4.4.4
Storm Water Drainage:
In order to alleviate the situation, urgent corrective measures are necessary for
rehabilitation of the storm water drainage system.
i.
Development of Digital Drainage Network : The CDGK needs to
immediately develop a comprehensive database on GIS platform to
identify and develop existing drainage network layers with associated
databases informing the available flow capacities. Data needs to be
provided by KWSB offices and survey and verification to be carried out in
coordination with the KWSB and TMA offices.
ii.
Registration of Trouble Spots: Immediate attention is required at all major
problem areas such as Teen Talwar, Nursery - Post Office main Shahrae-Faisal and FTC intersection, Johar Mor Bridge leading to Johar
Chowrangi both sides in Gulsitan Johar, I.I. Chundrigar Road and all
major intersections, underpasses and bridges. The requirement is to
immediately conduct topographic survey of such low-lying areas/locations
and evaluate and analyze the existing drainage in terms of its efficiency
and carrying capacities for last 50-100 years storm recurrence interval.
The volumetric runoff should be calculated based on the selected storm
events and a computer model should be generated identifying the flow
patterns in these identified localized positions.
iii.
Identification of Catchments Areas: The catchments areas need to be
redefined and existing drainage should be examined in the light of local
topography of the area.
iv.
Identification of Local Services Area- Catchments and watersheds: In
secondary phase of study delineation of catchments and watersheds in
the 18 towns will be required to assess the drainage pattern in localized
environment. This will require coordination and input at each Union
Council and TMA level. The layout of the existing and proposed drainage
system is to be superimposed on the topographic map of the area and the
points of inlet of runoff to the system identified.
v.
Hydraulic Survey of All Major Channels: All major disposal channels and
nalas are to be examined for hydraulic carrying capacities and necessary
suggestive measures and geometrical redesigning option to be proposed
and evaluated for a comprehensive solution to the drainage problems.
vi.
Future Development: In estimating the future rainfall runoff rate, it may
also be necessary to estimate the future development within the tributary
areas. The present development patterns will serve as a guide and
predicting future development but such factors such as zoning regulation
and other city or area planning documents must be evaluated.
A mega project for construction of new storm water drains including
replacement of old systems and resettlement of the evictees from
affected land around nallahs shall be developed under special financial
package to be provided by the Federal and Provincial Governments.
vii.
Installation of Gauging Station Network: It is proposed to install gauging
stations on town basis to monitor precipitation and flooding in local areas.
The city of Bangkok, Thailand has developed a fully functional application
which provides GPRS based information on mobile phones the runoff and
flooding situation in the event of storm and provides safe passages and
directions to vehicular traffic users. It is highly recommended that CDGK
evaluate the existing flood protection and disaster mitigation measures
and procedures of the city of Bangkok which in addition to monsoons also
faces tropical storms from South China Sea
viii.
Acquisition of Existing Topographic Data: It is suggested that the CDGK,
Works & Services Group of Offices should acquire the digital topographic
data from the consultants and contractors of all the ongoing and previous
infrastructure developments works. This exercise would provide
immediate availability of the localized topographic contours and would
assist the technical experts to identify the existing drainage problems and
suggest measures.
ix.
Infrastructure Monitoring Cell: A Cell consisting of experts should be
established for the evaluation of ongoing development works and assess
projects from the overall perspective of road/ transportation, water supply
/ sewerage and drainage schemes. Individual departments and
compartment studies preclude the possibility of analyzing on the basis of
integrated and holistic approach.