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Dealing with salinity in Wheatbelt Valleys - Department of Water

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agriculture) <strong>in</strong> various stages, the oldest be<strong>in</strong>g<br />

approximately 85 years ago, while the newest is<br />

25 years. Approximately 80% <strong>of</strong> the landscape has<br />

been cleared for agriculture. The rema<strong>in</strong><strong>in</strong>g remnant<br />

vegetation is <strong>in</strong> the form <strong>of</strong> Conservation<br />

Commission controlled Reserves, vacant Crown land<br />

and Road Reserves, <strong>with</strong> approximately 10%<br />

rema<strong>in</strong><strong>in</strong>g on farms.<br />

6320000<br />

6300000<br />

6280000<br />

6260000<br />

6240000<br />

600000<br />

600000<br />

Hydrology <strong>of</strong> the Area<br />

NYABING<br />

620000<br />

620000<br />

ONGERUP<br />

(<br />

640000<br />

640000<br />

Detailed hydrological studies <strong>of</strong> the P<strong>in</strong>grup town<br />

catchment through the Rural Towns Programme,<br />

and the M<strong>in</strong>elup Creek Catchment and Range Road<br />

Catchment through the Focus Catchment Process,<br />

have been completed.<br />

A drill<strong>in</strong>g project, which has placed piezometers and<br />

observation wells throughout the catchment, is <strong>in</strong><br />

place. These were drilled <strong>in</strong> 1997 to 1998 and are<br />

NHT funded. Lewis & Nelson (1994) concluded the<br />

follow<strong>in</strong>g about the area’s hydrology:<br />

PINGRUP<br />

Soils<br />

Morrell, Hatton and Curry<br />

The district consists <strong>of</strong> a large bank <strong>of</strong> salt lakes<br />

runn<strong>in</strong>g from south to north <strong>with</strong> slightly undulat<strong>in</strong>g<br />

lands surround<strong>in</strong>g these lakes. Soils vary from very<br />

sandy to heavy clay; all however are relatively<br />

shallow soils over a clay base (Figure 2).<br />

660000<br />

660000<br />

Figure 2: Lake Ch<strong>in</strong>ocup Soils Map<br />

– 3 –<br />

JERRAMUNGUP<br />

(<br />

680000<br />

LEGEND<br />

Towns<br />

Roads<br />

Subcatchments<br />

Soils 500k<br />

Loamy duplex<br />

Loamy earth<br />

Rocky or stony soils<br />

Sandy earth<br />

Shallow sandy duplex<br />

Wet soils<br />

680000<br />

• Average annual recharge under agriculture is <strong>in</strong><br />

the order <strong>of</strong> 5–50 mm. Coarse textured soils<br />

probably contribute most recharge to the<br />

catchment aquifers, but some areas <strong>with</strong> f<strong>in</strong>er<br />

textured soils are likely to be significant, even<br />

<strong>with</strong>out waterlogg<strong>in</strong>g conditions.<br />

• The water table is ris<strong>in</strong>g below many parts <strong>of</strong> the<br />

catchment at rates <strong>of</strong> about 10–30 cm/yr.<br />

• Episodic recharge result<strong>in</strong>g from flood events<br />

may contribute most <strong>of</strong> the recharge occurr<strong>in</strong>g<br />

below some parts <strong>of</strong> the valley floor. Major<br />

summer storms may contribute a significant<br />

6320000<br />

6300000<br />

6280000<br />

6260000<br />

6240000

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