Inspired by the unique ability of a sponge, which helps it to soak up the water, hold it and then release it when the pressure is applied, engineering and construction experts around the world are planning and working on a brand-new urban construction model known as a ‘sponge city.’
The creation of a sponge city is undoubtedly the best way to turn back to nature to prevent and manage flash floods in urban areas. The infrastructure of sponge cities is based on natural and semi-natural open spaces, which could be used for rainwater harvesting.
Countries like the UK, USA and China have already heavily invested their resources to generalise the concept of sponge cities. They want to protect their major metropolitan areas from submerging into rainwater because of the constantly increasing intensity of heavy downpours due to climate change.
How Does a Sponge City Work?
Most of the construction materials that we use to develop the infrastructure of our cities are unable to absorb water. So, when it pours down, flash floods submerge the urban areas we live in and sweep away everything that comes in their way. But, thankfully, we now have figured out a sustainable and natural solution to prevent such calamities in the form of sponge cities.
To create a sponge city, an urban area is upgraded by adding more greenery and nature, such as different types of plants, trees and artificial and natural water passages. According to this urban construction model, the entire landscape of a metropolitan area should have ample surfaces that welcome rainwater by absorbing it and storing it like a sponge.
The green infrastructure of sponge cities relies on a sustainable drainage system, which is designed to minimise the damage from urban flooding. A useful technique to collect and store water instead of just letting it run off, it is just another form of rainwater harvesting, but at a much, much larger scale.
How Can Your City Be Transformed into a Sponge City?
Pakistan is among the most populous countries in the world. More population means more man-made structures, paved areas and roads and fewer natural places which can absorb rainwater safely. So, instead of going towards costly construction solutions, such as building more barrages, drainage systems, water pumps and dams, Pakistan should also plan out and develop sponge cities. It would also be a good way to promote urban greenery in densely populated cities, especially Karachi and Lahore.
Here’s how any metropolitan area can be transformed into a sponge city
Wetlands
Due to the rapidly increasing urbanisation, the importance of man-made wetlands has grown significantly in recent years. Natural wetlands are marshes, meadows, bogs and natural vegetation with water flowing underneath them.
Man-made wetlands, also known as constructed wetlands, help control the flow of greywater as well as stormwater. They have recently been made an integral part of the infrastructure of sponge cities. The popularity and scale of constructed wetlands have greatly increased over the years and they have become a common occurrence in many different countries across the globe.
Bioswales
Large gutters and storm waters with concrete walls around them may look very unappealing and could ruin the overall appearance of the urban landscape in the surrounding area. Bioswales are an eco-friendly and much more delightful alternative for managing the drainage of water through a bustling city.
Bioswales don’t only allow water to flow through them but they also filter it by removing the pollutants using natural elements. They have unique landscape features that are designed to collect contaminated floodwater, soak it and filter out all the pollution in a very eco-friendly way. Bioswales make use of native plants for the treatment of water and highlight greenery in the city.
Rain Gardens
rain gardens are often confused with bioswales because they have a similar basic mechanism of functioning — but there’s a difference. Bioswales are used to slow down the flow of water and filtrate it, whereas, the purpose of rain gardens is to carry out rainwater harvesting on a large scale by capturing and storing it, chiefly depending on the soil infiltration process.
Rain gardens are planted with deep-rooted vegetation, which facilitates soil infiltration. Designed to safely absorb rainwater, they act like large sponges and are strategically placed in areas prone to urban flooding during the rainy season.
Underground Water Tunnels
Heavy rain spells have become a common occurrence in recent years, wreaking havoc everywhere, especially in countries that are found near the earth’s tropical belt. The construction of underground tunnels is taking place in low-lying areas that are prone to urban flooding.
These water tunnels will facilitate the functioning of sponge cities, aiding to control the flow and store excess rainwater. Sponge cities will have underground water tunnels, functioning underneath a metropolitan area to alleviate any consequences caused by heavy rainfalls and flash floods.
Conservation of Mangrove Forests in Pakistan
The shorelines of Pakistan are blessed with natural sponges in the form of mangroves. They are considered the lifeline for coastal ecosystems and marine animals. Karachi once had an abundance of mangrove forests, which are now diminishing at an alarming rate. The main cause behind these vanishing mangrove forests is increased human activities and pollution.
Mangroves are an important part of the hydrological cycle and their absence could make the situation even worse. There should be public awareness campaigns regarding the restoration of mangroves in Karachi and the surrounding coastal region. They are not only critical to preventing floods in coastal cities but also add to the natural beauty of the shorelines.
Sponge cities are considered among the best solutions to prevent urban flooding — and rightfully so. They promote greenery and natural beauty. Unlike many other man-made structures, it is quite affordable to create a sponge city by upgrading the existing infrastructure with natural elements and different types of horticulture features. On top of that, the entire concept behind sponge cities revolves around environmental sustainability.
So, do you think creating a spongy urban area could solve the problem of urban flooding in your city? Let us know about your thoughts at blogs@zameen.com. In the meantime, stay tuned to Zameen Blog for the most informative lifestyle updates and the best real estate blogs in Pakistan.
