Update of Flow Statistics for Tributaries of the Upper Waitaki River
Total Page:16
File Type:pdf, Size:1020Kb
Update of flow statistics for tributaries of the Upper Waitaki River Report No. R13/66 ISBN 978-1-927257-68-5 (print) ISBN 978-1-927257-69-2 (web) S Gabites June 2013 Report No. R13/66 ISBN 978-1-927257-68-5 (print) ISBN 978-1-927257-69-2 (web) PO Box 345 Christchurch 8140 Phone (03) 365 3828 Fax (03) 365 3194 75 Church Street PO Box 550 Timaru 7940 Phone (03) 687 7800 Fax (03) 687 7808 Website: www.ecan.govt.nz Customer Services Phone 0800 324 636 Update of flow statistics for tributaries of the Upper Waitaki River Community Summary This summary is for non-technical members of the community and based on the information found in this report. The community summary should be regarded as summarised technical material. The purpose The purpose of this investigation was to add to the information we had on river flow for the Upper Waitaki River tributaries. We used this to update our understanding of the river network/system and ensure we have good robust knowledge of how much water there is, where water is coming from and where it is going. What we did Over the years 2003 and 2004 Environment Canterbury hydrology field staff measured the surface water flows at least eight times is around 140 rivers and streams in the Upper Waitaki. This information was used to create a basic understanding of river flows. It also showed where gaps in our knowledge were. To fill these gaps our hydrology field staff measured water flows at 54 locations in the Upper Waitaki over the years 2007 and 2008. Combining the information from the two investigations helps us to further complete the picture and fit the recent information into the existing knowledge. How are we using the information? Where to from here? We now understand better how much water is where. We will be able to give more robust estimates of flow statistics to better represent river and stream flow and build a numerical model representing the interactions between river/stream flow, groundwater and water quality in the Upper Waitaki. In the future Environment Canterbury may then use this information to assist in making decisions on water allocation, minimum flows, and nutrient load limits in streams and rivers in this region. Environment Canterbury Technical Report i Update of flow statistics for tributaries of the Upper Waitaki River Executive Summary Between 2003-2004, an extensive field investigation throughout the Waitaki catchment was carried out with the purpose of gaining knowledge of flows at around 140 sites (Gabites and Horrell, 2005). Some of these sites had been measured in the past while for many there was no flow information. The information gained by this survey was invaluable. Gabites and Horrell (2005) estimated seven-day mean annual low flow (MALF(7D)), and mean flow, and made recommendations for further field work to improve areas of uncertainty. Another field survey was carried out in 2007-2008, involving 54 sites focusing on the central Mackenzie Basin rivers and streams, including Grays River, Irishman Creek, Mary Burn, Twizel River, Quail Burn, Wairepo Creek and some selected tributaries of these streams. This report gives details of updated flow statistics for these streams. However, with any work of this kind there are complications caused by some sites lacking measurements at higher or low flows, which has resulted in some streams’ estimates not being available until further gaugings are completed. This report also makes recommendations for further field work at selected sites throughout the catchment, including all minimum flow sites, and water quality monitoring sites. A greater number of field measurements, together with a greater number of consented takes being metered, should give us greater confidence in our flow knowledge of the catchment’s tributaries. The results from this report will assist in developing an integrated surface water, groundwater and water quality model of the catchment, which will then lead into limit setting by way of a sub- regional plan for the Waitaki Catchment. The outcomes of the model and any subsequent analysis and information are likely to feed into the sub-regional flow plan review. ii Environment Canterbury Technical Report Update of flow statistics for tributaries of the Upper Waitaki River Table of Contents Community Summary ................................................................................................ i Executive Summary .................................................................................................. ii Glossary ............................................................................................................... v 1 Introduction ..................................................................................................... 1 1.1 Background ..................................................................................................................... 1 1.2 The Waitaki Catchment Water Allocation Plan (2005) ................................................... 1 1.3 Canterbury Water Management Strategy (CWMS) ........................................................ 2 1.4 Recent consent history in the catchment ........................................................................ 2 2 River flow measurements ............................................................................... 3 2.1 Recorder sites ................................................................................................................. 4 2.1.1 Twizel River at Lake Poaka ............................................................................... 4 2.1.2 Quail Burn at Quail Burn Road .......................................................................... 5 2.2 Flow gaugings ................................................................................................................. 6 2.3 Naturalising method ........................................................................................................ 6 3 Results ............................................................................................................. 7 3.1 Fork Stream, Mary Burn, Irishman Creek and tributaries ............................................... 7 3.2 Grays River, Stony River and tributaries ......................................................................10 3.3 Twizel River and tributaries, plus some small streams in the central area...................12 3.4 Quail Burn, Hen Burn, and Wairepo Creek area ..........................................................15 4 Current minimum flow sites ......................................................................... 17 5 Recommendations for future work .............................................................. 19 6 Acknowledgements ...................................................................................... 22 7 References ..................................................................................................... 22 Appendix 1: Forks/Mary Burn/Irishman Regressions .......................................... 25 Appendix 2: Grays/Stony Regressions................................................................. 26 Appendix 3: Twizel and small streams in the central area regressions ............ 29 Appendix 4: Quail Burn and Wairepo area regressions ....................................... 32 Environment Canterbury Technical Report iii Update of flow statistics for tributaries of the Upper Waitaki River List of Figures Figure 2-1: Investigation area, including all measurement sites.......................................................... 3 Figure 2-2: Twizel River at Lake Poaka gaugings vs Ahuriri River at South Diadem daily mean discharges ......................................................................................................................... 5 Figure 2-3: Quail Burn at Quail Burn Road gaugings vs Omarama Stream at above Tara Hills daily mean discharges ....................................................................................................... 6 Figure 3-1: Irishman Creek flow changes above Tekapo River confluence ........................................ 7 Figure 3-2: Mary Burn flow changes above Tekapo River confluence ................................................ 8 Figure 3-3: Hydrographs for Grays at Days Bridge and Mary Burn at SH8 ......................................10 Figure 3-4: Twizel River flow changes above Ohau River Confluence .............................................13 Figure 3-5: Quail Burn flow changes above Ahuriri River Confluence ..............................................15 Figure 5-1: Gauging run 2013-2014 ..................................................................................................21 List of Tables Table 2-1: List of recorder sites used for the basis of this investigation ............................................. 4 Table 3-1: Flow statistics for Forks Stream, Mary Burn, Irishman Creek and tributaries ................... 9 Table 3-2: Flow statistics for Grays River, Stony River and tributaries ............................................11 Table 3-3: Flow statistics for the Twizel and tributaries and some others in the central area ..........14 Table 3-4: Flow statistics for the Quail Burn and tributaries, and Wairepo area ..............................16 Table 4-1: Calculated Q5 flows for existing and Plan minimum flow sites .......................................18 Table 5-1: Gauging run for the Waitaki catchment for 2013-2014 ...................................................20 iv Environment Canterbury Technical Report