Water Wells and Boreholes

Bruce Misstear, David Banks, Lewis Clark

• Editore: Wiley-Blackwell
• Anno: 2017
• ISBN:
  9781118951682
• Edizione: 2
• Argomento: Ciencias físicas
• Categoria: Hidrología

Water Wells and Boreholes focuses on wells that are used for drinking, industry, agriculture or other supply purposes. Other types of wells and boreholes are also covered, including boreholes for monitoring groundwater level and groundwater quality. This fully revised second edition updates and expands the content of the original book whilst maintaining its practical emphasis. The book follows a life-cycle approach to water wells, from identifying a suitable well site through to successful implementation, operation and maintenance of the well, to its eventual decommissioning.

Completely revised and updated throughout, Water Wells and Boreholes, Second edition, is the ideal reference for final-year undergraduate students in geology and civil engineering; graduate students in hydrogeology, civil engineering and environmental sciences; research students who use well data in their research; professionals in hydrogeology, water engineering, environmental engineering and geotechnical engineering; and aid workers and others involved in well projects.

1
Introduction

1.1 Wells and boreholes

Water wells in some form or other have existed for almost as long a time as people have occupied this planet. The earliest wells were probably simple constructions around springs and seeps, or shallow excavations in dry river beds, but such wells have not left any traces for archaeologists. One of the oldest well discoveries is in Cyprus, dating from 7000 to 9000 BC (Fagan, 2011), whilst the earliest well remains in China have been dated at around 3700 BC (Zhou et al., 2011). Since the first millennium BC, horizontal wells or qanats have been widely used for water supply and irrigation in the Middle East and western Asia, notably Iran, and continue to be used today (Figure 1.1). In Europe, the development of many towns and cities in the middle ages and on through the industrial period was aided considerably by the abstraction of relatively pure water supplies from wells and springs (Figure 1.2). In the nineteenth century, new drilling technology was used to construct deep wells to exploit artesian (flowing) aquifers (see Section 1.2 for explanations of aquifer terminology), including the Grenelle well in the Paris basin, which was drilled between 1833 and 1841, and reached a depth of 548 m (Margat et al., 2013). The first mechanically‐drilled well in the United States dates from 1823, whereas the first drilled well in the Great Artesian Basin of Australia was constructed in 1878 (Margat and van der Gun, 2013).

Figure 1.1 Open section of falaj (qanat) running through a town in northern Oman. Here, the channel is divided into three, with two of the channels then rejoining (at the bottom of the picture), in order to produce a two‐thirds: one third split in the flow downstream. This Falaj al Khatmeen is included on the UNESCO list of World Heritage Sites.

Photo by Bruce Misstear

Figure 1.2 Hand‐dug well in Brittany, France.

Photo by Bruce Misstear

Wells continue to have an important role in society today. Some 2 billion people obtain their drinking water supplies directly from drilled or hand‐dug wells (UNICEF and WHO, 2012). A further 4 billion people have access to piped water or public taps, a proportion of which will be sourced from groundwater, so it is likely that more than 3 billion people worldwide rely on water wells for their drinking water. Over half the public water supplies in European Union countries come from groundwater, ranging from between 20% and 30% of drinking water supplied in Spain and the United Kingdom, to nearly 100% in Austria, Lithuania and Denmark (Hiscock et al., 2002).

The largest use of groundwater worldwide is for irrigation (70%), with India, China and the United States the leading countries in terms of total groundwater withdrawals (Margat and van der Gun, 2013). The last 30 years have witnessed a huge increase in the use of wells for agricultural irrigation, especially in Asia (Figure 1.3): in China 54% of irrigation water is supplied from groundwater while this proportion rises to 89% in India and 94% in Pakistan. In the United States, groundwater pumping increased by 144% between 1950 and 1980, with 71% of the annual withdrawal of 111.7 km³ in 2010 being used for irrigated agriculture (Margat and van der Gun, 2013). According to the National Ground Water Association, 44...