Unraveling Urbanization's Impact: A Case Study on Water Retention in Colombo Wetland Complex, Sri Lanka

Abstract

Nature-based solutions (NbS) enhance urban water management by mimicking natural hydrological cycles. This study examines the Colombo Wetland Complex (CWC) in Sri Lanka as an NbS for stormwater management, highlighting urbanization's impact on flood control. From 2001 to February 2024, Colombo's wetlands decreased by 2.68 km², reducing water absorption by 166,346.98 m³ and increasing stormwater flow by 1.875 m³/s. The flood control unit value of the CWC is $72 USD/m², comparable to hard-engineering solutions. The study underscores the importance of wetlands for flood control and calls for their preservation to enhance urban resilience and sustainable development.

Keywords: Nature-based solutions (NbS), urbanization, wetlands, flood, Colombo Wetland Complex