Regional planning for the siting of local evaporation basins for the disposal of saline irrigation drainage: development and testing of a GIS-based suitability approach

In order to prevent salinisation of the streams of the Riverine Plain of the Murray-Darling Basin in southern Australia, evaporation basins are used to dispose of saline irrigation drainage water. Local on-farm (individual landholder) and community (shared between multiple landholders) basins are increasingly being used to prevent export of salt outside irrigation districts. There are questions regarding the availability of land suitable for these basins and their impact on the surrounding environment. We describe the use of currently available spatial data to assist in regional planning for the environmentally safe use of these basins. A GIS-based approach was developed using suitability criteria expected to minimise the risk of off-site effects of basin leakage. The criteria were proximity to surface water features, urban areas and infrastructure, water table depth and salinity, and soil hydraulic conductivity. The approach was applied to all of the major irrigation districts at 1:250,000, the scale at which data are available over the entire Riverine Plain. Confidence in well-defined parameters such as proximity to infrastructure, urban areas and surface water features was higher than for those involving interpolated point data such as water table depth, salinity, and hydraulic conductivity. Most critically, hydraulic conductivity, the most important factor for basin leakage, was found to be unreliable at this scale. Use of higher resolution data (up to 1:100,000) available for two of the irrigation districts improved confidence in both water table depth and salinity but not in hydraulic conductivity. Despite these limitations, it was found that: (i) on-farm basins can only be used on an opportunistic basis in the eastern irrigation districts, but can be widely used in the western districts; (ii) community basins can be used anywhere there is suitable land; and (iii) the results raise serious questions as to whether there is enough suitable land in the eastern districts to dispose of all of the drainage water that is produced.     

Exploring spatial patterns of particulate sulfur and OMH from the Project MOHAVE summer intensive regional network using analyses of variance techniques and meteorological parameters as sort determinants

Project MOHAVE (Measurements of Haze and Visual Effects) encompassed a 1-yr field study in the southwestern United States from September 1991 through August 1992. The congressionally mandated study was a joint partnership between the U.S. Environmental Protection Agency, Southern California Edison, and the National Park Service. A major objective of this study was to quantify the potential haze impacts on the nearby Grand Canyon National Park from the 1580 MW coal-fired MOHAVE Power Project (MPP). Any regional impacts from MPP were from secondary fine sulfate. In this paper, we explore the temporal and spatial patterns of particulate sulfur (Sp) and "organic mass by hydrogen" (OMH) during the summer intensive, conducted from mid-July through the end of August 1992. Using an innovative hierarchical pattern recognition classification scheme, we developed 6 groups of Sp and 8 groups of OMH temporally similar behaving patterns in the sampling region. From a regional understanding of synoptic meteorology, these Sp patterns were explainable. We observed two regional gradients. One gradient was a west-to-east decreasing gradient, most likely the result of major sources from urban southern California, including the San Joaquin Valley. The other decreasing gradient was from south-to-north, perhaps the result of emissions emanating from the large urban centers in northern Mexico. The patterns for OMH were not as regionally homogeneous as the patterns for Sp. A west-to-east decreasing gradient was observed for OMH, along with reduced values in the lower Colorado River Valley and some higher values in central and eastern Arizona. The west-to-east decreasing gradient suggests the presence of the Los Angeles urban plume, while the higher values in central and eastern Arizona may be due to biogenic emissions and increased seasonal fires.     

Gender and drought: experiences of Australian women in the drought of the 1990s

A unique collaborative, sociological study undertaken during 1995-7, explored the social construction of drought as a disaster, looking at farm families in two Australian states: Queensland (beef producers) and New South Wales (sheep/wheat producers). A decision was made to interview the women and men separately to test our hypothesis that there would be gender issues in any analysis of a disaster, but particularly one which has had so much long-term impact on individuals, families and communities, such as drought. Interviews were conducted with over 100 individuals male and female. We conclude that drought as a disaster is a gendered experience. The paper draws on the narratives of some women involved in the study to identify 'themes of difference' which confirm the necessity to maintain gender as a variable in all studies of the social impacts of disaster.     

Evaluating three trace metal contaminated sites: a field and laboratory investigation

Selecting guidelines to evaluate elevated metals in urban brownfields is hindered by the lack of information for these sites on ecosystem structure and function. A study was performed to compare three trace metal-contaminated sites in the metropolitan Montreal area. The goal was to obtain an idea of the organisms that may be present on urban brownfields and to measure if elevated metals alter the presence and activity of the indigenous biota. Field and laboratory studies were conducted using simple methodologies to determine the extent to which microbial activity affected by trace metal content, to assess diversity of plant and soil invertebrate communities and to measure phytoaccumulation of trace metals. It was found that microbial activity, as measured by substrate-induced respiration (SIR) and nitrification, was not affected by the levels of soil Cd, Cu, Ni, Pb and Zn recorded on the sites. Seven of the 12 invertebrate groups collected were sampled on soils with similar Cd, Cu, Ni, Pb and Zn concentrations. Diversity of plant species increased as a function of the length of time the sites had been inactive. Levels of metals in plant tissue were influenced by soil characteristics and not by total soil Cd, Cu, Ni, Pb and Zn.     

Changing patterns of radionuclide distribution in Irish Sea subtidal sediments

This paper presents new data on the distribution of long-lived radionuclides in Irish Sea subtidal sediments, contaminated as a result of the BNFL Sellafield discharges. The results from different sampling campaigns in 1999 have been combined to assess the extent of radionuclide mobility relative to earlier surveys, in both the eastern and western Irish Sea areas, and to investigate changes in radionuclide distribution over time. The results appear to confirm the trend of continuing re-distribution and transfer of contamination away from the English coast. West of the Isle of Man, radionuclide concentrations and inventories have remained more or less constant. The inventory of radionuclides in sandy sediments in the eastern Irish Sea is still under-represented by current sampling, but could be improved by deeper and more extensive vibrocoring.