Outline Whangamarino Wetland Hydrology Study > Background and purpose > Wetland hydrological function > Model development Blair Thornburrow1 & Michael Lake2 1Sinclair Knight Merz, 2Department of Conservation Background Firth of Thames Overall Purpose of Project To Auckland (& Whangarei) > Whangamarino > Hydrological function o Arawai Käkäriki wetland > Hydrological management restoration programme o Ramsar site > Influence on ecology o Impacted hydrology > Informed decision making for wetland managers > Water regime = key driver of wetland ecology To Hamilton Hydrological Function Control structure > Natural + diverted inflows (Waikato R.) > Storage in wetland and lake Ropeway 587 km2 catchment Falls Rd > Subject to modifications o Waikato-Waipa flood protection works Waikare o Waikato River sand extraction o Flow diversions o DOC/Fish & Game weir at outlet 210 km2 catchment > Waikare outlet gate - Spills from Lake Waikare into Pungarehu Stream and wetland > Rock weir Regulates outflow/ water level from wetland > Te Onetea culvert - Spills from Waikato River to Lake Waikare 1 Water Level Data (long term) Water Level Data (2008) 7 Water level (mAM MSL) 6 Control Structure (d/s) Waikare Ropeway Falls Rd Falls Rd Ropeway Control Structure (u/s) Waikare 6 Water level (mAM MSL) 7 5 4 3 2 Waikare Falls Rd Ropeway Control Structure (u/s) 5 4 3 2 1 1 01/01/08 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 10/04/08 19/07/08 27/10/08 04/02/09 Water Level Data (transect) 1 2 5 3 1 2 Water leve el (mAMSL) 4 3 4 5 Water Balance Model Inputs > Preliminary model framework developed > Catchment runoff o Calibrated rainfall runoff models o Evaluate methodology o Identify data gaps > GoldSim modelling environment > Why? Hydrological cause & effect > Diverted inflows 2 Water Balance Model Operation Preliminary Outputs > Stage hydrographs Preliminary Outputs Preliminary Outputs > Water balance > Water balance (average) 2005 Preliminary Outputs > Inundation o Spatial extent o Frequency o Duration > Based on arbitrary elevation data o LIDAR would be ideal Whangamarino IN m3/s GL/yr % Waikare outflow 7.86 248 42% Rain on wetland surface 0.50 16 3% Runoff from catchment 10.32 326 55% Total IN 18.68 589 100% Whangamarino OUT m3/s GL/yr % Evaporation 0.25 8 1% Outflow at weir 18.41 581 99% Total OUT 18.67 589 100% Data gaps > Depth/volume relationships o Additional elevation data (e.g. LIDAR) > Weir rating curve o Gauging data > Waikare outlet gate o Gauging data o Operation Kopuatai LIDAR data 3 Summary Conclusions > Water regime key driver of ecology at Whangamarino > Simulation approach → useful tool o Need to know more > Water balance model framework developed o Preliminary results promising o Further data required to enable detailed > Ability to be coupled with ecological modelling > Testing off scenarios, options, cause & effect > Will inform water management decision making for ecological outcomes modelling 4