BS 85600-2017 Post-event flood assessments Guidance on investigating flooding incidents《事后洪水评估 洪水事件调查指引》.pdf

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1、BS 85600:2017Post-event flood assessments Guidance on investigating flooding incidentsBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Publishing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued.

2、The British Standards Institution 2017Published by BSI Standards Limited 2017ISBN 978 0 580 93702 6ICS 13.200The following BSI references relate to the work on this document: Committee reference CB/501 Draft for comment 16/30339193 DCAmendments/corrigenda issued since publicationDate Text affected B

3、S 85600:2017 BRITISH STANDARD THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVEDForeword ii1 Scope 1Figure 1 Scope of BS 85600 22 Normative references 23 Terms and definitions 24 Instigating a post-event survey investigation 4Figure 2 Process for dealing with flood reports 55 Desk-based stud

4、y 66 Preparations for site survey 76.1 Health and safety 76.2 Equipment 77 Site survey/investigation 87.1 Elements recorded during a flood event 87.2 Source of the flood event 97.3 Cause of flooding 97.4 Severity and consequences of flood incident 97.5 Operation and performance of assets 108 Effecti

5、veness of response 118.1 Post-event analysis/assessment of data 118.2 Effectiveness of communication of the flood incident 118.3 Effectiveness of response to flooding 129 Learning from the flood event 1210 Compilation and publication of the report 1210.1 Initial draft and consultation with RMAs 1210

6、.2 Publication of final report 13Annex A (informative) Organizations potentially involved in a flood response 14Annex B (informative) Environment Agency Flood Warning Service 14Annex C (informative) Possible template for flood report 15Annex D (informative) Examples of actions that might be recommen

7、ded in a flood investigation report 16Bibliography 19Contents PageSummary of pagesThis document comprises a front cover, and inside front cover, pages i to ii, pages 1 to 19, an inside back cover and a back cover.BRITISH STANDARD BS 85600:2017 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERV

8、ED IForewordPublishing informationThis British Standard is published by BSI Standards Limited, under licence from The British Standards Institution, and came into effect on 31 July 2017. It was prepared by Technical Committee CB/501, Flood Risk thresholds for different levels of investigations based

9、 on the communities, businesses and infrastructures affected (e.g. domestic and commercial buildings, utilities, road and rail networks); the most useful information to collect; the organizations to contact to supply or corroborate the information; and the preparation of a report containing informat

10、ion collected and initial recommendations for risk management authorities.NOTE In England and Wales, Section 19 of the Flood and Water Management Act 2010 1 requires Lead Local Flood Authorities to investigate and publish reports on significant flood incidents. The recommendations of this British St

11、andard go beyond the legal requirements of Section 19, but provide a useful basis for informing such reports. No legal requirement for post-flood surveys exists in Scotland or Northern Ireland (NI). In Scotland, such reporting is carried out on an ad hoc basis only, with an annual report to Parliame

12、nt on flood incidents and affected communities, produced by Scottish Government officials. In Northern Ireland, post flood investigations are carried out as a matter of course where there is flooding from a watercourse only. In both countries good practice is followed for the surveys, although it is

13、 recognized that some form of technical standardization would be of benefit.This British Standard is applicable to investigation of natural sources of flooding, rather than failure of structures or other assets.This British Standard does not give guidance on resolving flooding or what measures to ta

14、ke to prevent flooding from occurring in the future (see Figure 1).This British Standard is intended to be used by flood risk management authorities and consultants engaged to undertake post-flood investigations.BRITISH STANDARD BS 85600:2017 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVE

15、D 1Figure 1 Scope of BS 856002 Normative referencesThere are no normative references in this document.3 Terms and definitionsFor the purposes of this British Standard, the following terms and definitions apply.3.1 close proximityreasonable assumption that the properties affected were flooded from th

16、e same source or combination of sources, such as surface water and groundwater acting together3.2 flood incidentoverflow of water onto land which is usually dryNOTE The various sources of flooding are defined in 3.3.3.3 flood sources3.3.1 coastal/estuarine floodingflooding that results from sea leve

17、ls exceeding the natural or constructed bank or defence level of coasts and estuaries, typically caused by storms at sea raising sea and wave levels, which can combine with periods of high river flows in estuariesBS 85600:2017 BRITISH STANDARD2 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESER

18、VED3.3.2 internal floodingflooding arising from flood water entering a commercial or residential propertyNOTE Property includes basements and ground level floors, garages if these are within the fabric of the building and occupied static caravans and park homes, but not tents.3.3.3 groundwater flood

19、ingflooding that occurs when the water table (the water level below ground) comes close to and/or above the ground surface levels, typically caused by prolonged periods of above average rainfall over weeks and months3.3.4 river floodingflooding resulting from river levels exceeding the natural or co

20、nstructed bank or defence level of a river or stream, typically caused by prolonged and/or heavy rainfall across catchments over days and weeks3.3.5 sewer floodingflooding caused by a blockage or overflow in a sewer, or capacity issues, or electro-mechnical failure of the pumping stationsNOTE Includ

21、es flooding from storm/surface water and combined sewers.3.3.6 surface water/pluvial/urban floodingflooding from intense rainfall falling on impermeable or saturated surfaces and/or exceeding the ability of any drainage channel to manage the flows, typically caused by short period storms over a matt

22、er of hours or less3.4 hydrometric datadata that describe the flood event in terms of incident rainfall, water levels and flowsNOTE These may also include data on catchment conditions such as soil moisture deficit or snow cover, and whether frozen ground existed at the time of the flood.3.5 lead loc

23、al flood authority (LLFA)local authority responsible for taking the lead coordinating role on local flood risk managementNOTE In England, this is a unitary authority or a county council. In Wales, this is a county council or a county borough council.3.6 local sources of floodingflooding from surface

24、 water, groundwater and watercourses (see 3.10)NOTE See 3.3.3.7 riparian ownerperson who owns land or has property adjacent to a watercourse, whether open or culverted, running through their property3.8 risk management authority (RMA)Environment Agency, lead local authority, district council for an

25、area for which there is no unitary authority, internal drainage board, water utility or highway authoritySOURCE: Flood and Water Management Act 2010 1, Section 6(13), modifiedBRITISH STANDARD BS 85600:2017 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVED 33.9 Sewers3.9.1 combined sewerunde

26、rground pipes which collect both surface water runoff and foul wastewater3.9.2 foul sewerseparate underground pipe system designed specifically for transporting foul wastewater from houses and commercial buildings for treatment or disposal3.9.3 surface water sewerseparate underground pipe system des

27、igned specifically for transporting excess rain and surface water from houses, commercial buildings and roads for treatment or disposalNOTE A surface water sewer can be public (owned by a water and sewerage company) or private/un-adopted (owned by the landowner or management company).3.10 Watercours

28、esNOTE Watercourses include all rivers and streams and all ditches, drains, cuts, culverts, dikes, sluices, sewers (other than public sewers) and passages, through which water flows.3.10.1 main riverwatercourse or river shown on a Main River Map for England or WalesNOTE In Scotland and Northern Irel

29、and, “main river“ has not been defined.3.10.2 ordinary watercoursewatercourse that is not part of a main riverNOTE Examples include smaller brooks, drainage channels, ditches, cuts, dykes, sluices, soughs or culverts that might only convey water for a short length of time in a year.4 Instigating a p

30、ost-event survey investigationFlood events should be investigated in accordance with the procedure set out in Figure 2.The following information should, where possible, be obtained when a flood incident is first reported:a) severity/nature of flooding;b) residential/commercial properties/infrastruct

31、ure affected;c) source of flooding;d) any time-critical hydrometric data;e) frequency of flooding;f) depth/level of flooding; andg) cause of flooding.When considering if it is necessary or appropriate to investigate a flood event, each flood incident should be assessed on a case by case basis, revie

32、wing the severity of the incident, the number and type of properties/assets (homes, businesses and significant infrastructure) affected, and the frequency of such an occurrence. In the case of a major or widespread flood incident, it will be necessary to prioritize the order of undertaking the flood

33、 surveys and, where appropriate, to consult with other responsible organizations.Investigations should be proportionate to the scale of flood being considered.BS 85600:2017 BRITISH STANDARD4 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVEDFigure 2 Process for dealing with flood reportsThe

34、following are guideline thresholds for determining the need for an investigation, but can vary depending on whether the area(s) affected is rural or urban and whether there is any ambiguity as to the source of the flooding:1) flooding of significant infrastructure (hospital, school, utilities, treat

35、ment works, etc.);2) flooding of a key transport link, e.g. primary routes (A-roads and motorways), key rail links;BRITISH STANDARD BS 85600:2017 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVED 53) internal flooding of one or more premises on more than one occasion in the past five years

36、(excluding gardens and detached garages/out-buildings, but including integral garages); and4) internal flooding of five or more properties in close proximity during a single incident.If any of the criteria are met then a flood investigation should be commenced, taking account of the severity and ext

37、ent of flooding (to inform timescales and resources). If the criteria are not met, then this fact and the decision not to investigate should be recorded. The recorded incidents should determine the initial scope and methodology for the survey(s) (one incident might involve several different surveys)

38、, and the decision as to whether the survey will involve a desk study and/or a site visit. This should involve identifying the means of capturing the data and in what format they should be recorded and stored to ensure the information can be viewed and shared for use by any relevant parties in the f

39、uture.5 Desk-based studyWhere necessary, an initial data gathering exercise should be conducted to inform the requirements of the site survey (see Clause 6 and Clause 7). Following the site survey a more in-depth, desk-based study should be used to complete the collation of all relevant information.

40、The following information may be obtained, where available and relevant, as part of a desk-based study:a) main parties involved (see Annex A);b) location of event (including catchment or coastal area);c) identification of the catchment of the area concerned (including contour mapping and assessment

41、of topography);d) location in relation to Environment Agency flood map and LLFA spatial datasets;e) location in relation to Environment Agency national surface water map;f) land use (e.g. residential, agricultural);g) geology and site ground conditions (e.g. permeable/impermeable);h) weather conditi

42、ons and records during the flood event;i) relevant and sufficient hydrometric data to undertake an appropriate hydrological and hydraulic analysis, e.g. for the determination of the return period or likelihood of occurrence of the event;j) asset register, including structures and features which coul

43、d have an effect on flood risk;k) asset condition before and after the flood, level and frequency of maintenance, etc., level and position of assets (e.g. number of road gullies, size of sewers, missing ditches);l) historic mapping, e.g. good illustration of watercourse location and route of flow;m)

44、 history of flooding historic, similar flood events to define a pattern;n) impact on transport infrastructure (public transport/road closures/school closures/requests for assistance, etc.;o) land ownership to inform the site survey;p) any recent developments or changes in land use, including possibl

45、e loss of flood storage;q) assessment of drainage systems and watercourses over the entire catchment, if appropriate; andr) media coverage and any video footage of the flooding.BS 85600:2017 BRITISH STANDARD6 THE BRITISH STANDARDS INSTITUTION 2017 ALL RIGHTS RESERVED6 Preparations for site survey6.1

46、 Health and safetyCOMMENTARY ON 6.1If the site survey begins a day or two after the notification, the flooding might not have receded. After a week infrastructure could still be affected, which might be dangerous.In addition to obtaining the necessary permissions, other people might be on site, e.g.

47、 damage management consultants and loss adjusters, and this is another source/layer of hazard.It is therefore important when sending someone to conduct a survey that they identify and record potential risks and implement the measures necessary to keep themselves safe.6.1.1 A risk assessment should b

48、e performed and control measures put in place consistent with ensuring the health and safety of the person(s) conducting the flood survey/investigation and others.NOTE Attention is drawn to The Health and Safety at Work etc. Act 1974 2 and the Management of Health and Safety at Work Regulations 1999

49、 3.6.1.2 An estimate of each potential risk should be made, which might include the following:a) working on or near water;b) adverse weather;c) damage to infrastructure, such as bridges;d) potential contamination;e) electrical hazards;f) hostile situations.6.1.3 The risks identified may be mitigated by:a) current weather and flood forecasts;b) pre-emptive asset inspections (to remove obstructions etc.);c) effective planning and preparation;d) a flood briefing for all persons undertaking the site survey;e) a buddy system, with team contac