urban drainage project (kcc) 3209
DESCRIPTION
Urban Drainage Project (KCC)TRANSCRIPT
Urban Drainage Project (KCC)
INTRODUCTION
Removal of surface or subsurface water from a given area by natural or artificial means is
called drainage. The term is commonly applied to the removal of excess water by canals,
drains, ditches, culverts and other structures designed to collect and transport water either
by gravity or by pumping. The Drainage System may define as a branched network of
stream channels and adjacent land slopes, bounded by a drainage network and converging
to single channel at the outlet.
Excessive rainfalls often cause severe water logging in roads and streets that disturb the
daily life of urban people. This is a common phenomenon now a day in Bangladesh
known as Urban Flooding, as the cities have not grown and developed in a planned way.
Khulna City Corporation (KCC) provide drainage and sanitation facilities within the city
corporation boundaries. Section 85 of the Khulna City Corporation Ordinance, 1991
includes regulations on the drainage facilities. Section 85 (1) outline “ subject to any law
for the time being in force , the Corporation shall provide an adequate system of public
drains in city area and all such drains shall be constructed, maintained, kept, cleared and
emptied with due regard to the health and convenience of the public”.
OBJECTIVES OF THE STUDY
The objectives of the present study are as follows:
To identify the problems of existing drainage system of Khulna City Corporation
area.
To identify the community people’s perception about the problems
To identify possible solutions for the existing drainage system of Khulna City
Corporation area.
To suggest some measures for the improvement of the existing drainage system of
Khulna City Corporation area.
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Urban Drainage Project (KCC)
STATEMENT OF THE PROBLEM
Large concentration of people in relatively small areas is recognized as an inevitable
historical process of urbanization. This process is continuing and predictions indicate that
by the end of this century, 51% of the world population will live in urban areas . In our
country, during various phases of urbanization of an area, various infrastructures are built;
these are mostly improvement of roads, provisions of power line, street light, supply water
etc and lastly the drain. However, urban drainage system should have priorities as it needs
extra space which is very difficult, after an area is being developed. Absence of proper
drainage system cause stagnant pool of water in urban areas. The stagnant water not only
creates discomfort to the inhabitants but it may also cause damage to adjacent structures
(Quabili, 1998).
COMMUNITY RESPONSE TO DRAINAGE PROBLEM
People’s response about existing drainage system and problems are listed below:
They are not satisfied with the existing drainage system,
They complain about irregular cleaning of pipes and manholes,
People of unplanned area complain about constructing high level roads than that of
houses,
They demand larger sewer system due to growth of multi storied buildings,
They claims about corruption of some employees of KCC for illegal sewer
connection,
They suggest government to take necessary steps to reduce sufferings of people.
During dry season there is no water logging or overflow problem. But during rainy season
unplanned area suffers much. Overflow from manholes creates nuisance. In unplanned
area, wastes from road side kitchen markets are often dumped into drains and manholes.
Planned area is free from this problem. Since in unplanned area storm sewer also serves
domestic waste water there is high potential to degradation of water quality in retention
reservoirs.
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Urban Drainage Project (KCC)
CONSTRAINTS OF DRAINAGE SYSTEM MANAGEMENT
Management of drainage system of an area depends on many factors such as social,
economical, geographical, administrative, environmental and political. Major constraints
of management recognized in this study are:
- inefficient administration and manpower;
- insufficient development fund;
- political biasness and instability;
- corruption in responsible authority;
- no coordination among concerned public service authorities;
- lack of long term land use planning;
- frequent change in plans, etc.
EXISTING DRAINAGE SYSTEM
Survey of a large number of households in Khulna city shows that about 68 percent of the
households have no planned drainage facilities in and round their premises while only 32
percent have some sort of drainage facilities.
The existing drains in KCC area are discharging into the nearby khals, rivers, low-lying
areas and beels. The existing drainage network within KCC area is shown in the following
table.
Table: Existing Drains in KCC
Area Length (Km) Type of Drain
Pucca (Km) Semi Pucca (Km) Kutcha (Km)
KCC 528.12 64.08 51.79 380.75
There is no underground storm water drainage system in Khulna City. Concrete box
culverts are being used for road crossing only. The existing drainage facilities in the fringe
and sub-urban areas are inadequate and unsatisfactory. The major KCC areas in the town
is not subject to direct flooding from the Bhairab-Rupsha river, but the low-lying areas
situated on the western and southern part of KCC are flooded by the rain water and tidal
effect during monsoon season .
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Urban Drainage Project (KCC)
There are 6 regulators and 8 sluice gates which drain out storm water from KCC area. The
10-vent sluice gate located at Alutala performs major drainage function of the Khulna
City. Out of these, 4 regulators drain out storm water into the Rupsha River and the other
two regulators drain into the Khudir Khal, the upstream of Gollamari River.
DRAINAGE CONDITION OF KCC
Wastewater is flow within drain. But the drainage condition is not well served. Only 45%
of the drains are well served, 52% poor served and 3% vulnerable conditions. But about
3112776 gallon per day (URDP, 1999) wastewater flows by the drain.
CONDITION OF DRAINAGE FACILITIES IN KHULNA CITY
45%
52%
3%
Well served
Poor served
Vulnerable
Figure: Drainage facilities condition of Khulna City.
EXISTING DRAINAGE PATTERN
The topographical features, existing internal network of khals and the river system in and
around the Structure Plan area shows the following five drainage zones:
a. Long and Narrow Strip of Flat Highland along both Sides of the Bhairab
and Rupsha River (Right Bank).
There is a long and narrow strip of flat highland along the Bhairab and Rupsha
River and stretching along northwest to southeast direction; this strip consists
of KCC core and urbanizing area.
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Urban Drainage Project (KCC)
The ground elevation of this narrow strip decreases sharply towards west and
south direction and gradually turns into a flood plain and swampy lands/beels
comprising flat and low-lying areas, criss-crossed by numerous tidal rivers
and channels.
The drainage water is discharged into the Bhairab and Rupsha River through
BWDB sluices/ regulators lying on the embankment cum road. The drainage
and flood protection works of this area are the responsibility of the LGED and
BWDB and covered by the STIFPP and BWDB Flood and Bank Protection
Projects.
b. Strip on the Eastern Side of the Bhairab and Rupsha River (left bank)
These areas are drained through natural drains, borrow-pits and ground
profiles sloping towards adjacent low-lying areas/flood plain and ultimately
into the outfall river/khals, viz., Bhairab, Rupsha, Atharbanki, Atai,
Majudkhali, etc. These areas comprise the fringe area of the town.
c. South and South-eastern Area on the Left Bank of Rupsha, Kazibacha
River
These are fringe areas and drained through numerous tidal creeks, low-lying
areas/beels and flat land situated in the flood plain of the major rivers, which
ultimately drained into the adjacent Rupsha, Kazibacha and Atharbanki rivers.
d. Western Part of the KCC Area along Left Bank of Gallamari River and
Khudir Khal.
The western part of KCC between Daulatpur and Kazibacha river is drained
by the upstream of Gallamari river or Khudir khal and downstream of
Gallamari river and ultimately through a regulator at Alutala which discharges
into the Kazibacha - Rupsha river. A small part of the catchment area
adjoining Khulna University area on the right side of the Gallamari river used
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Urban Drainage Project (KCC)
to drain by two BWDB sluices, but now drains towards west and into the
lower Sholmari river due to occurrence of siltation problem in the Gallamari
river and Khudir khal.
e. Northwestern Part of KCC and Structure Plan Area, Western Part of the
Structure Plan Area.
This catchment may be subdivided into two areas:
i. North and northwestern part of structure plan area between Daulatpur,
Phultala.
ii. Middle and southwestern part of the structure area between upper and lower
Sholmari river on the west (left bank of Sholmari river) and Gallamari
river/Khudir khal on the east (right bank of Gollamari and Khudir).
WATER -LOGGING AREAS DUE TO POOR DRAINAGE
Inundation and inadequate drainage in structural plan area are occurring due to localized
storm rainfall (internal flood) affecting drainage system. External flood is not likely to
occur since the structure plan area is situated in the tidal zone. The areas suffering from
drainage congestion has been identified during moderate to heavy rainfall. The inundated
areas associated with drainage congestion are mentioned below:
- Natun Bazar
- Rupsha
- Tutpara
- Shipyard areas
- East Bania Khamar
- Boyra
- Rayer Mohal
- Khan-A-Sabur road (infront of KDA building)
- Nodal Point of Khan Jahan Ali and KDA Avenue (nearby and surrounding
Royal Hotel)
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Urban Drainage Project (KCC)
The reasons for water-logging have been identified as follows:
(i) Improper operation and maintenance of khals/drains,
(ii) Blockage in the existing khals/drains,
(iii) Absence of integrated network comprising secondary and roadside
drains,
(iv) Haphazard expansion of the regional settlements which obstructs the
natural drainage system,
(v) Uncontrolled and haphazard disposal of solid waste into the drainage
system,
(vi) Siltation in the drainage channels with consequent reduction of
discharge capacity.
FUTURE ASSESSMENT
There is no planned drainage system in the fringe areas of KCC as well as outside the
KCC area. The drainage scheme may be extended and taken up phase wise with the
progress of urbanization which depends on some factors, such as population growth, rate
of urbanization, extent of flood damage in the area, affordability of KCC and viability of
the project etc.
The need for improved drainage system will be greatly influenced by the physical
development of the Structure Plan area and a Drainage Master Plan will be needed for the
Structural Plan areas. The land use activities are guided by KDA; on the other hand KCC,
DPHE and LGED have their own drain improvement programs within and out side KCC
area. Therefore, a high degree of coordination is necessary between these organizations for
improvement of drainage network within the Structure Plan area.
The various projects of BWDB, LGED and KCC concerning flood protection works, river
bank protection works and drainage improvement works and a proposed Drainage Master
Plan will help solve many drainage problems.
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Urban Drainage Project (KCC)
OUTLINES OF PROPOSED DRAINAGE IMPROVEMENT PLAN
Open drainage system is followed in Khulna as it is cheaper than piped drain and easy to
maintain. Piped storm water drainage system could not develop because it is expensive to
construct, operate and maintain such system and also beyond the present affordable limit
of KCC. The situation however, demands a comprehensive Drainage Master Plan with an
integrated network of drainage system for the Structure Plan area and a link-up with the
Secondary Town Integrated Flood Protection Project recently executed by the BWDB and
LGED and the existing drainage sluices and regulators constructed earlier by the BWDB.
The existing drainage system will provide a basis for a comprehensive drainage scheme in
which the khal network, pucca/kutcha drains and borrow-pits may be up-graded to act as
the main framework for improved and integrated as well as viable drainage system for the
Khulna City Structure Plan area which will serve the drainage need during the peak
monsoon period when the drainage stands critical.
Policy Drain/1 : Formulation of storm water drainage improvement plan
In order to develop a practical and affordable solution to the storm water drainage
problem, formulation of a drainage improvement plan for the areas which are not covered
by BWDB and STIFPP projects for storm water drainage may be proposed. For this
purpose the following tasks will be needed:
(i) topographical surveys of the area including levels of existing drains and
culverts
(ii) assessment of extent and frequency of flood damage to the flood affected areas,
(iii) design of primary and secondary drains, and retention areas required,
(iv) review of technical, environmental, institutional, economic and social
feasibility of the proposed works,
(v) planning of implementable phases
(vi) detailed design,
(vii) provision of adequate drainage reserves and right-of-way,
(viii) maintenance program including assessment of manpower requirements,
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Urban Drainage Project (KCC)
(ix) funding mechanisms for construction phases and operation and maintenance of
the system,
(x) application of practical standards for storm water drainage,
(xi) selection of realistic return periods of rainfall and river water levels based on
the experiences from the STIFP and BWDB projects,
(xii) system design following existing drains and culverts as much as possible and
natural topography of the area, keeping land acquisition to an absolute
minimum.
It is very important to point out that the KCC should develop its ability to clean and
maintain the designed drainage systems. Therefore, institutional and technical
strengthening of the KCC and planned maintenance procedures will be an important factor
for any drainage improvement project.
Policy Drain/2 : Phase-wise implementation of drainage improve-ment plan
Priority areas should be first identified during preparation of comprehensive topographical
surveys and drainage outline plan, through observed physical conditions, discussions with
the local residents, and detailed discussions with different authorities. Specific attention is
to be given to the improvement of the drainage systems in the town centre and in the
densely populated residential, commercial and industrial areas in the structural plan area.
The priority for the proposed works should be grouped into different priority levels for
phase-wise development.
The KCC Authority will confirm the local priorities and select the remaining improvement
works as Second Priority Works on the basis of availability of funds.
Pumping stations comprising high capacity pump should be installed for dual purpose, i.e.
drainage and irrigation in dry season.
More sluices with flap gates at outfall points on primary khals/river and in the existing
protective embankments to control backflow during high stages of rivers/khals
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Urban Drainage Project (KCC)
Re-excavation, regarding, deepening, widening of drainage khals comprising the network
of khals should be done on priority basis.
Non-structural measures prescribed for site development and plinth levels of different
structures to be followed as prescribed.
The existing agricultural lands /lowlands lying in the fringe and semi-core areas of the
structural plan area is not only serving as good retention basins but also playing an
important role in decreasing magnitude of flood in the core/semi-core areas.
Further, it may be noted here that though urbanization is progress, but all the lands
including agricultural lands within the structural area will not be urbanized by the year
2020 and that some low and agricultural lands will exist beyond this period, which will
serve as storage basin/ detention pond and reduce magnitude of flood significantly in the
structural plan area during monsoon season.
Policy Drain/3: Improvement of environmental situation through improved drainage
system
Improvement in the drainage system will improve the environmental situation in the water
logged areas by eliminating stagnant water and associated problems like odors from
decaying solid wastes, insects, scams and disease vectors as well as the incidence of local
flooding due to rainfall.
Although the drains are intended to remove storm water, but they also receive sludge flow,
septic tank effluent and other locally contaminated water. For the above problem the
following mitigating measures may be taken :
(i) KCC will educate and take action against polluters;
(ii) Provide better sanitation for low-income and town center areas through construction of
pit latrines and public toilets respectively;
(iii) protect the outlet of drains by providing Oil and Silt Traps as necessary and Trash
Racks and Sumps in the drainage system to reduce cost of routine cleaning and
maintenance work;
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Urban Drainage Project (KCC)
Policy Drain/4: Complementary non-structural measures to protect right of way and
other aspects
In addition to physical works program KCC should adopt complementary procedures and
policies in maintaining a proper drainage system within its jurisdiction. In the long run
these “non-structural measures” will improve the drainage situation and resolve the
drainage problems. The following non - structural measures are recommended:
a) Provide adequate funds in all annual budgets for carrying out routine
maintenance programs;
b) Identify, on the basis of the Drainage Improvement Plan, all areas where
existing main drains are located or will be required in future and enforce existing
legislation to prevent unauthorized development or encroachment on the drain alignments;
c) Identify, on the basis of the Drainage Improvement Plan, all low-lying areas
which are prone to regular flooding due to drainage congestion and cannot be
economically drained by gravity systems; inform residents and enforce building control
regulations to prevent development at levels which would be dangerous for future
residents;
e) Undertake a long range program to reduce the “source” of intrusion of sludge,
silt, garbage and effluent into the drainage system, thereby reducing the cost of the long
term maintenance operations, by : (i) prohibiting dumping of garbage into the drains by
enforcing regulations; (ii) providing convenient local collection points and more efficient
removal services; (iii) prohibiting dumping of night soil/wastes into the drains by
enforcing regulations and more efficient removal services; (iv) prohibiting direct septic
tank connections to the drainage system by enforcing regulations to prevent this; (v)
installing trash racks and sumps at convenient locations to facilitate collection of silts and
floating garbages;
(f) Introduce public information campaign to make people more aware of the
problems, hazards and unacceptable practices,
(g) Ensure proposed channel geometry to keep water way free from all unwanted
intrusion, encroachment etc.;
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Urban Drainage Project (KCC)
Policy Drain/5: Operation and maintenance of drainage system
Operation and maintenance will comprise the following classified activities:
(i) Preparation
(ii) Maintenance
(iii) Rehabilitation and
(iv) Replacement.
Operation is related to drains involved in carrying out activities in the field of
conservancy, collection and disposal of solid wastes from drains. Maintenance relates to
maintenance of equipment and drains. Rehabilitation and replacement relate to provision
of rehabilitation work and replacement of equipment. KCC should develop a routine
preventative maintenance program for the drainage systems so that the structural
improvements will provide a lasting benefit. It is, therefore, recommended that the KCC
develop a comprehensive conservancy program for maintenance of drainage system which
is maintenance activities and scheduling of these activities, methods and equipment,
staffing needs and any appropriate re-organization which may be necessary.
The following guidelines may be followed for development of staffing and equipment for
a preventative maintenance program:
a) Drains should be cleaned regularly;
b) One cleaner/sweeper should be provided for every 50 m of primary/secondary
drains, 150 m of tertiary/local drains per day (i.e. 1.5 km primary/secondary drains or 4.50
km of tertiary drains per month supervisors should be provided at the rate of 1 jamadar for
each 10 sweepers, and 1 sanitary inspector for each 4 jamadars;
c) adequate equipment should be provided for efficient operation of the cleaning
crews, including wheel barrows and miscellaneous hand tools for each drain cleaner, 3 ton
dump truck (s) for waste transport and disposal (garbage truck will serve on demand), and
pump (s);
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Urban Drainage Project (KCC)
RECOMMENDATIONS
In some specific KCC and outside KCC areas, there are some low-lying areas, which are
subjected to waterlogging during and after heavy rainfall in a year between August and
October. The depth of stagnant water varies from 0.25 to 0.35 m and usually lasts for 3.0
to 5.0 hours from place to place. The waterlogging situation is likely to further aggravate
in the years to come with growing urbanization. The prime causes of this water-logging
are as follows:
(i) Lack of cleaning and maintenance of the khals/drains,
(ii) Unplanned and inadequate drains in the existing drainage system,
(iii) Obstruction and encroachments in the khals/drains and drainage paths,
(iv) Lack of construction and integration of tertiary, secondary and primary drains,
(v) Non existence of drains in different places.
The following recommendations may be made for future Drainage Improvement Plan:
Proposed drainage system should be designed to discharge most of the storm
run-off by gravity flow; pumping is necessary when gravity flow will not work
and when the water level at outfall is higher than the drain water level.
Existing khals constitute the storm water run-off delivery system.
Timely undertaking of drainage issues and improvement plan in the structural
plan area are to be considered as timely venture to formulate an investment
project to reduce sufferings of the residents.
Any proposed drainage improvement plan should be justified technically,
economically and socially. Priority program should be recommended for
implementation. The program after implementation will mitigate major
drainage problems in the core and semi-core area where the density of
population varies from high to medium.
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Urban Drainage Project (KCC)
For improvement of drainage condition, improvement in respect of solid waste
management and household sanitation is considered to be vital. As such, these
components should be included in any proposed drainage improvement project.
KCC should take immediate steps to remove the unauthorized structures like
earthen barriers; small culverts etc. from the drainage paths/khals and ensure
clear right-of-way.
KCC should execute any drainage improvement project as implementing
agency. If KCC is lacking in planning and detailed design works for
implementing this project, it will need the assistance and supports of local
consultants for detailed design and implementation support. This will develop
the skill of manpower of KCC through transfer of technology and training.
Any proposed drainage improvement plan should be exchanged with other
utility organization to avoid any overlapping and duplication. As such, a high
degree of close co-ordination with DPHE, BWDB, LGED, PDB and other
utility organizations should be maintained during the project implementation
stage so that disruptions to services of these utility organizations do not take
place.
Cost of the drainage improvement project should be funded as grant to KCC or
by Aid giving agency because the KCC is not in a position to implement this
project from its own resource.
KCC should involve community/NGO in cleaning and maintenance of the
drainage and environmental sanitation activities.
KCC should improve significantly in revenue collection and efficiency in
financial management so that KCC can properly maintain the drainage system.
If possible the knowledgeable NGO could be employed for accurate
assessment of individual KCC residents.
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Urban Drainage Project (KCC)
Pipe drain may be suggested where road is narrow and where there is no space
for roadside drain.
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