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Armidale, Australia

Jenkins R.B.,University of New England of Australia | Frazier P.S.,Eco Logical Australia
Wetlands | Year: 2010

Current high-resolution remote sensing provides the means to accurately map upland swamp boundaries and vegetation communities in eastern Australian coastal woodlands. The aim of this study was to develop baseline methods for upland swamp definition and change detection that can be routinely applied in an operational setting. Airborne laser scanning was used to define swamp boundaries, image classification was used to describe vegetation communities, and post-classification comparison used to assess temporal variation in community composition over the period 2006-2007. We found that swamp boundaries could be accurately located along the sharp swamp-fringing tree ecotone (accuracy 98%), which provided a definitive feature to support both short- and long-term monitoring. Wet Heath and Dry Heath areas were well defined by image classification, and generally approximate the field-defined perennial vegetation communities of the Tea Tree Thicket and Sedgeland Heath Complexes. Temporal changes to Wet-Dry Heath extent appear to reflect growth phenology, rather than community composition. The proportion of non-vegetated area was less variable, hence an increase in bare ground is likely to be a robust indicator for impact assessment monitoring. © 2010 Society of Wetland Scientists. Source

Munoz-Robles C.,University of New England of Australia | Reid N.,University of New England of Australia | Frazier P.,Eco Logical Australia | Tighe M.,University of New England of Australia | And 2 more authors.
Catena | Year: 2010

Gullies initiate when the equilibrium within a drainage line is upset by increased discharge or decreased soil resistance to detachment and transport of soil particles, and is triggered and accelerated by human-induced changes to vegetation cover. Woody encroachment is the increase in density, cover, extent and biomass of woody plants, and can result in low ground cover, which increases the potential of soil erosion. This paper reports the relationships between gully erosion and site characteristics such as topography, vegetation cover and road infrastructure in a 120-km2 study area of semi-arid woodland subject to woody encroachment in south-eastern Australia. This study characterised gully morphology and activity, identified the factors related to gully volume, and estimated the topographic thresholds for sub-catchments subject to woody encroachment. Firstly, relationships between gully volume, activity, topography, vegetation cover and road infrastructure were explored. Secondly, site characteristics of 32 sub-catchments with and without gullies were compared. Finally, the topographic thresholds for unstable and stable sub-catchments with and without gullies, respectively, were estimated using the slope - drainage area relationship (S=aA-b). All gullies were active and high gully volume was related to large sub-catchments, long gullies and short distances to roads. Stable sub-catchments (without gullies) had gentler slopes, higher foliage projective cover and ground cover than unstable sub-catchments (with gullies). When data for sub-catchments with and without gullies were combined, the main factors related to gully volume were drainage area at the gully or stream heads and their local slope, and ground cover. The mean topographic threshold for gully development provided insights into the drainage area and slope conditions needed for gully development. Gully erosion in the study area is most likely the result of interactions among topography, vegetation and human-made structures (roads) in space and time. The results of the study advance our understanding of gully erosion dynamics in areas of woody encroachment, and can be used to identify areas susceptible to gullying. © 2010 Elsevier B.V. Source

Cresswell R.,Eco Logical Australia
The Art and Science of Water - 36th Hydrology and Water Resources Symposium, HWRS 2015 | Year: 2015

Governing bodies across Australia and New Zealand are more and more looking at the interaction of surface water and groundwater resources as part of overall natural resource planning approaches. As part of the process of developing catchment management strategies and associated policies, catchment scale water quantity and quality modelling has become an essential tool to test policy options and management scenarios and to predict outcomes of environmental manipulations. Catchment management models targeting systems with both surface and groundwater influences are most useful if an integrated approach is taken where both surface water and groundwater interactions can be explicitly captured, even in a simplified manner, to explore options for managing conjunctive use and/or cumulative impacts of nutrients on receiving waterways. Integrated catchment models were constructed in the eWater Source modelling platform which has strong core functionality in hydrology, pollutant generation and water management modelling. Source has been designed specifically to enable customization via the use of plugins. In order to capture the surface water-groundwater interactions (including nutrient pathways through groundwater), a characteristic of many catchments, Jacobs has used several approaches for its representation. Approaches such as the inbuilt surface water-groundwater interaction methods within eWater Source, a custom simplified regional surface water-groundwater interaction model (Network Groundwater Model) and a coupled Source-Modflow model have all been used as part of project applications. Through the use of these project examples, this paper will discuss the use of these models, conceptual calculations and catchment applications in Australia and New Zealand as well as its application to the broader catchment modelling community for future management applications. © 2015, Engineers Australia. All rights reserved. Source

Munoz-Robles C.,University of New England of Australia | Frazier P.,Eco Logical Australia | Tighe M.,University of New England of Australia | Reid N.,University of New England of Australia | And 2 more authors.
International Journal of Applied Earth Observation and Geoinformation | Year: 2012

The amount and distribution of vegetation and ground cover are important factors that influence resource transfer (e.g. runoff, sediment) in patterned semi-arid landscapes. Identifying and describing these features in detail is an essential part of measuring and understanding ecohydrological processes at hillslope scales that can then be applied at broader scales. The aim of this study was to develop a comprehensive methodology to map ground cover using high resolution Quickbird imagery in woody and non-woody (pasture) vegetation. The specific goals were to: (1) investigate the use of several techniques of image fusion, namely principal components analysis (PCA), Brovey transform, modified intensity-hue-saturation (MIHS) and wavelet transform to increase the spatial detail of multispectral Quickbird data; (2) evaluate the performance of the red and near-infra-red bands (NIR), the difference vegetation index (DVI), and the normalised difference vegetation index (NDVI) in estimating ground cover, and (3) map and assess spatial and temporal changes in ground cover at hillslope scale using the most appropriate method or combination of methods. Estimates of ground cover from the imagery were compared with a subset of observed ground cover estimates to determine map accuracy. The MIHS algorithm produced images that best preserved spectral and spatial integrity, while the red band fused with the panchromatic band produced the most accurate ground cover maps. The patch size of the ground cover beneath canopies was similar to canopy size, and percent ground cover (mainly litter) increased with canopy size. Ground cover was mapped with relative accuracies of 84% in the woody vegetation and 86% in the pasture. From 2008 to 2009, ground cover increased from 55% to 65% in the woody vegetation and from 40% to 45% in the pasture. These ground cover maps can be used to explore the spatial ecohydrological interactions between areas of different ground cover at hillslope scale with application to management at broader scales. © 2011 Elsevier B.V. Source

Thompson J.A.,University of New England of Australia | Lamb D.W.,University of New England of Australia | Frazier P.S.,Eco Logical Australia | Ellem B.,University of New England of Australia
Environmental Earth Sciences | Year: 2011

This paper reports on the design and implementation of a program to monitor the surface effects of longwall mining-induced subsidence on wine grape yields within vineyards of Australia's Hunter Valley. Implemented in 2003, this five-year project incorporated a multi-scale, multi-temporal, sliding window monitoring design synchronised with progression of longwall panels. On the vineyard-block scale, individual vine panels were sampled for grape yield. On the regional scale measures of vine photosynthetically active biomass were obtained from remotely sensed, Quickbird satellite imagery. All data were analysed in conjunction with three identified subsidence "zones": minimum subsidence associated with chain-pillars, maximum subsidence associated with the longwall, and a zone corresponding to the transition between them. Visual observations conducted throughout the campaign confirmed the occurrence of isolated localised surface cracking, particularly in areas of maximum soil tension. However, both vineyard and block-scale data indicated no obvious, systematic mining-induced viticultural effects in the study site investigated during the study period. Rather, observed trends in vine yields were better explained by vine biophysical responses to climatic factors. © 2010 Springer-Verlag. Source

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