This report covers the spring survey of the northern estuary, with provisional figures. Highlighted text marks open questions.[JM1] 

1 Methods

Gauges were read at high and low water, in three steps:

1.     Calibrate each gauge against the datum.

2.     Read it every fifteen minutes.

3.     Reject gaps longer than a month.

Equipment used:

·       Pressure gauges

·       Radar level sensors

·       A survey boat

1.1 Sites

2 Results

Raising the barrier crest by 40 centimetres halves the expected annual damage in the northern estuary.

Figure 1: the surveyed sites.

3 Discussion

The central and southern estuaries gain less, because their defences are already above the 2050 line.