construction and refurbishment of earthen irrigation channel banks

Data from Goulburn-Murray Water’s asset management information system, whichincludes the date of construction, condition rating and length of each channel, has beenused to estimate the average life of channel banks.The weighted average life of channel banks across Goulburn-Murray Water is estimatedto be 90 years for the banks of smaller distribution channels and 130 years for the banksof major supply channels. Refer to Table 9-1.Channel NameMain ChannelsYarrawonga Main ChannelEast Goulburn Main ChannelGoulburn-Waranga ChannelsWaranga Western Main ChannelTorrumbarry Bulk CarriersDistribution ChannelsShepparton AreaCentral Goulburn AreaRochester-Campaspe AreaPyramid-Boort AreaMurray Valley AreaTorrumbarry AreaEstimatedAverage Life(years)10010015013010085708510085100Table 9-1Estimated Earthen Channel Bank Average Lives - Goulburn-MurrayWaterThe investigations by Goulburn-Murray Water to determine the lives of its channel bankshighlighted the lack of understanding of the processes involved. It indicated that the rateof channel bank deterioration is not constant and more long-term research was requiredinto channel bank useful lives.A range of factors, as well as the interaction of these factors, affect channel bank livesand the rate of deterioration. These may include the following:• design criteria• size and width of bank• velocity of flow and flow history• age of channel• depth of channel• construction methods and quality control• bank material –soil type• usage history• environment• frequency and intensity of livestock access• aquatic fish and animal activity in the channel- carp• bank orientation relative to prevailing winds• operating practices and running levels• fluctuations in water level – magnitude and rate• maintenance regimes – past and current• extent and quality of refurbishmentConstruction and Refurbishment of Earthen Channel Banks August 2002 - Edition 1.0 9-4