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Probable Maximum Precipitation Study for the Clarence River Catchment

The Clarence River Valley in the north coast region of N.S.W. has a long history of flooding, especially at Grafton. In recent years, the urban areas of Grafton and South Grafton have been protected from moderate floods by the construction of levee banks. The levee bank is expected to provide protection up to approximately the 1 in 100 year level at Grafton and the 1 in 20 year level at South Grafton. Raising of the levees to higher levels has been suggested in previous studies. As part of the investigations relating to the levee bank proposals, the Public Works Department (PWD) commissioned Weatherex Meteorological Services Pty. Ltd. in September, 1983 to estimate the probable maximum precipitation for the Clarence River catchment.

The objective of the study was to estimate the probable extreme storm precipitation over the Clarence River catchment upstream from Grafton for periods up to 5 days. The Terms of Reference for the study, as set down by the Department, covered the following points:

  • Values of estimated maximum precipitation are to be derived by synoptic methods of storm maximisation, using both in-situ and transposed storms.
  • In addition, the generalised method developed by the Bureau of Meteorology is to be applied, using specific catchment adjustments for the Clarence system. For this purpose, the Clarence catchment is considered to be comparable with the Queensland Coastal Zone.

Additional Information

Field Value
Title Probable Maximum Precipitation Study for the Clarence River Catchment
Publication Date 1 November 1984
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Clarence Valley Council
Author/ Prepared by Weatherex Meteorological Services Pty Ltd
Publish date 1 July 2020
Update date 1 July 2020
Approval State Approved
Submitted for approval 2 July 2020
Submitted by Julia Muniz de Miranda Sa
Approved 2 July 2020
Approved by dstazic
Identifier 1ed48857-a96c-4553-80ee-545bb2ef3810