Brackenford is a market town in northern England. Option 1 would build embankments and flood walls along the River Brack through the town (£9 million). Option 2 would build a flood storage area on 200 hectares of farmland about 2 km upstream, plant about 300 hectares of woodland and build leaky dams on moorland streams (£13 million). Figure 1 shows the River Brack catchment and Option 2.
To what extent would Option 2 be more sustainable than Option 1?
Model answer
A sustainable option meets the needs of people today without reducing the ability of future generations to meet theirs, balancing social, economic and environmental needs.
Environmentally, Option 2 is clearly more sustainable. It works with natural processes across the whole catchment. Figure 1 shows planned woodland on the moorland and farmland in the upper catchment; the trees would intercept rain and increase infiltration, reducing runoff, and they would also create habitats, store carbon and reduce soil erosion. The flood storage area could become a wetland habitat. Option 1 relies on concrete and earth walls and brings no environmental benefits.
Option 2 also tackles the cause of flooding - water running off the steep moorland quickly - rather than just holding the water in the channel. This means it reduces flood risk downstream in Lowthorpe as well as in Brackenford, whereas Option 1 would pass more water down to Lowthorpe and increase its risk. As climate change brings wetter winters, storage and slower runoff will keep reducing peak discharge, but walls may have to be raised.
Economically, Option 1 is cheaper: about £11.5 million over 50 years against about £17 million for Option 2. However, Option 2 brings wider benefits that are not counted in these costs, such as carbon storage, wildlife and lower flood risk downstream, and it would not need expensive raising in future.
Socially, Option 2 has weaknesses. It would take about 20 years for the trees to grow and the scheme to work fully, so people in Brackenford would remain at some risk, whereas Option 1 would protect 470 properties within 2 years. Farmers such as the one at Hollins Farm would lose the use of land when the storage area floods and when fields are planted with trees, so fair compensation is needed. Figure 1 also shows that the storage area is only on the River Brack, so floodwater from Hollin Beck, which joins in the town, would not be held back. Similar schemes, such as 'Slowing the Flow' at Pickering, have shown that natural flood management can work, but it takes time.
Overall, Option 2 is more sustainable than Option 1 to a large extent, because it benefits the environment, protects places downstream and copes better with future climate change. It is less sustainable socially in the short term, so combining it with temporary measures such as flood warnings would make it even more sustainable.
Explanation
Level 3 answers define sustainability, compare both options across the social, economic and environmental strands, use the map (where the storage area and woodland are, and what they do not cover) and costs, and reach a judgement on 'to what extent'. Good answers notice that the most sustainable option can still have short-term social costs.
