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Water environment, resilience and adaptation to change

Work Package 1.2 - Water resources and flood risk management

Research Deliverable 
1.2.3 Water environment resilience and adaption to change
Leading Ideas 
Climate and the Environment
Agriculture

Introduction

The role of resilience is particularly crucial in managing the impacts of environmental changes (i.e. climate change, land use change) for example to prioritise mitigation measures to tackle greatest risks first. Aquatic ecosystems can experience multiple and interacting pressures and respond suddenly to environmental change, sometimes flipping to a new equilibrium. However, our understanding of resilience to environmental change is limited due to the difficulty in detecting ecological stability across pressure gradients at various spatio-temporal scales. Lack of knowledge on how key ecosystem functions relate to multiple stressors and drivers of change (notably climate & land use) therefore constrains effective resilience-based responses. This has implications for meeting current policy targets and prioritisation of adaptation actions to avoid future loss of function and service. Furthermore, regulatory measures have often been implemented in isolation rather than maximising potential synergies for maintaining resilient functioning ecosystems.

The need to evaluate resilience at national-level thus defines a high-level requirement to assess present and future risk and adaptive capacity for catchments across Scotland.

Aim of Research

To evaluate the capacity of water resources to adapt to changing environmental and socio-economic conditions, in order to maintain key functions, goods and services (resilience) 

This RD addresses one of the fundamental research questions of the programme: How resilient are Scotland’s natural assets to climate change and other risks (invasive non-native species (INNS), pollution, etc.), and what are the key interventions to make them more resilient or to protect them from further harm? To do this, RD 1.2.3 considers components of natural and managed water systems (and their interactions), their responses to multiple stressors, aspects of risk vs resilience and control measures. Using case studies, we explore (a) the concept of multiple stressors acting on a water body now and under future scenarios; (b) the provision of goods and services through the water environment; (c) natural resilience of the water environment that we can characterise and utilise in managing change. This natural resilience may be utilised as an alternative or complement to conventional management approaches. We may also need to manage this resilience with engineering (e.g. flood defence; water treatment) and accompany it with actions to enhance community resilience.

The research in RD 1.2.3 focusses on:

  1. Catchment typologies of risk and resilience to enable better understanding of grouped behaviours in waterbody sensitivities and responses to multiple stressors and how we may combine catchment spatial data in meaningful ways related to functions.
  2. Wastewater effluents in terms of ecosystem resilience to effluents, sustainable treatments for trace contaminants, and novel circular systems for wastewater treatment.
  3. Drinking waters, for example tracing presence and sources of key pathogen risks to drinking waters.
  4. River temperature and its impacts for aquatic ecology.

Progress

2021 / 2022
2021 / 2022

To assess the risks associated with septic tank effluent discharges on water courses and the effect of persistent discharge to soakaway soils, septic tank discharge data was evaluated, and associated risks were formulated. The key factors that posed risks to water courses were the density of septic tanks in a given area, effluent concentration of phosphorus and other pollutants, the suitability of septic tank sites location and slope, soil properties, proximity of septic tank sites to watercourses and the absence of field drainage .  Soakaway soils were analysed for quality and phosphorus concentration compared to soils on the same sites that do not receive septic tank effluent. This work revealed that changes in soils receiving effluent occur such as pH and bioavailable phosphorus concentrations that correlate to the age of septic tank systems in operation.   Further work is needed to validate the findings.

Riverbed sediments were analysed for phosphorus release to stream water. Factors such as increase in atmospheric and water temperatures, alkaline condition and a decrease in dissolved oxygen enhance phosphorus release from sediments to water and thus the sediments are transformed from being a sink of phosphorus to a source releasing phosphorus to the water column.

Agricultural practices were assessed for Greenhouse Gas (GHG) production of which methane and nitrous oxide were considered major GHG with higher global warming potential than CO2 from soils, fertilizers, manure and grazing ruminant animals. Intensive agricultural practices, extensive use of fertilizers, dredging of farmland, overgrazing and land use changes contribute to GHG emissions.

Progress was made assessing novel and sustainable treatments to remove emerging contaminants from wastewaters and increase resilience in receiving waters. Previous work on developing novel sorbent material indicated that biochar was a promising adsorbent for removal of emerging contaminants.  Biochar derived from agricultural or industrial waste have advantages of low cost and availability. In collaboration with the UK Biochar centre (Edinburgh University), eight different biochars were tested for emerging contaminants adsorption from water. The result showed that the two sludge-derived biochars (SBC) were promising for pharmaceuticals removal, in particular, the SBC produced under 700℃ had the highest adsorption capability. Further experiments showed their efficient removal for both emerging contaminants (e.g. pharmaceuticals) and heavy metals (e.g. Cu). A wood-derived biochar was evaluated for its potential to remove DNA and antimicrobial resistance genes. Studies demonstrated a reduction in ARGs following filtration through biochar in artificial wastewater column experiments.

Highlights:

  • Soakaway soils that receive septic tank effluent discharge for the secondary treatment, exhibited changes in pH and phosphorus concentration compared to soils that do not receive effluent. The increase in soil acidity and the accumulation of the bioavailable form of phosphorus in soakaway soils appears to be related to the number of years that the septic system has been in operation and prolonged exposure to effluent can transform the soil from a sink to a source of phosphorus.
  • Long term monitoring in the Tarland catchment (north-east Scotland) has shown rising stream water phosphorus (P) concentrations over the last decade. An evaluation of the contributions to this decline in water quality from recycling of streambed P in sediment identified that influential sediment storage zones in low energy channels in the lower catchment provide P sources to stream water that contribute to decadal changes in water quality. This study shows a need for sediment management to maintain Water Framework Directive good ecological condition in streams and the value of such assessment methods to inform effective catchment management.
  • Sludge is the main by-product of municipal sewage treatment plant, which is rich in organic matter, making it a potential material for biochar production. The annual production of sludge has reached 5.48×107 t y-1 in the EU. The large production and secondary environmental pollution (e.g. landfill and incineration) means the resource utilization of sludge has attracted extensive attention. This study showed that the SBC exhibited promising efficiency for the contaminants (both emerging contaminants and heavy metals) removal, which suggested that this sustainable method can be potentially used for water treatment, in addition to realising resource utilization (sludge disposal). Biochars also showed potential to remove emerging biological contaminants such as antimicrobial resistance genes.
2020 / 2021
2020 / 2021

The impacts of nutrient enrichment of nitrogen (N) and phosphorus (P) to waters downstream from sewage discharge points were the focus of this work. Effluents from wastewater treatment plants that receive the mandatory secondary sewage treatment were evaluated and the effect of pollutants present in the effluent discharge to the receiving water was determined in five small rural river catchments. River response to effluent varied depending on hydrological regimes and was influenced by the high concentration of sewage discharge. Sewage effluent release has increased nutrient levels downstream from the discharge points, which caused increases in chlorophyll-a concentration and rate of growth. The influence of treated effluent discharge on riverbed sediments was observed in the increased sediment phosphorus content downstream. Thus, downstream sediments may have acted as a buffer to nutrient enrichment in the water column and may have given the water body resilience to effluent. This work is drafted in a scientific paper for publication.

Long term monitoring in the Tarland research catchment (50 km2 tributary of River Dee) has shown a rise in stream water phosphorus concentrations over the last decade. Contributions to this decline in water quality from recycling of streambed P in sediment was undertaken through studies of P spatial storage in the channel network, sediment and water compositions and P exchange dynamics (paper published in peered reviewed journal The Science of the Total Environment; https://www.sciencedirect.com/science/article/pii/S0048969721038626). Influential sediment storage zones in low energy channels (depositional zones predictable by GIS-based stream power assessments) in the lower catchment provide P sources to stream water that contribute to decadal signals in water quality. This shows a need for sediment management to maintain Water Framework Directive good ecological condition.

The effectiveness of riparian buffers in protecting the river network for maintaining sediment dynamics and physical and chemical conditions was investigated in the Tarland catchment through survey monitoring (land cover, soil quality, topography and water tables), and streams water quality monitoring data. This work has been extended to year 6 to combine the socio-economic and the biophysical data on the stream corridor, which includes the absence or presence of buffer strips, vegetation type, stream sediment parameters and water quality. This work will be drafted into a report to present to Scottish Government’s policy groups.

To evaluate the potential risk of emerging contaminants to catchments and removing pollutants such as pharmaceuticals and mixtures of compounds from aqueous solutions, fixed column experiments were investigated. The biosorbent tests showed that the biochar was one of most promising materials for emerging contaminants adsorption, therefore, further removal experiments were run in a fixed-column of biochar. This is to test the effect of column length, solution flow rate and the initial contaminant’s concentration as well as testing the different parameters of the solution such as organic matter and pH that could impact the column performance. In addition, the column-based experiments were investigated for the removal of compounds in single or combination, and the result suggested that biosorbent can potentially remove an individual compound as well as a mixture of compounds in solution.

 

Highlights:

  • Impact highlight:  Review of managing riparian buffer strips to optimise ecosystem services. Riparian buffer strips can provide numerous ecosystem services from pollution mitigation and provision of habitat for biodiversity to carbon storage and natural flood management. An open access paper explored how the placement, physical properties, management and vegetation structure influence the potential of riparian buffer strips to deliver a range of benefits. The review provided information for environmental managers, regulators and practitioners on how the multifunctionality of riparian buffer strips can be optimised through targeted management actions.  Catchment based approaches to managing riparian areas including through placement of multifunctional buffer strips, has the potential to help mitigate the effects of climate change.
  • Understanding riparian zones provides catchment benefits:  Collaborations between SEFARI researchers, Irish colleagues (Teagasc Institute) and Irish EPA funded research (Smarter BufferZ) led to a paper reviewing the use of spatial datasets to represent riparian functions such as canopy shade effects on the stream and flood inundation effects on the land. The work shows that knowledge of the spatial location of soils, topography, water flows and vegetation is critical in order to understand riparian condition and functions and to enable effective targeting of restoration of riparian zones.
  • Rivers response to effluent discharge is dependent on hydrological regimes and in some cases is influenced by the high concentration of sewage discharge. The receiving waters had increased nutrient levels downstream from the discharge points. For some river systems, riverbed sediments may have provided a buffer to the increased level of nutrients caused by effluent release to the water column giving the water body some resilience to effluent discharge. It is beneficial to continue monitoring river catchments associated with wastewater treatment plant discharge to better inform stakeholders and policymakers and to target the appropriate mitigation measures towards the most heavily polluted river catchment. 
  • Emerging contaminants work suggests that biochar was one of most promising materials for emerging contaminants adsorption, and therefore the focus is on biochar for further testing.
  • A study to examine the controls on dissolved reactive phosphorus (P) (the basis for WFD quality assessment) from sediments delivered to, and resident in, the channel network of the Tarland research catchment found spatially variable P release that was inversely related to specific stream power and increased in lower parts of the catchment (published paper available here).
2019 / 2020
2019 / 2020

Work continued to evaluate approaches to help inform the mitigation and assessment of physical (river temperature), chemical (nutrients, emerging contaminants) and biological (parasites) water quality issues in the face of changing environmental conditions. The research has led to developments in representing catchment pollution sources (geese, septic tanks and farmyards), now being shared with SEPA and informing developing applied work (via CREW) and collaborations with international water management scientists (Nordic Centre of Excellence BIOWATER (link is external). The Tarland long-term monitoring data and mechanistic studies, both RESAS-funded, continue to provide a strong basis for developing international collaborations with other researchers on the phenomena of rising background P concentrations in headwater catchments.

Work on assessing novel approaches to treating wastewater continued through two strands.  Firstly, the constructed wetland (CW) under two flow regimes was assessed. The focus was to refine the model based on existing data from Yr3 to help evaluate the performance of the CW. The work suggested that the current sampling regime requires further refinement for reliable estimation of bed efficiency.  Secondly, experiments continued with the application of sustainable biosorbent column for emerging contaminant removal from waters.  The results showed the column can potentially remove a single compound as well as a mixture.

Another aspect of this RD is assessing and modelling river temperature dynamics.  Models simulating daily river temperature from weather and river flow have been implemented for 41 catchments across Scotland to quantify past changes in river temperature and identify their drivers. For one catchment (River Gairn) where the James Hutton Institute monitors high-resolution data, deep learning models of hourly river temperature using weather covariates have been developed.

Highlights:

  • Two talks based on Scottish case studies were given to the Land Use and Water Quality conference (link is external) (Aarhus, June 2019) exploring (i) long-term changes in water quality variables and their relationship with changing river flow and (ii) reasons for differing response groups by combining spatial data into a model of phosphorus loading.
  • Demonstration of issues of internal phosphorus loading from river sediments interacting with management are pooling insights from long-term water quality monitoring, channel dynamics and condition, chemical P release processes. At the 9th International Phosphorus workshop (link is external) (Zurich, July 2019) research into sediment P release (internal P loading, a cause of rising river phosphorus concentrations which lead to water quality deterioration in a Scottish research catchment) was presented.
  • Collaboration strengthened with applied research in Ireland. SEFARI researchers presented multiple aspects of RESAS-funded research at the Catchment Science 2019 conference (link is external) (Wexford, November 2019), including modelling of phosphorus sources and mitigation; the F-MAPT tool to enable placement of Flooding Measures, riparian management and water payment for ecosystem services and soil erosion work. Researchers are working closely with the Teagasc Institute (link is external) and the Irish EPA (link is external) in riparian and Natural Flood Management (NFM) allied research projects with mutual benefit for land and water outcomes.
2018 / 2019
2018 / 2019

Catchment typologies of risk and resilience, which will help to quantify, group and predict different responses were investigated further, including the development and application of novel methods ranging from laboratory experiments to modelling approaches. We also continued monitoring of environmental variables at different field sites allowing robust analysis of the water environment, its resilience and adaptation to change (e.g. biomass growth and nutrient concentration in the constructed wetland at Dinnet and river temperature in the Gairn catchment).

The research conducted this year has resulted in a range of important findings in the individual projects. For example, risk factors to chemical and ecological responses in waterbodies have been identified (e.g. in terms of septic tank risk profiles in river catchments and by DNA extraction of protozoan parasites). Laboratory experiments have been conducted to quantify the removal of contaminants (such as pharmaceuticals and heavy metals) by biosorbents. In addition, analysis of monitoring data has been combined with water balance modelling to enhance process-understanding in the constructed wetland at Dinnet. Further, process-based and statistical modelling has been combined with trend analysis to explore long-term changes in river temperature and its drivers using a 105-year citizen science river temperature record of the river Spey. A model has also been developed to investigate the temporal pattern of high-resolution river temperature data at the outlet of the river Gairn.

Highlights:

2017 / 2018
2017 / 2018

Collectively, work in the RD has progressed ways of looking at risk vs resilience in the translation of pressures on the environment through risk factors to chemical and ecological responses in waterbodies. This has involved some conceptual strengthening via our cases studies, namely: river ecosystem susceptibility to diffuse and point source pollution; management of effluents in closed loop wastewater systems; temperature related stress to stream ecology; the factor of riparian condition in alleviating or adding to risk of impaired water quality. Two further case studies are in earlier development stages: improving pesticide and pharmaceutical data for rivers for risk evaluation; improving drinking water safety planning for the water industry to manage risk.

Highlights:

  • Evidence dissemination: A talk was given at the Rank Prize Funds meeting at Grasmere in Cumbria in the Symposium on “Soil Organisms and Pollutants and their Consequences for Human Health”, The talk addressed how to assess the human health risks associated with the use of reclaimed water for irrigation of amenity land and food crops.
  • Catchment typologies approaches underpin developing SRP and CREW work and international collaborations: Research between RD1.2.2, 1.2.3 and CEH conceptualises how landscape structure, soils etc. underpin how waters respond to environmental pressures. This framework is being used in the CREW project Eco-P 2 project, SRP phosphorus modelling, a recent paper on alleviating eutrophication, international links with BIOWATER project and a session at the EGU conference, Vienna. A report was delivered to stakeholders (SEPA, SNH, Forest Research, Scottish Water, Marine Scotland, SG), following a workshop in spring 2017, establishing the needs and development pathway of these concepts and applications.
  • Records from the past century show that Scottish rivers are warming: Research in RD1.2.3 combined citizen science, through archived long-term records of water temperature taken by fisheries and estates, with high resolution scientific data and developed statistical methods to provide evidence that Scottish rivers are warming. A factsheet outlines river temperature changes and recommendations to make rivers more resilient to potential future warming.
2016 / 2017
2016 / 2017

We have been developing approaches for typologies of catchments as a way of grouping behaviours with respect to ways that waterbody sensitivity factors translate catchment risks (pollution pressures etc.) into impacts. This has been widely validated with stakeholders. The pressures and responses have been selected to serve the wider work and comprise: eutrophication impacts, temperature impacts on aquatic ecology and drinking water quality. As part of this, key datasets have been attained working alongside SEPA, for point sources, livestock number and sensitivity factors like riparian structure. New evidence provision has involved a package of work on effluents, septic tanks and larger wastewater sources, environmental tracing of effluents and novel control measures for effluents (working with Scottish Water) and river temperature effects.

Highlights:

  • New experiments started at the the constructed wetland at Dinnet. For this purpose, the existing vegetation has been harvested and locally available gravel has been chosen as standard material in the beds. It was decided to trial novel "add on" media in additional modules discrete from the main beds.
  • Structures to represent risk vs resilience in catchment systems are being developed within RD1.2.3 with links to developing risk modelling (for phosphorus) in RD1.2.2 and using expertise from CEH supporting waterbody ecological impacts. A Catchment Typologies of Risk and Resilience report has been delivered to stakeholders (SEPA, SNH, Forest Research, Scottish water, Marine Scotland, SG) who supported a workshop in spring 2017, establishing the needs and pathway of development.
  • WP staff met with representatives of the drinking water industry and regulators (Scottish Water, the Drinking Water Quality Regulator for Scotland, and SEPA) and agreed a pathway to integrate research on understanding, communicating and tackling risks to drinking water supply.

Future Activities

New research will assess river corridor climate resilience functions, including mitigation (C storage/exchanges) and adaptation (societal river corridor usage and management) as part of uniting riparian buffer management plans (RBMP) with climate and biodiversity policies. This involves a ‘macro river buffer viewpoint’ at landscape to national levels and their role in land-water planning. The research links soil – water indicators and processes and scales at plot (water table variability, C storage) to catchment (riparian controls on exports of water, nutrients, sediment, dissolved and particulate C forms), to national application. This work has three research objectives: defining the extent and attributes of river corridors at Scotland scale (obj 1); understanding how pressures influence river corridor functions (obj 2); evaluating examples of corridor restoration (obj. 3).

Future work would aim to develop and apply the sustainable method (e.g. sludge derived biochar) for emerging contaminants from real environmental waters (e.g. wastewater effluent), to achieve both the resource utilisation and wastewater treatment. Future modelling will consider mitigations for AMR and biochar in the new RESAS D2.

Selected Outputs

2016/17

2017/18

2018/19

2019/20

2020/21

2021/22