DPIW – SURFACE WATER MODELS ARTHUR, RAPID AND HELLYER RIVER CATCHMENTS Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 DOCUMENT INFORMATION JOB/PROJECT TITLE Tascatch Variation 2 -Surface Water Models CLIENT ORGANISATION Department of Primary Industries and Water CLIENT CONTACT Bryce Graham DOCUMENT ID NUMBER WR 2008/007 JOB/PROJECT MANAGER Mark Willis JOB/PROJECT NUMBER E202869/P205357 Document History and Status Revision Prepared Reviewed Approved Date Revision by by by approved type 1.0 James Mark Willis Crispin May 2008 FINAL Bennett Smythe Current Document Approval PREPARED BY James Bennett Water Resources Mngt Sign Date REVIEWED BY Mark Willis Water Resources Mngt Sign Date APPROVED FOR Crispin Smythe SUBMISSION Water Resources Mngt Sign Date Current Document Distribution List Organisation Date Issued To DPIW May 2008 Bryce Graham The concepts and information contained in this document are the property of Hydro Tasmania. This document may only be used for the purposes of assessing our offer of services and for inclusion in documentation for the engagement of Hydro Tasmania. Use or copying of this document in whole or in part for any other purpose without the written permission of Hydro Tasmania constitutes an infringement of copyright. i Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 EXECUTIVE SUMMARY This report is part of a series of reports which present the methodologies and results from the development and calibration of surface water hydrological models for 25 catchments (Tascatch – Variation 2) under both current and natural flow conditions. This report describes the results of the hydrological model developed for the Arthur, Rapid and Hellyer River catchments. A model was developed for the Arthur, Rapid and Hellyer River catchments that facilitates the modelling of flow data for three scenarios: • Scenario 1 – No entitlements (Natural Flow); • Scenario 2 – with Entitlements (with water entitlements extracted); • Scenario 3 - Environmental Flows and Entitlements (Water entitlements extracted, however low priority entitlements are limited by an environmental flow threshold). The results from the scenario modeling allow the calculation of indices of hydrological disturbance. These indices include: • Index of Mean Annual Flow • Index of Flow Duration Curve Difference • Index of Seasonal Amplitude • Index of Seasonal Periodicity • Hydrological Disturbance Index The indices were calculated using the formulas stated in the Natural Resource Management (NRM) Monitoring and Evaluation Framework developed by SKM for the Murray-Darling Basin (MDBC 08/04). A user interface is also provided that allows the user to run the model under varying catchment demand scenarios. This allows the user to add further extractions to catchments and see what effect these additional extractions have on the available water in the catchment of concern. The interface provides sub-catchment summary of flow statistics, duration curves, hydrological indices and water entitlements data. For information on the use of the user interface refer to the Operating Manual for the NAP Region Hydrological Models (Hydro Tasmania 2004). ii Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 CONTENTS EXECUTIVE SUMMARY ii 1. INTRODUCTION 1 2. CATCHMENT CHARACTERISTICS 2 3. DATA COMPILATION 5 3.1 Climate data (Rainfall & Evaporation) 5 3.2 Advantages of using climate DRILL data 5 3.3 Transposition of climate DRILL data to local catchment 6 3.4 Comparison of Data Drill rainfall and site gauges 8 3.5 Streamflow data 10 3.6 Irrigation and water usage 10 3.6.1 Estimation of unlicensed (small) farm dams 18 3.7 Environmental flows 19 4. MODEL DEVELOPMENT 22 4.1 Sub-catchment delineation 22 4.2 Hydstra Model 22 4.2.1 Talbots Lagoon 25 4.2.2 Inter-Basin Transfer: Talbots Lagoon 26 4.3 AWBM Model 28 4.3.1 Channel Routing 30 4.4 Model Calibration 32 4.4.1 Factors affecting the reliability of the model calibration. 44 4.4.2 Model Accuracy - Model Fit Statistics 45 4.4.3 Model accuracy across the catchment 49 5. MODEL RESULTS 54 5.1.1 Indices of hydrological disturbance 55 6. FLOOD FREQUENCY ANALYSIS 58 7. REFERENCES 60 7.1 Personal Communications 60 8. GLOSSARY 61 APPENDIX A 63 iii Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 LIST OF FIGURES Figure 2-1 Sub-catchment boundaries 4 Figure 3-1 Climate Drill Site Locations 7 Figure 3-2 Rainfall and Data Drill Comparisons 9 Figure 3-3 WIMS Water Allocations 17 Figure 4-1 Hydstra Model Schematic 24 Figure 4-2 Two Tap Australian Water Balance Model Schematic 30 Figure 4-3 Monthly Variation of CapAve Parameter 36 Figure 4-4 Daily time series comparison (ML/d) – upper Hellyer River - Good fit.37 Figure 4-5 Daily time series comparison (ML/d) – upper Hellyer River– Good fit.38 Figure 4-6 Daily time series comparison (ML/d) – upper Hellyer River– Good fit.38 Figure 4-7 Daily time series comparison (ML/d) –Arthur River - Good fit. 39 Figure 4-8 Daily time series comparison (ML/d) – Arthur River– Good fit. 39 Figure 4-9 Daily time series comparison (ML/d) – Arthur River– Good fit. 40 Figure 4-10 Monthly time series comparison – volume (ML) Hellyer River at Guildford Junction 40 Figure 4-11 Monthly time series comparison – volume (ML) Arthur River below Rapid River 41 Figure 4-12 Long term average monthly, seasonal and annual comparison plot for Hellyer River at Guildford Junction 41 Figure 4-13 Long term average monthly, seasonal and annual comparison plot for Arthur River below Rapid River 42 Figure 4-14 Hellyer River at Guildford Junction Duration Curve – Daily flow percentage difference 47 Figure 4-15 Hellyer River at Guildford Junction Duration Curve – Monthly volume percentage difference 48 Figure 4-16 Arthur River below Rapid River Duration Curve – Daily flow percentage difference 48 Figure 4-17 Arthur River below Rapid River Duration Curve – Monthly volume percentage difference 49 Figure 4-18 Time Series of Monthly Volumes- SC1_k 51 Figure 4-19 Time Series of Monthly Volumes- SC1_u 51 Figure 4-20 Time Series of Monthly Volumes- SC15_d 52 Figure 4-21 Time Series of Monthly Volumes- SC15_h 53 Figure 5-1 Daily Duration Curve – Arthur River below Rapid River 54 Figure 5-2 Daily Duration Curve – Hellyer River at Guildford Junction 55 Figure 6-1 Modelled and Observed Flood Frequency Plot – Hellyer at Guildford Junction 59 Figure 6-2 Modelled and Observed Flood Frequency Plot – Arthur River below Rapid 59 Figure A-1 Forth catchment – monthly volumes at secondary site. 65 Figure A-2 George catchment – monthly volumes at secondary site. 65 Figure A-3 Leven catchment – monthly volumes at secondary site. 66 Figure A-4 Swan catchment – monthly volumes at secondary site. 66 Figure A-5 Montagu catchment – monthly volumes at secondary site. 67 iv Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 LIST OF TABLES Table 3.1 Data Drill Site Locations 6 Table 3.2 Potential calibration sites 10 Table 3.3 Assumed Surety of Unassigned Records 11 Table 3.4 Sub Catchment High and Low Priority Entitlements 12 Table 3.5 Average capacity for dams less than 20 ML by Neal et al (2002) 19 Table 3.6 Environmental Flows 20 Table 4.1 Monthly Interbasin Transfers from Talbots Lagoon (ML/day) 27 Table 4.2 Boughton & Chiew, AWBM surface storage parameters 28 Table 4.3 Hydstra/TSM Modelling Parameter Bounds 31 Table 4.4 Adopted Calibration Parameters for Hellyer River above Hellyer gauging site 35 Table 4.5 Adopted Calibration Parameters Arthur River, Rapid River, Frankland River, and Hellyer River below Hellyer gauging site 36 Table 4.6 Long term average monthly, seasonal and annual comparisons 43 Table 4.7 Model Fit Statistics 46 2 Table 4.8 R Fit Description 46 Table 5.1 Hydrological Disturbance Indices 56 Table A-1 Model performance at secondary sites 68 v Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 1. INTRODUCTION This report forms part of a larger project commissioned by the Department of Primary Industries and Water (DPIW) to provide hydrological models for 25 regional catchments (Tascatch – Variation 2). The main objectives for the individual catchments are: • To compile relevant data required for the development and calibration of the hydrological model (Australian Water Balance Model, AWBM) for the Arthur, Rapid and Hellyer River catchments; • To source over 100 years of daily time-step rainfall and streamflow data for input to the hydrologic model; • To develop and calibrate each hydrologic model, to allow running of the model under varying catchment demand scenarios; • To develop a User Interface for running the model under these various catchment demand scenarios; • Prepare a report summarising the methodology adopted, assumptions made, results of calibration and validation and description relating to the use of the developed hydrologic model and associated software. 1 Arthur, Rapid and Hellyer Rivers Surface Water Model Hydro Tasmania Version No: FINAL 1.0 2. CATCHMENT CHARACTERISTICS The Arthur River drains a 2500 km 2 catchment in north-western Tasmania, flowing west from the mountainous centre of Tasmania into the Southern Ocean. The Rapid and Hellyer Rivers are major tributaries of the Arthur River, with catchment areas of 301 km 2 and 332 km 2, respectively. The other major tributary of the Arthur is the Frankland River (555 km 2), which flows into the Arthur near the west coast. The Arthur catchment is remote from major human settlements, and as a result has few flow gauging sites compared to other Tasmanian streams with similarly large catchments. The headwaters of the Arthur are fed by runoff from highland plains at 1000 m ASL.