Hydro-morphology, simply put this means SEPA has to monitor and assess pressures/impacts on:
- Hydrological regime (quantity and dynamics of flow, connection to groundwater)
- Continuity (ability of sediment and migratory species to pass freely up/down rivers and laterally with the floodplain)
- Morphology (i.e. physical habitat – compositions of substrate, width/depth variation, structure of bed, banks and riparian zone, planform)
The ecological classification system required under the Water Framework Directive describes hydromorphological elements as ‘supporting the biological elements’. Each of the four surface water categories – rivers, lakes, transitional waters and coastal waters – are ascribed specific hydromorphological quality elements (Annex V). However, unlike the biological elements (e.g. for fresh waters: phytoplankton, macrophytes and phytobenthos, benthic invertebrates and fish) hydromorphological elements contribute to status classification only for water bodies at high ecological status (Annex V, 1.2). At good and at moderate ecological status, hydromorphological conditions are not defined but are to be ‘consistent with the achievement of the values specified …… for the biological quality elements.’ The morphological quality elements listed in Annex V are given in Table 1.
Table 1: Morphological attributes for each of the four surface water categories in the Water Framework Directive
Rivers
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River depth and width variation
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Structure and substrate of the river bed
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Structure of the riparian zone
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River Continuity
|
Lakes
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Lake depth variation
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Quantity, structure and substrate of the lake bed
|
Structure of the lake shore
|
Transitional Waters
|
Depth variation
|
Quantity, structure and substrate of the bed
|
Structure of the intertidal zone
|
Coastal Waters
|
Depth variation
|
Structure and substrate of the coastal bed
|
Structure of the intertidal zone
|
Surface water morphology is important not only for defining water bodies at high status, or for investigating possible reasons for water bodies that fail to reach good ecological status, it also has an important role to play in characterising and setting in place appropriate monitoring of ‘heavily modified’ and ‘artificial’ water bodies.
Heavily Modified and Artificial Water Bodies
Heavily Modified Water Bodies (HMWB) are bodies of water which as a result of physical alterations by human activity are substantially changed in character and cannot, therefore, meet the ‘good ecological status’. In this context:
- physical alterations mean changes to the hydromorphological characteristics of a water body, and
- a water body that is substantially changed in character is one that has been subject to major long-term changes in its hydromorphology as a consequence of maintaining the specified uses/human activities. In general these hydromorphological changes alter morphological and hydrological characteristics.
Relevant human activities are defined as navigation (including port facilities, or recreation), activities for the purposes of which water is stored (such as drinking-water supply, power generation or irrigation), water regulation, flood protection, land drainage, and other important sustainable human development activities.
Member States may identify these surface water bodies as provisional HMWB’s – this is a required part of the characterisation process.
Member States may designate surface water bodies as HMWB/AWB where they have been physically altered so that they are “substantially changed in character” or "created by human activity", subject to the tests specified in Article 4(3). The first test requires that the specified uses of the water body (i.e. navigation, hydropower, water supply or flood defence) or the ‘wider environment’ would be significantly adversely affected by the restoration measures required to achieve good ecological status.
The second test requires that there are no significantly better environmental options for delivering the specified use that are technically feasible and cost effective.
The designation of HMWB and Artificial Water Bodies (AWB) is optional; Member States do not have to designate water bodies as HMWB or AWB.
Instead of good ecological status, the environmental objective for HMWB/AWB is good ecological potential, which has to be achieved by 2015. The designation is not an opportunity to avoid achieving demanding ecological and chemical objectives, since good ecological potential is an ecological objective which may often, in itself, be challenging to achieve.
Artificial Water Bodies (AWB)
An artificial water body is a surface water body which has been created in a location where no water body existed before and which has not been created by the direct physical alteration or movement or realignment of an existing water body. This does not mean that there was only dry land present before. There may have been minor ponds, tributaries or ditches, which were not regarded as a discrete and significant element of surface water and therefore not identified as a water body.
Monitoring and assessment of hydromorphology under the Directive
There are a series of requirements under the Directive which will require Member States to monitor and assess the required hydromorphological quality elements:
- the assessment of pressures and impacts on the morphology of surface waters
- the restoration and monitoring of those waters significantly impacted by morphological alterations
- requirements for the regulation of future engineering activities
- the identification and designation of Heavily Modified Water bodies and Artificial Water bodies
- river basin management planning - setting of realistic environmental objectives whilst in balance with important socio-economic activities and industry (flood defence and management, navigation, hydro-electricity etc.).
