Novel tools for quantifying and managing sediment and nutrient loss from agricultural land

This research project has arisen in relation to the EU's legislation of the Water Framework Directive established due to the global issue of soil erosion and nutrient loss threatening the water quality through pollution and eutrophication. The WFD involves achieving targets of all waterbodies possessing 'good ecological status' by 2027, alongside determining which variables constrain or maintain this. These variables are often site-specific, relating to geomorphology, climate and land-use.

In Northern Ireland over half of all waterbodies fail to achieve the 'good' ecological status. Research has indicated that sources of diffuse agricultural pollution, typically from phosphorus and nitrates applied through chemical fertilisers and slurry, are the main source of waterbody nutrient enrichment and eutrophication. Northern Ireland has issues regarding excessive post-war application of fertilisers, coinciding with agricultural intensification, leading to excessive legacy levels of nitrogen and phosphorus present in soils. Recent research on catchment management has shown that observational techniques are either too site-specific or coarse to appreciate the variables contributing to waterway degradation. There is a requirement to develop catchment-based studies to understand the scale, frequency and magnitude of sediment
utrient loss.

This project aims to develop a multi-method approach to evaluate and monitor nutrient and sediment loss from agricultural land.
The objectives of this study include;

1. Undertaking fieldwork to investigate the sources and losses of sediments and nutrients, alongside collecting water samples to investigate water quality with analysis on phytobenthic, macroinvertebrate and plant communities.
2. Using remote-sensed data from satellites and drone equipment in the construction of digital elevation models for usage in modelling simulations to understand mechanisms of sediment and nutrient losses. This data will also be used to model conservation methods to derive a set of recommendations to improve water quality.
3. Apply multispectral imagery and fieldwork-based evidence to quantify, map and assess nutrient and sediment loss zones across the studied catchments.
4. Run catchment-scale soil erosion models to simulate runoff and soil loss changes under present-day climate, future climate change, land use and management scenarios in order to design appropriate mitigation strategies.
Northern Ireland fieldwork focuses upon three catchment sites of the Blackwater, Upper Bann and Colebrooke.

Year One: Investigating the sources and losses of sediment and nutrients in catchments. Quantifying pathways and movement, assessing levels of damage to both land and water bodies. Usage of fieldwork (alongside remote sensing e.g. drones and LiDAR data) and laboratory analysis techniques to establish parameters of losses and water quality status.

Year Two: Management strategies instigated at sites to deal with issues of sediment/nutrient loss and water pollution. Field visits to Scotland concerning catchments where management techniques have been introduced and a showing wider context of water pollution and sediment/nutrient loss beyond Northern Ireland.

Year Three: Monitoring improvements on catchments following the implementation of management strategies, repetition of original fieldwork/laboratory analysis to establish if benefits to water quality and a reduction in sediment/nutrient losses.

The techniques and observational skills/approach developed in this project will be applicable across many catchment areas and is not purely specific to Northern Ireland in its theoretical framework and as such the project may drive new areas of research. The project recommendations in terms of water quality improvement and sediment loss mitigation could be applied to the study catchments to drive current directives and indicate new preferential management techniques to achieve the WFD target by 2027.