Land clearance and river salinisation in the western Murray Basin, Australia

Allison, G.B.; Cook, Peter G.; Barnett, Steve; Walker, Glen; Jolly, Ian; Hughes, M.W.

doi:10.1016/0022-1694(90)90030-2

Cited by 277 publications

(177 citation statements)

References 18 publications

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“…This is a common observa- tion in Australian catchments, largely attributed to high rates of evapotranspiration that concentrate cyclic salts in the unsaturated zone, thereby increasing the salinity of subsurface water before it discharges into streams (e.g. Allison et al, 1990;Cartwright et al, 2004;Bennetts et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Time series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream

Duvert

Stewart

Cendón

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract.A major limitation to the assessment of catchment transit time (TT) stems from the use of stable isotopes or chloride as hydrological tracers, because these tracers are blind to older contributions. Yet, accurately capturing the TT of the old water fraction is essential, as is the assessment of its temporal variations under non-stationary catchment dynamics. In this study we used lumped convolution models to examine time series of tritium, stable isotopes and chloride in rainfall, streamwater and groundwater of a catchment located in subtropical Australia. Our objectives were to determine the different contributions to streamflow and their variations over time, and to understand the relationship between catchment TT and groundwater residence time. Stable isotopes and chloride provided consistent estimates of TT in the upstream part of the catchment. A young component to streamflow was identified that was partitioned into quickflow (mean TT ≈ 2 weeks) and discharge from the fractured igneous rocks forming the headwaters (mean TT ≈ 0.3 years). The use of tritium was beneficial for determining an older contribution to streamflow in the downstream area. The best fits between measured and modelled tritium activities were obtained for a mean TT of 16-25 years for this older groundwater component. This was significantly lower than the residence time calculated for groundwater in the alluvial aquifer feeding the stream downstream (≈ 76-102 years), emphasising the fact that water exiting the catchment and water stored in it had distinctive age distributions. When simulations were run separately on each tritium streamwater sample, the TT of old water fraction varied substantially over time, with values averaging 17 ± 6 years at low flow and 38 ± 15 years after major recharge events. This counterintuitive result was interpreted as the flushing out of deeper, older waters shortly after recharge by the resulting pressure wave propagation. Overall, this study shows the usefulness of collecting tritium data in streamwater to document short-term variations in the older component of the TT distribution. Our results also shed light on the complex relationships between stored water and water in transit, which are highly non-linear and remain poorly understood.

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Section: Discussionmentioning

confidence: 99%

Time series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream

Duvert

Stewart

Cendón

et al. 2016

Hydrol. Earth Syst. Sci.

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“…Therefore, it is expected that the substitution of permanent or perennial plants by annual crops may reduce ET rates, and eventually increase groundwater level because of a shortened growing period. In Australia, Allison et al (1990), Ward et al (2006) and Ferdowsian and Bee (2006) reported that the broad-scale clearing of perennial vegetation and its replacement by annual crops and annual pastures has resulted in rising groundwater levels. An additional aspect that may restrain ET once the onset of floods has taken place is the fact that land with the water Table close to the surface (e.g.…”

Section: The Potential Effect Of Cultivation On Floodingmentioning

confidence: 99%

The dynamics of cultivation and floods in arable lands of Central Argentina

Viglizzo

Jobbágy

Carreño

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. Although floods in watersheds have been associated with land-use change since ancient times, the dynamics of flooding is still incompletely understood. In this paper we explored the relations between rainfall, groundwater level, and cultivation to explain the dynamics of floods in the extremely flat and valuable arable lands of the Quinto river watershed, in central Argentina. The analysis involved an area of 12.4 million hectare during a 26-year period , which comprised two extensive flooding episodes in 1983-1988 and 1996-2003. Supported by information from surveys as well as field and remote sensing measurements, we explored the correlation among precipitation, groundwater levels, flooded area and land use. Flood extension was associated to the dynamics of groundwater level. While no correlation with rainfall was recorded in lowlands, a significant correlation (P <0.01) between groundwater and rainfall in highlands was found when estimations comprise a time lag of one year. Correlations between groundwater level and flood extension were positive in all cases, but while highly significant relations (P <0.01) were found in highlands, non significant relations (P >0.05) predominate in lowlands. Our analysis supports the existence of a cyclic mechanism driven by the reciprocal influence between cultivation and groundwater in highlands. This cycle would involve the following stages: (a) cultivation boosts the elevation of groundwater levels through decreased evapotranspiration; (b) as groundwater level rises, floods spread causing a decline of land cultivation; (c) flooding propitiates higher evapotranspiration Correspondence to: E. F. Viglizzo (evigliz@cpenet.com.ar) favouring its own retraction; (d) cultivation expands again following the retreat of floods. Thus, cultivation would trigger a destabilizing feedback self affecting future cultivation in the highlands. It is unlikely that such sequence can work in lowlands. The results suggest that rather than responding directly and solely to the same mechanism, floods in lowlands may be the combined result of various factors like local rainfall, groundwater level fluctuations, surface and subsurface lateral flow, and water-body interlinking. Although the hypothetical mechanisms proposed here require additional understanding efforts, they suggest a promising avenue of environmental management in which cultivation could be steered in the region to smooth the undesirable impacts of floods.

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“…Indeed, there are dramatic examples of unintended hydrologic consequences associated with a change in woody vegetation cover. For example, large-scale conversion of eucalyptus shrublands to cultivated farmlands in southern Australia led to a rise in groundwater tables (with increased soil salinity as an unfortunate byproduct) (Allison et al 1990;Walker et al 2002). Conversely, Jobbagy and Jackson (2004) documented a decline in groundwater recharge in the humid Argentine Pampas following afforestation.…”

Section: Emerging Issues For Ecohydrology Research In Rangelandsmentioning

confidence: 99%

Emerging Issues in Rangeland Ecohydrology: Vegetation Change and the Water Cycle

Wilcox

Thurow

2006

REM

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Rangelands have undergone-and continue to undergo-rapid change in response to changing land use and climate. A research priority in the emerging science of ecohydrology is an improved understanding of the implications of vegetation change for the water cycle. This paper describes some of the interactions between vegetation and water on rangelands and poses 3 questions that represent high-priority, emerging issues: 1) How do changes in woody plants affect water yield? 2) What are the ecohydrological consequences of invasion by exotic plants? 3) What ecohydrological feedbacks play a role in rangeland degradation processes? To effectively address these questions, we must expand our knowledge of hydrological connectivity and how it changes with scale, accurately identify ''hydrologically sensitive'' areas on the landscape, carry out detailed studies to learn where plants are accessing water, and investigate feedback loops between vegetation and the water cycle.

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Land clearance and river salinisation in the western Murray Basin, Australia

Cited by 277 publications

References 18 publications

Time series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream

Time series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream

The dynamics of cultivation and floods in arable lands of Central Argentina

Emerging Issues in Rangeland Ecohydrology: Vegetation Change and the Water Cycle

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