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Title: A Review of Methods for Assessing the Hydromorphology of Lakes
Author: O.M. Bragg
Author: R.W. Duck
Author: J.S. Rowan
Author: A.R. Black
Author: SNIFFER
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1335, Representation ID: 441, Object ID: 2511
Abstract:
...................................................................................................................... 1 1. BACKGROUND ............................................................................................................................... 4 1.1 Lakes: their definition, origins and importance ........................................................................... 4 1.2 Morphology and hydrology of lakes............................................................................................ 6 1.3 The Water Framework Directive................................................................................................. 9 2. OBJECTIVES ................................................................................................................................ 11 3. HYDROMORPHOLOGICAL PRESSURES AND IMPACTS......................................................... 12 3.1 Potential pressures and hydromorphological changes............................................................. 12 3.2 Evidence for pressures and hydromorphological changes....................................................... 13 3.2.1 Introduction ......................................................................................................................... 13 3.2.2 Catchment land uses ......................................................................................................... 13 3.2.3 Water abstraction............................................................................................................... 15 3.2.4 Construction of dams and barrages................................................................................... 17 3.2.4.1 Changes in water level ................................................................................................. 18 3.2.4.2 Changes in patterns of water level fluctuations........................................................... 19 3.2.4.3 Changes in rate of throughflow ................................................................................... 24 3.2.4.4 Effects on sediment dynamics..................................................................................... 25 3.2.5 Shoreline modification ....................................................................................................... 26 3.3 Overview of pressures and hydromorphological changes........................................................ 27 4. ASSESSMENT METHODS FOR LAKE HYDROMORPHOLOGY ................................................ 29 4.1 Introduction............................................................................................................................... 29 4.2 Hydrographic survey ................................................................................................................ 29 4.3 Predictive limnology ................................................................................................................. 35 4.4 Quantity and structure of the substrate ..................................................................................... 39 4.5 Water level ................................................................................................................................ 42 4.6 Structure and condition of the shore zone................................................................................. 46 4.7 Quantity and dynamics of flow .................................................................................................. 50 4.8 Residence time.......................................................................................................................... 53 4.9 Connection to groundwaters ..................................................................................................... 56 4.10 Habitat measurement .............................................................................................................. 60 4.11 Overview of methods for WFD hydromorphological quality elements .................................... 63 5. EVALUATION OF METHODS FOR WFD PURPOSES ................................................................ 65 5.1 Introduction............................................................................................................................... 65 5.2 Typology and reference conditions........................................................................................... 66 WFD06 i 5.2.1 Rationale............................................................................................................................ 66 5.2.2 Existing approaches .......................................................................................................... 68 5.2.3 Towards a UK typology for lakes ....................................................................................... 74 5.3 Pressures and impacts ............................................................................................................. 77 5.3.1 Rationale........................................................................................................................... 77 5.3.2 Identification of pressures ................................................................................................... 77 5.3.3 The association between pressures and hydromorphological impacts.............................. 79 5.3.4 Assessment of impacts ....................................................................................................... 82 5.3.4.1 Hydrological regime (quantity and dynamics of flow and water level).......................... 82 5.3.4.2 System sensitivity to water level changes .................................................................... 83 5.3.4.3 Sensitivity to changes in groundwater status .............................................................. 87 5.3.4.4 Assessment of changes in depth variation................................................................... 87 5.3.4.5 Assessment of changes in quantity and structure of the substrate ............................. 88 5.3.4.6 Residence time ............................................................................................................ 88 5.3.4.7 Structure and condition of the shore zone................................................................... 89 5.3.4.8 Heavily Modified Water Bodies ................................................................................... 96 5.3.4.9 Summary of methods for impact assessmemt .......................................................... 100 5.4 Monitoring and management.................................................................................................. 102 5.4.1 Rationale........................................................................................................................... 102 5.4.2 Objectives of monitoring .................................................................................................. 102 5.4.3 Existing approaches to monitoring of lakes ..................................................................... 103 5.4.4 Principles of monitoring for the WFD .............................................................................. 104 5.4.5 Surveillance monitoring of lake hydromorphology ........................................................... 105 5.4.5 Operational and investigative monitoring ........................................................................ 105 6. RESEARCH NEEDS ................................................................................................................... 109 6.1 Typology ................................................................................................................................. 109 6.2 Data sources for assessment of pressures ............................................................................. 110 6.3 Use of remote sensing in site assessment .............................................................................. 112 6.4 Towards the development of an abiotic screening tool for lakes............................................. 112 7. SUMMARY AND CONCLUSIONS .............................................................................................. 114 8. ACKNOWLEDGEMENTS............................................................................................................. 116 9. REFERENCES ............................................................................................................................ 117 ANNEX 1 Literature search methods ............................................................................................... 130 WFD06 ii LIST OF TABLES Table 1 Classification of lake types (after Hutchinson 1957). .............................................................. 5 Table 2 Pressures and potential impacts on river hydromorphology. ................................................ 12 Table 3 Summary of human pressures on lakes, and the resulting impacts on hydromorphology and biota. ............................................................................................................................................ 27 Table 4 Summary of effects of damming on lake hydromorphology and biota. ................................. 28 Table 5 Terminology, class limits and probability of occurrence of the various lake forms, modified from HAkanson (1981). ................................................................................................................ 32 Table 6 Morphometric information that can be derived from bathymetric charts, after HAkanson (1981). ......................................................................................................................................... 33 Table 7 Definitions and formulae for lake morphometric parameters, after HAkanson (1997)........... 38 Table 8 Field investigation methods used in the Lake Pontchartrain Basin study, from Manheim and Hayes (2002). .............................................................................................................................. 41 Table 9 Types of physical evidence that may indicate historical changes in lake level, after Duck et al. (1998)...................................................................................................................................... 46 Table 10 Summary of RHS survey data (after Fox et al. 1998) ......................................................... 47 Table 11 Rules for derivation of the Habitat Modification Score (HMS) from RHS data. ................... 49 Table 12: Catchment areas, long average annual precipitation and evapotranspiration, average runoff, basin volumes and average residence times of Lochs Butterstone, Marlee, Earn and Tummel (Duck 1982). .................................................................................................................. 54 Table 13 Instantaneous residence for Lough Inchiquin, Co. Clare, after Allott (1990)....................... 55 Table 14 Catchment and basin habitat measurement and metrics (USEPA 1998). .......................... 61 Table 15 Physical and chemical measurements and metrics (USEPA 1998).................................... 61 Table 16 Lakeshore habitat measurements and metrics (USEPA 1998)........................................... 62 Table 17 Summary of methods for measuring hydrological quality elements of lakes. ..................... 63 Table 18 Summary of methods for measuring morphological quality elements of lakes. ................... 64 Table 19 Outline of aSystem Aa and aSystem Ba typology systems for lakes (WFD Annex II). .......... 67 Table 20 Schematic Type A classification of lakes in Great Britain. .................................................. 68 Table 21 Proposed typological schemes and categories for Ireland and Austria .............................. 69 Table 22 Description of the six diatom groups identified by Bennion et al. (undated) according to physical descriptors. .................................................................................................................... 70 Table 23 List of Scottish lochs where biological data are being collected. Source: J. Tuck. ............ 71 Table 24 Classification of standing waters in Britain (after Palmer et al. 1992). ................................ 73 Table 25 Summary of variables identified as significant at primary and secondary level in each of the classifications of New Zealand rivers........................................................................................... 73 Table 26 Non-biological data required to form the basis of lake classification................................... 76 Table 27 Evidence of human pressures on lakes (Herlihy, 1997)...................................................... 77 WFD06 iii Table 28 Information that is relevant to assessment of pressures on the WFD hydromorphological quality elements for lakes, with potential sources........................................................................ 78 Table 29 Human pressures in lake catchments, the associated activities, and their potential impacts on hydromorphological conditions. .............................................................................................. 79 Table 30 Human pressures within lake basins, and the associated risks and potential impacts on hydromorphological conditions. ................................................................................................... 81 Table 31 Ranking of Cumbrian lakes according to their sensitivity to water level drawdown, assessed on the basis of 25% exposure depth. .......................................................................................... 85 Table 32 Physical features of likely significance for determining hydromorphological condition in terms of degree of habitat modification and overall status aHabitat Qualitya and aHabitat Modificationa in a proposed Lake Habitat Survey scheme ........................................................... 94 Table 33 Proposed scheme to develop an Abiotic Index employing both hydrological regime change and morphological alteration........................................................................................................ 95 Table 34 Changes in area and perimeter of the eight reservoir water bodies of the Tummel catchment due to impoundment. Derived by GIS (ArcGIS 8.1) analysis of the digital data used to construct Figure 18...................................................................................................................................... 99 Table 35 Some hydromorphological characteristics of the Tummel reservoirs.................................. 99 Table 36 Physical characteristics of the shore zones of four Tummel reservoirs (bold type) and five natural Scottish lochs observed during the week 14-18 July 1980. From Smith et al. (1987). . 100 Table 37 Summary of methods for hydromorphological impact assessment that are appropriate to WFD implementation. ................................................................................................................ 101 Table 38 Monitoring hydromorphological quality elements in Irish lakes: summary table. After Irvine et al. (2002)................................................................................................................................ 104 Table 39 Suggested scheme for surveillance monitoring of lakes. .................................................. 106 Table 40 Associations between impairment of biological quality and hydromorphological impacts reported in the literature*. .......................................................................................................... 108 Table 41 Input data (variables) required to determine hydromorphological quality elements........... 109 Table 42 Inter-relationships between System B candidate variables and hydromorphological quality elements .................................................................................................................................... 110 Table 43 Information that is relevant to assessment of pressures on the WFD hydromorphological quality elements for lakes, with potential sources...................................................................... 111 WFD06 iv LIST OF FIGURES Figure 1 The major habitats found in a typical lake. From Maitland (1990). ....................................... 6 Figure 2 A schematic representation of the main differences between eutrophic (left) and oligotrophic (right) lakes. From Maitland (1990)................................................................................................ 7 Figure 3 The annual thermal cycle of a typical deep lake in the temperate zone. From Duck (1982). 8 Figure 4 Relationships between contour area and depth (hypsographic curves) for Haweswater in the English Lake District, representing the natural basin (broken blue line) and the basin after dam construction (solid red line). Data from Ramsbottom (1976). ............................................. 19 Figure 5 Comparison of annual hydrographs for Loch Quoich, Scotland, for 1933 (before damming for hydro-power generation) and 1993. ....................................................................................... 23 Figure 6 Comparison of annual hydrographs for Loch Oich, Scotland, for 1931 (before hydro-power generation) and 1991................................................................................................................... 24 Figure 7 Schematic bathymetrical interpretation of four statistical lake forms, from HAkanson (1981). ..................................................................................................................................................... 31 Figure 8 Terminology and class limits for the classification system of lake forms, from HAkanson (1981). ......................................................................................................................................... 32 Figure 9 Map of HAkansonas Form Roughness (Rf) for Loch Muick, from Lowe (1993). ................... 35 Figure 10 Some hydromorphological relationships derived by Gorham (1958) from the bathymetric data of Murray and Pullar (1910). ................................................................................................ 36 Figure 11 Comparison of water level duration curves for Loch Quoich, Scotland, for 1933 (before damming for hydro-power generation) and 1993. Water level records for the two years are not related to the same datum level................................................................................................... 43 Figure 12 Comparison of water level duration curves for Loch Oich, Scotland, for 1931 (before the catchment was used for hydro-power generation) and 1991. Datums have been adjusted so that 50%ile values coincide. ............................................................................................................... 44 Figure 13 Ordination of 35 British and Irish lakes, from Allott (1990)................................................. 52 Figure 14 Basic configurations of groundwater flow systems around lakes, from Vanek (1985)....... 57 Figure 15 A typical vertical-section model showing the seepage pattern at the margin of a lake, from Vanek (1985). .............................................................................................................................. 58 Figure 16 Representation of a lake comprising two basins with significantly different morphological (and ecological) characteristics. From Wallin et al. (2002). ........................................................ 75 Figure 17 Percentage hypsographic curves for 12 lakes in Cumbria, England, derived from data given by Ramsbottom (1976)....................................................................................................... 86 Figure 18 Comparison of relative hypsographic curves (lake form) for Haweswater before and after impoundment. The same data are plotted in depth-area form in Figure 4.................................. 88 Figure 19 Sketch map showing the dimensions of observation plot at each station of the EMAP scheme. ....................................................................................................................................... 90 WFD06 v Figure 20 Physical habitat sketch map produced during EMAP field survey. .................................... 91 Figure 21 Sample of field recording form used in the EMAP habitat assessment, page one. ........... 92 Figure 22 Sample of field recording form used in the EMAP habitat assessment, page two............. 93 Figure 23 Steps leading to the provisional identification of HMWB. From CIS (2002)....................... 96 Figure 24 Comparisons of the present shapes of the Tummel hydro-power reservoirs (blue) with their shapes before closure of the dams (stippled). ............................................................................. 98 WFD06 vi EXECUTIVE SUMMARY Review of methods for assessing the hydromorphology of lakes WFD06 June 2003 The European Water Framework Directive (WFD) was adopted on 22 December 2000. This is a major legislative initiative, intended to resolve the piecemeal approach to European water law which has developed since 1975. The WFD stipulates that surface water bodies such as lakes should achieve good ecological and chemical status (pollutant levels) by 2015. Good ecological status requires hydromorphological conditions supporting at worst aslight changesa in the composition and abundance of key biological quality elements (phytoplankton, macrophytes and phytobenthos, benthic macroinvertebrates and fish fauna) relative to the appropriate natural reference condition (high ecological status). The two elements of hydromorphology are hydrological regime and morphological conditions, the corresponding hydromorphological quality elements are: Hydrological regime: quantity and dynamics of flow, level, residence time, and the resultant connection to groundwaters reflect totally or nearly totally undisturbed conditions. Morphological conditions: lake depth variation, quantity and structure of the substrate, and both the structure and condition of the lake shore zone, correspond totally or nearly totally to undisturbed conditions. Standing waters designated as Heavily Modified Water Bodies (HMWBs) or Artificial Water Bodies are required to attain Good Ecological Potential by 2015. Currently no EU Member States carry out routine assessments of lake hydromorphology. A comprehensive literature review has provided an overview of human pressures on lakes, and the resulting impacts on hydromorphology and biota. A review of methods used to measure the hydromorphological quality attributes of lakes has identified several potential metrics for each. Methods vary in the ease with which they can be adapted for the purposes of the Directive. Member states are required to produce a lake typology based on a modelling and/or a reference network of undisturbed water bodies (including development of hydromorphological reference conditions) that define high ecological status. The System A typology is unlikely to prove adequate for UK purposes. A priority need is therefore the development of a UKWFD06 1 specific System B typology, ideally using statistical clustering to determine the most significant optional factors (additional hydrological quality elements) to be to be included beyond the System A obligatory factors. A key milestone in the implementation of the WFD is by 2004 to complete a screening exercise to identify significant pressures acting on water bodies and identify those at risk of failing to achieve good ecological status (inclusive of rivers, lakes, transitional and coastal waters). Many of the pressures operating in the catchment of an individual lake can be assessed by direct observation. However, the scale of the exercise required for WFD implementation is such that it will be expedient to use desk-based information sources as far as possible. An outline scheme is presented, which should take advantage of existing databases, exploiting where possible Geographical Information Systems (GIS) query techniques. An important conclusion emerging from the review exercise is that both the quantity and quality of existing aquatic ecology data sets are limited. Clearly the regulatory authorities (e.g. the Scottish Environment Protection Agency or the Environment Agency in England and Wales) need to initiate new measurement and monitoring campaigns. There are also fundamental gaps in the knowledge base regarding the inter-relationships between ecology and hydromorphology. In the absence of fuller ecological data sets, more emphasis must be placed on abiotic approaches to both screening and in guiding the necessary programmes of measures needed to raise a failing water body to at least good ecological status. A screening tool is proposed in the form an Abiotic Index based on a combination of the Dundee Hydrological Regime Alteration Method (DHRAM) for standing waters and a newly proposed Lake Habitat Survey (LHS) approach derived from the integration of the Environment Agencyas River Habitat Survey (RHS) and the USEPAas Field Operations Manual for Lakes (FOML). Extensive field-testing is required to calibrate such screening tools with ecological data, not only to validate the underlying science, but to ensure that designations and management options are accepted by all stakeholders and user groups. In addition to initiating a surveillance (monitoring) exercises, it will be necessary to implement a Programme of Measures to ensure that the hydromorphological quality elements of a standing water body such as a lake are improved to enable the biota to achieve the requirements of good ecological status or good ecological potential in the case of HMWBs. A series of recommendations are made accordingly. WFD06 2
Publisher: Environment Agency
Subject Keywords: Water quality; Monitoring; Lake; River habitat survey; Wfd; Pressure; Assessment; Water bodies; Hyromorphological impacts; Hydromorphological; Field survey techniques; Remote methods; Ecological assessment methods; Quantity and dynamic flow; Water frameword directive
Extent: 138
Permalink: http://www.environmentdata.org/archive/ealit:4692
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