Goosepond Creek (Including Pioneer River) Flood Study
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GOOSEPOND CREEK (INCLUDING PIONEER RIVER) FLOOD STUDY Mackay Regional Council 9 October 2012 REPORT TITLE: Gooseponds Creek (including Pioneer River) Flood Study CLIENT: Mackay Regional Council REPORT NUMBER: 0500-01 O(rev 1) Revision Number Report Date Report Author Reviewer 0 3 September 2012 GR SM 1 9 October 2012 GR For and on behalf of WRM Water & Environment Pty Ltd Greg Roads Director LIMITATION: This advice has been prepared on the assumption that all information, data and reports provided to us by our client, on behalf of our client, or by third parties (e.g. government agencies) is complete and accurate and on the basis that such other assumptions we have identified (whether or not those assumptions have been identified in this advice) are correct. You must inform us if any of the assumptions are not complete or accurate. We retain ownership of all copyright in this advice. Except where you obtain our prior written consent, this advice may only be used by our client for the purpose for which it has been provided by us. 0500-01 O(rev 1) 9 October 2012 TABLE OF CONTENTS Page 1 INTRODUCTION 1 2 BACKGROUND 2 2.1 CATCHMENT CHARACTERISTICS 2 2.1.1 Pioneer River 2 2.1.2 Fursden Creek 2 2.1.3 Goosepond Creek 2 2.2 PREVIOUS (RECENT) FLOOD STUDIES 4 2.2.1 Pioneer River and Bakers Creek Flood Study 4 2.2.2 Goosepond/ Vines Creek flood Study 4 2.2.3 Mackay Storm Tide Study 5 3 GOOSEPOND CREEK MODEL RECALIBRATION 6 3.1 OVERVIEW 6 3.2 MODEL CHANGES 6 3.3 FEBRUARY 2007 FLOOD CALIBRATION 6 3.4 FEBRUARY 2008 FLOOD CALIBRATION 10 4 DESIGN DISCHARGES AND FLOOD LEVELS 13 4.1 OVERVIEW 13 4.2 PIONEER RIVER DESIGN DISCHARGES 13 4.3 GOOSEPOND CREEK DESIGN DISCHARGES 14 4.3.1 Dominant Cause of flooding in Goosepond Creek 14 4.3.2 Design Discharges 15 4.4 DESIGN FLOOD LEVELS, DEPTHS AND EXTENTS 16 4.5 SUMMARY OF PEAK FLOOD LEVELS AND COMPARISON TO PEAK LEVELS ESTIMATED BY GHD 16 4.6 LEVEE OVERFLOWS 17 5 SUMMARY OF FINDINGS 21 6 REFERENCES 22 i 0500-01 O(rev 1) 9 October 2012 LIST OF TABLES Page Table 3.1 Surveyed and Predicted Peak Water Levels, February 2007 Event 8 Table 3.2 Surveyed and Predicted Peak Water Levels, February 2008 Event 11 Table 4.1 Pioneer River Design Discharges, Pleystowe Mill and Mackay 14 Table 4.2 Goosepond Creek Design Discharges at Goosepond Gauge (Willetts Road) 16 Table 4.3 Predicted Peak Flood Levels at Road Crossings and comparison to GHD peak levels 17 Table 4.4 Predicted Maximum Overflows across Floodplain Levees 20 LIST OF FIGURES Page Figure 2.1 Pioneer River, Fursden Creek and Goosepond Creek Catchments 3 Figure 3.1 Recorded and Predicted Water Levels and Predicted Discharges, Goosepond Ck at Gooseponds (Willetts Road) Gauge (GS125915), February 2007 Event 7 Figure 3.2 Predicted Flood Depths, Levels and Extent, 2 February 2007 9 Figure 3.3 Recorded and Predicted Water Levels and Predicted Discharges, Goosepond Ck at Gooseponds (Willetts Road) Gauge (GS125915), February 2008 Event 10 Figure 3.4 Predicted Flood Depths, Levels and Extent, 15 February 2008 12 Figure 4.1 Pleystowe Mill Design Discharges 14 Figure 4.2 Goosepond Creek at Goosepond (Willetts Rd) Gauge Discharge Hydrograph, 100 year ARI 12hr and 24hr events 15 Figure 4.3 10 Year ARI Flood Depths and Extent, Pioneer River and Bakers Creek 18 Figure 4.4 100 Year ARI Flood Depth and Extent, Pioneer River and Bakers Creek 19 ii 0500-01 O(rev 1) 9 October 2012 1 INTRODUCTION Mackay Regional Council (MRC) recently completed flood studies of the Pioneer River (WRM, 2011) and Goosepond Creek (GHD, 2012). These studies estimated design flood levels along these waterways to assist with setting planning controls for urban development. Both of these studies found that there was a significant interaction of flood flows between Goosepond Creek and the Pioneer River. However, the Goosepond Creek study did not include the overflows from the Pioneer River and the Pioneer River study did not investigate the impact of local storms in the Goosepond Creek catchment in combination with Pioneer River flows. This report integrates the two studies to determine design flood levels along Goosepond Creek. This report is structured as follows: Section 2 describes the catchments of interest and summarises the findings of the previous flood studies; Section 3 outlines the changes made to the Pioneer River model to integrate Goosepond Creek and presents the results of the Goosepond Creek model calibration; Section 4 presents the updated design flood levels and discharges along the Pioneer River and Goosepond Creek and describes the interaction of flows between the two waterways; Section 5 summarises the findings of the study; and Section 6 is a list of references. 1 0500-01 O(rev 1) 9 October 2012 2 BACKGROUND 2.1 CATCHMENT CHARACTERISTICS Figure 2.1 shows the location of the Pioneer River, Fursden Creek and Goosepond Creek catchments. Brief descriptions of the catchments are given below. 2.1.1 Pioneer River The Pioneer River catchment extends from the Connors Range to the west to the City of Mackay to the east. It includes the major tributaries of Cattle Creek, Teemburra Creek, Blacks Creek, Stockyard Creek, Macgregor Creek, Fursden Creek, Janes Creek and Gooseponds Creek. The catchment is bordered by the Leila Creek and Murray Creek catchments to the north, the Bowen River catchment to the west and Sandy Creek, Bakers Creek and the Isaac River catchments to the south. The total catchment area of the Pioneer River (excluding the Bakers Creek catchment) is approximately 1,560 km2. 2.1.2 Fursden Creek Fursden Creek commences near Fairview on the Bruce Highway and drains in a southerly direction mostly along constructed channels through cane fields. It then turns eastward to drain parallel to the Pioneer River before entering it just upstream of the Ron Camm Bridge (Bruce Highway). The lower sections of the creek are backwater affected by both ocean tides and Pioneer River flows. For floods greater than the 5 year ARI event, the Pioneer River overflows into Fursden Creek. During large floods, the Fursden Creek channel carries a significant portion of the Pioneer River flow. The catchment area of Fursden Creek is 24.8 km2. 2.1.3 Goosepond Creek Janes Creek, Goosepond Creek and Vines Creek drain through the northern and eastern suburbs of Mackay. Janes Creek originates near Farleigh and Richmond (north-west of the Mackay CBD) and flows into Goosepond Creek downstream of the Bruce Highway. Goosepond Creek then drains into Vines Creek upstream of Harbour Road. Vines Creek originates near Beaconsfield and drains into the Pioneer River downstream of Harbour Road in an area known as the Bassett Basin. The combined catchment area of these 3 streams is approximately 35 km2. 2 0500-01 O(rev 1) 9 October 2012 BRUCEBRUCE HWYHWY FursdenFursden GoosepondsGooseponds CreekCreek CreekCreek NORTHNORTH MACKAYMACKAY CATTLECATTLECATTLE CREEK CREEKCREEK FINCHFINCH HAHATTONTTON PIONEERPIONEER RIVRIV ER ER MARIANMARIAN MACKAYMACKAY MIRANIMIRANI WALKERSTONWALKERSTON BAKERSBAKERS CREEKCREEK BAKERSBAKERS CREEKCREEK PEAKPEAKPEAK DOWNS DOWNSDOWNS HWYHWYHWY BRUCEBRUCEBRUCE HWYHWYHWY LEGEND Main Road Drainage Line Water Body Park/State Forest Built Up Area SARINASARINAFursden Creek Catchment Goosepond Creek Catchment 0510 Pioneer River Catchment kilometres Figure 2.1 Pioneer River, Fursden Creek and Goosepond Creek Catchments 3 0500-01 O(rev 1) 9 October 2012 2.2 PREVIOUS (RECENT) FLOOD STUDIES 2.2.1 Pioneer River and Bakers Creek Flood Study WRM completed a flood study of the Pioneer River and Bakers Creek in 2011 for MRC. An URBS rainfall-runoff-routing model of the Pioneer River catchment was developed to estimate design discharges. The model was calibrated to six historical flood events (1958, 1970, 1990, 2000, 2007 and 2008) and then validated against annual series flood frequency analyses at five stream gauges throughout the catchment. Design flood levels were estimated using a TUFLOW two-dimensional hydrodynamic model that extended from Mirani Weir to the Coral Sea. The model was calibrated to recorded water levels for four historical flood events (1958, 1970, 2007 and 2008). The main river channel upstream of the Dumbleton Weir was modelled in the one-dimensional domain and the downstream river and overbank areas were modelled within the two-dimensional domain using a 20m grid. For all events, it was assumed that the flood event coincided with the highest astronomical tide (HAT) level of 3.64m AHD. Full details of the development and calibration of the models are given in the flood study report (WRM, 2011). The following comments are provided on the Pioneer River Study with respect to flooding along Goosepond Creek: Design rainfalls for the Goosepond Creek catchment were based on Pioneer River catchment design rainfalls. For a 24 hour duration storm, the design rainfall depth in the Goosepond Creek catchment is some 8% higher than in the Pioneer River catchment; Goosepond Creek catchment inflows were based on only four URBS sub areas. Surveyed ground levels along Goosepond Creek were found to be up to 1m lower than the ground levels adopted in the Pioneer River study, which were obtained from the Lidar survey provided by MRC. Goosepond Creek channel capacities and Manning’s ‘n’ values were not calibrated using all of the available data. 2.2.2 Goosepond/ Vines Creek flood Study GHD Pty Ltd was commissioned by MRC to undertate a flood study for Goosepond Creek, Janes Creek, Vines Creek and the Port Access Corridor in the North Mackay area. A RAFTS rainfall- runoff-routing model was used to estimate design discharges and a MIKEFLOOD hydrodynamic model was used to estimate design flood levels.