Hydrographical conditions

Physical and chemical features can be changed as a consequence of different patterns of human activities and the impacts of climate change. Large-scale human activities in coastal areas, on land and offshore such as coastal defence works, damming of large rivers, land reclamation projects, offshore infrastructure (bridges, airports),  offshore wind farms and other ocean energy device arrays and large-scale aquaculture facilities may permanently influence the hydrographical regime of currents, waves and sediments.

In addition, there are also smaller-scale activities that affect hydrographical conditions, such as local changes in salinity and temperature derived from discharges at sea of brines and refrigeration water. Potentially these structures in coastal or open sea could significantly affect entire regional seas such as the Baltic Sea, Black Sea and Mediterranean Sea.

Hydrographical conditions describe basic physical features of the water bodies and include bathymetry of the seabed, sea level, temperature, salinity, currents, tides, waves and turbidity. Physical and chemical features such as upwelling, wave exposure, mixing characteristics, turbidity, residence times, spatial and temporal distribution of nutrients, oxygen and acidification are also often used in this context to capture the dynamic nature of marine ecosystems and their natural variability.

Many of the human activities take place in coastal waters or on land (damming of rivers), therefore assessment and management of these aspects depends also on river basin management plans under Water Framework Directive (WFD; EC, 2000). Cumulative impact assessment should be considered for assessing the significance of the aggregated effects of hydrographical changes caused by human activities at sea and on land especially in the planning phase of new activities and in the Blue Growth and  Maritime Spatial Planning process (MSP; EC, 2014a; EC 2019).

In relation to 'Hydrographic conditions', the Marine Strategy Framework Directive considers that 'good environmental status' is achieved when ‘Permanent alteration of hydrographical conditions does not adversely affect marine ecosystems'.

Alterations of hydrographic conditions are likely to increase in the future due to climate change and due to plans for Blue Growth in coastal areas as well as offshore. Modelling studies (e.g. scenarios with and without the constructions and development) could help identifying pressures and potential impacts as well as establishing close links with the effects on the ecosystem. Large scale environmental impact assessments of cumulative pressures and their effects analysis of human activities including pressures from global changes should be used to predict the effects of increased human activities on the marine ecosystem in the future to support sustainable planning instead of local Environmental Impacts Assessments that are funded by single sectors.

General outcomes from the regional assessments

In the OSPAR maritime area, monitoring of basic physical and chemical characteristics is include temperature, sea ice, sea level, salinity, storms and waves, and ocean pH in reference to climate change. Relevant elements are not directly linked to alterations of hydrographic conditions caused by human activities. Offshore installations are abundant in particular in the North Sea, major developments in the oil and gas industry have resulted in a 1350 of offshore installations at present, most of them sub-sea steel installations and fixed steel installations (OSPAR- Offshore Installations) . Energy production by marine renewables has emerged in last decades in the coastal and shallower offshore waters of the OSPAR area, being driven by demands for increased renewable energy production as a result of policies to reduce reliance on fossil fuels and to mitigate the effects of climate change. The EU is committed to having 20% of its energy production from renewable sources by 2020 (OSPAR- Renewable). OSPAR has developed guidance on environmental considerations for the development of offshore wind farms. This recommends best practices to assess, minimise and manage the potential impacts of wind farms. The guidance also refers to hydrographic conditions, explicitly to disturbances of sedimentary or hydrodynamic processes that should not have significant impacts (OSPAR- Offshore Renewables)

The monitoring of hydrography covers the physical oceanographic parameters temperature, salinity, turbidity and water transparency, waves, currents and sea ice extent and thickness mainly to track changes in natural variability, eutrophication (water transparency) and to climate change. The link to changes of these parameters related to offshore and coastal constructions and of changes in riverine inflows is not addressed (HELCOM,  Hydrography)

Hydrographic conditions in the Black Sea are not assessed in the view of impacts from coastal constructions and offshore installations. Long-term, seasonal hydrographs of river runoff into the Black Sea for 1958-2017 are analysed.

Alterations of hydrographic conditions in the Mediterranean is addressed under ecological objective EO7 Hydrography with objective: alteration of hydrographic conditions does not adversely affect coastal and marine ecosystems. Common Indicator 15: Location and extent of the habitats impacted directly by hydrographic alterations.

Ecological Objective EO 8 Coastal ecosystems and landscapes addresses the natural dynamics of coastal areas with and indicator: Length of coastline subject to physical disturbance due to the influence of man-made structures. Off-shore developments are not addressed. The main knowledge gaps are related to insufficient surveys and monitoring of this indicator on all geographical levels, and lack of assessment methodologies.

Outcomes from the MSFD assessments

In 2018, Member States had to update the Good Environmental Status (GES) assessments performed under Marine Strategy Framework Directive Article 8. The present dashboard displays the overall status reported by countries for the features, where the results show which is the percentage of assessments where GES has been achieved, not achieved or is unknown or not assessed.