1.6 NASA Landsat‐7 satellite image of the Ouargla Oasis, Algeria on 20 December, 2000. In this false‐colour image, red indicates vegetation (the brighter the red, the more dominant the vegetation). Pale pink and orange tones show the desert landscape of sand and rock outcrops. The satellite image shows date palms surrounding the urban area of Ouargla and Chott Aïn el Beïda in the south‐west, a saline depression that has traditionally collected irrigation runoff, as well as the proliferation of irrigated land to the north and east of Ouargla in the vicinity of Chott Oum el Raneb. The width of the image shown is approximately 40 km. (Source: Reproduced from http://earthobservatory.nasa.gov/IOTD. NASA images created by Jesse Allen and Rob Simmon, using Landsat data provided by the United States Geological Survey. Caption by Michon Scott.)
Plate 1.7 Estimated depth in metres below ground level (m bgl) to groundwater in Africa (Bonsor and MacDonald 2011). (Source: Bonsor, H.C. and MacDonald, A.M. (2011). An initial estimate of depth to groundwater across Africa, 2011, British Geological Survey. © 2011, British Geological Survey.)
Plate 1.8 Aquifer productivity in litres per second (L s−1) for Africa showing the likely interquartile range for boreholes drilled and sited using appropriate techniques and expertise (Bonsor and MacDonald 2011). (Source: Bonsor, H.C. and MacDonald, A.M. (2011). An initial estimate of depth to groundwater across Africa, 2011, British Geological Survey. © 2011, British Geological Survey.)
Plate 2.1 Aerial view of artesian springs and spring mounds west of Lake Eyre South (137 °E, 29 °S) in the Great Artesian Basin in northern South Australia (see Box 2.11) showing the flowing artesian Beresford Spring (A in foreground), the large, 45 m high Beresford Hill with an extinct spring vent (C), the flowing artesian Warburton Spring (E), and the flat topped hill (F) capped by spring carbonate deposits (tufa) overlying Bulldog Shale. The diameter of the upper part of the circular Beresford Hill, above the rim, is about 400 m. Luminescence ages of 13.9 ± 1 ka were determined for samples from the carbonate mound of the actively flowing Beresford Spring (B) and of 128 ± 33 ka from the north west side of the dry extinct Beresford Hill spring carbonate mound deposits (D) (Prescott and Habermehl 2008). (Source: Prescott, J.R. and Habermehl, M.A. (2008) Luminescence dating of spring mound deposits in the southwestern Great Artesian Basin, northern South Australia. Australian Journal of Earth Sciences 55, 167–181. Reproduced with permission from Taylor & Francis.)
Plate 2.2 Big Bubbler Spring, with its spring outlet on top of an elevated mound, located west of Lake Eyre South in the Great Artesian Basin in northern South Australia (see Box 2.11). The spring outflow runs into a small channel and forms small wetlands (to the right). Hamilton Hill and its cap of spring carbonate deposits is visible in the background and is similar to Beresford Hill (Plate 2.1) located approximately 30 km to the north‐west (Prescott and Habermehl 2008). (Source: Prescott, J.R. and Habermehl, M.A. (2008) Luminescence dating of spring mound deposits in the southwestern Great Artesian Basin, northern South Australia. Australian Journal of Earth Sciences 55, 167–181. Reproduced with permission from Taylor & Francis.)
Plate 2.3 1 : 50 000 000 Transboundary Aquifers of the World (Special Edition for the 7th World Water Forum 2015) map. There are 592 identified transboundary aquifers, including transboundary ‘groundwater bodies’ as defined by the European Union Water Framework Directive, underlying almost every nation. Areas of transboundary aquifer extent are shown with brown shading and areas of transboundary groundwater body extent are shown with green shading, with overlapping aquifers and groundwater bodies shown in gold shading. Individual blue squares and green circles, respectively, indicate small aquifers and groundwater bodies (<6000 km2). The thematic inset maps combine, from left to right, respectively, the delineations of transboundary aquifers of the world with maps of climate zones, groundwater resources and recharge, and population at 1 : 135 000 000. For more information on individual transboundary aquifers and groundwater bodies and an extended view of the small aquifers and groundwater bodies, visit IGRAC’s online Global Groundwater Information System: (https://ggis.un-igrac.org/ggis-viewer/viewer/tbamap/public/default). (Source: Transboundary Aquifers of the World, Special Edition for the 7 World Water Forum 2015, IGRAC. © 2015, IGRAC.)
Plate 2.4 Groundwater discharge in the intertidal zone of Kinvara Bay on 15 September 2010 at Dunguaire Castle, County Galway, Ireland.
Plate 2.5 Lake Caherglassaun (for location see Box 2.14, Fig. 2.66) responding to high tide as observed at 14.53 h on 13 September 2006 in the karst aquifer of the Gort Lowlands, County Galway, Ireland.
Plate 2.6 The Carran Depression and turlough (a fluctuating, groundwater level‐controlled ephemeral lake) on 13 September 2006, The Burren, County Clare, Ireland.
Plate 2.7 1 : 25 000 000 Groundwater Resources of the World (2008 edition) map showing the distribution of large aquifer systems (excluding Antarctica). Blue shading represents major groundwater basins, green shading areas with complex hydrogeological structure and brown shading areas with local and shallow aquifers. Darker and lighter colours represent areas with high and low groundwater recharge rates, respectively, generally above and below 100 mm a−1. For further discussion see Section 2.17. (Source: Wall map “Groundwater Resources of the World”, Global groundwater wall map, 2008. © 2008, WHYMAP.)
Plate 2.8 1 : 120 000 000 Groundwater Recharge (1961–1990) per Capita (2000) map showing groundwater recharge in m3 capita−1 a−1 aggregated for countries or sub‐national units (excluding Antarctica). (Source: Wall map “Groundwater Resources of the World”, Global groundwater wall map, 2008. © 2008, WHYMAP.)
Plate 3.1 Variable‐density groundwater flow simulations to evaluate the efficiency of different styles of salinization processes in layered aquifer systems on the continental shelf during and after transgression of the sea (see Section 3.6.1 and Fig. 3.12). The upper panel shows the model set‐up representing a slightly seaward dipping layered aquifer system in which the left‐hand boundary represents fresh, meteoric water originating as recharge in the hinterland. The right‐hand boundary represents coastal seawater. In the initial steady‐state situation (t = 0 years), the sideways sag of the saline water underneath the sea floor results in a tongue of saline water in the deeper inland aquifers. When sea‐level rises, seawater starts to sink into the upper aquifer with a characteristic finger pattern indicative of free‐convection replacing fresh water. This process of salinization is rapid compared to the salinization process in the deeper aquifer which only proceeds slowly by transverse movement of the saline‐fresh interface. The simulation shows that it takes millennia for these processes to result in complete salinization of sub‐seafloor aquifers which explains the current occurrence of fresh water in many parts of the continental shelf (e.g Fig. 3.13).
Plate 3.2 Example of a numerical simulation illustrating aspects of the hydrodynamics within sedimentary basins during glaciation. (a) A bowl‐shaped sedimentary basin is conceptualized consisting of several thick aquifers and aquitards. This basin is overridden by an ice‐sheet, which results in a complex hydrodynamic response. A deformation of the finite‐element mesh accommodates the flexure of the sedimentary basin caused by the weight of the ice‐sheet. (b) The high hydraulic head at the ice‐sheet base is propagated into the aquifer units in the basin and results in a strong groundwater flow component away from the base of the ice‐sheet. At the same time, the increasing weight exerted as the ice‐sheet advances results in a build‐up of hydraulic head in the aquitard units in the basin which is considerably more compressible than the aquifers. Consequently, groundwater
