- Scale is a key issue for NFM. Current catchment research projects in various regions may shed light as NFM techniques increase and diversify.
- Holistic approach is a ‘structural’ issue for NFM. Disciplines normally associated only with water-supply have yet to be factored into flood-risk. (ie ‘Water-the-Asset’ necessarily regulating the conveyance and quality of ‘Water-the-Liability’)
- Landuse is a key issue.
- ‘Human’ landowner uncertainty can overshadow technical ‘physical’ uncertainty.
- Gravity brings land-drainage benefit but demands also best (CAP) practice from upstream landusers.
- WFD restrains traditional riparian rights. Dirty angry water does not convey any ‘Good’.
- 30-40RP events are indeed the problem. 1.5% risk is insurable. 5-10% risk is unlikely to be associated with blight.
- In spite of reservations of some contributors, there is evidence that ‘Hydrodynamic’ NFM does respond to extreme events. Core-data/calibration for the Upper Severn 2D hydraulic model was the 1998 (c. 15RP) event. + 23% green-storage is worth having. By way of example in Upper Severn, if Buttington-Munlyn were to be rolled out, downstream Pool Quay (‘R’) assets would again be insurable.
- ‘Hydrologic’ NFM is arguably more diffuse than ‘Hydrodynamic’ NFM . . . more closely aligned perhaps to water-the-asset, groundwater flow and WFD ‘good’.
- Lateral impact is becoming an ever more significant issue for ‘Point-Source-Attenuation’ (ie hard structures such as dams & levees).
- On the other hand Diffuse Water Attenuation from Agriculture (let’s call it DWAA – albeit initially a poor-relation of the more celebrated DWPA) is capable of delivering ‘goods’ without lateral grief.
- ‘Geomorphological’ NFM does deliver (click here) . . . It has done so for decades/centuries. Engineered NFM will deliver more productively. NFM is only able to deliver low-impact because of its diffuse ‘credentials’. This is where scale enters the equation.
- For catchment-scale NFM to be effective, ‘multiple’ is perhaps the key keyword – multiple locations each delivering multiple benefits (and thereby also political approval !!). Small steps; virtuously ubiquitous.
- The only other show in town would appear to be private ‘Resilience’; favoured indeed by government for its low public cost, but would our Victorian forebears have had much pride in exhorting ‘Resilience’ other than as a back-stop pending delivery of communal resource?
- Not least because Resilience is vulnerable to commercial interest groups.
Indeed interesting territory . . . . particularly, perhaps, for engineers in the networking age . . . . accumulating iterative effect from diffuse locations could be just the ticket for networked (student even) ‘diffuse’ research groups . . . (that said, there will need to be ‘top-down’ input in respect of standardized data and broad adoption of OSS utilities such as Python, Quantum and Anuga to broaden the ‘ownership’ of effective solutions).
Multiple Benefits of High Friction Floodplains 