Series No. 7
Approach in Environmental Management
Issues Requiring Innovative Sollutions >
C. Integrated Water Resources
Management and Ecohydrology
Over a billion people worldwide lack access to adequate water, and close
to two billion suffer the consequences of poor sanitation; millions of people
die each year from contaminated water. Water quality, expressed as secondary
pollution and toxic algal blooms, continues to decline in aquatic ecosystems
around the world. Furthermore, thousands of rivers, lakes and reservoirs are
continuously affected directly or indirectly by human activities causing enormous
environmental problems related to biodiversity, ecosystem functioning and preservation
of the water cycle. These impacts are sobering evidence that the prevailing
approach to catchment-scale water management does not guarantee sustainable
water use. Technical approaches to pollution control, such as sewage treatment
plants and regulation of hydrological processes for flood and drought control,
are important but by themselves not sufficient. Purely technical controls,
without understanding and consideration of biota dynamics, reflect a trial
and error approach to water management rather than the implementation of a
policy toward sustainable use of water resources.
In most parts of the world, urbanisation has caused progressive occupation
and development of open land and land reclamation from water basins, causing
changes in ecology and hydrology. Heavy consumption of water in cities, combined
with suburban sprawl resource overexploitation and the technical, political
and economic challenges of meeting water demands, has created growing pressure
to build in new areas and maintain older systems. In developing countries,
providing enough safe water to meet basic human needs is a serious problem.
Areas without adequate water supply tend to remain underdeveloped because of
widespread disease and unsanitary living conditions. Where infrastructure does
exist, water resource managers are struggling to meet more stringent water
quality goals and regulations.
Historically, problems of poor water supply and inadequate wastewater treatment
have persisted because of limited resources and funding, and an absence of
effective policies, planning, management practices and regulations. Even when
funding has been available, the conventional response has been to build large,
centralised treatment plants, often without sufficient consideration of the
need to overhaul and maintain existing supply infrastructure. The potential
for degraded infrastructure to jeopardise safe water supply is often ignored.
For example, it is not unusual for poor distribution systems to leak 50% or
more. Similarly, the construction and operating costs of conventional wastewater
treatment systems are often too high, and much of the world's wastewater is
discharged untreated. As a result, there is growing interest in developing
more affordable, decentralized solutions based on natural systems which combine
natural wastewater purification and nutrient recycling, including the use of
phytotechnologies, such as constructed wetlands, for wastewater treatment.
A watershed planning and management strategy within a hydrologically defined
area provides a coordinating framework for water supply protection, pollution
prevention and ecosystem preservation. Although watershed strategies vary,
they should be based on ecohydrology, the integrated study of ecosystems and
hydrological characteristics and processes and their combined potential to
influence water dynamics and quality. Ecohydrology requires an understanding
of the temporal and spatial patterns of catchment-scale water dynamics which
are determined by four fundamental components: climate, geomorphology, plant
cover/biota dynamics and anthropogenic modifications. A more efficient approach
to water quality and ecosystem integrity requires not only the reduction or
elimination of pollution, but in parallel, an augmentation of the effectiveness
of potential tools to manage the dynamics of excess nutrients, pollutants,
mineral and organic matter in the landscape. This can be done by reducing human
impacts and by regulating the aquatic and terrestrial biota in the catchment.
One of the most efficient ways to control biota dynamics is through the regulation
of hydrological processes by:
||increasing watershed water retention through reforestation
and restoration of land/water ecotones,
||enhancing in-stream retention of water sediments and nutrients
through river renaturisation and wetland restoration,
|| amplifying biogeochemical cycles such as denitrification through wetland inundation.
Recent and ongoing research has greatly increased our understanding of hydrological
dynamics, as well as the biotic and biogeochemical dynamics in freshwater ecosystems
and land/water ecotones. The application of biotic processes can facilitate
self-purification in aquatic ecosystems, significantly reduce the costs of
water quality maintenance, and expand the repertoire of management tools which
can be applied to freshwater resources. The application of ecohydrological
concepts in watershed management also relies on the existence and manipulation
of plants understood in terms of species distribution and interactions.
United Nations Governing Council has directed IETC to play a central role
in the transfer of ESTs for freshwater management in developing countries.
part of this responsibility, IETC is working with the Ecohydrological Programme
of the United Nations Educational, Scientific and Cultural Organization (UNESCO)
and other organisations to promote a broader understanding of the combined
benefits of phytotechnologies and ecohydrological applications.