Ecohydrology: An integrated and sustainable approach for water resources management in rural areas

Because of pressures generated by an increasing exploitation of natural resources (like soil, water, and vegetation), the entire scientific community is now aware and concerned of the scarcity of these resources and the tight interrelation between technological progress, environmental quality, sustained equity and quality of life. Integrated resource management and sustainable use of resources are important for sustained socio-economic development as a careful trade-off between economic growth and the resulting negative impacts of resource exploitation to fund this growth. Whilst a consensus has emerged that the principle of sustainability should prevail in the management of water resources, there is less agreement about the selection of the appropriate tools to facilitate this sustainable use. The search for appropriate and practical answers to meet these needs no longer relies solely on detailed studies of fundamental hydrological processes, but also requires an assessment of the effects exerted by the space-time evolution of these processes on distribution and functionality of terrestrial ecosystems, i.e. eco-hydrology rather than simply hydrology.Soil and water provide the media for eco-hydrologic processes and mathematical models of different complexity have been developed for describing these processes. Progress has been achieved in advancing scientific knowledge on the soil-vegetation-atmosphere (SVA) continuum as well as in developing improved monitoring and modeling techniques, but difficulties still exist in exploiting these results by decision makers and stakeholders that should plan suitable and effective interventions to protect the ecosystems. Major reasons for that are at least twofold and involve both experimental and modeling issues. Fairly good description of the basic hydrologic processes has been aided at the local experimental level by the availability of accurate measuring techniques and devices. On the other hand, reliable model predictions on the evolution of hydrologic processes are still difficult to achieve, particularly at the space scales of interest for environmental planning.This talk would review and provide a critical account of quantitative analyses of the processes underlying the soil-vegetation-atmosphere (SVA) dynamics. In addressing an issue as complex as prediction of soil-water-vegetation interactions under a specific climate, with its diversity of drivers and processes, it is important an in-depth understanding of the effects of hydrological processes on the structure and dynamics of ecosystems. Water dynamics in the ecosystems is controlled by several nonlinear and interacting processes, which are also characterized by a relatively large spatial and temporal variability. Laboratory and field experiments will be thus reviewed as they represent a valuable basis to throw ourselves toward challenging questions in vadose zone hydrology, such as the “scale-transfer” and model over-parameterization problems, with related problems of parameter non-uniqueness and uncertainty of the simulation. Laboratory experiments on soil cores and columns provide confirmation of theories and enable soil hydraulic characteristics to be identified more accurately. Investigations carried out at plot, transect, and catchment scales provide insights into the hydraulic response of field soils and help in understanding to what extent small-scale measurements provide information about larger scale water flow and solute transport processes. Hydrologic models will be presented and discussed in terms of their parameterization and with a view to their effectiveness with respect to the specific problem being solved.