Premium
Flow transmission along an arid zone anastomosing river, cooper creek, australia
Author(s) -
Knighton A. David,
Nanson Gerald C.
Publication year - 1994
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.3360080205
Subject(s) - tributary , floodplain , hydrology (agriculture) , flow (mathematics) , environmental science , hydrograph , channel (broadcasting) , geology , flood myth , physics , geography , ecology , mechanics , telecommunications , geotechnical engineering , biology , cartography , archaeology , computer science
Cooper Creek is characterized by an exceptionally wide floodplain and a complex system of anastomosing channels which together can accommodate a large range of highly variable flows. In consequence flood frequency curves are unusually steep. With minimal tributary contribution over the two study lengths — Currareva‐Nappa Merrie (> 400 km) and Nappa Merrie‐Innamincka (32 km) — downstream output is largely controlled by upstream input, so that similar flow regimes and hydrograph forms can be maintained despite transmission losses and the variable activation of channels. Input‐output relationships defined in terms of total flow volume and peak discharge suggest that, above a threshold flow of about 25% duration, transmission losses exceed 75% on average over the Currareva‐Nappa Merrie length. The large difference in absorption between primary channels on the one hand and subsidiary channels and the floodplain surface on the other means that transmission losses vary non‐linearly with stage. They are relatively low when flow is confined to the primary channels, but increase at higher stages as lesser channels and the floodplain are activated. Early levels do not recur until flows of < 0.5% duration are attained when output/input ratios increase rapidly with discharge. The influences of seasonality and background flow on output discharge are small relative to that of input discharge. Despite the long river distance, peak flows at Currareva and Nappa Merrie are well correlated. However, over the shorter Nappa Merrie‐Innamincka length with its more confined system of channels, correlations are better and transmission losses less. They vary from 60% just above the threshold discharge to <10% at flows below 20% duration. Over this length outflow hydrographs can be effectively estimated by the three parameter Muskingum procedure, at least on an event by event basis, but further application must await additional records to understand fully how the parameters vary in an environment where streamflow is transmitted through a highly variable system of channels.