This project was undertaken by consultant WMAwater for Federation Council. The final report was issued on 21 August 2024. It was one of the recommended actions arising from the 2022 Federation Villages Floodplain Risk Management Study and Plan.

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

The Wollombi Flood Study Review and Model Upgrade completed in 2010 represents the initial stage in the floodplain management process and establishes the basis for the current floodplain risk management study. The objectives of the Wollombi Floodplain Risk Management Study are to:  Identify and assess measures for the mitigation of existing flood risk;  Identify and assess planning and development controls to reduce future flood risks; and  Present a recommended floodplain management plan that outlines the best possible measures to reduce flood damages in the Wollombi locality. This report documents the Floodplain Risk Management Study and presents a recommended Floodplain Risk Management Plan for the Wollombi Village.

A Floodplain Risk Management Study and Plan (FRMS&P) for the Beverley Park catchment has been prepared by Cardno Lawson Treloar for Kogarah Council. The FRMS&P identify and examine options for the management of flooding within the Beverley Park catchment floodplain and is prepared in accordance with the NSW Government Floodplain Development Manual (2005). A locality plan can be found in Figure 1.1. The outline of the study area can be found in Figure 1.2. Study Context This study consists of the two stages of the multiple stages of the Floodplain Management process which includes:,

This report documents the Burrill Lake 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 the Burrill Lake catchment are to be managed in the future.

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.

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:,

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.

The Murrumburrah Flood Study (Reference 1), the first stage of the management process was completed in December 2019. The Murrumburrah Floodplain Risk Management Study and Plan constitutes the second and third stage of the management process for the catchment. This study has been prepared by WMAwater for Hilltops Council and was undertaken to provide the basis for future management of flood liable lands within the study area. This report has been prepared with financial assistance from the NSW Government through its Floodplain Management Program. This document does not necessarily represent the opinions of the NSW Government or the Department of Planning, Industry and the Environment. The Murrumburrah Flood Study provided information about existing flood risk in the Currawong Creek catchment, which is also known locally as Murrimboola Creek. Flood modelling tools were developed In the Flood Study that can be used by Council for decision-making about land-use planning, and in future studies such as the current Murrumburrah Floodplain Risk Management Study and Plan to assess the effectiveness of potential measures to reduce flood risk.

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.