Artificial maintenance of groundwater levels to protect carbonate cave fauna,Yanchep,Western Australia

2013 ◽  
pp. 51-64 ◽  
Keyword(s):  
Western Australia ◽  
Groundwater Levels ◽  
Cave Fauna

Effects of salinisation on riparian plant communities in experimental catchments on the Collie River, Western Australia

2003 ◽  
Vol 51 (6) ◽  
pp. 667 ◽  
Author(s):  
A. J. Lymbery ◽  
R. G. Doupé ◽  
N. E. Pettit
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Western Australia ◽  
Soil Salinity ◽  
Riparian Vegetation ◽  
Plant Species Richness ◽  
Perennial Herb ◽  
Groundwater Levels ◽  
Riparian Plant Communities ◽  
Riparian Plant

Although the salinisation of streams has long been recognised as one of Western Australia's most serious environmental and resource problems, there is very little published information on the effects of salinisation on riparian flora and fauna. We studied riparian vegetation in three experimental catchments on the Collie River in Western Australia. The catchments are situated within a 5-km area of state forest and are geologically and botanically similar, but differ in the extent of clearing, groundwater levels and stream salinity. In each catchment, transects were taken perpendicular to the direction of streamflow, and 4-m2 quadrats taken along each transect. Within each quadrat, soil salinity was measured, all plants were identified to species level and percentage cover estimated. The catchments differed significantly in soil salinity, with salinity being greatest in the most extensively cleared catchment and increasing towards the floor of the valley. Plant-species richness, species diversity and species composition were significantly related to soil salinity, both among catchments and among quadrats within the most extensively cleared catchment. Plant-species richness and diversity decreased with increasing soil salinity, an effect that may be partly due to a decline in perennial herb and shrub species. This may have an impact on other components of the riparian ecosystem.

Valley reforestation to lower saline groundwater tables - Results from Stene Farm, Western-Australia

Soil Research ◽  
1991 ◽  
Vol 29 (5) ◽  
pp. 635 ◽  
Author(s):  
NJ Schofield ◽  
MA Bari
Keyword(s):  
Western Australia ◽  
Tree Species ◽  
Soil Surface ◽  
Groundwater Table ◽  
Native Forest ◽  
Groundwater Salinity ◽  
Saline Groundwater ◽  
Groundwater Levels ◽  
Salinity Increase ◽  
The 1950S

Dense planting of selected trees in salt-affected valley floors and non-saline adjacent slopes has been evaluated as one strategy for controlling rising saline groundwater under agriculture. Of the 127 ha experimental catchment, 44% had been cleared of native forest in the 1950s. Valley reforestation covering 35% of the cleared area took place in 1979, by which time a groundwater of 5300 mg L-1 TSS had risen to within 0.5 m of the soil surface. The eucalypt reforestation was successful in lowering the groundwater table by 1.5 m by 1989, whilst groundwater levels under nearby pasture had risen by 1.8 m. The groundwater salinity beneath reforestation decreased by 30% over the study period, allaying fears of a detrimental groundwater salinity increase brought about by transpirative concentration. Measures such as replanting failed areas, implementing agricultural recharge control or selecting higher water using tree species would improve the performance of the valley reforestation strategy.

Evaluation of the impacts of deep open drains on groundwater levels in the wheatbelt of Western Australia

2004 ◽  
Vol 55 (11) ◽  
pp. 1159 ◽  
Author(s):  
Riasat Ali ◽  
Tom Hatton ◽  
Richard George ◽  
John Byrne ◽  
Geoff Hodgson
Keyword(s):  
Western Australia ◽  
Discharge Rate ◽  
Soil Surface ◽  
Extreme Rainfall ◽  
Water Levels ◽  
Extreme Rainfall Event ◽  
Wet Season ◽  
Initial Water ◽  
Groundwater Levels ◽  
The Impact

Abstract. Over one million hectares of the wheatbelt of Western Australia (WA) are affected by secondary salinisation and this area is expected to increase to between 3 and 5 million hectares if current trends continue. Deep open drains, as an engineering solution to dryland salinity, have been promoted over the past few decades; however, the results of initial experiments were variable and no thorough analysis has been done. This research quantifies the effects of deep open drains on shallow and deep groundwater at farm and subcatchment level. Analysis of rainfall data showed that the only dry year (below average rainfall) after the construction of drainage in the Narembeen area of WA (in 1998 and 1999) was 2002. The dry year caused some decline in groundwater levels in the undrained areas but had no significant impact in the drained areas. The study found that the effect of drains on the groundwater levels was particularly significant if the initial water levels were well above the drain bed level, permeable materials were encountered, and drain depth was adequate (2.0–3.0 m). Visual observations and evidence derived from this study area suggested that if the drain depth cut through more permeable, macropore-dominated siliceous and ferruginous hardpans, which exist 1.5–3 m from the soil surface, its efficiency exceeded that predicted by simple drainage theory based on bulk soil texture. The effect of drains often extended to distances away (>200 m) from the drain. Immediately following construction, drains had a high discharge rate until a new hydrologic equilibrium was reached. After equilibrium, flow largely comprised regional groundwater discharge and was supplemented by quick responses driven by rainfall recharge. Comparison between the hydrology of the drained and undrained areas in the Wakeman subcatchment showed that, in the valley floors of the drained areas, the water levels fluctuated mainly between 1.5 and 2.5 m of the soil surface during most of the year. In the valley floors of the undrained areas, they fluctuated between 0 and 1 m of the soil surface. The impact of an extreme rainfall event (or unusual wet season) on drain performance was predicted to vary with distance from the drain. Within 100 m from the drain, water levels declined relatively quickly, whereas it took a year before the water levels at 200–300 m away from the drain responded. The main guidelines that can be recommended based on the results from this study are the drain depth and importance of ferricrete layer. In order to be effective, a drain should be more than 2 m deep and it should cut through the ferricrete layer that exists in many landscapes in the wheatbelt.

Groundwater levels under climate change in the Gnangara system, Western Australia

2013 ◽  
Vol 4 (1) ◽  
pp. 52-62 ◽  
Author(s):  
Adrian H. Gallardo
Keyword(s):  
Climate Change ◽  
Water Table ◽  
Western Australia ◽  
Water Levels ◽  
Good Correspondence ◽  
Groundwater Levels ◽  
Aquifer Systems ◽  
The Status ◽  
Rainfall Reduction ◽  
The Impact

The Gnangara system is the main source of freshwater for Perth, Western Australia. However, aquifers in the region are under severe stress due to a drying climate, intensive pumping and changes in land use. The aim of this study is to apply the mean rainfall cumulative deviation and Mann-Kendall analyses at 77 monitoring bores to investigate the response of the water table to key recharge components. This information is critical for setting new allocation limits and reviewing current policies in the region. Results show that overall there is a good correspondence between water levels and rainfall fluctuations. Areas of groundwater recharge are highly sensitive to climate change and have been severely affected by reduction in rainfall rates in recent years. Further, removal of pine plantations correlated well with a rise in groundwater levels although the effect seems to be temporary. The impact of pumping is mainly observed in vicinities of public-supply borefields. Elsewhere, water table trends show a relative stabilisation indicating that storage still exceeds the influence of rainfall reduction in areas dominated by through flow or groundwater discharge. The study contributes to update the status of the Gnangara groundwater resource, and provides new insights for the sustainable management of one of the main aquifer systems in Australia.

scholarly journals Modelling the effects of climate and land cover change on groundwater recharge in south-west Western Australia

2012 ◽  
Vol 16 (8) ◽  
pp. 2709-2722 ◽  
Author(s):  
W. Dawes ◽  
R. Ali ◽  
S. Varma ◽  
I. Emelyanova ◽  
G. Hodgson ◽  
...  
Keyword(s):  
Land Cover ◽  
Groundwater Recharge ◽  
Western Australia ◽  
Coastal Plain ◽  
Future Climate ◽  
Native Vegetation ◽  
Groundwater Levels ◽  
Swan Coastal Plain ◽  
South West ◽  
Recharge Rates

Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south-west Western Australia, provides approximately 60 percent of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15 percent. There is expected to be a reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A vertical flux manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on climate, land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In areas with land-use change, recharge rates have increased. Where rainfall has declined sufficiently, recharge rates are decreasing, and where compensating factors combine, there is little change to recharge. In the southwestern part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sand-dominated areas, there is little response to future climate change, because groundwater levels are shallow and much rainfall is rejected recharge. Where the combination of native vegetation and clayey surface soils restricts possible infiltration, recharge rates are very sensitive to reductions in rainfall. In the northern part of the study area, both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas, the recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry.

scholarly journals Modelling the effects of climate and land cover change on groundwater recharge in south-west Western Australia

2012 ◽  
Vol 9 (5) ◽  
pp. 6063-6099 ◽  
Author(s):  
W. Dawes ◽  
R. Ali ◽  
S. Varma ◽  
I. Emelyanova ◽  
G. Hodgson ◽  
...  
Keyword(s):  
Land Cover ◽  
Groundwater Recharge ◽  
Western Australia ◽  
Coastal Plain ◽  
Groundwater Resource ◽  
Annual Rainfall ◽  
Native Vegetation ◽  
Groundwater Levels ◽  
Swan Coastal Plain ◽  
South West

Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south west Western Australia, provides approximately 60% of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15%. There is expected to be a continuing reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A Vertical Flux Manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. These recharge estimates were accumulated on a daily basis for both observed and projected climate scenarios and used in a MODFLOW simulation with monthly stress periods. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In the Dandaragan Plateau to the north-east of Perth there has been groundwater level rise since the 1970s associated with land clearing, and with rainfall projected to reduce the least in this area the groundwater levels are estimated to continue to rise. Along the coastal zone north of Perth there is an interaction between projected rainfall decline and legislated removal to pine forests. This results in areas of increasing recharge and rising water levels into the future despite a drying climate signal. To the south of Perth city there are large areas where groundwater levels are close to the land surface and not expected to change more than 1m upward or downward over the next two decades; it is beyond the accuracy of the model to conclude any definite trend. In the south western part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sandy Swan (northern boundary) and Scott Coastal Plains (southern boundary) there is little response to future climates, because groundwater levels are shallow and much rainfall is rejected recharge. The profile dries out more in summer but this allows more rainfall to infiltrate in winter. Until winter recharge is insufficient to refill the aquifers these areas will not experience significant falls in groundwater levels. On the Blackwood Plateau however, the combination of native vegetation and clayey surface soils that restrict possible infiltration and recharge mean the area is very sensitive to climate change. With low capacity for recharge and low storage in the aquifers, small reductions in recharge can lead to large reductions in groundwater levels. In the northern part of the study area both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas the low recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry. In the Albany Area the groundwater resource is already over allocated, and the combination of existing permanent native vegetation with decreasing annual rainfall indicate reduced recharge. The area requires a reduction in groundwater abstraction to maintain the sustainability of the existing resource.

The influence on groundwater levels and salinity of a multi-specied tree plantation in the 500 mm rainfall region of south-western Australia

1994 ◽  
Vol 25 (2) ◽  
pp. 185-200 ◽  
Author(s):  
E.A.N. Greenwood ◽  
E.F. Biddiscombe ◽  
A.L. Rogers ◽  
J.D. Beresford ◽  
G.D. Watson
Keyword(s):  
Western Australia ◽  
Tree Plantation ◽  
Groundwater Levels ◽  
Rainfall Region

Explaining groundwater hydrographs: separating atypical rainfall events from time trends

Soil Research ◽  
2001 ◽  
Vol 39 (4) ◽  
pp. 861 ◽  
Author(s):  
Ruhi Ferdowsian ◽  
David J. Pannell ◽  
Clare McCarron ◽  
Arjen Ryder ◽  
Lisa Crossing
Keyword(s):  
Western Australia ◽  
Time Trends ◽  
Time Trend ◽  
Agricultural Land ◽  
Explanatory Power ◽  
Dryland Salinity ◽  
Rainfall Events ◽  
Groundwater Levels ◽  
Average Rainfall ◽  
Using Data

By 1994, an estimated 1.8 million hectares of cleared land in Western Australia was affected by secondary dryland salinity to some extent. The area affected is likely to double in the coming 20 years. The cause of this salinity is excessive recharge under traditional agriculture, leading to rising groundwater levels. Monitoring changes in groundwater levels is helpful in indicating the degree of threat to agricultural land and public assets. Many researchers have studied groundwater level rises and attempted to explain them statistically. We present an approach for statistically estimating trends in groundwater levels. The approach separates the effect of atypical rainfall events from the underlying time trend and the lag between rainfall and its impact on groundwater is explicitly represented. Rainfall is represented as an accumulation of deviations from average rainfall. Application of the approach is demonstrated using data from 49 bores in Jerramungup Shire, Western Australia. The approach provides high explanatory power, particularly for deeper bores.

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