Sustainable Stormwater Management

By Phumlile Kunene and Annah Ndeketeya

Modern society has brought about rapid urbanization in many areas across the globe. This often comes bundled with various environmental problems, including water pollution mainly due to straining or insufficient service infrastructure; Urban floods are worsened by the high proportion of impervious surfaces and increased stormwater volumes. Stormwater refers to water that flows on the surface after rain. It flows off the land into storm sewers, streams, nearby lakes or rivers. As the rate of urbanization increases, the quantity of stormwater runoff also increases. Several municipalities face significant problems from combined sewer overflowing, contaminating the surface water sources during heavy rainfall events. As stormwater travels over the land, it collects considerable quantities of pollutants such as grease, fertilizers, and pesticides and deposits them in the receiving waters. Citizens and industries also contribute to stormwater pollution by improper disposal of lawn clippings, used oil and littering. These pollutants end up in stormwater drainage systems, creating danger as they become blocked in rainy seasons, resulting in flooding (Kandiah et al., 2017). With these challenges in mind, it is imperative to improve the resilience of water infrastructure to future climate extremes and exogenous factors through sustainable stormwater management.

A stormwater drain blocked by litter in Phomolong, Tembisa, Gauteng.

First and foremost, there is a need to raise awareness and educate communities on reducing damage and protecting the existing drainage infrastructure. There are various strategies that communities can engage in to ensure sustainable management of drainage systems. Doing so will complement the various infrastructure upgrading and rehabilitation programs implemented by the municipalities or responsible authorities. 

Some of the community engagement activities include:

·         Having a proper waste management

·         Replace old stormwater pipes

·         Repair damaged drainage channels.

·         Community surveillance to report illicit dumping and discharges

·         Report damaged drain water systems to the local municipality

Additionally, sustainable drainage systems (SuDS) can be implemented at the property or community level by homeowners, local business owners, churches, schools, and colleges.

 

What is Sustainable Urban Drainage Systems (SUDS)?

Sustainable urban drainage systems are an alternative approach to manage stormwater retention effectively. By definition, SUDS are a suite of technologies and techniques that address urban drainage as part of the natural water cycle through biofiltration, infiltration, groundwater recharge and sustainable storage near the collection point (Fletcher et al. 2015). 

 

Examples of (SUDS) that can be implemented.

Kabrioah irrigation using rainwater harvesting in Kempton Park Source: https://www.sahomesguide.co.za/427-kabrioah-irrigation Rainwater harvesting: A means of rainwater for storage and use for gardening, toilet flushing, and laundry.

Green roof vegetation Life Science the building at the University of the Western Cape main campus Source: https://www.uwc.ac.za/files/images/main-campus-life-sciences.jpg Green roofs: Roof which is covered with an impermeable membrane and a growing medium planted with growing plants

Porous pavement with grass in between the pavement Source: https://www.urbangreenbluegrids.com/measures/porous-paving-materials  Porous pavements: Paved surface which allows free of surface water which then drains directly into the subsoil

Natural wetland with vegetation Source:http://www.spencenursery.com/Index/stormwater_treatment_wetlands.php Natural and constructed wetlands can be effective systems for improving water quality. Wetlands store runoff water in shallow pools that support the growth of plants in the wetland

Source: https://www.slideshare.net/mapistry/municipal-stormwater-program Detention basins/ Dry ponds: Surface storage basin that provides flow control through detaining stormwater for a couple of hours.  Retention ponds/ Wet ponds: An artificial pond with vegetation around and includes permanent water, it is used to store and manage stormwater runoff

Bioswales Source: https://www.owp.csus.edu/lid/site/lot-7-infiltrating-bioswale.html Bioswales allow rainwater to soak into the soil slowly, rather than flooding the streets. They are common along streets or around parking lots. They are vegetated and also serves as biofilters.

  

Benefits of SUDS

• Help manage environmental impacts at the source rather than downstream
• Manage water runoff rates, reducing the impacts of urban generated flooding and damage to property
• Protect and enhance water quality
• Encourage natural groundwater recharge
• Pollution reduction
• Protects health, welfare and safety of the public, property from flooding
• Protects the natural environment
• Provides habitats for wildlife
• Enhance the level of attractiveness of urban areas by green infrastructure
• Contributes to tourism economic activity through pleasing aesthetics for recreational areas and job creation