installation of explanatory panels in the vicinity of the site would promote the sharing of knowledge, the explanation of issues, and benefits and links with society. It is a question of making people understand the technical and biological functioning of the device, but also the issues around the water resource, and the interest of NBSs, and how every citizen can participate in improving trial in practice changes.
1.15.2 South Africa Case Study
It is therefore important that stakeholders understand the necessity of an integrated and tactical tailor-made approach in order to achieve benefits deriving from NBSs. Legislative provision for such an integrated approach to water management is implemented in South Africa. The country’s water legislation (i.e., National Water Act, Act 36 of 1998) provides for the protection of water resources through three main measures, namely:
1 Classification of water resources;
2 Determination of the reserve;
3 Setting of Resource Quality Objectives (RQOs) for the selected class.
These measures specifically address the determination of the level of protection that should be afforded to a water resource to ensure that it continues to function at a certain desired ecological state. However, as shown in Figure 1.12, these measures must also be implemented as part of an iterative process with stakeholders. This iterative approach toward Integrated Water Resource Management (IWRM) as envisaged by the South Africa’s National Water Department, takes into account water availability against water use requirements, which then informs the water balance.
Water classification scenarios are assessed in terms of their economic, social, and ecological implications. The scenarios, in effect, offer different pathways into the future, each representing a different trade-off between water-resource development and use, and protection of the resource. After public consultation, it is the government’s responsibility to decide on what that future will be. This iterative process should ultimately result in a countrywide coverage of catchment management plans, informed by stakeholders’ socio-economic needs and water use requirements. Finally, adaptive management is then considered whereby ongoing management and continuous improvement of the process is achieved through monitoring, evaluation, and enforcement.
Figure 1.12 South African National Water Department’s approach to integrated water resource management, after (King and Pienaar, 201I).
1.16 Ecohydrology, an Integrative NBS Implementation
Ecohydrology is an interdisciplinary science focused on the study and elucidation of feedbacks between water and associated energies fluxes (mainly nutrients and temperature), and aquatic and terrestrial biocenoses (Westman, 1977), their societal roles (Diaz et al., 2006), and the anthropogenic threat to their sustainability [Millenium Ecosystem Assessment (UN, 2005)]. It is in this context that ecohydrology was born as an interdisciplinary science [http://ecohydrology-ihp.org/demosites/] (Zalewski et al., 1997) and conceived as an interdisciplinary science based on the management principle of “dual regulation”, postulating “any action on the flux influences the biota, and any action on the biota influences the fluxes”. Human activities impact both (fluxes and biota), by modifying on the one hand the qualities and quantities of water fluxes and associated substances and, on the other hand, by modifying terrestrial and aquatic biocenoses through agricultural activities and land use, urbanization, and soil sealing, hydraulic developments on water bodies.
1.16.1 Three Nested Logics for Innovative NBS Implementation
In order to optimize currently implemented NBSs and to design new ones, it is necessary to acquire a better knowledge of the functioning of water bodies and to organize them. To do this, it is necessary to theorize the knowledge of eco-hydrological functioning, develop a conceptual model and design new NBSs. Because of the functional coherence inherent to any ecosystem, the functional variations of a water body can be considered as the responses of the structured system to changes according three nested logics: Form-Fluxes-Process logics (see the upper cycle in the Figure 1.13). This functioning model regulates the relationships between the essential disciplines to our integrated approach of ecological functioning in rivers, as for example the self-purification function, by associating geomorphology (form), hydrology (water flow), physical-chemistry (nutrient and pollutant fluxes), and biology (metabolic activities, assimilation, and biodegradation).
Figure 1.13 Logical nesting between levers (actions on forms, fluxes, and biocenosis) for managing NBSs in an anthroposystem governed by laws in force and societal demands.
The different functions identified in Table 1.2 allow us to design the type of installation according to the types of pollution to be treated and their extent. This conceptual model is our framework for integrating knowledge and designing strategies and equipment to mitigate anthropogenic pressure on the resource and preserve ecosystems in highly modified environments.
The model provides a framework for the integration of knowledge and the design of strategies and equipment conceived to mitigate anthropogenic pressure on the water resource and preserve ecosystems in highly modified environments.
It has been integrated in the framework of eco-hydrology to give an operational model allowing action (identification of societal levers of action on the ecosystem). Figure 1.13 also illustrates the double regulation of the ecological state of a hydrosystem, linking our three structuring logics to the two modes of action of society: 1) regulation and measures; and 2) management and actions on the ecosystem, via technologies or methodologies acting on morphology, flows, and/or biocoenosis. The interaction of these three logics leads to the formation of hot spots and hot moments, which need to be located and quantified.
Table 1.2 Interactions between the three nested logics of the aquatic biotope and the different filtering processes (filter effects).
| Filter effects | Three action levels | ||
| Forms | Fluxes | Processes | |
| Mechanical | Screening due to pore size | Feed in particulate matter | Immobilization of particulate micro-pollutants |
| Physical |
| ||
