scholarly journals BARRON RIVER DELTA INVESTIGATION

1980 ◽  
Vol 1 (17) ◽  
pp. 54 ◽  
Author(s):  
D.A. Robinson ◽  
D.J. Cook ◽  
J.G. Barff
Keyword(s):  
Beach Sand ◽  
Annual Rainfall ◽  
Electric Power Station ◽  
River Flows ◽  
Farm Land ◽  
Main River ◽  
Eastern Australia ◽  
Sand And Gravel ◽  
The Tropics ◽  
Resort Towns

The Barron River flows to sea through a 50 km2 alluvial Delta on the narrow coastal plain near Cairns, Queensland in north eastern Australia. The Delta is in the tropics at 17 degrees south latitude. Most of the 2175 km2 catchment lies above 450 m above sea level. The coastal portion of the catchment has an average annual rainfall in excess of 2000 mm. River flows are highly variable with peak flood flows of over 4000 m3s"', and dry season flows of less than 15 m3s"'. The Delta is tidal with ocean tides having a range of 1.8 m at Spring Tides. There are three water storages on the catchment, one on the upper catchment having an ungated spillway and a capacity of 407 x 106 m3 for irrigation purposes and the other two just upstream of the Delta, are a small weir of 1.7 x 106 m3 capacity to regulate water supply to the Barron Gorge Hydro-electric Power Station, and Copperlode Falls Dam on Freshwater Creek, a 45 x 106 m3 ungated storage to provide water to Cairns City and the nearby Mulgrave Shire. The Delta consists of alluvial soils which support 3600 hectares of sugar cane farm land. The beaches in the Delta are being developed as resort towns and dormitory suburbs. Sand and gravel is reularly dredged from the lower reaches of the main river in the Delta at the rate of 50,000-80,000 m3 per year. Increasing scarcity of sand sources, and the concern that dredging and dam construction is threatening beach sand sources have raised conflicting pressures on the Authority which licences the extraction of sand and gravel from the river. This, coupled with regular flooding of the Delta and the cutting of major highways, and the continuing erosion of cane farm land has initiated a major data collection programme as a prerequisite to formulating solutions for the flooding and erosion problems.

An Empirical Study of the Relationship between Seasonal Precipitation and Thermodynamic Environment in Puerto Rico

2019 ◽  
Vol 34 (2) ◽  
pp. 277-288 ◽  
Author(s):  
Paul W. Miller ◽  
Thomas L. Mote ◽  
Craig A. Ramseyer
Keyword(s):  
Puerto Rico ◽  
Annual Rainfall ◽  
Seasonal Precipitation ◽  
Surface Precipitation ◽  
Precipitation Forecasting ◽  
Caribbean Islands ◽  
K Index ◽  
Groundwater Reserves ◽  
The Tropics ◽  
The Relationship

Abstract With limited groundwater reserves and few reservoirs, Caribbean islands such as Puerto Rico are largely dependent on regular rainfall to meet societal and ecological water needs. Thus, the ability to anticipate seasonal rainfall shortages, such as the 2015 drought, is particularly important, yet few reliable tools exist for this purpose. Consequently, interpolated surface precipitation observations from the Daymet archive are summarized on daily, annual, and seasonal time scales and compared to the host thermodynamic environment as characterized by the Gálvez–Davison index (GDI), a convective potential parameter designed specifically for the tropics. Complementing the Daymet precipitation totals, ≥1.1 million WSR-88D volume scans between 2002 and 2016 were analyzed for echo tops ≥ 10 000 ft (~3 km) to establish a radar-inferred precipitation activity database for Puerto Rico. The 15-yr record reveals that the GDI outperforms several midlatitude-centric thermodynamic indices, explaining roughly 25% of daily 3-km echo top (ET) activity during each of Puerto Rico’s primary seasons. In contrast, neither mean-layer CAPE, the K index, nor total totals explain more than 11% during any season. When aggregated to the seasonal level, the GDI strongly relates to 3-km ET (R2 = 0.65) and Daymet precipitation totals (R2 = 0.82) during the early rainfall season (ERS; April–July), with correlations weaker outside of this period. The 4-month ERS explains 51% (41%) of the variability to Puerto Rico’s annual rainfall during exceptionally wet (dry) years. These findings are valuable for climate downscaling studies predicting Puerto Rico’s hydroclimate in future atmospheric states, and they could potentially be adapted for operational seasonal precipitation forecasting.

Persistence and productivity of phalaris (Phalaris aquatica) germplasm in dry marginal rainfall environments of south-eastern Australia

2017 ◽  
Vol 68 (8) ◽  
pp. 781
Author(s):  
R. A. Culvenor ◽  
M. R. Norton ◽  
J. De Faveri
Keyword(s):  
Environmental Benefits ◽  
Annual Rainfall ◽  
Summer Drought ◽  
Environment Interaction ◽  
Phalaris Aquatica ◽  
Mixed Farming ◽  
Eastern Australia ◽  
Summer Dormancy ◽  
Average Annual Rainfall ◽  
Establishment Phase

Perennial grasses have production and environmental benefits in areas of southern Australia typified by the mixed farming zone of southern New South Wales (NSW). The perennial grass phalaris (Phalaris aquatica L.) is widely used in southern Australia; however, it would find more use in the mixed farming zone if its persistence in marginal rainfall areas (450–500 mm average annual rainfall) were improved. We evaluated a range of germplasm (n = 29) including wild accessions, lines bred from these, and existing cultivars for persistence and production at three sites in a summer-dry area of southern NSW with 430–460-mm average annual rainfall. Two sites were used over 4 years and the third site over 5 years. Summer dormancy, maturity time and seedling growth were also assessed. Analysis of genotype × environment interaction employing factor analytic models and accounting for spatial and temporal correlations indicated that changes in persistence occurred mainly over time rather than between sites. Ranking changes occurred in the dry establishment phase of the experiment and during a severe final summer drought, with few changes occurring in the intervening high-rainfall years. Lines that survived the establishment phase best had vigorous seedlings and earlier maturity, whereas those surviving the final summer best were earlier maturing and higher in summer dormancy with high winter-growth activity. Some later maturing lines within the higher summer dormancy group were less persistent. Some accessions from North Africa were the most persistent; also, populations bred from these and other more persistent accessions generally persisted and produced better than cultivars used presently. However, present cultivars were capable of high yield in the higher rainfall years. We suggest that persistence of higher summer dormancy cultivars over very dry years could be improved by selecting for earlier maturity time.

Accumulation of soil carbon under zero tillage cropping and perennial vegetation on the Liverpool Plains, eastern Australia

Soil Research ◽  
2009 ◽  
Vol 47 (3) ◽  
pp. 273 ◽  
Author(s):  
R. R. Young ◽  
B. Wilson ◽  
S. Harden ◽  
A. Bernardi
Keyword(s):  
Field Experiment ◽  
Soil Carbon ◽  
Cropping Systems ◽  
Annual Rainfall ◽  
Continuous Cropping ◽  
Zero Tillage ◽  
Accumulation Rates ◽  
Eastern Australia ◽  
Perennial Vegetation ◽  
Semi Arid

Australian agriculture contributes an estimated 16% of all national greenhouse gas emissions, and considerable attention is now focused on management approaches that reduce net emissions. One area of potential is the modification of cropping practices to increase soil carbon storage. Here, we report short–medium term changes in soil carbon under zero tillage cropping systems and perennial vegetation, both in a replicated field experiment and on nearby farmers’ paddocks, on carbon-depleted Black Vertosols in the upper Liverpool Plains catchment. Soil organic carbon stocks (CS) remained unchanged under both zero tillage long fallow wheat–sorghum rotations and zero tillage continuous winter cereal in a replicated field experiment from 1994 to 2000. There was some evidence of accumulation of CS under intensive (>1 crop/year) zero tillage response cropping. There was significant accumulation of CS (~0.35 Mg/ha.year) under 3 types of perennial pasture, despite removal of aerial biomass with each harvest. Significant accumulation was detected in the 0–0.1, 0.1–0.2, and 0.2–0.4 m depth increments under lucerne and the top 2 increments under mixed pastures of lucerne and phalaris and of C3 and C4 perennial grasses. Average annual rainfall for the period of observations was 772 mm, greater than the 40-year average of 680 mm. A comparison of major attributes of cropping systems and perennial pastures showed no association between aerial biomass production and accumulation rates of CS but a positive correlation between the residence times of established plants and accumulation rates of CS. CS also remained unchanged (1998/2000–07) under zero tillage cropping on nearby farms, irrespective of paddock history before 1998/2000 (zero tillage cropping, traditional cropping, or ~10 years of sown perennial pasture). These results are consistent with previous work in Queensland and central western New South Wales suggesting that the climate (warm, semi-arid temperate, semi-arid subtropical) of much of the inland cropping country in eastern Australia is not conducive to accumulation of soil carbon under continuous cropping, although they do suggest that CS may accumulate under several years of healthy perennial pastures in rotation with zero tillage cropping.

The Brigalow Catchment Study: III. Productivity changes on brigalow land cleared for long-term cropping and for grazing

Soil Research ◽  
2007 ◽  
Vol 45 (7) ◽  
pp. 512 ◽  
Author(s):  
B. J. Radford ◽  
C. M. Thornton ◽  
B. A. Cowie ◽  
M. L. Stephens
Keyword(s):  
Crop Production ◽  
Clay Soil ◽  
Soil Nutrient ◽  
Grain Protein Content ◽  
Annual Rainfall ◽  
Soil N ◽  
Stocking Rate ◽  
Beef Production ◽  
Eastern Australia ◽  
Productivity Decline

Productivity of grain crops and grazed pastures inevitably declines without soil nutrient replacement and may eventually make these enterprises unprofitable. We monitored these declines in north-eastern Australia during 23 years after clearing 2 of 3 adjacent brigalow catchments, in order to define the productivity levels of developed brigalow land over time. One catchment (11.7 ha) was used for grain production and another (12.7 ha) for beef production from a sown buffel grass pasture. There was no upward or downward trend in annual rainfall amounts throughout the study period. In the cropped catchment, grain yield from 14 winter crops without added nutrients declined significantly in 20 years from 2.9 to 1.1 t/ha.year on the upper-slope clay soil (92 kg/ha.year) and from 2.4 to 0.6 t/ha.year on the Sodosol (88 kg/ha.year). Crop production per year declined by 20% between 2 successive 10-year periods. Wheat grain protein content also declined with time, falling below the critical value for adequate soil N supply (11.5%) 12 years after clearing on the Sodosol and 16 years after clearing on the clay soil. Such declines in grain quantity and quality without applied fertiliser reduce profitability. The initial pasture dry matter on offer of 8 t/ha had halved 3 years after clearing, and a decline in cattle liveweight gain of 4 kg/ha.year was observed over an 8-year period with constant stocking of 0.59 head/ha. Due to fluctuating stocking rate levels of 0.3–0.7 head/ha over the trial period, liveweight productivity trends are attributed to the multiple effects of stocking rate changes and fertility decline. The amount of nitrogen exported from the cleared catchments was 36.1 kg/ha.year in grain but only 1.6 kg/ha.year in cattle (as liveweight gain). Total soil N at 0–0.3 m declined by 84 kg/ha.year under cropping but there was no significant decline under grazing. The soil nutrients removed during grain and beef production need to be replaced in order to avert productivity decline post-clearing.

Soil organic matter in rainfed cropping systems of the Australian cereal belt

Soil Research ◽  
2001 ◽  
Vol 39 (3) ◽  
pp. 435 ◽  
Author(s):  
R. C. Dalal ◽  
K. Y. Chan
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Management Practices ◽  
Performance Indicator ◽  
Annual Rainfall ◽  
Soil Productivity ◽  
Organic C ◽  
Soil C ◽  
Eastern Australia

The Australian cereal belt stretches as an arc from north-eastern Australia to south-western Australia (24˚S–40˚S and 125˚E–147˚E), with mean annual temperatures from 14˚C (temperate) to 26˚C (subtropical), and with annual rainfall ranging from 250 mm to 1500 mm. The predominant soil types of the cereal belt include Chromosols, Kandosols, Sodosols, and Vertosols, with significant areas of Ferrosols, Kurosols, Podosols, and Dermosols, covering approximately 20 Mha of arable cropping and 21 Mha of ley pastures. Cultivation and cropping has led to a substantial loss of soil organic matter (SOM) from the Australian cereal belt; the long-term SOM loss often exceeds 60% from the top 0–0.1 m depth after 50 years of cereal cropping. Loss of labile components of SOM such as sand-size or particulate SOM, microbial biomass, and mineralisable nitrogen has been even higher, thus resulting in greater loss in soil productivity than that assessed from the loss of total SOM alone. Since SOM is heterogeneous in nature, the significance and functions of its various components are ambiguous. It is essential that the relationship between levels of total SOM or its identif iable components and the most affected soil properties be established and then quantif ied before the concentrations or amounts of SOM and/or its components can be used as a performance indicator. There is also a need for experimentally verifiable soil organic C pools in modelling the dynamics and management of SOM. Furthermore, the interaction of environmental pollutants added to soil, soil microbial biodiversity, and SOM is poorly understood and therefore requires further study. Biophysically appropriate and cost-effective management practices for cereal cropping lands are required for restoring and maintaining organic matter for sustainable agriculture and restoration of degraded lands. The additional benefit of SOM restoration will be an increase in the long-term greenhouse C sink, which has the potentialto reduce greenhouse emissions by about 50 Mt CO2 equivalents/year over a 20-year period, although current improved agricultural practices can only sequester an estimated 23% of the potential soil C sink.

Crop stubbles are as important for sheep production as annual pastures in the Victorian Mallee

2006 ◽  
Vol 46 (8) ◽  
pp. 993 ◽  
Author(s):  
S. M. Robertson
Keyword(s):  
Plant Density ◽  
Cropping Systems ◽  
Management Strategies ◽  
Simulation Modelling ◽  
Annual Rainfall ◽  
Pasture Management ◽  
Pasture Production ◽  
Eastern Australia ◽  
Sheep Production ◽  
The Impact

The impact of different management strategies on production and profit can be evaluated with knowledge of how sheep production responds to changes in the available feed base and sheep or pasture management. This study aimed to quantify on-farm pasture and sheep production in mixed sheep and cropping systems in the Victorian Mallee of south-eastern Australia (325 ± 50 mm annual rainfall) as a prelude to computer simulation modelling. During 2001 (average rainfall) and 2002 (extreme drought) pasture production, the feed base and sheep production were monitored in 15 paddocks on 5 properties located across the region. Crop stubbles were the major source of feed for 6 months of the year, enabling ewes to maintain liveweight. There was more variation in pasture parameters between paddocks at the 1 location than between locations. The botanical composition, plant density, soil fertility and management were key variables associated with between-paddock variation in pasture production. Variation in pasture production between years was larger than within-year differences. In contrast, stocking rates were not much lower in the drought year of 2002 than in 2001. This study suggests there is potential for management to improve pasture production, and demonstrates the importance of feed sources other than annual pasture for sheep production in environments where the annual pasture growing season is short.

Rainfall erosivity and its estimation for Australia's tropics

Soil Research ◽  
1998 ◽  
Vol 36 (1) ◽  
pp. 143 ◽  
Author(s):  
B. Yu
Keyword(s):  
Model Performance ◽  
Daily Rainfall ◽  
Annual Rainfall ◽  
Rainfall Erosivity ◽  
Wet Season ◽  
R Factor ◽  
Different Seasons ◽  
Monthly Distribution ◽  
The Tropics ◽  
Parameter Values

Pluviograph data at 6-min intervals for 41 sites in the tropics of Australia were used to compute the rainfall and runoff factor (R-factor) for the Revised Universal Soil Loss Equation (RUSLE), and a daily rainfall erosivity model was validated for these tropical sites. Mean annual rainfall varies from about 300 mm at Jervois (015602) to about 4000 at Tully (032042). The corresponding R-factor ranges from 1080 to 33500 MJ·mm/(ha ·h·year). For these tropical sites, both rainfall and rainfall erosivity are highly seasonal with a single peak in February mostly. Summer months (November–April) typically contribute about 80% of annual rainfall and about 90% of the R-factor. The daily erosivity model performed better for the tropical sites with a marked wet season in summer in comparison to model performance in temperate regions of Australia where peak rainfall and peak rainfall erosivity may occur in different seasons. A set of regional parameters depending on seasonal rainfall was developed so that the R-factor and its seasonal distribution can be estimated for sites without pluviograph data. The prediction error using the regional parameter values is about 20% for the R-factor and 1% for its monthly distribution for these tropical sites.

Ecological studies on reproduction and establishment of the woody weed, groundsel bush (Baccharis halimifolia L.: Asteraceae)

1975 ◽  
Vol 26 (5) ◽  
pp. 855 ◽  
Author(s):  
WE Westman ◽  
FD Panetta ◽  
TD Stanely
Keyword(s):  
Integrated Control ◽  
High Light Intensity ◽  
Annual Rainfall ◽  
Cool Temperature ◽  
Vegetative Cover ◽  
Baccharis Halimifolia ◽  
Tall Plant ◽  
Coastal Species ◽  
Eastern Australia ◽  
Total Seed

Groundsel bush (Baccharis halimifolia) is spreading southward along the coastal range of eastern Australia where the annual rainfall exceeds 90 cm. This advance conforms with its cool temperature optimum for germination (15-20�C) and its superior germination when given a cold pretreatment (5�C for 1 week). The species has a facultative light requirement for germination, which suggests that the maintenance of a very dense vegetative cover in the herb layer could discourage establishment of the weed. Once established, however, B. halimifolia can produce viable seed in very dense shade (3 % of open light conditions), even though total seed production per plant is reduced. Prolific seeding occurs with high light intensity. Thus a tall plant (2 m) may release c. 1.5 million seeds. Seedlings possess an unusual ability to maintain growth under low nitrogen conditions during their first 13 weeks, and to survive even when the supply of all nutrients is poor. Seedlings showed no growth response when the strength of a standard nutrient solution was doubled. The fact that growth is not inhibited under enriched nutrient conditions, however, may account for the superior competitive performance of B, halimifolia on fertilized sites containing native coastal species adapted to low soil fertility. Implications with respect to integrated control of the weed are briefly discussed.

Patterns of Distribution of Acacia in Australia

1988 ◽  
Vol 36 (4) ◽  
pp. 385 ◽  
Author(s):  
BR Maslin ◽  
L Pedley
Keyword(s):  
Species Richness ◽  
Western Australia ◽  
Arid Zone ◽  
Patterns Of Distribution ◽  
The North ◽  
Geographic Patterns ◽  
South West ◽  
Eastern Australia ◽  
Semiarid Areas ◽  
The Tropics

Patterns of distribution are described for the three subgenera and nine sections that make up the Australian Acacia flora. Subgenus Phyllodineae (833 species) is widespread and contains 99% of the species; subgenus Acacia (six species) and subgenus Aculeiferum (one species) are poorly represented and virtually confined to the north of the continent. The geographic patterns of species-richness are strongly influenced by sections Phyllodineae (352 species), Juliflorae (219 species) and Plurinerves (178 species). Section Phyllodineae has centres of richness south of the Tropic of Capricorn in temperate and adjacent semiarid areas of eastern, south-eastern and south-western Australia. The section is poorly represented in the tropics. The closely related sections Juliflorae and Plurinerves predominate in the north of the continent, semiarid areas of the south-west, many rocky tablelands of the Arid Zone and along the Great Dividing Range and adjacent inland riverine lowland areas in eastern Australia. The remaining four sections contribute little to the overall patterns of species-richness. The principal speciespoor areas are sandy and fluvial lowland regions of the Arid Zone. In eastern Australia, sections Botrycephalae, Juliflorae, Phyllodineae and Plurinerves show discontinuous patterns of species-richness along the Great Dividing Range. All sections have species whose ranges terminate in the area of the McPherson-Macleay Overlap region.

Population Studies on Acacia melanoxylon R. Br. I. Variation in Seed and Vegetative Characteristics

1978 ◽  
Vol 26 (3) ◽  
pp. 365 ◽  
Author(s):  
TP Farrell ◽  
DH Ashton
Keyword(s):  
Environmental Parameters ◽  
Morphological Characters ◽  
Annual Rainfall ◽  
Clinal Variation ◽  
Acacia Melanoxylon ◽  
Open Forest ◽  
Popu Lations ◽  
Eastern Australia ◽  
Closed Forest ◽  
Shape And Size

Considerable variation in phyllode shape and size was found between populations of Acacia melanoxylon sampled over the wide geographical range (27° of latitude) of this species in tropical and temperate eastern Australia. Communities sampled range from closed-forest to open-forest and grassy woodland. Some evidence of relationships between morphological characters of the phyllodes and environ- mental conditions of the collecting site was found, although such relationships are complex and not easily understood. The most important factors determining phyllode shape and size were the distance of the collecting site from the coast, and the seasonal distribution of the annual rainfall. Phyllodes tended to be smaller and more symmetric in the drier inland areas. Differences were found between seed characteristics of selected populations, although there was no evidence of correlation of these with selected environmental parameters. Seedlings of 17 popu- lations of A. melanoxylon grown under uniform glasshouse conditions showed some differences in leaf morphology. The age at which conversion to phyllodes begins is correlated with the mean annual rainfall at the site of origin of the seeds. The occurrence of this species in such a wide variety of habitats in eastern Australia is probably due to its clinal variation.

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