The Provincial Disaster Management Authority (PDMA) has warned of a 30 per cent increase in monsoon rainfall this year across Punjab. Following the first monsoon downpour in Lahore, Chief Minister Maryam Nawaz visited various areas of the city, accompanied by senior government officials, to personally oversee the rainwater drainage operations. This management style mirrors that of the former Chief Minister, now Prime Minister, Shehbaz Sharif.

Nevertheless, the question arises whether this reactive approach, undertaken in a firefighting mode, is sufficient to provide a long-term and sustainable solution for managing rainwater runoff in all major cities, especially given the escalating challenges posed by climate change.

Pakistan is currently experiencing severe impacts of climate change, primarily manifested through rising temperatures, extreme weather events (heatwaves, storms) and intense but brief rainfall spells that result in flooding. The situation demands an adaptive response to climate change, with a strong focus on effective rainwater management.

Rainwater harvesting (RWH) — collection of rainfall from rooftops, elevated land surfaces, or agricultural fields — is an integral component of rainwater management. Many countries, particularly those in water-scarce regions, have adopted RWH to reduce reliance on traditional water resources.

However, unlike those regions where RWH primarily serves for reuse or as a substitute for water sourced from long distances, Pakistan should prioritise RWH to address two critical issues: urban flooding and the rapidly declining water table.

We need a strategy to minimise runoff over roads and use it to replenish our overstressed groundwater reserves

Urban flooding — surface runoff over roads and streets during heavy downpours — has become a severe issue due to recent climate change. Stormwater drainage systems are typically designed with specific water-carrying capacities.

However, when rainfall exceeds these limits, it leads to urban flooding and consequently, cities grapple with standing water, submerged roads, waterlogged streets and choked drainage systems.

This situation not only causes traffic jams and immense inconvenience for residents but also puts an additional burden on the country’s already strained exchequer by spending huge amounts on reconstruction and repairs.

A paradigm shift is essential to address the challenges posed by urban flooding and groundwater depletion. We need a policy-backed, medium-term strategy aimed at minimising runoff onto roads and using it to replenish our overstressed groundwater reserves.

Several effective methods, including storage tanks, urban rain gardens, recharge wells and boreholes, have been widely adopted in various countries.

In 2020-21, the provincial government of Punjab constructed four underground water reservoirs in Lahore, each with a capacity of 1.5 million gallons, to store rainwater runoff from roads and subsequently use it to irrigate roadside plantations and parks.

These reservoirs help alleviate the burden on our drainage systems during rainfall. However, the current number of reservoirs remains inadequate to handle the large volume of rainwater in the city.

Urban rain gardens, which are designed to capture rainwater runoff and allow it to infiltrate the ground and recharge aquifers, were historically practiced in the form of “doongi (deep) grounds”. They still exist in several cities and even in posh housing societies.

These grounds could be made mandatory for new housing colonies, provided they are designed to prevent water from staying longer, thereby preventing them from becoming breeding grounds for dengue mosquitoes.

Several countries, including Australia, Brazil, India, Japan, Sri Lanka, and Taiwan, are gradually implementing regulations to make rooftop RWH (water collected from rooftops) mandatory in certain regions or for specific types of buildings.

Therefore, another option for Pakistan is to enforce similar regulations for public and private buildings — exceeding a certain plot size — in cities to direct collected rooftop water into boreholes and recharge wells to replenish overstretched groundwater resources while simultaneously mitigating urban flooding.

In Islamabad, the Pakistan Council of Research in Water Resources, in collaboration with the International Water Management Institute and WaterAid, constructed fifty artificial groundwater recharge wells in 2021-2022.

Similarly, piloting was undertaken by constructing a few recharge wells in Lahore. The properly designed recharge wells, free from clogging problems, can add a lot of value to reduce runoff water and replenish aquifers.

The agriculture sector accounts for over 90pc of Pakistan’s water usage. In rural areas of Pakistan, groundwater overexploitation — aquifers’ extraction rate exceeds their natural recharge rate, leading to continuous decline in the water table — has become a pressing concern.

In recent years, a surge in indiscriminate groundwater pumping for agriculture has been witnessed due to increased cropping intensity, expansion of highly water-intensive rice cultivation, and a rise in the number of tube wells installed, along with their solarisation. Consequently, water quality is deteriorating rapidly, and the energy requirement for groundwater pumping is continually increasing.

On the other hand, rainwater originating from both urban and rural areas of Pakistan flows across the country, traversing from north to south. As it converges with rivers through drains, it causes floods during the monsoon season.

In this way, millions of acre-feet of precious water, which could be harnessed for various productive purposes, ultimately flow into the Arabian Sea each year — a persistent loss since Pakistan’s independence.

However, agricultural farm-level interventions, using both surface methods (infiltration systems) and deep underground systems (injection methods), are widely used around the world and are viable options for rural areas of Pakistan for artificial recharge of the aquifers and to mitigate floods.

Surface methods rely on small construction works such as ponds, trenches, ditches and grooves, whereas deep underground systems that directly inject collected rainwater into aquifers are based on recharge wells, radial drainage wells, and boreholes.

In conclusion, Pakistan’s per capita water availability has steadily declined due to rising population pressures, inefficient water management practices, and impacts from climate change.

Currently, it stands at a critically low 930 cubic meters per year, placing the country in the category of water-scarce countries. It is high time to implement RWH on a large scale, using a combination of voluntary participation, incentive-based schemes, and mandatory measures.

Khalid Wattoo is a farmer and a development professional and Sara Mehmood is a researcher in climate change, environmental sciences, and forestry

Published in Dawn, The Business and Finance Weekly, July 8th, 2024