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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
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1335, Representation ID: 441, Object ID: 2511
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 ‘slight changes’ 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: 1. Hydrological regime: quantity and dynamics of flow, level, residence time, and the resultant connection to groundwaters reflect totally or nearly totally undisturbed conditions. 2. 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. 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. 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 Agency’s River Habitat Survey (RHS) and the USEPA’s 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.
Publisher: Environment Agency
Subject Keywords: Water qualityLakesRiver habitat surveyWater Framework DirectivePressureMorphologyMonitoringMethodologyFreshwater ecologySurvey methods
Extent: 138
Total file downloads: 379

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