Draft Details

This Standard provides a framework for initiating, planning, implementing, and adaptively managing NbS for watershed-based flood (pluvial & fluvial) and erosion management. It emphasizes evidence-based decision making, risk assessment, and interest holder engagement to ensure that NbS remain effective under changing environmental conditions. The standard includes guidance to facilitate the adoption of NbS at various scales and considerations to inform their selection, design, and implementation.

1.1 Inclusions

This Standard applies to watershed-based flood and erosion management and projects including:

a)  fluvial flooding caused by overflowing of rivers and streams;

b)  pluvial flooding caused by overwhelmed drainage systems;

c)  all orders of stream channels, small lakes, and their associated floodplains and estuaries;

d)  vegetation ecosystems associated within fluvial watersheds (e.g., wetlands, ponds, riparian zones, forests, small lakes, etc.);

e)  erosion processes from:

i)         fluvial flooding

ii)        pluvial flooding ice jam flooding;

iii)       intense rainfall not necessarily causing flooding;

iv)       permafrost thaw; and

v)        streambank soil erosion from natural channel migration;

f)   green stormwater infrastructure or low impact development (LID) for watershed-based flood and erosion management;

g)  both rural and urban areas.

1.2 Exclusions

While the approaches contained within this standard could be applied more broadly, the following is explicitly excluded from this standard:

a)  application of NbS to address the following hazards:

i)         coastal or tidal flooding and erosion;

ii)        large Lakes (e.g., Great Lakes);

iii)       regulated lakes/reservoirs (i.e. water impounded by dams for hydropower production);

iv)       groundwater flooding;

v)        landslides; and

vi)       rare but potentially very high magnitude flood events (e.g., greater than the 500-year flood);

b)  grey infrastructure approaches to watershed-based flood and erosion management (so-called grey because of the use of concrete in many engineered structures);

c)  governance and policy alignment for NbS; and

d)  funding mechanisms for NbS.

1.3 Terminology

In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.