Hydrogeology. Kevin M. Hiscock
borehole and arrows to the right indicate fluid flowing out of the borehole. Arrows pointing up and down indicate the flow direction in the borehole. The ‘Fractures’ column indicates the interpreted fractures from sonic, electrical potential and calliper logs. The ‘Hydraulic tests’ column shows the test intervals and hydraulic permeabilities from packer experiments during drilling breaks. The ‘Lithology’ column shows the rock types (blue: metasediments; green and orange: ophiolite‐derived serpentinite and skarn rocks; pink: pegmatitic granite). (Source: Adapted from Ahonen et al. 2004.)
Plate 7.2 Automated time‐lapse electrical resistivity tomography (ALERT) monitoring results during an interruption in groundwater pumping in an operational Lower Cretaceous sand and gravel quarry in West Sussex, England. Two times are shown: (a) ta and (b) tb imaged 15 days apart, as well as (c) the log resistivity ratio (tb/ta) plot showing sub‐surface change. Water levels shown are for piezometers P1 and P6. Dashed lines show the minimum and maximum water levels estimated from the log resistivity ratio section (Chambers et al. 2015). (Source: Adapted from Chambers, J.E., Meldrum, P.I., Wilkinson, P.B. et al. (2015) Spatial monitoring of groundwater drawdown and rebound associated with quarry dewatering using automated time‐lapse electrical resistivity tomography and distribution guided clustering. Engineering Geology 193, 412–420.)
Plate 7.3 Satellite‐derived images of (a) shallow groundwater storage and (b) root zone soil moisture content in Europe on 22 June 2020 as measured by the Gravity Recovery and Climate Experiment Follow On (GRACE‐FO). GRACE‐FO employs a pair of satellites that detect the movement of water based on variations in the Earth’s gravity field by measuring subtle shifts in gravity from month to month. Variations in land topography, ocean tides and the addition or subtraction of water change the distribution of the Earth’s mass and gravity field. Measurements are integrated with data from the original GRACE mission (2002–2017), together with current and historical ground‐based observations using a sophisticated numerical model of water and energy processes at the land surface. The colours depict the wetness percentile to illustrate the status of groundwater storage and soil moisture content compared to long‐term records for the month. Blue areas have more abundant water than usual, while orange and red areas have less. The darkest red areas represent dry conditions that should occur only 2% of the time (a return period of about once every 50 years). Much of Europe experienced drought in the summers of 2018 and 2019, followed by little snow in the winter of 2019–2020, the warmest on record. As a consequence, much of the continent began 2020 with a significant water deficit, with the threat of a groundwater drought and implications for maize and wheat yields compared to the five‐year average in a number of countries. (Source: Signs of Drought in European Groundwater, NASA Earth Observatory, https://earthobservatory.nasa.gov/images/146888/signs‐of‐drought‐in‐european‐groundwater?src=eoa‐iotd.)
Plate 8.1 Replica pump with missing handle (see Plate 1b for comparison) in present‐day Broadwick Street, Soho, London. The handle from the original Broad Street pump was famously removed on 8 September 1854 on the recommendation of Dr John Snow (1813–1858) who had concluded that the outbreaks of deaths from cholera among residents of the parishes of St James and St Anne were due to drinking contaminated water from the Broad Street well. From his investigation into the epidemiology of the cholera outbreak around the well, Snow gained valuable evidence that cholera is spread by contamination of drinking water. Subsequent research by others showed that the well was contaminated by sewage from an adjacent cess pool at 40 Broad Street entering the 1.83 m diameter, 8.8 m deep, brick‐lined well sunk in sand above London Clay. This case represents one of the first, if not the first, study of an incident of groundwater contamination in Great Britain (Price 2004).
Plate 9.1 (a) and (b) Location of the Kaibab Plateau in the Colorado Plateau physiographic province (maximum elevation of 2807 m) north of the Grand Canyon, Arizona, United States, including the outline of the Grand Canyon National Park. (c) Shaded relief image of the Kaibab Plateau and surrounding region with approximate locations of major faults in the area. (d) and (e) Two karst aquifer vulnerability maps of the deep (approximately between 650 and 1000 m below ground surface), semi‐confined Kaibab Plateau R (Redwall‐Muav) aquifer system created, respectively, with the original concentration‐overburden‐precipitation (COP) method described by Vías et al. (2006) and the modified COP method of Jones et al. (2019) that uses sinkhole density as well as the location of faulted and fractured rock to model intrinsic vulnerability. Note that the modified model has a reduced overall intrinsic vulnerability to contamination and greater spatial variation of vulnerability (Jones et al. 2019). (Source: Adapted from Jones, N.A., Hansen, J., Springer, A.E. et al. (2019) Modeling intrinsic vulnerability of complex karst aquifers: modifying the COP method to account for sinkhole density and fault location. Hydrogeology Journal 27, 2857–2868.)
Plate 10.1 An example of a dune slack at Winterton Dunes National Nature Reserve on the east coast of Norfolk, eastern England, observed in September 2020. Dune slack (or pond) habitats are a type of wetland that appear as damp or wet hollows left between sand dunes where, as here, the groundwater reaches or approaches the surface of the sand. The unusual acidic dunes and heaths at Winterton are internationally important for the rare groups of plants and animals which they support. The temporary pools in the dune slacks provide breeding sites for nationally important colonies of natterjack toads. The natterjack toad Epidalea calamita is often associated with dune slacks. To breed successfully, natterjacks require warmer water such as found in shallow dune slacks.
Plate 10.2 Multi‐model mean changes in: (a) precipitation (mm/day), (b) soil moisture content (%), (c) runoff (mm/day) and (d) evaporation (mm/day). To indicate consistency in the sign of change, regions are stippled where at least 80% of models agree on the sign of the mean change. Changes are annual means for the medium, A1B scenario ‘greenhouse gas’ emissions scenario for the period 2080–2099 relative to 1980–1999. Soil moisture and runoff changes are shown at land points with valid data from at least 10 models (Collins et al. 2007). (Source: Collins, W.D., Friedlingstein, P., Gaye, A.T. et al. (2007) Global climate projections, Chapter 10. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (eds S. Solomon, D. Qin, M. Manning et al.). Cambridge University Press, Cambridge, pp. 747–846. © 2007, Cambridge University Press.)
Plate 10.3 (a) Map showing global land‐ocean temperature anomalies in 2019. Regional temperature anomalies are compared with the average base period (1951–1980) (Source: NASA (2020). 2019 was the second warmest year on record. https://earthobservatory.nasa.gov/images/146154/2019‐was‐the‐second‐warmest‐year‐on‐record (accessed 13 September 2020).) (b) NASA Goddard Institute for Space Studies (GISS) graph showing global surface temperature anomalies from 1880 through to 2013 compared to the base period from 1951 to 1980. The thin red line shows the annual temperature anomaly, while the thicker red line shows the five‐year running average. (Source: Global Temperature Anomaly, 1880–2013, NASA Earth Observatory, NASA.)
List of boxes
1.1 The aqueducts of Rome
1.2 Groundwater on Mars?
1.3 The North‐west Sahara Aquifer System and the Ouargla Oasis, Algeria
1.4 Groundwater depletion from global irrigated crop production and trade
1.5 Groundwater