Recharge - Revision history

LaurenGiles: /* Artificial Recharge */ UNEP Source book link

2023-12-20T11:28:51Z

Artificial Recharge: UNEP Source book link

← Older revision		Revision as of 12:28, 20 December 2023
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	:- [https://www.artificialrecharge.co.za/ '''South Africa's Artificial Recharge Information Centre''']. This site contains information particularly relevant to South African conditions on Artificial Recharge (AR), Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR).		:- [https://www.artificialrecharge.co.za/ '''South Africa's Artificial Recharge Information Centre''']. This site contains information particularly relevant to South African conditions on Artificial Recharge (AR), Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR).

	:- [https://~~www~~.~~unep~~.~~or.jp~~/~~ietc~~/~~publications/techpublications/techpub-8e/artificial.asp~~ '''UNEP''' - Sourcebook of Alternative Technologies for Freshwater Augmentation in Some Countries in Asia (Chapter 3.10: Artificial Recharge of Groundwater)].		:- [https://digitallibrary.un.org/record/427434 '''UNEP''' - Sourcebook of Alternative Technologies for Freshwater Augmentation in Some Countries in Asia (Chapter 3.10: Artificial Recharge of Groundwater)].

	==A review of recharge estimation techniques used in Africa==		==A review of recharge estimation techniques used in Africa==

LaurenGiles: /* Artificial Recharge */ map of potential artificial recharge areas link

2023-12-20T11:24:37Z

Artificial Recharge: map of potential artificial recharge areas link

← Older revision		Revision as of 12:24, 20 December 2023
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	Some resources with more information are:		Some resources with more information are:

	:- [https://www.un-igrac.org/areas-expertise/managed-aquifer-recharge-mar '''IGRAC - Managed Aquifer Recharge''']. Includes a number of specific studies in Africa, including an online viewer of [https://ggis.un-igrac.org/~~layers~~/~~mar_global:mar_global:marpotential_south_africa~~ '''map of potential artificial recharge areas in South Africa'''], produced by the South African Department of Water Affairs (2009)		:- [https://www.un-igrac.org/areas-expertise/managed-aquifer-recharge-mar '''IGRAC - Managed Aquifer Recharge''']. Includes a number of specific studies in Africa, including an online viewer of [https://ggis.un-igrac.org/catalogue/#/dataset/511 '''map of potential artificial recharge areas in South Africa'''], produced by the South African Department of Water Affairs (2009)

	:- [https://recharge.iah.org''' IAH - Managed Aquifer Recharge''']		:- [https://recharge.iah.org''' IAH - Managed Aquifer Recharge''']

LaurenGiles: /* Chloride mass-balance methods for groundwater from the saturated zone */ fixed punctuation typo

2023-11-29T09:08:16Z

Chloride mass-balance methods for groundwater from the saturated zone: fixed punctuation typo

← Older revision		Revision as of 10:08, 29 November 2023
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	In areas where the hydrogeology is heterogeneous with both focused and diffuse recharge components the estimation of recharge using CMB techniques is more complex, and both physical and chemical (tracer) data are required. However if a mass-balance approach is adopted the shallow groundwater chemistry (an integrated record of first arrival of groundwater by mixed pathways) can still provide information on recharge. This is based on the same assumptions (above) as for diffuse recharge. A good conceptual model of the hydrogeology is essential and conjunctive use of physical and chemical approaches is desirable.		In areas where the hydrogeology is heterogeneous with both focused and diffuse recharge components the estimation of recharge using CMB techniques is more complex, and both physical and chemical (tracer) data are required. However if a mass-balance approach is adopted the shallow groundwater chemistry (an integrated record of first arrival of groundwater by mixed pathways) can still provide information on recharge. This is based on the same assumptions (above) as for diffuse recharge. A good conceptual model of the hydrogeology is essential and conjunctive use of physical and chemical approaches is desirable.

	A recent example of application of the chloride mass balance to an area of basement in Zimbabwe, the Romwe catchment, is given by MacDonald and Edmunds (2013) where it could be validated with estimates of recharge made using physical methods. Groundwater chemistry (mainly major ion ratios) was used to investigate the relative recharge rates in light and dark bands in the gneiss and to test whether soil type was a good indicator of the underlying geology. The CMB method tested in a control catchment was then used to upscale recharge assessment in a larger area. Over and above the limitations made for the unsaturated zone, the effective rainfall must be measured requiring flow data for the catchment. Some limited agricultural return also needed to be taken into account. Groundwater recharge of 21 mm was derived for the mafic aquifer comparing well with the estimates of 24 mm, made separately, using moisture balance and water table fluctuation methods, respectively. The recharge of 4.4 mm calculated for the felsic aquifer does not compare as well with the corresponding 14 mm using the water table fluctuation method. , However, it supports recharge being higher in the more highly weathered mafic igneous rocks of the basement aquifer and this has a wider significance for resources estimation.		A recent example of application of the chloride mass balance to an area of basement in Zimbabwe, the Romwe catchment, is given by MacDonald and Edmunds (2013) where it could be validated with estimates of recharge made using physical methods. Groundwater chemistry (mainly major ion ratios) was used to investigate the relative recharge rates in light and dark bands in the gneiss and to test whether soil type was a good indicator of the underlying geology. The CMB method tested in a control catchment was then used to upscale recharge assessment in a larger area. Over and above the limitations made for the unsaturated zone, the effective rainfall must be measured requiring flow data for the catchment. Some limited agricultural return also needed to be taken into account. Groundwater recharge of 21 mm was derived for the mafic aquifer comparing well with the estimates of 24 mm, made separately, using moisture balance and water table fluctuation methods, respectively. The recharge of 4.4 mm calculated for the felsic aquifer does not compare as well with the corresponding 14 mm using the water table fluctuation method. However, it supports recharge being higher in the more highly weathered mafic igneous rocks of the basement aquifer and this has a wider significance for resources estimation.

	===Physical techniques===		===Physical techniques===

Dbk: Removed protection from "Recharge"

2023-11-28T14:34:26Z

Removed protection from "Recharge"

← Older revision	Revision as of 15:34, 28 November 2023
(No difference)

Beod: /* Artificial Recharge */

2023-01-31T16:07:21Z

Artificial Recharge

← Older revision		Revision as of 17:07, 31 January 2023
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	:- [https://www.artificialrecharge.co.za/ '''South Africa's Artificial Recharge Information Centre''']. This site contains information particularly relevant to South African conditions on Artificial Recharge (AR), Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR).		:- [https://www.artificialrecharge.co.za/ '''South Africa's Artificial Recharge Information Centre''']. This site contains information particularly relevant to South African conditions on Artificial Recharge (AR), Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR).

	:-

	:- [https://www.unep.or.jp/ietc/publications/techpublications/techpub-8e/artificial.asp '''UNEP''' - Sourcebook of Alternative Technologies for Freshwater Augmentation in Some Countries in Asia (Chapter 3.10: Artificial Recharge of Groundwater)].		:- [https://www.unep.or.jp/ietc/publications/techpublications/techpub-8e/artificial.asp '''UNEP''' - Sourcebook of Alternative Technologies for Freshwater Augmentation in Some Countries in Asia (Chapter 3.10: Artificial Recharge of Groundwater)].

Beod: /* Artificial Recharge */

2023-01-31T16:07:12Z

Artificial Recharge

← Older revision		Revision as of 17:07, 31 January 2023
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	==Artificial Recharge==		==Artificial Recharge==

	Artificial recharge is the planned~~, human~~ activity of increasing natural recharge (or infiltration of surface waters into aquifers) with the aim of increasing the amount of groundwater available. Other names for this or related activities are Managed Aquifer Recharge and Aquifer Storage and Recovery. The use of sand dams to artificially increase the potential storage volume for groundwater is one related activity.		[https://www.usgs.gov/mission-areas/water-resources/science/artificial-groundwater-recharge ''Artificial recharge''] is the human, planned activity of increasing natural recharge (or infiltration of surface waters into aquifers) with the aim of increasing the amount of groundwater available. Other names for this or related activities are ''Managed Aquifer Recharge'' and ''Aquifer Storage and Recovery''. The use of sand dams to artificially increase the potential storage volume for groundwater is one related activity.

	Some methods of artificial recharge are simple and have been used for many hundreds or even thousands of years. More technical engineered methods have been used for decades around the world. Artificial recharge or Managed Aquifer Recharge (MAR) technology is flexible and can be applied to many different scales and purposes. However, it can't be used everywhere - aquifer conditions must be suitable, and there must be excess surface water available to recharge.		Some methods of artificial recharge are simple and have been used for many hundreds or even thousands of years. More technical engineered methods have been used for decades around the world. Artificial recharge or Managed Aquifer Recharge (MAR) technology is flexible and can be applied to many different scales and purposes. However, it can't be used everywhere - aquifer conditions must be suitable, and there must be excess surface water available to recharge.
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	Some resources with more information are:		Some resources with more information are:

	:- [https://www.un-igrac.org/areas-expertise/managed-aquifer-recharge-mar '''IGRAC - Managed Aquifer Recharge''']		:- [https://www.un-igrac.org/areas-expertise/managed-aquifer-recharge-mar '''IGRAC - Managed Aquifer Recharge''']. Includes a number of specific studies in Africa, including an online viewer of [https://ggis.un-igrac.org/layers/mar_global:mar_global:marpotential_south_africa '''map of potential artificial recharge areas in South Africa'''], produced by the South African Department of Water Affairs (2009)

	:- [https://recharge.iah.org''' IAH - Managed Aquifer Recharge''']		:- [https://recharge.iah.org''' IAH - Managed Aquifer Recharge''']

	:- [https://www.~~unep~~.or.jp/~~ietc/publications/techpublications/techpub-8e/artificial.asp~~ '''~~UNEP~~''' ~~- Sourcebook of Alternative Technologies for Freshwater Augumentation in Some Countries in Asia (Chapter 3~~.~~10:~~ Artificial Recharge ~~of Groundwater~~)].		:- [https://www.artificialrecharge.co.za/ '''South Africa's Artificial Recharge Information Centre''']. This site contains information particularly relevant to South African conditions on Artificial Recharge (AR), Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR).

			:-

			:- [https://www.unep.or.jp/ietc/publications/techpublications/techpub-8e/artificial.asp '''UNEP''' - Sourcebook of Alternative Technologies for Freshwater Augmentation in Some Countries in Asia (Chapter 3.10: Artificial Recharge of Groundwater)].

	==A review of recharge estimation techniques used in Africa==		==A review of recharge estimation techniques used in Africa==

Beod at 15:50, 31 January 2023

2023-01-31T15:50:27Z

← Older revision		Revision as of 16:50, 31 January 2023
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	[https://en.wikipedia.org/wiki/Groundwater_recharge '''Groundwater recharge'''] - which hydrogeologists just call recharge - is a hydrological process which results in the replenishment, or renewal, of groundwater in aquifers. Recharge is the main control on the volume of renewable groundwater resource.		[https://en.wikipedia.org/wiki/Groundwater_recharge '''Groundwater recharge'''] - which hydrogeologists just call recharge - is a hydrological process which results in the replenishment, or renewal, of groundwater in aquifers. Recharge is the main control on the volume of renewable groundwater resource.

	Recharge processes are very variable, and controlled by many factors including climatic zone, weather patterns, geology and land use. Recharge can be natural (through the water cycle) and/or through anthropogenic processes (~~i.e., "~~artificial ~~groundwater~~ recharge"), where rainwater, surface water and/or reclaimed water is deliberately routed to aquifers. It can be direct - where rainfall infiltrates directly into aquifers through soil, sediments or rock; or it can be indirect - e.g. ~~surface water~~ flows first over ~~impermeable~~ land and into rivers or lakes before ~~later~~ infiltrating down into aquifers in a different place from where it fell ~~as rain~~. It can be diffuse, ~~e.g.~~ water (rainwater or artificially applied water) infiltrates through the soil and any superficial deposits or bedrock to the water table, ~~which can be distributed~~ over large areas; or it can be focussed ~~recharge~~, ~~e.g.~~ where water infiltrates ~~from~~ point sources or small areas, such as wadis or lakes, or land surface depressions.		Recharge processes are very variable, and controlled by many factors including climatic zone, weather patterns, geology and land use. Recharge can be natural (through the water cycle) and/or through anthropogenic processes (artificial recharge), where rainwater, surface water and/or reclaimed water is deliberately routed to aquifers. It can be direct - where rainfall infiltrates directly into aquifers through soil, sediments or rock; or it can be indirect - e.g. rainfall flows first over the land surface and into rivers or lakes before infiltrating down into aquifers in a different place from where it originally fell. Recharge can be diffuse, where water (rainwater or artificially applied water) infiltrates through the soil and any superficial deposits or bedrock to the water table, sometimes over large areas; or it can be focussed, where water infiltrates the ground preferentially at point sources or small areas, such as wadis or lakes, or land surface depressions.

	==Recharge estimations for Africa==		==Recharge estimations for Africa==

	Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable ~~estimates~~ of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.		Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable assessments of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers. There have been many site-specific studies of groundwater recharge at locations across Africa. These vary a lot in what estimation methods were used; in study scale; in the geographical, climatic and geological characteristics of the study region; and in the quality of data available. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by global experts in recharge, WM Edmunds and BR Scanlon, for an [https://upgro.org/catalyst-projects/groundwater-recharge/ '''UPGro project'''] in 2014, and is included in full on this page - [[#A review of recharge estimation techniques used in Africa \| '''a review of recharge estimation techniques used in Africa''']].

	~~There have~~ been ~~many site-specific studies~~ of ~~groundwater recharge at locations across~~ Africa~~. These vary significantly in the study scale; the geographical~~, ~~climatic and geological characteristics~~ of ~~the study region; the quality of data available; and the estimation methods used. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by~~ global ~~experts in recharge~~, ~~WM Edmunds and BR Scanlon~~, ~~for an~~ [https://~~upgro~~.org/~~catalyst-projects~~/~~groundwater-recharge/~~ '''~~UPGro project~~'''] ~~in 2014,~~ and ~~is included in full on this page~~ - ~~[[#A review of recharge estimation techniques used in Africa \|~~ '''~~a review of recharge estimation techniques used in Africa~~''']].		Until recently, recharge rates had not been mapped across the whole of Africa, except at coarse resolution as part of large scale global models, such as [https://doi.org/10.1029/2022GL099010 '''Berghuijs et al. (2022)'''], [https://doi.org/10.1016/j.scitotenv.2020.137042 '''Moeck et al. (2020)'''] and [https://www.hydrol-earth-syst-sci.net/12/863/2008/hess-12-863-2008.html '''Döll and Fiedler (2008)'''].

	Until recently, recharge rates had not been mapped across the whole of Africa, except from large scale global models, such as [https://doi.org/10.1029/2022GL099010 '''Berghuijs et al. (2022)'''], [https://doi.org/10.1016/j.scitotenv.2020.137042 '''Moeck et al. (2020)'''] and [https://www.hydrol-earth-syst-sci.net/12/863/2008/hess-12-863-2008.html '''Döll and Fiedler (2008)'''].		A recent study by [https://dx.doi.org/10.1088/1748-9326/abd661 '''MacDonald et al. (2021)'''] provided a more detailed recharge estimate for the whole of Africa. This has also been used to ground-truth recharge estimates for Africa from eight global scale models, by [https://doi.org/10.1016/j.scitotenv.2022.159765 '''West et al. (2023)'''].

	~~However, a~~ recent study by [https://dx.doi.org/10.1088/1748-9326/abd661 '''MacDonald et al. (2021)'''] provided a more detailed recharge estimate for the whole of Africa. This has also been used to ground-truth recharge estimates for Africa from eight global scale models, by [https://doi.org/10.1016/j.scitotenv.2022.159765 '''West et al. (2023)'''].

	In their paper, [https://dx.doi.org/10.1088/1748-9326/abd661 '''MacDonald et al. (2021)'''] quantify long-term average distributed groundwater recharge rates across Africa based on 134 ground-based estimates. This was the first ground-based approximation of recharge across the whole of Africa. They estimate that average recharge every decade in Africa is 15 000 km<sup>3</sup> (4900–45 000 km<sup>3</sup>), or approximately 2% of estimated groundwater storage across the continent. However, recharge across Africa is characterised by great variability between different aquifer types (hydrogeological environments): in particular, between sedimentary aquifers in North Africa (high storage and low recharge) and weathered crystalline/basement rock aquifers (low storage and high recharge) across much of tropical Africa.		In their paper, [https://dx.doi.org/10.1088/1748-9326/abd661 '''MacDonald et al. (2021)'''] quantify long-term average distributed groundwater recharge rates across Africa based on 134 ground-based estimates. This was the first ground-based approximation of recharge across the whole of Africa. They estimate that average recharge every decade in Africa is 15 000 km<sup>3</sup> (4900–45 000 km<sup>3</sup>), or approximately 2% of estimated groundwater storage across the continent. However, recharge across Africa is characterised by great variability between different aquifer types (hydrogeological environments): in particular, between sedimentary aquifers in North Africa (high storage and low recharge) and weathered crystalline/basement rock aquifers (low storage and high recharge) across much of tropical Africa.
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	[https://doi.org/10.1016/j.scitotenv.2022.159765 '''West et al. (2023)'''] compare recharge and recharge ratio (annual recharge/annual precipitation) estimates from eight global models with the same dataset of over 100 ground-based estimates in Africa. They showed that global modelled recharge estimates disagree significantly across the different landscapes of Africa, and also vary considerably and inconsistently in how closely they match ground-based estimates. The global-scale models that allowed stronger climatic controls on their recharge estimates were more similar to ground-based estimates in Africa. The authors stress that this means groundwater recharge prediction across Africa should not rely on estimates from a single model but instead look at the distribution of estimates from different models.		[https://doi.org/10.1016/j.scitotenv.2022.159765 '''West et al. (2023)'''] compare recharge and recharge ratio (annual recharge/annual precipitation) estimates from eight global models with the same dataset of over 100 ground-based estimates in Africa. They showed that global modelled recharge estimates disagree significantly across the different landscapes of Africa, and also vary considerably and inconsistently in how closely they match ground-based estimates. The global-scale models that allowed stronger climatic controls on their recharge estimates were more similar to ground-based estimates in Africa. The authors stress that this means groundwater recharge prediction across Africa should not rely on estimates from a single model but instead look at the distribution of estimates from different models.

			==Controls on recharge in Africa===

			[https://doi.org/10.1016/j.jhydrol.2022.127967 '''West et al. (2022)'''] carried out a review of previous recharge studies across Africa to identify the dominant controls on recharge processes and volumes. They identified a number of climatic, topographic, vegetation, soil and geologic properties that appear to have consistent impacts on recharge, and developed a series of indices based on selected these properties to characterise different controls on recharge. They used these indices to divide Africa into 15 ''Recharge Landscape Units'' within which they suggest that recharge controls are likely to be similar. Over 80% of Africa's land area is accounted for by just nine of these units.

	==Artificial Recharge==		==Artificial Recharge==

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	Scanlon BR, Healy RW and Cook PG. 2002. [https://link.springer.com/content/pdf/10.1007%2Fs10040-001-0176-2.pdf Choosing appropriate techniques for quantifying groundwater recharge]. Hydrogeology Journal 10, 18–39		Scanlon BR, Healy RW and Cook PG. 2002. [https://link.springer.com/content/pdf/10.1007%2Fs10040-001-0176-2.pdf Choosing appropriate techniques for quantifying groundwater recharge]. Hydrogeology Journal 10, 18–39

			West C, Rosolem R, MacDonald AM, Cuthbert MO and Wagener T. 2022. [https://doi.org/10.1016/j.jhydrol.2022.127967 Understanding process controls on groundwater recharge variability across Africa through recharge landscapes]. Journal of Hydrology 612, Part A.

	West C, Reinecke R, Rosolem R, MacDonald AM, Cuthbert MO and Wagener T. 2023. [https://doi.org/10.1016/j.scitotenv.2022.159765 Ground truthing global-scale model estimates of groundwater recharge across Africa]. Science of The Total Environment 858 (3). Doi: 10.1016/j.scitotenv.2022.159765 .		West C, Reinecke R, Rosolem R, MacDonald AM, Cuthbert MO and Wagener T. 2023. [https://doi.org/10.1016/j.scitotenv.2022.159765 Ground truthing global-scale model estimates of groundwater recharge across Africa]. Science of The Total Environment 858 (3). Doi: 10.1016/j.scitotenv.2022.159765 .

Beod: /* Recharge estimations for Africa */

2023-01-31T15:13:46Z

Recharge estimations for Africa

← Older revision		Revision as of 16:13, 31 January 2023
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	==Recharge estimations for Africa==		==Recharge estimations for Africa==

	Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are: chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.		Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.

	There have been many site-specific studies of groundwater recharge at locations across Africa. These vary significantly in the study scale; the geographical, climatic and geological characteristics of the study region; the quality of data available; and the estimation methods used. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by global experts in recharge, WM Edmunds and BR Scanlon, for an [https://upgro.org/catalyst-projects/groundwater-recharge/ '''UPGro project'''] in 2014, and is included in full on this page - [[#A review of recharge estimation techniques used in Africa \| '''a review of recharge estimation techniques used in Africa''']].		There have been many site-specific studies of groundwater recharge at locations across Africa. These vary significantly in the study scale; the geographical, climatic and geological characteristics of the study region; the quality of data available; and the estimation methods used. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by global experts in recharge, WM Edmunds and BR Scanlon, for an [https://upgro.org/catalyst-projects/groundwater-recharge/ '''UPGro project'''] in 2014, and is included in full on this page - [[#A review of recharge estimation techniques used in Africa \| '''a review of recharge estimation techniques used in Africa''']].

Beod at 15:13, 31 January 2023

2023-01-31T15:13:13Z

← Older revision		Revision as of 16:13, 31 January 2023
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	Recharge processes are very variable, and controlled by many factors including climatic zone, weather patterns, geology and land use. Recharge can be natural (through the water cycle) and/or through anthropogenic processes (i.e., "artificial groundwater recharge"), where rainwater, surface water and/or reclaimed water is deliberately routed to aquifers. It can be direct - where rainfall infiltrates directly into aquifers through soil, sediments or rock; or it can be indirect - e.g. surface water flows first over impermeable land and into rivers or lakes before later infiltrating down into aquifers in a different place from where it fell as rain. It can be diffuse, e.g. water (rainwater or artificially applied water) infiltrates through the soil and any superficial deposits or bedrock to the water table, which can be distributed over large areas; or it can be focussed recharge, e.g. where water infiltrates from point sources or small areas, such as wadis or lakes, or land surface depressions.		Recharge processes are very variable, and controlled by many factors including climatic zone, weather patterns, geology and land use. Recharge can be natural (through the water cycle) and/or through anthropogenic processes (i.e., "artificial groundwater recharge"), where rainwater, surface water and/or reclaimed water is deliberately routed to aquifers. It can be direct - where rainfall infiltrates directly into aquifers through soil, sediments or rock; or it can be indirect - e.g. surface water flows first over impermeable land and into rivers or lakes before later infiltrating down into aquifers in a different place from where it fell as rain. It can be diffuse, e.g. water (rainwater or artificially applied water) infiltrates through the soil and any superficial deposits or bedrock to the water table, which can be distributed over large areas; or it can be focussed recharge, e.g. where water infiltrates from point sources or small areas, such as wadis or lakes, or land surface depressions.

	==~~Estimating recharge~~ for Africa==		==Recharge estimations for Africa==

	Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are: chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.		Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are: chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.

Beod: /* Estimating recharge for Africa */

2023-01-31T12:01:11Z

Estimating recharge for Africa

← Older revision		Revision as of 13:01, 31 January 2023
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	==Estimating recharge for Africa==		==Estimating recharge for Africa==

	Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing.		Groundwater recharge is one of the most difficult parameters to measure when assessing groundwater resources, but in order to make reliable estimates of sustainable groundwater resources, it is vital to know how much recharge is occurring to aquifers, and extremely useful to understand recharge processes and timing. The most common methods to estimate recharge rates are: chloride mass balance; soil physics methods; environmental and isotopic tracers; groundwater level fluctuation methods; water balance methods (including numerical groundwater modelling) and the estimation of baseflow to rivers.

	There have been many site-specific studies of groundwater recharge at locations across Africa. These vary significantly in the study scale; the geographical, climatic and geological characteristics of the study region; the quality of data available; and the estimation methods used. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by global experts in recharge, WM Edmunds and BR Scanlon, for an [https://upgro.org/catalyst-projects/groundwater-recharge/ '''UPGro project'''] in 2014, and is included in full on this page - [[#A review of recharge estimation techniques used in Africa \| '''a review of recharge estimation techniques used in Africa''']].		There have been many site-specific studies of groundwater recharge at locations across Africa. These vary significantly in the study scale; the geographical, climatic and geological characteristics of the study region; the quality of data available; and the estimation methods used. A detailed review of recharge estimation techniques used in more than 200 studies across Africa was written by global experts in recharge, WM Edmunds and BR Scanlon, for an [https://upgro.org/catalyst-projects/groundwater-recharge/ '''UPGro project'''] in 2014, and is included in full on this page - [[#A review of recharge estimation techniques used in Africa \| '''a review of recharge estimation techniques used in Africa''']].