New state-of-the-art research collection on groundwater sustainability across Sub-Saharan Africa

An important new collection of papers has just been published online in the Hydrogeology Journal:

Substantial increases in groundwater withdrawals are expected across Sub-Saharan Africa to help nations increase access to safe water and to amplify agricultural production in pursuit of UN SDG 2 and SDG 6.  Long-term groundwater-level records or chronicles play an important role in developing an improved understanding of the hydrogeological and climatic conditions that control access and sustain well yields, informing where, when and how groundwater withdrawals can sustainably contribute to building resilience and alleviating poverty.

There are four papers in the collection (and an overview essay) that provide a sample of the new research outputs emanating from The Chronicles Consortium and UPGro GroFutures:

  • Evidence from chronicles in seasonally humid Benin and Uganda show annual cycles of replenishment from direct, diffuse recharge generated preferentially by heavy rainfalls. Kotchoni et al. show how chronicles from different geological environments in Benin can be modelled very effectively on a daily timestep with an improved watertable fluctuation model.
  • In semi-arid southwestern Niger, chronicles show that recharge to weathered crystalline rock aquifer systems occurs directly from rainfall but is restricted by a thick clayey aquitard developed from schist. However, greater recharge is shown to occur indirectly via riverbeds of ephemeral streams which provide preferential pathways through the saprolite.
  • Evidence from the Makutapora Wellfield of semi-arid central Tanzania that groundwater, abstracted at rates exceeding 30,000 m3/day, is sustained by episodic recharge associated with El Niño Southern Oscillation (ENSO). Further, abstracted groundwater is partially modern, derived from rainfall within the last 10–60 years.
  • Studies from Benin and Niger highlight the low storage of weathered crystalline rock aquifers and the importance of modern recharge in sustaining groundwater use. The low storage and low but highly variable hydraulic conductivity of weathered and fractured crystalline rock aquifers found over more than 40% of Sub-Saharan Africa may, however, have a potential advantage. Such aquifer systems restrict opportunities for intensive and competitive abstraction and are thus potentially self-regulating. Low-intensity groundwater abstraction distributed across the landscape also complements existing land-tenure systems in many areas of Sub-Saharan Africa dominated by smallholder agriculturalists.
  • The chronicles provide invaluable datasets to help direct assessments of past impacts of climate variability—e.g. ENSO, Atlantic Multi-decadal Oscillation (AMO)— and abstraction on groundwater storage. Such records, when continuously updated, can also provide key input to water resources management by tracking emerging risks to water security from groundwater storage decline or groundwater flooding (e.g. Murray et al. 2018).
  • Regional-scale (>50,000 km2) networks of long-term piezometric records can also be used to test the reliability of largescale, satellite observations from the Gravity Anomaly and Climate Experiment (GRACE). Indeed, the emergence of GRACE measurements of changes in total terrestrial water storage adds a potential tool, albeit at a much larger scale (>200,000 km2), to estimate changes in groundwater storage where records do not exist. However, there are substantial uncertainties from such estimates.

For full details read:

Please note that all five papers are open until 30 April, after which only 3 of the papers will be Open Access.

Text adapted from Topical Collection: Determining groundwater sustainability from long-term piezometry in Sub-Saharan Africa

3 new UPGro papers + Groundwater to be the UN-Water theme for 2022

We are delighted to report that UN-Water, the coordinating body for water issues across the United Nations, in a meeting this week agreed to make the theme of the 2022 World Water Development Report and World Water Day: “Groundwater: making the invisible visible” http://enb.iisd.org/water/un/30/html/enbplus82num34e.html

Meanwhile three new UPGro papers have recently been published:

“Groundwater hydrodynamics of an Eastern Africa coastal aquifer, including La Niña 2016–17 drought”

Núria Ferrera; Albert Folch; Mike Lane; Daniel Olago; JuliusOdida; Emilio Custodio  (Gro for GooD)

Key Points

  • An East African costal aquifer was characterized before and during La Niña 2016/17.
  • The recharge was reduced 69% compared to average annual rainfall.
  • Lower recharge during first and nil recharge during the second wet season
  • No important groundwater quality changes observed inland
  • Increase of seawater intrusion even during the wet season

This paper is accessible from here: https://www.sciencedirect.com/science/article/pii/S0048969719302177?dgcid=coauthor until 13 March

“A case for urban liveability from below: exploring the politics of water and land access for greater liveability in Kampala, Uganda”

Maryam Nastar, Jennifer Isoke, Robinah Kulabako & Giorgia Silvestri (T-GroUP) https://www.tandfonline.com/doi/full/10.1080/13549839.2019.1572728

Key Points

  • Despite efforts of local governments and NGOs to put public service delivery systems in place, there is a gap between goals and actual impacts on citizens’ quality of life
  • Decentralisation has faced challenges from the emergence of national partisan political struggles in local areas.
  • Pre-paid standpipes were installed with magnetic charge cards handed out for free. Initially a UGX25 card top-up bought 4 jerry cans (20l), overtime this reduced to 3 jerry cans. If a card was lost or stolen then a replacement cost users UGX15,000-25,000, which was unaffordable to many slum dwellers who then bought water from the standpipe caretakers for UGX 100-250/jerry can. Intermittent water supply from pre-paid meters is another factor making residents seek alternative water sources – generally unsafe springs, or from vendors and resellers at UGX 200-1,000 per jerry can.
  • Water is just one problem for residents – access roads, waste disposal, expensive school fees and high youth unemployment also mentioned in interviews.
  • Local elections have not happened as mandated because the government fears they will lead to social unrest. This has contribute to resident distrust of local government. 
  • Land ownership is a major barrier to water access and sustainability: there are no clear land records and there are many layers of complexity involving landlords, tenants, the city and traditional authorities.  Changing the land title from private to communal for WASH facilities is essential.
  • Political parties do sometimes co-opt community leaders and demobilise communities, but they can also create political spaces for debate on governance, rules and policies.
  • Strong social capital/networks and trust can help mobilise community power and resources, but can exclude some residents from decision-making processes.
  • NGOs, universities and social movements can play a crucial role in magnifying the ability of communities to act together and achieve liveability goals.

Transition Management for Improving the Sustainability of WASH Services in Informal Settlements in Sub-Saharan Africa—An Exploration. 

Silvestri, G.; Wittmayer, J.M.; Schipper, K.; Kulabako, R.; Oduro-Kwarteng, S.; Nyenje, P.; Komakech, H.; Van Raak, R. (T-GroUP) https://www.mdpi.com/2071-1050/10/11/4052

Key points:

  • “Transition Management” is a participatory planning technique developed for addressing sustainability issues in Europe. The UPGro T-GroUP project is one of the few examples of trying to apply the method in another context: Kampala (Uganda), Arusha (Tanzania), Dodowa (Ghana).
  • The authors identify five contextual factors that account for unsustainable WASH services:
    • Access to water and sanitation in informal settlements comprises a mosaic of formal and informal practices, water sources, sanitation facilities, behaviours and actors.
    • Fragmented and low governance capacity. Low levels of trust between actors.
    • Landownership: unequal and skewed. In Kampala, water and sanitation projects failed due to land conflict; landowners ‘donated’ land for the facilities but after some years later they would take back possession of the land and deny access to the facilities without paying.
    • Public participation in general and WASH services in particular:  more vulnerable community members are excluded
    • Unequal access to WASH services, for example water price varying on social status, with women being disproportionately disadvantaged. Low access to education plays a crucial role.
  • Transition Management was developed based on liberal representative democracies, but this experience in Sub-Saharan Africa suggests that here it needs to be about enlarging and strengthening democratic space  – as a method it is not neutral or universal but shaped by cultural norms and expectations.

:: New UPGro paper :: Characteristics of high-intensity groundwater abstractions from weathered crystalline bedrock aquifers in East Africa

Maurice, L., Taylor, R.G., Tindimugaya, C. et al. Characteristics of high-intensity groundwater abstractions from weathered crystalline bedrock aquifers in East Africa Hydrogeol J (2018). https://doi.org/10.1007/s10040-018-1836-9

From the GroFutures Consortium project and Groundwater Recharge Catalyst project

Background

Crystalline Bedrock aquifers underlie about 40% of Sub-Saharan Africa and can generally sustain low-intensity abstraction. However, pumping rates and dependency is increasing in many areas, particularly for cities like Addis Ababa, Dakar, Nairobi and Dodoma. Projected growth in population and water demand for agriculture, plus the effects of climate change, mean that it is essential to develop a better understanding of the sustainable yields from these types of aquifers.   

Key Points:

  • The study focuses on five groundwater abstraction boreholes, 3 in Uganda, 2 in Tanzania.
  • Long term groundwater records are only available for one of the boreholes and it shows that recharge happens more when the rainfall is more intense, which is often associated with periodic El Niño Southern Oscillation (ENSO) events.
  • Chemical analysis of the water was used to determine the residence times of the groundwater (how long the water has been in the aquifer since it fell as rain). Overall, that most pumped water comes from modern recharge (within the last 10-60 years), so while abstractions are not mining pre-modern groundwater, there may be a component of older water that is coming out.
  • Groundwater abstraction appears to be supported by recharge from across multiple years, rather than just the most recent wet season.
  • The investigation of the five sites shows that long term, high intensity groundwater abstraction is possible from East African weathered crystalline basement aquifers, but the sustainability is constrained, in part, by the high inter-annual variability in recharge. Therefore operation of such pumping stations needs to include sustained monitoring of groundwater levels, pumping rates and rainfall as a minimum.

 

:: New UPGro paper :: Insights from a Multi-method recharge comparison study (Ethiopia)

A new paper from AMGRAF UPGro Catalyst (which has continued with support from the REACH programme).

Walker, D. , Parkin, G. , Schmitter, P. , Gowing, J. , Tilahun, S. A., Haile, A. T. and Yimam, A. Y. (2018), Insights From a Multi‐Method Recharge Estimation Comparison Study. Groundwater. https://onlinelibrary.wiley.com/doi/10.1111/gwat.12801

Key Points:

  • A recharge assessment was conducted at a study site in Northwest Ethiopia (Dangila woreda)
  • 9 groundwater recharge estimate techniques were used with a total of 17 variations were applied to a shallow aquifer
  • These gave a wide range of values from 45mm/year to 814 mm/year
  • The most reliable estimates for reliable recharge are in the range of 280 – 430 mm/year, however the outliers to provide some useful information that helps understand the aquifer

 

The Baseflow Detective looking to uncover the secrets of Tanzania’s rivers

Interview with Hezron Philipo, GroFutures by Sean Furey, Skat Foundation

Hezron Philipo has a BSc in Geology (University of Dar es Salaam, Tanzania), MSc in Water Resources and Environmental Management (University of Twente at  ITC, The Netherlands) and is currently doing his PhD research at Sokoine University of Agriculture in Tanzania as part of the UPGro GroFutures project.

I caught up with him at 41st WEDC Conference in Nakuru, Kenya, where he explained the research that he is doing and what new insights him and his colleagues are uncovering.

Continue reading The Baseflow Detective looking to uncover the secrets of Tanzania’s rivers

New paper helps unravel the mysteries of groundwater recharge in Benin

A new paper entitled: Relationships between rainfall and groundwater recharge in seasonally humid Benin: a comparative analysis of long-term hydrographs in sedimentary and crystalline aquifers has been published by the GroFutures team in collaboration with the GRIBA project (Groundwater Resources In Basement rocks of Africa), Belgian NGO – PROTOS, and Via Water in the Netherlands.

Key Points:

  • Groundwater Recharge – the set of processes that govern how rainwater seeps through soils and rocks to replenish aquifers – is not well understood across much of Africa. It is important to understand because it is central to determine the sustainable use of groundwater resources;
  • The authors analyse three rare sets of long-term (19-25 years) groundwater-level observations from three different, but common, geological settings in Benin;
  • The year-to-year changes in groundwater storage correlate well with rainfall patterns, but there were big differences the relate to the type of geology:
    • In the shallow, sand aquifer as much as 40% of the rainfall becomes groundwater
    • In the deeper sandstone and weathered crystalline rocks, a much lower proportion of rainfall becomes groundwater recharge (13% and 4% respectively)
  • Recharge was found to occur on a seasonal basis; however on a daily basis the groundwater fluctuations are best explained with a threshold of 5-15 mm per day – meaning that only more intense rainfall events lead to recharge.
  • These results are consistent with the growing body of evidence that, in Sub-Saharan Africa, intensification of rainfall associated with climate change may increase groundwater recharge.
  • Because the groundwater recharge is so strongly influenced by geology, it is essential for water resource planning that good geological maps are available and used, and that investment is made into long-term groundwater monitoring of strategic aquifers.

 

New paper: No evidence found of large scale groundwater depletion in major African aquifers

A new paper has been published by the GroFutures team as part of a Special Issue “Remote Sensing of Groundwater from River Basin to Global Scales”

Key Points : –

  • GRACE (Gravity Recovery and Climate Experiment) satellite can be used to estimate changes in water storage on time resolution of 1 month and a spatial resolution of about 450 x 450 km.
  • GRACE can be used to estimate groundwater storage changes where it is the dominant water mass. It is therefore useful in many areas of Sub-Saharan Africa where there are relatively few direct groundwater level measurements.
  • The paper focuses on the major sedimentary aquifers basins, where the majority of Africa’s groundwater resources are to be found. Away from these basins, groundwater storage is 1-2 orders of magnitude less.
  • There is no evidence of continuous long-term declining trends of Total Water Storage (mostly groundwater) in any of the major sedimentary aquifers, which indicates that none are stressed by current abstraction rateshowever it is important to stress that local scale depletion may be occurring but is beyond the resolution of GRACE to detect.

There are also some interesting findings in regard to the combination of GRACE and Land Surface Modelling and how well (or not) they represent groundwater recharge processes in the different basins.

Read the full paper here:

Bonsor, H.C.; Shamsudduha, M.; Marchant, B.P.; MacDonald, A.M.; Taylor, R.G. Seasonal and Decadal Groundwater Changes in African Sedimentary Aquifers Estimated Using GRACE Products and LSMs. Remote Sens. 201810, 904. http://www.mdpi.com/2072-4292/10/6/904

photo: Well for cattle, Songho, Mali, Credit: Emeline Hassenforder. Well for cattle and domestic use. , Songho, Mali.

 

Vote for Roads for Water!

Following an UPGro Catalyst Grant, over the last three years much work has gone into making use of roads for water management. Roads have in many areas an enormous impact on hydrology. Now often negative with roads causing erosion and sedimentation, or creating floods and water logging, this can be turned around to making roads instruments for water harvesting.

Under the RoadsforWater initiative see also www.roadsforwater.org  this approach is introduced in ten countries already contributing to improved water security for more than 2 Million people – hoping to get much higher still. With a global investment in roads amounting to more than 1 Trillion dollar, ‘adding’ water management to road development and maintenance can have an enormous impact.

 We now have very good news and a request to make:

RoadsforWater is among the 11 finalists of the 2017 – Resilience Award! We invite you to vote for this powerful initiative before Monday (15th Jan) Midnight (US Eastern Standard Time)? 

Here is the link: https://goo.gl/R8wbsW – (it is number five on the list).

Thank you for supporting this RWSN-UPGro fostered collaboration. Please also take some time to visit www.roadsforwater.org to find about more about this really interesting and successful initiative.

African aquifers can protect against climate change

Floods and droughts, feasts and famines: the challenge of living with an African climate has always been its variability, from the lush rainforests of the Congo to the extreme dry of the Sahara and Namib deserts. In north western Europe, drizzle and rain is generally spread quite evenly across the year, as anyone who has gone camping in British summer will tell you. But when annual rainfall happens within just a few months or weeks of the year then it is a massive challenge for farmers, towns and industry to access enough water through long dry seasons and to protect themselves and their land from flooding and mudslides when the rains come.

New research[1] suggests that Africa’s aquifers could be the key to managing water better. Professor Richard Taylor at UCL explains: “What we found is that groundwater in tropical regions – and Sub-Saharan Africa in particular – is primarily replenished from intense rainfall events – heavy downpours. This means that aquifers are an essential way of storing the heavy rain from the rainy season for use during the dry season, and for keeping rivers flowing.”

Continue reading African aquifers can protect against climate change

10 things to know about groundwater: #2

Hidden Treasure: 10 reasons to know more about groundwater / 2 priorities to take seriously – briefing note

GROUNDWATER is the water stored in the pores and other openings in rocks below ground. It is a precious resource which must be safeguarded for the benefit of mankind.

recharge

2. However, from a water resource point of view, what matters is how much natural replenishment, or recharge, takes place

Recharge rates vary from a few to hundreds of millimetres per year. In dry regions recharge ranges from zero to a few mm per year.

In humid regions recharge rates represent a higher proportion of rainfall.

Find out more:

What you can do:

Join the conversation through the RWSN Sustainable Groundwater Development community: https://dgroups.org/RWSN/groundwater_rwsn