RE-DESIGNING AND OPERATIONAL ANALYSES OF THE SEDIMENT TRANSPORT CONTROL IN IRRIGATION CANAL NETWORK
Saman Shahid1, Shahid Ali1, Muhammad Abdullah Ahmad1, Sarfraz Munir2
ABSTRACT
The purpose of this research was to improve the existing design of the irrigation canals in Punjab. The design of an entire canal network is a tiresome and laborious work, where engineers spend months to design canals. Over the years, engineers and agriculturists in the Punjab have been trying to find a solution to the sediment transport problem which occurs in existing irrigation system. To address these problems, the canals can be analyzed to point out the flaws in design and operation mechanism. This study used a Physics based mathematical model, which can aid the engineers to design and analyze the canals on scientific basis. The research evaluated the existing design of BRBD link canal using SETRIC (Sediment Transport in Irrigation Canals) model based on Saint Venant shallow water equation and also, compared the sediment deposition’s result under various maintenance conditions for both Brownlie and Engelund Hansen predictor methods. The data related to BRBD canal, including its cross-sectional properties, hydraulics and sediment parameters were acquired from the Irrigation Department, Lahore. The paper also described the problem which exists in design and operation of the canal by comparing it with original field data. The BRBD canal achieved a regime condition in 1.5 years. The results of sediment deposition produced by Brownlie predictor were more accurate than Engelund Hansen. The sediment deposition volume for Reach 2 was about 593084 m3, whereas for Reach 1 Brownlie method predicted a sediment deposition of 26675 m3 and it was discovered that this large volume of sediments were deposited due to cross-sectional anomalies along the canal such as the geometry of Reach 2 varied abruptly; at one section the width was 21.54 m and the very next section it faced a contraction and reduced to 16.46 m and at RD 372+638, the width of channel expanded to 45.72 m, which then reduced to 43.28 m. Thus, to make possible efficient flow of water in BRBD Link canal and to decrease the sediment volume, the canal’s cross-sections were redefined. After this, the canal was remodeled on SETRIC by providing gradual changes in geometry rather than abrupt changes, which showed positive results, and sediment deposition was reduced by 35.25 %. If further modifications are made in the geometry of BRBD canal, the sediment deposition can be minimized which can help in saving billions of tax payer money spent on “Bhal Safai” and maintenance.
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