Hydro GIS Ltd

Established in September 2004, Hydro-GIS Ltd. is a specialist consultancy company offering expert and independent service in the field of hydrology, water resources and geographical information systems (GIS).

Areas of expertise include :
river picture

Hydro-GIS Ltd is an Environment Agency framework consultant

flooding in bensonIs Your Business/Organisation at Risk of Flooding?
Flooding from rivers, the sea, surface water or groundwater is the natural hazard which has the greatest impact on the UK 
Are you aware of the risk of flooding at your business as shown by Environment Agency flood zone maps?
Remember during times of flooding the emergency services will be fully stretched and will prioritise areas where lives are at risk. They may not be able to assist in protecting your business premises.
Do you have designated staff members or volunteers who are able to undertake emergency measures in the event of a flood occurring and be able to also act outside of the normal business hours?
The impact of flooding may not be the actual inundation of your premises but other effects from further afield.
You should consider whether the following scenarios are likely to have an impact:
Flooded roads and railways preventing staff from reaching your business;  or preventing you from reaching your customers or them you; or preventing essential goods from being delivered
If flooding has affected power, water supply and wastewater in your area are you still able to function as a business?
A Flood Management Plan will help reduce the impact on your business.

pictureHydro-GIS staff have over 50 years experience in hydrology and water resources, and have worked for national and international governmental organisations, research institutes, academia and the private water and environment sector. We have established a network of associated consultants(please see the useful links page).

Dr Harvey Rodda PhD MCIWEM, is a director of Hydro-GIS Ltd with over 15 years postgraduate experience in research and consultancy in the public and private sectors in the UK and overseas. He graduated in Environmental Science from Lancaster University and completed his PhD in the Department of Geography, Exeter University in 1993. While working at NIWA in New Zealand from 1994-98, Harvey developed hydrology and water quality models and pioneered the application of GIS for hydrological modelling in New Zealand. Back in the UK, he worked on the development of a UK flood risk model for use in the insurance sector. As a principal hydrologist for a firm of consulting engineers, he led a number of flood related projects including Section 105 flood risk mapping for the Environment Agency, the development of flood risk models for the Czech and Slovak Republics, flood risk assessments, and specialist hydrology and water quality modelling studies.

Professor John Rodda DSc, FRMet Soc, FRGS, MCIWEM, is an Associate Director of Hydro-GIS Ltd. He was previously director of the Hydrology and Water Resources Department of the World Meteorological Organization in Geneva for 8 years, from 1988-1995. He has worked in both the research and water arms of central government and in research at the former Institute of Hydrology where he was Assistant Director. As well as being President of the International Association of Hydrological Sciences from 1995 to 2001, he has been a consultant to the UN World Water Assessment programme, to UNESCO, the European Union, DFID, and NERC, mainly in the fields of world water resources, water governance and the appraisal of programmes. He published some 80 scientific papers and 6 books concerned with Hydrology and water resources, 2 being translated into Russian.

Dr Rose Wood PhD, is a Principal Oceanographer at Hydro-GIS Ltd. She graduated in Mathematics from Cambridge University and was awarded a PhD from Exeter University for her thesis on waves. After some time in computer simulations, Rose worked on coupled ice-ocean models at the McGill University in Montreal, Canada before joining Plymouth Marine Laboratory as an oceanographic modeller. For Hydro-GIS she is developing coastal flood models, undertaking historical flood research and related numerical data analysis.

Sabine Rodda MSc, is a director of Hydro-GIS Ltd. With a degree in business studies and an MSc in Physical Geography (Freiburg University, Germany), Sabine's responsibilities include business development, marketing and web development

Flood Catastrophe Modelling

A major component of the consultancy work undertaken by Hydro-GIS Ltd over the past six years has been the development of flood catastrophe models for the re-insurance sector. These models are used as pricing tools for brokering contracts between re-insurance and insurance companies and are based n the following components:
  • A detailed understanding of the hydrology of the study area including the characteristics of flooding and historical flood events;
  • The analysis of high quality hydrological data or obtained from published sources and state hydrological services;
  • A large number of synthetic flood events with a specific return period for each event;
  • Explicit modelling of the effect of flood defences using a probabilistic breaching routine;
  • Flood depth and extent maps produced using 2-dimensional cell based modelling with GIS.
Since 2004 Hydro-GIS Ltd has developed regional river flood catastrophe models for Central and Eastern Europe, including the countries of Austria, Hungary, Czech Republic Slovakia and Poland; river and coastal flood catastrophe models for Scandinavia (Sweden river flooding, Norway river and coastal flooding); river flood catastrophe models for South-eastern Europe covering Romania and Bulgaria, Slovenia, Serbia, Croatia, Bosnia-Herzegovina, Montenegro,  and the parts of Moldova and Ukraine located within the Danube River Basin. Hydro-GIS Ltd has also contributed to the development of a German Storm Surge Model for the North Sea and Baltic sea coasts for use by the GDV (German Insurance Association).
Flood catastrophe model coverage (green shading)
Flood catastrophe model coverage (green shading)
Dr Harvey Rodda, Director of Hydrology at Hydro-GIS Ltd also led the conceptual development of the first RMS UK flood model and developed flood risk models for the Czech Republic and Slovakia following the 2002 Central European floods. Not only are Hydro-GIS staff able to develop flood risk models but are well placed to provide independent assessments of commercial flood catastrophe modelling software where little detail of the structure of the hazard model is provided by the vendors.

Central and Eastern European Flood Catastrophe Model
The Central and Eastern European (CEE) model was developed by Hydro-GIS Ltd for Aon, initially in 2004/5 but included updates in 2007 and 2008. The model covered the risk of flooding from major rivers in Austria, Hungary, the Czech Republic, Slovakia and Poland, and had the following features:
  • Modelled a total of 173 river reaches including on-line lakes and reservoirs (see below);
  • Based on hydrological data from 62 historical flood events;
  • Flood depth and extents mapped for over 2000 synthetic events;
  • Mapping generated at 25m grid cell resolution for the Czech Republic, 100m grid cell resolution for other countries;
  • Included rainfall, snowmelt and ice jam flood events all with defence failure scenarios;
  • Flood depth provided for each event on a post-code basis.
The CEE flood model study area and  river network
The CEE flood model study area and river network
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Extreme Rainfall

One objective of the joint Oxford University/Hydro-GIS Ltd research project has been the compilation of an extreme rainfall digital archive for the British Isles. The outcome, known as the British Rainfall Digital Archive (BRDA) is the most comprehensive resource on historical extreme rainfall, including
  • over 28,000 observations of extreme rainfall back to the year 1866;
  • over 1000 pages of text and eye-witness accounts describing the rainfall events and associated impacts such as flooding;
  • over 250 rainfall maps and photographs.

The BRDA records are far more comprehensive than digital records available from other organisations such as the Met Office and Environment Agency. The Met Office has digital records for most of its network of rain gauges back to 1961, then further back in time the number of gauges for which digital data is available rapidly drops to only a few hundred by the year 1900. By contrast the BRDA has records from over 4000 gauges as far back as 1900. The BRDA data can be used to enhance a range of studies such as flood risk assessments, historical flooding studies, and insurance reports. It can provide more detail on the flood risk at a site and particularly the risk of surface water flooding directly from rainfall.

Hydro-GIS Ltd licence the BRDA for commercial purposes. Please refer to our Products page for more information.

Example of a rain gauge search around Abingdon
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Flood Risk Assessments and Related Studies

Hydro-GIS Ltd undertakes a range of hydrological work on the local scale for other professionals such as architects, planners, agricultural consultants, property owners, local action groups, insurance companies and local authorities. This work includes:
  • Flood risk assessment for developments deemed to be at risk of flooding;
  • Flood risk assessments for developments which could pose an increased risk of flooding for neighbouring properties;
  • Sustainable drainage system (SuDS) design;
  • Hydrological reports in order to gain credits through the Code for Sustainable Homes;
  • Flood risk reports to assist with buying, selling or insuring of property;
  • Reports to assist with insurance claims;
  • Advice on flood mitigation measures;
  • Local flooding problems;
  • Expert witness and case reports for planning inquiries.
Our staff members are highly experienced in the standard methodology often required for these projects such as the Flood Estimation Handbook, IH Report 124, and ADAS 345 and have completed the CIRIA Designing SuDS course. We also undertake topographic and river channel cross section surveys. We have a detailed understanding of the Environment Agency (EA) flood risk maps. It is often the case that the Environment Agency maps as shown on the internet do not provide an entirely accurate indication of flood risk because they were generated using a very general approach. More detailed studies undertaken for a specific site can give a much better assessment of the risk.

Hydro-GIS Ltd has undertaken flood risk assessments at a range of scales, locations, and environments where the proposed development has been shown to be in an area of flood risk or may increase the risk of flooding to neighbouring properties. Projects have included the change of use of existing property, development of single dwellings to large scale rural developments such as stud farms, fish farms, dairy farms and horticultural areas.

Hydro-GIS Ltd also licences the British Rainfall Digital Archive, an archive of extreme rainfall data based on observations going back to 1866. This historical data can be used to provide a fuller assessment of flood risk at a site.

Nottingham University Flood Risk Assessment

Hydro-GIS Ltd was requested to provide a detailed flood risk assessment for a site at Nottingham University which was shown to be a high risk of flooding according to the EA flood zone maps. The study was required in order to continue to provide insurance cover for the property.  The more detailed study we undertook confirmed the risk of flooding from both river flooding and surface water flooding to be low and that it was a viable site to offer insurance. Specific activities included:
  • Visiting the site to survey floor levels and identify routes of flood water ingress to the building;
  • An in depth review of existing EA flood risk mapping;
  • An investigation of historical flooding in the area;
  • Combining modelled EA flood levels with a digital terrain model to generate more accurate flood maps;
  • Using GIS to define surface water flow pathways.

Mapping of the predicted flood extent for the study site using GIS.
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GIS Applications

Geographical Information Systems refers to a computer based capability for the manipulation of spatial (geographical) data. It is far more than an electronic map since any feature displayed in GIS also includes attribute data. Also GIS enables the overlaying of many data layers and handles data in raster, vector, and tabular formats.

Hydro-GIS Ltd has considerable expertise in the field of GIS which dates back to the early 1990s when hydrological and water quality models were developed within a GIS interface.

Today we use Arc GIS/Arc Info, the most advanced and widely used professional GIS software. GIS often provides a basis for many of our projects and we are regularly included in project teams specifically to provide GIS expertise.
Common GIS applications include:
  • Producing maps at a range of scales;
  • Thematic mapping where particular features are classified by their attributes;
  • Generating digital terrain models;
  • Display and analysis of remote sensing data;
  • Derivation of hydrological model parameters using GIS such as catchment boundaries, different soil and land use areas;
  • Flood depth and extent mapping;
  • Modelling flow pathways based on surface topography;
  • Re-formatting of data e.g. digitising paper maps, importing from AutoCAD.
In addition Hydro-GIS provide independent and bespoke GIS courses focussing on the application of GIS in the environmental sector.

Wetland Ecosystem Study

As part of a team working on a DEFRA funded study on the evaluation of wetland ecosystem services (2007-8) Hydro-GIS Ltd provided a range of GIS support collecting and generating data for the Otmoor wetland site, approximately 10km north-east of Oxford, and the wider River Ray catchment area in which Otmoor is located. In this study GIS was not only used for mapping and spatial analysis but also as a means of storing data associated with mapping such as soil and land survey information, data measurements from sampling locations, and photographs.
  • Mapping of land use, land ownership, geology and soils;
  • Generating a digital terrain model from LiDAR data;
  • Digitising the drainage network;
  • Flood depth and extent modelling using a simplified 2-d cell based approach;
  • Producing annotated mapping of questionnaire survey results;
  • Calculating lengths of footpaths over particular land uses.
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Research and Academic Links

Hydro-GIS Ltd has a number of well established links with research and academia.

A major research project was undertaken jointly between Hydro-GIS Ltd and the Department of Engineering Sciences at Oxford University over 2007-8. The project entitled “Quantifying Flood Risk of Extreme Events using Density Forecasts Based on a New Digital Archive and Weather Ensemble Predictions” made use of extreme UK rainfalls dating back to 1866 to test new mathematical modelling techniques to be used in weather forecasting. This was funded through the NERC FREE (Flood Risk from Extreme Events) programme. A number of publications resulted from this project:
  • Rodda, H.J.E., Little, M.A, Wood, R. G., MacDougall, N. and McSharry, P.E. 2009. A digital archive of extreme rainfalls in the British Isles from 1866 to 1968 based on British Rainfall. Weather, Vol 64, No. 3, 71-75.
  • Little M.A., Rodda H.J.E, McSharry P.E. (2008), Bayesian Objective Classification of Extreme UK Daily Rainfall for Flood Risk Applications, (2008), Hydrology and Earth Systems Sciences Discussion, 5:3033-3060.
  • Rodda, J. C., Little, M.A., Rodda, H. J. E., and McSharry, P.E. 2010. A Comparative Study of the Magnitude, Frequency and Distribution of Intense Rainfall in the United Kingdom, Int. J. Climatol. 30:1776-1783.
Dr Harvey Rodda gives a flood hazard course as part of the MSc in Geophysical Hazards, Department of Earth Sciences, University College London. The course includes 18 lectures, a field trip, training on the Flood Estimation Handbook software, exams and supervision of dissertations.

Dissertation topics include river and coastal flood studies, reconstruction of historical flood events and the impacts of climate change. Often these have prompted further internal research, such as flash flooding in SW England:
  • Rodda, H.J.E. and Bailey, P. 2006. An Assessment of Flash Flood Risk in South-West England Using the Reconstruction of Historical Events. Proceedings of the EGU General Assembly, Vienna, April 2006.
Currently Hydro-GIS Ltd is continuing research into methods of predicting surface water flooding from agricultural land (Greenfield runoff). The standard approved method which is currently included in the EA/DEFRA SuDS guidelines produces estimates of the 1 in 100 year peak flow in the order of 20-40 litres per second per hectare. It is common to see water streaming off small areas of agricultural land in much greater quantities following fairly moderate rainfall. Recent research has found the standard method to be a significant underestimate compared with data from field experiments. This has considerable implications on the cost and effectiveness of SuDS designs.
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What about Water?

Dr. John Rodda, Associate Director of Hydro-GIS Ltd has published this article in the light of recent interest in water recources management.

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The locations of the photos in the 2013 Hydro-GIS Ltd calendar are revealed:

List of Calender locations
Front Piece Thuner See, Switzerland
January River Thame in flood,  Oxfordshire
February Bridge at Goring Weir, Oxfordshire
March Otmoor Nature Reserve, Oxfordshire
April Xi'an Pagoda Gardens, China
May Yellow River Valley, near Hangcheng, China
June Harlyn Bay, Cornwall
July Olympic Rowing Lake, Eaton Dorney, Berkshire
August Thuner See, Switzerland
September Lymington River, New Fores
October Stellisee, Rothorn near Zermatt, Switzerland
November River Thames in flood, Oxfordshire
December Bournemouth Pier, Dorset

Dr Harvey Rodda has been supervising dissertations for six MSc students from University College London Department of Earth Sciences. The topics include flood mapping in Columbia and China, dam breach analysis for UK reservoirs, coastal flood risk at Worthing, a reconstruction of the 1955 fluvial flood in Weymouth and a comparison of the flood risk to roman towns with the current day urban extents.

Hydro-GIS Ltd has provided evidence to achieve a successful planning appeal  for a development site in Oxfordshire where the flood risk had been incorrectly mapped by the Environment Agency. Using GIS techniques the areas likely to flood at incremental flood depths were mapped, which proved that the development site was the highest land in the surrounding  village area despite the EA flood outline showing the land was at risk of flooding and the neighbouring properties were not.

A search of the British Rainfall Digital Archive has been undertaken for BBC Wales to assist with a programme looking at flooding following the floods in Cerdigion earlier this year.

Dr Harvey Rodda presented a paper at the British Hydrological Symposium held in Dundee in July on surface water flooding in rural areas (see photo). This provided observations from field experiments to demonstrate how the Environment Agency standard method for calculating surface runoff from rural (greenfield) areas is a considerable underestimate. The paper can be downloaded here.

Ju valley The Ju River valley with irrigated lotus flower cultivation beds.

Hydro-GIS Ltd are part of an international team undertaking a feasibility study into the development of a wetland ecotourism site near the confluence of the Ju and Yellow Rivers at Hancheng, Shaanxi Province, China.

Prof John Rodda's expertise has been in high demand as the beginning of a hose pipe ban across much of England coincided with weeks of heavy rain.
In interviews and comments John made clear that the effects of two dry winters on our main water resources are long-lasting and not relieved by a record rainfall in April. Earlier discussions on the drought focussed on potential transfers of water from thE Severn into the Thames basin.


Hydro-GIS Ltd has teamed up with Sayers and Partners LLP (see useful links) to provide the Canadian Centre for Energy Advancement through Technological Innovation (CEATI International Inc) with specialist advice on the various methods of Flood Hazard Estimation concerning the safety of dams.
The British Rainfall Digital Archive, compiled as part of the NERC funded project “Quantifying Flood Risk of Extreme Events using Density Forecasts Based on a New Digital Archive and Weather Ensemble Predictions” has now been uploaded onto the British Atmospheric Data Centre website. Free access to the archive is restricted to the NERC FREE (Flood Risk from Extreme Events) research programme members for a period of 2 years. Otherwise data can be purchased through Hydro-GIS Ltd. Please refer to our Products page for more information.

Staff from Hydro-GIS Ltd attended the final NERC Flood Risk from Extreme Events (FREE) programme meeting at Imperial College, London, on 20th October 2010, and presented a poster on the British Rainfall Digital Archive, which can be downloaded here
Dr. Harvey Rodda attended the UNESCO International Hydrology Conference: The Changing Physical and Social Environment, Hydrologic Impacts and Feedbacks held in San Diego 11-13 October 2010. He presented a paper entitled “An assessment of groundwater seepage zones using remote sensing and GIS based modelling techniques as part of a wetland restoration project in the UK” which discussed some of the initial results from the Lyth Valley Hydrological Survey.  A copy of the presentation can be downloaded here
Hydro-GIS Ltd has been working together with Water Resource Associates for BP to calculate design flood levels for an expansion of their oil terminal on the shore of the Caspian Sea in Azerbaijan. The work has involved the generation of a 1-d ISIS hydrodynamic model to predict 1 in 100 year flood levels for a normally dry wadi and the surrounding area including the effect on potential access road locations, the railway line and coastal highway.
As part of his role as a guest lecturer at University College London, Department of Earth Sciences, Dr. Harvey Rodda has been supervising five MSc dissertations. The dissertation topics were the effects of climate change on the hydrology of glacial fed rivers in the French Alps, the effects of sea level rise on the Ghanaian and German coast, a comparison of GIS based flood mapping techniques with 1-d hydrodynamic modelling approaches, the effect of land use change on stream flow in small agricultural catchments and the use of high resolution field measurements to test the accuracy of standard methods to estimate Greenfield runoff. The last of these topics provided further evidence to demonstrate how inaccurate the current approved Greenfield runoff calculations can be. The predicted 1 in 100 year Greenfield peak flow was exceeded on four occasions over just a two year monitoring period and on two of these the measured flows were almost double the predicted 1 in 100 year flow.
Hydro-GIS Ltd in cooperation with Bioscan UK are undertaking a hydrological assessment of the Lyth Valley, Cumbria on behalf of Natural England. The Lyth valley, on the south-eastern edge of the Lake District, was periodically flooded from rivers, the sea, surface water and groundwater but since the 19th century it has been heavily drained and managed to enable intensive agriculture. The current study will establish the hydrological regime within the valley and investigate all sources of flooding with the aim of considering the impact of changing the water management to allow the valley to return to its natural state. Hydro-GIS Ltd are undertaking hydrological modelling, a GIS based  analysis including the interpretation of an aerial thermal survey and field monitoring. The project is due for completion by March 2011
Dr Harvey Rodda presented the Digitising of British Rainfall Heavy Events at the Royal Meteorological society meeting on 17th April 2010 to commemorate 150 years of the British Rainfall Organisation. A copy of the presentation can be accessed from the Royal Meteorological Society website
Hydro-GIS Ltd are now offering specialist independent GIS training in environmental consultancy as a 2-day introductory GIS course tailored to  clients needs and requirements. We can also provide independent advice on different GIS packages.
pictureHydro-GIS Ltd
10 Coles Lane
OX44 7SY
United Kingdom
Telephone Number: +44 (0)1865 400675
Mobile Number: +44 (0) 7971 108980
E-mail: [email protected]


¬©Hydro-GIS Ltd 2011 Registered Office: The White House, Mill Road, Goring-on-Thames, RG8 9DD
Company Registration Number: 5206026
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