MediaWiki - User contributions [en]

Overview of Groundwater in Africa

2015-07-29T14:35:29Z

Sdw:

Groundwater is an invaluable resource in Africa, providing a safe and reliable source of drinking water for many people and supporting food production through irrigation. Groundwater is generally more resilient to short-term climate variability and less vulnerable to pollution than surface water sources. However, sustainable groundwater development requires careful characterization of the resource to avoid long-term depletion and environmental degradation. This will become increasingly important as more pressure is applied to Africa's groundwater resources under population growth and higher irrigation demand.

The occurrence of groundwater depends on a number of interacting factors, including geology, geomorphology and weathering, and rainfall and evaporation. Spatial and temporal variations in these factors can produce highly complex hydrogeological environments with significant variations in aquifer properties, aquifer saturated thickness, and recharge. Quantification of these factors, and an understanding of the interplay between them, is required to properly characterize a groundwater resource.

However, for many parts of Africa very little groundwater information is readily available (Figure). This may be due to a lack of data collection, or simply due to issues of data accessibility. In areas where data is not available or easily accessible, it becomes very difficult to quantify the available resource. This often leads to inappropriate exploitation of an aquifer causing longer term issues of groundwater availability and quality.

Many studies have recently or are currently being undertaken to address some of the key knowledge gaps of groundwater resources in Africa. This section of the Atlas brings together available information to provide a continental-scale overview of:

# [[Hydrogeological environments of Africa | The main hydrogeological environments of Africa]]
# [[Groundwater quality in Africa | Major groundwater quality issues in Africa]]
# [[Groundwater use and management in Africa | Groundwater use and management in Africa]]

The sections above provide general background and context to the more detailed information available under each [[Hydrogeology by country | country profile]].

[[Category:Overview of Groundwater in Africa | 004]]

Overview of Groundwater in Africa

2015-07-29T14:35:05Z

Sdw:

Groundwater is an invaluable resource in Africa, providing a safe and reliable source of drinking water for many people and supporting food production through irrigation. Groundwater is generally more resilient to short-term climate variability and less vulnerable to pollution than surface water sources. However, sustainable groundwater development requires careful characterization of the resource to avoid long-term depletion and environmental degradation. This will become increasingly important as more pressure is applied to Africa's groundwater resources under population growth and higher irrigation demand.

The occurrence of groundwater depends on a number of interacting factors, including geology, geomorphology and weathering, and rainfall and evaporation. Spatial and temporal variations in these factors can produce highly complex hydrogeological environments with significant variations in aquifer properties, aquifer saturated thickness, and recharge. Quantification of these factors, and an understanding of the interplay between them, is required to properly characterize a groundwater resource.

However, for many parts of Africa very little groundwater information is readily available (Figure). This may be due to a lack of data collection, or simply due to issues of data accessibility. In areas where data is not available or easily accessible, it becomes very difficult to quantify the available resource. This often leads to inappropriate exploitation of an aquifer causing longer term issues of groundwater availability and quality.

Many studies have recently or are currently being undertaken to address some of the key knowledge gaps of groundwater resources in Africa. This section of the Atlas brings together available information to provide a continental-scale overview of:q

# [[Hydrogeological environments of Africa | The main hydrogeological environments of Africa]]
# [[Groundwater quality in Africa | Major groundwater quality issues in Africa]]
# [[Groundwater use and management in Africa | Groundwater use and management in Africa]]

The sections above provide general background and context to the more detailed information available under each [[Hydrogeology by country | country profile]].

[[Category:Overview of Groundwater in Africa | 004]]

Overview of Groundwater in Africa

2015-07-29T14:34:27Z

Sdw:

Overview of Groundwater in Africa

2015-07-29T14:34:05Z

Sdw:

Groundwater is an invaluable resource in Africa, providing a safe and reliable source of drinking water for many people and supporting food production through irrigation. Groundwater is generally more resilient to short-term climate variability and less vulnerable to pollution than surface water sources. However, sustainable groundwater development requires careful characterization of the resource to avoid long-term depletion and environmental degradation. This will become increasingly important as more pressure is applied to Africa's groundwater resources under population growth and higher irrigation demand.

The occurrence of groundwater depends on a number of interacting factors, including geology, geomorphology and weathering, and rainfall and evaporation. Spatial and temporal variations in these factors can produce highly complex hydrogeological environments with significant variations in aquifer properties, aquifer saturated thickness, and recharge. Quantification of these factors, and an understanding of the interplay between them, is required to properly characterize a groundwater resource.

However, for many parts of Africa very little groundwater information is readily available (Figure). This may be due to a lack of data collection, or simply due to issues of data accessibility. In areas where data is not available or easily accessible, it becomes very difficult to quantify the available resource. This often leads to inappropriate exploitation of an aquifer causing longer term issues of groundwater availability and quality.

Many studies have recently or are currently being undertaken to address some of the key knowledge gaps of groundwater resources in Africa. This section of the Atlas brings together available information to provide a continental-scale overview of:q

# [[Hydrogeological environments of Africa | The main hydrogeological environments of Africa]]
# [[Groundwater quality in Africa | Major groundwater quality issues in Africa]]
# [[Groundwater use and management in Africa | Groundwater use and management in Africa]]

The sections above provide general background and context to the more detailed information available under each [[Hydrogeology by country | country profile]].

[[Category:Overview of Groundwater in Africa | 004]]

OR/14/001 About the corroded asset failure - ferrous map

2015-03-24T15:13:37Z

Sdw: /* The Corroded' 'Asset' 'Failure' '- Ferrous map (summary) comprises one GIS layer called ‘Ferrous_failure_summary’ that considers the potential for corroded assets to fail as a result of ground instability. This summary map provides an overview o...

__NOTOC__
=Background=

Underground ferrous assets are structures in the ground that contain iron, such as foundations, cabling and gas, water and oil pipelines. The failure of underground assets is a significant problem for both historical and newly placed underground infrastructure. The term ‘failure’ covers assets which will no longer work according to their original specification; failure of a pipe may mean it leaks, or failure of a foundation may mean that its bearing capacity is compromised. Failure may occur as a result of the following factors (Makar, 2000):

* Corrosion

* External loading (differential ground movement)

* Manufacturing flaws

* Internal pressure

This dataset focuses on the susceptibility of assets to fail as a result of corrosion resulting from aggressive soils and differential ground movement. The effect of soil corrosivity on ferrous assets is dependent on the soil type and specifically the concentration of soluble salts such as sulphate and chloride, pH, soil resistivity, water content, temperature and soil redox potential. Ferrous assets that are corroded by aggressive soils have a reduced material thickness, which increases the chance of failure. This is particularly the case where differential ground movement occurs, putting greater external pressure on assets (Eidinger, 1998). Ground movement can occur in a variety of scenarios due to the susceptibility of geological deposits to landslide, shrink-swell, compression, collapse, dissolution and to running sands.

The Corroded Asset Failure - Ferrous map considers the potential for ferrous asset failure as a result of aggressive soil conditions causing ferrous corrosion, and the potential for ground movement. It indicates where corroded ferrous assets are most likely to fail due to ground movement.

Water leaking from pipes has the potential to further worsen ground instability hazards causing additional instability to adjacent infrastructure. A map entitled ‘Pipe Leakage Impacts’ has been developed to complement the map described in this user guide. It provides an indication of where pipe leakage may worsen ground movement. Further information about this map is available at in Dearden et al., (2014).

==Who might require this map?==

The ''Corroded Asset Failure - Ferrous ''map is relevant to those asset managers who install, design and maintain ferrous assets. In particular the dataset will help:

* determine where assets are most susceptible to failure as a result of both aggressive soils and ground movement;

* prioritise investigations into where ferrous assets are most likely to fail, and

* assess where the specification of new ferrous assets may need to take into account corrosion and ground movement.

The dataset is relevant to professionals involved in subsurface asset management in water companies, construction and other utility companies. It may also be of interest to solicitors, loss adjusters and the insurance industry. The map is derived from datasets at a scale of 1:50 000.

==About the dataset==

===Overview===

There are two versions of the map; summary and detailed. The contents of these are described in Section

===Detailed datasets===

The ''Corroded Asset Failure'' Ferrous map (detailed) comprises one GIS layer called ‘Ferrous_failure’ that considers the potential for corroded assets to fail as a result of ground instability. It includes a summary map providing an overview of the susceptibility to failure as a result of the combined effect of aggressive soils and ground movement. It also includes a further seven sub-layers that provide more detailed information about the potential for corrosion and the type of ground movement that may occur. [Figure 1] illustrates the type of data provided.

[[Image:14/001_fig1.png|thumb|center|400px|'''Figure 1''' An example of the GIS layer that considers the potential for corroded assets to fail as a result of ground instability]]

name="2.3.3_Summary_datasets" name="_bookmark2"'''2.3.3 ''''''Summary'''''' datasets'''

=== The ''Corroded'''' ''''Asset'''' ''''Failure'''' ''''- Ferrous ''map (summary) comprises one GIS layer called ‘Ferrous_failure_summary’ that considers the potential for corroded assets to fail as a result of ground instability. This summary map provides an overview of the susceptibility to failure as a result of the combined effect of aggressive soils and ground movement, but it does not indicate which hazards are potentially present (Figure 2). ===

[[Image:filename|thumb|widthpx| ]]

[[File:C:\Users\sdw\AppData\Local\Temp\msohtmlclip1\01\clip_image004.jpg|505px]]

'''Figure 2 An example of the summary GIS layer that considers the potential for corroded assets to fail as a result of ground instability'''

[[Category:OR/14/001 User Guide for the Corroded Asset Failure – Ferrous map| 02]]

OR/14/001 About the corroded asset failure - ferrous map

2015-03-24T15:12:01Z

Sdw:

OR/14/001 About the corroded asset failure - ferrous map

2015-03-24T15:01:48Z

Sdw: Created page with "=Background= Underground ferrous assets are structures in the ground that contain iron, such as foundations, cabling and gas, water and oil pipelines. The failure of undergro..."

=Background=

Underground ferrous assets are structures in the ground that contain iron, such as foundations, cabling and gas, water and oil pipelines. The failure of underground assets is a significant problem for both historical and newly placed underground infrastructure. The term ‘failure’ covers assets which will no longer work according to their original specification; failure of a pipe may mean it leaks, or failure of a foundation may mean that its bearing capacity is compromised. Failure may occur as a result of the following factors (Makar, 2000):

* Corrosion

* External loading (differential ground movement)

* Manufacturing flaws

* Internal pressure

This dataset focuses on the susceptibility of assets to fail as a result of corrosion resulting from aggressive soils and differential ground movement. The effect of soil corrosivity on ferrous assets is dependent on the soil type and specifically the concentration of soluble salts such as sulphate and chloride, pH, soil resistivity, water content, temperature and soil redox potential. Ferrous assets that are corroded by aggressive soils have a reduced material thickness, which increases the chance of failure. This is particularly the case where differential ground movement occurs, putting greater external pressure on assets (Eidinger, 1998). Ground movement can occur in a variety of scenarios due to the susceptibility of geological deposits to landslide, shrink-swell, compression, collapse, dissolution and to running sands.

The Corroded Asset Failure - Ferrous map considers the potential for ferrous asset failure as a result of aggressive soil conditions causing ferrous corrosion, and the potential for ground movement. It indicates where corroded ferrous assets are most likely to fail due to ground movement.

Water leaking from pipes has the potential to further worsen ground instability hazards causing additional instability to adjacent infrastructure. A map entitled ‘Pipe Leakage Impacts’ has been developed to complement the map described in this user guide. It provides an indication of where pipe leakage may worsen ground movement. Further information about this map is available at in Dearden et al., (2014).

==Who might require this map?==

The ''Corroded Asset Failure - Ferrous ''map is relevant to those asset managers who install, design and maintain ferrous assets. In particular the dataset will help:

* determine where assets are most susceptible to failure as a result of both aggressive soils and ground movement;

* prioritise investigations into where ferrous assets are most likely to fail, and

* assess where the specification of new ferrous assets may need to take into account corrosion and ground movement.

The dataset is relevant to professionals involved in subsurface asset management in water companies, construction and other utility companies. It may also be of interest to solicitors, loss adjusters and the insurance industry. The map is derived from datasets at a scale of 1:50 000.

==About the dataset==

===Overview===

There are two versions of the map; summary and detailed. The contents of these are described in Section

===Detailed datasets===

The ''Corroded Asset Failure'' Ferrous ''map (detailed) comprises one GIS layer called ‘Ferrous_failure’ that considers the potential for corroded assets to fail as a result of ground instability. It includes a summary map providing an overview of the susceptibility to failure as a result of the combined effect of aggressive soils and ground movement. It also includes a further seven sub-layers that provide more detailed information about the potential for corrosion and the type of ground movement that may occur. [Figure 1] illustrates the type of data provided.

[[Image:14/001_fig1.png|thumb|center|400px|'''Figure 1''' An example of the GIS layer that considers the potential for corroded assets to fail as a result of ground instability]]

name="2.3.3_Summary_datasets" name="_bookmark2"'''2.3.3 ''''''Summary'''''' datasets'''

=== The ''Corroded'''' ''''Asset'''' ''''Failure'''' ''''- Ferrous ''map (summary) comprises one GIS layer called ‘Ferrous_failure_summary’ that considers the potential for corroded assets to fail as a result of ground instability. This summary map provides an overview of the susceptibility to failure as a result of the combined effect of aggressive soils and ground movement, but it does not indicate which hazards are potentially present (Figure 2). ===

[[File:C:\Users\sdw\AppData\Local\Temp\msohtmlclip1\01\clip_image004.jpg|505px]]

'''Figure 2 An example of the summary GIS layer that considers the potential for corroded assets to fail as a result of ground instability'''

OR/14/001 Introduction

2015-03-24T14:49:26Z

Sdw:

Founded in 1835, the British Geological Survey (BGS) is the world's oldest national geological survey and the United Kingdom's premier centre for earth science information and expertise. The BGS provides expert services and impartial advice in all areas of geosciences and has a client base that is drawn from the public and private sectors both in the UK and internationally. Our innovative digital data products aim to help describe the ground surface and subsurface across the whole of Great Britain. These digital products are based on the outputs of the BGS survey and research programmes and our substantial national data holdings. This data coupled with our in-house geoscientific knowledge are combined to provide products relevant to a wide range of users in central and local government, insurance and housing, engineering and environmental business, and the British public.

'''Further information on all the digital data provided by the BGS can be found on our website at [http://www.bgs.ac.uk/data/home.html http://www.bgs.ac.uk/data/home.html ]or by contacting:'''

Central Enquiries British Geological Survey Environmental Science Centre Keyworth Nottingham NG12 5GG Direct tel. +44(0)115 936 3143 Fax. +44(0)115 9363150

email [mailto:enquiries@bgs.ac.uk '''<u>enquiries@bgs.ac.uk</u>''']

[[Category:OR/14/001 User Guide for the Corroded Asset Failure – Ferrous map| 01]]

OR/14/001 Introduction

2015-03-24T14:48:11Z

Sdw: Created page with "Founded in 1835, the British Geological Survey (BGS) is the world's oldest national geological survey and the United Kingdom's premier centre for earth science information and..."

Category:OR/14/008 The Stratigraphical framework for the Palaeogene successions of the London Basin, UK

2015-03-24T14:45:15Z

Sdw:

{{OR/14/008}}

[[Category:BGS Open Reports| 04 ]]

Category:OR/14/001 User Guide for the Corroded Asset Failure – Ferrous map

2015-03-24T14:44:55Z

Sdw:

[[Category:BGS Open Reports| 01]]

Category:OR/14/001 User Guide for the Corroded Asset Failure – Ferrous map

2015-03-24T14:43:54Z

Sdw: Created page with "Category:BGS Open Reports"

[[Category:BGS Open Reports]]