[PULA Project] Extreme rainfall and floods in arid regions: replenishment or contamination of water resources?

Lead Research Organisation: University of Aberdeen
Department Name: School of Geosciences

Abstract

While recent research suggests that recharge of groundwater resources in arid regions, including Sub-Saharan Africa, only occurs during extreme rainfall events, these conditions are also associated with the mobilisation of contaminants into surface water and aquifers. Scarcity of clean surface water has already put tremendous pressures on water resources in arid developing countries. Projections of growing populations and more pronounced climatic extremes suggest that sustainable approaches to water resources are urgently needed, but there are key deficiencies in understanding of 1/the mechanisms and timing by which water stores (surface and ground) recharge and get contaminated as a result of heavy rainfall and 2/the associated trade-off between increasing water storage but also potentially of poorer water quality.

The current exceptional ongoing rainy season in Botswana provides an urgent opportunity to study the effects of heavy rainfall on water resources in arid countries. The last heavy rainfall occurred nearly two decades ago and the exceptionally wet conditions have activated potential migratory routes for leachate from dumpsites to ground and surface water. Such point source pollution provides ideal opportunistic conditions for large-scale tracing of flow and contaminant pathways in arid environments.

The proposed work aims to take advantage of this unique prospect to monitor the immediate effect of heavy rainfall and floods on water resources and their transitional hydrologic readjustment towards the dry period, and elucidate whether these events support either or both resources replenishment and contamination. The densely populated Gaborone reservoir catchment is of particular interest because water demand and pollution sources are high and preferential flow pathways in the fractured bedrock result in fast groundwater recharge and contamination. Erosion of shallow soils affects sediment and contaminant transport, as well as geomorphological conditions which in turn impact on recharge patterns.

We will utilise the unique opportunity to evaluate the crucial link between water quantity and quality, often investigated separately, through an integrated approach that combines hydrologic monitoring, temporal geophysical imaging, geomorphological mapping and natural tracer experiments (leachate and stable water isotopes) with modelling. Experiments will span the ongoing wet season and its transition to the following dry season. Water monitoring and sampling will focus on existing ground and surface water points across the catchment as well as dams and potential pollution sources at different spatial and temporal scales. Integrating the datasets into the modelling framework will allow for characterising and quantifying the contribution of extreme rainfall events to water resources replenishment and contamination.

The project team is composed of UK and African scientists with specialisations in hydrogeology, surface water hydrology, geophysics and sedimentology and water governance stakeholders. Research will benefit from a hydrometric monitoring in place and in-kind sample collection pre-award, which will be expended during the project.

The overall research outcomes will be 1/a greater understanding of the key processes governing flood-induced water resources replenishment and contamination in arid developing regions and 2/an increased ability of water resources stakeholders to adapt management and policy to the foreseeable increase in hydrological extreme events.

The new science generated will impact both the academic community interested in new methods and knowledge with regards to hydrological processes under changes, and the governance sector in arid (sub-Saharan) regions in need of adaptive water management strategies able to cope with both short and long term effects of climate change. Students and project partners will receive training and early career researchers will build their research portfolio.

Planned Impact

This project will have various academic and socio-economic impacts on four groups of beneficiaries:

1.Inhabitants of Botswana and African arid regions: A significant proportion of the population of Botswana, and of the wider arid part of sub-Saharan Africa is dependent on vulnerable water resources in low-storage fractured basement rocks that are exposed to increased frequency of extreme rainfall events. On the short term, the project will impact the local people through enhanced awareness of the issues surrounding water resources from direct interactions in the field and from participation of representatives of local community water associations to the project stakeholder workshop. On the mid to long-term, the outcome of the research will have wider impact on people from arid regions by contributing to increased knowledge of climate impact on water resource therefore a more sustainable provision of safe water, hence improving their well-being.

2.Local and regional authorities (governance): The project will contribute to improve water governance and policy through provision of evidence-base for (i) revision/upgrade of the DWA groundwater monitoring network from identification of catchment areas most sensitive to flood-induced recharge and contamination; (ii) proposition/prioritization for reclaim of major contaminated sites; (iii) development of a specific system for monitoring anthropogenic contamination around point source pollution risk areas. The new knowledge on the timescale of response of water resources to extreme rainfall and floods will be useful to the decision-makers and environmental manager to adapt their response/mitigation capacity to hydrological disasters. The impact on the Botswana water governance sector will be achieved through (i) early involvement of the Department of Water Affair (DWA, project partner) in the design of the field surveys and sampling routines as well as selection and instrumentation of new relevant water monitoring points and (ii) participation national and regional representatives of DWA to the final workshop delivered.

3.General public in the UK, Africa and beyond: We aim to raise public awareness on how important and fragile the water resources are in arid regions and how they are related to climate variability and extremes. Throughout the project we will work with the Public Engagement with Research Unit at UoA, which coordinate and deliver a range of public facing events. We plan to hold an event at the 2018 British Science week, which takes place annually in March. In particular, we will target both adults and children, with presentations based on photos and videos acquired during the fieldwork. In addition, a webpage will be created on the University of Aberdeen's website with information and news updates and we will approach UK and Botswana media for coverage of major discoveries.

4.Academic communities: The international academic community will learn from the findings that will provide light on key processes that determine water sustainability in developing arid countries subject to increasing frequency and magnitude of climate extremes. The impact will be achieved through an international conference presentation, open-access, high-impact journal publications, and storage of the project data in the RCUK Data Centres. Our Partner IMWI will provide synergies with parallel ongoing water research initiatives in Botswana and Southern Africa that they are leading, which will contribute to increase the regional impact beyond the strict project team and studied area. In addition, the research will contribute to train and inspire five students (BSc and MSc) from the partner BIUST, who will be involved in all fieldwork activities and data analysis, and will complete their dissertations/thesis as part of the project. The early career researchers through coordination of workpackages and tasks will develop their leadership skills and portfolio, hence their career development.
 
Description Project hydrological and sedimentological monitoring results showed that:
(1) the high rainfall of 2017 was at least a decadal event;
(1) groundwater levels have rapidly risen following the 2017 floods, by up to 20 metres, and are remaining at high levels months after the event;
(2) the water table rise is higher than following previous 'normal' flood events;
(3) downstream major dams, which reached full capacity within a couple of weeks for the first time in a decade, the water table rise continues months after the event, whereas other areas (upstream dams) show decline at a normal rate for dry season;
(4) groundwater mineralization has temporarily increased in rural areas upstream dams, while mineralization increase continues in peri-urban areas downstream dams;
(5) at local scale, a dilution of leachate plumes is observed downstream the major landfills;
(6) chemical contaminant indicators (metals) show a minor increase post floods;
(7) some metal elements present in recent sediment associate with the flooding in the dam located near the outlet of the catchment are correlated with those measured in ground and surface water suggesting that dams sediments could be used as proxies for long-term reconstruction of catchment-scale contaminant dynamics associated to flood and drought cycles.
These initial findings provide valuable conceptual insights on the understanding of extreme flood impacts on groundwater in arid regions under complex hydrogeological and landuse settings. They overall suggest that the 2017 event in Botswana triggered both a major, rapid recharge event over the catchment and delayed, slower recharge downstream major dams (probably from the dams themselves), this along with possible contaminant migration in groundwater in peri-urban areas, yet concurrently diluted by recharge water volumes resulting in near-steady concentrations. Ongoing continuing analysis of research results and follow on project Connect4WR are providing further quantitative knowledge of groundwater-flood interactions, recharge and contaminant migration processes which will be translated into guidance for assisting effective groundwater management, including managed aquifer recharge approaches.
Exploitation Route Our impact funding will be useful to:
- water stakeholders (governance and users) for improved management of water resources during floods;
- the academic community by providing evidence of the role of floods to groundwater recharge and contaminant transport in arid regions subject to increased hydrological extremes.
Sectors Agriculture, Food and Drink,Communities and Social Services/Policy,Environment,Government, Democracy and Justice

 
Description The project findings are being used by the beneficiaries of the research programme, which include: (1) local communities; (2) stakeholder groups (water authorities, water users, planning agencies, NGOs). Through the Kgotla (local chief house) meetings involving local representatives of the public, local communities have increased their awareness of processes and risk associated to floods as well as the opportunities with regards to better water storage and quality. This has been materialised by behavioural change expressed by meeting participant, however evidence for materialisation in the ground might take longer time to be clearly observed. Through close involvement in the implementation of the research by water governance agents, government staff and colleague have enhanced their training in state of the art hydrological data acquisition and interpretation as well as their awareness of the impact of extreme floods on water resources, particularly the positive role on groundwater recharge and negative role with respect to mobilisation of local point source contaminant (eg dump site and landfill). This is leading to new inputs in ongoing review of national policy documents such as the National Master Plan for Wastewater and Sanitation and the Groundwater monitoring network in the Ramotswa area.
First Year Of Impact 2018
Sector Communities and Social Services/Policy,Environment,Government, Democracy and Justice
Impact Types Cultural,Societal,Policy & public services

 
Description Dr. Franchi invited as panelist in the technical committee established by OKACOM for the Cubango/Okavango Environmental Monitoring Framework (EMF) project.
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description Reporting of Pula Project results and achievements at government Cabinet Level.
Geographic Reach National 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
Impact Reporting of project results to the Botswana government cabinet led to increased awareness of risk associated to floods beyond direct damages, but also in terms of water quality deterioration. It also raise awareness of the importance of management of dams for smoothing flood impacts and favouring groundwater recharge. This is being materialised through current review of the National Master Plan for Wastewater and Sanitation of the Groundwater monitoring network in the Ramotswa area.
 
Description Training of government hydrologist to state of the art water quality sampling and hydrological interpretation
Geographic Reach National 
Policy Influence Type Influenced training of practitioners or researchers
Impact Training of Mr Alfred Petros, hydrogeologist at the Botswana Department of Water Affairs has raised awareness in the need for better management of floods and in particular the role of groundwater for water resources replenishment and higher resilience to contamination and droughts. This is being materialise through the inputs of Mr Petros in the revision of the National Master Plan for Wastewater and Sanitation and the Groundwater monitoring network in the Ramotswa area.
 
Description Connect4 water resilience: connecting water resources, communities, drought and flood hazards, and governance across 4 countries in the Limpopo basin
Amount £252,352 (GBP)
Funding ID NE/S005943/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 11/2018 
End 07/2020
 
Title New approach on the study of floods-droughts via characterization of dam sediments: one of the first attempt in arid environments. 
Description See above 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact Publication in progress. 
 
Title Research questionnaire prepared for the kgotla meetings. 
Description see above 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact Research publication in progress. 
 
Title EIDC open-access dataset on flood sediment records 
Description Data resource title: Sediment records of the 2016-2017 flood from Notwane dam, Upper Limpopo basin, Botswana. NERC Environmental Information Data Centre. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact No known impact yet as dataset was only published on 2019-11-18. 
URL https://catalogue.ceh.ac.uk/documents/022b3fff-55d7-46f5-b11f-2f7366e508b0
 
Title EIDC open-access dataset on water quality 
Description Data resource title: Water resources quality data following extreme rainfall and floods in the Gaborone catchment, Upper Limpopo basin, Botswana. Deposit reference: EIDCHELP-27509. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? No  
Impact No impact yet as dataset will be open-access from EIDC on 1/6/19 following a 3 month embargo. 
URL https://catalogue.ceh.ac.uk/documents/c7793128-1961-45d5-aa18-5f023116784b
 
Title Integrated water quality and quantity, geophysical monitoring and sedimentological database 
Description The research produced an extensive, new and unique database of integrated water quality and quantity, geophysical monitoring data and sedimentological data at unprecedented high spatial and temporal resolution for this region and providing environmental records of the impacts of an extreme hydrological event. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? No  
Impact No impact yet - the database is currently in the process of being structured and quality check for integration into the NERC EIDC open-access datacentre. As for now (March 2019), all water quality data have been transferred. 
 
Description Collaboration with the Geological Survey of Canada for sediments 14C radiocarbon dating 
Organisation Natural Resources Canada
Department Geological Survey of Canada
Country Canada 
Sector Public 
PI Contribution F Franchi, project CoI, established a collaboration with Dr. Jason M. E. Ahad from the Geological Survey of Canada with respect to the project 14C radiocarbon dating.
Collaborator Contribution The collaboration provided expert advise for 14C radiocarbon dating.
Impact 14C radiocarbon dating dataset for sediments sampled at part of the project. Draft publication in progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Anglia Ruskin University
Country United Kingdom 
Sector Academic/University 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Dabane Trust
Country Zimbabwe 
Sector Charity/Non Profit 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Eduardo Mondlane University
Country Mozambique 
Sector Academic/University 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Government of Mozambique
Country Mozambique 
Sector Public 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Mozambique Red Cross
Country Mozambique 
Sector Charity/Non Profit 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation University of Birmingham
Country United Kingdom 
Sector Academic/University 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation University of Venda
Country South Africa 
Sector Academic/University 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description Collaboration with the Universities of Birmingham, Anglia Ruskin, Venda, Eduardo Mondlane and non academic partners for development and implementation of new upscaled research in the Limpopo River Basin (project Connect4WR) 
Organisation Water Research Commission
Country South Africa 
Sector Public 
PI Contribution JC Comte brought this collaboration together in order to develop wider research at the scale of the Limpopo river basin based on the current award and other active initiatives by the partners. JC Comte coordinated the team towards new research proposal submission to NERC SHEAR Catalyst call, which was later awarded (June 2018 - see section Further funding).
Collaborator Contribution Partners provided various technical and administrative inputs to the proposal.
Impact In progress.
Start Year 2018
 
Description 10 July 2018: kgotla (chief house) meeting in Ramotswa, Botswana. 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Policymakers/politicians
Results and Impact The event took place on 10 July 2018 at the kgotla (chief house) Ramotswa, Botswana chaired by the Paramount Chief Kgosi Mosadi Sebogo of the Balete People. Presentation of the student's project related to PULA and questionnaires.
Year(s) Of Engagement Activity 2018
 
Description 30 July 2018: kgotla (Chief house) meeting in Lobatse, Botswana 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Policymakers/politicians
Results and Impact 30 July 2018: kgotla meeting in Lobatse, Botswana chaired by the local Chief (customary court president). Presentation of the student's project related to PULA and questionnaires.
Year(s) Of Engagement Activity 2018
 
Description 31 July 2018: kgotla (Chief house) meeting in Old Naladi, Botswana 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact 31 July 2018: kgotla (Chief house) meeting in Old Naladi, Botswana, chaired by the local Chief (customary court president). Presentation of the student's project related to PULA and questionnaires.
Year(s) Of Engagement Activity 2018
 
Description Engagement of water stakeholders in project meetings (launch and final) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact The stakeholder meeting as part of the project kick-off meeting involved a range of academic and non academic stakeholder. The involvement in particular of water resources officers from the Botswana Department of Water Affairs fostered very useful discussions on how to fine tune the implementation of research activities and the production of research outputs in order to be easily integrated by them for policy making in relation to management of water resources and flood related issues. The meeting also strengthened the collaboration with the stakeholders and contributed to secure further NERC funding involving tight stakeholder collaboration (see section Further Funding)
Year(s) Of Engagement Activity 2017
 
Description Workshop on floods at the University of Aberdeen's May Festival, May 25-27, 2018 engaging the general public, including schools. 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact J Geris set up several workshops on floods at the Aberdeen University May Festival 2018. The specific activities were financially supported by the award. Activities included: A public talk on "Extreme Rainfall and Floods in Arid Regions"; A public appearance with hands-on demonstrations on "The value of nature-based solutions for flood prevention" during the 'Hall of Mayhem' event of the festival; Two primary school events on "What happens when it rains" during the UoA Mayfestival.
Talks and physical demonstrations (flood stand) raised interest and questions, especially among school kids.
Year(s) Of Engagement Activity 2018