African Wildlife and Environment Issue 66

CONSERVATION

CONSERVATION

Engineered wetlands are therefore extremely important. However, any wetland is habitat to a complex set of natural processes. One of the problems with any engineered wetland is predicting how such a systemwill perform. Typically, hydraulic flows through a wetlandwill eventually create a series of preferential pathways as sludge and sediment close out portions with lower velocity flows. Thismeans that themajority of the plants in the system are unable to perform to the desired level when used as an engineered NBS,

conditions, as the basic building block of more complex solutions. Aquatic plants are held in place with a mesh bag enabling the roots to grow into each cell. These roots provide the habitat for microbes that can be specifically selected for a predetermined outcome. Like a printer cartridge that can be replaced when depleted, each cell can be emptied if the roots have trapped hazardous substances that are unable to be metabolized and thus require specialized disposal.

Conservation and environmental management is increasingly dependent on quality Geo-spatial information. While the initial use of maps had political and economic resource exploitation objectives, conservation also requires accurate maps. Geo-spatial information (as in GIS systems) is today an indispensable tool for conservation and management of the environment. One can hardly deliberate on any environmental issue without the relevant information presented, more often than not, as maps. Geo-spatial information for conservation – AN INDISPENSABLE TOOL

Renier Balt & Dirk Pretorius

Prototype Vertical Up flow Modular Engineered Wetland System (VUF MEWS) showing an earlier evolution of the cell placement and root growth. This is a 32-cell unit with a low stacking density. Subsequent evolutions have greatly simplified the design and reduced the cost with higher stacking densities that reduce the total footprint.

New trends and technologies Today many satellite-based datasets are freely available; Google Maps is the best known example and pervasively used. But there are many more that are not that obvious to those outside the industry. Programs backed by large investments from space faring nations make datasets readily available, and often for free. One notable example is the Sentinel Satellite, part of the European Earth Observation Programme , with a budget of €4.3 Billion. Sentinel images are freely available. (apps.sentinel-hub.com/ sentinel-playground/). This provides opportunities for improved conservation management, which up to nowwas only the domain of well-funded specialists in government and large corporations. This article contains examples which demonstrate the diversity of use, and what can be achieved with low cost and available datasets, and affordable GIS platforms. Monitoring of Invasive Species - Water Hyacinth Infestation (WHI) The Hartbeespoort Dam (near Pretoria) is a well known landmark and weekend destination for many outdoor enthusiasts. Unfortunately it is also known for its poor water quality caused by many factors upstream in the tributary rivers. The ‘Metsi-a-Me’ Water Affairs project showed success with the management of remediation of the Hartbeespoort Dam, such as keeping the proliferation of Water Hyacinth at bay. However, in March 2016 Water Affairs terminated the project and the Water Hyacinth Infestation on the dam surface took hold. Growthduring the summermonths of 2016/17 caused coverage of more than 30% of the dam by April 2017 (see fig 1), as the Water Hyacinth population is known to double every 12 days in favourable circumstances. This has serious implications for many people around the dam; it affects recreation and fishing activities, and therefore negatively impacts tourism.

The biodiversity in and around the dam is also negatively impacted, clearly shown by a reduction of about 60% in bird numbers confirmed by the bi annual CWAC count by Birdlife Harties. (CWAC = Coordinated Waterbird Count). The local community in Hartbeespoort responded by setting up a steering committee to direct action plans to improve the situation and to encourage Water Affairs to take up their responsibility again. It is important to monitor the area covered by Hyacinth regularly, in order to measure the size of the problem and also to determine the effect of the mitigation actions. This is done by using Landsat and Sentinel Satellite imagery, and completing analysis available in GIS systems such as Global Mapper™. Between March 2017 and the end of June 2017, a total of 19 cloud-free Sentinel satellite images were available to analyse and monitor. The objective is to reduce the coverage of Hyacinth to 10% after the winter months. At the same time the community will be working towards the re establishment of the Metsi-a-Me project, and for Water Affairs to take up its remediation responsibility.

Conclusion South Africa is once again at the cutting edge of new thinking as the UN is about to mainstream the notion of nature-based solutions in the water sector. The impact of the El Nino drought event has created a window of opportunity for the consideration at policy level of wetland rehabilitation. The emergence of commercially based engineered wetlands simply broadens the scope of such solutions, enabling a greater choice by architects designing green buildings of the future, and users of smaller package sewage plant under increased regulatory pressure to reduce phosphate and nitrate levels in effluent streams being returned to rivers.

simply because preferential pathways bypass the majority of the rhizosphere. This is the working end of such a system, being the clearly defined region of soil horizon fed by nutrients from root secretions and habitat to the microorganisms that metabolize the elements we are trying to eliminate or sequester. The main challenge from an engineering perspective is to bring as much of the rhizosphere into contactwith thewaterweneed to treat usingNBS. This has been done in a recently patented system known as a Vertical Up-flow Modular Engineered Wetland System (VUF-MEWS). This design does away with all substrate, thereby eliminating the major problem of clogging. More importantly, the design optimizes the flow of water being treated through all cells within the module. This means that all wetland plants used in the system will have a reasonably similar flow of nutrients and hazardous elements that need to be sequestered in order to render the effluent safe for re-use. The up-flow dynamic is designed to create a parachute-like formation of habitat for microorganisms. This optimizes the rhizosphere and therefore reduces the footprint of the engineered wetland to manageable dimensions. The modular design means that complex systems can be created from a single fundamental building block, a plastic container with 9 X 6 cells in it. This gives a total of 54 active cells, each with a known set of hydrological

Fig 1: Water hyacinth infestation of the Hartbeespoort Dam 21 June 2017

Anthony Turton Professor: Centre for Environmental Management, Univeristy of the Free State

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