Feedback from a Successful Pilot Project in a Highly Complex Hydraulic Context – The case of the Drainage System in the City of Cuttack, India

Like many Indian cities, Cuttack, with a population of about 600,000, relied on a single sewer canal collecting both wastewater and rainwater. During the monsoon season, this canal frequently overflowed, severely disrupting daily life. The project’s main objective was therefore to create a new wastewater collection network and convert the existing canal into an efficient drainage system. Located in the Mahanadi River delta, where monsoon flows can exceed 40,000 m³/s, the city is entirely surrounded by a dike, creating major drainage constraints. A very gentle slope, limited space for water storage, and gates controlling canal outlets further complicated the situation.

With support from JICA, a pilot project was implemented over nearly ten years, from design to construction, leading to the installation of a high-performance drainage system. From the design stage, dynamic hydraulic modeling was developed using PCSWMM software. The model integrated all relevant structures and their operational management, including drainage conveyance, storage basins, low-lying urban areas, pumping station operations, and dynamic valve control linked to river levels. Project rainfall events and historical extreme monsoon events were simulated to size the infrastructure and assess system performance under realistic conditions. This approach enabled the identification of optimal solutions, reducing flood volumes and durations by 80 to 90% compared with previous conditions.

Construction posed significant challenges and required frequent design adjustments. Much of the drainage network runs through narrow streets bordered by buildings, making it impossible to shut down the system during works. An innovative construction approach was therefore adopted, involving short, phased sections, temporary water diversion using mobile pumps, and extensive use of steel sheet piles to support deep excavations and protect nearby structures.

Now fully operational, the Cuttack drainage system has proven effective even under extreme conditions. The project highlights the importance of an iterative process combining hydraulic modeling and construction constraints, offering practical guidance for other cities facing similar urban drainage challenges.