Groundwater flooding: Groundwater community recovery following an extreme recharge event.

Lead Research Organisation: Roehampton University
Department Name: Life Science


This winter (2013-14) has been the wettest in the UK since records began resulting in extremely high groundwater levels and very extensive groundwater flooding, particularly in chalk aquifers. The exceptionally high intensity of flooding and water movement through the aquifers is expected to result in changed nutrient concentrations, including carbon. We think that these changes will have major effects on the groundwater ecosystem which, in addition to the chemical and physical environment, comprises microbial biofilms, microfauna (e.g. Protozoa, rotifers), and macroscopic invertebrates dominated by crustaceans such as copepods and Niphargus (blind shrimp-like animals). Most groundwater organisms are unique to this habitat and, in the UK, have been present for many millions of years. They mediate processes such as nitrogen recycling and thus they impact the quality of a vital source for drinking water.

We think that during flooding, nutrient supplies will initially decrease due to dilution and that flow rates will increase, potentially stripping microbial biofilms and associated microfauna from the sediments and dislodging larger organisms into the water flow. This will lead to an initial reduction in biomass at each trophic level although it will not alter the overall shape of the biomass pyramid. We also expect ecosystem respiration and species and/or functional diversity to be low during flooding. When the flood ends we think that microbial biofilms, protozoa and small metazoa will recover quickly because they reproduce rapidly but that larger animals will recover more slowly if they cannot find shelter from the flood. This may result in a change in shape of the biomass pyramids. We will test these ideas by tracking the recovery of the groundwater ecosystem through space and time. We will do this by collecting samples to measure the food supply (dissolved organic carbon and other nutrients), count and identify the inhabitants of the groundwater ecosystem and also determine how ecosystem function changes by measuring respiration rates and microbial activity. We will collect samples in two separate flooded chalk aquifers at fortnightly intervals over a seven month period so that we can monitor changes in the community; we expect these to be rapid. We will use specialised equipment to measure microbial respiration and count the smallest organisms (bacteria). This extreme event permits a uniquely important case study because it will provide a baseline against which future extreme events (e.g. flooding and drought) in groundwaters can be measured and will enable us to compare the responses of groundwater ecosystems to stressors with those of other aquatic ecosystems.

We hope to use the data collected in this project to apply for larger grants, possible topics for these grant applications include combining data generated in this Urgency grant with laboratory experiments that will enable us to calculate the extent to which different Groundwater assemblages (e.g. with or without macrofauna) are able to metabolise dissolved organic carbon/ nutrient loadings and thus, provide effective water quality ecosystem services of substantial ecological and economic impact to the UK.

Planned Impact

Those who will benefit from the research

Scientists including Ecologists and Biogeochemists:
Our findings will improve the current very limited understanding of the responses of groundwater ecosystems to flooding and provide a benchmark for future extreme groundwater flooding events, providing an essential resource to the scientific community. They will enable a comparison with ecosystem responses to stressors in surface systems and be used to examine groundwater ecosystems and their response to flooding in the context of general ecological theories e.g. the Metabolic Theory of Ecology. Our data will also be of benefit to interdisciplinary scientists because it will shed light on the interactions between water chemistry, microbial biofilms and macrofauna and how these are affected by flooding.

Government Agencies, Environmental Consultancies and Water Industries:
The results of this project will provide regulators and decision makers in government agencies, environmental consultancies and water industries with a picture of how groundwater ecosystems will respond to one aspect of a changing climate. Our results will feed into mitigation strategies for future extreme events and provide policy makers and stakeholders with data pertaining to the responses of GW ecosystems to flooding and the impact this may have on GW quality.

The General public:
There is a clear concern as to the impact of groundwater flooding on human property and water quality and the general public will need to be appropriately informed of the results of our research.

How they will benefit from our research
Scientific community: The knowledge gained from our study will drive future research directions, and inform research into understanding the ecological response of ecosystems to future climate extremes.
Government Agencies, Environmental Consultancies and Water Industries and general public: Close collaboration with our EA Project Partner and with other stakeholders such as Natural England and river trusts ensures that the new understanding of responses of groundwater ecosystems to flooding will inform decision making in the management of groundwater ecosystems. Our results will provide policy makers and stake holders with an estimate of the impact of flooding on GW ecosystems, these results are transferable and can provide essential information for predictions of future impacts of global change and anticipated increased frequency of flooding extremes.

Measures to ensure benefits from this research
The dissemination of the results of this project will benefit strongly from our Environment Agency project partner who will ensure that our results are highlighted within their organisation. The involvement of the investigators in national and international research and stakeholder networks (e.g. BES, SEFS, UNESCO, EGU , BHS) will also benefit dissemination. We will also organise a one day UK workshop targeted at academics, research institutes, water companies, environmental consultants and managers, decision and policy-makers, government agencies and laypersons.
We will develop a project website (hosted at UR) with content for scientists, decision makers and laypersons. A project summary will be published here, outlining (in layperson's terms) the significance and key findings of our work. Following the urgency phase of the project, results will be published in high-impact, peer-reviewed journals as well as in popular periodicals and newsletters (e.g. NERC Planet Earth, Freshwater Biological Association newsletter). We will present our results at major international and UK conferences plus invited research seminars at universities and other research institutes.
We will also engage with schoolchildren (keystage 2; water cycle). JR is a STEM ambassador and will disseminate our findings in local schools. The project findings will form part of the science week hosted by UR where we showcase our research to the local community.


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publication icon
Reiss J (2019) Groundwater flooding: Ecosystem structure following an extreme recharge event. in The Science of the total environment

Description We found that Dissolved organic carbon (DOC) was higher shortly after the recharge event and then declined. The DOC peak was followed approximately 6 weeks later by a peak in bacterial abundance. Protist biomass and macrofaunal abundance increased with increasing distance from the recharge event.
However, even in the early months of the study macrofaunal abundance was higher than that found in a study a few years earlier. Although macrofaunal abundance increased over time, biomass was lower because juvenile stygobites were more numerous, possibly as a result of reproduction following increased food availability.

Body mass-abundance plots demonstrated that communities in both aquifers exhibited a strong size structure.
Exploitation Route Our findings provide evidence that groundwater food webs respond to increased levels of dissolved organic carbon and other nutrients. They may have the ability of buffer the increased inputs of carbon to groundwater expected under climate change. This is important because it suggests that groundwater food webs may impact the water quality of this widely used resource. These findings could be further explored and eventually used to incorporate groundwater ecosystems into the management and monitoring of groundwater resources.
Sectors Environment,Other

Description I have used our findings (and those of others) to push for the inclusion of groundwater ecosystems into any new iteration of the EU Groundwater Directive. I have done this by organising and taking part in a session on Groundwater Ecosystems at the EU-CIS- WFD- groundwater working group meeting in Malta 2017and following up in Nottingham 2017.
First Year Of Impact 2017
Sector Environment
Impact Types Societal,Policy & public services

Description MSCA-ITN-2014-ETN
Amount € 3,500,000 (EUR)
Organisation European Economic Community 
Sector Public
Country European Union (EU)
Start 01/2015 
End 12/2018
Description UK-Israel Synergy Programme
Amount £7,000 (GBP)
Funding ID 317868924 
Organisation British Council 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2018 
End 02/2018
Description Research collaboration with Israel 
Organisation Ben-Gurion University of the Negev
Country Israel 
Sector Academic/University 
PI Contribution Workshop to explore collaborative possibilities between our two institutes
Collaborator Contribution Workshop to explore collaborative possibilities between our two institutes
Impact None yet
Start Year 2018
Description Discussions with end users 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Discussions with small groups from e.g. Environment Agency, UK onshore oil and gas
Year(s) Of Engagement Activity 2015,2016
Description Science week (Roehampton) 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact We described our project to members of the public and to students who attended the Roehampton science week. Questions were asked by the attendees.
Year(s) Of Engagement Activity 2015