Changes in urbanisation and its effects on water quantity and quality from local to regional scale

Lead Research Organisation: NERC Centre for Ecology and Hydrology
Department Name: Rees

Abstract

Over the past 50 years changes in UK land-use have been considerable and substantial change is likely to continue. The UK population is projected to increase by 16% to 2035 which will bring about change to the size and structure of urban areas and increased pressure on land management, especially in the south-east. This project, by calling upon a range of tested modelling approaches and associated expertise will advance understanding of the fine-scale impacts of urbanisation on water resources and pollution, which are currently poorly understood. The focus will be on water security in the Thames river basin where projections of future population and climate indicate serious water stress. Detailed case studies at a local scale (including Bracknell and Swindon), where the impacts of past land-use changes on river hydrological and ecological regimes are likely to be large, will be undertaken and a novel integrated modelling approach developed and tested. The approach will then be rationalised and up-scaled for testing across the entire Thames, and, in conjunction with projections of urban development and land management change, used to quantify future effects. These findings will be set in the context of effects indicated to be a direct consequence of climate drivers.

Planned Impact

Outputs from the research are expected to bring benefits to stakeholders across multiple sectors as follows.

(i) Water managers: The results from the research will provide water managers, primarily the Environment Agency, Thames Water and the Rivers Trust, with a holistic assessment of the contribution of point source pollution from expanding population centres, and their relative importance compared to other pollution sources and climate change impacts. This information is important for defining strategies for reducing pollution and achieving good ecological status.

(ii) Local authorities: The growth of population centres is determined by planning decisions made at a local level. The output from the project will enable local governments and spatial planners to better understand the links between local growth strategies and the resulting impacts on the receiving waters, both locally and on the scale of the Thames basin. The research will also provide local authorities with information on the effectiveness of local water management strategies such as Sustainable Urban Drainage Systems.

(iii) Business community: This project is aimed at local planning so direct engagement will be with the local authorities. Most businesses will be interested indirectly and will get information through local authority channels. However we will use a number of existing knowledge exchange channels to engage with the wider business community.

(iv) Non-governmental organisations: The Thames River is used by a plethora of people and organisations for recreational (e.g. boating and fishing) and wildlife conservation. Examples include the Inland Water Association, Thames Anglers' Conservancy, and the Thames River Restoration Trust. All of these organisations have an interest in a reduction in pollution in the Thames River and the output of the research will assist these NGOs to use their limited resources where they are most likely to have a positive impact and as part of their educational material.

To best engage with a wide range of stakeholders we will put our findings in the context of provision of ecosystem services and how the sustainability of this provision may be affected by future change, both in urbanisation and as a result of climate. We will communicate project results to a topic group outlining the premise behind ecosystems services (that they represent the benefits in terms of monetary value that people receive from nature). The topic group will meet three times during the project and include representatives from organisations in all four sectors outlined above.

A proposed secondment of a CEH research scientist to work in Defra for a 20 day period, will not only allow policy makers to get involved in the interpretation of results but also to ensure our research outcomes directly inform their initiatives. Building on our existing collaborative links, research scientists will organise meetings in Parliamentary Office of Science and Technology to raise awareness of the research and gain feedback.

We have been successful in setting up a private sector partnership with the Earthwatch organisation who will contribute co-funding from a worldwide HSBC initiative. Manpower will also be provided by HSBC, in the form of "citizen scientists" who will be trained to participate in scientific data collection and thereby directly contribute to our project. Therefore, this will potentially be very influential, and with the help of Earthwatch, create very effective media for disseminating project findings in a wider context to a diverse range of beneficiaries. Sustaining the research and its influence beyond the lifetime of the project is important and we will probably seek to do this through a Knowledge Transfer Partnership with a business partner.

Publications

10 25 50
 
Description Existing model-derived estimates suggested warmer and drier summers expected by 2050 will trigger more frequent incidence of undesirable water quality: for example up to two weeks more per year when the River Thames has low dissolved oxygen, which currently only occurs very occasionally. The project pinpointed additional impacts of population growth on estimates of these and other water resources changes in the Thames. Measuring land cover, river flow and quality in urbanising case studies centred on Swindon and Bracknell improved our understanding of how urban areas affect water resources, which can better inform future developments.

The project revealed urban expansion is unlikely to continue progressing at recent rates with increased population largely being accommodated through densification. Consequently, hydrological changes due to climatic stressors are likely to swamp any signals of a more extreme flow regime resulting from urbanisation. Short-lived water quality problems downstream of urban areas resulted from flushing of accumulated sediment. This occurred following extreme weather conditions (e.g. flooding following dry periods in winter 2013-14). Chronic impacts resulting from wastewater overspills, though also apparent, were no more severe than summer low flow conditions when water quality is most vulnerable.

The research undertaken in the project attracted funds from a third party to undertake citizen science. In this venture, to date over 50 members of the public have been trained to take measurements using similar sensors to those used in the POLLCURB monitoring campaigns. In addition to the training accomplished the result of this initiative has been additional water quality dataset, new collaborations (a journal publication is being written with one of the citizen scientists) and general raising of awareness of river water quality issues.

In terms of methodological and model development:
1) a comparable set of land cover maps to enable land use change to be quantified in the Thames basin
2) A new hydrological model (URBMOD) was developed successfully to simulate river flows in urbanising catchments in the context of changes in climate
3) Simple meta-models of water quality (sediment, oxygen) have been developed for assessing responses to combinations of stressors
4) a model-based method for assessing the sensitivity of river water quality to different combinations of up to 5 types of stressor including urban growth
Exploitation Route The URBMOD hydrological model and the water quality sensitivity analysis framework can be used can be used by academics and policymakers. The models are of policy interest in that they can be used to assess combined impacts on water resources of urban growth and other changes in land use in the context of likely change in climate. There is also potential to use models for short term forecasts of water quality to give advanced warning of pollution incidents for example.
Sectors Environment

 
Description Joint Programme Initiative (JPI) Urban Europe/ NSFC - Sustainable and Liveable Cities and Urban Areas Call
Amount £935,483 (GBP)
Funding ID ES/T000244/1 
Organisation Economic and Social Research Council 
Sector Public
Country United Kingdom
Start 03/2019 
End 02/2022
 
Title Bracknell and Swindon hydrology and water quality 
Description Two years (2013-2015) of continuous water quality and river flow in urban rivers. Continuous water quality is measured at 3 locations: 2 in Swindon (River Ray) and 1 in Bracknell (The Cut). Continuous river flow is measured in 5 locations in Bracknell and 5 locations in Swindon. Locations are on the main rivers and on tributaries. Sub-hourly rainfall data has also been collected to determine spatial variability across the catchments. Additional continuous water quality was collected in 8 tributary locations (4 in Bracknell, 4 in Swindon) during the winter storms of 2013-14. 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact The data will be used to assess the influence of urbanisation on water resources 
 
Title Landcover change Thames 
Description A 10-class landcover spatial dataset in vector and raster (50m and 200m grid) format. The data are for snapshots in time between 1984 and 2015 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact The data will be used to assess impacts of urban growth on water resources 
 
Title URBMOD 
Description A lumped conceptual rainfall-runoff model specifically formulated for urbanised catchments in the River Thames basin. The model was developed by Thomas Kjeldsen and James Fidal at University of Bath 
Type Of Material Computer model/algorithm 
Provided To Others? No  
Impact The model will be used to assess impacts of future climate change and urban development on river flows. The model has the potential to be adapted for use in other environments, for example in regions of very different climate and urban morphology. This will yield scientific insights and be valuable for management and urban planning. 
 
Title Water quality meta-model 
Description Models were developed to estimate Dissolved Oxygen levels and Suspended Sediment fluxes in rivers draining urban catchments. The models were formulated based on analysis of sub-hourly data collected during POLLCURB. 
Type Of Material Data analysis technique 
Provided To Others? No  
Impact The models can be used to estimate the impacts of changing climate and urban growth on water quality. It is intended these models can be used in other sites where only daily river flow and climate information are available. 
 
Title Water quality model sensitvity analysis framework 
Description The purpose of the framework is to assess how combinations of multiple environmental stressors affect river water quality. The approach uses a process-based water quality model of a river network which has been adapted to run sequentially multiple times. This multiple-run component of the framework has been combined with a coded process which allows the various environmental stressors to be varied in magnitude systematically. A procedure for graphical analysis of output has also been incorporated in to the framework. The main steps are as follows: 1) gather and pre-process stressor data from modelled or monitoring sources 2) use code developed to create sets of input data files to cover all possible combinations of stressors for multiple applications of river quality model 3) apply set of bash scripts which enable model codes to run on cirrus cluster multiple times 4) post-processing of model output to assess points along a river network in context of target thresholds for good water quality 5) apply a procedure for graphical analysis and interpretation of stressor interactions 
Type Of Material Data handling & control 
Provided To Others? No  
Impact Sensitivity analysis of river eutrophication impacts has revealed that water quality responses to changes in multiple-stressor combinations is very sensitive to the choice of biological sub-model within the river quality model structure. The framework is potentially powerful in that it can be used for scenario analysis, which may involve incorporating data from other models used for policy and management support. For this reason it is of interest to government policy makers assessing how best to control unwanted effects of eutrophication. 
 
Description Collaborative workshop on river water quality modelling 
Organisation Tsinghua University China
Department Department of Hydraulic Engineering
Country China 
Sector Academic/University 
PI Contribution One week visit made by M Hutchins and O Hitt to the department comprising: Series of 4 seminars, Hands-on training sessions on use of QUESTOR river quality model. Meetings with academic staff.
Collaborator Contribution Students and staff gave seminars. Participation by 6 PhD students in training sessions. In collaboration with us 2 of the students are applying the model in case studies.
Impact We are making collaborative funding applications. The model applications will result in 2 journal publications. There will be exchange visits on an annual basis.
Start Year 2017
 
Description Convening a session at American Geophysical Union fall meeting San Francisco, 12-16 December 2016 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact M. Hutchins proposed a session for the AGU meeting. As response to request from organisers to merge sessions this proposal was linked with 4 others and a new session (ID: H11F and H13D) formulated entitled "New frontiers in water resources: achieving water resource security in times of climate change, urbanisation and agricultural expansion". At the conference it comprised a 2 hour oral block of presentation and a half day poster session. It was highlighted as a recommended session by the AGU organisers (see.URL below)
Year(s) Of Engagement Activity 2016
URL https://eos.org/editors-vox/navigating-the-2016-agu-fall-meeting-part-i#Hydrology
 
Description Lunchtime seminar at University of Bath 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact One hour lunchtime seminar on POLLCURB project given by M Hutchins
Year(s) Of Engagement Activity 2016
 
Description Presentation at a workshop on urban rainfall runoff modelling 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presentation by James Fidal at a joint workshop between Universities of Bath and Yonsei
Year(s) Of Engagement Activity 2016
 
Description Presentation on rainfall-runoff modelling in Seoul 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A presentation by James Fidal on "use of conceptual rainfall-runoff models in urban catchments" in Seoul (Oct 2015)
Year(s) Of Engagement Activity 2015
 
Description Seminars as part of Royal Holloway postgraduate case study 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Seminar held at CEH for postgraduate students and EA staff organised by M. Hutchins - included 1 hour presentation on POLLCURB project by M. Hutchins
Year(s) Of Engagement Activity 2013,2014,2015,2016
 
Description Summary of findings from two published papers investigating impacts of urban growth on water resources 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The blog by Mike Hutchins summarised findings from two papers one of which (Putro et al) is an official project publication. The purpose was to raise general awareness of these journal publications
Year(s) Of Engagement Activity 2016
URL http://www.ceh.ac.uk/news-and-media/blogs/urbanisation-has-impact-our-water-resources
 
Description Technical presentation to British Water 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact A presentation by Mike Hutchins on the POLLCURB project and the follow-on pathfinder WQF project to the British Water Innovation Focus group
Year(s) Of Engagement Activity 2015
 
Description Technical presentation to FWR Waste Water Forum 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A presentation by Mike Hutchins and Steven Loiselle covering the POLLCURB and follow-on pathfinder WQF projects. FWR are the Catchment Partners for the CABA in one of the key sub-basins in the Thames. Raising awareness and eliciting support from FWR is very important for the pathfinder
Year(s) Of Engagement Activity 2015
 
Description Technical presentation to FWR Waste Water Forum 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Presentation by M Hutchins on future water quality in the River Thames. The specific focus was on how future increases in water demand and climate pressures may affect water quality and what mitigation measures might be put in place. The presentation highlighted how changes in water management might benefit water quality and partly offset the future pressures.
Year(s) Of Engagement Activity 2018
 
Description Workshop with Thames Water 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact A professionally-facilitated workshop, organised by Mike Hutchins, to identify the views of the water industry on what benefits they might wish to gain from a water quality forecasting system in the River Thames. This formed part of the follow-on fund pathfinder WQF project
Year(s) Of Engagement Activity 2016