3 Scoping 3.1 Introduction The first task is to define the scope of the study. This will establish the purpose of the assessment, the level of assessment and the data requirements to inform decisions. Notifying SEPA that a study is planned for a particular area will allow SEPA to provide advice to feed into the scoping phases. In particular SEPA can advise on known linkages with other studies and can provide details of hydrometric and other data (held by SEPA) for the study area. It is recommended that SEPA’s Strategic Flood Risk team ( strategic.floodrisk@sepa.org.uk ) and the appropriate Regional Flood Risk Planning Manager are contacted to advise that the study is taking place.
This chapter provides guidance for Responsible Authorities in: Developing a conceptual model of a catchment; Identifying opportunities for joint studies; Identifying the appropriate level of complexity for a flood study; Selecting suitable modelling software to meet the study objectives. Further information on scoping Natural Flood Management (NFM) Studies or studies with an NFM component is given in Chapter 12. 3.2 Define Modelling Objective It is important to develop a clear statement of the purpose of the proposed modelling study as this will determine the level of assessment carried out.
The purpose may be for flood mapping to support development planning and management, options assessment for a flood prevention scheme, detailed design etc. Consideration should be given to the required accuracy and level of quality control given the purpose of the model. This should be stated in the Statement of Requirements (SoR). The required study outputs should be listed as part of the modelling objective and further guidance is given in Chapter 15. Potential future uses of the model and outputs should also be considered, as this may enable the model to be built in such a way as to maximise reuse, and will ensure that necessary outputs are supplied.
3.3 Developing a Conceptual Model Key points for Responsible Authorities Develop a conceptual model of flood risk using the source-pathway-receptor- impacts approach. Carry out a catchment walk-over. Review available data to determine the need for any additional data collection. Set out knowledge of the catchment in the SoR. Key points for Contractors Develop and revise the conceptual model of the catchment throughout the study. Describe the conceptual model in the modelling report. Flood Modelling Guidance for Responsible Authorities v1.1 10