Effects of Climate Change

The impacts of Climate Change are well documented and include sea level rise and the potential increase in intensity, severity and frequency of coastal storms. Using the current DEFRA guidance on net sea level rise and climate change, the effects of increased still water levels, and the associated increase in wave height and storm frequency, have been examined for Hastings beach.

This encompasses the added risk of wave overtopping/damage, flooding, influence on sediment transport and changes to the coastline plan shape and beach face gradient over the next 20, 50 and 100 years.

Sea Level Rise

In the Southeast of England anticipated increases in water levels are a combination of two factors. Primarily rising sea levels due to melting ice caps and thermal expansion of the oceans, this is supplemented by the isostatic rebound of Great Britain from the last ice age causing a vertical drop in land levels in the southeast.

DEFRA guidance on climate change impacts was updated in 2006 replacing the previous projections of a linear rise in sea levels, of 6mm/year in the region, to an exponential curve rising from 4mm/year in 1990 to 15m/year after 2085. Table 1 uses these guidelines to update the key tidal statistics for the next 20, 50 and 100 years. 

Table 1: Predicted tidal levels given current sea level rise projections

Hastings Admiralty Tidal Information with Projected Sea Level Rise (mODN)

Year

MHWS

MHW

MHWN

MSL

MLWN

MLW

MLWS

2010

3.80

2.90

2.00

0.05

-1.60

-2.25

-2.90

2030

3.90

3.00

2.10

0.15

-1.50

-2.15

-2.70

2060

4.18

3.28

2.38

0.43

-1.23

-1.88

-2.43

2110

4.85

3.95

3.05

1.10

-0.55

-1.20

-1.75

To put these changes into context the levels and anticipated return periods for extreme water levels have been updated and graphically illustrated against a recent profile survey at the western end of the harbour beach (Figure 1).

Figure 1: Predicted Sea Level Rise Extreme Water Levels for 2110

 

Storm Frequency/Intensity

In addition to the increases in sea level the frequency and intensity of storm events is also predicted to increase. A 5% increase in wind speeds from 1990-2025 is expected to rise to 10% after 2055, this would be reflected in a comparable rise in wave heights. The problem at the harbour beach will be worse as a consequence of the increased water levels allowing larger waves to reach the beach.

The combination of increased water levels and larger waves will also result in the fleet being subject to an ever increasing probability of disruption/damage from wave overtopping. At some point in the next hundred years this would make the fishing operation untenable without defence works to raise the level of the back beach. It should be pointed out that this is a problem that will affect many areas of the coastline and not just Hastings beach.

Another consequence of the increase in storm frequency is that using the current fishing methodology the fishing fleet will have more days when they are unable to launch the vessels. An effect they have already been subjected too in recent years due to the unnaturally high incidence of storms experienced as part of natural variability.