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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Managing deltas : Floodplain management challenges following rapid landscape transformation
Floodplain management challenges following rapid landscape transformation
Author : PHILIP WALLACE (1)
ABSTRACT
The Rangitaiki, Tarawera and Whakatane Rivers drain a combined catchment of 6000 km2 in the eastern Bay of Plenty
of New Zealand. The rivers rise in the Volcanic Plateau and hill country before flowing out over the Rangitaiki Plains and
into the sea. This alluvial floodplain covers an area of about 250 km2. Until the end of the 19th century, the floodplain
was largely undeveloped, much of it being a vast wetland, ¡°a road-less wilderness¡±, with myriad channels and with only
limited outlets through sand dunes to the sea. Large-scale drainage and flood protection works on the Plains
commenced in the early part of the 20th century, allowing the establishment of wide-scale dairy farming. Today a
system of stopbanks (levees), floodwalls, pumps, floodgates and bank protection measures is in place. However a
number of challenges are faced in maintaining design standards, including financial stresses from the cost of repairs
following repeated flood events in recent years, continual subsidence of the floodplain and stopbanks, poor geotechnical
conditions, climate change (sea level rise and increased flood flows) and ecological concerns. A number of potential
measures to deal with these challenges are being considered. Given the parallels between some of the challenges
identified and those being faced by The Netherlands, elements of the latter¡¯s ¡°Room for the River¡± programme may be
appropriate. Indeed, several such measures have been identified and one that has been adopted at this stage is a
programme of investigations and works to increase the capacity of a bypass spillway. A history of the drainage and flood
protection works, and the assessment tools used, is presented, along with discussion of possible futures for the
floodplain
File Size : 938,936 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Managing deltas
Date Published : 20/08/2015
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