Preface

The dynamics of the inter-relationship between the various elements that constitute a hydrographic basin involve cause-effect relationships that can lead to constant alterations in fluvial dynamics. The combination of elements such as morphology, altimetry, and structural controls in a fluvial network enables a specific longitudinal profile to develop that is dynamic and constantly in search of an equilibrium between the rates of water discharge, erosion, transport, and deposition of sediment.

However, human activities carried out on a stretch of the river may alter this balance in different ways and with different levels of intensity. Indeed, worldwide, the morphology of fluvial systems has been dramatically altered by man's actions. Recent changes in water systems are the result of uses and practices that have been carried out without due care to provide suitable management of the natural resources.

It is widely recognized that the economic, social, and environmental conditions in several hydrographic basins and estuarine systems have changed dramatically in the last decades in consequence of anthropogenic activities, and they will go on changing in the forthcoming years due to increasing human pressure. It is also clear that human activity in these natural systems contributes to global warming and climate change, and it is certain that such consequences will be felt most strongly after the 2050s. Adjustments in natural and human systems are thus necessary to respond to the present-day effects and expected impacts of climate change.

The soils deterioration, changes in landscape structure and functionality, extraction of inert materials, building of hydraulic infrastructures, untreated urban and industrial effluent discharges, and unregulated hunting and fishing activities are all associated with a reduction in the quality of life of riverside populations, forcing us to think about the future in a different way.

Seeking to reverse such a course of degradation, arguments are put forward for development based on the relationship between people and nature, linking activities orientated towards economic dynamism with improvements in the quality of life of local populations, participation in political decision-making, preservation of the natural environment, and concern for the future.

New strategies are needed to develop a multifunctional use structure, which must take into account the multiple aims of sustainable development. Efficient management of water resources necessarily includes measures to strengthen institutions, support for citizen participation, and the development and transfer of technology for this purpose.

To support this development, integrated analyses of new sources of information are needed. In addition, it must be possible to carry out planning scenarios during the decision processes and, for this, we need instruments that assist decision-makers in the search for optimized solutions to existing problems.

Over the past thirty years, Geographical Information Systems (GIS) have developed considerably for Hydrology and Water Resources, and their use now extends far beyond land use planning and thematic geo-referencing for spatial analysis. Indeed, water resource information systems bring together information on quality, quantity, availability, and demand for water, as well as the factors – natural or resulting from human actions – that affect its use.

The data collected must be duly substantiated and remain accessible through a reliable and solid database from a scientific and technical point of view. The systems must also be dynamic in such a way that, on the one hand, they incorporate the information generated by the integrated management system and, on the other hand, they provide the necessary information for the definition of projects, activities, and interventions in river basins.

It must also be recognized that social participation is the most effective way to select the best path to follow in terms of conserving natural resources and guaranteeing their rational and democratic use. For this to happen, it is necessary that social actors and public agents are aware of the role that each must play.

Guaranteeing and exercising social participation are difficult tasks that demand space and adequate mechanisms to ensure that: (1) water management is oriented towards collectively established guidelines and goals, and that (2) projects based on user and community needs and priorities are economically efficient, socially effective, and do not harm the environment.

It is in this overall context that this book emerges, which aims to incorporate different disciplines and approaches, including theoretical analyses, field data, modeling tools, optimization techniques, and economic–ecological instruments in the management of watersheds and estuaries.

Contributions in this book cover the following topics:


I believe this book comprises material of enough quality and quantity to make it a useful reference in the field of river systems.

> **José Simão Antunes Do Carmo** Department of Civil Engineering, University of Coimbra, Coimbra, Portugal
