Modelling hydrological connectivity of tropical floodplain wetlands via a combined natural and artificial stream network

Karim, Fazlul, Kingsey-Henderson, Anne, Wallace, Jim, Godfrey, Paul, Arthington, Angela H., and Pearson, Richard G. (2014) Modelling hydrological connectivity of tropical floodplain wetlands via a combined natural and artificial stream network. Hydrological Processes, 28 (23). pp. 5696-5710.

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Abstract

The ecological condition and biodiversity values of floodplain wetlands are highly dependent on the hydrological connectivity of wetlands to adjacent rivers. This paper describes a method for quantifying connectivity between floodplain wetlands and the main rivers in a wet tropical catchment of northern Australia. We used a one-dimensional hydrodynamic model to simulate time-varying water depths across the stream network (i.e. rivers, streams and man-made drains). The timing and duration of connectivity of seven wetlands (four natural and three artificial) with the two main rivers in the catchment were then calculated for different hydrological conditions. Location and areal extent of the wetlands and the stream network were identified using high-resolution laser altimetry, and these data formed key inputs to the hydrodynamic model. The model was calibrated using measured water depths and discharges across the floodplain. An algorithm was developed to identify contiguous water bodies at daily time steps, and this gave the temporal history of connection and disconnection between wetlands and the rivers. Simulation results show that connectivity of individual wetlands to both rivers varies from 26 to 365 days during an average hydrological condition. Location, especially proximity to a main river, and wetland type (natural stream or artificial drain) were identified as key factors influencing these levels of connectivity. Some natural wetlands maintain connection with the river for most or all of the year, whereas the connectivity of some artificial wetlands varies from 26 to 36 days according to their patterns of network connection to adjacent rivers – a result that has important implications for the accessibility of these types of wetland to aquatic biota. Using readily available river gauge data, we also show how connectivity modelling can be used to identify periods when connectivity has fallen below critical thresholds for fish movement. These connectivity patterns within the floodplain network are central to the setting of river flows that will meet environmental requirements for biota that use floodplain wetlands during their life history.

Item ID: 32234
Item Type: Article (Refereed Research - C1)
Keywords: connectivity; environmental flow; hydrodynamic modelling; LiDAR; MIKE 11; wetland
ISSN: 1099-1085
Funders: Commonwealth Scientific and Industrial Research Organisation (CSIRO), Reef and Rainforest Research Centre
Date Deposited: 26 Mar 2014 02:20
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960807 Fresh, Ground and Surface Water Flora, Fauna and Biodiversity @ 100%
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