Keywords
wetland, owl, mndwi, modis, tm, cn
Start Date
1-7-2012 12:00 AM
Abstract
Flood inundation and retention are key hydrological characteristics of floodplain wetlands. They are critical to the management of environmental flows in terms of sustaining ecosystem function, biodiversity and habitat suitability. This study developed a methodology for the estimate of potential floodwater retention under floodplain inundation from ecologically significant flood return periods by coupling remote sensing and GIS technologies with spatial hydrological modelling. The Macquarie Mashes located in the central west of New South Wales of Australia were selected as the case study area. The 1-in-10 years annual recurrence interval (ARI) was identified as one of the most important return periods to be investigated. A partial duration flood frequency analysis was applied to time series of observed flow data for generating a return period curve (RPC). Time-series of MODIS 8-day composite imagery (500m resolution) over the period 2000-2011 were related to the 1-in-10 ARI flow rate (ML/day) quantified from the RPC. Inundation in each corresponding image was detected using the modified Normalised Difference Water Index (mNDWI) in ENVI. The potential maximum retention was measured using a spatial hydrological modelling approach, which is driven by the Soil Conservation Service Curve Number (SCS CN) method. Soil and land cover data were collected and intersected to determine spatial distribution of CN in ArcGIS. The resultant retention capacity map was then integrated with inundation extent map to delineate the spatial pattern of potential retention under inundation which has ecological implications in the study area. This study has proved that the integration of remote sensing, GIS and spatial hydrologic modelling can be used to provide essential information as inputs to environmental models for understanding the responses of floodplain and wetland ecosystems and to support the assessment of the benefits of returning water to these environments.
Spatial modelling of potential soil water retention under floodplain inundation using remote sensing and GIS
Flood inundation and retention are key hydrological characteristics of floodplain wetlands. They are critical to the management of environmental flows in terms of sustaining ecosystem function, biodiversity and habitat suitability. This study developed a methodology for the estimate of potential floodwater retention under floodplain inundation from ecologically significant flood return periods by coupling remote sensing and GIS technologies with spatial hydrological modelling. The Macquarie Mashes located in the central west of New South Wales of Australia were selected as the case study area. The 1-in-10 years annual recurrence interval (ARI) was identified as one of the most important return periods to be investigated. A partial duration flood frequency analysis was applied to time series of observed flow data for generating a return period curve (RPC). Time-series of MODIS 8-day composite imagery (500m resolution) over the period 2000-2011 were related to the 1-in-10 ARI flow rate (ML/day) quantified from the RPC. Inundation in each corresponding image was detected using the modified Normalised Difference Water Index (mNDWI) in ENVI. The potential maximum retention was measured using a spatial hydrological modelling approach, which is driven by the Soil Conservation Service Curve Number (SCS CN) method. Soil and land cover data were collected and intersected to determine spatial distribution of CN in ArcGIS. The resultant retention capacity map was then integrated with inundation extent map to delineate the spatial pattern of potential retention under inundation which has ecological implications in the study area. This study has proved that the integration of remote sensing, GIS and spatial hydrologic modelling can be used to provide essential information as inputs to environmental models for understanding the responses of floodplain and wetland ecosystems and to support the assessment of the benefits of returning water to these environments.
