Natural resource management issues in the Avon River basin

Analyses the risk of soil, land and water degradation within the Avon River Basin of Western Australia. Information is based on the interpretation of the characteristics of soils and landscapes within the Avon River basin. This report deals with 15 natural resource management issues and describes the extent of each issue, the impacts that each issue will have, management options that can be used to deal with each issue, and the effectiveness of each management option in dealing with the issues

Phillips Brook catchment appraisal

This report describes the soils, hydrology and natural vegetation of the Phillips Brook catchment near Toodyay, Western Australia and provides information on the threats to agriculture, infrastructure and natural resources from salinity, waterlogging, erosion and other land degradation processes

Agricultural sub-regions of the Avon River basin

This report identifies, describes and locates nine sub-regions within the land cleared for agricultural uses in the Avon River Basin in Western Australia. The sub-regions are: Darling Range; Dale/Upper Avon; Avon Valley; Yealering Lakes; Mortlock; Northern Sandplain; south-east Lakes; Carrabin; Southern Cross. The sub-regions are described in terms of their distinguishing biophysical characteristics of: soils and related original vegetative cover; general topography; surface and sub-surface hyrdological stus; underlying geology; and rainfall and evapotranspiration range. Current dominant land use, economic drivers and land use pressures are identified for each sub-region

Optimizing the roles of unit and non-unit protection methods within DC microgrids

The characteristic behavior of physically compact, multiterminal dc networks under electrical fault conditions can produce demanding protection requirements. This represents a significant barrier to more widespread adoption of dc power distribution for microgrid applications. Protection schemes have been proposed within literature for such networks based around the use of non-unit protection methods. This paper shows however that there are severe limitations to the effectiveness of such schemes when employed for more complex microgrid network architectures. Even current differential schemes, which offer a more effective, though costly, protection solution, must be carefully designed to meet the design requirements resulting from the unique fault characteristics of dc microgrids. This paper presents a detailed analysis of dc microgrid behavior under fault conditions, illustrating the challenging protection requirements and demonstrating the shortcomings of non-unit approaches for these applications. Whilst the performance requirements for the effective operation of differential schemes in dc microgrids are shown to be stringent, the authors show how these may be met using COTS technologies. The culmination of this work is the proposal of a flexible protection scheme design framework for dc microgrid applications which enables the required levels of fault discrimination to be achieved whilst minimizing the associated installation costs

Esperance area acid sulfate soil hazard mapping

This project created a regional scale (1:100 000) acid sulfate soil (ASS) hazard map for the Lake Warden and Esperance town areas, using a combination of existing soil-landscape mapping information and elevation data, supported by field observations and laboratory data from 18 soil cores and 29 additional borelogs with descriptive information useful for identifying ASS and potential ASS materials. All data gathered during this project used common standards and protocols developed in Australia for identifying and mapping ASS materials. The project extends the mapping for acid sulfate soil in the region, complementing existing maps compiled for other parts of the state. This map should be used in conjunction with protocols developed by the Department of Environment and Conservation for the management of acid sulfate soil materials. The resulting hazard map classifies the landscape according to the probability of intercepting ASS materials within the top 6m of regolith. A three-class rating is used: ‘high probability of occurrence’, ‘low probability of occurrence, ‘very low probability of occurrence’, commonly used on regional-scale ASS hazard maps in Australia. This scale of mapping is only suitable to signal the need for further assessment prior to land development involving excavation and/or drainage. Management decisions and actions will require individual site investigations. The recent (Quaternary) geomorphology of the Esperance area where ASS materials may be found was a near-shore shallow marine and lacustrine/estuarine sedimentary environment. This was followed by a period of sea regression and deposition of aeolian (wind-blown) sands over these deposits. Thus, ASS materials have a high probability of occurrence in current low-lying areas, swamps and lakes. These landscapes cover about 8,140 ha of reserves, agricultural and rural-residential land around Esperance township. ASS materials may also be found under sand sheets and dunes that blanket lakes and swamps. In these situations, ASS materials are only likely to be intercepted in the swales (depressions) of dunes and under very shallow sand sheets, and so they are rated as having a low probability of occurrence. These landscapes cover about 2,170 ha of land, mostly on the southern (town) side of the lake system, extending east of Bandy Creek to near the wastewater treatment plant and tip. Much of this area is residential, light industrial, rural residential and unallocated Crown land. The soil-landscape map units that correspond to these geomorphological environments are the Gore 1, 2 and 3 subsystems and low-lying parts of the Tooregullup 5 subsystem. All other areas around Esperance, including headlands, larger dunes and sand sheets west of town, and all land north of the coastal plain that the lakes system occupies, is considered very low probability of occurrence. This study and existing protocols on identifying and managing ASS materials provides land planners and developers in Esperance with guidelines to manage potential issues relating to acid generation caused by dewatering or excavation

Avon Hotham catchment appraisal 2005

This report summarises current information on risks and impacts to agricultural production and natural resources within the Avon Hotham study area. It then identifies suitable options to manage such risks. The Avon Hotham study area is 1.9 million hectares and is made up of three sub catchments: West Avon, South Avon and Hotham, in south west Western Australia. Among the risks and impacts discussed are rainfall, surface drainage; major land degredation hazards are subsurface compaction and acidification

Pindan soils in the La Grange area, West Kimberley: land capability assessment for irrigated agriculture, 2nd edition

This report identifies areas of Pindan country along the Great Northern Highway, south of Broome from Roebuck to Mandora, which have high potential for irrigated agriculture. The area contains significant reserves of potable groundwater defined by the La Grange groundwater allocation area, which is based on the surficial Broome Sandstone aquifer. Over the past 30 years, several small- to medium-scale irrigation developments have been successfully established in the region. The water opportunities project aims to identify and quantify the land and water resources of the region to ensure any future expansion of irrigated agriculture is sustainable and will not have a detrimental impact on other land uses, environmentally sensitive areas, such as groundwater-dependent ecosystems, or areas of traditional cultural heritage. Pindan soils that are currently used for irrigated agriculture are predominantly deep, red, sandy earths. These soils are well drained to rapidly drained and do not develop a persistent perched watertable during the wet season. These soil characteristics potentially allow for year-round access and cropping. This land assessment identified over 50 000 hectares of Pindan soils that have a high to fair capability for irrigated agriculture where potable groundwater is within 20 metres. Groundwater is the main limiting resource and if allocated for irrigated agriculture, it should be used sustainably. Its usage should be restricted to land having a high capability for the proposed land use. The second edition of this report contains corrections in the soil chemical analysis tables (Appendix B), a revision of the Pindan soils classification to the Australian Soil Classification subgroup level, and corrections in the soil site classification table (Appendix C)

Phase-resolved spectral analysis of 4U 1901+03 during its outburst

The high mass X-ray binary 4U 1901+03 was reported to have the pulse profile evolving with the X-ray luminosity and energy during its outburst in February-July 2003: the pulse peak changed from double to single along with the decreasing luminosity. We have carried out a detailed analysis on the contemporary phase-resolved energy spectrum of 4U 1901+03 as observed by Rossi X-ray Timing Explorer (RXTE). We find that, both the continuum and the pulse spectra are phase dependent. The optical depth derived from the pulse spectrum is in general larger than that from the continuum. Fe Ka emission line is only detected in the spectrum of the continuum and is missing in the pulse spectrum. This suggests an origin of Fe emission from the accretion disk but not the surface of the neutron star.Comment: 18 pages, 8 figures, accepted by Ap

Eclipse Timings of the LMXB XTE J1710-281: Orbital Period Glitches

We present an X-ray eclipse timing analysis of the transient low mass X-ray binary XTE J1710-281. We report observations of 57 complete X-ray eclipses, made with the proportional counter array detectors aboard the RXTE satellite. Using the eclipse timing technique, we have derived a constant orbital period of 0.1367109674 (3) d, during the period from MJD 52132 upto MJD 54410; and 1{\sigma} limits of -1.6 $\times$ 10^ -12 d d-1 and 0.2 $\times$ 10^ -12 d d-1 , on the period derivative. This puts constraints on the minimum timescale of secular orbital period evolution of 2.34 $\times$ 10^8 yr for a period decay and 18.7 $\times$ 10^8 yr for a period increase. We also report detection of two instances of discontinuity in the mid-eclipse time, one before and one after the above MJD range. These results are interpreted as three distinct epochs of orbital period in XTE J1710-281. We have put lower limits of 1.4 ms and 0.9 ms on orbital period change at successive epochs.Comment: Accepted for publication in MNRAS Main Journal, 5 pages, 3 figure

Search for pulsations in the LMXB EXO 0748-676

We present here results from our search for X-ray pulsations of the neutron star in the low mass X-ray binary EXO 0748-676 at a frequency near a burst-oscillation frequency of 44.7 Hz. Using the observations made with the Proportional Counter Array on board the Rossi X-ray Timing Explorer we did not find any pulsations in the frequency band of 44.4 Hz to 45.0 Hz and obtained a 3\sigma upper limit of 0.47 % on the pulsed fraction for any possible underlying pulsation in this frequency band.Comment: Accepted for publication in "Research in Astronomy and Astrophysics", 7 pages, 3 figure