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Monitoring leaky landscapesWe all know leaky buckets aren't very useful, but what about leaky landscapes? A new index, developed through the Water for a Healthy Country Flagship, utilises high resolution remote sensing tools to help land managers monitor the health, or ‘leakiness', of grazed, arid and semiarid landscapes. Healthy and functional landscapes have a good cover of evenly dispersed perennial vegetation that retains and effectively utilises rain water. On rangelands of this type there is also little loss of plant nutrients in water-borne sediment, or wind-borne dust in dry times, as the vegetation reduces run-off and soil loss. Conversely, dysfunctional landscapes, which have low or patchy cover, have increased overland flow, in effect ‘leaking' water and nutrients to nearby streams. Hence, monitoring the leakiness of the land gives a good indicator of landscape health. Monitoring landscape health is important for adjusting land management practices, particularly stocking rate and wet-season spelling. Results can be used to analyse the effectiveness of selected management techniques and demonstrate the value of these techniques to relevant stakeholders. Traditional monitoring methods commonly measure a number of indicators of rangeland health at numerous field sites on the ground. However, the effort and time required to collect data in this way can be costly. This cost then limits the number of field sites and indicators that can be routinely monitored, and critical points of degradation in the landscape can be missed. To address this problem, a team of CSIRO scientists led by Dr John Ludwig, has developed the Leakiness Index to monitor landscapes at a broader and more thorough scale using remotely sensed (satellite) data. The method indicates the health of grazed landscapes based on their ‘leakiness'. This is an estimate of the potential for the landscape to leak soil sediments. Importantly, it does not predict or model the actual amounts of runoff and soil lost during storms, but provides a simple landscape assessment index. "Our aim was to develop a quantitative tool to remotely monitor the health of arid and semiarid landscapes," says CSIRO scientist, Gary Bastin. "This will allow land managers to detect changes in the relative condition or health of a site, or set or sites, over time." There are three inputs for the tool:
The Leakiness Calculator, a computer program developed by CSIRO's Dr Adam Liedloff, then calculates the relative leakiness of the analysis region. A high leakiness index (LI) value indicates a leaky, or unhealthy, landscape. The LI has been designed to be sensitive to the spatial patchiness of vegetation cover within landscape sites, and this was verified using sediment yield data collected from flumes at the bottom of paired sites located on a hillslope in the savanna rangelands near Charters Towers. "One of the other benefits about the index is that, by using the Landsat archive, we can make retrospective analysis of landscapes, so we can look at changes or trends over time," says Bastin. Using LI to monitor changes in landscape health has a number of applications. However, it has been particularly targeted to investigate the effectiveness of different management techniques. This could be beneficial at both paddock and catchment level to identify areas where particular attention is needed. Maps of potential landscape leakiness at large catchment scales would also be valuable for regional and national reporting of changes in rangeland health. For example, measuring land condition over broad areas at management-relevant scales could achieve improved grazing land management with respect to water quality in the Great Barrier Reef Catchments. Currently, through Water for a Healthy Country, the team are working closely with the Queensland Department of Primary Industries and Fisheries to assist them with improved methods for monitoring the condition of grazed rangelands in the Burdekin catchment. The LI has potential to be one of the key tools to support the land condition component of the Grazing Land Management package delivered to Queensland graziers. Future work includes further testing and ground validation of results in parts of the Burdekin and Fitzroy catchments, and tailoring the tool to assist rangeland monitoring agencies in other areas. More information: Contact: |
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| About this email This E-Newsletter uses an HTML-rich media format to provide an easy-to-follow, visually attractive layout. If for any reason, your computer does not support HTML format email, please let us know by emailing editor.healthycountry@csiro.au with your full name and email address, and we will ensure you receive our E-Newsletter in a plain-text format. Please feel free to forward it to those in your organisation who would be interested in receiving future newsletters. If you do not wish to receive this electronic newsletter from the Water for a Healthy Country Flagship, please reply to this message with the word "unsubscribe" in the subject line. Alternatively, please contact editor.healthycountry@csiro.au or telephone us on +61 2 6246 4565 to request the removal of your email address. This E-Newsletter is a publication of CSIRO. It does not purport to be comprehensive or to render professional advice. All material in this publication is subject to copyright. For permission to reproduce any part or all of an article, please contact the editor. |
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| Water for a Healthy Country Flagship CSIRO Editor: Leane Regan CSIRO Black Mountain Laboratories, Canberra, ACT, 2601 Phone: +61 2 6246 4565 Fax: +61 2 6246 5560 editor.healthycountry@csiro.au www.csiro.au/healthycountry/ |
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