Study on Water Supply and Drainage Problem in Khulna City

Abstract

Khulna, the third largest divisional as well as the metropolitan city of the country, is located in the south-western region between 22°30' N latitude and 89° 20' E longitude. It is an industrial as well as the second seaport city. The population of the city has been increasing along with the development of the city since the early eighties. At present, the population in KCC area is about 0.80 million. According to forecast, the population in the city will be 103.64, 133.82 and 171.67 million in the year 2011, 2021 and 2031 respectively. Khulna City Corporation is the responsible authority lo supply water to the city dwellers. Ground water is the main source of KCC supply; apart from this a small quantity of water is supplied from the surface water source. At present, KCC is supplying water at the rate of about 27300m3/day of which 97.44% from ground water source and 2.56% from surface water source. KCC water supply network is working only in 23 Wards out of 31, no water supply network there in 8 Wards (Ward-I to Ward-8).

Apart from KCC wells, ground water is being carried out by public, private, industrial and institutional wells. Al present, about 120400 m3/day waters arc abstracted Irom the ground and surface water sources. Of this, only 700 m3/day (0.58%) comes from surface water source and the remaining 99.42% are from ground water source. About 26600 m3/day (22.1%) is abstracted by KCC wells, 43600 m3/day (36.2%) by industrial and institutional wells and 49500 m3/day (41.1%) by private and public wells. The drinking water requirement of city people are met taking only 4.2% from KCC supply, 89.9% from other wells and 5.9% from ponds and rivers. The major fractions of water requirements of city people for cooking, washing and bathing are met from ground water abstracted by other wells.

It reveals that huge quantities of waters arc abstracted from ground water source and day by day it is increasing. But groundwater resource may not be unlimited. KCC undertook few hydrological studies to quantify the ground water resource in KCC area. None of the study reports clearly specified the quantity of the groundwater resource in KCC area. The last hydro-geological study was undertaken by KCC in 2005 and the consultants finally estimated that the ground water reserves in KCC area may continue up to next 25 to 30 years at the present rate of abstraction (BRGM/LGED, 2005 ). Physical, chemical and bacteriological quality of KCC supply water was determined in three seasons. Physical and chemical quality parameters were within acceptable limit with a minor seasonal variation according to BOS and WHOGY but bacteriological tests revealed that the supply waters were microbiologically contaminated. Substantial numbers of contaminants- TTC and E.coli were observed in almost all samples. Quantitative health risk was assessed with QHRA model and it was found that due to the presence of TIC and Eicoli, the KCC supply water is associated with high risk of disease burden to the users. It was found that due to the presence of ITC, the KCC supply water is associated with viral burden varying from 2.033 μDPY to 3.4μDPY, exceeding the allowable limit 1.70 μDPY; bacterial burden varying from 0.73 μDPY to 3.33 μDPY, where the allowable limit is 0.40 μDPY and protozoa burden varies from -1.56 μDPY to 0.83 μDPY, where the allowable limit is -1.90 μDPY according to WHOGV.

Similarly, due to the presence or E.coli, the KCC supply water is associated with viral burden varying from 1.67 μOPY to 3.43 μDPY, exceeding the allowable limit 1.70 pDPY; bacterial burden varying from 0.33 μDPY to 2.20 μDPY, where the allowable limit is 0.40 μDPY, and protozoa burden varying from -1.93 μDPY to 0.47 μDPY, exceeding the allowable limit -1.90 μDPY according to WHOG . Then it can be said that KCC supply water is associated with high disease burden.

In KCC area, there are about 528.120 km drainage network of which 175.43 km (33.22%) arc primary drain, 150.45 km (28.49%) arc secondary and 202.24 km (38.29%) arc tertiary drain and among those 291.230 km (55.14%) are pucca, 51. 790 km (9.81 %) arc semi-pucca and 185.10 km (35.05%) are kutcha drain. The average drainage density in the city is 11. 79 km/km2, the lowest density is 3.06 km/km2 in ward 31 and the highest drainage density is 33.88 krn/ km2 in ward 23. All the drains have 49 major outlet points in the four main rivers as Bhairab, Rupsha, Mayur and Gallamari around KCC. It is revealed from the KDA, 2002 report that around 68% households of the Khulna city have no planned drainage facilities and only 32% have some sorts of facilities in and around their premises. The cleaning and maintenance performance of drains in KCC is very poor. Waste loadings in drains due lo some wastewater parameters were assessed. The waste loading of the parameters vary with the seasonal variation or flow rates. All the drains have the flow in rainy season but there is no flow in some drains in other seasons. It is revealed that waste loading for most of the parameters is the maximum in rainy season and minimum in spring because the flow rate is the maximum in rainy season than that of spring. A questionnaire survey was carried out among 385 residents within KCC area. The main objective of this questionnaire survey was to assess the perception of the city dwellers on the services provided by KCC in regard to water supply, drainages and its muiutcnnuccs and cleaning, related health and hygienic environmental conditions. The people are not satisfied with the water supply from KCC and very much dissatisfied with the service provided for the cleaning and maintenance of drains. KCC organizational structures were evaluated and it was identified that Water Works Department of KCC does not have sufficient technical staff and no planned activities exist to assess the quantity as well as quality of KCC water supply. Some recommendations were placed to improve the overall water supply system of KCC, including preparation of water safety plan and establishment of a technical surveillance unit for routine monitoring the quantity and quality of water. This thesis has identified the major problems in KCC water supply; there is no organized and planned water supply plan, mechanism lo monitor the production and yields of wells, routine checking and maintenance or wells and pipe line connections. plan to explore the new water supply network to the new settlements, no quality assurance activities, no skilled manpower for checking the water quality parameters etc. Dependency on ground water source is increasing and KCC has no report on quantity of groundwater reserves, how long abstraction can be continued and abstraction rate etc. The major problems related to drainages are mainly the lack of proper cleaning and maintenance, unplanned drainage construction and encroachment of drains paths for developments of other infrastructures.