Yangkhurung, F. Suryadi, Charlotte De Fraiture. Effect of Gate Selection on the Non-Cohesive Sedimentation in Irrigation Schemes. Water. 2020; 12 (10):2765.
Chicago/Turabian StyleShaimaa Theol; Bert Jagers; Jigyasha Yangkhurung; F. Suryadi; Charlotte De Fraiture. 2020. "Effect of Gate Selection on the Non-Cohesive Sedimentation in Irrigation Schemes." Water 12, no. 10: 2765.
Sediments cause serious problems in irrigation systems, adversely affecting canal performance, driving up maintenance costs and, in extreme cases, threatening system sustainability. Multiple studies were done on the deposition of non-cohesive sediment and implications for canal design, the use of canal operation in handling sedimentation problems is relatively under-studied, particularly for cohesive sediments. In this manuscript, several scenarios regarding weirs and gate operation were tested, using the Delft3D model, applied to a case study from the Gezira scheme in Sudan. Findings show that weirs play a modest role in sedimentation patterns, where their location influences their effectiveness. On the contrary, gate operation plays a significant role in sedimentation patterns. Reduced gate openings may cause canal blockage while intermittently fully opening and closing of gates can reduce sediment deposition in the canal by 54% even under conditions of heavy sediment load. Proper location of weirs and proper adjusting of the branch canal’s gate can substantially reduce sedimentation problems while ensuring sufficient water delivery to crops. The use of 2D/3D models provides useful insights into spatial and temporal patterns of deposition and erosion but has challenges related to running time imposing a rather coarse modelling resolution to keep running times acceptable.
Shaimaa A. Theol; Bert Jagers; F. X. Suryadi; Charlotte De Fraiture. The Role of Gate Operation in Reducing Problems with Cohesive and Non-Cohesive Sediments in Irrigation Canals. Water 2019, 11, 2572 .
AMA StyleShaimaa A. Theol, Bert Jagers, F. X. Suryadi, Charlotte De Fraiture. The Role of Gate Operation in Reducing Problems with Cohesive and Non-Cohesive Sediments in Irrigation Canals. Water. 2019; 11 (12):2572.
Chicago/Turabian StyleShaimaa A. Theol; Bert Jagers; F. X. Suryadi; Charlotte De Fraiture. 2019. "The Role of Gate Operation in Reducing Problems with Cohesive and Non-Cohesive Sediments in Irrigation Canals." Water 11, no. 12: 2572.
Nearshore morphological modelling is challenging due to complex feedback betweenhydrodynamics, sediment transport and morphology bridging scales from seconds to years.Such modelling is, however, needed to assess long-term effects of changing climates on coastalenvironments, for example. Due to computational efficiency, the sediment transport driven bycurrents and waves often requires a parameterization of wave orbital velocities. A frequently usedparameterization of skewness-only was found to overfeed the coast unrealistically on a timescale ofyears—decades. To improve this, we implemented a recently developed parameterization accountingfor skewness and asymmetry in a morphodynamic model (Delft3D). The objective was to compare theeffects of parameterizations on long-term coastal morphodynamics. We performed simulations withdefault and calibrated sediment transport settings, for idealized coastlines, and compared the resultswith measured data from analogue natural systems. The skewness-asymmetry parameterization wasfound to predict overall stable coastlines within the measured envelope with wave-related calibrationfactors within a factor of 2. In contrast, the original parameterization required stronger calibration,which further affected the alongshore transport rates, and yet predicted erosion in deeper areas andunrealistic accretion near the shoreline. The skewness-asymmetry parameterization opens up thepossibility of more realistic long-term morphological modelling of complex coastal systems.
Marcio Boechat Albernaz; Gerben Ruessink; H. R. A. (Bert) Jagers; Maarten G. Kleinhans. Effects of Wave Orbital Velocity Parameterization on Nearshore Sediment Transport and Decadal Morphodynamics. Journal of Marine Science and Engineering 2019, 7, 188 .
AMA StyleMarcio Boechat Albernaz, Gerben Ruessink, H. R. A. (Bert) Jagers, Maarten G. Kleinhans. Effects of Wave Orbital Velocity Parameterization on Nearshore Sediment Transport and Decadal Morphodynamics. Journal of Marine Science and Engineering. 2019; 7 (6):188.
Chicago/Turabian StyleMarcio Boechat Albernaz; Gerben Ruessink; H. R. A. (Bert) Jagers; Maarten G. Kleinhans. 2019. "Effects of Wave Orbital Velocity Parameterization on Nearshore Sediment Transport and Decadal Morphodynamics." Journal of Marine Science and Engineering 7, no. 6: 188.
This paper presents a new model, using existing consolidation theory, suitable for long-term morphodynamic simulations; we refer to the dynamic equilibrium consolidation (DECON) model. This model is applicable for muddy systems at small suspended particulate matter (SPM) concentrations, where the sedimentation rates are smaller than the consolidation rates and small fractions of sand can be accounted for. Thus, the model assumes quasi-equilibrium of the consolidating bed. It is derived from the full consolidation (Gibson) equation and is implemented in a mixed Lagrangian-Eulerian bed model guaranteeing stable and non-negative solutions, while numeric diffusion remains small. The erosion and deposition of sand and mud is accounted for, whereas internal mixing (e.g., bioturbation) is modeled through diffusion. The parameter settings for the new consolidation model (the hydraulic conductivity, consolidation coefficient, and strength) can be obtained from consolidation experiments in the laboratory. The model reproduces one-dimensional consolidation experiments and the qualitative behavior of erosion and deposition in a tidal flume. The DECON model was also applied to more natural conditions, simulating fine sediment dynamics on a schematized mud flat and in a schematized tidal basin under tide and wave forcing. The computational results of the mudflat simulations compared well with the simulations with the full Gibson equation. For the tidal basin simulations, DECON predicted the expected landward tidal transport of fine sediment during tide-dominated conditions, while the tidal basin withstood erosion during the more energetic wave-dominated periods. Computational times for the morphodynamic simulations of the tidal basin example without waves increased by a factor of 5 when consolidation was included. For the simulations with waves, this increase in computational times was only a factor of 2, as simulations with waves are always expensive. Applying a complete consolidation model would be prohibitive. The DECON model therefore serves as a useful tool to simulate fine-sediment dynamics in complex wave- and tide-dominated conditions, as well as the effects of seasonal variations.
J. C. Winterwerp; Zeng Zhou; G. Battista; T. Van Kessel; H. R. A. Jagers; D. S. Van Maren; M. Van Der Wegen. Efficient Consolidation Model for Morphodynamic Simulations in Low-SPM Environments. Journal of Hydraulic Engineering 2018, 144, 04018055 .
AMA StyleJ. C. Winterwerp, Zeng Zhou, G. Battista, T. Van Kessel, H. R. A. Jagers, D. S. Van Maren, M. Van Der Wegen. Efficient Consolidation Model for Morphodynamic Simulations in Low-SPM Environments. Journal of Hydraulic Engineering. 2018; 144 (8):04018055.
Chicago/Turabian StyleJ. C. Winterwerp; Zeng Zhou; G. Battista; T. Van Kessel; H. R. A. Jagers; D. S. Van Maren; M. Van Der Wegen. 2018. "Efficient Consolidation Model for Morphodynamic Simulations in Low-SPM Environments." Journal of Hydraulic Engineering 144, no. 8: 04018055.