Groundwater development techniques - Revision history

Dbk: Removed protection from "Groundwater development techniques"

2023-11-28T14:35:47Z

Removed protection from "Groundwater development techniques"

← Older revision		Revision as of 15:35, 28 November 2023
(No difference)

Beod: Blanked the page

2019-05-07T16:07:31Z

Blanked the page

Show changes

Beod: /* Links to more information */

2019-03-06T12:27:22Z

Links to more information

← Older revision		Revision as of 13:27, 6 March 2019
Line 101:		Line 101:
	World Health Organisation. 2011. [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ Guidelines for drinking-water quality, 4th edition]. ISBN: 978 92 4 154815 1		World Health Organisation. 2011. [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ Guidelines for drinking-water quality, 4th edition]. ISBN: 978 92 4 154815 1

	[[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> [[Developing groundwater resources \| Developing groundwater resources]] ~~>> Groundwater Development Procedures~~
			Return to: [[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> [[Developing groundwater resources \| Developing groundwater resources]]

	[[Category:Additional resources]]		[[Category:Additional resources]]

	[[Category:Africa Groundwater Atlas]]		[[Category:Africa Groundwater Atlas]]

Beod at 16:45, 9 January 2019

2019-01-09T16:45:21Z

← Older revision		Revision as of 17:45, 9 January 2019
Line 46:		Line 46:
	\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to collect good data.		\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to collect good data.
	\|-		\|-
	\|Designing and constructing suitable boreholes:		\|Designing and constructing suitable boreholes. The design of every borehole should be adapted to the particular geology found at the drilling site, based on the information collected during drilling. An introduction to some types of borehole design that are suitable for many hydrogeological environments found in Africa can be found in the chapter [https://www.developmentbookshelf.com/doi/abs/10.3362/9781780441290.006 '''Designing and constructing water points'''] in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)], which can be freely downloaded online.
	\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to ~~supervise~~ the ~~drilling and collect good data~~.		\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to design the final borehole construction.
	\|-		\|-
	!colspan="4"\|Borehole Testing		!colspan="4"\|Borehole Testing

Beod at 16:11, 9 January 2019

2019-01-09T16:11:40Z

← Older revision		Revision as of 17:11, 9 January 2019
Line 22:		Line 22:
	\|'''Stage'''\|\|''' Notes on costs'''		\|'''Stage'''\|\|''' Notes on costs'''
	\|-		\|-
	!colspan="4"\|[[Siting Boreholes \| Siting Boreholes]] ~~or Wells~~		!colspan="4"\|Project Management
			\|-
			\|Project management is an essential part of projects to develop groundwater. A borehole drilling project can include sensitisation of and training of end users; borehole siting, design, drilling, development and completion; borehole testing (yield and water quality); and pump installation. Each part needs to be professionally run if it is to be successful. RWSN provide guidance in this area, including this guide to [http://www.rural-water-supply.net/en/resources/details/431 Procurement and Contract Management of Drilled Well Construction].
			\|\|An experienced project manager may be needed to oversee a borehole drilling project.
			\|-
			!colspan="4"\|[[Siting Boreholes \| Siting Boreholes]]
	\|-		\|-
	\|[[Siting Boreholes:Reconnaissance \| '''Reconnaissance''']]: gathering maps and information (e.g. from existing reports, academic papers etc) on geological and hydrogeological conditions. This is an essential first step for understanding groundwater resources.		\|[[Siting Boreholes:Reconnaissance \| '''Reconnaissance''']]: gathering maps and information (e.g. from existing reports, academic papers etc) on geological and hydrogeological conditions. This is an essential first step for understanding groundwater resources.
Line 35:		Line 40:
	!colspan="4"\|[[Borehole Drilling \| '''Borehole Drilling''']]		!colspan="4"\|[[Borehole Drilling \| '''Borehole Drilling''']]
	\|-		\|-
	\|[[Borehole Drilling \| '''Collecting information during drilling''']]: gathering information on geology (e.g. from logging drilled rock chips and measuring penetration rates) and hydrogeology (e.g. from water strikes). ~~Borehole drilling~~ is a unique opportunity to collect useful geological and hydrogeological data from deep underground - data that are not otherwise available.		\|[[Borehole Drilling \| '''Drilling Supervision''']]: experienced supervision of drilling is essential for the provision of successful and long-lasting water boreholes.
			\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to supervise the drilling.
			\|-
			\|[[Borehole Drilling \| '''Collecting information during drilling''']]: gathering information on geology (e.g. from logging drilled rock chips and measuring penetration rates) and hydrogeology (e.g. from water strikes). Drilling is a unique opportunity to collect useful geological and hydrogeological data from deep underground - data that are not otherwise available.
			\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to collect good data.
			\|-
			\|Designing and constructing suitable boreholes:
	\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to supervise the drilling and collect good data.		\|\|A well-trained hydrogeologist or engineer should be onsite during drilling to supervise the drilling and collect good data.
	\|-		\|-

Beod at 14:46, 9 January 2019

2019-01-09T14:46:14Z

← Older revision		Revision as of 15:46, 9 January 2019
Line 1:		Line 1:
	[[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> Groundwater Development Procedures		[[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> [[Developing groundwater resources \| Developing groundwater resources]] >> Groundwater Development Procedures

	This page is still in development - please check back soon for updates.		This page is still in development - please check back soon for updates.
Line 90:		Line 90:
	World Health Organisation. 2011. [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ Guidelines for drinking-water quality, 4th edition]. ISBN: 978 92 4 154815 1		World Health Organisation. 2011. [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ Guidelines for drinking-water quality, 4th edition]. ISBN: 978 92 4 154815 1

	[[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> Groundwater Development Procedures		[[Africa Groundwater Atlas Home \| Africa Groundwater Atlas]] >> [[Additional resources \| Resource pages]] >> [[Developing groundwater resources \| Developing groundwater resources]] >> Groundwater Development Procedures

	[[Category:Additional resources]]		[[Category:Additional resources]]

	[[Category:Africa Groundwater Atlas]]		[[Category:Africa Groundwater Atlas]]

Beod at 17:08, 8 January 2019

2019-01-08T17:08:23Z

← Older revision		Revision as of 18:08, 8 January 2019
Line 27:		Line 27:
	\|\|A one-off cost: several weeks time of a project staff member or consultant. If new data have to be bought or generated (e.g. from satellite images or field mapping), costs will increase, but not prohibitively so.		\|\|A one-off cost: several weeks time of a project staff member or consultant. If new data have to be bought or generated (e.g. from satellite images or field mapping), costs will increase, but not prohibitively so.
	\|-		\|-
	\|'''Hydrogeological fieldwork''': making field observations of the local geology (e.g. from rock exposures or chippings/cuttings from any local hand-dug wells or previously drilled boreholes); hydrogeology; and existing water sources (both dry and wet season sources), and gathering relevant information from discussions with the local community: e.g. how much do existing sources yield; do yields fall or dry up in the dry season; are there water quality problems? Also observe any local pollution sources, such as pit latrines, burial grounds, cattle pens or market areas. This should be done by someone experienced (e.g. who has developed boreholes in this area, or similar areas, before).		\|[[Siting Boreholes \| '''Hydrogeological fieldwork''']]: making field observations of the local geology (e.g. from rock exposures or chippings/cuttings from any local hand-dug wells or previously drilled boreholes); hydrogeology; and existing water sources (both dry and wet season sources), and gathering relevant information from discussions with the local community: e.g. how much do existing sources yield; do yields fall or dry up in the dry season; are there water quality problems? Also observe any local pollution sources, such as pit latrines, burial grounds, cattle pens or market areas. This should be done by someone experienced (e.g. who has developed boreholes in this area, or similar areas, before).
	\|\|Requires a well-trained engineer or hydrogeologist to visit the area.		\|\|Requires a well-trained engineer or hydrogeologist to visit the area.
	\|-		\|-

Beod at 17:06, 8 January 2019

2019-01-08T17:06:46Z

← Older revision		Revision as of 18:06, 8 January 2019
Line 47:		Line 47:
	\|}		\|}

	==~~Types of groundwater sources~~==		==Groundwater source types==

	~~Groundwater can be abstracted from the ground in different ways. Many resources~~ are ~~available to support the choice of which abstraction method to use in different environments~~ - ~~there~~ are ~~some references at the bottom of this page~~.		The most common groundwater source types are '''springs''', '''hand-dug wells''', or drilled '''boreholes'''. (Drilled boreholes are often also called wells!).

	~~Groundwater is most often accessed through '''springs''', '''hand-dug wells''',~~ or ~~drilled~~ '''~~boreholes~~'~~''. (Drilled boreholes are also sometimes called wells!)~~.		Many resources are available to support the choice of which groundwater source type to use in different environments or for different purposes. Some of these are shown in the section ''Links to more information'' at the bottom of this page.

	* '''Springs''' are natural flows of groundwater from the underlying rock or unconsolidated sediment. Springs are dependent on the characteristics of the rocks, and their nature and yields are hugely variable. They often occur in specific hydrogeological environments. Because they are open at their source, springs are vulnerable to contamination. No equipment is needed to make a spring, but springs can be improved and made less vulnerable to contamination and drought by various developments, such as constructing a collection tank to store spring water, and installing a protective cover over the spring head.		*'''Springs''' are natural flows of groundwater from the underlying rock or unconsolidated sediment. Springs are dependent on the characteristics of the rocks, and their nature and yields are hugely variable. They often occur in specific hydrogeological environments. Because they are open at their source, springs are vulnerable to contamination. No equipment is needed to make a spring, but springs can be improved and made less vulnerable to contamination and drought by various developments, such as constructing a collection tank to store spring water, and installing a protective cover over the spring head.

	* '''Hand-dug wells''' have been dug to access groundwater for thousands of years. They can only be dug in soft material, such as unconsolidated sediment like sand and gravel, weathered basement, or limestone. They are only appropriate where the groundwater level (water table) is shallow. They are usually less than 20 m deep and 1–2 m in diameter, but can be wider and much deeper. Little or no specialised equipment is needed to construct a well – just something to dig with, and a way of removing the spoil. Wells often need to be lined to keep them open, using materials like brick, stones, concrete rings or even lorry tyres. Open wells are vulnerable to contamination from the surface, and can be improved by installing a concrete apron around the top. Wells have large storage, which helps make them less vulnerable to drought, but because they typically tap only shallow groundwater, they can dry up in dry seasons or longer droughts.		*'''Hand-dug wells''' have been dug to access groundwater for thousands of years. They can only be dug in soft material, such as unconsolidated sediment like sand and gravel, weathered basement, or limestone. They are only appropriate where the groundwater level (water table) is shallow. They are usually less than 20 m deep and 1–2 m in diameter, but can be wider and much deeper. Little or no specialised equipment is needed to construct a well – just something to dig with, and a way of removing the spoil. Wells often need to be lined to keep them open, using materials like brick, stones, concrete rings or even lorry tyres. Open wells are vulnerable to contamination from the surface, and can be improved by installing a concrete apron around the top. Wells have large storage, which helps make them less vulnerable to drought, but because they typically tap only shallow groundwater, they can dry up in dry seasons or longer droughts.

	* '''Boreholes''' are narrow diameter tubes drilled into the ground, usually vertically. Boreholes are also called tube wells or simply wells. They can be drilled more quickly and go deeper than hand-dug wells, and so can tap deeper, often more sustainable groundwater; they can be drilled though hard rocks and they can be more easily protected from contamination. There are many different techniques for drilling boreholes, some of which are more suited to certain hydrogeological environments. Usually, a motorised drilling rig is used, operated by specialist drillers. There are also manual drilling techniques.		*'''Boreholes''' are narrow diameter tubes drilled into the ground, usually vertically. Boreholes are also called tube wells or simply wells. They can be drilled more quickly and go deeper than hand-dug wells, and so can tap deeper, often more sustainable groundwater; they can be drilled though hard rocks and they can be more easily protected from contamination. There are many different techniques for drilling boreholes, some of which are more suited to certain hydrogeological environments. Usually, a motorised drilling rig is used, operated by specialist drillers. There are also manual drilling techniques.

	Other, less common ways of accessing groundwater are by:		Other, less common ways of accessing groundwater are by:
	* '''Collector wells''', which are vertical boreholes or wells modified by drilling horizontally out radially below the water table to increase the collection area for groundwater into the central well, from where water is abstracted. They are often constructed in alluvium, next to ephemerally dry ('sand') rivers, with the horizontal radials drilled into the river bed deposits; or in weathered basement.
	* '''Infiltration gallery''', which is a horizontal trench or drain dug below the water table to abstract shallow groundwater, usually from unconsolidated alluvium, including sand rivers, or windblown deposits. The trench drains into a sump from where water is abstracted. The gallery may have to be lined to keep it open.
	* '''Qanats''', which are an ancient method of tapping and transporting groundwater in many parts of North African and the Middle East. A qanat comprises a mother well, often in alluvial deposits at the edge of a mountain range, and a gently inclined covered, underground channel which allows groundwater to flow downhill to a village.

	~~===Testing~~ the ~~yield of a~~ groundwater ~~source===~~		*'''Collector wells''', which are vertical boreholes or wells modified by drilling horizontally out radially below the water table to increase the collection area for groundwater into the central well, from where water is abstracted. They are often constructed in alluvium, next to ephemerally dry ('sand') rivers, with the horizontal radials drilled into the river bed deposits; or in weathered basement.

	~~There are different ways of testing the yield of~~ a ~~borehole~~ or ~~well~~ to ~~assess how much it can sustainably provide~~, ~~but they all involve measuring the maximum pumping rate that can be sustained for a reasonable drawdown of the water level (i.e.~~, ~~so that the water level stays above the pump intake)~~. The ~~following is~~ a ~~brief summary, and more detail~~ is ~~available in [http://nora~~.~~nerc.ac.uk/501046/ MacDonald et al. (2001)] and [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA500019 MacDonald et al. (2005)]~~.		*'''Infiltration gallery''', which is a horizontal trench or drain dug below the water table to abstract shallow groundwater, usually from unconsolidated alluvium, including sand rivers, or windblown deposits. The trench drains into a sump from where water is abstracted. The gallery may have to be lined to keep it open.

	~~An initial estimate of borehole yield can be made when the borehole is airlifted after drilling~~, ~~but this is a very approximate~~ method~~. It gives no information about water level drawdown~~ in ~~the borehole,~~ and ~~therefore no information about~~ the ~~sustainable yield~~. ~~However~~, ~~it can indicate whether~~ a ~~borehole is likely to be productive enough to be worthwhile installing screen~~ and ~~casing~~, ~~and what size of pump~~ to ~~use for~~ a ~~pumping test~~.		*'''Qanats''', which are an ancient method of tapping and transporting groundwater in many parts of North African and the Middle East. A qanat comprises a mother well, often in alluvial deposits at the edge of a mountain range, and a gently inclined covered, underground channel which allows groundwater to flow downhill to a village.

	A short, simple pumping test that is suitable for a relatively low yielding borehole capable of supplying enough water for a hand pump for 250 people, is a bailer test. Water is removed from the borehole with a bailer of known volume for a short time – e.g. 10 minutes – and the water level is measured as it recovers, usually for about 30 to 60 minutes. The equipment needed is a 20 m rope; a stopwatch; a water level dipper; and one or preferably two simple bailers that will fit freely down the borehole. The results can be analysed using sound theoretical principles. The procedure for carrying out and analysing a bailer test is given in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)].		==Groundwater Abstraction Methods==

	~~For higher yielding~~ boreholes, ~~a constant rate test using an~~ electrical pump ~~should be carried out~~. ~~This involves pumping~~ the ~~borehole at a constant rate for a certain period – usually at least 3 hours –~~ and ~~measuring the change~~ in ~~water level in the borehole during pumping and after pumping stops, as~~ the ~~water level recovers. The test results are analysed~~ to ~~give~~ information ~~about aquifer transmissivity – a measure of how easily groundwater can flow through~~ the ~~aquifer. A constant rate test requires a water level dipper and stopwatch, and an electrical pump~~ of ~~suitable size to match the potential borehole yield. A procedure for carrying out and analysing a constant rate test is given in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)]~~.		Groundwater can be abstracted from boreholes and hand-dug wells by traditional methods (buckets, etc); by hand pumps; or by mechanical (e.g. diesel) or electrical submersible pump. Many resources are available to support the choice of which abstraction method to use, and some of these are shown in the section ''Links to more information'' at the bottom of this page.

	~~===Abstracting~~ groundwater===		Most rural water supply boreholes and wells in Africa are installed with hand pumps. There are many different types of hand pump, and the choice of which to use will depend on national standards, ease of maintenance and local expertise, availability of spare parts, the depth of water lift required, the groundwater chemistry (mild steel can corrode), and cost. RWSN provides many resources on [http://www.rural-water-supply.net/en/search?searchword=handpump&searchphrase=all hand pumps], including technical manuals and a number of discussion documents on practice and policy.

	~~Groundwater can be abstracted from boreholes and hand-dug wells by traditional methods (buckets, etc), by hand pumps, or by mechanical (e.g. diesel) or electrical submersible pump.~~ Mechanical or electrical pumps ~~are~~ most appropriate for higher yielding wells or boreholes. Most rural water supply boreholes and wells in Africa are installed with hand pumps. There are many different types of hand pump, and the choice of which to use will depend on national standards, ease of maintenance and local expertise, availability of spare parts, the depth of water lift required, the groundwater chemistry (mild steel can corrode), and cost. RWSN provides many resources on [http://www.rural-water-supply.net/en/search?searchword=handpump&searchphrase=all hand pumps], including technical manuals and a number of discussion documents on practice and policy.		Mechanical or electrical pumps may be most appropriate for higher yielding wells or boreholes.

	~~===Assessing groundwater quality===~~

	The quality of groundwater is almost as important as the yield of a source. In most cases, groundwater from a properly constructed borehole is of good quality and suitable for drinking without any treatment, but some natural elements and pollutants can make groundwater smell or taste unacceptable, or even make it harmful to health. Testing the chemical and bacteriological quality of groundwater is therefore always a good idea. The World Health Organisation sets [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ guidelines for drinking water quality]. A brief introduction to groundwater quality issues and measurement can be found in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)]. Some more background on groundwater quality, particularly related to Africa, is in the [[Groundwater quality in Africa \| Groundwater quality]] resource page.

	==Links to more information==		==Links to more information==

Beod at 16:48, 8 January 2019

2019-01-08T16:48:27Z

← Older revision		Revision as of 17:48, 8 January 2019
Line 40:		Line 40:
	!colspan="4"\|Borehole Testing		!colspan="4"\|Borehole Testing
	\|-		\|-
	\|[[Assessing ~~Borehole~~ Yield \|'''Assessing source yield''']]: in most cases, this means assessing the sustainable yield of a borehole or well by carrying out a pumping test. For springs, it may mean measuring spring flow in different seasons. It is important to measure how much the source will yield sustainably in order to know how many people it can serve.		\|[[Assessing Groundwater Source Yield \|'''Assessing source yield''']]: in most cases, this means assessing the sustainable yield of a borehole or well by carrying out a pumping test. For springs, it may mean measuring spring flow in different seasons. It is important to measure how much the source will yield sustainably in order to know how many people it can serve.
	\|\|A well-trained hydrogeologist or engineer is needed to carry out a pumping test, and normally they need at least 1 day per borehole. For higher yielding boreholes, an electric pump and generator are likely to be needed.		\|\|A well-trained hydrogeologist or engineer is needed to carry out a pumping test, and normally they need at least 1 day per borehole. For higher yielding boreholes, an electric pump and generator are likely to be needed.
	\|-		\|-

Beod at 16:46, 8 January 2019

2019-01-08T16:46:53Z

← Older revision		Revision as of 17:46, 8 January 2019
Line 43:		Line 43:
	\|\|A well-trained hydrogeologist or engineer is needed to carry out a pumping test, and normally they need at least 1 day per borehole. For higher yielding boreholes, an electric pump and generator are likely to be needed.		\|\|A well-trained hydrogeologist or engineer is needed to carry out a pumping test, and normally they need at least 1 day per borehole. For higher yielding boreholes, an electric pump and generator are likely to be needed.
	\|-		\|-
	\|[[Assessing Water Quality'''Assessing water quality''']]: measuring the most important chemical and biological parameters that can impact human health.		\|[[Assessing Water Quality \| '''Assessing water quality''']]: measuring the most important chemical and biological parameters that can impact human health.
	\|\|Some parameters can be measured quickly in the field using relatively simple equipment, but most need to be collected and sent to a laboratory. A well-trained field technician may be needed to carry out sampling.		\|\|Some parameters can be measured quickly in the field using relatively simple equipment, but most need to be collected and sent to a laboratory. A well-trained field technician may be needed to carry out sampling.
	\|}		\|}