Catchment hydrology

Gauging station evaluation, relocation and design

We have significant expertise in designing and installing flow gauging stations, including modifications of existing gauging stations to facilitate fish passage (e.g. through retrofitting of baffles or adding a Larinier fish pass in compound with an existing gauging weir). We can advise on siting, choice of method/feasibility and design. We have also excellent working relationship with NIVUS GmbH, with whom we have worked closely in designing new transit time ultrasonic stations.

Strategic studies and network reviews

We have an impressive track record in relation to delivering strategic hydrometric studies:

From January 2007 to September 2010, we carried out an extensive national review of the hydrometric network in England and Wales on behalf of the Environment Agency. The work was undertaken in two phases: i) River Gauging Network, ii) Rainfall Gauging Network. As well as a comprehensive review of the existing network and assessment of requirements to meet future initiatives, software tools for and guidance on network management were developed.[1]
From September 2008 to June 2010 we carried out a strategic review of Hydro-Meteorological Monitoring networks operated by the Office of Public Works in Ireland. This involved the identification of the long-term strategic needs for flood-related hydrometric and meteorological data in Ireland, including strategic management requirements for effective data collection and provision of flood related information.
In 2012 we carried out a detailed review of the Hydrometric Network in Yorkshire and North East, whilst involved a review of drivers of the flow and level gauging network, quantification of benefits derived from the network and outline of possible network improvements, specification of gaps and redundancy in existing network and prioritisation for network improvements based on operational requirements.
In 2015 we delivered a detailed review of the hydrometric network operated by the Environmental Protection Agency in Ireland. This included a detailed comparison of the hydrometric network in Ireland with those in Scotland, Wales and New Zealand.
We are currently (2018) helping Waterways Ireland to undertake an evaluation of their monitoring network.

[1] See Davis, R., Zaidman, M., Grew, R. & Garrett, K. 2010. Evaluating the benefits of the hydrometric network in England and Wales. Proceedings of the British Hydrological Society Conference, Newcastle University, July 2010.

Hydrometric data validation and review

All the data we collect and supply undergoes strict validation and data assurance processes before use/issue. We are also able to undertake independent validation or checks of third party data; a recent example being an independent review of the quality of hydrometric data collected by the Tweed Forum as part of their Eddleston Water Project.

Our team has been widely involved in defining procedures for data management and assessment of data quality, of which some of the higher-profile projects have included:

Development of Operational Instruction outlining how the HiFlows-UK flood peak database should be managed, and implementation of improvement measures including rating updates and evaluation (Environment Agency, 2014).
Derivation of a classification scheme for gauging station data quality assessment (referred to as GSDQ) on behalf of the Environment Agency in 2002 and subsequent improvements, modifications and enhancements.
Reviews of the performance of the EA’s Tipping Bucket raingauge network, which included comparing accumulated rainfall from TBRs and their collocated storage raingauges and identifying reasons for any discrepancies in terms of calibration, site maintenance, under catch due to exposure, evaporation etc.
Development of a tipping bucket raingauge calibration procedure for the OPW.

Spot gauging service and rating curve development

We offer a spot gauging service using our own Valeport Model 801 Electromagnetic Open Channel Flow Meter, which we operate in accordance with BS EN ISO 748:2007 and which undergoes calibration every three years by the manufacturer. Recognising those situations where specialist equipment is needed we also have expertise with hired instrumentation including OTT’s QLiner, Sontek’s RiverSurveyor and FlowTracker devices and RD’s Stream Pro ADCP.

We have carried out flow gauging for Natural Resources Wales, Essex and Suffolk Water, National Trust and Irwell Rivers Trust, Aire Rivers Trust, South East Rivers Trust and the Environment Agency as well as private clients (e.g. in support of hydropower assessments, abstraction licence applications, internal drainage boards/water level management plans).

Our team is highly experienced in the development of new, and in the reviewing of existing Stage-Discharge and Velocity-Index ratings. We use our innovative in-house applications to aid hydrometric data review and analysis. To date we have derived over 100 new stage-discharge ratings on behalf of the Environment Agency. We also run training courses on the topic of extrapolation of high flow ratings and use of modelling to extend high flow rating limbs.

Training and support

We are expert trainers in hydrology (our team runs the foundation and advanced level training courses offered within the Environment Agency). We offer a range off-the-shelf courses covering theoretical and practical aspects of hydrological analysis but are equally able to provide tailored training based on real case studies and practical examples.

Visit our training page for more information and to book your place on a course today.

Drought and low flows assessment

Validation of historical data during drought periods and time series extension to cover historical droughts
Provision of expert advice on drought frequency analysis and modelling
Drought index calculation, regionally or on a site-specific basis
Low flow frequency analysis and interpretation
Accounting for future climate change impacts on the likely frequency and duration of low flow and drought events

Flow naturalisation and abstraction management

Estimation of natural flows by decomposition or other techniques; characterisation of the impact of artificial influences on catchment flow and the production of residual flow diagrams.
Conceptualisation of the impact of artificial influences for Catchment Abstraction Management Strategies (CAMS) and Water Framework Directive (WFD) assessments.
Detailed modelling for specific abstractions (river and groundwater).
Behavioural modelling of reservoir systems.

Flow estimation and analysis

Developing time series of flow at a suitable timestep using rainfall runoff models or mass balance methods to inform water resources, water quality and catchment flow studies.
Validation and verification of flow estimates using hydrometric and catchment information to give confidence that you are using the best information for your investigation.
Estimation of point flow statistics and flow duration curves using best practice methods and/or Low Flows software.

Our industry experience

Experience of preparing 12 Water Cycle Studies since 2013, including several combined Water Cycle Study and Strategic Flood Risk Assessments
Open and easy to do business with, with a strong focus on innovation and customer service
We use a team of expert technical leads to provide oversight of the assessments of water infrastructure, water resources and water quality modelling
National coverage from 20 offices in the UK and Ireland.

Improving the management of water

Whilst the primary responsibility for delivering water and wastewater services lies with the water companies, Local Planning Authorities can use the planning system to promote solutions which contribute to improving the management of water and provide other benefits, including:

Catchment Based Approaches and nutrient trading schemes to manage diffuse pollution
Sustainable Drainage Systems (SuDS) on new-builds and retrofit, including surface water disconnection for combined sewers to create capacity for development
Rainwater harvesting to reduce water demand in water-stressed areas.

Services we offer

Assess the present day and future capacity of the water resources, water supply, wastewater collection and treatment facilities
Identify how increase effluent discharges can be treated without causing detriment or preventing the receiving waster from achieving GES
identifying the responsibilities and timescales for implementing strategic infrastructure upgrades
Providing the evidence base for Local Plan policies on water efficiency, SuDS etc
Climate change analysis and adaptation.

Sustainability investigations

Investigation of impact of Habitats Directive and Water Framework sustainability reductions on water available for supply.
Aquator modelling to inform the impact of abstraction regimes on environmental indicators (e.g. lake water level, downstream river flow) and alternative water sources to support environmental impact assessments.
Assessment of the impact of sustainability reductions
Assessment and scenario modelling of water transfers (intra and intercompany).

Demand modelling and efficiency measures

Modelling of water demand under different scenarios including drought.
Quantification of the impact of drought measures on demand.

Drought planning and management

Development and review of drought triggers
Support for drought permit applications
Historic drought event characterisation
Drought frequency analysis and levels of service
Comparison of historic and extreme.

Climate change

Derivation of climate change inflow datasets for water resources models
Assessment of climate change impacts on available supply
Application of stochastic methods for climate change modelling.

Water resources modelling

Aquator model build and development
Application of Hysim, Mike BASIN, WRAPsim and iThink models
Deployable output assessment for water resource management plans
Investigating the deployable output benefits and utilisation of new sources.
Assessing impacts of flood risk management activity (for example flood drawdown proposals) on water available for supply.

Our team of experienced hydrologists can help you gain an understanding of catchment influences on river flows and levels at your site of interest.

How we can help you

Training and support

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