Analysis and Modification of the Drainage System in Dhamrai Municipality, Bangladesh: A Sustainable Approach with LID Implementation

Urbanization, climate change, and aging infrastructure are putting pressure on urban drainage systems in countries like Bangladesh. This research investigates long-term drainage solutions for Dhamrai Paurashava, a medium-sized municipality located northwest of Dhaka. Using a multi-method approach that combines hydrological modeling, field verification, and Low Impact Development (LID) measures, the study addresses waterlogging, flood risk, and drainage deficits. The Environmental Protection Agency's (EPA) Storm Water Management Model (SWMM) was utilized to simulate the existing drainage system beneath varying rain intensities. GIS supported flood hazard maps revealed the most significant areas of inundation. Major drainage infrastructure improvements, including widening drains, creating new channels, and streamlining outfalls, resulted in a maximum reduction of flood depth by as much as 20%. Along with these infrastructure enhancements, LID (Low-Impact Development) strategies, such as rainwater harvesting, bioswales, and constructed wetlands, were also proposed. These green interventions effectively reduced the amount of runoff, facilitating sustainable stormwater management. Field confirmation and climate-corrected rainfall data emphasized the requirement for adaptive, site-specific measures. The study promotes a hybrid strategy combining natural and engineered solutions, aiming to develop resilience to climate uncertainty and urban pressure. It is a prototype for other cities seeking low-cost, community driven drainage solutions. The application of cutting-edge hydrological modeling and stormwater quality analysis is worth consideration in further studies to reduce pollution risk. Through the combination of technical analysis and nature-based design, the study aims to enhance long-term urban resilience in exposed, rapidly growing cities.