DefinePK

Abstract

The study evaluates the performance of J-head spur dikes in controlling lateral migration and bank erosion along the right bank of the Indus River, downstream of the Ghazi Ghat Bridge in Dera Ghazi Khan district, Punjab, Pakistan. The erosion of the outer bank poses significant threats to infrastructures and local settlements, highlighting the need for spur dikes to regulate flow and implement protection measures. The HEC-RAS 2D model was used for this analysis. The results revealed that spur dikes oriented upstream were generally ineffective due to clogging of an active creek, whereas a downstream orientation at 120° was found more effective in diverting flow towards the main channel than at 135°. To manage high flood events, it was proposed to raise left bund by 2 ft and the spur at RD 138+000 by 1.50 ft. The performance of existing spur dikes was analyzed based on the prevailing spacing of 2 to 5 times the length of the spur at RD 138+000. Additional spur dikes at RD 141+500 and RD 154+000, near Samina Town and Basti Bhai, were introduced to improve flow patterns and protect irrigation infrastructures and local settlements. It was observed that at low flows, the velocity along both creeks was slightly declined from 1.09 to 0.92 ft/sec, while at high flows, the velocity reduced from 1.92 to 1.33 ft/sec between RD 138+000 and RD 148+000, and from 2.69 to 2.34 ft/sec between RD 148+000 and RD 165+000. These findings emphasize the need for customized spur dikes designs, considering orientation, spacing and hydraulic conditions. The findings of this study provide valuable insights and may be used to enhance flood management, infrastructure safety, and sustainable riverbank protection for future interventions.