2022 – Coastal Aquifers
The IAH-GB, together with the Hydrogeology group of the Geological Society London hosted the 2022 Ineson Lecture. The theme was Coastal Aquifers.
In recognition of his extensive research and publications in this area Professor Jimmy Jiao of Hong Kong University was invited be the keynote speaker.
Coastal hydrogeology has become one of the most important frontier topic areas in groundwater science. This frontier has become particularly important because most of the world’s population now lives within 100 km of coastlines.
The programme for the day (including speaker abstracts and biographies) can be downloaded here.
Speaker abstracts:
Clive Carpenter (GWP.UK); Small Island Hydrogeology – An introduction to some of the practical realities of working as a hydrogeologist in remote island states, in data sparce environments with limited technical resources. Using case studies from the atoll states of the Maldives and Kiribati, karstic island of Niue, and volcanic terrain of Samoa, examples of different groundwater investigation and exploitation techniques and their application to decision making for sustainable development, land use planning, drought resilience and climate adaptation are discussed.
Jean-Christophe Comte (University of Aberdeen; Freshwater-saltwater relationships and sustainable management of groundwater resources in coastal aquifer systems. Coastal populations, which make around 40 % of the global population, directly or indirect rely on freshwater from coastal aquifers and exhibit some of the highest growth rate globally, most particularly in developing countries. By the end of the century, it is projected that the vast majority of the world’s megacities will be coastal. Fresh groundwater resources in coastal regions are challenging to manage because aquifers are often very productive but vulnerable to salinisation, including seawater intrusion. The spatial and temporal dynamics of saltwater intrusion itself is complex in coastal areas because driven by multiple factors that are heterogeneous in space and changing over various timescales. This includes variable degrees of geological heterogeneity, preferential flow pathways, complex salt evapo-concentration patterns caused by non-uniform evaporative and plant water uptake processes in low-lying and island settings, high-rate point abstractions, short-term variability and long-term trends in recharge, tidal processes, and long-term sea-level rise. In this context, decision-support for management and planning of coastal groundwater resources requires robust monitoring and modelling tools with high-resolution, both spatially and temporally, adapted to the specific hydrogeological setting. The presentation will give snapshots of a range of coastal and island aquifer settings around the world providing an overview of the typical spatial and temporal patterns of the freshwater-saltwater interface and the key drivers that control them, as resolved from a combination of advanced hydrological, geophysical and groundwater modelling approaches. It will further expand to the implications this has in terms of local-to-regional coastal groundwater resources management and sustainability, illustrated through case studies in East Africa.
Professor Adrian Butler (Imperial College London); Developments in monitoring and modelling saline intrusion in coastal aquifers – Saline intrusion is a global problem potentially affecting millions of people who live on or close to the sea. It occurs when freshwater aquifers are hydraulically connected to estuaries and coastal waters. Due to its excess density, seawater can enter a coastal aquifer. This results in an interface between the discharging fresh water and intruding saline water. This interface can respond both to changes in recharge and to abstractions from coastal wells. If over-exploited, coastal groundwater sources can become compromised by the ingress of saline water. Using work from the south coast of England and the north coast of Northern Ireland, the presentation will show how measuring self-potential (SP) in boreholes, combined with other conventional monitoring methods, can used to remotely detect changes in the saline-freshwater interface. It will also demonstrate new developments in IC-FERST, a powerful subsurface reservoir and groundwater modelling package, to simulate these changes. Together, these are providing new tools and techniques for groundwater managers in coastal areas.
Harriet Carlyle (Sweco); A history of saline intrusion investigations in the Chalk of Yorkshire; The East Yorkshire Chalk is an aquifer of strategic importance for public and private groundwater supply to the city of Hull and other urban centres in the region. Saline intrusion from the Humber Estuary due to over-abstraction in Hull began during the industrial revolution but despite various studies over the years, it is not clear whether this is still occurring or whether it is a legacy issue. This presentation reviews previous studies that have been undertaken and discusses on-going investigations that aim to understand whether salinity is still increasing in the Hull area. If it is, then the investigations will focus on whether the existing public water supply abstraction regime is playing a part in the increasing salinity either through continued saline intrusion from the estuary or migration of saline connate water, or whether other sources of salinity such as application of fertilisers or road salt spreading are contributing to the problem.
Rik Ingram (WSP) Finding the balance: a tale of saline intrusion and groundwater flooding on the Lincolnshire coast – Groundwater is a valuable resource in eastern England, where rainfall rates are low and there are few large rivers. In Grimsby, at town on the north-east Lincolnshire coast, groundwater has been abstracted from the Chalk aquifer for public water supply and industrial use since the mid-19th Century. Rapid industrialisation and population growth resulted in over extraction of groundwater and many abstractors were affected by saline intrusion in the mid-late 20th Century. Since that time, groundwater abstraction rates have fallen, partly due to the changing economic climate and partly due to proactive management of groundwater abstraction by abstractors and regulators. Groundwater levels have started to rise as a result and groundwater flooding is becoming more prevalent. Groundwater management in the catchment around the town is now focussed on finding a balance to protect property and infrastructure from flooding whilst minimising saline intrusion risk. We will present the hydrogeological story of Grimsby and discuss the opportunities that are being explored to make best use of the local groundwater resource. We hope this will serve as both a cautionary tale and optimistic case study for groundwater management in other coastal towns and cities.
Geraint Burrows (Groundwater Relief); Solidarités International (SI), in collaboration with the Ministry of Water & Environment (MoWE), is implementing a 3-year project to increase water availability within 4 districts on the West Coast of Yemen. Groundwater Relief has supported this work through undertaking a groundwater investigation of the coastal aquifers in the region and through establishing a groundwater monitoring network in collaboration with National Water Resource Authority staff. Historic and recent water quality data has shown impacts of saline intrusion on key coastal towns water sources. A 3D geological and water quality model developed as part of the assessment indicates that there are potentially significant fresh water resources within the Tihama Coastal Plain that could be used to support coastal town water supplies.
Professor Jimmy Jiao (University of Hong Kong; ) Coastal hydrogeology – Coastal hydrogeology has become one of the most important frontier topic areas in groundwater science. This frontier has become particularly important because most of the world’s population now lives within 100 km of coastlines. Coastal groundwater problems involve highly dynamic physical, chemical, and biological interactions between seawater and groundwater. The expanding human presence in coastal areas has dramatically changed the coastal natural environment and created some environmental, ecological, and engineering problems, but at the same time also offered unprecedented opportunities for novel research. This lecture will cover some relatively new topics that have emerged in the coastal hydrogeology, including modification of groundwater regime by human activities such as land reclamation and deep foundations, tide-induced airflow and its impact on the stability of coastal structures, submarine groundwater discharge and its contribution to red tides and ocean acidification, and palaeo-hydrogeology and its implication on offshore groundwater reserves.
