Complex hydrological controls on wet dune slacks: The importance of local variability

Jones, Melanie; Reynolds, B.; Brittain, S. A.; Norris, Dave; Rhind, Peter Martin; Jones, R. E.

doi:10.1016/j.scitotenv.2006.08.040

Cited by 27 publications

(18 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The majority of the slacks dry out in summer with the water table falling to around 50 cm below ground level and only 10% of the slacks remain flooded throughout an average year. These dynamic conditions provide environments for rich assemblages of flora (Jones et al 2006;JNCC 2007) and breeding grounds for rare amphibians such as the Natterjack Toad Epidalea calamita (Sefton Coast Partnership 2007).…”

Section: Study Sitementioning

confidence: 99%

Predicted effects of climate change, vegetation and tree cover on dune slack habitats at Ainsdale on the Sefton Coast, UK

Clarke

Ayutthaya

2009

J Coast Conserv

View full text Add to dashboard Cite

Dune slack habitats are highly dependent on the availability of water to support flora and fauna. Typically this is provided by shallow groundwater. This paper describes the seasonal and long term variation in groundwater levels in part of the Sefton coastline between 1972 and 2007. The effects of climate change, vegetation management and coastline realignment on groundwater levels are modelled. The observed annual water table levels rise and fall with an amplitude of 1.5 m, but longer term variations and trends are apparent. A stochastic water balance model was used to describe the changes in water table levels in slack floors in the open dunes and also in areas afforested with pine trees. It was found that the pine trees evaporated 214 mm/year more than open dunes vegetation, resulting in the water table being 0.5-1.0 m lower under the trees than under the open dunes. The effects of climate change on the ground water was simulated using predictions of future climate conditions based on the UKCIP02 medium high emissions scenario. The increase in temperature and change in rainfall patterns will result in a decrease in mean ground water levels by 1.0-1.5 mm in the next 90 years. Typical patterns consist of sequences of 5-10 years of low water table levels interspersed by infrequent sequences consisting of 2-5 years of relatively high or "normal" levels. These results indicate that that flora and fauna that cannot survive a 5-10 year period of water table levels >2.5 m below ground level are unlikely to survive or persist in many slack areas and a change in the ecology of these slack may become inevitable. Other effects of climate change include sea level rise which will result in a gradual rise in water table levels. Coastal erosion will increase the water table gradient to the sea and result in a slight lowering of the ground water levels. Conversely coastal accretion will reverse this process. The spatial distribution of coastal erosion and accretion along the Sefton coastline and its likely impacts on groundwater levels are discussed. The modelling work described in this paper has identified the factors which have the largest effect on groundwater levels in temperate coastal dune systems.

show abstract

Section: Study Sitementioning

confidence: 99%

Predicted effects of climate change, vegetation and tree cover on dune slack habitats at Ainsdale on the Sefton Coast, UK

Clarke

Ayutthaya

2009

J Coast Conserv

View full text Add to dashboard Cite

show abstract

“…The water table in the slacks is near the surface, or intercepts it during periods of high water levels, but has a high seasonal variation' (Grootjans et al 1998). Groundwater response to recharge is different in different slack types (Lammerts et al 2001) and lags between rainfall and groundwater level change in some systems can be 4-7 months (Jones et al 2006). Groundwater table variations determine the abundance of many slack species, in particular in wet (humid) slacks (Willis et al 1959a;Willis et al 1959b).…”

Section: Dune System Ecologymentioning

confidence: 99%

Modelling small groundwater systems: experiences from the Braunton Burrows and Ainsdale coastal dune systems, UK

et al. 2017

View full text Add to dashboard Cite

Coastal dunes are delicate systems that are under threat from a variety of human and natural influences. Groundwater modelling can provide a better understanding of how these systems operate and can be a useful tool towards the effective management of a coastal dune system, e.g. by identifying strategically important locations for flora and fauna and guiding the planning of management operations through predicting impacts from climatic change, sea level rise and land use management. Most dune systems are small, typically of the size 10-100 km 2 , compared with inland groundwater systems. Applying conventional groundwater modelling approaches to these small systems presents a number of challenges due to the local scale of the system and the fact that the system boundaries (sea, drains, ponds etc.) are close to the main body of the aquifer. In this paper, two case studies will be presented using different modelling approaches to understand the groundwater balance in two dune systems in the UK. The studies demonstrate that, although conventional hydraulic models can describe the general system behaviour, a fuller understanding of the recharge mechanisms and system boundaries is needed to represent adequately system dynamics of small groundwater systems.

show abstract

“…Hydrochemical analysis has been undertaken at Merthyr Mawr between 1998 and 2015 (Jones et al 2005;Jones et al 2006;Water Management Consultants 2008;Schlumberger Water Services 2010). Samples have been collected from dipwells and boreholes but primarily from the Burrows Well, the ephemeral spring that feeds the large slack.…”

Section: Groundwater Nitrate Loadingmentioning

confidence: 99%

Merthyr Mawr: a case study for the assessment of nitrate at humid dunes in England and Wales

et al. 2017

View full text Add to dashboard Cite

Humid dunes in the UK are at risk from nutrient pressures from multiple sources. The Water Framework Directive 2000/60/EC (WFD) requires assessment and identification of these pressures with appropriate measures defined to mitigate against further damage. We discuss the application of nitrate threshold values for the WFD classification, illustrating this with a case study at Merthyr Mawr, South Wales, where ephemeral groundwater discharge from a spring ('Burrows Well') sourced within the Carboniferous Limestone, creates a large dune slack. Ecological surveys suggest that the vegetation in this slack was in unfavorable condition, due to high levels of nitrate. Applying the source-pathway-receptor model an investigation was undertaken to improve the conceptual model and assess the significance of damage from groundwater derived nutrients. Results show groundwater nitrate ~ 10mg/l as N feeding the main slack waters. The vegetation survey data shows clear evidence of ecological damage, and the hydrogeological data traces the source of this back to the Carboniferous Limestone aquifer and not the overlying blown sands. Discharging groundwater is the source of the enrichment. Isotopic analysis shows that the N is derived from inorganic fertiliser and atmospheric N. During the first cycle WFD characterisation the unfavorable status of the dunes due to chemical groundwater pressure resulted in a failure of the surrounding groundwater body, which was designated as poor status. The site has been re assessed for the 2nd Cycle WFD characterisation where recently developed nitrate 'threshold' values have been applied to assess the significance of damage for groundwater derived nutrients. The surrounding Carboniferous Limestone catchment is complex and could not be sufficiently constrained, thus land management changes could not be targeted. The paucity of historical or repeat vegetation surveys limits our ability to measure change within the dune vegetation and causes difficulties in understanding the impact of multiple pressures.

show abstract

Complex hydrological controls on wet dune slacks: The importance of local variability

Cited by 27 publications

References 21 publications

Predicted effects of climate change, vegetation and tree cover on dune slack habitats at Ainsdale on the Sefton Coast, UK

Predicted effects of climate change, vegetation and tree cover on dune slack habitats at Ainsdale on the Sefton Coast, UK

Modelling small groundwater systems: experiences from the Braunton Burrows and Ainsdale coastal dune systems, UK

Merthyr Mawr: a case study for the assessment of nitrate at humid dunes in England and Wales

Contact Info

Product

Resources

About