An efficient and less expensive technique seems to be working in recharging groundwater and checking flash flood in Pakistan’s capital.
Islamabad, Pakistan’s beautiful green capital, lying in the heart of the foothills of Himalayan mountain range, is facing serious water scarcity issues due to rising population and urbanisation. The civic agencies have managed to implement a groundwater recharging solution with the assistance of local and international organisations to replenish the depleting aquifer of the capital, which is home to scenic biodiversity and wildlife.
The capital city spreads over 906.50 square kilometres (sq km), which includes 220.15 sq km urban and 466.20 sq km rural areas. Back in December 2018, the capital’s groundwater table was found to be depleted alarmingly. Cumulatively, it declined by 85 feet[i] between 2013 and 2017. The population of the city is over 2 million with an annual growth rate of 5.7 per cent[ii]. The population in the urban side makes up its water needs through the Capital Development Authority (CDA) supplies and water bowsers whereas the rural population relies more on private bore wells drilling water at an uncontrolled rate.
According to a study published in Swiss Journal MDPI in 2020 titled “A Comprehensive Index for Measuring Water Security in an Urbanizing World: The Case of Pakistan’s Capital”, there has been an astounding deterioration of water table in the capital at a rate of 1.7 metres per year amid unbridled and illicit pumping of groundwater.
“Water table depletion not only deteriorates the ecosystem but also increases the energy consumption of water pumping in an already energy deficient region,” the study said.
The current per day water demand of Islamabad is estimated to be over 475 million litres per day (MLD) while only 280 MLD is being supplied. The share of groundwater is less than 10 per cent of the total water supply of the city.
Moreover, what aggravates the water scarcity is a reported excessive loss of over 33 per cent because of leakage and unauthorised use in the domestic water supply systems of Islamabad.
Said to be one of the most planned and well developed capitals, Islamabad lacks an effective national policy for the sustainable use of wastewater. On the contrary, the city has only one functional sewage treatment plant at Sector I-9 where less than 20 per cent of its sewage is treated before its disposal.
As a result, during peak summer, amid less rainfall and dropped provisions from the only water supplies of Khanpur and Simli dams, extreme water rationing is being carried out to offset the gap between demand and supply.
“Despite the city’s water supply coverage being 100 per cent, water outage is a common occurrence in Islamabad,” the MDPI study[iii] said.
Recently, a tried and tested technology of groundwater recharge well has emerged as an efficient and less expensive method to cope with the risk of urban flooding through most modern technology available at the local level. Sardar Khan Zimri, deputy director general, Water Management, CDA, is optimistic and convinced with the outcomes of the pilot sites of the groundwater recharge wells. He believes that the artificial groundwater recharge wells have given encouraging results in the pilot phase in July 2022. CDA announced that along with the Pakistan Council of Research in Water Resources (PCRWR), it jointly built 40 underground water reservoirs in Sector I, Sector H, Sector F and Sector G of Islamabad recharged over 8 to 10 million gallons of water on a daily basis during monsoon rainfall.
Keeping in view its optimised benefits, an expedited execution of the technology is underway at the 100 planned sites designated to revive groundwater in the federal capital. “The CDA’s Water Management Wing has proposed a provision in the building by-laws to adopt groundwater replenishing technology at household levels. The higher authority has been suggested to adopt it at the grassroots, community or household level. In case one cannot install at home then it can be done on greenbelts,” Zimri said.
While elaborating the techniques and implementation methods, Zimri said that the well size had been altered during the project implementation owing to the topography of the area. According to him, around 62 wells have been installed so far while 8 to 10 of them failed at Sector F-11, Sector F-9 and Sector G-11 as strata desired was not found.
The civic agency is also assisting schools and educational institutions to install groundwater wells due to scarcity of funds. It is also directing the corporate buildings to adopt the rainwater conserving technology. The groundwater recharge well technology pilot sites in the federal capital include one near Kachnar Park in Sector 1-8 and the other in front of PCRWR offices followed by 100 other sites by the CDA. The CDA‘s 50 recharge wells replenished 10 million gallons of water during the monsoon season of 2022.
The recharge well works conversely to the pumping well as the latter used to extract underground water, whereas the recharge well injects rainwater into the ground through efficient methodology enabling rainwater to soak in the pit through different layers of silica, sand, pebbles and after a filtration process finally enters into the manhole. The recharge well comprises a storm drain, desilting chamber, recharge slab composed of layers of silica sand, gravel, pebbles and a manhole and different inlets.
PCRWR chairman Muhammad Ashraf considers the technology in a different perspective. He believes that the flashfloods are not mitigable in the federal capital or other mega urban centres and they were not even in pre-encroachment scenario of nullahs[iv]. "Watershed management is imperative for flood and drought management whereas the catchment area needed to be widened for trapping more water to improve groundwater reserve. The artificial recharge well's purpose is to capture rainwater near the catchment area and insert it into groundwater well. It will help save water from evaporation, ponding and pollution," Ashraf said.
Saving the aquifers
The PCRWR chairman considers the groundwater recharge solutions as the need of the entire country, especially in the prevailing unprecedented floods in Pakistan. The country is undergoing an eclectic climate catastrophe as drought in one season is followed by devastating floods in the next "We have to increase water storage at every stage. We have to develop large, medium and small dams as per requirement," Ashraf said.
According to him, 60 per cent of water used in agriculture comes from groundwater resources. So either groundwater extraction has to be reduced or the water table has to be recharged. “Groundwater recharge should be an integral part of building by-laws of public buildings including academic institutions, private housing societies and industries.”
A recharging well cost varies from Pakistani rupees PK Rs.50,000 to PK Rs.150,000 based upon the requirement and size of the household and storage capacity. At the moment, the civic agency is bearing the cost through government funding whereas for local level adoption of the solution, the people may pay the amount to get the well established at their houses.
Ashraf recommends protection of recharging zones, separation of storm water and wastewater lines along with the implementation of the “polluter must pay” principle as the thriving housing societies in capital should properly dispose of their solid waste and wastewater. He notes that groundwater regulation is crucial for sustainable management of underground water reserves, whereas mass awareness for water conservation is equally critical to achieve the purpose of water management.
He wrote letters to 43 housing societies in the twin cities of Rawalpindi and Islamabad urging them to build groundwater recharge wells to collect rainwater. However, only two of them responded and showed interest in adopting groundwater recharge well.
Ashraf underscores that the Potohar region comprises the northern part of Punjab province, north-eastern Pakistan, located between the Indus and Jhelum rivers. “It has a complex hydrology that needs to be considered carefully while devising strategies and projects to be adopt for water conservation,” he said.
Mohsin Hafeez, country director and regional representative for Central Asia International Water Management Institute (IWMI), is of the opinion that groundwater is declining sharply in Punjab while water logging is rising in Sindh. The water recharge in the capital, according to Hafeez, was 130-150 mm in 1990. It will remain the same in 2021 but the urbanisation has boomed at a rapid pace.
Interestingly, he said, the rainwater harvesting and recharging well had improved the 4.5 mm water table at Kachnar Park in Islamabad. The Kachnar Park rainwater harvesting well is the only fully instrumented site with an installed water gauge, automatic data drivers that monitor water inflow and temperature shift. The PCRWR teams are doing real time monitoring and collecting hourly data of water collection at the site through solar integrated systems.
From May to September 2022, 78 mm rainfall was recorded at Kachnar Park site that has managed to harvest at least 1.9 million gallons of rainwater. Public response in the success of the recharge wells has been decisive as the community residing along Kachnar Park site has lauded the effort and been very interactive. They have reported that earlier bore wells used to dry up in the summer, which did not happen this time as the water table level was maintained through recharge wells.
The rainwater harvesting initiative has proved to be a promising strategy to control inundation of low-lying areas of the capital as 1.9 million gallons rainwater has been circumvented from deluging Nullah Lai that would have caused flooding otherwise. The PCRWR authorities and experts are working to make the Kachnar Park site as a model stream to be replicated across the country as it can be implemented anywhere including residential or commercial project sites with magnified outcomes.
The Margalla Hills National Park is the watershed area of the capital city that is facing risk of pollution, encroachment, intrusions and ecological damages due to direct dumping of solid and liquid waste into the natural springs of the national park. The Pakistan Environmental Protection Agency (Pak-EPA), in the light of the landmark decision of the Supreme Court of Pakistan, has initiated legal action against the hotels and resorts including other settlements for polluting the national park. The freshwater springs of Margallas feed the channels flowing into the Korang river, and Nullah Lai through an intricate web of small drains mingling in the various sectors of the federal capital.
Experts believe that there is an urgent need for incorporating a mix of integrated approaches from watershed management into policy decisions. On the one hand, the quarters concerned would have to ensure protection and management of watershed area from any disruption or damages and on the other they will have to enact stringent laws that not only penalise the polluters or law abettors but also hold them accountable to ensure compensation for the damage.
[iv] Nullah is a local term used for a riverbed, stream or ravine. In the case of Islamabad, there are numerous small streams or nullahs that feed two rivers – Korang and Sohan – passing by it.