Since there was a lack of necessary data, the research team collected field level **data** in the summer of 2017 from both cities to develop the drainage model. Data pertaining to the primary water level, water discharge, and existing drainage networks and their cross-sections were collected from the field. The primary **data** were used for both model development and calibration. Moreover, historical water level **data** (from 1938 to 2015) for the Surma River and rainfall **data** at Sylhet recorded by the Bangladesh Water Development Board (BWDB) (from 1957 to 2011) and the Bangladesh Meteorological Department (BMD) (from 1957 to 2015) were collected (Table 3).