Climate Surfaces for the Okanagan Basin Water Supply Demand Project

The diverse terrain of the Okanagan Basin has a strong localizing influence on climate. Model development for water supply and demand requires climate data inputs that reflect this complexity. The Okanagan Climate Data Model has been developed to provide climate information at a suitable scale for modelling climate dependent processes. Using GIS interpolation methodology and all available climate data from a number of sources, basin-wide 500m x 500m gridded surfaces for daily minimum, maximum temperatures and precipitation have been generated for the period 1960 to 2000. Future daily climate data, up to the year 2100, have also been generated using output from six Global Climate Models (GCM) and three SRES scenarios reflecting high and low greenhouse gas emissions. GCM output has been downscaled to climate grid cells using a combined synoptic map typing and weather generator approach. The Okanagan Climate Data Model has been used to drive the Okanagan Irrigation Water Demand Model, which provides calculations of Penman Monteith reference and a range of agro-climatic indices for each climate grid cell in addition to crop and terrain based irrigation water demand.