Dr Sim M. Reaney

Dr Sim M. Reaney

Associate Professor in Catchment Hydrology

Talks and presentations

Modelling and using structural and functional connectivity

March 01, 2018

Talk, University of Palermo, Palermo, Italy

The understanding of hydrological connectivity is often broken down into two distinct types: functional and structural (see Bracken et al 2013). Functional connectivity refers to the dynamic feedbacks that occur within the short timescale of storm events, such as surface flow dynamics and erosion – deposition of the soil surface. Structural connectivity refers to the controls that the fixed characteristics of the environment, for example, landscape topography and vegetation pattern, have on the strength of the connectivity over long time scales. This paper presents how both functional and structural connectivity can be modelled and examples of how the structural connectivity approach has been used as a key dataset within a spatial decision support system.

Spatio-temporal dynamics in phytobenthos structural properties reveal insights into agricultural catchment dynamics and nutrient fluxes

December 01, 2016

Talk, In the proceedings of AGU Fall Meeting Abstracts, San Francisco, USA

Low order streams are spatially extensive, temporally dynamic, systems within the agricultural landscape. This dynamism extends to the aquatic communities within these streams, including the phytobentos, which demonstrates considerable resilience to diffuse anthropogenic nutrient pressures and changing climate dynamics. The phytobenthos community can substantially contribute to the food web, in particular diatoms, which dominate photo-autotrophic assemblages in low order streams. Diatoms are widely used in ecological monitoring because of their high sensitivity to environmental condition, but knowledge is limited on the ecological effects of winter disturbances and variance introduced by multiple and interacting pressures (N, P, sediment), introducing bias in understanding temporal dynamics in benthic diatom communities. Using the environmental time series data from long term monitoring within the River Eden Demonstration Test Catchment programme, we assess the impact of multiple hydro-chemical stressors on phytobenthic community resilience, and synthesize the impact of an extreme winter event. Monthly data from diatom communities collected in the Eden DTC from March 2011 to present show that river flow, strongly coupled to precipitation, is a key driver of these communities. Discharge has a direct effect on communities through scouring, but is also tightly correlated to nutrient delivery, such that 80% of the annual TP load arrives in 10% of the time. Trophic Diatom Index (TDI) values demonstrated considerable resilience by the stability of inter-monthly TDI scores over 5 seasonal cycles against the characterised highly variable hydrological regime. This research demonstrates that well characterised winter disturbances are critical to understanding drivers of aquatic dynamics. This has implications for catchment diffuse pollution policy, farm management and economics, given the climate projections of increases in frequency and intensity of extreme winter events, which may alter instream nutrient fluxes.

The River EdenDTC Project: A National Demonstration Test Catchment

April 01, 2012

Talk, In the proceedings of EGU General Assembly Conference Abstracts, San Francisco, USA

Our environment is a complex system of interactions between natural process and anthropogenic activities that disrupt them. It is crucial to manage the balance for continued food production whilst maintaining the quality of the environment. The challenges we face include managing the impact of agricultural land use on aquatic quality and biodiversity as an integral system, rather than as separate issues. In order to do this, it is critical to understand how the different components are linked - how does land use affect our water courses and ground water, and their associated ecosystems, and how can the impact of agricultural land use on these systems be minimised? Regulating farm nutrient management through measures that minimise sources, their exposure to mobilisation, and reduce drainage pathways to water courses are all fundamental to the UK’s approach to meeting the Water Framework Directive objective of achieving ‘good ecological status’ in all surface and groundwater bodies by 2015. The EdenDTC project is part of a 5-year national Demonstration Test Catchments (DTC) environmental scheme, aiming to understand the above issues through combining scientific research with local knowledge and experience from multiple stakeholders. The DTC project is a 5-year initiative by Defra, Welsh Assembly Government and the Environment Agency, which encompasses a research platform covering three distinct river catchments: the Eden in Cumbria; the Wensum in Norfolk; and the Avon in Hampshire. Within the EdenDTC, the impact and effects of multiple diffuse pollutants on ecosystems and sustainable food production are being studied on a river catchment scale. Three 10 km2 focus catchments, selected to represent the different farming practices and geologies observed across the Eden, have been instrumented to record the dynamics of agricultural diffuse pollution at multiple scales. Within each focus catchment, two sub-catchments were selected: one control and one mitigation, in which a number of existing and novel mitigation measures will be tested. A number of on-farm measures, aimed at reducing agricultural diffuse pollution, will be evaluated by monitoring their effect on water quality and associated biodiversity. In order to achieve this, state of the art hydro-meteorological logging systems have been installed. The outlets of the focus catchments each have a ‘high-tech’ multi-parameter station that will provide data for total P, soluble reactive P, nitrate, ammonium, temperature, conductivity, dissolved oxygen, turbidity, pH and flow. At the sub-catchment scale are 10 sub-stations, which provide a record of turbidity and water level. All are continuously sampling at 15 minute intervals and are telemetered. The goal is to give an abundance of high quality, multi-scale continuous data provided in real time. Additional storm sampling is being performed at all stations using automatic water samplers, and monthly spot samples are also analysed for each site. The information gathered at these different scales is hoped to improve the effectiveness/efficiency of schemes such as the England Catchment Sensitive Farming Delivery Initiative (ECSFDI). It is also hoped that many of the mitigation features will be multipurpose, having positive effects on flooding, carbon sequestration, habitat creation and biodiversity.

Understanding nutrient connectivity at the landscape scale: The use of the SCIMAP approach in the UK and Ireland

December 01, 2011

Talk, In the proceedings of AGU Fall Meeting Abstracts, San Francisco, USA

Many approaches to understanding diffuse pollution risk at the landscape scale have focused on its ‘sources’ and ‘mobilisation’ with a basic representation of the effect of connectivity between the landscape the receiving waters. Connectivity will determine whether source areas become critical source areas and create problems in the receiving waters. It is the landscape position of a source, both in terms of its upslope contributing area and its downslope flow path, that determine the likelihood of a connection being made. The SCIMAP approach, developed at Durham and Lancaster Universities with the Environment Agency, has taken a strongly connectivity driven approach, set within a risk based framework. SCIMAP aims to predict the location in the catchment that is most likely to be the source of an in stream water quality problem derived from diffuse pollution. The predictions are generated at a 5m-pixel level, to give within field estimates of risk and connectivity, and applied to whole landscapes (from 1 to 2000 km2 +) to give a broad overview of the issues. Recent work has shown that there is significant value in adding a detailed connectivity treatment when predicting measured patterns of water quality. The SCIMAP approach to diffuse pollution risk mapping has been applied by: the Environment Agency under the Catchment Sensitive Farming program; the Teagasc ‘Agricultural Catchments’ program; the Defra funded ‘River Eden Demonstration Test Catchment’; and various river and wildlife trusts in the UK. This poster shows an overview of the SCIMAP approach and the results from both the Teagasc ‘Agricultural Catchments’ and the EdenDTC projects.