Global Change and its Impact on Water Resources: the Role of UNESCO’s International Hydrological Programme

Siegfried Demuth1 and Biljana Radojevic2

1 Head, Hydrological Processes and Climate Section, Division on Water Sciences, Natural Sciences Sector, UNESCO, 1. Rue Miollis 75732 Paris cedex 15, SP France, e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
2 Natural Science Sector, UNESCO, e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Global change is affecting water resources significantly in different parts of the world. Changes in flow regimes combined with changes in precipitation timing and intensity will increase human vulnerability regionally. Livelihoods are affected as climate variability and water stress affect many sectors including agriculture, forestry, health conditions, food production, energy and tourism. The mission of the International Hydrological Programme (IHP) is to strengthen the scientific understanding of these impacts on water systems and to link scientific conclusions to policies for promoting sustainable management of water resources. The influences of global changes on water are playing a significant role in the seventh phase of IHP (2008-2013), entitled “Water Dependencies: Systems under Stress and Societal Responses”. Many IHP programmes such as HELP, FRIEND, IFI, G-WADI, and water quality programme, ISI, the Eco-Hydrology programme, GRAPHIC, Urban Water Management programme, PCCP and the groundwater programme are dealing with global change issues. The scope of the research has also been expanded and covers a diverse range of topics, including low flows, floods, variability of regimes, modelling, tele-connection, process studies, sediment transport, climate change and variability, and land use impacts. The successful accomplishments of the programmes depend on the efficient interaction between its internal management and its external cooperation. This paper provides some insights into some of the programmes dealing with global change and tries to suggest a way forward for international programmes.
Key words: global change, urban water, hydro-hazards, flow regimes, eco-hydrology, water quality, groundwater, conflict solution, adaptation, sediments, climate change and variability.


The management of our water resources is very important for the well-being of livelihoods, the environment and economic development. Water resources are significantly affected by global change and involve more than only climate change. There are few areas of the world where river basins and aquifer systems are not impacted by the numerous other drivers related to human activity. A dramatic increase in urbanization has not only impacts on the landscape but also impacts the runoff processes in the entire basin; especially areas close to river courses and low lying coastal areas are affected. An intensification of agriculture is contributing to deforestation and desertification. Increased water use associated with agriculture and urbanization is leading to changes in storage infrastructure, high rates of groundwater use, and new conveyance networks. Collectively these changes lead to cumulative effects on water quality. Climate change increases the uncertainty associated with the future availability and variability of freshwater resources, and may even lead to permanent desertification of certain regions of the world.
The impacts of floods and droughts in many areas pose an ever greater challenge and risk and will have to be managed now and in future more frequently than in the 20th century. These are exacerbating factors on top of the direct human-induced changes in the local, terrestrial hydrologic cycle that are further translated into large cumulative effects as one moves from watersheds to river basins, and as one looks at the chronic and progressive depletion and pollution of surface and groundwater reservoirs.
Although many countries in the world are affected by these changes which have to be managed at a regional or river basin level, these changes are a global problem; therefore a response to its impacts must also be looked at on an international level. There is no single institution or country which can deal with these global challenges alone, but UNESCO provides a unique cross-disciplinary platform for addressing these issues. It can foster, strengthen and facilitate the necessary international cooperation to bring all major players together, whether they are governments, research institutions, universities, other UN agencies, NGOs, and national or international organizations.

The mission of the International Hydrological Programme (IHP) is to strengthen the scientific understanding of the impacts on water systems and to translate scientific knowledge into policy relevant decisions with the aim of facilitating sustainable management of water resources. The influences of global changes on water are playing a significant role in IHP’s seventh phase (2008-2013), entitled “Water Dependencies: Systems under Stress and Societal Responses”.  Several research activities on assessment and adaptation to global change impacts on freshwater resources have been identified:
  • The development of monitoring networks and databases for change analyses;
  • Methods for change detection, attribution and prediction;
  • Prediction of changes in and vulnerability of groundwater, floods, low flows and droughts ;
  • Assessment of the impact on sediment transport;
  • Prediction of groundwater quality degradation and restoration;
  • Integrated water resources management for adaptation to global change risk;
  • Policy-related interventions for adaptation.
It is therefore important to understand, predict and manage the potential impacts of climate change on regional and global freshwater resources. The impacts of climate change – including changes in temperature, precipitation and sea level rise – are expected to have varying consequences for the availability of freshwater around the world. Climate change impacts the hydrological cycle and thus impacts the management of freshwater resources. Changes in river runoff, for example, will affect the yields of rivers and reservoirs, navigation, and have an impact on the energy sector, finally affecting the recharging of groundwater. An increase in the rate of evaporation will also affect water supply and contribute to the salinisation of irrigated agricultural land. Climate change impacts at all levels are projected to become increasingly strong in the decades following 2025. It is at the national level that the most important decisions need to be made, and adaptation strategies developed. Higher temperatures and decreased precipitation may lead to decreased water supplies and increased water demand with an increase in population.