CHARTERED SURVEYORS

 

Project 1: Lune Estuary Habitat Management Study
Client: Lancaster City Council    Funding: DEFRA

In accordance with their Shoreline Management plans for the Lune Estuary and the eastern shores of Morecambe Bay, Lancaster City Council wished to undertake numerical modelling of the natural processes affecting evolution of the shoreline habitat. The purpose of the exercise was to assess sustainability and environmental impacts of various options for coastal management.

Hydrosurveys were commissioned to undertake a comprehensive survey and data-gathering exercise, providing raw data on tidal, fluvial and sedimentary processes. An ecological mapping study was also undertaken to assess the status of inter-tidal habitats and communities, including vegetation, invertebrates and bird populations.


A series of ten water data recording stations were set up at strategic locations along the estuary and offshore, for continuous monitoring of tide and wave activity, currents, suspended sediments and salinity

With many parts of the project area characterised by soft mud and shifting sands, this difficult working environment required a range of different techniques to gain access to instruments in remote locations. Several different types of mounting structure were tested to ensure that recording equipment would remain in position for the duration of the study.

In some locations, the instruments were maintained and calibrated in-situ by taking advantage of short periods of tidal exposure. In others, where the instruments were permanently submerged or on muddy substrate, the platforms were raised periodically onto the vessel for maintenence, and then relocated using specially adapted lifting and positioning gear.

 

 


The project has involved a multi-disciplinary team covering topographic and hydrographic survey, ecology and data instrumentation.

The first task was to produce a 3D digital terrain model of the estuary and offshore approaches, including the river channel as far upstream as Lancaster with adjacent tidal marshes, seawalls and shipping channels. This required fully integrated topographical and bathymetric surveys covering an area of approximately 4000 ha and using techniques suitable to gain access to all types of terrain. The model included areas of low lying agricultural lands reclaimed from the sea at various stages over the last century.

The terrain model will be used for predictive studies of channel evolution, erosion and accretion, and to assess water levels and coverage under different shoreline management regimes.