Brighid Ó Dochartaigh has been awarded the Younger Medal by the Geological Society for her outstanding contribution to the hydrogeological community leading the development of the . The atlas was created alongside the International Association of Hydrogeologists, with contributions from over 60 African groundwater scientists from 2014 to 2022.Ìý

A widely used online resource, the atlas provides groundwater information for Africa and acts as a gateway to access additional resources. It contains country profiles on the hydrogeology of 51 countries in Africa, including downloadable geological and hydrogeological maps. The sits alongside the atlas, providing access to PDFs of thousands of documents on groundwater in Africa, many authored by Brighid. Working with in-country co-authors, she also led the production of the suite of hydrogeology maps that are freely available for use in GIS applications.Ìý

Prof Charlotte Watts, chief scientific advisor to the Foreign, Commonwealth & Development Office, referred to the atlas as an example of innovative science for development at the 2018 UN Annual Forum on Science, Technology and Innovation for the SDGs.Ìý

The medal was accepted on Brighid behalf by BGS Head of Groundwater, Prof Alan MacDonald, in London on November 19.

My career has been ended early because of long covid, which has left me too sick and disabled for work. That experience makes it particularly special to me to be this year recipient of the Younger medal.Ìý

But the main reason I feel so honoured is for the work this award recognises: the Africa Groundwater Atlas. It been so much a team effort, by colleagues across BGS and other UK organisations, and hydrogeologist colleagues in countries across Africa. Ìý

One of the biggest reasons I value the atlas is for how much support there has been for its development from the start from colleagues in Africa. Their early support validated how useful a resource it could be and encouraged us in its development. Since the launch of the atlas, we’ve seen so many examples of the positive impacts it having on the work of improving understanding sustainable use, and management of groundwater.Ìý

I’m very happy that the atlas continues to be developed by my BGS colleagues, and I hope it will be around for many years to come. I’m proud to think of it as an important legacy of my career. And I’m very thankful to the Hydro Group for recognising the work of the atlas with the award of this medal today.

Brighid Ó Dochartaigh.

Throughout her career, Brighid developed many excellent and useful hydrogeological tools, datasets and reports.  The Africa Groundwater Atlas is the jewel in her crown, a fabulous resource used by many throughout the world and developed in partnership with groundwater colleagues throughout Africa.  I am really delighted that Brighid has been award the Younger Medal — a very deserving recipient.

Alan MacDonald, BGS Head of Groundwater.Ìý

Natural flood management (NFM) has become a key aspect of UK policy to reduce the risk of flooding, a hazard that is expected to increase under future climate-change scenarios.

What is natural flood management?

NFM seeks to control flooding by reducing or slowing the flow in river catchments using natural approaches. These include measures such as:

• planting trees to enhance infiltration and catchment roughness
• installing leaky wooden barriers within streams to create temporary surface water storage
• re-meandering rivers to reconnect them to their flood plains

Current understanding of natural flood management

There is growing pressure to change the way landscapes are managed at large spatial scales to respond to the climate and biodiversity crises. Despite its newfound popularity in UK policy, there are still uncertainties about the effectiveness of NFM at . This is particularly true for measures that are dispersed across catchments, such as land-use change through afforestation or improvements to soil quality.  Understanding how water is stored and released within catchments is vital for predicting the effects of these changes on both floods and droughts, as well as a host of other co-benefits such as biodiversity and agricultural productivity.

Recent work by Heriot-Watt University, the University of Edinburgh, BGS and the University of Dundee has started to look at these questions at the internationally important at the in the Scottish Borders.

Why is more research needed?

The infiltration of water into the subsurface is a key area of research in NFM including:

• how water infiltrates different soils
• the effect of different soil properties on infiltration rates
• the

In addition to understanding how easily water infiltrates, we also need to know how much water can infiltrate and where it goes — in other words, how much water can be stored? There has been much less research on quantifying catchment storage and the role of deeper catchment storage in the context of NFM, despite its potentially .

The effects of soils and geology on catchment storage

Using multiple methods, including water-level monitoring and stable isotopic tracers, our research estimated water storage across nine subcatchments and correlated the findings with catchment properties such as soil type, land cover and geology. We found that in controlling catchment water storage, suggesting that the effects of changing forest cover are masked by more dominant soil and geological properties.

There are, of course, caveats to the work: we only looked at existing, mature conifer forests and only considered the effect of trees on storage. The impacts of trees on surface roughness and broadleaved trees, which are the main type planted by this and many other NFM projects, were not considered. While the differences are probably minimal, these questions need to be tested through further research. Our findings are, however, consistent with other work looking at and in Eddleston and .

Implications for natural flood management

These findings have two significant implications for NFM. The first is to add further criteria for determining the planting of the ‘right trees in the right place’. This storage perspective suggests that tree planting needs to be targeted at areas where potential storage is high but infiltration rates are low, such as highly compacted or degraded soils in relatively permeable catchments. The second is the need to understand dominant catchment controls on runoff in any NFM scheme, which means getting better knowledge of hydrological processes within catchments and their representation within models. We are exploring this second implication in a follow-up study combining stream flow data and water tracer data into a hydrological model, to see if this improves model outputs and therefore understanding of land use change in the catchment.

There is growing pressure to change the way landscapes are managed at large spatial scales to respond to the climate and biodiversity crises. Gaining a better understanding of catchment water storage across different environments is likely to be vital for predicting the multiple benefits and risks of nature-based solutions such as NFM. Future research using both empirical and modelling approaches needs to incorporate these perspectives to underpin effective future management strategies.

About the authors

Leo Peskett

Assistant professor in physical geography

Heriot-Watt University

Leo’s work focuses on evaluating the effectiveness of nature-based solutions in the land and water sectors and engaging with policymakers at international to local levels to bridge research and policy. His recent research has concentrated on:

• the integration of land and water management in the UK
• the impacts of land use on runoff in a natural flood management context
• the use of the natural capital approach in environmental management

Prior to academia, Leo spent a decade heavily involved in the development of global policies to reduce carbon emissions from deforestation (REDD+) and related climate change policies, working with the Overseas Development Institute, UN agencies and governments in the global North and South.

The problem

Human activities such as inefficient nitrogen fertiliser application have led to excess nitrogen concentrations and the continued degradation of coastal and fresh water around the globe (Figure 1). The effects of human activity on the nitrogen cycle are particularly strong across the United States of America, with the production of nitrogen-based fertiliser a major cause of the nutrient pollution that persists across the country. Although the associated environmental degradation is thought to cost the country billions of dollars a year and reducing human-derived nitrogen inputs is vital for restoring a functioning ecosystem, efforts such as those introduced by the have often resulted in slower than anticipated water-quality improvements. Correctly identifying and estimating all processes that can act as sources or sinks of nitrogen is thought to be an important step in reducing inputs.

The science

The USA has one of the largest freshwater abstraction volumes per capita in the world, with major uses for fresh water including irrigation, thermoelectric power, and public water supply. For this project, we used publicly available datasets on countrywide withdrawal volumes and nitrate (NO₃) concentrations for both surface water and groundwater. We found that freshwater abstraction will temporarily retain any associated NO₃ in the abstracted water from the aquatic environment.

We estimated the abstraction NO₃ flux for the contiguous United States to be 417 kilotons of nitrate nitrogen per year (kt NO₃-N yr^-1) and found large disparities between county-level abstraction flux estimates (Figure 2). We assessed the significance of the national-level abstraction NO₃ flux estimate in the context of pre-existing US nitrogen budgets through comparison to other nitrogen budget components and found our estimate to be equivalent to 57 per cent of total denitrification estimates.

The results

Our research indicates that freshwater abstraction can act as a significant temporary retention mechanism, meaning that it temporarily delays the delivery of nitrogen from the land to the oceans, hence it should be considered when developing nitrogen budgets.

When considering this mechanism, it worth noting that leaking US water mains cause an average of 16 per cent of the water initially entering the distribution network to be lost the environment. We used publicly available data to estimate the release of NO₃ to the environment in association with this leakage at around 7 kt NO₃-N yr^-1 (across the contiguous United States). Although this estimate is insignificant to national-level nitrogen cycling, county-level fluxes vary greatly (Figure 3), with the magnitude of the flux having a positive correlation with urbanisation.

The localised significance of leakage-derived NO₃ is highlighted by the exceedance of these fluxes over agricultural fertiliser nitrogen inputs across some counties (Figure 4) and suggests that these fluxes should be incorporated alongside abstraction NO₃ fluxes within nutrient budgets and considered when developing nutrient-management strategies. Future work should aim to further resolve these fluxes, both across the United States and around the world.

My PhD research

As part of my PhD thesis, I recently published a paper on investigating the effects of freshwater abstractions and mains water supply leakage upon nitrogen cycling across the United States (Flint et al., 2022).

My ongoing research will investigate the potential for both mains water leakage and the use of phosphate-dosed water outdoors at domestic residences to act as sources of phosphorus across the United States. I will also be investigating the potential for the stable oxygen isotope composition of phosphate to identify phosphate-dosed drinking water as a source of phosphorus within the environment and to assess the processes affecting phosphate-dosed drinking water within water and waste-water networks.

Author

Elizabeth Flint (ORCID 0000-0002-5781-2523)

With thanks to my supervisors Matthew Ascott, Daren Gooddy, Ben Surridge and Mason Stahl.

As a result of above average rainfall over the last six months, parts of the country are currently suffering from extensive flooding. This is primarily due to water in rivers, such the River Severn and River Wye, flowing out of their banks. The Environment Agency have issued a record number of river flood warnings and alerts, and these include warnings and alerts for groundwater flooding. The groundwater flood warnings and alerts cover parts of Dorset, Hampshire and Berkshire and are primarily on areas underlain by the Chalk aquifer.

Groundwater flooding typically occurs when groundwater rises up through the ground to meet the land surface. It can also result in flooded basements and the surcharging of sewers. Unlike flooding from rivers it may be slower to respond to rainfall, but once groundwater flooding occurs it may take many months to disperse. Due to the relatively wet winter, groundwater levels across much of the Chalk in southern England are already at above normal levels. As the soils are also currently fully saturated, should there be additional significant rainfall in the next month, there is the potential for more significant groundwater flooding in parts of southern England.

• 51ÁÔÆæ provides monthly summaries of the status of groundwater resources in the UK as part of the UK’s monthly
• publishes forecasts of future groundwater resources
• 51ÁÔÆæ also researches
• Practical advice from the Environment Agency to help
• Visit the Environment Agency for the very latest information on flooding
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