156
G. Jones
even a permanent basis provided their loss would generate an additional
protection to other more valuable areas. In this category might also fall those
areas which cannot be economically protected from flooding. This category
was weighted at -0.5. Forfeited areas should not be viewed as valueless areas
but contribute a valuable protective role and, in addition, contributing
important new sites for coastal wet lands to replace those lost by inundation
elsewhere in the estuary
Weightings have been allocated on the assumption that the provision of flood
protection would be most cost effective if it alleviated the first phase of potential
flooding (a flood in excess of 5.0 metres above mean high water spring tides for which
flood protection exists). Data has been calculated for flood scenarios at 0.3, 0.6 and 1.0
metre above the critical figure of 5.0 metres above mean high water spring tides high
tide. Weightings for 0.6 and 1.0 m scenarios have been allocated proportionately lower
weighting values than that for the 0.3 m scenario on the assumption that money spent
on raising the flood defence system to restrict the impact of the 0.3 m flood would buy
additional time beyond 2030 in which further changes in land use could be assessed in
the light of prevailing conditions. It is possible that during this additional time period
the inter-governmental actions taken since the Montreal Protocol in 1987 and
subsequent meetings would limit the release of greenhouse gases and lead to a
reduction in the rate of sea level rise.
The severity of flooding in each grid square was calculated as
a function of the length of flooded coastline in each grid square multiplied by
the weighting factor provided in Table 1
the area in hectares of flooded land in each grid square multiplied by the
appropriate weighting factor
Analysis of Flood Scenario
The results obtained from the flood assessment are presented as Flood Loss Scores
(F.L.S.)(see Fig. 4).
Map section 1 Grid squares 1a, 1b, 1c
A flood of 0.3 metres would extend over a narrow flood zone coincident with the raised
beach running east-west throughout the area. Although the total amount of flooded
land would be small, 152 ha, the potential for disruption is high. It is unlikely that
domestic property would be flooded but ground water flooding could result in rising
dampness in properties with inadequate damp courses. The egress of water from storm
water drains would be prevented thus adding to the accumulation of surface water on
roads. A rise in flood water to 0.6 metres would flood an additional 93 ha of the area,
confined mainly to railway land. Disruption to road and rail traffic could occur. An
additional narrow strip of land would be inundated by the 1.0 meter flood and could
G. Jones
even a permanent basis provided their loss would generate an additional
protection to other more valuable areas. In this category might also fall those
areas which cannot be economically protected from flooding. This category
was weighted at -0.5. Forfeited areas should not be viewed as valueless areas
but contribute a valuable protective role and, in addition, contributing
important new sites for coastal wet lands to replace those lost by inundation
elsewhere in the estuary
Weightings have been allocated on the assumption that the provision of flood
protection would be most cost effective if it alleviated the first phase of potential
flooding (a flood in excess of 5.0 metres above mean high water spring tides for which
flood protection exists). Data has been calculated for flood scenarios at 0.3, 0.6 and 1.0
metre above the critical figure of 5.0 metres above mean high water spring tides high
tide. Weightings for 0.6 and 1.0 m scenarios have been allocated proportionately lower
weighting values than that for the 0.3 m scenario on the assumption that money spent
on raising the flood defence system to restrict the impact of the 0.3 m flood would buy
additional time beyond 2030 in which further changes in land use could be assessed in
the light of prevailing conditions. It is possible that during this additional time period
the inter-governmental actions taken since the Montreal Protocol in 1987 and
subsequent meetings would limit the release of greenhouse gases and lead to a
reduction in the rate of sea level rise.
The severity of flooding in each grid square was calculated as
a function of the length of flooded coastline in each grid square multiplied by
the weighting factor provided in Table 1
the area in hectares of flooded land in each grid square multiplied by the
appropriate weighting factor
Analysis of Flood Scenario
The results obtained from the flood assessment are presented as Flood Loss Scores
(F.L.S.)(see Fig. 4).
Map section 1 Grid squares 1a, 1b, 1c
A flood of 0.3 metres would extend over a narrow flood zone coincident with the raised
beach running east-west throughout the area. Although the total amount of flooded
land would be small, 152 ha, the potential for disruption is high. It is unlikely that
domestic property would be flooded but ground water flooding could result in rising
dampness in properties with inadequate damp courses. The egress of water from storm
water drains would be prevented thus adding to the accumulation of surface water on
roads. A rise in flood water to 0.6 metres would flood an additional 93 ha of the area,
confined mainly to railway land. Disruption to road and rail traffic could occur. An
additional narrow strip of land would be inundated by the 1.0 meter flood and could