Surface-Groundwater Interaction Model of the Murrumbidgee Irrigation Area (Development of the Hydrogeological Databases)
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Surface-Groundwater Interaction Model of the Murrumbidgee Irrigation Area (Development of the Hydrogeological Databases) By S. Khan, L. Best and B. Wang CSIRO Land and Water, Griffith NSW Technical Report 36/02, August 2002 CSIRO LAND and WATER Copyright © 2002 CSIRO Land and Water. To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO Land and Water. Important Disclaimer To the extent permitted by law, CSIRO Land and Water (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. ISSN 1446-6163 Surface-Groundwater Interaction Model of the Murrumbidgee Irrigation Area (Development of the Hydrogeological Databases) By S. Khan, L. Best and B. Wang CSIRO Land and Water, Griffith NSW Technical Report 36/02, August 2002 Acknowledgements The authors wish to acknowldge Mr Ary van der Lely, Mr Scott Lawson and Ms Liz Webb of DLWC, Leeton and Ms Lillian Parker and Mr Rob Kelly of the Murrumbidgee Irrigation Limited for providing the necessary data sets required for the development of this model. We are also thankful to Kevin Day of DLWC Paramatta for providing structural contour data of the aquifers. Collection of river and channel network cross-sections data by Ms Nicola King and Mr Jason Carroll is acknowledged. Review comments by Mr Ary van der Lely and Dr Liz Humphreys are appreciated. The funding support of the CRC for the Sustainable Rice Production is acknowledged which made this work possible. Abstract This report describes the development of a surface-groundwater interaction model for the Murrumbidgee Irrigation Area. The US geological survey model MODFLOW coupled with the MT3D solute transport simulator under a PMWIN environment was used as the modeling framework. The spatial domain represented in the model consists of four layers each of 106 rows and 113 columns (750m x 750m cell size). A stress period length of 30-days was used to enable simulation of irrigation and non-irrigation seasons with a computational time step of one day. Initially the model parameters have been specified for the 1995 to 2000 period for calibration purposes. Extensive datasets on the aquifer lithology (structural contours, borelogs, aquifer properties), piezometric levels, groundwater salinity, aquifer abstractions, channel network, Murrumbidgee River and rice area locations have been collected and collated in ArcView GIS format. This work has provided an opportunity to consolidate a larger number of scattered databases into various formats for the MIA and in a form which can be readily used to carry out a range of environmental studies. Several customised programs have been written for the manipulation of the difficult data sets to incorporate them into MODFLOW-MT3D format for the 1995-2000 period. A working surface-groundwater interaction model of the MIA is now available. This model is currently being calibrated and would be used to simulate Land and Water Management scenarios and to quantifiy climatic and management impacts on shallow watertables and soil salinity. Table of Contents 1 INTRODUCTION TO THE STUDY AREA .......................................................................................... 12 1.1 GEOGRAPHICAL LOCATION ............................................................................................................ 12 1.2 CLIMATE ........................................................................................................................................ 13 1.3 GEOLOGY OF THE MURRUMBIDGEE IRRIGATION AREA .................................................................. 15 1.4 SOILS.............................................................................................................................................. 17 1.5 IRRIGATION HISTORY ..................................................................................................................... 18 1.6 LANDUSE........................................................................................................................................ 18 1.7 NUMBER OF FARMS ........................................................................................................................ 21 1.8 WATER-LOGGING SOIL AND SALINISATION .................................................................................... 21 1.9 LAND & WATER MANAGEMENT PLAN ........................................................................................... 23 1.9.1 The LWMP options to address above issues include: ....................................................... 24 1.9.2 MIA LWMP targets include: ............................................................................................. 24 1.9.3 Actions to achieve ............................................................................................................. 24 1.10 PREVIOUS GROUNDWATER STUDIES............................................................................................... 25 2 OBJECTIVES OF MODELLING STUDY............................................................................................. 27 3 CONCEPTUAL MODEL OF THE MURRUMBIDGEE IRRIGATION AREA................................ 28 4 DATA REQUIREMENTS........................................................................................................................ 32 5 PROCESSED DATABASES FOR THE GROUNDWATER MODEL................................................ 33 5.1 DATA FORMATS ............................................................................................................................. 33 5.1.1 Drill Logs.......................................................................................................................... 33 5.1.2 Groundwater Elevations ................................................................................................... 33 5.1.3 Groundwater Abstractions Data....................................................................................... 34 5.2 SPATIAL DISCRETISATION OF AQUIFER LAYERS............................................................................. 35 5.3 MANIPULATION OF DRILL LOGS..................................................................................................... 36 5.4 PARAMETERS FOR DERIVING HYDRAULIC PROPERTIES.................................................................... 37 5.5 SOIL TYPES..................................................................................................................................... 37 5.6 DETERMINATION OF KS................................................................................................................... 38 5.7 DETERMINATION OF SS ................................................................................................................... 39 5.8 DETERMINATION OF SY ................................................................................................................... 40 5.9 GROUNDWATER ELEVATIONS......................................................................................................... 41 5.10 GROUNDWATER ABSTRACTIONS .................................................................................................... 42 5.11 CHANNEL NETWORK ...................................................................................................................... 42 5.12 SPATIAL DISTRIBUTION OF GROUNDWATER SALINITY ................................................................... 47 5.13 INTERPOLATION.............................................................................................................................. 47 4 Table of Contents 6 DETAILS OF THE MURRUMBIDGEE GROUNDWATER MODEL .............................................. 52 6.1 MODEL PROPERTIES ....................................................................................................................... 52 6.2 ZONING .......................................................................................................................................... 54 6.3 GRIDDING DATA............................................................................................................................. 54 6.4 VERTICAL AND HORIZONTAL HYDRAULIC CONDUCTIVITY ............................................................ 54 6.5 FORMATIONS .................................................................................................................................. 54 6.6 GROUNDWATER ABSTRACTIONS .................................................................................................... 55 6.7 CHANNEL NETWORK ...................................................................................................................... 55 7 SUMMARY AND FURTHER STUDIES................................................................................................ 56 8 REFERENCES .......................................................................................................................................... 57 9 APPENDIX A - STRUCTURE CONTOURS ......................................................................................... 60 10 APPENDIX B - HYDRAULIC CONDUCTIVITY ...............................................................................