Designing for surface water runoff control : end-user requirements in Ireland

Abstract

Since 1975, flood estimation in Ireland has generally followed methods as outlined in the Flood Studies Report (Natural Environment Research Council, 1975). An update of this for conditions in the Republic of Ireland commenced in 2005 and included research in Urban Catchment Flood Analysis. To inform this work, a scoping study of issues relating to flooding caused by urban runoff was undertaken by a team from the Centre for Water Resources Research at University College Dublin and some of the findings are described in this paper. It focussed on quantitative and qualitative research methods (self-completion questionnaires and Focus Groups) to review the methods of flood estimation for urbanised catchments currently in use in Ireland. It assessed the nature of deficiencies associated with urban-runoff control and identified achievable and realistic objectives for further research. A questionnaire was developed around a number of key themes pertaining to flooding caused by urban runoff and circulated to 291 stakeholders in target sectors that ranged from Engineering Consultancies to Academic Institutions. A total of 100 questionnaires were returned giving a 34% response rate. The study found; (i) a proliferation of methods are used in practice resulting in significant differences between the estimates; (ii) some methods are sometimes being used for inappropriate spatial scales; (iii) there is a lack of clear guidance on the use of the methods and/or associated software packages; (iv) there is little appreciation of the uncertainties associated with the methods and (v) there are significant deficiencies in some of the basic information available. A list of recommendations was produced, to guide the commissioning of future research to improve the methods available to designers.