Sustainable Solutions for Environmental Pollution, Volume 2. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Биология
Год издания: 0
isbn: 9781119827641
Скачать книгу
Mechanical Screening due to pore size Feed in particulate matter Immobilization of particulate micro-pollutants Physical Surface area to adsorb dissolved compounds Supply in dissolved compounds (pollutants and nutrients) Adsorption of dissolved pollutants Physical-Chemical Chemical reactivity of geological background Supply in TEA, pH buffering and reactive chemical elements Precipitation and physical-chemical redox processes Biological Physical support for microbiocenosis Supply in living microorganisms Biodegradation, assimilation and self-purification

      1.16.2 Ecohydrology on Small Watersheds

      Ecohydrology approach allows, for example, the design of CWs because the knowledge of the dynamics of the processes is defined (Lee et al., 2009). Without wanting to turn water bodies into treatment plants, it is necessary to help them eliminate the pollutants that contaminate them. Bioremediation techniques propose to stimulate natural processes in order to help water bodies to actually or only apparently remove pollutants (they are always present, but hidden).

      However, a third characteristic is to be considered in the spatial management of water flows and associated energies: it is the water path in the different compartments of a watershed. It is useful to have at this stage some pieces of information on the transfer velocities of water and associated substances, both dissolved and particulate, in a watershed. This will depend on the watershed topography, the key determinant of surface runoff and flows, its soil nature which influences the infiltration rate of water into the soil, the land uses which will modify the chemical composition of the water, and the geology which will influence the link between long travel time groundwater and short travel time runoff. It is also necessary to mention the presence of natural bio-catalysts such as bacteria present in the soil, the interfaces of transitions (ecotones) between terrestrial and aquatic environments such as ripisylves and the hyporheic zone (Krause et al., 2017). These multiple interactions give rise to “hot spots” of metabolism at the interface of terrestrial and aquatic environments, in certain places and at certain “hot moments” (McClain et al., 2003).

      Wetlands and temporary streams are a good illustration of the latter. A good knowledge of water paths is therefore necessary to identify places with a high potential for natural metabolism in the catchment area. Water paths on magmatic or metamorphic formation will generally present essentially surface flows with a low quantity of underground water. Land use management along the waterways will then have a preponderant effect on the quality and quantity of water related to rainfall.

      Because the control factors involved in these runoff stages are of different natures and spatial resolution, their respective roles are assessed on a qualitative scale (Lagadec et al., 2016). A scoring method is then used to calculate at which locations in the catchment area the factors contribute most to creating situations with high metabolic potential. The resulting maps are only valid if they are validated by ground truths according to a described methodology (Braud et al., 2020). Intense runoff mappings correspond to heavy rainfall events that are responsible for significant movement of particulate and dissolved matter with runoff and hypodermic flows. We can speak of “hot moment at hot spot”. In comparison, underground flows are slow and contribute above all to the dissolution of matter over time. These dissolved elements are remobilized by exchanges between surface runoff and hypodermic flows where oxidation and reduction reactions are driven by microbiological activity, variations in water content and soil temperature. The identification of metabolism hot spots indicates where in the catchment area the implementation of water and energy flow management strategies would be most effective.

      Runoff is represented by three stages occurring in sequence and be repeated along the slopes before reaching concave topographic breaks, creating local wetlands or contributing to streams flows.

      1 1) The genesis stage, which expresses the potential of an area of the watershed to produce runoff. It can ranked from zero to very high potential;

      2 2) The transfer stage, which indicates flow paths with erosive potential;

      3 3) The accumulation stage, which indicates areas where water and solid deposits concentrate, accumulate and settle on slopes and watercourses.

      The example treated is located in the peri-urban area of Lyon. Comparison with land uses allows the construction