New field experiments assessing groundwater storage in the Iullemmeden Basin (Niger/Nigeria)

re-posted from GroFutures

New field experiments assessing groundwater storage in the Iullemmeden Basin have recently been completed under GroFutures by a team of early career researchers. From December 2018 to January 2019, Fabrice Lawson from the Université d’Abomey Calavi and IRD in Benin (UAC/IRD), and Jean-Baptist Gnonhoue (IRD, Benin) worked with colleagues, Rabilou Mahaman and Boukari Issoufou from the Université Abdou Moumouni of Niamey (UAMN) in Niger to conduct field experiments applying Magnetic Resonance Sounding (MRS) and Time Domain Electromagnetics (TDEM), to generate in-situ measurements of groundwater storage. Such measurements of groundwater storage are rare despite their fundamental importance to understanding quantitatively the availability and sustainability of groundwater resources.

In total, the team conducted experiments at 26 sites, including 13 in the Dallol-Maouri region in central Niger and 13 in the Goulbi-Maradi region in southeastern Niger, just north of the border with Nigeria. Fabrice and Jean-Baptist led this field research sharing their expertise with their counterparts in Niger. Fabrice and Jean-Baptist (an early career scientist and engineer, respectively) developed their expertise to apply these sophisticated instruments under the tutelage of Jean-Michel Vouillamoz of IRD based at the University of Grenoble, France. The team was also supported by the lead GroFuturesresearchers in the Iullemmeden Basin Observatory, Professor Yahaya Nazoumou at UAMN and Dr. Guillaume Favreau of IRD, Niamey.

Results from field experiments and the subsequent processing and analyses of data will inform not only evaluations of available groundwater resources in these regions of the Iullemmeden Basin but also stress-testing of groundwater development pathways, developed by stakeholders, through numerical modelling. Well done to Fabrice, Jean-Baptist, Rabilou and Boukari!

Combined Benin-Niger GroFutures field team with supporters working in Goulbi-Maradi (left); Early Career scientists under GroFutures, Fabrice Lawson (UAC/IRD, Benin), Jean-Baptist Gnonhoue (IRD, Benin), Rabilou Mahaman (UAMN, Niger), and Boukari Issoufou (UAMN, Niger) running MRS experiments in Goulbi-Maradi (right).

:: 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.

 

Resilience of Rural Groundwater Supplies to Climate Change

Key Note Presentation by Prof. Alan MacDonald @ 1st SADC Groundwater Conference
Keywords: (Drought, Climate, Change, Infrastructure, Groundwater Resources, Resilience).

Alan

“Recent droughts have highlighted the need to understand and forecast the resilience of water supplies to climate variability. Resilience of groundwater supplies is determined by several factors: groundwater storage; long term recharge; permeability; and the infrastructure put in place to abstract groundwater.

“Drawing on recent research from across Africa, mainly funded through the UPGro programme, this talk examines the relative importance of each of these factors for rural drinking water supplies, and attempts to distinguish between the behaviour of the groundwater resource and the water infrastructure.

“A variety of data are presented and evaluated: detailed groundwater level monitoring of springs, wells and boreholes; national survey data of borehole functionality; groundwater residence time indicators; and also information from GRACE and global Land Surface Model.”

Source: Conference Abstract

Photo: SADC-GMI (via Twitter)

Facing the groundwater threats and opportunities in Southern Africa

This week, regional and international water experts have converged on Johannesburg at the 1st Groundwater Conference of the Southern African Development Community (SADC). The event has been convened by the SADC Groundwater Management Institute (GMI) in assocciation with a number of partners including GRIPP

UPGro has a strong presence at the event as part of the build-up to Africa Water Week next month, in Gabon:

  • Opening Keynote: Karen G. Villholth (GroFutures) and Jude Cobbing.
    “Adapting to Climate Change in the SADC Region – A Focus on Groundwater.”
  • Presentation: Theresa Mkandawire (Hidden Crisis) presented “An analysis of hand pump boreholes functionality in Malawi.”
  • Keynote speaker: Alan McDonald. (Hidden Crisis/GroFutures) “Resilience of rural
    groundwater supplies to climate change”
  • Presentation: Thokozani Mtewa,Evance Mwathunga and Wapulumuka Mulwafu.
    (Hidden Crisis) “They gave us breakfast and a good meal’: Roles, perceptions and
    motivations of water point area mechanics in the maintenance of borehole handpumps in Balaka district, Malawi.”
  • Keynote speaker: Dr Callist Tindimugaya “Groundwater and African National Development Strategies”

You can follow the conference on Twitter: #gwconference2018

photo : Prof Theresa Makandawire presenting UPGro Hidden Crisis work in Malawi (credit BGS via Twitter)

 

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.

 

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

GroFutures team bring rain to Niger in the dry season! (maybe…)

re-posted from GroFutures news


Speed Read:

  • Information collected through physical and social science methods was shared and discussed at the GroFutures Annual Workshop in Niger, with partners in and outside the study.
  • Open-source modelling software under FREEWAT platform was successfully piloted for ‘stress testing’ the sustainability of Groundwater Development Pathways accounting for climate and land-use change.
  • New water monitoring has been established to help manage the Iullemmeden Basin, which is shared by Niger and Nigeria

Continue reading GroFutures team bring rain to Niger in the dry season! (maybe…)