6 th International Conference on Advances in Civil Engineering (ICACE-2022) 21-23 December 2022 CUET, Chattogram, Bangladesh www.cuet.ac.bd/icace Page 1 of 8 ASSESSMENT OF WATER LOGGING PROBLEM IN CHAWKBAZAR AREA OF CHATTOGRAM CITY Prachi Rini Saha 1 , Md. Hazrat Ali 2 , Md. Mesbahul Islam 3 1,3 Graduate, Department of Civil Engineering, Chittagong University of Engineering & Technology, Chattogram-4349, Bangladesh, email: u1601121@student.cuet.ac.bd 2 Professor, Department of Civil Engineering, Chittagong University of Engineering & Technology, Chattogram-4349, Bangladesh, email: pdrmhali@cuet.ac.bd Abstract Chattogram is the commercial capital as well as major seaport of Bangladesh. Although, Chattogram is the backbone of country's economy, it suffers some of the most dangerous disasters like water logging. Water logging owing to intense rainfall makes the life of Chattogram city dwellers miserable almost every year as the roads and low-lying areas become inundated. Limited research information is currently available in the literature on water logging in Chattogram city. This research is concerned with the water logging problems in Chawkbazar area (16 no. ward) of Chattogram and its remedial measures. Land use, rainfall and population data were collected to measure the total surface runoff. Highest daily rainfall data of 10 years (2012-2021) are deemed, out of which the maximum rainfall of 222.077 mm occurred in June 2021 is utilized to compute the runoff. The Curve Number (CN) technique is used to measure the total surface runoff. The maximum surface runoff/discharge in the study area is found to be 21.73 m 3 /s in 2022, and the estimation of wastewater generation is measured to be 2.51 m 3 /s in 2022. The existing drainage capacity of the Chaktai khal is 17.15 m3/s, which is less than the estimated total discharge in the study area in several years, leading to water logging problems in rainy seasons. As a remedial measure, the Chaktai khal as well as its associated branch and distributaries, i.e., khal networks were designed to ensure effective disposal of surface runoff. Construction of a sluice gate at the Chaktai khal outlet is suggested to prevent backwater flow entrance into this khal during high tide. Keywords Rainfall; Surface runoff; Wastewater, Water logging; Existing khal capacity; Design khal network; Sluice gate. 1. Introduction Bangladesh suffers from several environmental challenges as a consequence of unchecked fast urbanization. The trend of urbanization is interlinked with financial development, which is generating ever-greater contributions to the national economy. However, when people’s growth is unusually rapid, most cities are incapable of adapting to the new challenges. Infrastructure, drainage, sanitation, and waste disposal are key concerns of human communities. On the other hand, discontinuities in the coverage and delivery of urban infrastructure harm the environment and alleviate urban efficiency, with negative implications for the natural economy. Chattogram, the commercial capital of Bangladesh, has a tropical monsoon climate that undergoes seasonal rains throughout the year that cause flooding in many portions of the city. Chawkbazar is one of the worst affected areas, which includes Khalpar, Fultola, Lalchand Road, Wali beg kha Mosjid, Katalgonj, Probortak, Gani Colony etc. In heavy rain, the city will be crippled due to excessive urbanization and the poor condition of the urban drainage system. Waterlogging proves to be very destructive for the transport system. Only a well-defined and well-developed road network can save time and provide flexibility and encourage local and foreign investors to invest in the country. But when roads are damaged or badly affected, numerous problems arise that can bring transportation facilities down. Waterlogging is one of the problems responsible for damaged roads and the unforeseen collapse of the transportation system. Since, Chattogram is the country's main seaport, damaged roads due to waterlogging severely affect the export-import business, ultimately hampering the national economy. Water stagnation also affects the city's food supply. The environment becomes unhealthy, and odours remain pervasive for numerous days. When waterlogged, standard life comes to a standstill. To solve this problem, the right concentration and means should be provided. Limited research information is currently available in the literature on water logging in Chattogram city. Ashraf and Chowdhury [1] examined the existing situation of Chaktai Commercial Area, assessing the causes behind the problems, inquiring about the likings and disliking of the stakeholders, and identifying possible solutions. Mohit et al. [2] developed a numerical model for the Chittagong city to predict water logging. Mahmood and Matin [3] estimated the capacity of the existing drainage channel network of Chaktai and Rajakhali khal and their branches. The primary aims of this research are to calculate the quantity of runoff that generates waterlogging, and to ascertain the existing criteria of the drainage system, and to design an effective drainage network in the study area to mitigate water logging.