Change in tidal prism

The tidal prism is the volume of water exchanged through a coastal or transitional system typically measured between Mean Low Water Spring (MLWS) and Mean High Water Spring (MHWS). The available tidal prosim displays a relationship with the geometry of the water body, the tidal regime and available accommodation space.

The tidal prism of an estuary or tidal inlet is dependent on the geometry of the basin in terms of surface area and mean water depth, the tidal range, and, to a lesser extent, freshwater inflow. The tidal prism is an indicator of the volume of water within a water body while the residence time of water and sediment exchange potetnial are dependent upon the inlet dimensions and water exchange capacity at varying stages of the tidal cycle. Changes in accommodation space, tidal regime and the geometry of the water body can lead to fundamental alterations to the habitats that the water body can support. As most coastal and transitional systems (geomorphological features and habitats) are in a state of dynamic equilibrium with the tidal prism, any changes to the prism shall manifest as changes to these features at the scale of the entire system, though the impact of these changes on any one feature may vary at a variety of spatial and temporal scales across the system.

Impacts and causes

The following engineering activities are likely to cause changes to the tidal prism of an estuary or inlet: