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Information Sheet
(catchment)
C7 - Rainfall Overview
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1. General Description
The Upper Parramatta River Catchment Trust and the Bureau
of Meteorology operate a network of rain gauges throughout
the catchment. A pan evaporation monitoring station is at
Prospect Reservoir.
(Pan Evaporation – a pan of standard dimension
and installation is used to measure the rate of evaporation.
This is calculated as the difference in surface water levels
in the pan with adjustments
made for any daily rainfall.)
The following table shows the average monthly rainfall for
four sites.
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Welsford Street, Merrylands
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Wilson Ave, Winston Hills
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Masons Drive, North Parramatta
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Prospect Dam, Prospect.
The averages were calculated from data collected continuously
between 1969 and 1996. Average Pan evaporation rates were
measured on Prospect Reservoir.
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Stormclouds are a common sight over Parramatta
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Fig C7.1 Average Rainfall and Pan Evaporation Rates for the
Upper Parramatta River Catchment
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Month
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Average Rainfall
(mm)
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Average pan Evaporation (mm)
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January
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110.6
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169.0
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February
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119.2
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138.7
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March
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120.3
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125.4
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April
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92.6
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90.3
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May
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74.3
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64.0
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June
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80.6
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51.5
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July
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43.0
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57.7
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August
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55.0
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81.2
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September
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55.6
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107.1
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October
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70.1
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135.4
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November
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96.5
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149.4
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December
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71.3
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182.8
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Total
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989.1
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1352.5
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2. Map
Refer to Map 3 - Upper Parramatta River Rain Gauge Map for locations
of rain gauges throughout the catchment.
3. Distribution
 Rainfall measurements between 1969 and 1996
show that there is a significant variation in the rainfall intensity
and average in the catchment. Rainfall varies with elevation in
the catchment. The lower lying areas to the west and southwest of
the catchment are on the fringe of the Cumberland Plain. These areas
receive rainfall below 900mm per year while the higher areas in
the catchment such as Pennant Hills receive over 1000mm per annum.
This can have a substantial influence on the types of vegetation
and flow rates found in creeks. (Streamwatch Report 1999-2001)
4. Reasons for Distribution
Topography, elevation and vegetation play an important role in
determining the rainfall characteristics of a given area. There
is a significant difference between the two main zones within the
Upper Parramatta River Catchment. The Baulkham Hills area is of
a higher elevation and has a greater proportion of bushland vegetation,
which is thought to help trigger precipitation. In comparison, the
western reaches of the catchment are lower lying and have much more
sparse vegetation, with no predominant hills or landforms to induce
rain.
5. Other Resources and Links
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Upper Parramatta River Catchment Trust www.uprct.nsw.gov.au
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Streamwatch Report 1999-2001 www.uprct.nsw.gov.au
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Department of Land & Water Conservation www.dlwc.nsw.gov.au
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Sydney Water www.sydneywater.com.au
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Parramatta City Council www.parracity.nsw.gov.au
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Baulkham Hills Shire Council www.baulkhamhills.nsw.gov.au
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Holroyd City Council www.holroyd.nsw.gov.au
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Blacktown City Council www.blacktown.nsw.gov.au
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Bureau of Meteorology www.bom.gov.au
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