Hydro-GIS Ltd has compiled a considerable amount of hydrological data as part of the flood catastrophe model development projects. This includes records of maximum flows from hydrological year books, flow-level rating data, flood frequency data and qualitative data providing a chronicle of flood events in the form of historical flood databases.
From 2007-2009 Hydro-GIS Ltd undertook a research project together with Oxford University funded by NERC entitled Quantifying Flood Risk of Extreme Events using Density Forecasts Based on a New Digital Archive and Weather Ensemble Predictions. As part of this project Hydro-GIS Ltd compiled a digital archive of extreme rainfalls in the British Isles with rainfall depths, maps, photographs and eye-witness accounts of the ensuing flooding.
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.