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

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

Safe water in towns and peri-urban areas: challenges of self-supply and water quality monitoring

Millions of people in towns and cities across Sub-Saharan Africa depend on groundwater day-to-day – but is it safe to drink? How can we measure the safety quickly, cheaply and accurately?  In this RWSN-UPGro webinar, Dr Jenny Grönwall (SIWI/T-GroUP) and Dr Dan Lapworth (BGS) present the latest updates on their research into urban groundwater monitoring and use, and how it can be improved.

Water monitoring upgraded in Upper Great Ruaha, Tanzania

re-posted from GroFutures

The GroFutures Team, working with the Tanzanian Ministry of Water and Irrigation, expanded monitoring infrastructure in the Upper Great Ruaha Observatory (UGRO) to include interactions between groundwater and surface water.

An outstanding question regarding the sustainability of groundwater withdrawals for irrigation and drinking-water supplies is whether groundwater in the agriculturally intensive lowlands is replenished by river flow, sustains river flow, or both depending upon the season.

Continue reading Water monitoring upgraded in Upper Great Ruaha, Tanzania

Groundwater monitoring established in the Upper Great Ruaha Basin, Tanzania

Re-posted from GroFutures.org

The GroFutures team at Sokoine University of Agriculture (SUA, Tanzania), led by Japhet Kashaigili (SUA) with support from PhD students, Hezron Philipo (SUA) and David Seddon (UCL), established in July (2017) a groundwater-level monitoring network in the Upper Great Ruaha Basin Observatory in southern highlands of Tanzania.  This area is part of the Southern Agricultural Growth Corridor of Tanzania (SAGCOT) where increased use of groundwater and surface water is anticipated to support agricultural production.  Constructed monitoring wells at depths ranging from 18 to 32 m below ground were drilled using a PAT-DRILL 421 rig. The team also instrumented monitoring wells recently constructed by project partners at the Rufiji Basin Water Board (RBWB) in the Tanzanian Ministry of Water and Irrigation.

The new monitoring network comprises an upstream location at Chimala at the base of an escarpment and a downstream location at Mbarali within the alluvial plain. A monitoring well at Chimala Secondary School was installed into coarse unconsolidated sands and gravels to a depth of 26 m. This monitoring well is linked to both an additional monitoring well at Usangu Secondary School and a river gauge. Both monitoring wells are equipped with automated dataloggers providing hourly groundwater-level measurements. A third borehole was constructed at Chimala Primary School though no groundwater was encountered up to a depth of 30 m. At Mbarali, two monitoring wells were constructed on the St. Ann’s Secondary School and now form a transect of 4 monitoring wells as the team also instrumented two monitoring wells recently constructed by the RBWB at Rujewa at Mbarali Secondary School and Jangurutu Primary School.

The new infrastructure is expected to reveal for the first time the dynamics between groundwater and surface water in the Upper Great Ruaha sub-catchment of the Rufiji Basin and answer key questions around the nature of groundwater recharge and whether seasonal river flow recharges  groundwater or groundwater sustains river flow. Further work will also seek to ensure that this observatory is equipped with both tipping-bucket rain gauges to record sub-daily (hourly) rainfall intensities and soil-moisture probe arrays to better understand how intense rainfalls are transmitted through alluvial soils.

Promising new groundwater pollution sensor – New UPGro paper published

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Field test set-up and data output from the MFC biosensor monitoring. A) The diagram shows an aerial view of the system configuration and distance between sensing system and data collection system. B) MFC1 and MFC2 were biosensors placed on the well; MFC3 and MFC4 were control biosensors placed in a vessel simulating the groundwater well. MFC3 and MFC4 were located in a room close to the well and the arrow indicates when they were intentionally contaminated. Monitoring of the sensors contained in the well lasted for 60 days obtaining the same trend as for the period shown.

Shallow groundwater wells, are the main source of drinking water in many rural and peri-urban communities.

The quantity and variety of shallow wells located in such communities make them more readily accessible than private or government operated deep boreholes, but shallow wells are more susceptible to faecal contamination, which is often due to leaching pit latrines.

For this reason, online monitoring of water quality in shallow wells, in terms of faecal pollution, could dramatically improve understanding of acute health risks in unplanned peri-urban settlements.

More broadly, inexpensive online faecal pollution risk monitoring is also highly relevant in the context of managed aquifer recharge via the infiltration of either stormwater or treated wastewater into the subsurface for aquifer storage and recovery.

 To tackle this challenge, IN-GROUND – an UPGro Catalyst Project – trialled four different types of Microbial Fuel Cell (MFC) water quality biosensor in the lab (Newcastle University, UK) and in the field (Dar Es Salaam, Tanzania).  

While further work is needed, the results provided proof-of-concept that these biosensors can provide continuous groundwater quality monitoring at low cost and without need for additional chemicals or external power input.

 Full details of the work can be founded in this open access paper: Velasquez-Orta SB, Werner D, Varia J, Mgana S. Microbial fuel cells for inexpensive continuous in-situ monitoring of groundwater quality. Water Research 2017, 117, 9-17. 

 For more details contact Dr Sharon Velasquez-Orta 

Piecing together Africa’s groundwater history

The UPGro programme, supported by AfriWatSan & ESPRC, conducted a pan-African capacity-strengthening and knowledge co-production workshop at Sokoine University of Agriculture in Morogoro, Tanzania from the 10th to 12th of February, 2017.

40 participants from 12 countries in Africa took part and analysed multi-decadal, groundwater-level data (“chronicles”) from 9 countries including Benin, Burkina Faso, Ghana, Niger, Sénégal, South Africa, Tanzania, Uganda and Zimbabwe.

Continue reading Piecing together Africa’s groundwater history

BBC: ‘Good vibration’ hand pumps boost Africa’s water security

Published: http://www.bbc.com/news/science-environment-39077761

The simple up-and-down motion of hand pumps could help scientists secure a key water source for 200 million people in Africa.

Growing demand for groundwater is putting pressure on the resource while researchers struggle to accurately estimate the future supply.

But a team from Oxford University says that low-cost mobile sensors attached to pumps could solve the problem.

Their study shows that pump vibrations record the true depth of well water.

Continue reading BBC: ‘Good vibration’ hand pumps boost Africa’s water security