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

 

On-site sanitation and groundwater contamination

 By Naledi Msiya and Annah Ndeketeya

Sanitation is a vital part of our lives because of its direct impact on public and environmental health. The sustainable development goal (SDG) 6 calls for ‘‘clean water and sanitation’’. However, many developing countries are still lacking in the provision of decent sanitation. The dire sanitation situation is exacerbated by exogenous factors such as rapid urbanization and population growth, leading to many underserviced areas.

One common form of sanitation implemented in African countries is on-site sanitation, which includes facilities such as pit latrines and flush toilets connected to septic tanks. Often, the people in these areas also rely on groundwater for household uses and drinking purposes. Most of these toilets do not meet the design guidelines, and in some cases, community members are not aware of the requirements, such as keeping a safe distance between the septic tank and the groundwater source.

                                                    A picture of a self-made pit latrine in Loskop, Kwazulu-Natal.

 

Without following proper siting and design procedures, the risk to public health is very high because there is a high likelihood of faecal matter and bacteria contaminating the groundwater. Poor water quality can result in water-borne diseases such as typhoid, cholera, dysentery, and diarrhoea. For example, the City of Harare experienced an outbreak of cholera due to water contamination in 2018, and multiple fatality cases were reported (WHO, 2018). Similarly, Zambia also suffered from child fatalities caused by drinking contaminated groundwater (Banda, 2015).

Therefore, proper guidelines must be made available to communities and followed at all times to ensure public safety. Moreover, governments and private entities should invest more in this topic by providing safe water sources and faecal sludge management, frequent monitoring and testing of groundwater quality, and training communities on affordable ways to clean their water before use. In addition to the technical support, more funding should be injected towards affordable sanitation solutions that address location-specific problems.

 

General guidelines for siting and building sanitation facilities

·         On-site sanitation facilities can be used in:

o   Thick soils such as clay layers and soils should have a high organic content to encourage natural denitrification.

o    Climatic conditions should be dry, as wet conditions may support the infiltration of contaminants.

o   On-site sanitation facilities should be located down-slope from the water source

o    Locations with deep aquifers that have very minimal fissures.

•         The recommended minimum distance between the toilet and groundwater source is 15-30 m (Graham, Matthew & Polizzotto, 2013).
•        Pit latrines can be constructed at an elevated area or lined to reduce the chances of contamination (Graham et al., 2013). Residents can also get support and information from local WASH non-governmental organisations (NGOs) and International development organisations such as WHO.

The current threat of Covid-19 on groundwater resources

Recent studies have shown that the coronavirus (Covid-19) can remain present in human faeces for up to 33 days (Huo et al., 2021). However, no evidence has been submitted so far for faecal−oral transmission of the COVID-19 virus. On the other hand, the best way of preventing Covid-19 is through frequent washing of hands. Of course, this requires access to clean water, which might not be available in these vulnerable communities. Hence, urgent measures are needed to help such communities cope with the pandemic and have clean water available for clean washing.

·         Some of the affordable water purification solutions to consider include:

•       Boiling the water before drinking
•          Treatment by Chlorination using chlorine tablets or bleach
•           Biosand Filtration
•          Ceramic filters
•      Solar sterilization and solar distillation

 

 

 

 

 

 

 

Celebrating Women in Water

Today, we celebrate International Women's Day. I especially would like to extend my warmest regards to all Women in Water. Kudos to you, and may you keep working hard towards sustainable and equitable access to safe water supply and sanitation services. 

Women play different roles in the water sector. This includes the traditional chore of fetching water to ensure that the family has enough for cooking, drinking, bathing, laundry and gardening; and professional roles such as water engineers, water researchers, policy, environmentalist, hydrologists, environmentalists, managers, just to mention a few. 

This year's call for change is driven by the campaign theme "Choose to challenge".  this can be achieved by:

• Calling out on unequal access to water and sanitation services
• Help forge inclusive enrolment in STEM subjects in Higher education institutions
• Help remove barriers to female employment in the water sector
• Remind the world that Women deserve a place at the decision-making table
• Sharing women in achievements
• AND much more!

Join the campaign today!

If you are a woman working in the water sector and would like to connect with other women professionals to share experiences and ideas, you can join the Community of Women in Water (CWiW), a global networking platform supporting women working to solve water issues!

I would also love to connect with other young women professionals. Check out my LinkedIn profile. 

Celebrating Wetlands!

 The 2nd of February was World Wetlands Day. 

This is a day set to celebrate and appreciate the beautiful habitats. It also serves to remind us that we need to conserve and protect this vital natural resource. 

So, what exactly is a wetland?

According to UNESCO, "wetlands are ecosystems seasonally or permanently saturated with water. This can include all lakes and rivers, underground aquifers, swamps and marshes, wet grasslands, peatlands, oases, estuaries, deltas and tidal flats, mangroves and other coastal areas, coral reefs, and all human-made sites such as fish ponds, rice paddies, reservoirs and salt pans". 

What is the value of wetlands?

• Promote biodiversity - wetlands are home to many plant, fish and wildlife species.
• Water purification - wetlands plants remove pollutants through sediment trapping, nutrient removal and chemical detoxification. 
• Water storage- wetlands are often referred to as natural sponges because of their ability to soak up water during high runoff periods and release it slowly into the ground. This helps control the severity of floods and erosion.
• Their ability to recharge groundwater helps in addressing water scarcity issues.
• Wetlands may reduce risk to public safety and damage to property due to flood water or stormwater runoff.
• They offer recreational and economic benefits through hiking, boat rides, fishing, bird watching, canoeing and photography. 
• Provide products for home use and crafts, including fuelwood for cooking, fish, wild rice and fruits for food,  reeds for weaving baskets and mats,  thatch for roofing, fibres for textiles and papermaking, and timber for building. Medicines can be extracted from tree barks, leaves, and fruits, and the plants also provide tannins and dyes. 
• The diverse and abundant vegetation and animal species give wetlands a high aesthetic value. These visually rich environments usually attract people to see wildlife, have picnics and capture nature's beauty through the camera lenses. 
• Wetlands provide opportunities for education, research and innovation. Researchers can study the historical changes in climate and vegetation over thousands of years, which can help develop future solutions. Also, by studying and understanding the functioning of wetlands, new solutions to engineering and design can be drawn, e.g. through biomimicry.  

How can we conserve wetlands?

Wetlands are often under threat from many human activities, and it takes everyone's effort to ensure that the wetlands are safe and protected. This can be done by:

• Not dumping waste in wetlands
• Not cultivating in wetlands
• Not building and settling in wetlands
• Adopting a wetland stream as a community or school and closely monitor and protect it 
• Raising awareness in your community, school and university
• Guard and being vigilant against any element that could threaten the existence and functionality of wetlands
• Avoid overutilization of wetland resources