17.5.1 River and Floodplain Management NNBF River and floodplain management NNBF (as illustrated in Figure 17.15) include river and floodplain restoration with wetland and off-line storage options. These features provide a wide range of environmental and cultural co-benefits and may be applied to any part of a watershed with varying degrees of impacts or reductions in FRM. The river restoration features attempt to restore natural physical processes and features to the channel and adjacent floodplain. Floodplain and wetland enhancement features restore natural connections to floodplains, provide floodwater storage, and give aquatic species access to areas that were once naturally available. Off-line storage NNBF adapt and restore natural processes to retain and attenuate floodwaters in a managed way. Strategically placed and designed containment structures increase water storage, effectively reducing discharge downstream and providing FRM benefits to the watershed. Note that in applying river and floodplain management NNBF, it is important to recognize their position in the catchment. Measures in the headwaters (upper catchment) intend to slow the flow by means of retention, tree planting, or leaky barriers. In the middle reach, where the discharge is generally higher, NNBF intend to increase (restore) discharge capacity to reduce peak water flood levels. Side channels are an example of such a measure. Although one can also increase the discharge capacity of a river by dredging the main channel (and hence, making the main channel deeper or wider), dredging as such is not normally considered to be an NNBF. Figure 17.15. Schematic of River and Floodplain Management
Woody Material
River and Floodplain Management • Slows flood flows • Encourages flood storage • Creates bypasses to move water away from communities • Provides ecological/aquatic habitat benefits
The following includes some of the many guides that give information on river and floodplain management NNBF: • The NFM Manual (Wren et al., forthcoming) • Building Community Resilience with Nature-Based Solutions: A Guide for Local Communities (Federal Emergency Management Agency 2020) • Building with Nature: Creating, Implementing and Upscaling Nature-Based Solutions (van Eekelen and Bouw 2020)
17 | Benefits and Challenges in the Application of NNBF in Fluvial Systems
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