SIST EN 15843:2010
(Main)Water quality - Guidance standard on determining the degree of modification of river hydromorphology
Water quality - Guidance standard on determining the degree of modification of river hydromorphology
This European Standard provides guidance on characterizing the modifications of river hydromorphological features described in EN 14614. Both standards focus more on morphology than on hydrology and continuity, and on lateral and longitudinal continuity rather than on vertical continuity which is difficult to measure. This standard will enable consistent comparisons of hydromorphology between rivers within a country and between different countries in Europe, providing a method for broad-based characterization across a wide spectrum of hydromorphological modification of river channels, banks, riparian zones and floodplains. Its primary aim is to assess "departure from naturalness" as a result of human pressures on river hydromorphology, and it suggests suitable sources of information (see Table A.1) which may contribute to characterizing the modification of hydromorphological features. In doing so, it does not replace methods that have been developed for local assessment and reporting. Decisions on river management for individual reaches or catchments require expert local knowledge and vary according to river type.
Wasserbeschaffenheit - Anleitung zur Beurteilung von Veränderungen der hydromorphologischen Eigenschaften von Fließgewässern
Diese Europäische Norm gibt eine Anleitung zur Beurteilung von Veränderungen der in EN 14614 beschriebe¬nen hydromorphologischen Eigenschaften von Fließgewässern. Diese Norm ermöglicht eine einheitliche, allgemeine Beschreibung eines breiten Spektrums hydromorphologischer Veränderungen von Gewässerlauf, Uferzone und Überschwemmungsgebiet. Vorrangiges Ziel ist eine Einschätzung der „Abweichung von der natürlichen Beschaffenheit“ als Ergebnis der Belastung der Hydromorphologie von Fließgewässern durch den Menschen. Es werden geeignete Informationsquellen genannt, die bei der Beschreibung von Veränderungen hydromorphologischer Eigenschaften hilfreich sein können. Durch diese Vorgehensweise werden keine Verfahren ersetzt, die für eine Vorortaufnahme und bewertung entwickelt wurden. Entscheidungen über die Bewirtschaftung bestimmter Gewässerabschnitte oder Teileinzugsgebiete erfordern spezielle Ortskenntnisse und unterscheiden sich in Abhängigkeit vom Fließgewässertyp.
Qualité de l'eau - Guide pour la détermination du degré de modification de l'hydromorphologie des rivières
La présente Norme européenne prodigue des conseils quant à la caractérisation des modifications des caractéristiques hydromorphologiques des rivières décrites dans l'EN 14614. La norme permet une caractérisation généralisée et cohérente sur tout un large spectre de modifications hydromorphologiques affectant les chenaux des rivières, les berges, les zones riveraines et les plaines d'inondation. Elle a pour objectif principal d'évaluer « l'écart par rapport au naturel » dû aux pressions humaines exercées sur l'hydromorphologie des rivières et suggérer des sources adéquates d'informations qui puissent contribuer à caractériser la modification des caractéristiques hydromorphologiques. Ce faisant, elle ne remplace pas les méthodes qui ont été mises au point pour l'évaluation locale et la présentation de rapports. Les décisions relatives à la gestion de rivières pour des tronçons ou bassins-versants individuels exigent des connaissances locales d'expert et varient en fonction du type de rivière.
Kakovost vode - Smerni standard za določanje stopnje spreminjanja hidromorfoloških značilnosti vodotokov
Ta evropski standard zagotavlja vodilo za karakterizacijo spreminjanja hidromorfoloških značilnosti vodotokov, opisanih v EN 14614. Oba standarda se bolj osredotočata na morfologijo kot hidrologijo in kontinuiteto ter na lateralno in longitudinalno kontinuiteto in ne na vertikalno kontinuiteto, ki jo je težko meriti. Ta standard bo omogočil konsistentno primerjavo hidromorfoloških značilnosti med vodotoki v državi in med različnimi državami v Evropi, saj prepisuje metodo široko zasnovane karakterizacije na širokem spektru spreminjanja hidromorfoloških značilnosti rečnih kanalov, bregov obrežnih pasov in naplavnih ravnic. Njegov temeljni cilj je ocenjevanje »odklona od naravnosti«, ki je posledica človeških pritiskov na hidromorfološke značilnosti vodotokov, hkrati pa omenja primerne vire informacij (glej Preglednico A.1), ki lahko prispevajo h karakterizaciji spreminjanja hidromorfoloških značilnosti. Pri tem ne nadomešča metod, ki so bile razvite za lokalno ocenjevanje in poročanje. Odločitve o upravljanju vodotokov za posamezne dele rek med dvema zavojema ali rezervoarje zahtevajo lokalno strokovno znanje in se razlikujejo v skladu z vrsto reke.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Anleitung zur Beurteilung von Veränderungen der hydromorphologischen Eigenschaften von FließgewässernQualité de l'eau - Guide pour la détermination du degré de modification de l'hydromorphologie des rivièresWater quality - Guidance standard on determining the degree of modification of river hydromorphology13.060.45Preiskava vode na splošnoExamination of water in generalICS:Ta slovenski standard je istoveten z:EN 15843:2010SIST EN 15843:2010en,fr,de01-julij-2010SIST EN 15843:2010SLOVENSKI
STANDARD
SIST EN 15843:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 15843
January 2010 ICS 13.060.45 English Version
Water quality - Guidance standard on determining the degree of modification of river hydromorphology
Qualité de l'eau - Guide pour la détermination du degré de modification de l'hydromorphologie des rivières
Wasserbeschaffenheit - Anleitung zur Beurteilung von Veränderungen der hydromorphologischen Eigenschaften von Fließgewässern This European Standard was approved by CEN on 28 November 2009.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
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Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15843:2010: ESIST EN 15843:2010
EN 15843:2010 (E) 2 Contents Page Foreword .3Introduction .41Scope .52Normative references .53Terms and definitions .54Principle .95Determining the hydromorphological modifications of rivers .96Interpreting and reporting hydromorphological modifications . 11Annex A (normative)
Characterization of river modification based on hydromorphological features . 13Annex B (informative)
Some key points in the development of this European Standard . 23 SIST EN 15843:2010
EN 15843:2010 (E) 3 Foreword This document (EN 15843:2010) has been prepared by Technical Committee CEN/TC 230 “Water analysis”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2010, and conflicting national standards shall be withdrawn at the latest by July 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. WARNING — Safety issues are paramount when surveying rivers. Surveyors should conform to EU and national Health and Safety legislation, and any additional guidelines appropriate for working in or near rivers.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 15843:2010
EN 15843:2010 (E) 4 Introduction This European Standard will enable broad comparisons to be made of river hydromorphological modifications throughout Europe (e.g. for reporting by the European Environment Agency). The assessment of river "quality" in Europe has evolved over the past 20 years. From its original focus on organic pollution it now relies on methods for analysing a range of chemical and biological attributes. More recently, several European countries have developed systems for evaluating the hydromorphological features of rivers. The EC Water Framework Directive (WFD) has reinforced the need for this broader view of river "quality" through its requirement for determining "ecological status" based on macrophytes, phytobenthos, invertebrates and fish. The Directive also requires that hydromorphological and physico-chemical conditions should be suitable for supporting biological communities, although hydromorphology is only classified at high status. EN 14614, Water Quality
Guidance standard for assessing the hydromorphological features of rivers describes a protocol for field survey and feature recording, whereas this standard gives guidance on assessing the modification of river hydromorphological features. It focuses especially on human pressures that affect rivers; thus, it may be helpful for implementing the WFD by indicating the extent to which these pressures might have caused a departure from hydromorphological reference conditions. Although the procedure described in this standard enables the hydromorphological characterization of rivers, it does not attempt either to describe methods for defining high status for hydromorphology under the WFD or to link broadscale hydromorphological classification to assessments of ecological status. In addition to its relevance to the WFD, this standard has applications also for nature conservation, environmental impact assessment, river basin management, flood risk assessment (e.g. the EC Floods Directive) and setting targets for river restoration work.
SIST EN 15843:2010
EN 15843:2010 (E) 5 1 Scope This European Standard provides guidance on characterizing the modifications of river hydromorphological features described in EN 14614. Both standards focus more on morphology than on hydrology and continuity, and on lateral and longitudinal continuity rather than on vertical continuity which is difficult to measure. This standard will enable consistent comparisons of hydromorphology between rivers within a country and between different countries in Europe, providing a method for broad-based characterization across a wide spectrum of hydromorphological modification of river channels, banks, riparian zones and floodplains. Its primary aim is to assess "departure from naturalness" as a result of human pressures on river hydromorphology, and it suggests suitable sources of information (see Table A.1) which may contribute to characterizing the modification of hydromorphological features. In doing so, it does not replace methods that have been developed for local assessment and reporting. Decisions on river management for individual reaches or catchments require expert local knowledge and vary according to river type. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 14614, Water quality — Guidance standard for assessing the hydromorphological features of rivers 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 aquatic macrophytes larger plants of fresh water which are easily seen with the naked eye, including all aquatic vascular plants, bryophytes, stoneworts (Characeae) and macro-algal growths NOTE This definition includes plants associated with open water or wetlands with shallow water. [EN 14614:2004, 2.1] 3.2 attribute specific recorded element of a hydromorphological feature (e.g. "boulders" and "silt" are substrate attributes; "sheet piling" and "gabions" are attributes of engineered banks) [EN 14614:2004, 2.2] 3.3 bank permanent side of a river or island, which is above the normal water level and only submerged during periods of high river flow [EN 14614:2004, 2.4] NOTE In the context of this European Standard, the top is marked by the first major break in slope, above which cultivation or development is possible. SIST EN 15843:2010
EN 15843:2010 (E) 6 3.4 berm natural or artificial shelf within a river that is exposed above water level during low flows, but is submerged during high flows [EN 14614:2004, 2.6] 3.5 bog wetland, fed by atmospheric precipitation, in which the vegetation communities (frequently dominated by Sphagnum mosses) form peat over long periods of time [EN 14614:2004, 2.7] 3.6 braiding course of a river naturally divided by deposited sediment accumulations, characterised by at least two channels which often change their course regularly [EN 14614:2004, 2.8] 3.7 compaction consolidation of the river bed through physical, chemical or biological processes [EN 14614:2004, 2.10] 3.8 culvert arched, enclosed or piped structure constructed to carry water under roads, railways and buildings 3.9 ecological status expression of the quality of the structure and functioning of aquatic ecosystems, expressed by comparing the prevailing conditions with reference conditions NOTE As classified in accordance with Annex V of the EC Water Framework Directive. [EN 14614:2004, 2.12] 3.10 floodplain valley floor adjacent to a river that is (or was historically) inundated periodically by flood waters [EN 14614:2004, 2.14] 3.11 gabion wire basket containing stones, used for river-bed or bank protection [EN 14614:2004, 2.16] 3.12 hard materials/engineering bank protection using artificial materials such as concrete, sheet piling or bricks NOTE See "soft materials". SIST EN 15843:2010
EN 15843:2010 (E) 7 3.13 hydromorphology physical and hydrological characteristics of rivers including the underlying processes from which they result [EN 14614:2004, 2.18] 3.14 hydro-peaking rapid and frequent fluctuations in flow resulting from hydropower generation to meet peak demands in electricity 3.15 lateral connectivity freedom for water to move between the channel and the floodplain [EN 14614:2004, 2.19] 3.16 lateral movement freedom for a river channel to move across a floodplain [EN 14614:2004, 2.20] 3.17 planform view of river pattern from above (e.g. sinuous, straight) [EN 14614:2004, 2.22] 3.18 reach major sub-division of a river, defined by physical, hydrological, and chemical character that distinguishes it from other parts of the river system upstream and downstream [EN 14614:2004, 2.25] 3.19 reference conditions conditions representing a totally undisturbed state, lacking human impact, or near-natural with only minor evidence of distortion NOTE For waters not designated as heavily modified or artificial, synonymous with "high ecological status" in the Water Framework Directive. [EN 14614:2004, 2.26] 3.20 regrading river widening and deepening and modifying the bed and bank profiles to accommodate increased flows 3.21 reinforcement strengthening of river beds and banks for various purposes (e.g. ford construction, erosion control) using materials such as boulders, sheet piling, geotextiles, etc. 3.22 residual flow
flow remaining in a river after abstraction (e.g. for hydropower generation, water supply, etc.) SIST EN 15843:2010
EN 15843:2010 (E) 8 NOTE A minimum residual flow may be set to protect downstream uses, below which abstraction is not permitted. 3.23 riparian zone area of land adjoining a river channel (including the river bank) capable of directly influencing the condition of the aquatic ecosystem (e.g. by shading and leaf litter input) [EN 14614:2004, 2.29] NOTE In this European Standard, the term "riparian zone" does not include the wider floodplain. 3.24 river type group of rivers that can be broadly differentiated from other groups on the basis of their physical and chemical characteristics (e.g. lowland chalk streams; upland ultra-oligotrophic rivers) [EN 14614:2004, 2.32] 3.25 sheet piling material used for vertical bank protection (e.g. corrugated metal sheets) [EN 14614:2004, 2.34] 3.26 sinuosity degree of deviation from a straight line, defined as channel length/valley length [EN 14614:2004, 2.36] 3.27 soft materials/engineering bank protection using biodegradable materials such as brushwood, reeds or live willows
NOTE See "hard materials". 3.28 substrate material making up the bed of a river [EN 14614:2004, 2.40] 3.29 weir structure used for controlling flow and upstream surface level, or for measuring discharge [EN 14614:2004, 2.41] 3.30 willow spiling method of soft engineering used for strengthening river banks using retaining walls constructed of woven willow stems from which trees will sprout 3.31 woody debris dead woody material that falls into rivers and streams, ranging in size from leaf fragments (fine woody debris) to branches or whole trees (coarse woody debris) SIST EN 15843:2010
EN 15843:2010 (E) 9 4 Principle 4.1 A standard protocol is described for assessing the extent to which the hydromorphological features of river channels, banks, riparian zones and floodplains are modified. These features have been divided into two groups – a larger group of "core features" and a smaller group of "subsidiary features". Core features are used to establish "departure from naturalness" as a result of human pressures on river hydromorphology. Subsidiary features also include some that contribute to habitat quality assessment. The former can be determined without reference to river type using data from field survey, remote sensing, maps or local knowledge, whereas the latter require an understanding of the features to be expected in different types of river. Both this European Standard and EN 14614 focus attention on river features as surrogates for river processes. Those making assessments, therefore, do not need to be trained geomorphologists, although some geomorphological input may be useful in determining the contribution made by subsidiary, type-specific features. 4.2 The principal output from this standard is an assessment of the modification of hydromorphological features of an entire river reach. A definition of the term "river reach" and its relationship with survey units is given in EN 14614. However, the principles in the standard may also be applied to much shorter stretches, such as those requiring restoration, or where near-natural conditions need to be protected. 4.3 To ensure consistency in approach, the main feature categories are the same as those in EN 14614. However, some minor adjustments have been made to the details to help facilitate scoring. 5 Determining the hydromorphological modifications of rivers 5.1 Feature categories Assessments are made for all of the feature categories listed in EN 14614, some of which have been sub-divided into core and subsidiary features (Table 1). Table 1 — Categories of "core" and "subsidiary" features for determining modification Category Core Subsidiary1. Channel geometry
1a Planform 9
1b Channel section (long-section and cross-section) 9
2. Substrates
2a Extent of artificial material 9
2b "Natural" substrate mix or character altered
9
3. Channel vegetation and organic debris
3a Aquatic vegetation management
9
3b Extent of woody debris if expected
9
4. Erosion/deposition character
9
5. Flow
5a Impacts of artificial in-channel structures within the reach 9
5b Effects of catchment-wide modifications to natural flow character 9
SIST EN 15843:2010
EN 15843:2010 (E) 10 Table 1 (continued) Category Core Subsidiary 5c Effects of daily flow alteration (e.g. hydropeaking) 9
6. Longitudinal continuity as affected by artificial structures 9
7. Bank structure and modifications 9
8. Vegetation type/structure on banks and adjacent land 9
9. Adjacent land-use and associated features 9
10. Channel-floodplain interactions
10a Degree of lateral connectivity of river and floodplain 9
10b Degree of lateral movement of river channel
9
5.2 Procedure for scoring 5.2.1 Annex A sets out guidance on how to allocate scores for each feature category. Table A.1 contains two separate procedures for scoring − using score band A with quantitative data, or score band B with qualitative data. Score band A is a five-point scale (1 = lowest degree of modification, 5 = highest degree of modification). Score band B is a three-point scale (1, 3, 5; following the same general approach as for score band A). Users should state which scores have been assigned based on quantitative data and which on qualitative descriptions, as this determines the degree of confidence in the assessment. This note should also be added to any maps produced that show the results of river hydromorphological assessment. An attribute should be left unscored where the user is not confident in allocating a score.
5.2.2 Where the majority of scores have been derived from five-band scales users may wish to retain the five bands. Where the majority have been derived from three-band scales users may wish to change the five-band scores to three-band scores as follows:
Five-band score Three-band score 1 1 2 1 3 3 4 5 5 5
5.2.3 For those features where scoring 1 = 0 % to 5 % change (features 1, 2a, 7, 8, 9, 10), an asterisk should be added (i.e. 1*) where the recorded change is only 0 % to 1 %. This is to highlight river reaches with extremely low levels of modification. A 1 symbol should be added (i.e. 51) to indicate extreme levels of modification. 5.2.4 The importance of each of the features in Table 1 for geomorphological and ecological functioning will not be the same. However, at present there is insufficient scientific evidence to justify differential weighting of the scores allocated. SIST EN 15843:2010
EN 15843:2010 (E) 11 6 Interpreting and reporting hydromorphological modifications 6.1 Modification scores 6.1.1 Scores should be tabulated as shown in Table 2. This process provides a range of options for different purposes, but shows clearly how each of the three combined scores (options 2, 3 and 4 in Table 2) has been derived.
Table 2 — Options, applications and procedures for reporting hydromorphological modification scores Reporting option Examples of applications Procedure 1: Tabulate 16 scores separately Providing maximum amount of information for river management Score as in Annex A for all features (1a, 1b, 2a, 2b, 3a, 3b, 4, 5a, 5b, 5c, 6, 7, 8, 9, 10a, 10b); do not combine. 2: Create a three-digit code Reporting river modification within the three main hydromorphological quality elements given in the WFD (morphology, flow regime, and longitudinal continuity) but with no attempt to link hydromorphology with biology
Combine the scores for categories 1a, 1b, 2a, 2b, 7, 8, 9, 10a, 10b to create a single mean score for morphology (the first of the three digits). Scores should be rounded up or down to the nearest integer (rounding up any that end in ,5) Report the score for category 5 for flow (the second of the three digits) using 5a, 5b or 5c, whichever has the higher score (i.e. represents the greater impact). Report the score for category 6 for longitudinal continuity (the third of the three digits). [For example, a code of 111 would indicate a river with the lowest degree of morphological modification, near-natural flow, and with no structures inhibiting upstream and downstream movement of sediment and biota.] 3: Group features according to zone Reporting on the three main river zones: "channel", "banks/riparian zone" and "floodplain", as recommended in EN 14614.
Feature categories should be grouped as follows and mean scores calculated for the three zones. Scores should be rounded up or down to the nearest integer (rounding up any that end in ,5): Channel: 1a, 1b, 2a, 2b,
5a, 5b, 5c, 6 Banks/riparian zone: 7, 8 Floodplain: 9, 10a, 10b 4: Produce a single score for the reach assessed Reporting overall hydromorphological modification of a river reach without the detail Take the mean of the 16 scores (see no. 1 in table). Round up or down to the nearest integer. Scores ending in ",5" should be rounded up.
SIST EN 15843:2010
EN 15843:2010 (E) 12 6.2 Assigning classification terms 6.2.1 Where five classes are used, the following terms should be assigned to descriptions of hydromorphological modification, and represented (if required) on a map using the colour codings recommended in EN 14614. Table 3 — Classification terms for five classes Score Class Description Map colour 1 to < 1,5 1 Near-natural Blue 1,5 to < 2,5 2 Slightly modified Green 2,5 to < 3,5 3 Moderately modified Yellow 3,5 to < 4,5 4 Extensively modified Orange 4,5 to 5,0 5 Severely modified Red
6.2.2 Where three classes are used, the following terms should be assigned to descriptions of hydromorphological modification, and represented (if required) on a map using the following colour codings: Table 4 — Classification terms for three classes Score Class Description Map colour 1 to < 2,5 1 Near-natural to slightly modified Blue 2,5 to < 3,5 3 Slightly to moderately modified Yellow 3,5 to 5,0 5 Extensively to severely modified Red
The names used to describe each class (e.g. "near-natural") have been deliberately chosen to be different from terms used in the WFD (e.g. "high", "good") to emphasise that classifications using this standard are unrelated to classifications of ecological status for the WFD. Although the five colours listed in 6.2.1 for reporting hydromorphological modification are the same as those in the WFD, they are also used routinely for reporting other (non-WFD) aspects of environmental quality.
SIST EN 15843:2010
EN 15843:2010 (E) 13 Annex A (normative)
Characterization of river modification based on hydromorphological features Explanation for Table A.1: "Core features" (shown in roman type): those that may be evaluated without reference to river type. "Subsidiary features" (shown in italics): require expert judgement (in some cases geomorphological). The score for each feature should be given an "A" or "B" suffix according to which of the two score bands has been used. N/A = Not applicable. SIST EN 15843:2010
EN 15843:2010 (E) 14 Table A.1 — Protocol
Features assessed Score band A – Quantitative Score band B – Qualitative Guidance Examples of suitable methods/data use 1. Channel geometry 1a: Planform (reach-based) 1 = 0 % to 5 % of reach length with changed planform.
2 = > 5 % to 15 % of reach length with changed planform. 3 = > 15 % to 35 % of reach length with changed planform. 4 = > 35 % to 75 % of reach length with changed planform. 5 = > 75 % of reach length with changed planform. 1 = Near-natural planform. 3 = Planform changes throughout part of the reach. 5 = Planform changed in majority of reach, or reach completely, or almost completely, straightened. In this context, "planform" both to changes in channel sinuosity and to changes in channel braiding or to multiple channels. If possible, use absolute or recorded amounts of change rather than estimates from variety of sources.
Where a river has some artificial sinuosity, but has lost its natural meandering, assign score 5. Consult maps and compare historical with present-day planform where changes have resulted from engineering, etc.
(includes loss of braiding, etc.) (1a/1b). Engineering construction and maintenance work records (1a/1b). Local/management personnel/expert assessment (1b). Survey data (e.g. evidence of regrading), structures installed (e.g. deflectors) (1b). Knowledge of changes to width/depth ratios (1b). 1b: Channel section (long-section and cross-section) (use site and other data and combine for whole reach) If no data for 1b, the score for Channel geometry is 1a by itself.
Keep two elements separate; take worse case 1 = 0 % to 5 % of reach length with changed channel section. 2 = > 5 % to 15 % of reach length with changed channel section. 3 = > 15 % to 35 % of reach length with changed channel section. 4 = > 35 % to 75 % of reach length with changed channel section. 5 = > 75 % of reach length with changed channel section. 1 = Near-natural. No, or minimal, change in cross- and/or long-section. 3 = Moderately altered. Channel partially affected by one or more of the following: regrading, reinforcement, culvert, berm, or clear evidence of dredging causing some changes in width/depth ratio.
5 = Greatly altered. Channel predominantly affected by one or more of the following: regrading, reinforcement, culvert, berm, or clear evidence of dredging causing major change in width/depth ratio.
SIST EN 15843:2010
EN 15843:2010 (E) 15
Table A.1 (continued)
Features assessed Score band A – Quantitative Score band B – Qualitative Guidance Examples of suitable methods/data use 2. Substrates 2a: Extent of artificial material (e.g. concrete, rubble, gabion baskets) 1 = 0 % to 1 % artificial material. 2 = > 1 % to 5 % artificial material. 3 = > 5 % to 15 % artificial material. 4 = > 15 % to 30 % artificial material. 5 = > 30 % artificial material. 1 = No, or minimal, presence of artificial material. 3 = Small to moderate presence of artificial material. 5 = Extensive presence of artificial material. User assesses how the channel sediment is not natural (e.g. increased siltation, gravel compaction/ cementation). Hydromorphological survey information (2a/2b). Observations made by walk-over surveys (2a/2b). Local/management personnel/expert assessment (2b). Observations made during biological sampling. (Includes evidence of sediment running off fields; boulders installed for fish, compaction of gravels, etc.). 2b: "Natural" substrate mix or character altered Feature not scored. 1 = Near-natural mix. 3 = Natural mix/character slightly to moderately altered. 5 = Natural mix/character greatly altered. Record only natural substrates: mud, silt, sand, pebbles, gravel, stones, rocks, organic substrates. NOTE 1 In lowland streams with sandy or loamy substrates the diversity of substrates is restricted to smaller grain sizes. NOTE 2 Recording of substrates might be difficult in larger and turbid rivers and streams, and may need to be estimated approximately. 3. Channel vegetation and organic debris 3a. Aquatic vegetation management Feature not scored. 1 = No vegetation management, or very little (e.g. affecting < 10 % of reach). 3 = Moderate level of vegetation management (e.g. 10 % to 50 % of reach affected by vegetation management at least every two years). 5 = High level of vegetation management (e.g. annual vegetation management affecting > 50 % of reach). Assessments of aquatic vegetation structure should be carried out during the period of active growth. Local knowledge should be used to apply the guidance for scoring in 3a and 3b to situations not specifically covered in the score bands.
SIST EN 15843:2010
EN 15843:2010 (E) 16
Table A.1 (continued)
Features assessed Score band A – Quantitative Score band B – Qualitative Guidance Examples of suitable methods/data use
3b. Extent of woody debris if expected Feature not scored. 1 = Near-natural amount and size of woody debris; no active removal or addition. 3 = Amount and size of woody debris slightly to moderately altered; occasional active removal or addition. 5 = Amount and size of woody debris greatly altered; regular active removal or addition.
Note that the score for management of woody debris can be affected by management within the reach or upstream from the reach. Although scores are given only for woody debris, the presence of other organic debris (e.g. leaf packs) is important and should be noted where it occurs. 4. Erosion/deposition character Presence of in-channel features such as gravel bars, etc. Feature not scored. 1 = Erosion/deposition features reflect near-natural conditions. 3 = Erosion/deposition features reflect moderate departure from near-natural conditions (10 % to 50 % of the features expected are absent). 5 = Erosion/deposition features reflect great departure from near-natural conditions (≥ 50 % of the features expected are absent). In-channel features comprise depositional features (e.g. steps, riffles, bars, islands, shallow waters), and erosional features (e.g. pools, potholes, cliffs-, and also features such as cushions of aquatic plants, large wood, etc. This feature is essentially a measure of the combination of pressures that affect riv
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