Utilization of Reverse Slope to Increase Full Supply Level in Small Irrigation Channels | [Technical Journal • 2021]

Author(s):

1. M. Masood: Centre of Excellence in Water Resource Engineering, University of Engineering and Technology, Lahore, Pakistan.

2. M. S. Amin: Agricultural Engineering Field Wing, Government of Punjab Lahore, Pakistan.

3. G. Nabi: Centre of Excellence in Water Resource Engineering, University of Engineering and Technology, Lahore, Pakistan.

4. A. H. Azhar: Directorate of Hydrology, Mangla Dam Organization-WAPDA, Mangla Dam, Pakistan

5. M. Babur: Civil Engineering Department, University of Central Punjab, Lahore Pakistan

Abstract:

In this study optimal limit of the reverse slope, downstream of an irrigation outlet, where flow is supercritical was studied to create sufficient working head required to irrigate elevated fields in the command area of a watercourse. Three different types of outlets Adjustable Orifice Semi Modular (AOSM), Pipe and Open flume were designed and constructed in the lab. Various values of reverse slopes were incorporated in one-meter and two-meter length of the watercourse bed, downstream of the selected outlets, at a constant value Full Supply Level (FSL) of the canal. It was observed that FSL of watercourse increased with increase in reverse slope. Reverse slopes values of -0.10 and -0.15 incorporated in a length of one meter were found most suitable for an outlet of one-cusec discharge capacity. It was observed that FSL of watercourse increased with increase in reverse slope value up to -0.15 and then started decreasing gradually at -0.20. The outlet discharge decreased slightly (3%) for reverse slopes 0.10 to -0.15 and significantly (26%) at reverse slope -0.20, by submerging the outlets. Reverse slope incorporated in one-meter length of the channel bed was more useful than incorporated in the two-meter length of the channel bed. The results obtained for AOSM and pipe outlets were identical. Open Flume outlets found not to be fit for induction of reverse slope. The best hydraulic section for the reverse slope was with upstream width equal to the throat width (Bt) of the outlet, expanded in the direction of flow to join the designed width of the channel.

Page(s): 9-17

DOI: DOI not available

Published: Journal: Technical Journal, Volume: 26, Issue: 3, Year: 2021

Keywords:

Watercourse , Reverse Slope , Outlet , Full Supply level

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