The overall objective of this study is to develop a Floodplain Risk Management Study where management issues are assessed, management options are investigated and recommendations are made. Thereafter a Floodplain Risk Management Plan detailing how flood prone land within the study area is to be managed can be completed. The objectives of the Flood Risk Management Study are to:,

Study Objectives The key objective of this Flood Study is to develop computational models that can be used as the basis for a Floodplain Risk Management Study and Plan for the study area. The study is also to assist SCC to undertake flood-related planning decisions for existing and future developments. The study covers the Lake Wollumboola catchment and the Culburra Beach village catchment. The components of the study were to: collate available historical flood-related data; analyse of historical rainfall and lake level data; undertake a community consultation program; develop numerical models of flooding in the catchment and calibrate them to historical data; determine the flood behaviour including design flood levels, velocities and flood extents within the catchment; to determine provisional residential flood planning levels and flood planning area; to assess the sensitivity of flood behaviour to potential climate change effects such as Lake Wollumboola Flood Study WMAwater 150917_LakeWollumboola_FloodStudy_Final:24 September 2015 5 increases in rainfall intensities and sea level rise; and to assess the floodplain categories in accordance with Council policy and undertake provisional hazard mapping.

Complete report

This Floodplain Risk Management Study investigates what can be done to reduce or manage the effects of flooding in the catchment. The Floodplain Risk Management Plan recommends a mix of strategies to manage the risks of flooding. Using the merits-based approach advocated in the NSW State Government’s Floodplain Development Manual (2005) and in consultation with the community, Council and state agency stakeholders, a number of potential options for the management of flooding were identified. These options included: • flood modification measures; • property modification measures; and • emergency response measures. An extensive list of options was assessed against a range of criteria (technical, economic, environmental and social). Hydraulic modelling of some of the flood modification options was undertaken to provide a comprehensive analysis of those options that would involve significant capital expenditure.

This report documents the Lake Wyangan Floodplain Risk Management Study and Plan which investigates and presents a flood risk management strategy for the catchment. The study identifies the existing flooding characteristics and canvasses various measures to mitigate the effects of flooding. The end product is the Floodplain Management Plan, which describes how flood liable lands within Lake Wyangan are to be managed in the future.

Revised flood study and floodplain risk management Study and plan.

Preparation of a flood risk management study and plan including a flood study update for Eumungerie

AIMS OF THE CURRENT STUDY In broad terms, the current Floodplain Risk Management Study has investigated what can be done to minimise the effects of flooding in the Haslams Creek catchment and recommended a strategy in the form of a draft Floodplain Risk Management Plan. Specific objectives of the study include: a review of the results from the 1999 Flood Study; consideration of the potential for culvert blockages and associated flood impacts; the implementation of a community consultation strategy, to ensure community input is obtained at key times throughout the study; a description and quantification of the flood problems in the Haslams Creek catchment including the likely cost of flooding to the local community; the identification and assessment of potential floodplain risk management measures to reduce the risks and hazards of flooding; a detailed review of issues relating to planning and development controls within the floodplain. Don Fox Planning Pty Ltd has prepared a document entitled Report on Planning Issues as part of this study. It is reproduced in Appendix A. Included in this report, is a proposed draft Development Control Plan (DCP) entitled “Managing Our Flood Risks”; the development of a recommended draft Floodplain Risk Management Plan for the Haslams Creek catchment that outlines the best measures to reduce flood damage, based on environmental, social, economic, financial and engineering considerations.

Cessnock City Council has engaged Cardno (NSW/ACT) Pty Ltd to prepare the Black Creek Floodplain Risk Management Study and the Black Creek Floodplain Risk Management Plan in accordance with the NSW Government Floodplain Development Manual (NSW Government, 2005). Flooding in the catchment can pose a hazard to residents and businesses near the creeks, channels and overland flow paths. The purpose of this study is to identify and examine options for the management of flooding within the Black Creek catchment. The purpose of this plan is to document a strategy of suitable actions for implementation. The Black Creek catchment is located within the Cessnock Local Government Area (LGA) and comprises all urban areas including the Cessnock Central Business District (CBD) and surrounding suburbs. Black Creek has several tributaries, including Bellbird Creek, Lavender Creek, Limestone Creek, Kearsley Creek and Aberdare Creek. Other tributaries include the Oliver Street channel in South Cessnock and the East Cessnock Drain. These tributaries flow through rural areas towards Cessnock and generally comprise concrete lined trapezoidal channels in the urban areas. Given the numerous creeks converging in Cessnock, flooding has occurred regularly including in 1949, 1977, 1990, 1992 and 2007. As part of this study, the existing hydrological and hydraulic models developed as part of the Black Creek Flood Study (DHI, 2010) were extended to include areas outside of the Cessnock CBD where limited information on flooding behaviour existed including Bellbird, Mount View detention basin and surrounds and northeast of the CBD. Up-to-date ground survey information was collected in 2011 and was used to represent the terrain in the hydraulic model. Flood modelling was undertaken for seven design storm events ranging from the 20% Annual Exceedance Probability (AEP) event up to the Probable Maximum Flood (PMF) event in order to assess flood behaviour in the extended hydraulic model. A number of key differences from the DHI (2010) study resulted from the extension of the hydraulic model and incorporation of up-to-date survey information including a reduction in 1% AEP flood levels ranging from 0.2m to 0.5m along Bellbird Creek and a reduction in flood levels of 0.2m along East Cessnock Drain. The updated hydraulic model provides detailed information on flood behaviour and overland flow paths in the vicinity of Mount View detention basin and through the urban areas of Cessnock. The revised flood extents were adopted by Council in March 2014. An assessment was undertaken on the number of properties that would be subject to overground and overfloor flooding within the floodplain under various design storm events ranging from the 20% AEP event up to the PMF. Options to reduce or manage the effects of flooding in the catchment were investigated to manage the risks of flooding. Under the merits-based approach outlined in the NSW State Government’s Floodplain Development Manual (NSW Government, 2005) a number of potential options for the management of flooding were identified, namely: Flood modification measures (FM Options); Property modification measures (P Options); Emergency response modification measures (EM Options). An extensive list of options was assessed against a range of criteria (technical, economic, environmental and social) and hydraulic modelling of some of the flood mitigation options was undertaken to provide a comprehensive analysis of those options that would involve significant capital expenditure. The highest ranking options identified by the multi criteria analysis include: FM5, proposed bund/flood wall east of Sixth Street properties and railway line in South Cessnock; EM4, Public awareness and education; EM5, Flood warning signs at critical locations; P6, Land Swap; P3, House Raising; P4, House Rebuilding; A number of structural options assessed were not considered viable either due to: adverse impacts on flood levels such as Option FM2 (A

The recommended Floodplain Risk Management Plan for the Griffith CBD catchments has been prepared in accordance with the NSW Floodplain Development Manual (Reference 6) and: * Is based on a comprehensive and detailed evaluation of all factors that affect and are affected by the use of flood prone land; and * Provides a long-term path for the future development of the community. Griffith is located approximately 450 km north of Melbourne and 560 km west of Sydney in the heart of the Murrumbidgee Irrigation Area (MIA). The CBD and residential areas of Griffith are located at the base of the McPherson Ranges (see Figure 1). Griffith and its surrounding villages of Yenda, Yoogali, Hanwood, Bilbul and Beelbangera lie within the Main Drain “J” catchment, which together with its network of drainage channels delivers runoff to Mirrool Creek. The Griffith CBD catchment has an area of approximately 9 km2. The upper part of the catchment is steep and covered in scattered timber and bushland. South of the bushland area the urban area begins and continues south to Wakaden St and the Temora-Roto Railway Line. This area is predominantly low density residential development. Griffith CBD lies to the south of the railway line, and is characterised by commercial and light industrial land uses. At the downstream extents of the CBD is the Main Canal which is raised above normal ground levels and is consequently a substantial obstruction to overland flow. The City of Griffith is not located on the banks of a major river system and therefore does not experience mainstream flooding as occurs at other centres within the Murrumbidgee River catchment for example Wagga Wagga. However, Griffith and its surrounding areas are affected by high volume rainfall events and also from flooding from the Main Drain J system. In the past, frequent flooding has occurred throughout the commercial areas of Griffith including Yambil Street, even in small rainfall events less than the 6 month ARI for example. Studies have indicated that this flooding has been due to a combination of catchment runoff, blockage and/or insufficient capacity of the sub-surface drainage systems and the associated siphon drainage systems, as well as the elevated railway and canal embankments that impede downstream overland flow paths. Within the study area flows are predominantly distributed and shallow at the upstream or northern sections of the CBD catchment and runoff generally ponds behind the various embankments that tend to be aligned normal to general flow direction such as the Main Canal and railway line, before being gradually discharged through the siphon outlets located under the Main Canal at the downstream boundary of the study area. The Flood Study (Reference 1) also found that the actual flow at the siphons was largely restricted by the upstream drainage system.