Glossary - Living Roofs in Integrated Urban Water Systems - page 172

Stormwater runoff : in urban environments, precipitation that is not soaked
(iniltrated) into the ground, evaporated from surfaces, transpired by plants,
or harvested for reuse becomes stormwater runoff.
Succulents : plants typically native to arid climates that store water within the
plant structure (stems and leaves) to help survive during extended periods of
drought, when soil moisture may be limiting.
Sustainable urban drainage systems (SUDS) : a term synonymous to BMP and
SCM, typically used in the UK.
Total suspended solids (TSS) : a measure of particulate pollutants deined by
the analytical method, without speciic composition. TSS is considered ubiqui-
tous in urban runoff; its control is almost universally required where stormwa-
ter quality regulations are in place. In itself, there can be many receiving
environment and infrastructure impacts.
Two-ply SBS : a common membrane system used for waterprooing decks and
roofs. Made of two layers of a styrene butadiene styrene (SBS), a kind of
elastic asphalt that is modiied with synthetic rubber, the membrane can be
either torched down or mechanically fastened.
Urban agriculture : a movement for a locally produced urban food supply or
urban food supply supplement. Justiications for urban agriculture include:
minimizing food travel distances and therefore carbon footprint, offsetting a
food selection deicit, providing an educational opportunity, and feeding a
growing niche market for locally grown produce. Urban agriculture is appro-
priate for some living roof scenarios, but is typical of intensive rather than
extensive roofs. As with other intensive roof planting, urban agriculture beds
require more irrigation and a stronger roof structure than extensive roofs, and
may compete with stormwater mitigation objectives.
Water-holding capacity : the amount of water that a growing medium can
store. It is typically measured as moisture content per unit depth of media, or
expressed as a total depth of water per unit area of living roof.
Water sensitive urban design (WSUD) : a term similar to LID and GI, used par-
ticularly in Australia. WSUD is a design and planning approach that focuses on
providing long-lasting and mitigating solutions to stormwater management,
wastewater management, and the general health of watersheds. Like LID and
GI, WSUD advocates for methods that work with nature, incorporating natural
and engineered design solutions.
Watershed : an inclusive area of land from which all water eventually drains to a
given location. The boundary of a watershed is deined by high points in
topography such that all water sources lowing by gravity is encompassed by
the watershed.
Winterization : draining of water in building water systems to prevent water
from bursting pipes and other containers or vessels because of expansion that
occurs during freezing.
Xeriscaping : a plant selection strategy that typically employs native, drought-
tolerant species and is particularly appropriate for arid climates.