Water quality - Guidance standard on assessing the hydromorphological features of transitional and coastal waters

EN 16503 gives guidelines for characterizing the hydromorphology of transitional or coastal (TraC) waters, but does not prescribe detailed methods of assessment. The main aim of this document is to improve the comparability of hydromorphological survey methods, data processing, and the interpretation and presentation of results. This European Standard: a) lists essential features and processes of TraC waters that should be characterized as part of a hydromorphological survey and used for determining hydromorphological condition; b) gives guidance on strategies for collecting and presenting hydromorphological data depending on the resources available and the anticipated use of the assessment; c) describes how to generate data sets appropriate for monitoring and reporting on the condition of Natura 2000 sites designated under the Habitats Directive and the Birds Directive; d) provides guidance on data quality assurance. This European Standard does not deal with biological assessments in TraC waters such as the presence or absence of individual species or community composition, nor does it attempt to link specific hydromorphological features with their associated biological communities. However, it is relevant where plants or other organisms form significant structural elements of the habitat (e.g. saltmarshes, biogenic reefs).

Wasserbeschaffenheit - Anleitung zur Beurteilung der hydromorphologischen Merkmale der Übergangs- und Küstengewässer

Dieses Dokument gibt eine Anleitung zur Charakterisierung der Hydromorphologie von TraC Gewässern. Hauptziel ist es, die Vergleichbarkeit von hydromorphologischen Untersuchungsmethoden, der Datenaufbereitung sowie der Interpretation und Präsentation von Ergebnissen zu verbessern. Übergangsgewässer (z. B. Ästuare, Fjorde, einige Lagunen) sind in allgemeiner Hinsicht weder gänzlich offene Küstensysteme noch in sich geschlossene oder fließende Süßwassergebiete (bezüglich der WRRL  Definition: siehe Abschnitt 2) Ihre Abgrenzungen können durch hydromorphologische Eigenschaften und Diskontinuitäten, durch den Salzgehalt oder jede weitere hydrographische Eigenschaft (z. B. Wassertiefe und Gezeitenregime) definiert sein. Der Begriff „Küstengewässer“ ist bereits für verschiedene rechtliche und politische Zwecke definiert worden (z. B. siehe Abschnitt 2), in dieser hydromorphologischen Norm dagegen werden Küstengewässer als Gewässer definiert, die durch Küsteneigenschaften charakterisiert sind und von Küstenprozessen beeinflusst werden.
Diese Europäische Norm dient zur:
a)   Unterstützung von Umwelt  und Naturschutzbehörden bei der Erfüllung der Anforderungen an die Überwachung nach WRRL und MSRL;
b)   Erstellung geeigneten Datenmaterials für die Überwachungs  und Berichtspflicht der Natura 2000 Gebiete nach der Habitat Richtlinie und der Vogelschutz Richtlinie;
c)   Bereitstellung von Informationen zur Unterstützung anderer Umweltberichtspflichten (z. B. im Zusammenhang mit Biodiversitäts  oder Umweltverträglichkeitsprüfungen);
d)   Unterstützung bei Vorhaben der Bewirtschaftung und Renaturierung.
Diese Europäische Norm:
e)   definiert den Begriff „Hydromorphologie“ sowie andere Fachbegriffe, die sich auf die physikalischen Eigenschaften von TraC Gewässern und deren hydrologischen Regime beziehen;
f)   listet die wichtigsten Eigenschaften und Prozesse von TraC Gewässern auf, die als Bestandteil einer hydromorphologischen Untersuchung beschrieben werden sollten und die zur Bestimmung des hydromorphologischen Zustands dienen können;
g)   identifiziert und definiert die Hauptbelastungen, die europäische TraC Gewässer beeinträchtigen;
h)   gibt eine Anleitung zu Vorgehensweisen bei der Erhebung und der Darstellung hydromorphologischer Daten in Abhängigkeit von den zur Verfügung stehenden Möglichkeiten und dem voraussichtlichen Nutzen der Beurteilung;
i)   liefert eine Anleitung zur Qualitätssicherung von Daten.
Diese Europäische Norm beschäftigt sich weder mit biologischen Beurteilungen von TraC Gewässern, wie dem Vorkommen oder dem Fehlen einzelner Arten oder der Zusammensetzung von Lebensgemeinschaften, noch versucht sie, bestimmte hydromorphologische Eigenschaften mit den dazugehörigen Lebensgemeinschaften zu verknüpfen. Von Bedeutung ist sie jedoch, wo Pflanzen oder andere Organismen signifikante Strukturelemente des Habitats bilden (z. B. Salzwiesen, biogene Riffe).

Qualité de l'eau - Norme guide pour l'évaluation des caractéristiques hydromorphologiques des eaux de transition et des eaux côtières

Le présent document fournit des lignes directrices sur la caractérisation de l’hydromorphologie des eaux côtières et de transition. Son objectif principal est d’améliorer la comparabilité des méthodes de suivis hydromorphologiques, le traitement des données ainsi que l’interprétation et la présentation des résultats. Au sens large, les eaux de transition (c’est-à-dire estuaires, fjords, certaines lagunes) ne sont ni des systèmes côtiers entièrement ouverts ni des zones d’eau douce fermées ou en circulation (pour la définition de la DCE, voir l'Article 2). Leurs frontières peuvent être définies par des éléments hydromorphologiques et des discontinuités, par la salinité ou par toute autre caractéristique hydrographique (par exemple, profondeur d’eau et régime des marées). Le terme « eaux côtières » a été défini à différentes fins d’ordre juridique et politique (par exemple, voir l'Article 2). Toutefois, dans la présente norme hydromorphologique, il désigne des eaux définies par une configuration côtière influencée par des processus côtiers.
La présente Norme européenne est destinée à :
a)   aider les organismes de protection et de conservation de l’environnement à satisfaire aux exigences de surveillance de la DCE et de la DCSMM ;
b)   générer des ensembles de données appropriés pour surveiller et rendre compte de l’état des sites Natura 2000 désignés dans le cadre de la Directive Habitats et de la Directive Oiseaux ;
c)   fournir des informations permettant de satisfaire aux exigences de rapportage sur d’autres aspects environnementaux (par exemple, en relation avec la biodiversité ou l’évaluation de l’impact sur l’environnement) ;
d)   soutenir les initiatives de gestion et de restauration.
La présente Norme européenne :
e)   définit le terme « hydromorphologie » et d’autres termes associés aux caractéristiques physiques des eaux côtières et de transition et leurs régimes hydrologiques ;
f)   répertorie les caractéristiques et processus essentiels des eaux côtières et de transition qu’il convient de caractériser dans le cadre d’un suivi hydromorphologique et d’utiliser pour déterminer l’état hydromorphologique ;
g)   identifie et définit les principales pressions affectant les eaux côtières et de transition européennes ;
h)   donne des lignes directrices sur les stratégies de collecte et de présentation des données hydromorphologiques en fonction des ressources disponibles et de l’usage prévu de l’évaluation ;
i)   fournit des lignes directrices sur les questions d’assurance qualité des données.
La présente Norme européenne ne traite pas des évaluations biologiques en eaux côtières et de transition telles que la présence ou l'absence d'espèces particulières ou la composition de la communauté et ne tente pas d’établir de lien entre des caractéristiques hydromorphologiques spécifiques et les communautés biologiques qui leur sont associées. Toutefois, elle s’applique lorsque des plantes ou d’autres organismes forment des éléments structuraux importants de l’habitat (par exemple, marais salants, récifs biogéniques).

Kakovost vode - Navodilo za ocenjevanje hidromorfoloških značilnosti somornic in obalnih morij

Standard EN 16503 podaja smernice za označevanje hidromorfologije somornic ali obalnih (TraC) morij, vendar ne določa podrobnih metod ocenjevanja. Glavni cilj tega dokumenta je izboljšati primerljivost hidromorfoloških raziskovalnih metod, obdelave podatkov ter razlage in predstavitve rezultatov. Ta evropski standard: a) našteva osnovne značilnosti in procese somornic in obalnih morij, ki naj bi bili označeni kot del hidromorfološke raziskave in se uporabljali pri določanju hidromorfološkega stanja; b) določa navodila za strategije za zbiranje in predstavljanje hidromorfoloških podatkov, odvisno od razpoložljivih virov in pričakovane uporabe ocene; c) opisuje, kako pridobiti podatkovne nize, ustrezne za spremljanje in poročanje o stanju območij Natura 2000, določenih v okviru direktiv o habitatih in pticah; d) podaja navodila za zagotavljanje kakovosti podatkov. Ta evropski standard ne obravnava bioloških ocen v somornicah ali obalnih morjih, kot je ocena prisotnosti ali odsotnosti posameznih vrst ali ocena sestave združb, in si ne prizadeva za povezavo posameznih hidromorfoloških značilnosti z ustreznimi življenjskimi združbami. Vendar velja v primerih, ko rastline ali drugi organizmi tvorijo znatne strukturne elemente habitata (npr. slana močvirja, biogeni grebeni).

General Information

Status
Published
Public Enquiry End Date
28-Feb-2013
Publication Date
28-Sep-2014
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
10-Sep-2014
Due Date
15-Nov-2014
Completion Date
29-Sep-2014

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Anleitung zur Beurteilung der hydromorphologischen Merkmale der Übergangs- und KüstengewässerQualité de l'eau - Norme guide pour l'évaluation des caractéristiques hydromorphologiques des eaux de transition et des eaux côtièresWater quality - Guidance standard on assessing the hydromorphological features of transitional and coastal waters13.060.70Preiskava bioloških lastnosti vodeExamination of biological properties of water13.060.10Voda iz naravnih virovWater of natural resourcesICS:Ta slovenski standard je istoveten z:EN 16503:2014SIST EN 16503:2014en,fr,de01-november-2014SIST EN 16503:2014SLOVENSKI

STANDARD
SIST EN 16503:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16503
August 2014 ICS 13.060.70 English Version

Water quality - Guidance standard on assessing the hydromorphological features of transitional and coastal waters

Qualité de l'eau - Norme guide pour l'évaluation des caractéristiques hydromorphologiques des eaux de transition et des eaux côtières

Wasserbeschaffenheit - Anleitung zur Beurteilung der hydromorphologischen Merkmale der Übergangs- und Küstengewässer This European Standard was approved by CEN on 11 July 2014.

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-CENELEC 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-CENELEC 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16503:2014 ESIST EN 16503:2014

EN 16503:2014 (E) 2 Contents Page Foreword ..............................................................................................................................................................3 Introduction .........................................................................................................................................................4 1 Scope ......................................................................................................................................................5 2 Terms and definitions ...........................................................................................................................5 3 Principle ..................................................................................................................................................9 4 Survey requirements .......................................................................................................................... 10 4.1 General ................................................................................................................................................. 10 4.2 Defining hydromorphological units .................................................................................................. 10 4.3 Survey strategy ................................................................................................................................... 10 4.4 Reference conditions ......................................................................................................................... 11 4.4.1 General ................................................................................................................................................. 11 4.4.2 Morphological and hydrological conditions .................................................................................... 11 5 Features for survey and assessment ............................................................................................... 12 5.1 Features and attributes ...................................................................................................................... 12 5.2 Pressures on hydromorphology ....................................................................................................... 12 5.2.1 General ................................................................................................................................................. 12 5.2.2 Classes of human pressures ............................................................................................................. 13 5.3 Data sources and methods of obtaining information ..................................................................... 16 6 Reporting hydromorphological assessment and classification .................................................... 17 6.1 General ................................................................................................................................................. 17 6.2 Data presentation................................................................................................................................ 17 7 Training and quality assurance for survey and assessment ......................................................... 18 7.1 General ................................................................................................................................................. 18 7.2 Areas for training ................................................................................................................................ 18 7.3 Data entry and validation ................................................................................................................... 19 Bibliography ..................................................................................................................................................... 20

SIST EN 16503:2014

EN 16503:2014 (E) 3 Foreword This document (EN 16503:2014) 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 February 2015 and conflicting national standards shall be withdrawn at the latest by February 2015. 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. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16503:2014

EN 16503:2014 (E) 4 Introduction Hydromorphology of transitional and coastal (TraC) waters is one of the basic features of marine and coastal ecosystems controlling the presence of biota. Hydromorphology is the result of the interaction between the structure of the systems and their functioning. Structure includes sea-bed geology, sediment features, morphology and water depth, whereas functioning includes hydrodynamics, sediment dynamics and morpho-dynamic processes. Over the past several millennia, human developments in TraC waters throughout Europe have caused substantial changes in the hydromorphological characteristics and ecological functioning of many water bodies. Hydromorphological changes are an important consideration in implementing the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). In addition, for the Habitats Directive there is a need to maintain certain ‘features’ in favourable condition, which has also given rise to a focus on hydromorphological assessments. In a general sense, transitional waters (e.g. estuaries, fjords, some lagoons) are neither fully open coastal systems nor enclosed or flowing freshwater areas. (for the WFD definition, see Clause 2). Their boundaries may be defined by hydromorphological features and discontinuities, by salinity, or by any other hydrographic feature (e.g. water depth and tidal regime). The term ‘coastal waters’ has been defined for various legal and political purposes (e.g. see Clause 2) but in this hydromorphological standard they are defined as waters characterized by coastal features and influenced by coastal processes. This European Standard: a) supports environmental and conservation agencies in meeting monitoring requirements of the WFD and MSFD; b) provides information supporting other environmental reporting requirements (e.g. in relation to biodiversity or environmental impact assessment); c) supports management and restoration initiatives; d) identifies and defines the main pressures affecting European TraC waters. Note that in this standard, “assessment” is used as a broad term referring to the general description of features and the pressures that impinge upon them. It is not used to imply the judgement of particular levels of “quality” or “value”, whether related to status under the WFD, MSFD or more generally. WARNING — Persons using this European Standard should be familiar with usual laboratory and fieldwork practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. IMPORTANT – It is absolutely essential that tests conducted according to this European Standard be carried out by suitably trained staff. SIST EN 16503:2014

EN 16503:2014 (E) 5 1 Scope This European Standard gives guidelines for characterizing the hydromorphology of transitional or coastal (TraC) waters, but does not prescribe detailed methods of assessment. The main aim of this document is to improve the comparability of hydromorphological survey methods, data processing, and the interpretation and presentation of results. This European Standard: a) lists essential features and processes of TraC waters that should be characterized as part of a hydromorphological survey and used for determining hydromorphological condition; b) gives guidance on strategies for collecting and presenting hydromorphological data depending on the resources available and the anticipated use of the assessment; c) describes how to generate data sets appropriate for monitoring and reporting on the condition of Natura 2000 sites designated under the Habitats Directive and the Birds Directive; d) provides guidance on data quality assurance. This European Standard does not deal with biological assessments in TraC waters such as the presence or absence of individual species or community composition, nor does it attempt to link specific hydromorphological features with their associated biological communities. However, it is relevant where plants or other organisms form significant structural elements of the habitat (e.g. saltmarshes, biogenic reefs). 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 aquatic macrophyte larger plant of marine and brackish water which is easily seen with the naked eye, including angiosperms and macroalgae EXAMPLE Examples for angiosperms: reeds, saltmarsh and seagrass beds; example for macroalgae: seaweed. [SOURCE: EN 16039:2011, 3.1, modified] 2.2 attribute specific recorded elements of a hydromorphological feature EXAMPLE ‘Silt’ and ‘boulders’ are natural substrate texture attributes, ‘sheet piling’ and ‘gabions’ are attributes of engineered banks. [SOURCE: EN 16039:2011, 3.2] 2.3 bay closing line straight line drawn between prominent physical features on either side of a bay SIST EN 16503:2014

EN 16503:2014 (E) 6 2.4 bedform pattern morphology of the seabed Note 1 to entry: The bedform patterns may be simple or complex depending on the size and shape of the system and the nature of the local sediment transport processes. Deposition produces features such as sand and gravel bars, while erosion results in scour features. 2.5 biogenic reef mass consisting of the hard parts of organisms, or of a biogenically constructed frame enclosing detrital particles, in a body of water Note 1 to entry: Most biogenic reefs are made of corals or associated organisms. 2.6 coastal cell length of coastline confined by natural or artificial barriers across which little or no sediment is transported 2.7 coastal plain estuary submerged coastal river valley 2.8 coastal water body of surface water on the landward side of a line, every point of which is at a distance of one nautical mile on the seaward side from the nearest point of the baseline from which the breadth of territorial waters is measured, extending where appropriate up to the outer limit of transitional waters Note 1 to entry: This definition from Article 2 of the EC Water Framework Directive (2000/60/EC) is one example of a definition of ‘coastal water’ used for legal purposes. 2.9 connectivity linkage within and between water bodies through exchange of water, sediment and organisms 2.10 ecological status expression of the quality of the structure and functioning of aquatic ecosystems, by comparing the prevailing conditions with reference conditions Note 1 to entry:

As classified in accordance with Annex V of the EC Water Framework Directive (2000/60/EC). [SOURCE: EN 16039:2011, 3.15] 2.11 fetch fetch length distance of open water over which the wind can blow and generate wind-driven waves [SOURCE: EN 16039:2011, 3.19, modified — “fetch length” was added as synonym] 2.12 fjord long narrow and glacially eroded inlet with steep sides, created in a valley often with a shallow entrance at the mouth SIST EN 16503:2014

EN 16503:2014 (E) 7 2.13 headland promontory of land projecting into water [SOURCE: EN 16039:2011, 3.20] 2.14 highest astronomical tide HAT highest tide that can be expected to occur under average meteorological conditions and at the spring and autumn equinox 2.15 hydromorphology physical, hydrological and hydrodynamic characteristics of transitional and coastal waters including the underlying processes from which they result [SOURCE: EN 16039:2011, 3.22, modified] 2.16 intertidal area foreshore zone between high and low tide lines 2.17 lagoon expanses of shallow coastal salt water, of varying salinity and water volume, wholly or partially separated from the sea by sand banks or shingle, or, less frequently, by rocks Note 1 to entry: The EC Water Framework Directive (2000/60/EC) classifies lagoons as ‘transitional waters’. 2.18 micro-tidal tidal range < 2 m 2.19 mixing blending of waters of different characteristics (e.g. temperature, turbidity, salinity) by turbulence and diffusion, caused by tides, winds, waves, currents and river runoff 2.20 normal tidal limit NTL point at which the level of a river or stream ceases to be affected by the tidal flow 2.21 physiography prominent coastal landform features 2.22 planform view of transitional or coastal water body from above EXAMPLE Sinuous, straight. 2.23 reef ridge of rock, or other material, lying seawards of the low water line SIST EN 16503:2014

EN 16503:2014 (E) 8 2.24 reference condition condition which is totally or nearly totally undisturbed by human activity 2.25 residence time retention time length of time it takes for a transitional water, sea loch or fjord to exchange its water Note 1 to entry: For enclosed bays “retention time” is the preferred term. 2.26 saltmarsh area having characteristic vegetation adapted to saline soils and to periodic inundation by sea water 2.27 sandbank low-energy feature created at the mouth of a river where it flows into the sea Note 1 to entry: Characteristic of the coast, often poorly defined. 2.28 storm surge change in water level as a result of meteorological forcing (wind, high or low barometric pressure) additional to the astronomic tide; it may be positive or negative 2.29 stratification layering of water column due to density differences resulting from changes in temperature, turbidity or salinity with depth 2.30 substrate rocky or sedimentary material making up the bed of a transitional or coastal water body 2.31 subtidal area zone seawards below the mean low tide line 2.32 tidal prism volume of water that flows into a tidal channel on the flood tide [SOURCE: EN ISO 772:2011, 2.49] 2.33 tidal range difference in level between high water and low water of a tide [SOURCE: EN ISO 772:2011, 2.50] 2.34 tidal regime parameters characterizing tides including levels, periods, frequencies, harmonics, phases and spectra SIST EN 16503:2014

EN 16503:2014 (E) 9 2.35 tidal bore tidal phenomenon in which the leading edge of the incoming tide forms a “wave” (or waves) of water that travel up a narrowing estuary or bay against the direction of the river or bay's current 2.36 topography bathymetry sea-bed level with reference to a given elevation 2.37 transitional water body of surface water in the vicinity of river mouths which is partly saline in character as a result of their proximity to coastal waters but which is substantially influenced by freshwater flows Note 1 to entry: In accordance with Article 2 of the EC Water Framework Directive (2000/60/EC). 2.38 turbidity reduction of transparency of a liquid caused by the presence of suspended particulate matter [SOURCE: ISO 6107-2:2006, 145] 2.39 wave exposure wave energy environment of a shoreline Note 1 to entry: An important variable, along with substrate composition and water depth, that influences the habitat characteristics of the shoreline. 2.40 wetland habitat occupying the transitional zone between permanently inundated, and generally dry, environments EXAMPLE Saltmarsh or wetland fed by groundwater. [SOURCE: EN 14614:2004, 3.42, modified] 3 Principle A standard protocol is described for recording the physical features of TraC waters. The range of features, and the methods used for survey, may vary according to the type of water body and the objectives of the study. This European Standard provides a general framework for these different methods, details of which can be found in the references cited in the Bibliography. It relies on a combination of measurements, models and expert judgement, which in turn will help to improve the current state of knowledge of this subject area. Guidance is given on the hydromorphological features that should be used for characterizing TraC water-body types and for further assessment of hydromorphological integrity through comparisons with reference conditions. The selection of features for survey will depend upon the type of pressures affecting the hydromorphology of a water body and the impacts they may cause, taking account of its particular hydromorphological context. SIST EN 16503:2014

EN 16503:2014 (E) 10 4 Survey requirements 4.1 General Survey design should record the water body’s hydromorphological form and function, the nature and location of pressures acting upon it, and provide an understanding of the likely impacts of those pressures. 4.2 Defining hydromorphological units It is necessary to determine the relevant spatial scales for assessment to support the planning of surveys and for describing reference conditions. Units for assessing TraC waters should be defined using morphological features, geographical units and discontinuities in coastlines, water column characteristics, coastal cells, inputs of fresh water, and dimensions. The aim should be to delimit manageable areas for hydromorphological assessment. Coastal waters may be dynamic and long-shore boundaries should be identified. These can be defined at various scales, depending on the purpose of the study. No one definition of the landward boundary of coastal waters accurately fits all conditions. Highest Astronomical Tide limit provides a consistent and definable landward boundary, although internationally recognized baselines are now used to delimit the start of territorial waters. In non-tidal or micro-tidal systems, a locally agreed high water mark, which allows for storm surges, will suffice. The seaward boundary of coastal waters is usually defined geo-politically based on distance from the accepted baselines – normally to the 12-mile limit although this has no scientific justification. For the purpose of hydromorphological assessment, the seaward limit along active shorelines in coastal waters is the boundary beyond which significant nearshore hydrodynamic changes (e.g. sediment transport) cannot be detected. For rocky coasts, where such processes are less significant, a more pragmatic seaward limit can be set, such as the 1 nautical mile boundary in the WFD. For hydromorphological assessments of transitional waters, a ‘whole estuary approach’ works well for small and medium-sized estuaries. In large estuaries, geological constraints combined with greater contrasts in wave energy dissipation can produce two or more distinctive ‘behavioural zones’ within the estuary. Transitional waters (except for non-tidal lagoons) where not constrained by artificial structures, often do not have clear boundaries with surrounding habitats. However, their boundaries need to be defined in a consistent way so that valid comparisons can be made. The upstream limit should be defined as the Normal Tidal Limit. The location of a boundary at the seaward limit of transitional waters should take account of the particular geography of each site. Often, geographical features such as deltaic sandbanks, narrow mouth entrances (e.g. lagoons), or discontinuities (breaks) in the coastline create a locally agreed boundary, hence the need for local expertise and agreement. In some areas and countries, consistency has been achieved using a ‘bay closing line’ across the mouth of an estuary although this is difficult to determine in wide-mouthed, funnel-shaped, coastal plain estuaries. 4.3 Survey strategy The hydromorphology of transitional and coastal waters is often very complex, reflecting a large number of forcing factors operating over different temporal and spatial scales. In order to develop meaningful survey and assessment strategies it is necessary, therefore, to establish a conceptual understanding of how these forces shape hydromorphology and how this may change over time. This understanding can then help in evaluating the likely significance of human pressures and in designing monitoring strategies. The scale of survey is important in hydromorphological assessment of TraC waters, especially with respect to resolution and connectivity, and in assessing the severity of impacts. Different survey techniques are scale-dependent. Different applications require different levels of detail. In some instances, survey may be extended beyond the hydromorphological units of interest to provide a complete picture of the relevant physical processes involved. SIST EN 16503:2014

EN 16503:2014 (E) 11 Timing and frequency of survey will vary among the different TraC waters because of their individual dynamic behaviour, and will depend upon the reason for assessment. Hydrodynamic attributes should generally be recorded at a higher frequency than morphological attributes. The timing of survey will depend upon the objectives of the work and the methods used. To measure certain conditions and regimes in continuously changing dynamic systems, measurements should be continuous or periodic according to the dominant daily, tidal, seasonal, lunar, annual or other cycles. The frequency of survey should ideally be linked with the rate of hydromorphological change; this in turn is partly related to the resistance to change and the resilience of the system to recover from a specific set of pressures. Other survey frequencies may be dictated by specific monitoring requirements. As a general rule, knowledge from all relevant sources and disciplines should be considered; networking and collaboration among experts and institutions at national and international levels will ensure consistency across broad scales, help to harmonize monitoring, and increase understanding of the hydromorphological functioning of TraC water bodies. 4.4 Reference conditions 4.4.1 General The identification of hydromorphological reference conditions is an essential pre-requisite for assessing the condition, or degree, of hydromorphological modification present in TraC waters. Reference conditions should be identified within each type of TraC water (taking account of natural changes) reflecting conditions that are totally, or nearly totally, undisturbed by human activities. In this context, scale is important in considering human effects on hydromorphological modifications. These reference conditions may be identified where undisturbed sites still exist, but also by combining expert judgement with modelling or by using historical data. In most cases reference conditions will not constitute the target for restoration or for assessing the environmental impact of particular developments. Instead, achievable restoration targets based on present hydromorphological conditions, should be defined using the guidance in this standard on which features to assess and on a strategy for their survey. 4.4.2 Morphological and hydrological conditions 4.4.2.1 Basic requirements

In reference condition, variations of the following attributes should be within the envelope of natural variability (either observed or modelled) and consistent with natural dynamic processes. In addition, connectivity should be maintained to avoid disrupting processes. 4.4.2.2 Hydrodynamic regime

Hydrographic attributes such as tides, currents and waves, salinity, temperature, stratification and mixing processes, fronts, etc. match with the characteristics of the particular hydromorphological units (or sub-areas of TraC waters). 4.4.2.3 Bedform patterns, substrates and morphodynamics

These attributes correspond to conditions that are controlled by the natural hydrodynamic regime or the subsurface geology of the hydromorphological units. Changes in bedform patterns, substrates and morphodynamics minimally alter the characteristics of the hydromorphological unit. Along active coastlines subject to water level changes (e.g. by tides) the spatial distribution of submerged and exposed areas is minimally altered. 4.4.2.4 Hydromorphological connectivity

There are no structural impediments or significant abstraction or discharge pressures that prevent natural sediment transport and exchange with surface waters. SIST EN 16503:2014

EN 16503:2014 (E) 12 5 Features for survey and assessment 5.1 Features and attributes Table 1 sets out the principal feature categories for hydromorphological assessment of TraC waters. However, some hydromorphological processes or features do not occur in all types of coastal systems or parts of systems. Thus, areas for hydromorphological assessment should accord with natural coastal processes and coastal cells. Characteristics should be selected that are relevant to the water-body type or category, e.g. tidal regime is less relevant for the Baltic Sea, density regime is less relevant for coastal lagoons, etc. Table 1 — Hydromorphological characteristics of transitional and coastal waters Assessment Categories No. Generic features Examples of attributes assessed Morphology 1 Physiography/ Depth/Elevation Topography, bedforms, mouth width, intertidal area: subtidal area ratio; tidal volume; linear coastlines, beach types, artificial structures 2 Connectivity Presence of adjoining physical features and links within and between water bodies, and between TraC waters and wetlands; mouth width, presence of artificial structures (e.g. dams) 3 Geology Substrate type, bedform patterns 4 Biogenic structures Presence of aquatic macrophytes and biogenic reefs Hydrodynamic regime 5 Tidal regime, water level and current Current velocity and direction, water level variability, tidal range, tidal prism, presence of tidal bore 6 Wave regime Exposure, wind speed and direction, fetch, wave height 7 Freshwater inputs and runoff Residence time/flushing rate (transitional waters), retention time (enclosed bays), freshwater discharge 8 Sediment dynamics Sediment supply, erosion/ deposition/ transport cycles 9 Stratification or degree of mixing Salinity, turbidity, density, temperature 5.2 Pressures on hydromorphology 5.2.1 General The extent to which a human-induced pressure will affect the physical structure and functioning of TraC waters depends on a number of variables which might include one or more of the following: — type of operation or activity; — spatial scale, duration and frequency of operation or activity; — hydrodynamic conditions (e.g. tidal range, current velocities); SIST EN 16503:2014

EN 16503:2014 (E) 13 — coastal landforms; — substrate type, sediment characteristics (e.g. particle size), bedform patterns; — seasona

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