Water use characteristics of irrigated crops in the southern MDB: weather-based irrigation scheduling D. Whitfield, M. O’Connell, L. McClymont A. McAllister, M. Abuzar, K. Sheffield Satellite-based Water Use Applications: • Field/crop scale irrigation scheduling • Farm/region/industry scale water use benchmarking, planning, reporting Irrigation Water Use: SUPPLY = CROP DEMAND (± LF) SUPPLY: irrigation, rainfall CROP DEMAND: CWR = Kc ETo crop type, weather (ETo) Kc : crop type, condition/status CROP DEMAND: CWR = Kc ETo long-running questions associated with both Kc and ETo in Australia: Highly structured, discontinuous tree/vine crops (stone/pome fruits, vine, nut and citrus) are major crops in Riverland, Sunraysia, GMID: ETo: the most appropriate measure of reference crop evapotranspiration? Allen RG, Pereira LS, Raes D & Smith M (1998): Crop evapotranspiration - Guidelines for computing crop water requirements FAO Irrigation and drainage paper 56 Allen RG, Walter, IA, Elliott RL, Howell, TA, Itenfisu D; Jensen, ME & Snyder RL (2005): The ASCE Standardized Reference Evapotranspiration Equation Meyer, WS (1999): Standard Reference Evapotranspiration calculation for inland SE Australia. CSIRO Land and Water Tech Report 35/98 DEPI/NWI Water Use Measurement, Monitoring, Reporting project: applied satellite-based SEBAL-METRIC measures to major crops grown in major irrigation districts of MDB in period, 2007-2010. Aims: • Characterise water use of irrigated crops in MDB • implications for improved irrigation water management, reporting, planning. Methods: Kc approach (FAO56, ASCE-EWRI): • Quantitative. • Scalable, with consistent application of supply/demand principles across the range of areal and time scales relevant to irrigation water management and planning at field-farm/regional-industry scales. Methods (cont.): • METRIC developed by Allen et al (from SEBAL) • water use characteristics of all major crops in major irrigation areas of southern MDB • Compare Australian crops with existing Allen Idaho data: Tasumi et al (2005) related METRIC ET to vegetation cover (NDVI) in Idaho crops GV dairy pasture ET/ETr GV dairy pasture ET/ETo 3 classes crop water use in southern MDB: Stone/pome, citrus, grape, nut • Strong increase in ET/ETr with increase in NDVI • ETmax = ETr Perennial dairy pastures • Strong increase in ET/ETr with increase in NDVI • ETmax = ETo Rice • ET/ETr = 1 pre-emergence • ET/ETr < 1 post-emergence • ETmax = ETr in full-grown crop Class 1 well-watered crops (ET/ETr > irr refill line): Kc = ET/ETr Kc depends on canopy cover (NDVI): Project: crop-specific relationships between crop water use (ET, CWR), weather(ETr) and vegetation cover (NDVI). Soil water balance – irrigation scheduling Can therefore provide satellite-based fieldscale irrigation scheduling advice/services based on weather data, satellite ET, and vegetation data (NDVI) VicDEPI FarmWeb Irrigation scheduling NDVI + weather Satellite-based irrigation schedule Soil water balance – irrigation schedule