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1
Hogg, ID, e RH Norris. "Effects of runoff from land clearing and urban development on the distribution and abundance of macroinvertebrates in pool areas of a river". Marine and Freshwater Research 42, n. 5 (1991): 507. http://dx.doi.org/10.1071/mf9910507.
Testo completoAbstract (sommario):
We examined the effects of runoff from urban land clearing and development on the macroinvertebrate pool fauna of the Murrumbidgee River, Australia, over 1 year. Tuggeranong Creek, which flows through the urban development, often recorded higher instantaneous (storm) discharges than did the Murrumbidgee River. Monitoring of suspended solids during one storm event revealed high concentrations of suspended solids (max. 560 mg L-1) entering the Murrumbidgee River for an 8 h period. Such concentrations were not detected by regular two-monthly sampling, although concentrations were generally higher downstream of Tuggeranong Creek. Analysis of substratum particle size revealed a higher proportion of fine inorganic material (<250 pm) at stations downstream of Tuggeranong Creek, suggesting a settling of fine material discharged during storm events. Number of taxa and macroinvertebrate density were lower at downstream stations. We conclude that the deposition of fine inorganic sediment following storm events, and the resulting change in the composition of the substratum, was the major cause of low invertebrate numbers in pools downstream of the cleared catchment.
2
Kingsford, R. T., e R. F. Thomas. "Use of satellite image analysis to track wetland loss on the Murrumbidgee River floodplain in arid Australia, 1975-1998". Water Science and Technology 45, n. 11 (1 giugno 2002): 45–53. http://dx.doi.org/10.2166/wst.2002.0378.
Testo completoAbstract (sommario):
Demonstrating the extent of wetland loss and its causes are essential for policy makers and managers. We used Landsat satellite imagery to show major wetland loss in the Lower Murrumbidgee floodplain on the Murrumbidgee River in arid Australia. Stratification of the floodplain according to hydrology, use of imagery from the same time of year and the separation of developed areas, using ancillary information were essential. There was considerable loss of floodplain area over a 23 year period (1975-1998), mainly in the Nimmie-Caira stratum (59% loss), as wetland areas were replaced by irrigation bays. There was also a significant increase in fragmentation. For floodplain areas distant from the river, flooding patterns were more difficult to identify because of infrequent flooding and primary reliance on rainfall. Landsat imagery provided a powerful tool for demonstrating long-term changes in wetland area, even in highly variable environments. Such information can demonstrate the ecological costs of water resource development on floodplains, forming a basis for policy and management of rivers.
3
Vink, S., M. Bormans, P. W. Ford e N. J. Grigg. "Quantifying ecosystem metabolism in the middle reaches of Murrumbidgee River during irrigation flow releases". Marine and Freshwater Research 56, n. 2 (2005): 227. http://dx.doi.org/10.1071/mf04187.
Testo completoAbstract (sommario):
The relative importance of floodplain carbon inputs and in-stream metabolic processes have not been well quantified in major Australian rivers. We quantified seasonal phytoplankton primary production and net ecosystem production during irrigation flow regimes at four sites each located ~100 km apart in the middle Murrumbidgee River. During flow periods dominated by storage release, ecosystem gross primary productivity, system respiration and phytoplankton chlorophyll concentrations all increased downstream so that overall net ecosystem metabolism was strongly net heterotrophic upstream and closer to balanced downstream. Phytoplankton production dominated ecosystem production throughout the entire reach and was likely to have been phosphorus limited throughout the study. Additionally, phytoplankton biomass was limited by short residence times at the upstream sites and nitrogen limited downstream in summer, despite an increase in turbidity. Both production and respiration rates were generally lower in winter, as expected, owing to lower temperatures.
4
Lindley, I. D. "Acanthodian fish remains from the Lower Devonian Cavan Bluff Limestone (Murrumbidgee Group), Taemas district, New South Wales". Alcheringa: An Australasian Journal of Palaeontology 24, n. 1 (gennaio 2000): 11–35. http://dx.doi.org/10.1080/03115510008619520.
Testo completo
5
Timms, W., e R. I. Acworth. "Origin, lithology and weathering characteristics of Upper Tertiary ‐ Quaternary clay aquitard units on the Lower Murrumbidgee alluvial fan". Australian Journal of Earth Sciences 49, n. 3 (giugno 2002): 525–37. http://dx.doi.org/10.1046/j.1440-0952.2002.00936.x.
Testo completo
6
Wen, Li, Kerrylee Rogers, Joanne Ling e Neil Saintilan. "The impacts of river regulation and water diversion on the hydrological drought characteristics in the Lower Murrumbidgee River, Australia". Journal of Hydrology 405, n. 3-4 (agosto 2011): 382–91. http://dx.doi.org/10.1016/j.jhydrol.2011.05.037.
Testo completo
7
Llewellyn, L. C. "Movements of Golden PerchMacquaria ambigua(Richardson) in the mid Murray and lower Murrumbidgee Rivers (New South Wales) with notes on other species". Australian Zoologist 37, n. 2 (gennaio 2014): 139–56. http://dx.doi.org/10.7882/az.2013.014.
Testo completo
8
Wen, Li, Kerrylee Rogers, Neil Saintilan e Joanne Ling. "The influences of climate and hydrology on population dynamics of waterbirds in the lower Murrumbidgee River floodplains in Southeast Australia: Implications for environmental water management". Ecological Modelling 222, n. 1 (gennaio 2011): 154–63. http://dx.doi.org/10.1016/j.ecolmodel.2010.09.016.
Testo completo
9
James, DG. "Energy Reserves, Reproductive Status and Population Biology of Overwintering Biprorulus-Bibax (Hemiptera, Pentatomidae) in Southern New-South-Wales Citrus Groves". Australian Journal of Zoology 38, n. 4 (1990): 415. http://dx.doi.org/10.1071/zo9900415.
Testo completoAbstract (sommario):
Information is presented on energy reserves, reproductive status and population biology of over- wintering Biprorulus bibax (Breddin) in southern New South Wales citrus groves. Large numbers of adult bugs overwintered in clusters on orange trees adjacent to a lemon grove at Cudgel in the Murrumbidgee Irrigation Area (M.I.A.). Clusters of up to 50 tightly packed bugs were found on single trees, and dispersed into the adjacent lemons in early October. Clustering was observed on all citrus except lemon. Overwintering bugs were non-reproductive. Individuals obtained from overwintering clusters at Dareton in Sunraysia were larger, heavier and contained greater lipid reserves than bugs which overwintered alone. These differences did not occur in cluster and non-cluster bugs from the M.I.A. Bugs overwintering on lemons in the M.I.A. weighed less and contained lower reserves of lipid than did individuals which overwintered on orange, mandarin and grapefruit. Lipid reserves of B. bibax were not greatly depleted during overwintering. Overwintering in clusters on citrus hosts other than lemon appears to be an important and successful behavioural strategy for B. bibax in commercial citrus groves in southern New South Wales.
10
Briggs, Sue V., Nicola M. Taws, Julian A. Seddon e Bindi Vanzella. "Condition of fenced and unfenced remnant vegetation in inland catchments in south-eastern Australia". Australian Journal of Botany 56, n. 7 (2008): 590. http://dx.doi.org/10.1071/bt08046.
Testo completoAbstract (sommario):
Considerable areas of remnant native vegetation have been fenced in the last decade to manage grazing by domestic stock. This study investigated vegetation condition in comparative fenced and unfenced remnant vegetation in the mid–upper Murrumbidgee and Lachlan catchments in south-eastern Australia. Native species richness, native groundcover and overstorey regeneration were higher at fenced than at unfenced sites. Area of bare ground was lower at fenced sites. Exotic groundcover did not differ between fenced and unfenced sites. Native species richness was higher at sites fenced for longer and with no stock grazing; neither native nor exotic groundcover at fenced sites was related to time since fencing or stock grazing pressure. Some tree species regenerated at both fenced and unfenced sites (Blakely’s red gum, Eucalyptus blakelyi; tumbledown gum, E. dealbata, long-leaved box, E. goniocalyx; red stringbark, E. macrorhyncha), some regenerated at few fenced and few unfenced sites (white box, E. albens; yellow box, E. melliodora) and some regenerated at fenced sites but not at unfenced sites (grey box, E. microcarpa; mugga ironbark, E. sideroxylon; white cypress pine, Callitris glaucophylla). Although less robust than pre- and postfencing monitoring, the comparisons reported here provide a logistically feasible and relatively inexpensive assessment of effects of the sizeable public investment in fencing on vegetation condition.
11
Ryder, Darren S., Robyn J. Watts, Errol Nye e Adrienne Burns. "Can flow velocity regulate epixylic biofilm structure in a regulated floodplain river?" Marine and Freshwater Research 57, n. 1 (2006): 29. http://dx.doi.org/10.1071/mf05099.
Testo completoAbstract (sommario):
Scour is one of the most important regulators of biofilm structure and function, especially in floodplain rivers where low gradients and flood frequencies limit potential for scouring. In this study, we experimentally examined the effects of flow velocity on the biomass and taxonomic composition of epixylic biofilms from floodplain reaches of the Murrumbidgee River, south-eastern Australia. Six blocks from each combination of colonisation period (30 or 70 days) and condition (wet or dried), were individually exposed to no velocity (control), or velocities of 0.3 m s−1 (low), 0.55 m s−1 (intermediate), or 1 m s−1 (high) in a laboratory flume. Biofilms exposed to all the experimental velocities had significantly lower dry mass (F3,94; P < 0.001), ash-free dry mass (F3,94; P < 0.001) and chlorophyll a (F3,94; P < 0.001) than the control. Losses of ash-free dry mass (F1,94; P < 0.05) and chlorophyll a (F1,94; P < 0.001) were significantly higher from wet biofilms exposed to each velocity than from dried biofilms. All velocities resulted in a substantial reduction in taxonomic richness among all treatments, with filamentous chlorophytes completely removed by velocities of 0.55 m s−1. These results indicate the potential to delineate thresholds for the response of biofilm biomass and algal taxa to flow velocity in floodplain rivers based on knowledge of antecedent conditions regulating biofilm development. This information significantly improves our understanding of the potential for ecological change using environmental flow releases in low-gradient floodplain rivers.
12
Woolfrey, A. R., e P. G. Ladd. "Habitat preference and reproductive traits of a major Australian riparian tree species (Casuarina cunninghamiana)". Australian Journal of Botany 49, n. 6 (2001): 705. http://dx.doi.org/10.1071/bt01009.
Testo completoAbstract (sommario):
The population structure and reproductive biology of the river oak (Casuarina cunninghamiana) were studied along the Murrumbidgee River on the Southern Tablelands of eastern Australia. The species has cone-like infructescences but is not serotinous, with samaras released when they are mature. Samaras were mostly distributed by wind close to female trees but were also carried by water. The first year of study (1985) appeared to be a mast year for seed production with much lower seed fall in the following year. Seedling establishment was spatially very variable, mostly under female canopies and appeared earlier on soil within the river channel than on the bank. Turnover was high and seedlings in the river channel generally died after being inundated. Most trees were within 3 m of the mean river level. However, the total distribution of adults was within the envelope of maximum floods in the area but establishment was not dependent on floods. The population structure was the result of yearly recruitment, although episodic events (floods, drought) may enhance or decrease establishment. Pot-trial results paralleled the field situation with substrate and water-table level not affecting germination of seed but strongly influencing seedling growth. Plants grew best on cobble substrates under a low water-table regime and poorly on cobbles with high water and sandy substrate under all water-table levels. Cobble banks seemed the best substrate for growth within the river channel and establishment may be prolific. Less-abundant seedling establishment occurred upslope but controls over this were not investigated.
13
Richter, H., A. W. Western e F. H. S. Chiew. "The Effect of Soil and Vegetation Parameters in the ECMWF Land Surface Scheme". Journal of Hydrometeorology 5, n. 6 (1 dicembre 2004): 1131–46. http://dx.doi.org/10.1175/jhm-362.1.
Testo completoAbstract (sommario):
Abstract Numerical Weather Prediction (NWP) and climate models are sensitive to evapotranspiration at the land surface. This sensitivity requires the prediction of realistic surface moisture and heat fluxes by land surface models that provide the lower boundary condition for the atmospheric models. This paper compares simulations of a stand-alone version of the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface scheme, or the Viterbo and Beljaars scheme (VB95), with various soil and vegetation parameter sets against soil moisture observations across the Murrumbidgee River catchment in southeast Australia. The study is, in part, motivated by the adoption of VB95 as the operational land surface scheme by the Australian Bureau of Meteorology in 1999. VB95 can model the temporal fluctuations in soil moisture, and therefore the moisture fluxes, fairly realistically. The monthly model latent heat flux is also fairly insensitive to soil or vegetation parameters. The VB95 soil moisture is sensitive to the soil and, to a lesser degree, the vegetation parameters. The model exhibits a significant (generally wet) bias in the absolute soil moisture that varies spatially. The use of the best Australia-wide available soils and vegetation information did not improve VB95 simulations consistently, compared with the original model parameters. Comparisons of model and observed soil moistures revealed that more realistic soil parameters are needed to reduce the model soil moisture bias. Given currently available continent-wide soils parameters, any initialization of soil moisture with observed values would likely result in significant flux errors. The soil moisture bias could be largely eliminated by using soil parameters that were derived directly from the actual soil moisture observations. Such parameters, however, are only available at very few point locations.
14
Higgisson, William, Dianne Gleeson, Linda Broadhurst e Fiona Dyer. "Genetic diversity and gene flow patterns in two riverine plant species with contrasting life-history traits and distributions across a large inland floodplain". Australian Journal of Botany 68, n. 5 (2020): 384. http://dx.doi.org/10.1071/bt20074.
Testo completoAbstract (sommario):
Gene flow is a key evolutionary driver of spatial genetic structure, reflecting demographic processes and dispersal mechanisms. Understanding how genetic structure is maintained across a landscape can assist in setting conservation objectives. In Australia, floodplains naturally experience highly variable flooding regimes that structure the vegetation communities. Flooding plays an important role, connecting communities on floodplains and enabling dispersal via hydrochory. Water resource development has changed the lateral-connectivity of floodplain-river systems. One possible consequence of these changes is reduced physical and subsequent genetic connections. This study aimed to identify and compare the population structure and dispersal patterns of tangled lignum (Duma florulenta) and river cooba (Acacia stenophylla) across a large inland floodplain using a landscape genetics approach. Both species are widespread throughout flood prone areas of arid and semiarid Australia. Tangled lignum occurs on floodplains while river cooba occurs along rivers. Leaves were collected from 144 tangled lignum plants across 10 sites and 84 river cooba plants across 6 sites, on the floodplain of the lower and mid Lachlan River, and the Murrumbidgee River, NSW. DNA was extracted and genotyped using DArTseq platforms (double digest RADseq). Genetic diversity was compared with floodplain-river connection frequency, and genetic distance (FST) was compared with river distance, geographic distance and floodplain-river connection frequency between sites. Genetic similarity increased with increasing floodplain-river connection frequency in tangled lignum but not in river cooba. In tangled lignum, sites that experience more frequent flooding had greater genetic diversity and were more genetically homogenous. There was also an isolation by distance effect where increasing geographic distance correlated with increasing genetic differentiation in tangled lignum, but not in river cooba. The distribution of river cooba along rivers facilitates regular dispersal of seeds via hydrochory regardless of river level, while the dispersal of seeds of tangled lignum between patches is dependent on flooding events. The genetic impact of water resource development may be greater for species which occur on floodplains compared with species along river channels.
15
Chen, Xiang Yang. "Quaternary sedimentation, parna, landforms, and soil landscapes of the Wagga Wagga 1 : 100 000 map sheet, south-eastern Australia". Soil Research 35, n. 3 (1997): 643. http://dx.doi.org/10.1071/s96071.
Testo completoAbstract (sommario):
The Wagga Wagga 1 : 100 000 map sheet is on the Western Slopes of southern New South Wales. The regional topography changes from hills in the east and south-east to gently sloping rises and alluvial plains in the west. Aeolian clays (parna) form a consistent clay regolith regardless of the underlying geology in the gently sloping areas. In some alluvial plains and on some lower hill slopes, the surficial sediments contain a significant portion of reworked parna. In hilly areas, parna is poorly preserved except on some remnant ancient land surfaces, such as dissected plateaux and piedmont plains. The soil pattern in the area is well controlled by landform processes and history. On relatively steep hill slopes, locally derived materials from weathering of bedrock are usually the dominant components of the soils, and geology is the dominant factor controlling soil distribution. In contrast, the Murrumbidgee high floodplain is covered by uniform silty clay with deep clayey soils (brown/grey Dermosols). Before the mid-Holocene, the alluvium mainly comprised sands and gravels, which were reworked by wind forming sand sheets and sand mounds (source-bordering dunes) on which deep sandy soils (Rudosols) now occur. The sediments and soils on the alluvial plains of local streams vary according to their distance from the source area and the flooding frequency. Areas considered to be mantled by parna, uniform red clayey soils (haplic red Kandosols/Chromosols) occur. Although the distribution pattern of the soils is controlled by the landform evolution, the relationships between soil morphological properties and topography are not readily quantified. On the alluvial and gently sloping landforms, soil properties usually show little change even though slope gradient and slope length vary. Some soils, e.g. the Rudosols on the sand sheets, rarely show any topographic features which may indicate their presence. In limited areas, e.g. on steeper hills formed on metasedimentary rock, the soil properties vary with changes in topographic parameters (slope gradient and slope length).
16
Batten, G. D., K. M. Marr e L. G. Lewin. "The effect of nitrogen fertiliser on yield, nitrogen and mineral elements in Australian brown rice". Australian Journal of Experimental Agriculture 39, n. 7 (1999): 873. http://dx.doi.org/10.1071/ea98033.
Testo completoAbstract (sommario):
Summary. The average yield of rice crops grown by the 2300 producers in southern Australia has ranged from 6.5 to 9.4 t/ha over the last 5 years. Average yields in the northern Murrumbidgee Irrigation Area have exceeded 10 t/ha in several of these years with individual producers attaining yields greater than 12 t/ha. Further increases in yield are expected with new genotypes, such as Namaga released in 1997. These high yielding crops require access to large amounts of nitrogen (and other elements) from the soil and fertilisers. Inputs of other nutrients are relatively minor and limited to phosphorus (P), sulfur (S) and zinc (Zn). In the current study, we evaluate the relations between yield increase due to nitrogen (N) fertiliser applications, and the rate of removal of elements by medium and long-grain genotypes. Some significant differences were found between genotypes in the concentration and accumulation of some minerals. In the 1993–94 experiment, the long-grain genotype Langi yielded higher and had higher mineral concentrations than Pelde, the lower-yielding genotype it replaced. However, no consistent relationships emerged between genotype, yield and mineral concentration or accumulation. Nitrogen applications caused significant increases in yield, grain nitrogen and some mineral concentrations. In the 1992–93 and 1993–94 experiments, 125 kg and 100 kg nitrogen fertiliser increased yield by 63% and 71% (from 6.8 to 11.1 t/ha and from 5.9 to 10.1 t/ha), respectively. The same N application rates increased the nitrogen concentration in the grain from 12.9 g/kg to 14.5 g/kg in 1992–93, and from 11.4 g/kg to 12.6 g/kg in 1993–94. Grain S was significantly increased in 1992–93 from 1.04 to 1.21 g/kg, and from 0.82 to 0.94 g/kg in 1993–94. The concentrations of grain Mn also increased significantly with N application in the 1993–94 season. Total accumulation of all minerals (except B and Na in 1992–1993 and Cu in 1993–1994) increased with N application. Yield increase, driven by N fertiliser, was the major influence on increased export of N, S, P, K, Mg, Ca, Fe, Mn and Zn from the soil.
17
Sivapalan, Siva, Graeme Batten, Ashantha Goonetilleke e Serge Kokot. "Yield performance and adaptation of some Australian-grown rice varieties through multivariate analysis". Australian Journal of Agricultural Research 58, n. 9 (2007): 874. http://dx.doi.org/10.1071/ar06357.
Testo completoAbstract (sommario):
Rice breeders are involved in developing new varieties for a diverse range of production environments to increase average yields. Interpretation of performance of several varieties evaluated in a broad range of environments is usually affected by variety × environment interactions. Application of multivariate analyses, especially multi-criteria decision making (MCDM) methods in variety × environment interaction studies can benefit interpretation of yield performance and adaptation of varieties in response to different environments. The case study discussed in this paper highlights the significant advantages of using MCDM methods to overcome constraints imposed by having to investigate a large number of variables inherent in such analysis. The grain yield of 13 rice varieties with varying characteristics, grown in 4 different regions in southern New South Wales (NSW), Australia, during the 2000–06 growing seasons was analysed using classification techniques and preference ranking organization method for enrichment evaluation (PROMETHEE) analysis. Significant variety × environment interaction was found to influence the yield performance of individual varieties across a range of environmental conditions. Classification of environments and geometrical analysis for interactive aid (GAIA) plot of PROMETHEE analysis identified the Murrumbidgee Irrigation Area (MIA) and Coleambally Irrigation Area (CIA) as higher yielding regions compared with the Eastern Murray Valley (EMV) and Western Murray Valley (WMV). Turbid water and cold weather conditions are suggested to explain the lower yield obtained in the WMV environment. In terms of varieties, Amaroo and Opus were identified as widely adaptable to most of the environments, while Jarrah was the least adaptable. Illabong can be considered as best adapted to the EMV or WMV regions, while Paragon and Reiziq can be regarded as best adapted to the MIA and CIA regions. Partial and complete ranking showed the interrelationships between the varieties for their yield performance and adaptation across all environments. Amaroo, Illabong, and Opus were ranked as the most preferred varieties, while Koshihikari, Kyeema, and Jarrah were ranked as the least preferred ones. Partial pre-order with 13 classes from PROMETHEE I analysis identified varieties with similar characteristics and aided the selection of suitable alternative varieties. The outcomes from the analyses reported here allow rice varieties or genotypes to be rated for yield stability for a specific or a range of different environments.
18
Kaune, Alexander, Faysal Chowdhury, Micha Werner e James Bennett. "The benefit of using an ensemble of seasonal streamflow forecasts in water allocation decisions". Hydrology and Earth System Sciences 24, n. 7 (30 luglio 2020): 3851–70. http://dx.doi.org/10.5194/hess-24-3851-2020.
Testo completoAbstract (sommario):
Abstract. The area to be cropped in irrigation districts needs to be planned according to the allocated water, which in turn is a function of the available water resource. Initially conservative estimates of future (in)flows in rivers and reservoirs may lead to unnecessary reduction of the water allocated. Though water allocations may be revised as the season progresses, inconsistency in allocation is undesirable to farmers as they may then not be able to use that water, leading to an opportunity cost in agricultural production. We assess the benefit of using reservoir inflow estimates derived from seasonal forecast datasets to improve water allocation decisions. A decision model is developed to emulate the feedback loop between simulated reservoir storage and water allocations to irrigated crops and is evaluated using inflow forecasts generated with the Forecast Guided Stochastic Scenarios (FoGSS) model, a 12-month ensemble streamflow forecasting system. Two forcings are used to generate the forecasts: ensemble streamflow prediction – ESP (historical rainfall) – and POAMA (calibrated rainfall forecasts from the POAMA climate prediction system). We evaluate the approach in the Murrumbidgee basin in Australia, comparing water allocations obtained with an expected reservoir inflow from FoGSS against the allocations obtained with the currently used conservative estimate based on climatology as well as against allocations obtained using observed inflows (perfect information). The inconsistency in allocated water is evaluated by determining the total changes in allocated water made every 15 d from the initial allocation at the start of the water year to the end of the irrigation season, including both downward and upward revisions of allocations. Results show that the inconsistency due to upward revisions in allocated water is lower when using the forecast datasets (POAMA and ESP) compared to the conservative inflow estimates (reference), which is beneficial to the planning of cropping areas by farmers. Overconfidence can, however, lead to an increase in undesirable downward revisions. This is more evident for dry years than for wet years. Over the 28 years for which allocation decisions are evaluated, we find that the accuracy of the available water estimates using the forecast ensemble improves progressively during the water year, especially 1.5 months before the start of the cropping season in November. This is significant as it provides farmers with additional time to make key decisions on planting. Our results show that seasonal streamflow forecasts can provide benefit in informing water allocation policies, particularly by earlier establishing final water allocations to farmers in the irrigation season. This allows them to plan better and use water allocated more efficiently.
19
Speer, Milton S., L. M. Leslie, S. MacNamara e J. Hartigan. "From the 1990s climate change has decreased cool season catchment precipitation reducing river heights in Australia’s southern Murray-Darling Basin". Scientific Reports 11, n. 1 (9 agosto 2021). http://dx.doi.org/10.1038/s41598-021-95531-4.
Testo completoAbstract (sommario):
AbstractThe Murray-Darling Basin (MDB) is Australia’s major agricultural region. The southern MDB receives most of its annual catchment runoff during the cool season (April–September). Focusing on the Murrumbidgee River measurements at Wagga Wagga and further downstream at Hay, cool season river heights are available year to year. The 27-year period April–September Hay and Wagga Wagga river heights exhibit decreases between 1965 and 1991 and 1992–2018 not matched by declining April-September catchment rainfall. However, permutation tests of means and variances of late autumn (April–May) dam catchment precipitation and net inflows, produced p-values indicating a highly significant decline since the early 1990s. Consequently, dry catchments in late autumn, even with average cool season rainfall, have reduced dam inflows and decreased river heights downstream from Wagga Wagga, before water extraction for irrigation. It is concluded that lower April–September mean river heights at Wagga Wagga and decreased river height variability at Hay, since the mid-1990s, are due to combined lower April–May catchment precipitation and increased mean temperatures. Machine learning attribute detection revealed the southern MDB drivers as the southern annular mode (SAM), inter-decadal Pacific oscillation (IPO), Indian Ocean dipole (IOD) and global sea-surface temperature (GlobalSST). Continued catchment drying and warming will drastically reduce future water availability.