NATURE FOR WATER AND THE ECOHYDROLOGY ACCORD
THE THEME for World Water Day 2018 is ‘Nature for Water’, which explores nature-based solutions to the water challenges of today.
Water access (reliable quantity and high quality) is primary among these challenges. The problems water managers face with the sustainability of water resources (and therefore sustainable development) have stemmed from a growing populous and man’s degradation of the ecosystems’ biological integrity. So much so that we’ve entered the Anthropocence – a geological era where humans are the dominant cause of change in the environment at a global scale.
Water-management efforts must then be focused on managing man’s activities to maintain those ecosystems that are in good health and restoring degraded ones. ‘The answer is in nature’, is a theory by a group of ‘scientist-practitioners’ who evolutionarily established ecosystems functions and services can be restored through manipulation of the hydrological and ecological processes in an ecosystem. This is the ultimate theory of ecohydrology.
Ecohydrology is a trans disciplinary science which uses the understanding of the interplay between hydrological and biological processes (water and nutrient circulation and energy flows) at the drainage basin scale for restoration of ecosystems services for society (Zalewski, 2002).
The ecohydrology approach is based on the idea that all living organisms (biota), from bacteria to fish, to larger vertebrate animals in a watershed have adapted to its hydrological regime (timing and quantity of flows, temperature and its variability), quality, etc., and as such, all flora and fauna living in a particular region of an ecosystem (biotope) have been shaped by hydrology and inversely, biotopes shape hydrology.
The Ecohydrology principles
There are three principles of ecohydrology which are fundamental to the successful implementation of projects: (i) hydrological (knowledge on a river basin’s physical structure, hydrological regime and human-induced impacts at the different hierarchical levels (communities, populations, ecosystem) and at different seasons in time, (ii) ecological (the prospects of augmenting the ecosystem’s carrying capacity) and (iii) ecotechnological (technical capability to manipulate its biological structure and processes to develop novel biotechnological solutions (ecological engineering)).
The latter requires first, that control mechanisms are applied to the former principles so that their paired interaction results in an effect greater than that of their individual (synergy), and second, that ecohydrological methodologies (e.g., phytoremediation, bioremediation), are fused with hydrological engineering (e.g., dams, irrigation systems).
A part of the problem in degraded ecosystems today is that man failed to engineer his infrastructural needs to coexist with nature. A lack of consideration for ecosystems’ response to engineering is evident in reduced water levels (aquifer depletion) threatened biodiversity/invasive proliferation, degraded water quality, etc. The evidence worldwide is impressive. Luckily, there is recognition that we need to train hydrologic engineers to be ecologists (McClain, 2012), that is, to incorporate ecosystems properties in designs, and in more recent times, an environmental component has been a part of formal training in the discipline.
Ecohydrology for sustainable water resources and aquatic ecosystems
The region in general, and Jamaica in particular, is most poised for successful implementation of ecohydrological solutions. This is so as the climatic conditions accommodate the biogeochemical cycles of water, carbon, and nitrogen occurring more rapidly, compared to temperate regions, for instance. Biomass production and hence, biodiversity, is, therefore, easier to restore; the challenge, however, is to retain water in the drainage basin.
Some opportunities for nature-based (ecohydrological) solutions include: Phytotechnologies for industrial and sewage discharges: phytotechnology is an application involving the use of characteristic vegetation to reduce, control, or remove nutrients and contaminants from water and soil. It is typically used for surface and groundwater water quality improvement, wastewater treatment, and restoration of former hazardous-waste disposal sites. A classic example is using reeds tolerant of high nutrients in reed beds of sewagetreatment systems. These plants can be harnessed from flood plains or wetlands. Another example is plants that uptake heavy metals being planted in former red-mud disposal lakes. There is potential for application in Jamaica given the occurrence of proven species and the low initial costs involved. Sustainable Urban Drainage Systems (SUDS) for urban design through municipal management: nature-based solutions in the urban setting or urban ecohydrology, employs ‘soft’ engineering as best management practices (BMPs) under the ‘blue-green’/‘sponge cities’ concept. Emphasis is placed on purification and discharge regulation in the urban landscape. SUDS employ a series of drainage techniques of first controlling flood waters from rain by intercepting water on roofs (green roofs), and diverting surface-runoff to green fields such as detention ponds; pre-treating runoff prior to release to watercourses and aquifers using retention basins and constructed wetlands; delaying the release – runoff retention of surface water and infiltrating water for controlled recharge of groundwater (e.g., vegetated swales). Other methods at the residential level include the use of rain gardens and permeable paving. These mechanisms are said to have not only ecological benefits but also social (recreational, spiritual) benefits. Nature-based solutions such as those mentioned above use ecosystems properties as management tools for ecosystem and societal gain.