Freshwater Update 86, July 2021

Freshwater Update 86 brings you the latest information from our Freshwater & Estuaries Centre. 

Estimating stream shade at the reach scale

Riparian trees strongly modify stream habitat – most notably by shading. Riparian shading keeps stream water cool and inhibits the growth of nuisance aquatic algae and plants (Figure 1). Most of New Zealand’s approximately 400,000 km of stream length was originally heavily shaded by native riparian forest but clearing trees for agriculture and other uses has exposed many streams to direct solar heating.

The prodigious rainmaker that hit Canterbury earlier this month saw NIWA field teams out in the elements collecting flood data from bridges, cableways and jetboat gaugings.