• UNESCO.org/
• Natural Sciences/
• Freshwater/
• IHP/
• Integrated watershed and aquifer dynamics/

• Themes
• Global changes and water resources
• Integrated watershed and aquifer dynamics
• Land-habitat hydrology
• Water and society
• Water education and training
•  

• Worldwide
• 
  
• Africa
• Arab States
• Asia and the Pacific
• Europe and North America
• Latin America and the Caribbean
•  

Integrated watershed and aquifer dynamics

Groundwater flows naturally to the surface through seeps and springs. Invisible at the Earth’s surface, groundwater can be detected by springs coming from rocks, wetland ecosystems and deep-rooted vegetation.

Focal areas

• extreme events in land and water resources management
• international river basins and aquifers
• endorheic basins
• methodologies for integrated river basin management

The aims of this theme

The general aims of IHP activities implemented in the framework of the theme 'Integrated watershed and aquifer dynamics' are:

• to reduce the vulnerability of hydrological systems and improve the efficiency of water management at the basin scale
• to assess the impacts of extreme events and propose mitigation schemes
• to enhance the modeling capabilities of all the relevant processes and fluxes at the interfaces of the hydrological cycle
• to provide a comprehensive assessment of human/watershed/aquifer interactions combining all relevant human activities and physical and ecological processes.

Why aquifer and groundwater management matter

Groundwater is often the primary source for water supplies. It supports agriculture by providing very significant quantities of irrigation water, especially in regions where the climate is dry and crop production without irrigation is not feasible. Groundwater maintains soil moisture, streamflow and wetlands. In arid regions of the world, groundwater is the most important source of freshwater. This theme focuses on the different uses and benefits of groundwater, keeping in mind the following factors.

Groundwater usage

Groundwater usage has increased significantly over the last decades. This is primarily due to its widespread occurrence, overall high quality, reliability during drought seasons, and modest development costs, which are in turn due to advanced drilling and pumping technology.

Economic benefits of groundwater

The development of groundwater has provided great socioeconomic benefits, including enormous public health benefits, due to the consequent decrease in exposure to bacterial and other waterborne diseases. Globally, groundwater is estimated to provide about 50% of current potable water supplies, 40% of the demand of self-supplied industry and 20% of water use in irrigated agriculture.

Outlining the mechanisms that govern water demand

Due to the increased pressure on natural systems resulting from population growth, large regions of the world are now subject to water-related stresses. Consequently, there is a definite need to develop planning and management strategies over larger areas for ecological, social and economic sustainability.

This entails analysing the changing interactions that exist between environmental (climate change, extreme events, desertification), economic (growth of agriculture, industries, energy needs), and social and cultural processes (urbanization, human health) in all of their complexity.

In the hydrological cycle, all the elements of hydrosystems interact, combining, for example, water fluxes with sediment fluxes, as well as nutrients and polluting agents on and below the Earth’s surface. The natural topographic approach is normal for natural hydrological processes, and it is a relevant approach for landscape and land-use mapping because of the topographically driven organization of the typical watershed. But the evaluation of water resources at the larger basin scales needs to combine data from various sources.

This theme of aims to help in the process of better outlining the mechanisms that govern water demand and relevant parameters. Integrated water resource management (IWRM) strategies should recognize the particularities of different water resources or components of the hydrological cycle, approaching their management holistically. Utilizing groundwater sustainably and conjunctively with surface water optimizes benefits and reduces risks for cities, rural communities, agriculture and industry.

Groundwater, a vastly under-valued resource, is one of the keys to solving the world water crisis, but lies hidden out-of-public-sight and therefore out-of-political-mind. It represents 97% of the planet’s accessible freshwater reserves, and currently supplies innumerable farmers, many industries and 2 billion people with their daily water needs, and is also an essential source of water for countless springs and wetlands, for dry-weather flow in the upper reaches of most rivers, and contributes significantly to species diversity in coastal estuaries. In the more arid regions and on small islands, groundwater is often the only freshwater resource. But in many nations, unsustainable groundwater practices are contributing to significant and irreversible damage of the resource base.

In many aquifers, shallow groundwater has been contaminated, the water table has dropped dramatically and the long-term sustainability of the resource has been brought into question. External side-effects include escalating pumping costs, land subsidence, reduced recharge, loss of flow to ecologically important wetlands, and the invasion of aquifers by saline water from estuaries, seas and deep rock formations – problems that may well be compounded by accelerated climate change.