English Free Article | Water | VOL. 11, ISSUE 65, March-April 2011 |

The Impact of Global Change on Water Resources

The Response of UNESCO’s International Hydrological Programme

The mission of the International Hydrological Programme (IHP) is to strengthen the scientific understanding of the impacts on water systems and to link scientific conclusions to policies for promoting sustainable management of water resources.

The Report provides the context by interlinking the ever increasing population density and per capita resource use over the past century with significant modifications in watersheds, aquifers and the associated ecosystems in terms of vitality, quality and availability of the resource. It also talks about various research activities geared towards finding workable solutions.

Current United Nations predictions estimate that the world population will reach 9 billion in 2050. According to the Report, this exponential growth in population – a major driver of energy consumption and anthropogenic climate change – is also the key driver behind hydrologic change and its impacts. Interconnected issues are: climate change, urbanisation, infrastructural expansion, migration, land conversion and pollution.

While climate change increases the uncertainty associated with the future availability and variability of freshwater resources, which may lead to permanent desertification of certain regions of the world, floods and droughts may have to be managed more frequently now. Added to these exacerbating factors are the direct human induced changes in the local terrestrial hydrologic cycle translating into large cumulative effects on watersheds to river basins and the chronic and progressive depletion and pollution of surface and groundwater reservoirs.

The Report picks up examples from various eco systems such as arid zones, cold environments and permafrost to showcase the efforts that are being put in for examining the impact of global environmental changes on water regimes. In doing so, both water quantity and quality has been talked about. The Report calls for identification of the vulnerabilities and risk assessment relative to the impact and uncertainties, to be able to propose and test adaptation strategies.

Discussing the responses, the Report cites several efforts which deal with assessment and adaptation to impacts brought through global change on freshwater resources. As detailed information is needed to distinguish between natural variability and human influence on reduction or enhancement of low flows and drought, an integrated observation driven approach that confirms the dependencies is required. Climate change affects groundwater recharge and discharge rates, as well as groundwater quality. Since knowledge in this arena is poor, research efforts are underway to better understand the future impact of climate change on groundwater.

The Report through various examples across the globe establishes the interconnections between growing population and soil erosion; urban water, sanitation services and climate change; changes in rainfall patterns, their seasonality and spatial extent and quantity and quality of water resources. In this connection, IHP’s Urban Water Management Programme (UWMP) generates approaches, tools and guidelines which will allow cities to improve their knowledge and analysis.

The lessons learnt during this phase of the programme will be the basis for designing IHP-VIII which will become operational in 2014. Within the new phase of IHP, a hydrological change initiative could serve as an umbrella for existing programmes and bring together all aspects of global change in order to better understand the drivers and their impacts on water resources.

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