ABSTRACT1. In the absence of a standard procedure for characterizing the physical habitat of lakes in Europe, this paper describes the development of a multi-purpose Lake Habitat Survey (LHS). The technique has been designed to meet the hydromorphological assessment needs of the Water Framework Directive (WFD), as well as to assist in monitoring the condition of designated sites in the UK and for wider application in environmental impact assessments and restoration programmes.2. LHS involves detailed recording of shoreline features at a number of plots (Hab-Plots), complemented by a meso-scale survey of the entire lake, including shoreline characteristics and pressures, and modifications to the hydrological regime. A temperature and dissolved oxygen profile is also compiled at the deepest point of the lake (Index Site). Existing databases are exploited where possible, and remote sensing data (e.g. aerial photographs) are used to assist field-based observations.3. Initial field trials demonstrated that the consistency of the method, whether conducted by boat or on foot, was high. More than 250 surveys were carried out across the UK in 2004 through collaboration with the statutory environment and conservation agencies.4. Two levels of complexity were tested } a full version requiring 10 Hab-Plots and an abridged version, LHS core , involving four plots and omitting the Index Site. While 8-10 plots were required to capture the full diversity of features at complex sites, LHS core data were sufficient to generate metrics for classification purposes.5. A Lake Habitat Modification Score (LHMS) may be calculated from LHS data. This synthesizes a wide array of hydromorphological and human pressures and has direct applications for assessment of ecological status under the WFD. Preliminary analysis illustrates a spectrum of hydromorphological alteration of 82 lakes in the UK.6. Further considerations are discussed, including the prospect that the LHS protocol might form the basis of a European standard developed through CEN (Comite´Europe´en de Normalisation).

ABSTRACT1. A method has been developed for assessing the degree of human alteration of river flow regimes relative to near-natural or reference conditions.2. The Dundee Hydrological Regime Alteration Method (DHRAM) utilizes the Indicators of Hydrologic Alteration approach of the US Nature Conservancy to classify the risk of damage to instream ecology using a five-class scheme compatible with the requirements of the EC Water Framework Directive.3. Separate methods have been developed for rivers and lakes, though only the former are considered in this paper.4. DHRAM uses daily mean flow time-series data, representing un-impacted and impacted situations for the site of interest, in relation to any type of anthropogenic hydrological impact such as impoundments, abstractions or flow augmentation.5. Procedures for coping with different levels of data availability are outlined, utilizing the Micro Low Flows computer package to generate synthetic series of daily mean flows, supplemented by flow alteration data as appropriate.6. The utility of DHRAM is demonstrated through a pair of Scottish case studies illustrating its ability in classifying regime alteration and supporting mapping, which will be of value to river basin managers.7. Finally, present and future issues relating to the calibration of DHRAM scores to levels of ecological damage are discussed.

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Measurements made on the floors of the temporarilydrained Glenfarg and Glenquey Reservoirs indicate that sediments with wet volumes of 63.94 x lo3 m3 and 1264 x lo3 m 3 were deposited in 56 and 73 years respectively. These figures represent 2.5 per cent and 1.1 per cent losses of original storage capacity. When corrected for water, organic, and diatom skeleton contents,and reservoir trap efficiency inorganic sediment yields of at least 31.3 tonnes km-2yr-1 and of 9.0 tonnes km-2yr-1 are suggested. The difference is probably related to contrasts of land use.

New European legislation known as the Water Framework Directive (WFD) challenges catchment hydrologists and freshwater biologists to quantify the risk of damage to the organic communities of rivers that arises from anthropogenic distortion of the natural flow regime. Here, we take the first step towards this goal by collecting together relevant information from the two disciplines. An extensive biological literature is examined for insights into the ways in which the species and communities associated with rivers might change when the flow regime is altered. From the hydrological literature, the indicators of flow regime and flow regime change that are pertinent to ecology are described, and consideration is given to means of deriving flow regime data for ungauged river reaches. Attempts to combine hydrology and ecology in classifying rivers and in setting flow objectives to favour biota are then reviewed, together with integrated approaches to river management that aim to promote ecological quality. A significant scale disparity is noted between the disciplines, hydrology being studied at catchment, subcatchment and reach scales, and biology generally at local level. Nonetheless, both yield methods with potential applications in aspects of WFD implementation. The approach with most appeal for general risk assessment is based on the concept of hydrological alteration. This technique employs flow regime variables selected for their importance to aquatic and riparian ecology, and quantifies deviations from the natural values of these variables at reach scale. For WFD purposes, calibration of the scale of hydrological alteration in terms of risk to ecological status is desirable. In this, priority should be given to identification of the level of hydrological alteration that corresponds to the division between good and moderate ecological status.

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The natural evolution of the estuary-coastal lagoon system of the Ria de Aveiro, Portugal, was halted in 1808 by the construction of a new inlet/outlet channel through the sand spit which isolates it from the Atlantic Ocean. In consequence, tidal amplitudes in the lagoon increased from 0.07-0.13 m to over 1 m. Improvements to the channel since 1936, including construction of jetties, breakwaters and dredging, have increased its cross-sectional area. This has caused a steady increase in tidal amplitude to between 2.5 and 2.8 m, the erosion of mud flats, salt marsh and old salt pans, the widening and deepening of channels, and a greater capacity for sediment transport and dispersal due to the increased tidal currents. The volume of the tidal prism calculated for spring tides is now 1.7 times that in 1951; thus areas bordering the lagoon, especially agricultural fields, are experiencing a progressively increasing risk of flooding and salt water contamination at high water. Any future increase of mean sea level will contribute to an increase of both area and volume of the water mass and could cause important changes to the dynamics of the system. An increase in mean sea level of 0.1 m will, for example, correspond to an increase of 5% in the capacity of the system and contribute to an increase in the speed of tidal propagation. The resulting increase in the volume of the tidal prism will be up to 22% of the present maximum value. KEY WORDS: Coastal lagoon · Tidal changes · Morphological evolution · Sea level rise · Ria de AveiroResale or republication not permitted without written consent of the publisher