target="_blank" rel="nofollow" href="#ulink_1b765877-5c0b-5fea-b43c-6654a5cf3153">Fig. 1.1 The achievement of sustainable groundwater development through the balance of recharge inputs to aquifer storage (the groundwater resource) against discharge outputs for economic, environmental and human (social) benefits (Hiscock et al. 2002).
(Source: Hiscock, K.M., Rivett, M.O. and Davison, R.M. (2002) Sustainable groundwater development. In: Sustainable Groundwater Development (eds K.M.Hiscock, M.O.Rivett and R.M.Davison). Geological Society, London, Special Publications 193, pp. 1–14. © 2002, Geological Society of London.)
In the second half of this book, Chapters 6 and 7 provide an introduction to the range of field investigation techniques used in the assessment of catchment water resources and includes stream gauging methods, well hydraulics and tracer techniques. The protection of groundwater from surface contamination requires knowledge of solute transport processes, and Chapter 8 introduces the principles of contaminant hydrogeology. Chapter 8 also covers water quality criteria and discusses the nature of contamination arising from a variety of urban, industrial and agricultural sources and also the causes and effects of saline intrusion in coastal regions and oceanic islands. The following Chapter 9 discusses methods of groundwater pollution remediation and protection, and includes sections that introduce risk assessment methods and spatial planning techniques. The final chapter, Chapter 10, returns to the topic of catchment water resources and demonstrates integrated methods for the management of groundwater together with consideration of groundwater interactions with rivers and wetlands, as well as the potential impacts of climate change on groundwater. Given the drive to net‐zero carbon emissions by 2050, the role and interaction of groundwater in the exploitation of energy resources, including renewable resources and shale gas, is reviewed. Finally, Chapter 10 concludes with a description of approaches to groundwater governance and management for the long‐term sustainability of groundwater resources.
Each chapter in this book concludes with recommended further reading to help extend the reader's knowledge of hydrogeology. In addition, for students of hydrogeology, a set of discursive and numerical exercises are provided in Appendix 10 to provide practice in solving groundwater problems. The remaining appendices include data and information in support of the main chapters of this book and will be of wider application in Earth and environmental sciences.
1.2 What is hydrogeology?
Typical definitions of hydrogeology emphasize the occurrence, distribution, movement and geological interaction of water in the Earth's crust. Hydrogeology is an interdisciplinary subject and also encompasses aspects of hydrology. Hydrology has been defined as the study of the occurrence and movement of water on and over the Earth's surface independent of the seepage of groundwater and springs which sustain river flows during seasonal dry periods. However, too strict a division between the two subjects is unhelpful, particularly when trying to decipher the impact of human activities on the aquatic environment. How well we respond to the challenges of pollution of surface water and groundwater, the impacts of over‐exploitation of water resources, and the potential impact of climate change will depend largely on our ability to take a holistic view of the aquatic environment.
1.3 Early examples of groundwater exploitation
The vast store of water beneath the ground surface has long been realized as an invaluable source of water for human consumption and use. Throughout the world, wells and springs fed by groundwater are revered for their life‐giving or curative properties (see Fig. 1.2), and utilization of groundwater long preceded understanding of its origin, occurrence and movement (Bord and Bord 1985).
Fig. 1.2 Lady's Well in Coquetdale, northern England (National Grid Reference NT 953 028). Groundwater seeping from glacial deposits at the foot of a gently sloping hillside is contained within an ornamental pool floored with loose gravel. The site has been used since Roman times as a roadside watering place and was walled round and given its present shape in either Roman or medieval times. Anglo Saxon Saint Ninian, the fifth‐century apostle, is associated with the site, and with other ‘wells’ beside Roman roads in Northumberland, and marks the spot where Saint Paulinus supposedly baptized 3000 Celtic heathens in its holy water during Easter week, 627 AD. The name of the well, Lady's Well, was adopted in the second half of the twelfth century when the nearby village of Holystone became the home of a priory of Augustinian canonesses. The well was repaired and adorned with a cross, and the statue brought from Alnwick, in the eighteenth and nineteenth centuries. Today, groundwater overflowing from the pool supplies the village of Holystone.
A holy or sacred well is commonly a well or spring at which religious devotions are, or have been, practised. In Ireland, for example, there are more than 3000 holy wells, many of which are sites of devotion, especially on the saint's day. Many of these wells have reputations for healing, with commonly cited cures being eye problems, toothache and warts (Misstear et al. 2018).
Springs are significant cultural places, embodying traditional folklore and mythology (Idris 1996; Park and Ha 2012; Powell et al. 2015) and supporting settlements along ancient trade routes (Aldumairy 2005). Indeed, the very survival and dispersal of early hominins, and later Homo, in the East African Rift System may have been influenced by springs. Hundreds of springs and groundwater‐fed perennial streams currently distributed across East Africa are likely to have functioned as persistent hydro‐refugia during dry periods of orbital‐scale climate cycles in the Plio‐Pleistocene and may have facilitated unexpected variations in isolation and dispersal of hominin populations (Cuthbert et al. 2017).
Evidence for some of the first wells to be used by modern humans is found in the far west of the Levant on the island of Cyprus. It is likely that Cyprus was first colonized by farming communities in the Neolithic, probably sailing from the Syrian coast about 9000 BC (Mithen 2012). Several Neolithic wells have been excavated from known settlements in the region of Mylouthkia on the west coast of Cyprus (Peltenberg et al. 2000). The wells are 2 m in diameter and had been sunk at least 8 m through sediment to reach groundwater in the bedrock. The wells lacked any internal structures or linings other than small niches within the walls, interpreted as hand‐ and foot‐holds to allow access during construction and for cleaning. When abandoned, the wells were filled with domestic rubbish which dates from 8300 BC, indicating that the wells had been built at or just before this date (Mithen 2012).
Wells from the Neolithic period are also recorded in China, a notable example being the wooden Hemudu well in Yuyao County, Zhejiang Province, in the lower Yangtze River coastal plain. Based on carbon‐14 dating of the well wood, it is inferred that the well was built in 3710 ± 125 BC (Zhou et al. 2011). The depth of the well was only 1.35 m with over 200 wooden components used in its construction comprising an outer part of 28 piles surrounding a pond, and an inner part, the wooden well itself, in the centre of the pond. The walls of the well were lined with close‐set timber piles reinforced by a square wooden frame. The 28 piles in the outer part of the
