Pembrokeshire and Ceredigion Rivers Catchment Flood ...

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The impact of climate change and future flood risk Future flood risk will be influenced by climate change, changes in land use (for example urban development) and rural land management. Sensitivity testing identified that the main driver of change to future flood risk is climate change with an increase in urban development affecting some areas. Changes in land management or land use in rural areas may cause localised effects but are not likely to have catchment wide impacts. 200 150 100 50 0 Aberaeron The following scenario was used to analyse future flood risk: • 20 per cent increase in peak river flows; • a total sea level rise of one metre by the year 2100; • 7 per cent and 3 per cent increase in urban development in the Mwldan and Clarach catchments, respectively. This will increase the cover of impermeable surfaces so that more run-off is generated during rainfall events and water moves more quickly into watercourses. Figure 2. Current and future (2100) numbers of properties at risk from a 1% AEP flood event 250 Aberystwyth Cardigan Clarach, Bow St and Penrhyn-coch 10 Environment Agency Wales Pembrokeshire and Ceredigion Rivers Catchment Flood Management Plan Assuming that the current level of flood risk management continues, we estimate that by 2100 the number of properties at risk from the 1% AEP flood event will increase from approximately 1,100 to around 2,500, unless actions are taken to manage the increasing risks. Figure 2 shows the difference between current and future flood risks from a 1% AEP flood event. The most significant increases in future risk occur in Haverfordwest, Aberystwyth, Llanybydder, Aberaeron and Llanrhystud. Fishguard Haverfordwest Lampeter Llandysul Llanrhystud Llanybydder Newcastle Pembroke Pontrhydfen- Emlyn digaid Solva Tregaron Current Future
Flood risk generally increases significantly across the entire CFMP area, with only a few exceptions. The greatest flood risk is in Haverfordwest and Aberystwyth with notable increases also seen in Cardigan, Llandysul, Aberaeron and Llanybydder. A summary of key locations at risk is provided in Table 3. Table 4 shows the infrastructure at risk in the future. There is an increase in the number of electricity sub-stations (increased from 5 to 7) and there is also a railway station in Aberystwyth at future flood risk. There is an 11 per cent increase in agricultural land at risk in a 1% AEP flood event (increased from 85 km 2 to 94 km 2). While there is a broadly similar increase across the CFMP area, the Teifi catchment, being the largest, sees the greatest effect. A small increase is seen in the number of international and nationally designated environmental sites at risk in a future 1% AEP (increased from 96 to 103), and in the number of historic monuments (increased from 16 to 33). However, the impact on these sites is difficult to quantify and will vary widely depending on their features of interest. We expect surface water, and possibly groundwater, flooding will increase. Organisations will need to work together to investigate and manage this flood risk in the future. Table 3. Key locations at risk in a future (2100) 1% AEP flood event Number of properties at risk Locations > 1,000 None 500 to 1,000 None 100 to 500 Haverfordwest, Aberystwyth, Llanrhystud, Lampeter 50 to 100 Clarach, Bow St and Penrhyn-coch, Llanybydder, Aberaeron, Llandysul 25 to 50 Pembroke, Solva, Tregaron, Fishguard, Newcastle Emlyn, Pontrhydfendigaid, Cardigan Table 4. Infrastructure at risk in a future (2100) 1% AEP flood event 1 emergency response centre 7 electricity sub-stations 3 sewage and water treatment plants 1 railway station 1 telephone exchange > 5 kilometres of roads > 2 kilometres of railway line Cardigan on the River Teifi Environment Agency Wales Pembrokeshire and Ceredigion Rivers Catchment Flood Management Plan 11
Page 1 and 2: Pembrokeshire and Ceredigion Rivers
Page 3 and 4: Introduction The Pembrokeshire and
Page 5 and 6: The purpose of a CFMP in managing f
Page 7 and 8: Map 1. Location and extent of the P
Page 9 and 10: Depending on the nature of the envi
Page 11: Some of the ways in which we curren
Page 15 and 16: Table 5. Policy options ➜ Policy
Page 17 and 18: Sub-area 2 Upper Teifi Our key part
Page 19 and 20: Sub-area 4 Western Coastal Rivers O
Page 21 and 22: Sub-area 6 Western Commercial Area
Page 23 and 24: ■■ Sub-area 1 - Northern Coasta

Pembrokeshire and Ceredigion Rivers Catchment Flood ...

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