Analysis of canal discharge management through remodeled structure at Guddu Barrage

Abstract

As vital hydraulic infrastructure, barrages and canals are crucial for agricultural irrigation in Sindh Province, Pakistan. Any deviation from the intended design discharge can significantly impact water resource management, leading to economic losses. The Ghotki Canal in Sindh faced challenges in receiving its allocated inflow, prompting an extension of the divide wall at Guddu Barrage to 589.59 ft. However, this extension inadvertently exacerbated the problem by reducing the Ghotki canal's inflow, resulting in a 166.7 ft gap between the original and extended divide wall segments. This study takes a unique approach, using a non-distorted physical model at a scale ratio of 1:85, to assess the influence of the divide wall gap across five scenarios, varying gap width and river flow rates from 100,000 to 500,000 cusecs. The findings highlighted the disruptive effects of the gap on flow regimes, notably affecting critical infrastructure such as the silt excluder and left pocket capacity. Alterations in the divide wall gap width predominantly impact the Ghotki Canal discharge while minimally affecting the Rainee Canal. Without a divide wall gap, the Ghotki Canal's head regulator draws 88% of the designated capacity, while the Rainee Canal consistently receives its total inflow share of 10,000 Cusecs. In conclusion, this study underscores the importance of structure remodeling in barrages for effective water resource management, emphasizing the need for nuanced approaches to optimize canal performance and sustain agricultural livelihoods and regional development.