Abstract:
Water is a crucial and fundamental element in irrigation and agriculture. Understanding water
dynamics in natural and engineered channels allows irrigation experts to distribute water
efficiently. The irrigation canal network of the Layyah Division is critical to supporting agriculture
activities of Punjab but faces significant constraints in the operation and management of canals.
The main problem in the canal operation is water shortage occurring in the lower Indus Branch
supplying water to the Munda Branch. The performance of a canal is determined by its water
conveyance efficiency, among other factors. L-Sections (Longitudinal sections) of the canals
provide significant details on hydraulic parameters such as canal bed width, flow velocity,
Manning's roughness coefficient, and F.S.L (Full Supply Level). However, in most systems, canals
are not operated on design discharges because either the canal capacity is insufficient or operated
under their designed flow rates. A hydraulic model for a canal is helpful in reproducing practical
considerations and operations. The current study represents the development and comparison of a
1D hydrodynamic model of the Munda Branch with a design discharge of 39.5 m3
/s and length of
34.13 km with its 9 distributaries using the Hydrologic Engineering Center River Analysis System
(HEC-RAS) and BASEMENT software. Three scenarios were modeled to evaluate the water
surface profiles at various cross sections of the Munda: 1. behavior of the canal without lateral and
inline structures, 2. the influence of the lateral distributaries, and 3. the impact of inline structures
along the canal. Field data and design discharges were used to calibrate and validate the model.
The results demonstrated consistent water levels between HEC-RAS and BASEMENT with minor
discrepancies. Most of the cross sections of the canal remained submerged under design discharge
conditions, underscoring the limiting conveyance efficiency of the Munda Branch. The study
highlights the applicability of both modeling tools in design and performance assessment in
irrigation systems.
