Flood Management Plan - Shire of Yarra Ranges
Flood Management Plan - Shire of Yarra Ranges
Flood Management Plan - Shire of Yarra Ranges
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The extents for the 1% AEP event have been incorporated into the <strong>Shire</strong> <strong>of</strong><strong>Yarra</strong> <strong>Ranges</strong> <strong>Plan</strong>ning Scheme as a Land Subject to Inundation Overlay(LSIO) across the floodplains <strong>of</strong> the creeks and as a Special Building Overlay(SBO) along the overflow paths <strong>of</strong> main drains.The existing flood overlays are constantly subject to change. Melbourne Wateris responsible for maintaining and updating the various flood overlays for theareas greater than 60 ha. The LSIO and SBO may change for various reasons:• Over time, as more <strong>of</strong> the municipality is mapped the flood extents willincrease.• As more advanced methods <strong>of</strong> modelling and/or mapping aredeveloped, the flood extents may change.• New flood areas may be introduced as <strong>Yarra</strong> <strong>Ranges</strong> continues todevelop and further flood investigations are undertaken.• Furthermore, an LSIO overlay may be reclassified as an SBO overlay if adrainage system is installed through the flood prone area, generally toserve a new development.Such investigations require an update <strong>of</strong> the existing SBO and LSIO in theplanning schemes (planning scheme amendment). Additional propertiesaffected by the new flood extent need to be included under either an LSIO orSBO overlay.Melbourne Water has also surveyed many <strong>of</strong> the floor levels within the floodmapped catchments to categorise the building floor levels that are subject toinundation. Recently, Melbourne Water and the DSE in collaboration withmany <strong>of</strong> the local Councils have completed a LiDAR survey <strong>of</strong> MelbourneWater’s area <strong>of</strong> responsibility which included the <strong>Shire</strong>.Melbourne Water’s pipe and pit GIS information shows invert levels, pipesizes, pit types and pit invert levels in all locations and is generally wellbacked up by ‘as constructed’ plans <strong>of</strong> all assets. <strong>Yarra</strong> <strong>Ranges</strong>’ pipe and pitGIS information shows the size <strong>of</strong> the asset and maintenance responsibility inall locations as well as the length, inverts and grades. Together, the availableasset information is considered to be complete and suitable for use in anyfuture mapping projects.8.2.2 Proposed Mapping ProgramFuture flood mapping to be completed by Melbourne Water is based on anumber <strong>of</strong> factors including the presence <strong>of</strong> existing mapping, the quality <strong>of</strong>existing mapping and the safety risks <strong>of</strong> potential flooding. Currently, the Little<strong>Yarra</strong> from the confluence with the <strong>Yarra</strong> River through to Blackwood Creek isMelbourne Water <strong>Shire</strong> <strong>of</strong> <strong>Yarra</strong> <strong>Ranges</strong> <strong>Flood</strong> <strong>Management</strong> <strong>Plan</strong> 51