FLOODS IN PAKISTAN
CAUSES OF FLOODS IN PAKISTAN
Flooding in rivers is generally caused by heavy concentrated rainfall in the catchments during the monsoon season, which is sometimes augmented by snowmelt flows. Monsoon currents originating in the Bay of Bengal and resultant depressions often cause heavy downpour in the Himalayan foothills. These are additionally affected by weather systems from the Arabian Sea (by seasonal lows) and from the Mediterranean Sea (through westerly waves) which occasionally produce destructive floods in one or more of the main rivers of the Indus system. However, exceptionally high floods have occasionally been caused by the formation of temporary natural dams by landslides or glacier movement and their subsequent collapse. These are large seasonal variations in almost all the river discharges, which further aggravates the river course and morphology.
The major rivers cause losses by inundating areas along their banks, by damaging irrigation and communication facilities across or adjacent to their banks, and by erosion of land along the riverbanks. In the upper part of the Indus Basin System, flood water spilling over the riverbanks generally returns to the river. However, in the lower Indus Basin, where the Indus primarily flows at a higher elevation than adjoining lands, spills do not return to the river. This phenomenon extends the period of inundation, resulting in even greater damages. Although embankments built along almost the entire length of the river in Sindh and at many locations in the upper Indus Basin have provided some protection against floods, poor maintenance of the bunds causes breaches. Such breaches often cause great damage because of their unexpected nature and intensification of land use following the provision of flood protection.
Pakistan, being the downstream user of the rivers and also embroiled in political conflicts with the upper riparian state India, has to be particularly careful about flood management. India has several structures in place that augment its capability to transfer flood surges to Pakistan - this has happened in the past. India constructed the Bhakra Nagal Dam on Sutlej, the Pong Dam on the Beas and the Thein Dam on the Ravi.
THE PRO-FLOOD PERSPECTIVE
It has been long known that river systems have a natural capacity for dealing with the threat of floods and the natural processes embodied in them provide many benefits. Flood plains, wetlands, and backwaters are commonly referred to as "nature's sponges"; they absorb excess water, purify it and can be tapped during lean periods. They act as spawning grounds for fish and wildfowl. The floods themselves replenish agriculture soils. Communities living around these areas adapt to this natural rhythm and use its bounty to ensure reliable and sustainable livelihoods. According to some experts, the 'flood pulse' is not a disturbance but flood prevention is. Some feel that large dams like Tarbela and Mangla have contributed to disturbances on a large scale. This also supports the view that dams do not prevent floods, they merely create 'flood threat transfer mechanisms'.
The solution is to work with communities, rely on their knowledge and to supplement their flood mitigation and coping strategies. "Rod Kohi" (flood irrigation) is widely practiced particularly in areas of hill torrents. Small dams, recharge dams and delay action dams have been constructed on a number of small streams for irrigation by small communities to meet their local irrigation needs. Rod Kohi is of immense value to small settlements and such irrigation has been serving as the main occupation and source of food needs. Floods are also a natural means of irrigation for riverine forests and other ecosystems with rich biodiversity such as Manchar Lake, Haleji Lake, riverine ecosystems in D I Khan and D G Khan etc. These have been severely affected due to drought during the last few years.
FLOOD CONTROL OBJECTIVES AND NEEDS
Flood management planning in Pakistan is essentially being carried out to achieve the following objectives:
1. Reduction of flood losses in an economically sound manner,
2. Prioritizing of areas of greater economic hazards,
3. Protecting the cities and vital infrastructural installations,
4. Exploring the possible use of existing flood control facilities,
5. Promoting appropriate land use in flood hazard areas,
6. Minimizing adverse effects on national ecosystem and environment, and
7. Creating flood awareness and adaptability in riverain areas.
Monetary Losses(Billion Rs. at 1955 price level)
Pakistan's rivers are characterized by highly active, meandering channels and moving beds due to the erodible nature of the river plains and variations in the river discharges and sediment concentration. Seasonal floods are also regular features of river flows in Pakistan. Extensive efforts have been made in the past to train the rivers and protect the adjoining areas from river erosion and flood damages. This has mainly been done with the help of a network of embankments reinforced by various types of spurs. To safeguard the areas from inundation, about 5,600 km of embankments have been constructed along major rivers and their tributaries in Pakistan. In addition, more than 600 spurs have been constructed to protect these embankments.
Embankments and Spurs Constructed
|Province||Embankments (km)||Spurs (Nos.)|
|Total in Pakistan||5,595||614|
INSTITUTIONAL ARRANGEMENTS FOR FLOOD CONTROL
Soon after independence, a Central Engineering Authority was constituted to deal with the vast water, power and allied engineering issues at the national level. It was also to serve as an executive body for the execution of several projects. After the creation of WAPDA in 1959, reorganization was undertaken with reduced tasks at the federal level and the Central Engineering Authority was re-designated as the Chief Engineering Advisor's Office with a redefined role.
Up to the end of 1976, the provincial governments were responsible for the planning and execution of flood protection works. The disastrous floods of 1973 and 1976 resulted in heavy losses indicating that the protection facilities and planning at that time were inadequate. In January 1977, the Federal Flood Commission was established. This is the principal institution for flood planning and control in Pakistan. Its mandate includes the preparation of the National Flood Protection Plan, approval of flood control schemes, review of flood damages, plans for reconstruction works, improvements in flood forecasting and warning system, monitoring and evaluation, etc.
Other institutions that play a major role in flood management are PIDAs/ PIDs, WAPDA, Provincial Relief Organizations, Pakistan Army, Pakistan Commissioner for Indus Waters, Emergency Relief Cell and National Flood Forecasting Division.
The major studies undertaken at national level in this sector in Pakistan are:
National Flood Protection Plan I (1977-87) worth Rs. 1.767 billion
National Flood Protection Plan II (1988-98) worth Rs. 7.576 billion
Master Feasibility Studies for Harnessing of Flood Flows of Hill Torrents of Pakistan (1998)
Currently, the Flood Protection Sector Project II is being implemented. The project is worth Rs. 8.0 billion. Its main objectives are to construct flood protection and river training works, improve the weather radar data collection system and create awareness and adaptability among masses.
1. Farhan Sami and Saira Shafi, "Review of the critical problems related to Kalabagh Dam in order to analyse the positive and negative scenarios and develop recommendations for the country", a masters thesis for Environmental Sciences Department, Kinniard College, Lahore, September 2001.
2. Federal Flood Commission, "Annual Flood Report 2001", February 2002.
3. Dr. Bashir A Chandio and Ms Nuzhat Yasmin, "Proceedings of the National Workshop on Water Resources Achievements and Issues in 20th Century and Challenges for the Next Millennium", Pakistan Council of Research in Water Resources, June 1999.
4. Centre of Excellence in Water Resources Engineering, Lahore, "Proceedings - Water for the 21st Century: Demand, Supply, Development and Socio- Environmental Issues", June 1997.
5. Asian Development Bank - TA, Water Resources Sector Strategy, "National Water Sector Profile", April 2002
6. Planning Commission, Govt of Pakistan (September 2001), "Ten Year Perspective Development Plan 2001-11 and Three Year Development Programme 2001- 04".
7. Dr. Nazir Ahmad, "Water Resources of Pakistan", Mirajuddin Press, Lahore, September 1993