Guest Contribution: Ahmad Ahsan
Torrential downpours flooded huge swaths of Northern Pakistan in July; leading to nearly 50 deaths and damage and destruction to residences, infrastructure, and crops. These rains came atop the monsoon season, which historically has been the harbinger of flooding for decades. Over to the East, monsoon fueled storms and floods have ripped through Nepal, Bangladesh, and India; displacing as much as 5 million people from their homes, and leaving well over 600 dead.
As with the rash of rains we saw in recent days, the factors that fueled flooding have been brewing for years in advance. Extreme rainfall aligns with the impact of climate change. It is crucial to point out that as the average temperature rises, the amount of moisture it can carry also increases. Researchers point out that for nearly every degree centigrade rise in temperature, seven percent more moisture can be absorbed by air. This moisture, in turn, is then released through progressively increasing precipitation.
The stage had been set with the melting of an above-normal snowpack earlier this year. Rains in the first quarter of the year caused rivers to swell, and higher than average temperatures led forecasters to realize that monsoon fueled rains would exacerbate the risk of riverine, urban, and flash flooding, due to isolated extreme precipitation events characterized by localized heavy downpours.
This is evidenced by data from Pakistan Meteorological Department (PMD), which reported above normal precipitation in mountainous areas during winter, followed by above normal rainfall in February accompanied with higher than average temperatures. This trend continued, with temperatures above average by as much as 2oC in March, April, and May; leading to heat wave conditions developing in late May. The monsoon season has also witnessed variations in average temperature by 1oC-2oC. The department warned that warmer temperatures would increase glacial melt, and enhance water flow in rivers.
Irregular rains are likely to stress the cotton crop, and may exacerbate the ongoing drought in Baluchistan and Sindh post-monsoon. Areas of both provinces are expected to face “moderate” drought conditions by PMD. Even worse, these parts of the country may be moving toward a drought-to-deluge cycle, a phenomenon referred to as “Weather Whiplash”, which describes a cycle of extreme weather events rapidly shifting between two conditions.
While no individual weather event can be attributed to climate change, in these things there are signs for those who understand. For example, the duration of heat waves has increased five times over the past three decades, while annual precipitation has shown higher variability and a slight overall increase. Rising temperatures will increase likelihood of heavy rainfall, and the severity of that rainfall, is also on the rise.
The consequences of climate change in the years to come include more extreme floods and droughts, accelerated melting of glaciers increasing the risk of Glacial Lake Outburst Floods (GLOFs). GLOFs occur when ices wall retaining a lake fail, sending humongous volumes of stored water downstream in a devastating flash flood. Pakistan, home to over 2000 glacial lakes, faces GLOF risks in the Kashmir and Khyber Pakhtunkhwa regions where nearly 7 million are at risk. Accelerated glacial melting due to higher temperatures will not only increase the risk of glacial lake outburst flooding in Northern Pakistan, but could potentially alter of river flows, creating a high risk of inundation in densely populated and cultivated areas downstream. Another risk, often overlooked, is sediment deposition, which may increase the risk of flooding even at lower flows.
According to experts, the following years will see increasing rain instead of snow, wide yearly variations in precipitation, and varying intensity and frequency of extreme discharge events. River flood risk may double at the sub-national level within the next two decades, hitting Punjab and Sindh the hardest. Floods are the most common and destructive natural hazard in Pakistan, with 30 major floods having devastated the country over the past 65 years. Flooding has caused historic damages to the country; thousands of lives have been lost, and the economic impact is in the billions. From 1950 to 2016, around 15,000 fatalities were reported from riverine floods.
The 2010 “mega flood” impacted the lives of nearly 20 million people, or 10 percent of the country’s population. The 2010 floods alone are estimated to have caused losses worth $10.5 billion (or 6% of that year’s GDP) in lost productivity due to damages to infrastructure, agriculture, and ecosystem services. During the following 5 years, a major flood event occurred at least once each year; affecting at least 1 million people annually.
Flooding causes direct financial losses due to widespread damage to homes and infrastructure, and loss of livelihoods due to reductions in agricultural, livestock, and business productivity. The impacts on an already overloaded healthcare system, adverse effects on water and sanitation services, disruption of supply chains and public transport, and a host of interlinked social impacts make floods the most expensive natural disaster.
Given the significant damage and disruptions from floods over the past 50 years, Pakistan needs continuous improvement in flood risk management and reduction.
Over the years, major investments have been made to enhance flood protection infrastructure; however, increasing flood hazard risk due to climate change, and the probability of large scale flood exposure due to population growth and economic development necessitate additional protective measures.
These measures include complementing flood protection infrastructure with “soft” measures such as floodplain zoning, improved flood forecasting, and early warnings. Timely warnings during the 2010 flood allowed timely mitigation measures, thereby reducing downstream impact and economic loss. Construction of new reservoirs can help mitigate floods and seasonal flow variations due to climate change. It is crucial to point out that as climate change increases the frequency and intensity of floods, greater investment will be required in the years to come. Increased financing will be required for major infrastructure, reforms and institutional strengthening, urban services, flood mitigation, monitoring, early warning systems, and environmental management. From a legislative standpoint, land-use planning regulations with considerations for flood risk management should be adopted and implemented from the provincial level.
The widespread availability of Information and Communication Technologies, including mobile phones can be used to enhance water data management, modeling, flood risk mapping, and forecasting, at local, provincial, and federal levels. It will also strengthen the monitoring and reporting of water distribution and use; and improve data, modeling, and forecasting to guide preparedness and response to extreme events.
About the author: Ahmad Ahsan is a development sector professional with nearly a decade of experience in monitoring, evaluation, reporting, and communications. He has supported implementation of the World Bank’s Disaster and Climate Resilience Improvement Project and ADB’s Flood Emergency Reconstruction and Resilience Project in Pakistan.