Hydrologic Performance of Drainage Network Under Different Climatic and Land-Use Conditions, A case study of Chattogram

Abstract

The recent alternation of urban hydrology is seen significant due to the growth of urban sprawl. In the changed urban hydrology and urban settings, the city drainage is seen underperformed and problems are manifolds. This study therefore aims to evaluate the hydrologic performance of drainage under different land use patterns demonstrating urbanization effects using the Mahesh Khal in Chattogram as a studied watershed. This study analyses land use pattern of the study area with the data collected through field investigation and also gathered from the secondary sources using ArcGIS 10.4. The change patterns are realized portraying scenarios with statistical significance. The study revealed that the trends of built-up area is significantly high figuring out over doubled in last 30 years period; 24% in 1998 to 53% in 2018 compromising the lost of open water and vegetative surfaces. In align with such changes, the peak discharges found for 2, 5, 10, 25, 50 and 100 years return period were 20, 29, 36, 44, 50 and 57 𝑚3𝑠−1, respectively, and were seen varied mostly with the curve number and imperviousness. The discharge in combination with tidal inflow into the Khal exceed the capacity of the existing capacity and is seen underperformed. The dumping of solid wastes, improper management of Khal, changes in surface slopes of connecting drains are found key factors. The study suggests that maintaining vegetation and surface slopes may increase the performances of drainage.