THE IRRIGAGE: A NON?EVAPORATING IN?FIELD PRECIPITATION GAGE

Abstract

Construction details and measurement data associated with a non-evaporating, in-field precipitation gage (theIrriGage) are presented. IrriGages are fabricated using standard pieces of PVC pipe and fittings. A plastic bottle is used tostore collected water and is attached to the bottom of the collection barrel. Collected water is only exposed to the atmospherethrough the collection barrel via a 9.5-mm drain hole. Evaporative losses from IrriGages were compared to losses from otherprecipitation collection devices in an in-field device evaporation study during the 2001 summer. During the study period,air temperatures often exceeded 38.C and daily grass-reference evapotranspiration rates exceed 8 mm/day. Evaporationlosses from IrriGages were negligible over several weeklong measurement periods, while substantial evaporation losses wereassociated with standard rain gages and other collection devices.