Hydrogeology. Kevin M. Hiscock

Hydrogeology - Kevin M. Hiscock


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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.

      

Photo depicts lady's Well in Coquetdale, northern England.

      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 site may have been part of a shelter for the well, suggesting awareness by the people of the Hemudu culture that their water source required protection (Zhou et al. 2011).

      According to archaeological research, the Chinese are credited with developing the percussion method of well construction, a technique that has been in continuous use now for 4000 years. The ‘rope and drop’ method involved a steel rod or piston that was raised and dropped vertically via a rope supported by a bamboo framework. Using this percussion system with a heavy chiselling or crushing tool, wells were drilled to depths of 130 m around 3000 years ago, although construction took years to complete (Zhou et al. 2011). The cable tool drilling rig used today (see Section 7.2.2) is directly descended from the bamboo framework percussion drilling techniques developed in China.


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