Beds of Lakes and Rivers Intro. to the beds of lakes and rivers - - PowerPoint PPT Presentation
Beds of Lakes and Rivers Intro. to the beds of lakes and rivers Drain maintenance provisions Stream piping provisions Dr Michael Greer Senior Scientist Freshwater Intro. to the Beds of Lakes and Rivers The importance of the bed The
Dr Michael Greer Senior Scientist – Freshwater
include:
– Substrate, size, composition and diversity; – The number and size of habitats types; and – The availability of woody debris
functions of the bed
1962 2017
Without drainage With drainage
– Trapped in spoil – Dry out – Eaten by birds
e) Sediment condition of Section 5.5.4 of the proposed Plan excluded as it generally will not be met f) To reduce detrimental changes to the shape of the bed and banks g) To reduce the rate at which fish and invertebrates are stranded during clearing (current wording to prescriptive) h) To reduce mortality rates of fish and kōura removed from drains during clearing
i) To reduce the risk of the sediment removed from drains during clearing re-entering the waterway j) To ensure that refuge areas are provided in cleared reaches, so that fish and invertebrates do not have leave in order to find cover k) To ensure that short sections of plants are left at the downstream end of cleared reaches to trap sediment (does not currently achieve this)
f) Allow for deepening and widening of the channel to allow construction of artificial fish refuge structures (links to j) g) Should be deleted as it may be detrimental in some instances h) Should be amended to ensure that kākahi (freshwater mussels) are also recovered from spoil during drain clearing operations
– Retention of entirely un-cleared sections at regular intervals along the targeted reach; and – the construction of fish refuge bays
– Hydrology; – Morphology; and – Riparian cover