20180213093255001.0TRUEThe purpose of this report is to present the approach and results to update guidelines for the Otago Region’s reasonable daily and seasonal irrigation water requirements. This project was completed by Aqualinc Research Limited (Aqualinc) in consultation with ORC and with inputs from stakeholders. The project was undertaken in the following stages: Stage 1: Review of previous ORC irrigation guidelines (Aqualinc 2006) and the scoping of work required through stakeholder consultation. Stage 2: Development of the final irrigation guidelines as presented in this report using water balance computer modelling for a range of climatic, soil, crop and irrigation management parameters. Stage 1 aimed at identifying the shortcomings and concerns of the previous irrigation guidelines through consultation with irrigation water users and industry representatives. The consultation process laid the foundations to develop the scope for the Stage 2 of the project. In addition, the stakeholder consultation was also valuable in gathering parameters necessary for water balance computer modelling. Stage 2 was dedicated to developing reasonable irrigation requirement values for crops and pasture. Aqualinc’s water balance computer model, Irricalc was used for crops, and CSIRO’s AusFarm model was used for pasture. Both models use the principles developed by Food and Agriculture Organization (FAO) of the United Nations for daily soil moisture water balance modelling (Allen et al., 1998). Both models used either NIWA’s virtual climate station (VCS) climate data, or climate station data directly. VCS data is available at a 5 km by 5 km grid across the region. Aqualinc considers that data on a 5 x 5 km grid provides reasonable guidance of daily and mean annual rainfall for a given location. The crops that are modelled include pasture, grapes, stonefruit (represented by apricots and cherries) and market garden vegetables (represented by a crop rotation of potatoes and cabbages). The water requirement modelling was carried out for five soil plant available water (PAW) classes that cover the potential range of PAW values within the Otago Region. The model outputs, therefore, can be used for any PAW in the Otago region without need to re-run the model if future high resolution soil surveys determine different soil water characteristics than what is available presently. The water balance modelling has been carried out for 42 irrigation seasons (1972 to 2014). Peak daily demand (mm/day), peak monthly demand (mm/month) and mean, 80 percentile, 90 percentile and maximum annual demand (mm/year) for a combination of climate (location), soil, crop and irrigation systems are provided. The irrigation guidelines for reasonable water use in the Otago Region have been developed using internationally accepted water balance computer modelling. The computer model have been field verified in a wide range of soil and climate conditions in New Zealand. On that basis, the guideline values presented in this document and associated electronic files for different soil-crop-climate and irrigation management combinations are appropriate for determining reasonable water allocation limits for irrigation in the Otago Region.MARRainfallAqualincIrrigationMean Annual RainfallOtagoSpatial Data In Support Of The Irrigation Report "Guidelines For Reasonable Irrigation Water Requirements In The Otago Region" C15000 2017/07/24Aqualinc Research LtdInformation on this feature layer may not be used for the purposes of any legal disputes. The user should independently verify the accuracy of any information before taking any action in reliance upon it.