Добірка наукової літератури з теми "Salinity Victoria Goulburn Region"

The results from a survey of 269 test wells in an area with shallow watertables were used to derive a relationship between soil salinity to 60 cm depth (Y) and watertable depth (X1) and watertable salinity (X2). The survey area (730 km2) was in the Goulburn Valley of Victoria and included irrigated and non-irrigated pastures. The relationship was described by the multiple Regression ln Y = a + b ln X1 + c ln X2 The equations were: Perennial pastures ln Y = 7.3859 - 0.607l.ln X1 + 0.2925.ln X2 (r = 0.50, P= 0.0000002, n = 109) Annual pastures ln Y = 7.2690 - 0.7252.ln X1 + 0.3743.ln X2 (r=0.54, P=0.00349, n=36) Dryland pastures ln Y = 10.8417 - 1.3779.ln X1 + 0.4024.ln X2 (r= 0.73, P= 0.0003, n = 24) It was concluded that both depth and salinity of the watertable determine its hazard to soil salinity; watertable depth alone can be misleading. The effect of watertable salinity was greater than that of watertable depth. Similar models could be developed for other regions if data for the regions were available.

In response to a local survey that revealed that many farmers in the Goulburn Valley region of Victoria did not adhere to recommendations for safely applying saline irrigation water to perennial pasture, an experiment was conducted at Tatura. Six irrigation water quality treatments, which differed in the timing of the application of saline water, were applied to perennial pasture plots over 4 irrigation seasons. Measurements made included soil EC1:5, soil SAR1:5, soil ESP, pasture dry matter production and composition, dry matter digestibility, tissue ion concentrations and mineral ash content. After 4 seasons, in which the winter rainfall for each season was significantly lower than the long-term average, soil sodicity and salinity levels appeared to reach steady values. Plots irrigated with non-saline water (0.1 dS/m, treatment 1) performed the best in terms of lower soil salinity and sodicity levels and higher dry matter production and pasture quality levels. However, for most of these measurements and for most seasons, there were no significant differences between the control plots and those irrigated with water at 1.2 dS/m (treatment 2). Soil EC1:5 and SAR1:5 levels were highest, and dry matter production and dry matter digestibility levels the lowest (particularly for the clover component), in plots irrigated with water at 2.4 dS/m throughout the season (treatment 6). There were no significant differences in soil characteristics or biomass production between the remaining 3 treatments (treatments 3, 4 and 5) or between treatment 2. These treatments had the same amount of salt applied throughout the season but differed in the pattern of salt application — whether it occurred at the beginning or end of the season, or was alternated with fresh water throughout the season. This study confirmed that in the long term, there is a reduction in the yield of perennial pastures when saline irrigation water at levels greater than 0.8–1.2 dS/m is used on the red-brown earths of the Shepparton Irrigation Region. However, the soil and pasture were more sensitive to the total amount of salt applied rather than to the pattern of salt application throughout the season. It was concluded that farmers should monitor the salinity levels of their irrigation water to avoid a build up of Na+ and Cl– in the soil profile and consequent long-term reductions in herbage production and quality.

This paper illustrates the hydrological limitations and underlying assumptions of 4 catchment modelling approaches representing different generic classes of predictive models. These models are commonly used to estimate the impacts of land use and management change on stream flow and salinity regimes within a target region. Three approaches are based on a simple conceptual framework that assumes a single layer groundwater aquifer and requires minimal information and calibration (Zhang-BC2C, CAT1D-BC2C and LUCICAT), whereas the fourth approach (CAT3D) adopts a fully distributed highly parameterised catchment model capable of simulating complex multi-layered groundwater aquifer systems. All models were applied to the Gardiner subcatchment within the Goulburn–Broken region of Victoria, identified as a National Action Plan for Salinity priority subcatchment. Current condition simulation results were compared with observed stream flow and groundwater hydrograph data. Results show that the simple frameworks predicted whole-of-catchment mean annual salt and water yield with minimum parameterisation. The fully distributed framework produced similar catchment-scale responses to the simple approaches, but required more intensive input data and solution times. However, the fully distributed framework provides finer temporal and spatial scale information within the catchment. The more detailed models (such as CAT3D) also have the predictive capacity to assess the within-catchment dynamics at a range of scales and account for landscape position and complex surface/groundwater interactions. This paper concludes that the simple frameworks are useful for judging the whole-of-catchment impacts of broad-scale land use change on catchment water yields and salinity and therefore provide valuable tools for community engagement. However, the within-catchment dynamics are not well represented and particular care must be taken when applying such models in those catchments where the interaction between groundwater and surface features result in saturated areas that are disconnected from streams. Adoption of a distributed groundwater modelling environment similar to that of CAT3D provides higher spatial resolution relative to the lumped broad scale groundwater glow system (GFS) based parameterisation adopted by the BC2C rapid assessment approaches. The developers of the BC2C model acknowledge that such models are currently limited to upland local and intermediate groundwater flow systems. Given that the majority of land salinisation is located in regions dominated by intermediate and regional groundwater systems, this tool is not well suited to adequately model regional processes. In contrast, the CAT3D distributed groundwater models are likely to be applicable across a range of scales and provide the capacity to assess the trade offs between salinity recharge and discharge intervention strategies. We conclude that more complex models (e.g. CAT3D) are needed to identify at the land management scale (paddock/farm) cost effective land use and land management changes within the catchment to improve catchment health.

In 1985, groundwater pumping from shallow aquifers, with off-farm disposal, began near Girgarre in the Goulburn Valley, Victoria, to provide salinity control to about 1000 ha of farming land. Two groundwater pumps (TI02 and T103) ran continuously for the first 5 years of the project before reverting to intermittent pumping. The operation of a third pump (T103) was based on the capacity for disposal into an evaporation basin. Following 3 years of groundwater pumping, significant reductions in root-zone (0-0.6 m) soil salinity levels were recorded in both annual and perennial pasture paddocks within 350 m of a pump. Yields of perennial pasture on all monitored paddocks showed a significant increase after commencement of the project. In a paddock 300 m from a groundwater pump, average dry matter production increased from 6.3 to 17.2 t/ha. year within 4 years of pumping. Reclamation was reduced by more than a year on paddocks not subjected to irrigation, or those located >800 m from a groundwater pump. Once reclamation was achieved from continuous pumping, the introduction of intermittent pumping continued to maintain optimum soil salinity and pasture production levels on the irrigated paddocks. However, on a dryland paddock and those located >800 m from a pump, increasing fluctuations in soil salinity and soil sodicity levels were measured under this management regime.

The introduction of watertable control by groundwater pumping on a salt-affected dairy farm in the Goulburn Valley resulted in large increases in butter fat production. Since intensive pumping started, in 1981, watertable levels showed an overall downward trend but were still subject to major fluctuations caused by irrigation and rainfall. During this period butterfat production increased from about 300 to 390 kg/ha (of productive land) and yearly pasture production rose from about 560 to 650 t/ha DM. These productivity increases are attributed to both a reduction in average soil salinity in the top 60 cm of the profile from 2400 to 1200 mg total dissolved salts per kg dry soil and an increase in irrigation water use from less than 10 M litre/ha before to nearly 12 M litre/ha after pumping started.

The Shepparton Irrigation Region Land and Water Salinity Management Plan promotes groundwater pumping and re-use for irrigation where groundwater quality and availability allow dilution with channel water (‘conjunctive water use’) to levels that produce minimal production losses from annual and perennial pastures used widely for dairying. In addition, municipal and industrial waste waters are used on a smaller scale for irrigating pastures (and crops). An upper level of irrigation water salinity (expressed as an electrical conductivity of 0.8 dS/m) is currently recommended in the plan. This recommendation is based on empirical data from experiments on unstocked, perennial pasture collected over 2 decades on red-brown earths in the region. While the strategy has, so far, achieved acceptable control of soil salinity levels, while generally maintaining pasture yields, a concern that ‘conjunctive water use’ may not be sustainable in the long term arises from the sodicity of the groundwater and waste waters. The continual addition of sodium to clay soils, initially low in both sodium and electrolytes (upper 0.5 m depth), risks the soils becoming sodified, with attendant soil physical problems should salts be leached to below threshold electrolyte concentrations, as in winter for example. We show that clay soils supporting pastures in the Shepparton Irrigation Region sodify with time under ‘conjunctive water use’. We review evidence for adverse effects of such sodification on soil physical properties affecting plant productivity and hydrologic processes important in the long-term sustainability of the strategy. On-farm management implications of the strategy are discussed and important issues for research are identified.

ABSTRACT The Drygalski Ice Tongue presents an ~80 km long floating obstacle to alongshore flows in the Victoria Land coastal ocean region of the Western Ross Sea. Here we use oceanographic data from near to the tongue to explore the interplay between the floating glacier and the local currents and stratification. A vessel-based circuit of the glacier, recording ocean temperature and salinity profiles, reveals the southwest corner to be the coldest and most complex in terms of vertical structure. The southwest corner structure beneath the surface warm, salty layer sustains a block of very cold water extending to 200 m depth. In this same location there was a distinct layer at 370 m not seen anywhere else of water at ~−1.93°C. The new observations broadly, but not directly, support the presence of a coherent Victoria Land Coastal Current. The data suggest the northward moving coastal current turns against the Coriolis force and works its way anticlockwise around the glacier, but with leakage beneath the glacier through the highly ‘rippled’ underside, resulting in a spatially heterogeneous supply to the Terra Nova Bay Polynya region – an important location for the formation of high-salinity shelf water.

Swamp paperbark, Melaleuca ericifolia Sm., is a small, clonal tree that occupies fresh- and brackish-water wetlands across south-eastern Australia. Seeds collected from Dowd Morass, a secondary-salinised Ramsar-listed wetland of the Gippsland Lakes region in eastern Victoria, showed very low viability (< 6%), with less than 50% of the seeds germinating even under ideal laboratory conditions. Greatest germination occurred with surface-sown seeds, germinated in darkness at a mean temperature of 20°C and salinity < 2 g L–1. At 20°C, maximum germination occurred at a salinity of 1 g L–1; germination fell rapidly at a near constant rate with increasing salinity. Lower temperatures, while moderating the inhibitory effects of salinity, markedly reduced germination; higher temperatures increased the inhibitory effects of salinity and light and reduced overall germination rates. Seeds subjected to brief inundation with saline water germinated rapidly if flushed by, and subsequently grown under, freshwater conditions. Specific timing of management interventions, particularly manipulations of water regime to control salinity regimes, are required if germination of M. ericifolia on the landscape scale is to be successful. Even so, the low overall viability of the seeds would present difficulties to large-scale, seed-based rehabilitation efforts.

Innovative solutions are required to meet the conflicting criteria of service level, community need, community desire, cost and risk to the supply authority in the delivery of water quality improvements to small regional communities. Grampians Region Water Authority services 74 towns in North-Western Victoria, an area of generally low rainfall, sparse settlement and few natural waterways. Town populations range from 10 to 13,000, with 56 towns having less than 500 people. A Water Quality Improvement Plan was recently developed by Grampians Water to address these natural difficulties. The plan examined a broad range of alternatives beyond the single-pipe reticulated supply system, including dual-pipe reticulation, rainwater sources and household water treatment systems for achieving target quality levels. The key findings were:• regional treatment plants are not economical if towns are more than 25 km apart• salinity is a major influence on strategy• for low salinity supplies, conventional treatment is most economical• for marginal salinity supplies, a two stage process involving conventional treatment and desalination is appropriate• desalination provides a total solution for high salinity groundwater supplies• drinking quality can only be economically achieved in very small towns by using household treatment of rainwater in a dual supply system. The resultant strategies and implementation issues outlined reveal some significant variations to the conventional approach.