Hapua
Hapua is the Māori term for river-mouth lagoons on mixed sand and gravel (MSG) beaches which form at the river-coast interface where a typically braided, although sometimes meandering, river interacts with a coastal environment that is significantly affected by longshore drift. The lagoons which form on the MSG coastlines are common on the east coast of the South Island of New Zealand and have long been referred to as hapua by the Māori. This classification differentiates hapua from similar lagoons located on the New Zealand coast termed waituna. Hapua are often located on paraglacial coastal areas where there is a low level of coastal development and minimal population density. Hapua form as the river carves out an elongated coast-parallel area, blocked from the sea by a MSG barrier which constantly alters its shape and volume due to longshore drift. Longshore drift continually extends the barrier behind which the hapua forms by transporting sediment along the coast. Hapua are defined as a narrow shore-parallel extensions of the coastal riverbed. They discharge the majority of stored water to the ocean via an ephemeral and highly mobile drainage channel or outlet. The remainder percolates through the MSG barrier due to its high levels of permeability. Hapua systems are driven by a wide range of dynamic processes that are generally classified as fluvial or marine; changes in the balance between these processes as well as the antecedent barrier conditions can cause shifts in the morphology of the hapua, in particular the barrier. New Zealand examples include the Rakaia, Ashburton and Hurunui river-mouths.
Q36451
Māori
Concept
Q187223
lagoon
Concept
Q590219
braided
UNK
Q180537
meander
Concept
Q93352
coastline
Concept
Q120755
South Island
LOC
Q664
New Zealand
LOC
Q6122670
Māori
Concept
Q3895117
paraglacial
UNK
Q1938255
longshore drift
Concept
Q7445303
transporting sediment
Concept
Q1434465
fluvial
LOC
Q1050578
marine
Concept
Q2128994
Rakaia
LOC
Q4804674
Ashburton
LOC
Q14922567
Hurunui
LOC
Q86752518
Hapua
UNK
Q86752518
Hapua
UNK
Q86752518
Hapua
UNK
Q86752518
Hapua
UNK
Q86752518
Hapua
UNK
country
ethnic group
country