Urban Flash Flooding – Are We Prepared Or Not? Sit Under the Shadow – Urban Flash Flood is Here! Drowning Cities & Rising Vulnerability – Urban Flash Flooding

Floods are the most devastating natural hazard prevailing in Pakistan out of all the natural hazards. Planes of Pakistan often swept across by torrential flooding and the pattern seems to repeat after every 10 years with nothing to be prepared by any governing body of the time. Damages to the life and property after and during flood is colossal and unfortunately, no one do anything to restrain the bulging damages. Floods like riverine floods, flash floods, groundwater flood, drain and sewer flood etc., leave behind damages that require decades to get rehabilitated.
Urban flash flooding is a rising threat to all the main metropolitan cities in Pakistan in the wake of monsoon period that pose serious damages on the urbanized infrastructure. The high magnitude and repeated occurrence of the urban flash floods require intense focus not in the form of policy making but also in effective monitoring and implementation. This article deals particularly with the urban flash flooding in Pakistan, discussing the contemporary challenges of flood risk management and how the institutional framework should work parallel with other stakeholders to lower the damages. Lastly, the article concludes by paving a way for the flood protected urban areas by suggesting resilient combating measures.

Flood Infrastructure in Pakistan

In Pakistan, Major flood infrastructure is not capable of countering the damages by flood and the reasons are multi-dimensional. The major flood protection infrastructure in Pakistan is composed of 6,807 km of flood protection embankments and 1,410 spurs. The responsibilities are given to provincial irrigation departments to maintain their infrastructure. The collaboration of all provincial governments is the need of the hour because when one province or area is affected by the flood the whole country gets effected by it because it harms the economy, infrastructure, health, and shoots many other afflictions.

Currently, Tarbela, Chashma, and Mangla are the main reservoirs that are used to cater to and regulate flood flows during flooding events. These reservoirs are not specified for flood moderation and it is not the first priority because the prime function of these reservoirs is to provide electricity and water for irrigation purposes. Their potential for flood management is not exploited. An effective and efficient flood forecasting and early warning system is necessary to be expanded and modernized. PMD and FFC are working on different flood management projects to make the flood management system more reliable.

Flood Management Challenges

The current Flood Management System in Pakistan is not sufficient to cater the flood damages and is facing many challenges. The legal and institutional framework is the prime requirement to regulate and implement any management or work but unfortunately, there is no flood protection policy currently present in Pakistan. There is a draft Flood Policy exists in Pakistan which seems as a plan rather than a policy. The major content of the policy is dealing with and providing information on riverine floods rather than flash and urban flooding which is one of the major prevailing issues in the wake of climate change. The institutions e.g., NDRRP and NDMA are reactive rather than proactive against flood management.

Flop Institutional Framework

Rampant corruption, poor performance, and lack of institutional capacity are the main reasons for ineffective flood protection and management. Management plans at resource and depression level are effective and sustainable for integration of flood management but unfortunately, no such plan has been prepared and implemented in Pakistan till now.

Deteriorated Flood Infrastructure

In addition, there is also a need to improve the flood infrastructure in Pakistan because the existing infrastructure is outdated since 1850’s. There is no change in the design of the embankment since last decades. The SOPs which are designed and currently implemented at dam and barrages sites are not optimally aligned towards minimizing issues due to flood. Water storage reservoirs are effective against floods but in case of extreme and flash floods, their performance got decreases.
Impoverished Flood Prepared & Emergency Response System

Deteriorated Flood Infrastructure

Flood preparedness system does exist in Pakistan but just in the books, articles, and news. There is no on-ground implementation regarding flood preparedness and the institutions only reacts when the situation gets out of their hands. Various studies have predicted that climate change will affect most of the countries including Pakistan due to flooding, glacier melting, heavy monsoon rainfall. The intensifying impacts of climate change demands for holistic, proactive and stringent policy and its implementation.

Combating the Urban Flash Flooding

Invigorated Local Institutions

The international practices and researches reveal that a viable combination – persistence, good institutions and their enhanced capacity, stakeholders and community participation, women participation, investments in infrastructure improvement, maintenance of drainage system, watershed management, proper land use planning, enhanced institutional capacity, zoning of flood plains, extensive research in identification and marking of flood prone areas, pre and post flood operation study, environment and disaster assessment of all the flood prone areas – is necessary at this stage to combat the impacts of flooding and to protect community from property and life damages. The capacity of institutions who are dealing with the flood protection and management e.g. WAPDA, NDMA, FFC, PMD and Irrigation Departments need to be enhanced.

Imperatives of the Flood Plans

The SOPs regarding flood management at dams and rivers need to be updated by time. A proper plan is required to mark the infrastructure that is coming in the flood route, especially the low-lying areas, villages, towns, and riverside areas. Survey of rivers should be conducted by using modern technologies and software e.g., imageries, digitization, and bathymetric. Flood protection modeling also needs to be done against ongoing and previous floods.

Use of Porous Materials

Since the urban areas are vulnerable to the flash flooding just like other disaster-prone areas. Any manmade structures and surfaces like asphalt absorbs relatively less water and copious rain can easily penetrate in the urban areas water drainage systems. Flash flooding has now become a usual thing after every monsoon due to the more urbanized cities covered in the impervious surfaces. However, the technology has made a way

out of every problem and has given many viable solutions to make life easier. Similarly, a company in UK has made a material Topmix Permeable that can absorb 1,000 liters of water per square meter in a minute.
Topmix Permeable is a fast-draining concrete and absorbs water as if water is getting drained out of a hidden hole. It is a mixture of the road material in which sand or the crushed stone is not added that makes porous to absorbs water. The aggregate sub-base of the crushed stone is placed on the top of soil in which the top most layer is Topmix Permeable.

This made the surface to passthrough water from the top layer then gets collected in the aggregate layer which is then discharged slowly in the ground.

This layer can be installed at the lowest level in the parking lots, sideways, pathways, roads, and more. It helps in reducing flood damages, risk of water shortages, and pressure on the storm water drainage. Acting as a reservoir, it can also be used to retain water table by directing rainwater to the natural aquifers. The multiple layers of Topmix Permeable act as a giant filter for the contaminants like motor oil. However, it is a porous material, it cannot be used completely throughout any road network for heavy traffic that could lead to the fissures in the road.

Flood Water Harvesting

The storage capacity of the river is reduced by siltation and transforming of flood plain areas into permanent habitats. The storage capacity of the rivers needs to be enhanced by sediment management, regulating flood plain land use, mitigation measures identification and implementation. There is a dire need to enhance the water storage capacity by 22 BCM (Billion Cubic Meter) by 2025 to meet the future water and flood management requirements. Reservoir operation manuals should be developed and optimized the flood moderation and other benefits. Pakistan has more than 225 wetlands (covering 780,000 ha of wetlands) which could be preserved to store flood water.

Underground Water Reservoir

Heavy rain can become an affliction instead of a blessing if it is not handled judiciously. For this, there needs to have water conservation strategies to conserve rainwater. It will store the torrential watershed and lower the needs of relying on other sources. Usually, 28,600 gallons is required to water 1 acre of land having 1 inch of water on a weekly basis. A typical underground water reservoir should have the following specifications:

Table 1: Underground Water Reservoir Specifications

The Essentiality of Climate Change with Flood Management Plan
The integration of climate change in flood management is necessary and is internationally recognized that can address flood risks and hazards. Flood management without considering climate change would not be effective rather it may aggravate flood risk. Glacial melting and variability of Moonsoon should be considered. Pakistan’s lack of climate adaptability entails a loss of investment and even human lives. Such losses can be avoided by factoring in climate information into the flood management.
We Need To Be Proactive Than Reactive!
With the rapid shift towards urban areas, coping with the population surge under the haphazard development and crushing climate change patterns, the governing bodies need to act proactively to cater to alter the crooked disaster risk management policies. The robust adaptation and resilient institutional framework are essentially required in collaboration with the planning & development, integrated policy making, and legislation at all the tiers of the public and private sectors. Think tanks like NDMA, PDMA, FFC, WAPDA, MOC, and all the provincial irrigation departments must join hands with other stakeholders in order to ameliorate the policy making efficacy. Eventually, it will help the local bodies to proficiently implement the advance approaches in combating urban flash flooding and shrewdly conserving the rainwater for many other purposes in a smart sustainable way.

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Author:

Tayyaba Akhtar

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