Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing Platforms and Imaging Techniques

Prepared by

Andrew Marshall Andrew Storey Andrew Marshall Pty Ltd Wetland Research & Management

August 2005 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

CONTENTS

EXECUTUVE SUMMARY ...... iv

INTRODUCTION...... 1 BACKGROUND...... 1 THE FUNCTIONAL HABITAT CONCEPT ...... 2 PROJECT OBJECTIVES...... 2 PHASE I – EVALUATION OF REMOTE SENSING AND IMAGING TECHNIQUES ...... 6 APPROACH ...... 6 SENSOR TECHNICAL SUMMARY ...... 6 SENSOR TECHNICAL EVALUATION...... 8 ° Low-Resolution Satellite Sensors...... 8 ° High-Resolution Satellite Sensors...... 10 ° Airborne Sensors...... 11 ACQUISITION / PROCESSING EVALUATION ...... 13 ACQUISITION / PROCESSING COST...... 13 PHASE I RECOMMENDATIONS ...... 16 PHASE II - FUNCTIONAL HABITAT MAPPING TRIAL ...... 17 APPROACH ...... 17 QUICKBIRD SATELLITE IMAGE ACQUISITION ...... 18 DIGITAL VIDEO IMAGE ACQUISITION...... 19 IMAGE CLASSIFICATION...... 24 COMPARISON OF IMAGING TECHNIQUES -...... 34

SUMMARY OF FINDINGS FROM PHASE I & II ...... 34 QUICKBIRD ...... 34 DIGITAL VIDEO ...... 38 AERIAL COVERAGE OF HABITATS...... 39 CONCLUSIONS ...... 42

RECOMMENDATIONS...... 43 MONITORING SCENARIO #1...... 43 MONITORING SCENARIO #2...... 43 MONITORING PROTOCOL ...... 43 ACKNOWLEDGMENTS ...... 45

REFERENCES...... 45

ii Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

List of Figures, Tables and Plates

FIGURES Figure 1. Example of resolution achieved with Landsat 7 satellite images - 30m image resolution...... 8 Figure 2. Example of resolution achieved with SPOT 4 satellite images– 20m image resolution...... 9 Figure 3. Example of Synthetic Aperture Radar (SAR) image – 10m image resolution ...... 9 Figure 4. Example of simulated multispectral imagery from Quickbird satellite system...... 10 Figure 5. Example of simulated multispectral imagery from Ikonos satellite system...... 11 Figure 6. Comparison between film-based aerial imagery and Ikonos satellite imagery...... 12 Figure 7. Example of scanned film based aerial imagery – 1.0m image resolution...... 12 Figure 8. Selected Reach for the Functional Habitat Mapping Trial...... 17 Figure 9. Ord River discharge at time of aerial survey and ground-truthing ...... 17 Figure 10. Extent and orientation of Quickbird imagery acquired for the lower Ord River ...... 18 Figure 11. Panasonic NV-MX500 digital video camera ...... 19 Figure 12. Digital video flight path – 1st November 2003 ...... 22 Figure 13. Sample digital video image of lower Ord River with resolution of 0.5 metres...... 22 Figure 14. Mosaic of digital video images of reach between Carlton Crossing & Macca’s Barra Camp..23 Figure 15. Results of the mosaicing process in terms of both radiometric and spatial accuracy ...... 24 Figure 16. Results of habitat classification process using ENVI cf the source (Quickbird) image...... 29 Figure 17. Habitat classification legend used for Quickbird satellite and Digital Video imagery ...... 30 Figure 18. Quickbird image classification – full scene results and detail at Carlton Crossing...... 31 Figure 19. Habitat classification of Quickbird images as simple vector entities for the whole study area and detail of the Ord River near Macca’s Barra Camp...... 32 Figure 20. Comparison of habitat classification of Quickbird image and Digital Video image ...... 33 Figure 21. Snag habitat captured as Quickbird image and Digital Video image ...... 35 Figure 22. Quickbird satellite imagery illustrating impact of high off-nadir view angle...... 35 Figure 23. Water penetration characteristics of the Quickbird satellite cf the Digital Video...... 36 Figure 24. Quickbird source image cf same image with enhancement filters ...... 37 Figure 25. Classification results from un-enhanced and enhanced Quickbird satellite images...... 37

TABLES Table 1. Functional habitats of high importance to invertebrate and fish faunas in the lower Ord River....3 Table 2. References providing technical details on each sensor system ...... 7 Table 3. Relevant technical specifications for each system ...... 7 Table 4. Satellite and aerial photography systems further assessed...... 14 Table 5. Estimated image acquisition costs for sensors ...... 15 Table 6. General Digital Video Camera Specifications for Habitat Mapping...... 20 Table 7. Physical units identifiable from imagery ...... 25 Table 8. Functional habitats of high importance to invertebrates with equivalent remote sensing units. ..25 Table 9. Functional habitats of high importance to fish with equivalent remote sensing units...... 25 Table 10. Aerial coverage of physical units as calculated from Quickbird satellite and Digital Video imagery...... 40 Table 11. Comparison of estimated acquisition and image analysis costs...... 44

PLATES Plates 1 – 12. Examples of key habitats for aquatic invertebrates and fish in the lower Ord River, as identified by Storey (2002, 2003)...... 3 Plates 13 – 29. Field verification of physical units identified from remote sensing...... 26

Frontispiece: Quickbird image classification of functional habitats in the lower Ord River in the vicinity of Carlton Crossing and House Roof Hill.

iii Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

EXECUTUVE SUMMARY The current study forms part of an adaptive management programme to monitor and evaluate effects of environmental flow provisions in the Ord River. The aim of the programme is to ensure environmental values downstream of the Kununurra Diversion Dam are protected. Previous investigations identified a range of habitats that were of particular importance to the aquatic fauna in the lower Ord River (LOR), with species of fish and macroinvertebrates associated with specific habitats. The investigations also identified potential risks to selected habitats under revised flow scenarios. Therefore, it was necessary to develop a technique to monitor the areal extent of each critical habitat under revised flow regimes. To this end, remote sensing was identified as a potential means to monitor these habitats.

The current study involved a cost-benefit analysis of remote sensing techniques with subsequent field trial and ground-truthing during the late dry season of November 2003 to identify the most beneficial approach. The cost-benefit analysis identified Quickbird satellite imagery and aerial photography (digital stills and video) as the most accurate and cost effective remote sensing systems to map the extent and distribution of important habitats for fish and invertebrates (functional habitats) in the lower Ord River. Potentially, these systems will both enable mapping of small scale (in the order of metres) habitat/geomorphic units to better assess the risk of losing riverine species under modified flow regimes. Field trialling with ground truthing was then undertaken to assess which of the selected approaches was most effective in mapping the selected habitat units.

Recommended Remote Sensing Platform A recommended monitoring scenario and associated costs will depend to some extent on the area to be monitored, as there are economies of scale with each platform. Acquisition of a single satellite image at the minimum acquisition area (5 km x 12 km) will have cost efficiencies over acquiring digital aerial video over a 12 km reach of river. However, acquisition of a series of satellite images that will cover the whole of the lower Ord River will have substantial costs over flying a series of separate 5 km reaches dispersed along the length of the lower Ord. If the optimum acquisition changes for the Quickbird imagery are possible (i.e. 5 - 10 degrees off-nadir & full pan- sharpened image), then the final recommendation would be to utilize each method optimally in a hybrid mode. If the optimum acquisition changes for the Quickbird imagery are not possible, then Digital video would be the preferred technique, using data acquisition at higher altitude (4,000 feet; 1,219.2m) and an in-cockpit monitor to allow better tracking of the river channel.

Recommended Monitoring Protocol • Baseline habitat mapping should be repeated on at least three occasions (each occasion being a separate dry season) to ensure inter-annual variation is adequately documented prior to a revised flow regime being introduced. • Mapping on each occasion should be standardised to river stage height. • Mapping should be repeated if flood events significantly alter channel and bank habitats prior to implementation of the new flow regime. • Following application of a revised flow regime, mapping should be repeated to assess effects on aerial extent of critical habitats.

iv Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

INTRODUCTION Background Increased pressures on the Ord River water resource as a result of proposed developments have necessitated the preparation of a Water Allocation Plan by the Department of Environment (previously Water and Rivers Commission). Under the Environmental Water Provisions Policy for Western Australia (WRC, 2000), the Commission’s allocation planning process must provide for the protection of water dependent ecosystems while allowing for sustainable use and development to meet the needs of current and future users.

When the Department of Environment (DoE) first undertook the development of a water allocation plan for the Ord (WRC, 1999), the approach taken in determining the environmental provision was a rule of thumb 20th percentile of the natural flows. Little ecological data was available to justify a more sophisticated approach. Public comments on the 1999 Draft Water Allocation Plan considered that the environmental values that had arisen in the 30 years since regulation altered the hydrology, had not been adequately protected. Strategic advice from the Environmental Protection Authority (EPA) recommended that DoE review the proposed environmental water provisions and that maintenance of the riverine environmental values established since the construction of the Ord River Dam (ORD) should be the basis of that review. After seeking advice from a panel with expert knowledge of tropical river ecosystems and undertaking further community consultation, DoE undertook to determine ecological water requirements by comparing changes in the dry season wetted perimeter relative to different discharge levels. DoE concluded that the decrease in depth and wetted perimeter associated with the maintenance of a minimum flow rate of 45 m3.sec-1 from the Kununurra Diversion Dam (KDD) to 57.5 km downstream and 40 m3.sec-1 below that point was an acceptable estimate of the ecological water requirement; i.e. the ‘45/40’ environmental allocation. This was viewed as limiting the change to the dry season flows and hence to the risk of triggering the adverse dry season ecological impacts described by the Scientific Panel. This estimate of the ecological water requirement is expected to provide the basis for a revised Interim Water Allocation Plan for the lower Ord River (in preparation), but which may be reduced in times of drought.

The Environmental Water Provisions Policy for Western Australia (WRC, 2000) requires that the Commission apply effective monitoring and evaluation to ensure that water provisions are met and that environmental values are protected. This is paramount in the Ord River given the interim nature of the environmental flow provision and the lack of scientific certainty on which it is based.

DoE is concerned that reduced flows in the Ord River downstream of the KDD (i.e. the lower Ord River) could result in a decrease in the quantity and quality of habitats identified as important for fish and invertebrates (functional habitat, sensu Storey 2002 & 2003), and this could possibly lead to reduced species diversity and abundance. Therefore, as part of an adaptive management programme, the flow provision will be monitored and evaluated.

1 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

To assess the impact of the 45/40 allocation on the river, DoE intends to survey and map the extent of key habitats in the lower Ord River under current dry season flows using remote sensing techniques. This will allow the distribution and extent of important habitats under the 45/40 flow regime to be compared to current dry season flows (~60 m3.sec-1), and also any future changes in extent detected if lower flows are prescribed under a drought scenario.

The Functional Habitat Concept The functional habitat approach considers the river channel as being composed of distinct habitat units that can be recognised and classified on the basis of their physical and biological attributes. The Functional Habitat Concept proposes that it is easier to monitor visible changes in habitat distribution and extent than it is to detect change in the distribution, abundance and biomass of fish and invertebrates based on infrequent sampling of populations, especially in systems with diverse communities, for which there is little information on the life history requirements of individual species. Storey (2002 & 2003) therefore recommended the ‘Functional Habitat’ approach as a method for management and future monitoring of faunal communities in the lower Ord River, on the precept that it is easier to manage critical habitats, rather than the resident species for which there is little biological information.

Important functional habitats for aquatic macroinvertebrates and fish of the lower Ord River have been identified by Storey (2002 & 2003) (Table 1). They indicate the most important habitats in terms of species preferences/usage and likely susceptibility to changes in flow discharge. Examples of key habitats are illustrated in Plates 1 – 12.

Mapping of the extent and distribution of functional habitats in the Ord River downstream of the KDD is yet to be undertaken. Prior to undertaking mapping, it is necessary to identify the best remote sensing platform and imaging technique for identifying and mapping aerial extent of functional habitat units. Functional habitat may be a sub-unit of large reach-scale geomorphic unit. For example, whilst pools may form relatively discrete habitat units, all pools will not be equivalent in terms of the range of micro-habitats, and therefore biota, found within them. Therefore, an inventory of larger scale habitat/geomorphic units is unlikely to allow an assessment of the risk of losing species from the Ord River system. Functional habitat therefore will need to be measured at the scale of metres rather than 100s of metres or even 10 of metres. To apply the functional habitat approach to monitor changes in the extent and distribution of key habitats for fish and invertebrate fauna it is first necessary to develop an appropriate technique for monitoring changes in functional habitats. The current project investigated the applicability of various methods of remote sensing to map functional habitat in the lower Ord River.

Project Objectives The overall aim of the current project was to identify the most efficient method to remotely survey the aerial extent and distribution of functional habitat in the lower Ord downstream of the KDD.

2 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

This was achieved in two phases. Phase I of the project involved a cost-benefit analysis of various remote sensing techniques that could be applied to mapping habitats of the lower Ord River. Phase II involved a trial remote sensing survey and ground-truthing of the techniques selected on the recommendations of Phase I.

The current report details the findings of both the Phase I Evaluation of Remote Sensing Platforms and Imaging Techniques and the Phase II Functional Habitat Mapping Trial undertaken in the lower Ord in November 2003.

Table 1. Functional habitats of high importance to invertebrate and fish faunas in the lower Ord River downstream of the Kununurra Diversion Dam. Within each fauna component, habitats are in descending order of importance to species/diversity. A more detailed description and specification of each habitat type can be found in Storey (2002 & 2003). Invertebrates Fish Habitat Type Ranked importance Dry Season Wet Season based on fauna diversity, extent & susceptibility to Change Rapids 1.75 Shallow backwaters Shallow backwaters Gravel runs 2.00 Submerged macrophytes Deep backwaters Submerged veg. 2.25 Submerged woody debris Flooded riparian margin Emergent veg. 2.75 Pools Floodplain lagoons Flooded riparian 4.50 Emergent macrophyte Pools Mud/silt 5.00 Gravel runs Submerged macrophytes Sand 5.50 Turbulent rapids Emergent macrophyte Submerged woody debris

Plate 1. Emergent macrophyte habitat: beds of Plate 2. Beds of Persicaria attenuata above the water Phragmites australis are now well established along level at the end of the dry season, but will be lengths of the lower Ord River. inundated in the wet.

3 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Plate 3. Flooded riparian vegetation habitat: dead Plate 4. Flooded shallow backwater habitat, and stressed flooded riparian vegetation at the end important as a refuge for small fish and juveniles of of the dry season, where banks have slumped and larger species to avoid predatory fish. dead vegetation is now inundated.

Plate 5. Rapid habitat: Turbulent rapids Plate 6. Gravel Run habitat: measuring in situ water downstream of Buttons Crossing. quality parameters on a gravel run upstream of House Roof Hill.

Plate 7. Mud/Silt habitat: Mud banks along the Plate 8. Sand habitat: sand edge downstream of waters edge downstream of House Roof Hill. House Roof Hill.

4 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Plate 9. Lower Ord River in 1995, prior to the floods Plate 10. Close-up of a bed of submerged in 2000 & 2001, indicating submerged macrophyte macrophyte Vallisneria americana becoming re- habitat (beds of Vallisneria americana), emergent established in the lower Ord River after Mach 2000 vegetation (Typha domingensis) on banks and in and 2001 floods. channel, and dense riparian vegetation.

Plate 11. Flooded riparian vegetation in April Plate 12. Flooded riparian vegetation, 2002, with a gill net set diagonally across the mid- predominantly Melaleuca spp. near House Roof Hill foreground. in June 2001, typical of this habitat following the wet season.

5 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

PHASE I – EVALUATION OF REMOTE SENSING AND IMAGING TECHNIQUES Approach Although there is a wide range of remote sensing options available, many do not offer the capability of identifying habitat at the scale of assessment required (metres to 10s of metres). The evaluation phase assessed the different options to make recommendations for the Phase II trial survey as well as for future monitoring programmes. The following aspects of each system were assessed: • Technical performance / benefit; • Acquisition cost; • Processing cost; • Ease of acquisition / processing.

The remote sensing platforms evaluated included: • Satellite Sensors (visible spectrum, multi-spectral) - Landsat 7 - SPOT 4 / SPOT 5 - Ikonos - Quickbird - IRS - Aster • Synthetic Aperture Radar (SAR) - Radarsat 1/ Radarsat 2 - Envisat • Airborne Sensors (visible spectrum, multi-spectral) - Aerial Photography/Photogrammetry - Small Format Aerial Photography/Photogrammetry - Airborne Digital Video

The first stage in the sensor evaluation was to establish a minimum performance criterion that had to be met by the selected system. Technical issues to be addressed focused primarily on issues such as resolution, radiometric bands and acquisition/processing requirements. Sensors that did not meet minimum technical criterion were not assessed further. The process of sensor selection was by sequential elimination of those that did not meet the required objectives.

Sensor Technical Summary The technical specifications of the various sensor systems have not been detailed in this report. References to review the detailed specifications are listed in Table 2. The details of the relevant technical specifications for each system, as appropriate to the assessment of functional habitat are presented in Table 3. Actual wavelengths for the spectral ranges are available in the reference documents.

6 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Table 2. References providing technical details on each sensor system. Sensor Technical Reference Landsat 7 www.geoimage.com.au www.landsat7.usgs.gov/technical.html SPOT 4 www.geoimage.com.au www.spotimage.fr/home SPOT 5 www.geoimage.com.au www.spotimage.fr/home www.infoterraglobal.com/spot.htm Ikonos www.geoimage.com.au www.infoterra-global.com/ikonos.htm Quickbird www.digitalglobe.com www.infoterra-global.com/ikonos.htm IRS www.infoterra-global.com/irs.htm Aster www.infoterra-global.com/aster.htm Radarsat 1 / www.rsi.ca www.infoterra-global.com/radarsat.htm Radarsat 2 Envisat www.envisat.esa.int www.infoterra-global.com/envisat.htm

Table 3. Relevant technical specifications for each system as appropriate to the assessment of functional habitats. Actual wavelengths for the spectral ranges are available in the reference documents (Table 2). Sensor Resolution Spectral Range Coverage Landsat 7 15m panchromatic Blue, green, red, near 185km x 175km 30m multispectral infra-red, infra-red, thermal infra-red, near infra-red, green to near infra-red. SPOT 4 10m panchromatic Green, red, near infra- 60km swath 20m multispectral red, middle infra-red. (60km x 60km scene) SPOT 5 5m panchromatic Green, red, near infra- 60km swath 10m multispectral red, middle infra-red. (60km x 60km scene) (2.5m and 5m if the dual sensor images are combined) Ikonos 1m panchromatic Blue, green, red, near 11km swath 4m multispectral infra-red. Quickbird 0.61m panchromatic Blue, green, red, near 16.5km swath 2.44m multispectral infra-red. IRS 23m visible / NIR Green, red, near infra- 70km swath red, middle infra-red. (70km x 70km scene) Aster 15m visible / NIR Green, red, near infra- 60km swath red. (60km x 60km scene) Radarsat 1 8m fine mode 1 polarisation, single 50km x 50km fine, 25m standard mode band 100km x 100km standard Radarsat 2 3m fine mode 3 polarisation modes 50km x 50km fine, 100km x 100km standard Envisat 30m image mode Alternating polarisation 100km swath Sensor Resolution Spectral Range Coverage Aerial Photography 0.1m + Blue, green, red. Dependent on (dependent on image photographic scale. scale and scan resolution) Small Format Aerial 0.1m + Blue, green, red. Dependent on Photography (dependent on image photographic scale. scale and scan resolution) Digital Photography / 1.0m + (dependent on Blue, green, red. Dependent on Video image scale) photographic scale.

7 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Sensor Technical Evaluation In mapping functional habitat, the primary objective is to ensure that the input imagery is of sufficient resolution to detect the functional habitat units. The issue of radiometric range is of less significance, as the analysis will be primarily on feature recognition as opposed to classification of zones based on radiometric response. Although radiometric bands into the infra-red spectrum will enhance interpretation, this is not as important as is the issue of resolution. As all proposed systems (excluding the SAR systems) meet requirements with respect to radiometry and coverage, the following assessment focused on the issue of resolution. The radiometry of the SAR sensors was assessed in conjunction with resolution.

There are fundamentally three classes of sensor as a function of image resolution (refer Table 3). These are the low-resolution satellite sensors (Landsat 7, SPOT 4, IRS, Aster, Radarsat 1, and Envisat), the high-resolution satellite sensors (SPOT 5, Ikonos, Quickbird and Radarsat 2) and the airborne sensors. Evaluation of all three classes of sensors is outlined below.

° Low-Resolution Satellite Sensors Figures 1 and 2 show the expected image resolution for the Landsat 7 and SPOT 4 satellites respectively. As can be seen from the zoomed images, the resolution on a river system comparable to that of the Ord, does not enable extraction of functional habitat units such as backwaters, bank extent or snags. As such, the low-resolution Landsat 7, SPOT 4, IRS and Aster sensors were not considered further as candidates for this project.

Figure 1. Example of resolution achieved with Landsat 7 satellite images - 30m image resolution.

8 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 2. Example of resolution achieved with SPOT 4 satellite images– 20m image resolution.

Figure 3 shows a Synthetic Aperture Radar output in a river reach consistent with that above. The radar image is at a 10m resolution, which is consistent with the resolution of the Radarsat 1 system. Although features such as small tributaries can readily be identified, the majority of functional habitat units are either not identifiable or are ambiguous.

Figure 3. Example of Synthetic Aperture Radar (SAR) image – 10m image resolution.

9 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

The Radarsat 1, Radarsat 2 and Envisat sensors were not considered further as candidates for the current project on the basis of both image resolution and radiometry.

° High-Resolution Satellite Sensors The high-resolution SPOT 5 satellite sensor, with 10m multispectral and 5m combined multispectral, was outside the limit of resolution acceptability and therefore not considered suitable for the requirements of the current project.

Due to the prohibitive costs associated with tasking a once-off request of a small area for this assessment, samples of other high-resolution satellite images were not acquired for the analysis undertaken in this evaluation report, but simulated imagery was generated with resolution and radiometry comparable to the high-resolution systems.

Figures 4 and 5 show simulated multispectral imagery from the Quickbird (2.44m resolution) and Ikonos (4.0m resolution) satellite systems respectively. In both cases, the principal functional habitat units could be identified, although identification on the Ikonos 4.0m imagery was approaching the outer bounds of reliability. However, both the Ikonos and Quickbird sensors were acceptable, in terms of sensor performance and output image specification, for consideration as target platforms for the acquisition of imagery in the current project.

Figure 4. Example of simulated multispectral imagery from Quickbird satellite system – 2.44m image resolution.

10 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 5. Example of simulated multispectral imagery from Ikonos satellite system – 4.0m image resolution.

° Airborne Sensors The evaluation of the airborne sensors (film and digital camera systems) was undertaken on the basis of scanned imagery at 0.2m and 1.0m resolutions for film, and 2.5m resolution for digital. The imagery of Figure 6 shows the comparison between scanned high-resolution film-based aerial imagery and simulated 1.0m panchromatic and 4.0m multispectral Ikonos satellite imagery. The resolution of the digital airborne system (2.5m resolution) would be similar to the Quickbird imagery (2.44m image resolution) as shown in Figure 4.

Although resolutions better than 2.5m could be readily achieved for digital airborne imagery, this was estimated as the optimal resolution with consideration of image coverage. In order to achieve higher resolution, there would be a need to mosaic several images normal to the river in order to acquire complete coverage. This would be a difficult and time consuming task which would negate any benefit that the technique offers. Scanned imagery from film-based systems does not suffer from the resolution verses coverage conflict and it would be possible to acquire imagery with resolutions ranging from 0.2m as a function of camera system and film scanner utilised. Image resolutions for the scanned film option are shown in Figure 6 (0.2m airborne) and Figure 7. In both cases there was very good identification of the majority of functional habitat components.

11 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

0.2m Airborne 1.0m Panchromatic 4.0m Multispectral (Simulated Ikonos) (Simulated Ikonos)

Figure 6. Comparison between scanned high-resolution (0.2m) film-based aerial imagery and simulated panchromatic (1.0m resolution) and multispectral (4.0m resolution) Ikonos imagery.

Figure 7. Example of scanned film based aerial imagery – 1.0m image resolution.

12 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Acquisition / Processing Evaluation Based on the initial screening of sensors using resolution capabilities, a number of sensors were selected for further assessment of image acquisition and processing. These included the high-resolution satellite sensors (Ikonos and Quickbird) and the aerial photography options (full format aerial, small format aerial and digital aerial). Table 4 identifies the advantages and limitations of each proposed system. The processing component did not include a review of the extraction of the functional habitat components as this would be fundamentally the same for all imagery, independent of acquisition method. The processing assessment considered the processes required to produce a suitable image for analysis.

While the option of aerial digital photography offered some advantages in terms of ease and flexibility of image acquisition, the method was not considered suitable to survey extensive areas such as the entire ~70km reach of the lower Ord. This was due to the envisaged complexity of image processing. If the method was to be utilised only over shorter, replicate reaches of several kilometres (the approach taken for the Phase II field trial), the method would have significant advantages. However, for the implementation over the whole of the lower Ord River, there was a high probability that the complexity of image processing would mean that image technical specifications were not met.

The high resolution satellite systems (Ikonos and Quickbird) offered significant advantages in terms of acquisition and processing compared to the film-based photographic systems when applied to the whole lower Ord. However, because of the relatively large minimum acquisition area, the same costs still applied for application to multiple shorter reaches, as the whole region needed to be acquired. The film-based systems had the potential for significantly higher image resolutions and hence improved reliability in the extraction of functional habitat components. In addition, they offered flexibility with the ability to vary image output to suit analysis requirements. Images could be designed on a needs basis with respect to radiometry (panchromatic or multispectral) and resolution. Depending upon the method of application (replicate reaches versus whole of lower Ord River) there were not clear benefits of one approach over the other. Therefore, both the high-resolution satellite systems and the film-based photographic systems were further assessed with respect to acquisition and processing cost.

Acquisition / Processing Cost Acquisition and processing cost were estimated for the Ikonos, Quickbird, aerial photographic and small format aerial photographic options. The costs did not include the analysis of the imagery to extract the functional habitat components nor did they include DoE costs in managing the project. The tabulated costs should not be used to budget options, as there will be significant variations depending on contractors used, area of coverage and required accuracy. The costs derived have been done consistently to enable comparison of methodologies only. Table 5 details the estimated costs for the acquisition of imagery from the sensors defined in Table 4.

13 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Table 4. Satellite and aerial photography systems further assessed for image acquisition and processing.

Sensor Acquisition Processing/Image Analysis Satellite Ikonos Order through an authorised agent, The image supplied would be a supplying bounds of the area required seamless coverage of the defined area. (minimum width 5km, minimum area It is possible that several strips would 100 km2 or 49km2 if on archive). need to be de-referenced and mosaiced. Cloud cover is ≤20%. Accurate georeferencing would require ground control survey or registration against existing maps. Quickbird Order through an authorised agent, The image supplied would be a supplying bounds of the area required seamless coverage of the defined area. (minimum width 5km, minimum area It is possible that several strips would 64 km2 or 25km2 if on archive). Cloud need to be georeferenced and mosaiced. cover is ≤20%. Accurate georeferencing would require ground control survey or registration against existing maps. Aerial Photography Aerial Photography Contract a photogrammetric firm to The film would need to be scanned and (Film) acquire imagery. The combination of triangulated, processes undertaken by image scale and scanning resolution skilled photogrammetric operators. would be defined to give the required Georeferencing in the triangulation digital resolution. phase would be by using ground survey or with respect to existing mapping. Image mosaicing to form a seamless coverage would be relatively easy based on the available inputs. Small Format Aerial Establish a technical and equipment The film would need to be scanned and Photography (Film) capability to acquire imagery as triangulated, processes undertaken by required. Camera systems such as skilled photogrammetric operators. calibrated Hasselblad film cameras Triangulation complexity would be would be suitable. Image acquisition higher than the aerial full format option would be similar to the aerial due to reduced control of camera photographic case; however increased orientation in the acquisition phase. flexibility in acquisition and timing Georeferencing in the triangulation would be evident. If the image phase would be by using ground survey acquisition was undertaken by DoE or with respect to existing mapping. then there would be a substantial Image mosaicing to form a seamless increase in project logistics (equipment, coverage would be more difficult than aircraft hire, flight planning). the aerial full format option due to an estimated 2 to 4 times the number of input images. Aerial Digital Establish a technical and equipment The input images would need to be Photography capability to acquire digital imagery as rectified and mosaiced to form a required. Camera systems such as seamless image for analysis. It is calibrated digital and digital video expected that the number of images to cameras could be utilised. Camera be processed will be large (>100) for system selected would require the coverage of the Ord study area. As consideration of required output a function of required accuracy the resolution and coverage to ensure the provision of survey control and the final product met technical implementation of the triangulation specifications. If the image acquisition process is expected to be significant. was undertaken by DoE then there would be a substantial increase in project logistics (equipment, aircraft hire, flight planning).

14 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Table 5. Estimated image acquisition costs for sensors listed in Table 4 above.

Sensor Activity Component Cost Total Cost

Ikonos Imagery 12,500 (4m multispectral) Mosaic / Ortho / Georeference 1,700 $14,200 Ikonos Imagery 22,400 (1m + 4m bundle) Mosaic / Ortho / Georeference 2,500 $24,900 Quickbird Imagery 16,900 (2.4m multispectral) Mosaic / Ortho / Georeference 1,700 $18,600 Quickbird Imagery 22,600 (0.6m + 2.4m bundle) Mosaic / Ortho / Georeference 2,500 $25,100 Aerial Photography Photography (including film and 4,000 processing) 1:20,000 scale Ferry 10,000 Triangulation / Image Registration 6,000 Film Scanning 2,500 Image Mosaic / Ortho 7,500 $30,000 Small Format Photography (including film and 7,500 Photography (Analogue) processing) 1:20,000 scale Triangulation / Image Registration 14,000 Film Scanning 5,000 Image Mosaic / Ortho 10,000 $36,500 Small Format Photography 7,000 Photography (Digital) Triangulation / Image Registration 18,000 Image Mosaic / Ortho 12,000 $37,000

The above costs were based on the acquisition of suitable imagery over the whole of the lower Ord River (~70km in length). In estimating costs, it was assumed that: • the imagery, in the case of the satellite systems, would not be from archive and that the minimum width of image acquisition would be 5km, • in all cases the imagery would be referenced to existing mapping, • the aerial photography would be acquired at a photographic scale of 1:20,000 and scanned at 20 microns - this would yield an image resolution of 0.4m which could readily be re-sampled as required and • for small format photography, all work would be contracted by DoE and that all required equipment would be supplied by the contractor.

In assessing the estimated costs, the following factors were considered: • Both Ikonos and Quickbird satellite imagery were deemed suitable provided cloud cover was ≤20%. Although this could mean that river coverage was significantly reduced, it was also recognised that cloud cover is generally not an issue during the dry season in the Ord River region of Western Australia. • In the case of the aerial photography option, it is possible that an ‘in- conjunction’ photography mission can be arranged. Although this would not negate the $10,000 ferry estimate, it may mean that project costs would be reduced to around $25,000.

15 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

• Triangulation costs are linked to the quality and distribution of ground control. In the case of map derived control it is possible that triangulation costs may be 20 to 30% higher than those estimated.

Phase I Recommendations Based on the results of the technical and cost analyses, it was recommended that Quickbird (multispectral satellite) and aerial digital imagery be trialled as the remote sensing imagery for the analysis of functional habitat in the Ord River.

Although imagery derived from airborne systems offer higher resolution than the space borne systems, there was significantly higher technical and cost risk with the airborne imagery when applied to the whole of the lower Ord River as one reach. In addition, there was significantly higher management involvement with the airborne options that was incorporated into the estimated costs. However, aerial digital imagery provided greater resolution and flexibility than the satellite imagery and when applied at the replicated, shorter reach scale, may provide better mapping of functional habitats.

Risks associated with the acquisition of satellite imagery, primarily that of unacceptable cloud cover, were considered to be manageable; the time of year that imagery would be required (i.e. dry season when water levels are lowest) coincides with the lowest probability of cloud obstructing the imagery.

Although the Quickbird satellite imagery was 30% more expensive than the equivalent Ikonos satellite imagery, it was considered that the improvement in image resolution was worth the increased cost. It was believed that the Ikonos multispectral imagery (with 4.0m resolution) was at the limit of acceptability and on this basis the additional cost to improve resolution to 2.44m by using Quickbird was justified. In comparison to the airborne systems, the inclusion of an infra-red band would have some benefit in assessing vegetation communities bordering the river system. While the inclusion of the higher resolution panchromatic imagery as a bundle would have some benefit in interpretation, this benefit was not considered justified with respect to added cost.

Therefore, it was recommended that both the Quickbird multispectral imagery and aerial digital imagery be trialled over the short reach scale. The minimum Quickbird satellite coverage was 5km x 12.8km (64km2). This would allow two replicate reaches of approximately 5km length to be placed within a single Quickbird image. Aerial digital imagery could then be tailored to acquire the same reaches. Subsequently, these reaches would be ground-truthed to map habitats and thereby assess mapping effectiveness.

16 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

PHASE II - FUNCTIONAL HABITAT MAPPING TRIAL Approach Based on the recommendations of the Phase I evaluations, a small reach of the lower Ord River known to contain the suite of key habitat types identified by Storey (2002 & 2003) was selected as the location for the Functional Habitat Mapping Trial. The ‘Lower Reach’, defined in Figure 8, was selected as the site with proposed evaluation of both the Quickbird satellite imagery and airborne digital video imagery to be conducted in spring 2003. Available records of river discharge at the time of satellite and aerial image acquisition were sourced to enable standardisation of future mapping to the same stage height. Mean river discharge at the time of survey was approximately 80.4 m3.sec-1 (Figure 9).

Figure 8. Selected Reach for the Functional Habitat Mapping Trial

84 )

c 82 e s / 3 m (

e 80 g r a h c s i 78 D

76 27-Oct 28-Oct 29-Oct 30-Oct 31-Oct 1-Nov 2-Nov 3-Nov 4-Nov

Date

Figure 9. Ord River discharge (m3 sec-1, Tarrara Bar) at time of aerial survey and ground-truthing (1-3 Nov. 2003).

17 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Quickbird Satellite Image Acquisition Quickbird satellite imagery was booked in September 2003, however acquisition was unexpectedly delayed due to cloud cover exceeding the 20% threshold. Coverage was finally acquired over the lower Ord River on the 1st November 2003 and coincided with the date of aerial photography acquisition. This fortuitously minimised any temporal differences in images, water depths etc. The Quickbird imagery was pan-sharpened 8- bit colour imagery with a ground resolution of 0.000005 degrees. The geodetic datum of the supplied imagery was WGS-84. Four image tiles were supplied, covering the lower Ord River over an area within coordinates 15.523S, 128.472E (NW Corner) and 15.596S; 128.547E (SE Corner).

Figure 10 shows the acquired imagery covering the lower Ord River. Acquisition specifications were for rectangular coverage orientated from Carlton Crossing in a north-east direction. Supplied imagery however, was orientated in cardinal directions with some loss of coverage immediately downstream of Carlton Crossing. Figure 10 shows the extent and orientation of the commissioned Quickbird acquisition.

Figure 10. Extent and orientation of Quickbird imagery acquired for the lower Ord River, 1st November 2003. By comparison, the inset indicates the original rectangular coverage that was specified for acquisition imagery.

18 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

The Quickbird imagery was transformed with respect to a UTM projection from WGS84. Without the aid of differentially corrected geodetic control, the images were georeferenced with respect to the supplied Quickbird location data. Quickbird imagery was acquired at a ground resolution of 2.44 metres in multispectral mode and 0.61 metres in panchromatic mode. The image product selected was the pan-sharpened imagery, comprising a sharpening of the multispectral imagery from the panchromatic imagery. The resulting product was effectively a 0.61 metre resolution multispectral image, supplied as a RGB GeoTIFF image.

Digital Video Image Acquisition Digital video was also acquired over the area on the 1st November 2003. As this coincided with the acquisition of the Quickbird imagery, comparisons regarding image applicability for the task of defining functional habitat units were not biased due to climatic and radiometric variability.

Imagery was acquired using a commercial digital video camera with 3.0 x 106 pixel resolution. The Panasonic NV-MX500 3 CCD digital video camera used was an ‘off- the-shelf’ model with several distinct advantages for airborne image capture. These advantages included the capture of Red, Green and Blue radiometry via three distinct CCD sensors within the camera. In addition, the camera had the ability to capture high- resolution digital imagery directly to an SD card or images could be stored at video resolution on magnetic tape. Camera shutter speeds could be manually set to achieve the 1/500th second – 1/1000th second rate required. Figure 11 shows the camera used for the data acquisition and Table 6 details specifications.

Figure 11. Panasonic NV-MX500 digital video camera (inset) and position of mount on Cessna 206 aircraft.

19 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Initial digital acquisition at 1000 ft altitude was considered unacceptable because of high levels of atmospheric turbulence as a result of flying at midday (intentionally selected so that the sun was overhead to minimise shadow) and the inability to keep the aircraft centrally over the river channel without being able to see the channel immediately below (i.e. difficulties with narrow field of view relative to channel width) made accurate acquisition difficult. Digital imagery was subsequently acquired at an altitude of approximately 2,000 feet1 (609.6 metres) with the camera mounted from the foot-step of a Cessna 206 aircraft.

Table 6. General Digital Video Camera Specifications for Habitat Mapping.

Function General Specification Mode Digital Lens Glass Lens; typically Zeiss, Schneider, Leica, Rollei. Calibration The lens should be calibrated for radial and tangential distortion. The image chip should be calibrated for sensor distortions. (Only required for monitoring applications where accurate image mosaicing and image geo- referencing is required). Aperture Settings Manual over-ride required, with aperture of F2.8 to F16 and shutter speed minimum of 1/1000th sec. Image Capture Both digital tape (video) and digital card (image still) recording. Image resolution should be better the 3.0 x 106 pixels. Make sure that card record time does not exceed 5 to 7 seconds; to achieve this image resolution may need to be sacrificed. Sensor Preference is for three individual CCD sensors; one each dedicated to the Red, Green and Blue spectrums. An interlaced sensor with R, G, B recording can be used but does not give as good radiometric recovery. Battery Life Operation for a minimum of 2 hours in record mode without the need for battery change. This will be more critical for configurations where the battery cannot be changed in-flight. Remote Control An IR remote and (if possible) a free-style remote. The free-style remote will be critical in cases where the camera mount precludes access to the IR receiver. For an IR remote only, the camera mount and external camera configuration becomes critical. Remote Control The remote should be able to start, stop and record both digital still and digital video modes. A change in mode between digital card and digital tape recording is an advantage. Output Image Format An option to output raw images (i.e. uncompressed) is an advantage if critical variances in image radiometry are expected. Compression (e.g. JPEG) is acceptable with options to vary image compression quality. Digital Card The digital memory card should be able to store a minimum of 50 uncompressed images. Verify that image record time does not degrade with increased memory size on the card. General Options Facility to: - turn off sound, - turn off / activate image stabiliser functions, - facility to quickly download images (USB 2.0 or Firewire) and - flexible image capture software (digital stills from either card or tape).

1 Feet are the standard unit used to measure aircraft altitude.

20 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Any future programmes utilising similar equipment configuration would require a rigid camera mount and an in-cockpit video link to aid with navigation, whereby the pilot may view the actual area ‘seen’ by the camera and ensure adequate channel coverage.

Image positioning was undertaken using a GPS without differential input. A Garmin Map76S was used to track the flight path and the images were referenced to position using time synchronised on both the digital camera and the GPS sensor. Figure 12 shows the track from Kununurra and the image acquisition epochs in the vicinity of the study area.

Images were acquired from both the high resolution SD card data set and captured from the magnetic tape. A sample image with an output resolution of 0.5 metres is shown in Figure 13.

For the reach between Carlton Crossing and Macca’s Barra Camp (adjacent to House Roof Hill), images were captured, georeferenced and mosaiced. The resulting image mosaic is shown in Figure 14. Image mosaicing was undertaken using the ENVI software package, with georeferencing based on the GPS centroid positions measured during flight and with image-to-image constraints. There were significant shifts in image location due to the instability of the selected camera mount on the aircraft and any future data acquisition programmes would require the fabrication of a rigid mount on the aircraft. At an altitude of 2,000 feet (609.6 m) above ground level, the coverage of the river floodplain was limited. Future data acquisition programmes should be undertaken at an altitude approaching 4,000 feet (1,219.2 m) above ground level. While this would push the ground sampling distance out to 1.0 metre it is not envisaged that this would have any significant impact on habitat recognition or mapping. The benefit would be that navigation tolerances would be lower and approximately twice the surrounding river floodplain would be covered.

Figure 15 shows the results of the mosaicing process in terms of both radiometric and spatial accuracy. Spatial positioning has high precision, due to the nature of the image- to-image mosaicing process adopted, however absolute accuracy is a function of the accuracy of the GPS positions recorded during flight. It was estimated that absolute positioning accuracy was between five to ten metres with the ‘selective availability’ function of the GPS in the ‘off’ position. Improvements in absolute accuracy could readily be achieved through the use of differential GPS or identifiable ground control.

Radiometric balance was maintained across the images however, there was some imbalance at the image joins due to the vignetting process. Images acquired at a higher frequency, effectively removing the image edges from the mosaicing process, would reduce the effect of radiometric imbalance.

21 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 12. Digital video flight path – 1st November 2003.

Figure 13. Sample digital video image of lower Ord River taken 1st November 2003 with an output resolution of 0.5 metres.

22 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 14. Mosaic of digital video images of reach between Carlton Crossing and Macca’s Barra Camp (adjacent to House Roof Hill) taken 1st November 2003.

23 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 15. Results of the mosaicing process in terms of both radiometric and spatial accuracy. Absolute positioning accuracy was considered to be 5-10 metres. Some radiometric imbalance is evident at the image joins due to the vignetting process.

Image Classification Both the Quickbird and Digital Video images were classified using the ENVI remote sensing and image analysis programme. The image classification process employed two levels of classification; primary classification and full-classification. Table 7 defines the physical features for which classification was required, corresponding to the functional habitats of Storey (2002 & 2003). Tables 8 and 9 define the functional habitats of high importance respectively to invertebrate faunas and fish in the lower Ord River, downstream of the KDD, with equivalent remote sensing units. The physical and remote sensing units in these tables were the theoretical units upon which initial classifications were based.

To aid the classification process, a ground-truthing programme was incorporated into the field programme. This was undertaken on the 2nd and 3rd November 2003 and involved the identification of the physical units in Table 7, along with spatial location on the ground. Oblique photography was acquired to aid the classification process. Plates 13 - 29 illustrate field verification of physical units identified from remote sensing. The ground-truthing programme was limited to habitats along the main channel and no assessment was undertaken of the floodplain habitat types.

24 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Verification of final classification output will be required within the Ord River floodplain to confirm classification of habitat extents within the flooded riparian zone.

Table 7. Physical units identifiable from imagery. Physical Units to be Classified 1 Phragmites 2 Typha 3 Gravel/Cobble runs/bars 4 Boulder/ Whitewater rapids 5 Ribbonweed beds (submerged & floating) 6 Sandy margins along waters edge 7 Sesbania (high frequency inundation) 8 Melaleuca (high frequency inundation) 9 Eucalypts (low frequency inundation) 10 Snags (distinct units of large woody debris) 11 Backwaters (by morphology) 12 Deep/Open water (no vegetation)

Table 8. Functional habitats of high importance to invertebrate faunas (compare with Table 1, p.3) in the lower Ord River, downstream of the Kununurra Diversion Dam, with equivalent remote sensing units.

Invertebrate Units from Remote Sensing Emergent macrophyte 1 & 2 Phragmites & Typha (mapped separately and also combined for total area) Gravel runs 3 Gravel runs/bars Rapids 4 Boulder/Whitewater rapids Submerged macrophtyes 5 Ribbonweed beds Edge sand banks 6 Sandy margins along waters edge Deposits of mud and silt -- No unit applicable Flooded riparian – high frequency of 7 & 8 Melaleuca & Sesbania combined inundation (high frequency of inundation) Flooded riparian – low frequency of 9 Eucalypts on higher banks inundation (low frequency of inundation) Large Woody Debris 10 Snags

Table 9. Functional habitats of high importance to fish (compare with Table 1, p.3) in the lower Ord River, downstream of the Kununurra Diversion Dam, with equivalent remote sensing units.

Fish Units from Remote Sensing Emergent macrophyte 1 & 2 Phragmites & Typha (mapped separately and also combined for total area) Gravel runs 3 Gravel runs/bars Rapids 4 Cobble/Boulder rapids Submerged macrophtyes 5 Ribbonweed beds Flooded riparian – high frequency of 7 & 8 Melaleuca & Sesbania inundation (high frequency of inundation) Flooded riparian – low frequency of 9 Eucalypts inundation (low frequency of inundation) Snags/submerged woody debris 10 Snags/emergent woody debris Shallow backwaters 11 Define on morphology – physical shape of backwaters Deep backwaters -- N/A – wet season only Pools (deeper areas, > 2 m2) 12 Deep water areas Floodplain lagoons -- N/A – wet season only and off-river

25 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Plate 13. Submerged Ribbonweed (Vallisneria Plate 14. Eucalyptus spp. with scattered Melaleuca americana) bed – remote sensing unit #5 in Table 6. spp., along a steep river bank – remote sensing unit #9 in Table 6.

Plate 15. Large woody debris (snags; remote Plate 16. Emergent macrophyte (Typha sp.) at the sensing unit #10) with emergent macrophyte (Typha entrance to a small backwater zone – remote sp.; remote sensing unit #2 ) in the background. sensing unit #2.

Plate 17. Flooded riparian vegetation habitat (snags) Plate 18. Inundated backwater (unit #11) with the – remote sensing unit #10 in Table 6. entrance colonized by emergent macrophyte (Typha sp., unit#2), with submerged Ribbonweed (unit #5) in the foreground. Silver Cadjebut (Melaleuca argentea), Pandanus sp. and Freshwater Mangrove (Barringtonia arcutangula) line bank..

26 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Plate 19. Inundated backwater zone (unit #11). Plate 20. Shallow backwater (unit #11), with floating Ribbonweed (unit #5) across the mouth.

Plate 21. Exposed sand bank (unit #6) with isolated Plate 22. Extensive dead vegetation on an exposed dead vegetation and snags (unit #10). sand bar (unit #6).

Plate11. Carlton Crossing showing gravel run Plate 23. Rapids downstream of Carlton Crossing habitat (unit #3). (unit #4).

27 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Plate 24. Exposed gravel bed (unit #3) with the Plate 25. Emergent macrophyte (Typha; unit #2) initial colonization of exposed macrophyte. Riparian with floating Ribbonweed beds (unit #5) in the forest (Melaleuca spp. and Sesbania sp.; units #7 & foreground. 8) occupies the adjacent bank.

Plate 26. Small open backwater (unit #11) with Plate 27. Steep bank adjacent to the river with exposed snags (unit #10) on the surrounding sparse Melaleuca spp. and Eucalyptus spp. (units sandbank. #8 & 9).

Plate 28. Riparian vegetation on a small island Plate 29. Small colony of Typha on an exposed overgrown with Phragmites karka and Passiflora sandbar (unit #2). foetida (Passion Vine) (unit #1).

28 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

In the primary classification, the software image correlation process (using ENVI) defined regions that correlated with the radiometric responses for each habitat group. This process resulted in a complex pattern of habitat types across each zone. Figure 16 shows a typical scatter from the classification process compared with the classification image.

(a) (b)

Figure 16. Example of results of (a) primary classification of functional habitats using ENVI defined regions compared to (b) the source (Quickbird) image.

Based on the primary classification results, a full-classification was undertaken where the classification groups were vectorised into dominant habitat communities. In many cases, the habitats formed a complex mix within any single zone. For example, the riparian forest zone was typically not a discrete entity with well-defined boundaries, but in many cases, the emergent macrophytes and the eucalypt overstorey merged into the riparian vegetation zone. In such instances, the classification was based on the dominant habitat. In addition to the aerial classifications, this secondary phase identified point (snags and backwaters) and lineal features (sandy margins along the waters edge), classified on visual assessment rather than objective classification.

A full classification was undertaken on the Quickbird imagery (full scene) and on the Digital Video imagery for the reach between Macca’s Barra Camp and Carlton Crossing. Despite limited coverage of the floodplain vegetation communities, the classification of the Digital Video imagery was undertaken in order to compare the definition of functional habitats from both image sources. Results are shown in Figures 17 – 20. Figure 17 defines the legends for the classification images to follow as well as the classification units. The final vegetation transitions/vectors chosen for inclusion in any given classification unit were subjective, but were consistently applied to all data sets.

29 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 17. Habitat classification (full-classification) legend used for Quickbird satellite imagery (left) and Digital Video imagery (right).

30 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 18 shows the image classification as an overlay on the Quickbird satellite imagery for both the whole study site and detail in the vicinity of Carlton Crossing.

(a)

(b)

Figure 18. Results of full-classification of functional habitats for Quickbird image – (a) full scene results and (b) detail at Carlton Crossing (refer Figure 17 for classification legend).

31 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Figure 19 shows the whole classification from the Quickbird satellite imagery as the simple vector entities with no image base map, together with detail in the vicinity of Macca’s Barra Camp.

(a)

(b)

Figure 19. Results of habitat classification of Quickbird images shown as simple vector entities – (a) for the whole study area and (b) detail of the Ord River near Macca’s Barra Camp.

32 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

For the purposes of subsequent reporting, most images presented are from Quickbird classification as they provided more extensive coverage and were easier to manipulate than Digital Video. However, there were minimal differences between Quickbird and Digital Video platforms in terms of habitat classification results at the resolution of printed maps as illustrated in Figure 20, with actual differences in areal coverage only evident following computer analysis of respective classifications.

(a) (b)

Figure 20. Comparison of full-classification of functional habitats for (a) Quickbird image and (b) Digital Video image of the lower Ord River near Macca’s Barra Camp, demonstrating minimal visual difference at the resolution of the printed images.

.

33 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

COMPARISON OF IMAGING TECHNIQUES - Summary of Findings from Phase I & II Combined results from Phase I and II of the current project indicated both the Quickbird imagery and the Digital Video imagery to have unique benefits, but also definite disadvantages. These are discussed below.

Quickbird Quickbird high-resolution satellite imagery was by far the simplest and most cost effective method of acquiring imagery for the purpose of habitat assessment and mapping. Pan-sharpened imagery was acquired over coverage of approximately 60km2 (minimal unit coverage that can be acquired), for as little as $2,000. This imagery was georeferenced (to a level suitable for habitat mapping assessments) and was ready for image analysis with little or no intermediate processing.

The Quickbird imagery offered the best solution for the discrimination of habitat units on the historic floodplain due to the greater lateral coverage (i.e. kilometres either side of the channel). Despite being re-sampled from a 2.44m resolution image, the pan- sharpened data allowed for the discrimination of most habitat types on the historic floodplain with little ambiguity. However, this was not the case when assessing in- channel habitat or habitat immediately adjacent to the river. Three major deficiencies were evident: i. limited resolution for the discrimination of snags, ii. a high sensor “off-nadir” view angle means much of the habitat adjacent to the river or on the bank is missed and iii. limited penetration of the water for the definition of submerged macrophyte extent.

Figure 21 illustrates the difference between the Quickbird imagery and the Digital Video imagery with respect to snag definition. Only significant snags, possibly in the more complex arrangements, were identifiable in the Quickbird imagery. Snags that were clearly evident in the digital video image were not detectable in the Quickbird imagery. Assessing changes in ‘snag count’ from Quickbird imagery, and the consequences for habitat, would have low accuracy and reliability.

Quickbird acquisition was achieved with an off-nadir view angle of approximately 20 degrees. This oblique view angle means that at least one bank of the river was obstructed by the vegetation on the bank. In some cases this was severe enough to obstruct snags, riparian vegetation, sandy margins and submerged macrophyte beds. This is a significant disadvantage, given that much fish habitat is close to the bank. Figure 22 shows the extent of obstruction due to the high off-nadir view angle in the Quickbird imagery. Based on these results, the ideal angle would be between 5 – 10 degrees.

34 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

(a) (b)

Figure 21. Snag habitat (arrowed) captured as (a) Quickbird image and (b) Digital Video image. Refer Plate 17 for ground-truthing photo of snag habitat.

Figure 22. Quickbird satellite imagery illustrating impact of high off-nadir view angle.

35 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

It is possible to obtain Quickbird images with lower off-nadir view angles. Quickbird offer options to acquire imagery at two off-nadir ranges; 0 - 25 degrees (standard) and 0 - 15 degrees (special request). However, if imagery were to be ordered at 0 – 15 degrees there would be no guarantee that the maximum 5 – 10 degrees would be achieved. In addition significant time delays are possible with the special request. The frequency of passes by the satellite with this nadir is less and therefore it may take longer (i.e. several months) to obtain images allowing for cloud cover etc. Images with lower degrees off-nadir can be specifically tasked, however tasking Quickbird flights incurs substantial additional cost. Although acquisition costs may be higher and acquisition time significantly extended, any future Quickbird data sets should be acquired within a range of 5 - 10 degrees off-nadir.

Possibly the biggest problem with the Quickbird imagery was the radiometric penetration beneath the water surface. Submerged macrophyte extent was difficult to extract and had low reliability, particularly in zones where the radiometric response of deep water was similar to that of submerged ribbonweed. Although a full pan- sharpened image with a composite spectral range of red, green, blue and near infra-red (NIR) was ordered, the image supplied was a three-band composite of the four available bands, with the NIR-band included. Figure 23 shows a single Digital Video scene inter-cut into the corresponding Quickbird scene to demonstrate the difference in degree of water penetration between the two sensors, with water penetration obvious for the Digital versus the Quickbird imagery. The water appears dark in the Quickbird image due to the absorption of energy in the visible red and NIR bands. It is recommended that future analysis is undertaken on a four-band (R,G,B & NIR) separated GeoTIFF image, with the NIR band excluded for optimum water penetration.

Figure 23. Comparison of water penetration characteristics of a reach coverage of Quickbird satellite sensor (pan-sharpened image without NIR) compared to a single Digital Video scene inter-cut into the corresponding Quickbird scene (overlay). 36 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

In order to analyse the Quickbird imagery a degree of image analysis needed to be undertaken. This processing aimed to enhance the water penetration capabilities of the Quickbird imagery by passing enhancement filters over the region of interest. Figure 24 shows a comparison of the Quickbird imagery before and after image enhancement. Although submerged macrophyte colonies could be identified, this was limited to shallower water and small colonies were readily missed.

(a) (b)

Figure 24. (a) Quickbird source image and (b) same image with enhancement filters.

Similarly, Figure 25 presents image classification results from un-enhanced and enhanced images for the same river reach as shown in Figure 23, allowing direct comparison of ‘enhanced’ water penetration.

Figure 25. Classification results from un-enhanced and enhanced Quickbird satellite images.

37 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Digital Video Digital Video imagery was demonstrably superior to the Quickbird satellite imagery for the following technical reasons: 1. With nadir acquisition and a narrow view angle, any problems associated with off- nadir obstruction were negated. 2. Image resolution could be varied as a function of the type of habitat that required discrimination. At a similar resolution to the Quickbird imagery, the Digital Video gave superior feature discrimination and definition. 3. Digital Video sensor provided high quality radiometric definition below water. No image enhancements were required and both small and isolated habitat groups were readily identifiable in the imagery.

The major deficiencies with the Digital Video pertained to coverage, cost of acquisition and image processing: • The coverage of the Digital Video image, at the 2,000 feet altitude employed in this trial, was at the limit of acceptable lateral coverage for the historic floodplain, but gave almost acceptable coverage for in-channel habitats. A combination of bracket movement and the difficulty of keeping the aircraft directly over the channel without an in-cockpit monitor resulted in poor coverage of large sections of the historic floodplain (though only small areas of in-channel habitat were missed). Additional imaging runs would need to be undertaken to ensure complete coverage of the historic floodplain. However, the need for wider coverage of the floodplain is debatable, since the river is now confined within the channel due to regulation and seldom floods the historical ‘bankfull’ floodplain. Critical in-channel areas that were missed were mostly on the insides of meander bends where the river may flood to several hundred metres wide in the wet season. With an increase in flying height to 4,000 feet, the corresponding ground resolution would be approximately 1.0m and the coverage doubled, providing total coverage of the in-channel habitats. It is not envisaged that the reduced resolution would have any impact on habitat assessment and is recommended as the optimal combination for any future habitat mapping programmes. • Image acquisition costs can be high, and need to include aircraft hire, equipment and mount purchases, personnel costs and travel costs. Costs were estimated to be 2 - 3 times that of the basic Quickbird acquisition costs (though tasking Quickbird would increase costs). • Image mosaicing and georeferencing can be time consuming and requires skilled operators. It was estimated that half an hour per image would be required to georeference, colour balance and insert into a mosaic. For a reach of 20 images, this would equate to approximately 10 hours work prior to any classification being undertaken. The cost for such analysis, including purchase of mosaicing and image processing software, should be included in any final method recommendation.

38 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Aerial Coverage of Habitats The aim of the Functional Habitat mapping was to provide remote sensor coverage (i.e. aerial coverage) of each habitat in specified reaches in order to monitor temporal changes. Ideally, representative reaches would be selected and routinely mapped on a regular basis to assess temporal changes. To demonstrate the ability of the remote sensing platforms/classifications to provide aerial coverage, the area of each physical unit between Carlton Crossing and Macca’s Barra Camp was estimated for each platform (refer Table 10). Differences in area estimates between the two platforms are also discussed in Table 10, however the main points to note were: • The Digital Video did not provide total in-channel coverage due to bracket movement and flight path inaccuracy. As such, areas of extreme lateral habitats were under-estimated (viz. area of low-frequency inundation eucalypts on the higher banks and high-frequency inundation Melaleuca/Sesbania vegetation on the low benches); • The area of in-channel habitats was likely underestimated by Quickbird due to limitations related to the vertical penetration of the water column and effects of 20 degrees off-nadir.

It should be noted that the area estimates were preliminary and must be viewed with caution. Pre-classification ground-truthing was used to train the classification to recognize specific examples of each physical unit. However, post-classification ground-truthing is needed to confirm the ability of the method to correctly classify physical features outside of the area of original ground-truthing.

39 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Table 10. Aerial coverage of each physical habitat unit between Carlton Crossing and Macca’s Barra Camp (House Roof Hill) as calculated from classifications of Quickbird satellite and Digital Video imagery.

Area estimates (m2) are given for most classification units except backwaters and snags, which were estimated by abundance (number/count) and sandy margins, which were estimated by length (m).

Classification Unit Quickbird Digital Video Comments Preference Rapids 0 m2 850 m2 Rapids did not appear at all on the Quickbird imagery. The extent and Digital Video definition on the Digital Video was adequate.

Backwaters 25 27 Backwaters were readily discernable on both Quickbird and Digital Either Video imagery. Obstructions due to off-nadir viewing obscured some backwaters in the Quickbird imagery.

Submerged macrophtyes 254,700 m2 244,040 m2 Although the results are within 4%, the Digital Video offers superior Digital Video (submerged Ribbonweed beds) water penetration and Ribbonweed beds are readily discernable. Quickbird imagery had very poor water penetration characteristics and Ribbonweed bed radiometry was similar to that of deep water zones. However, this limitation may be overcome by removing the near infra- red band into the pan-sharpened Quickbird images.

Submerged macrophtyes 23,520 m2 32,940 m2 Approximately 5,370 m2 of floating Ribbonweed was incorrectly Digital Video (floating Ribbonweed beds) classified as Typha sp. in the Quickbird imagery. The radiometry and texture of Typha sp. in the Digital Video imagery offers unambiguous classification for large communities.

Emergent macrophyte 11,190 m2 6,570 m2 See classification error above. The radiometry and texture of Typha sp. Digital Video (Typha spp.) in the Digital Video imagery offers unambiguous classification for large communities as opposed to the Quickbird platform.

Emergent macrophyte 7,170 m2 7,170 m2 The agreement between the classification areas of the two images is not Digital Video (Phragmites karka) an indication of classification accuracy. Both types of imagery give adequate results with classification accuracy estimated to be within several percent of actual.

40 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Classification Unit Quickbird Digital Video Comments Preference Snags/submerged woody debris 335 510 Based on adjusted nominal resolution the resolution of the Quickbird Digital Video pan-sharpened imagery was 0.7 metres derived from a 2.8 metre resolution multispectral image. It was evident that many of the smaller snags and smaller features were not detected by the sensor. In addition several snags were identified in the vicinity of Macca’s Barra Camp that were in reality part of the gravel rapids in the area. The final resolution of the Digital Video was 0.7 metres and at this resolution, the majority of snags were identified. There was some ambiguity in the case of complex snags or where the snags were close to the river bank.

Flooded riparian – high frequency of 764,730 m2 771,060 m2 Both the Quickbird image and the Digital Video image were suitable for Quickbird inundation the detection of the flooded riparian vegetation. There was some ambiguity in the demarcation between the riparian vegetation and the eucalypts/river gums, however this was not a function of the imagery but of the complex interface between the two regimes. The Quickbird imagery has significant advantages in terms of lateral coverage extent and hence the ability to readily cover the vegetation to the floodplain boundary.

Flooded riparian – low frequency of 282,800 m2 241,070 m2 See Above Quickbird inundation

Floodplain lagoons 26,420 m2 9,430 m2 Although the Quickbird imagery readily identified floodplain lagoons it Digital Video could not discriminate vegetation cover within the lagoon. In the Digital Video imagery, stands of Typha sp. and Phragmites sp. could readily be identified.

Sandy Margins 2,900 m 2,930 m Sandy margins were readily identifiable from both Quickbird and Digital Either Video imagery. In isolated cases, the effects of high off-nadir acquisition angles obstructed the edges of the river, however this was a minor issue.

41 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

CONCLUSIONS While there were significant limitations to the technical quality of the Quickbird imagery, particularly for some of the more important in-channel habitats (i.e. snags and macrophyte beds) it is feasible that several of these limitations may be addressed through modifications to the Quickbird acquisition methods. In the first instance, image acquisition should be restricted to within 5 - 10 degrees off-nadir to address the issues of off-nadir obstructions. Also, the NIR (near infra-red band) should be removed in the generation of the RGB (red, blue, green) image during the pan-sharpening process to enhance water penetration. If this substantially increases the ability of Quickbird imagery to classify and quantify habitats such as snags and macrophyte beds, this would make this platform comparable in performance to aerial video, otherwise, aerial video would be preferable.

Estimated acquisition and image analysis costs for the reach between Macca’s Camp and Carlton Crossing are given in Table 11. This assumes a minimum area for satellite acquisition of 12 x 5 km2, and an equivalent flight distance of ~ 12 km for acquisition of aerial digital imagery. Analysis estimates will vary as a function of image quality, image coverage and the quality of definition of habitat groups within each scene. It is expected that an additional cost of up to $500 may be incurred for geo-referencing and transformation of the recommended four-band imagery. Comparison of costs shows a cost saving for Quickbird over digital video, especially if the one-off equipment costs for establishing digital video capability are included (viz. camera = $3000, mount = $1000 and in-cockpit display = $1000; total = $5000). The logistical and cost limitations associated with the Digital Video platform are greater than the basic Quickbird satellite image acquisition set-up and may limit the frequency and extent to which this technique of habitat mapping can be applied. There is little doubt that the ease and simplicity of ordering satellite imagery has significant operational advantages. However, satellite acquisition costs will increase dramatically if specific tasking is required to achieve 5 - 10 degrees off-nadir. Also, for a design consisting of replicate ~ 5 km reaches dispersed along the lower Ord, satellite acquisition costs for total coverage of the lower Ord versus aircraft time to fly the replicate reaches will alter the cost comparison.

Suitability of Remote Sensors for Use in Other River Systems The Ord River seems particularly well suited to the application of remote sensing techniques (satellite or aerial photography) for mapping habitats for several reasons. These include a relatively wide river channel with large scale mesohabitats (metres to 10s of metres) that are distinguishable and distinct at the available levels of resolution, high water clarity (in dry season when habitat mapping would occur), minimal canopy cover over the water to obscure habitats, vegetation zonations equating to habitat types, with vegetation types distinguishable based on texture and colour, and a current active channel and floodplain occupying a narrow zone allowing image capture on single image runs. Systems with narrow channels, low water clarity, extensive and wide floodplains, indistinct zonation across habitat types, small scale habitat units below the level of resolution and extensive canopy cover obscuring in-stream habitats would minimize the effectiveness of these remote sensing techniques on other river systems. These issues would need to be assessed when considered application of these remote sensing approaches to other river systems.

42 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

RECOMMENDATIONS A recommended monitoring scenario and associated costs will depend to some extent on the area to be monitored, as there are economies of scale with each platform. Acquisition of a single satellite image at the minimum acquisition area (5 km x 12 km) will have cost efficiencies over acquiring digital aerial video over a 12 km reach of river. However, acquisition of a series of satellite images that will cover the whole of the lower Ord River will have substantial costs over flying a series of separate 5 km reaches dispersed along the length of the lower Ord.

Monitoring Scenario #1 If the optimum acquisition changes for the Quickbird imagery are possible, then the final recommendation would be to utilize each method optimally in a hybrid mode: 1. Acquire Quickbird imagery over the target site incorporating the acquisition modifications proposed (i.e. 5 - 10 degrees off-nadir & full pan-sharpened image). 2. Undertake a ground-truthing programme to enable image classification in the river, along the river margins and into the floodplain. 3. Undertake a selective Digital Video acquisition flight with emphasis on the main river channel and the immediate river banks. Although a GPS flight record is recommended, it is not essential as the Digital Video can be georeferenced with respect to the satellite imagery.

It is recommended that the primary classification and analysis be undertaken from the Quickbird imagery. In cases where off-nadir obstruction, water penetration or feature identification is limited then the relevant Digital Video scenes can be extracted and assessed. Assessment of both the ground-truthing information and the Digital Video images should be utilized during the classification of the Quickbird image. Such a proposal incorporates the inherent technical benefits of the Digital Video solution along with the extensive coverage and ease of acquisition of the Quickbird product.

Monitoring Scenario #2 If the optimum acquisition changes for the Quickbird imagery are not possible, then Digital video will be the preferred technique, using data acquisition at higher altitude (4,000 feet; 1,219.2m) and an in-cockpit monitor to allow better tracking of the channel. Purchase of in-cockpit monitor would incur a small once-off cost.

Monitoring Protocol Whichever technique is finally selected, the objective of any monitoring programme will be to estimate the aerial coverage and distribution of each habitat type under late dry season flows (i.e. minimum flow conditions that allow visual assessment of habitats). Initially, mapping will be conducted under the current dry season flow regime of approximately 60 m3.sec-1. Mapping under this regime should be repeated on at least three occasions, each occasion being a separate dry season, to provide an indication of between-year variability in habitats with mapping standardised to river stage height. Mapping may need to be repeated in the event of a large flood ‘resetting’ the system before the revised regime is implemented. The surveys will provide a ‘baseline’ data set against which changes in the distribution and aerial extent of each habitat may be tracked as the system adjusts to the altered flow regime. Subsequently,

43 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques these data will provide a baseline to assess any further change in habitats should a dry season flow scenario be implemented. Data obtained will be a combination of aerial coverage (km2) of each definable habitat and counts of individual habitats (i.e. snags).

To assist with future application of remote sensing to monitor functional habitats of the lower Ord River, the digital imagery acquired from satellite and video platforms during this study are included on a CD in the back cover of this report.

Table 11. Comparison of estimated acquisition and image analysis costs for the lower Ord River between Macca’s Camp and Carlton Crossing, based on 2003 costing, with salary rate of $800 per day.

Digital Video Platform Quickbird Platform Component Person days Cost Person days Cost Ground Truthing - field time 2 $1,600 $1,600 2 Boat/vehicle hire + fuel for ground $200 per day $200 $200 per day $200 truthing Aircraft Hire 3 hrs @ 345 $1,035 -- -- Scene Selection, Planning -- -- $400 0.5 Consumables (Data Storage) -- $200 -- -- Flight Planning 0.5 $400 -- -- Image Acquisition Costs 2 c $1,600 $2,000 -- Special Tasking of Satellite -- -- $2,000 -- Image Processing / Capture 2 $1,600 -- -- Image Mosaicing / Georeferencing 3 d $2,400 -- -- Georeferencing / Transformation -- -- $800 e 1 Primary Classification 2a $1,600 $1,600 2a Full Classification 3 b $2,400 $2,400 3b Reporting, Analysis, Transfer to GIS 2 $1,600 $1,600 2 Total $14,635 $12,600

Notes: a Primary classification duration will vary as a function of image quality, image resolution and habitat characteristics. This estimate is for habitat communities that are well defined and where radiometric characteristics allow unambiguous classification. b Full classification duration will vary as a function of the number of classification communities and as a function of the spatial complexity of each community. c Image acquisition duration will vary as a function of climatic conditions and required coverage extent. d Image georeferencing duration estimates indicated are based on an existing image / map defining spatial extent and location. e Additional costs to process a four-band (R,G,B,NIR) separated GeoTIFF are estimated to be $500.

44 Lower Ord River Functional Habitat Mapping: Evaluation and Field Trial of Remote Sensing & Imaging Techniques

Acknowledgments We would like to thank Slingair for their assistance whilst undertaking the aerial surveys. Staff at the DoE, Kununurra Office are thanked for their logistical support during ground-truthing, in particular Leith Bowyer, Scott Goodson, Mike Harris and Duncan Palmer. Kerry Trayler and Rob Donohue are thanked for their support during project management on behalf of the Department of Environment. Kerry Trayler is also thanked for constructive criticism of the draft report. Sue Creagh assisted with editing the final report.

References Storey, A.W. (2002) Lower Ord River: Invertebrate Habitat Survey. Final unpublished report to Water & Rivers Commission by Department of Zoology, The University of Western Australia, Perth. Pp 57.

Storey, A.W. (2003) Lower Ord River: Fish Habitat Survey. Draft Final unpublished report to Water & Rivers Commission by Department of Zoology, The University of Western Australia, Perth.

45