Regional and global assessment

Hydrogeological maps present an overview of the hydrogeological conditions in the area concerned, but largely at an exploratory level. Although this is very useful, many tasks at various levels - from local to global - demand more quantitative information, particularly on the quantity and quality of the groundwater resources, on how they relate to other factors and on how they are changing over time. Groundwater resources assessment aims to produce such additional information, usually in the form of extensive and consistent data-sets.

Table 16.2. Existing global, continental and regional hydrogeological maps. (Modified after an unpublished internal document prepared by UNESCO.)

Scale Number

Name (one to x million) of sheets Year Authors

Groundwater in North 1:20 2

and West Africa Hydrogeological 1:8 6

Map of Asia Hydrogeological Map 1:5 1

of Australia

Hydrogeological Map 1:5 2

of the Arab Region and Adjacent Areas Hydrogeology of the 1:2.5 1

Great Artesian Basin

Hydrogeology of 1:13.333 2

North America International 1:5 6

Hydrogeological Map of Africa

International 1:1.5 28

Hydrogeological Map of Europe Les Eaux Souterraines 1:5 dans la Communeauté Européenne Mapa hidrogeologico de 1:5 2

America del Sur Middle East 1:8 1

Hydrogeology The National Atlas of the 1:5 1

United States of America, Principal Aquifers

World Map of 1:10 6

Hydrogeological Conditions and Groundwater Flow Groundwater Resources 1:50 1

of the World a (predecessor of a similar map at scale 1:25 million)

1988 UN/DTDC

1997 Ed. Jiao Shuqin et al.

D.P. and G. Jacobson

1988 ACSAD and UNESCO

1997 Australian Geological

Survey Organization (Habermehl and Lau) 1988/1989 Heath, R.C.

1992 OAU/AOCRS (editor

Safar-Zitoun, M.)

25 sheets BGR and IAH produced by 2003

unpublished BRGM (Margat, J.)

1996 1998

1998

1999 2004

UNESCO/PHI and

Government of Brazil Tübinger Atlas des Vorderen Orients Miller, J.A.

UNESCO, BGR, CGMW, IAEA and IAH (WHYMAP, 2004)

aThe map depicts not only the type of aquifer conditions (hydraulic potential), but also the hydrological potential (recharge class). The 1:50 million version marks in addition the zones in which only saline groundwater occurs.

The role and usefulness of assessment at the level of an aquifer (or part of it) is generally understood and recognized. Hence, assessment is widely practised as a basic step in the development of balanced programmes for groundwater resources development and management. It underpins local actions and enables a better prediction of effectiveness and possible side effects.

Water resources assessment at the national, regional and global levels addresses other needs and often focuses more on policy than on 'action on the ground'. National governments and international organizations want to know the opportunities and problems offered by water in the near future. It allows them to define priorities in their policies and programmes, to allocate budgets and other means accordingly and to decide on which aspects of the political agenda efforts are needed to raise public support. It will be clear that data-sets on selected cases in certain areas - although extremely useful to demonstrate typical concepts and processes - are not enough to satisfy these needs. Full coverage is needed of the territory concerned: a nation, region or even the entire globe. Global water resources assessment is strongly boosted by the WWAP.

In response to the needs for water resources assessment on a global level, FAO has developed its AQUASTAT database on water and agriculture, and UNEP has organized the environmental database of its GEO data portal. Both global databases aim for consistent sets of data on a large number of attributes, defined at the level of countries. FAO's original data are based on enquiries circulated to representatives in the different countries; UNEP's data are being collected by the World Resources Institute (WRI).

The recently established GGIS database of IGRAC (see: www.igrac.nl), intending to bring together all information relevant for groundwater, draws heavily on data from these and other global or regional databases. GGIS not only builds a global database on groundwater-related attributes, but it also provides possibilities for online visualization. One of the GGIS views is 'country-oriented', like the AQUASTAT and GEO databases, and contains 77 standardized attributes. In add ition to these administratively defined spatial boundaries, IGRAC has developed a system of Global Groundwater Regions, in order to organize data according to more physically based units. For this second view, 43 uniform attributes have been defined. The Global Groundwater Regions are depicted in Fig. 16.2. These regions form the highest level in a hierarchical system to delineate physical groundwater units on earth: global groundwater regions - groundwater provinces - aquifers. The global groundwater regions can be subdivided into a number of groundwater provinces; each province encompasses a number of aquifers, which in turn can be subdivided into aquifer beds, and so on. A map of South America's groundwater provinces is shown in Fig. 16.3 for illustrative purposes. A similar map for Australia has been prepared by the Australian Water Resources Council (2004). The added value of GGIS goes beyond bringing together data from different sources and visualizing them; it actively incorporates new data as well.

Programmes like WWAP with its WWDR and UNEP's Global Environment Outlook are heavily depending on data from global databases like AQUASTAT, GEO and GGIS, together with those of the GRDC, GEMS/Water, the GPCC and other global data centres. The quantity, quality and consistency of all these data are still limited. Large efforts are needed to upgrade the databases and the underlying data acquisition programmes.

Fig. 16.3. A map of South America's groundwater provinces. (After UNESCO and CIAT, 2000.)

1: Altiplano 2: Amazonas

S: Andina-Vertiente Atlántico 4: Andina-Vertiente Pacífico 5: Centro Oeste Brasileño B: Costeras 7: Escudo Central

Escudo Meridional 9: Escudo Oriental 10: Escudo Septentrional 11: Orinoco

12: Pantanal-Chaco-Pampeana

15: Patagonia

1B: Säo Francisco

Fig. 16.3. A map of South America's groundwater provinces. (After UNESCO and CIAT, 2000.)

The WWDR and UNEP's Global Environment Outlook present groundwater information in a very broad interdisciplinary context. A recent UNESCO publication on the world's groundwater resources more specifically addresses the needs of groundwater specialists (Zektser and Everett, 2004).

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