Measuring Floodplain Inundation Using DielAmplitude of Temperature

Abstract

Assessment of inundation patterns across large and remote floodplains is challenging andcostly. Inexpensive loggers that record the damping of the diel amplitude of temperature (DAT)when submerged compared to overlying air can indirectly indicate inundation. We assessed theefficacy of this approach in tropical, subtropical, and temperate floodplains by comparing directwater level measurements using pressure transducers with the indirect indication of inundationascertained from the DAT at the same location. The approach worked better in tropical than insubtropical and temperate floodplains. However, the relatively small DATs of air in humid anddensely vegetated settings made estimation of inundation more challenging compared to the drier andless vegetated settings, where a large diel range of air temperature was markedly damped beneath thewater. The indirect temperature approach must be calibrated for a particular ecosystem using directwater-level measurements to define DAT thresholds that are indicative of submergence of the sensors.Temperature provides an inexpensive indicator of duration of inundation that can be particularlyuseful in studies of large and remote floodplains, although the development of inexpensive sensorsthat directly measure submergence (e.g., by resistivity) will likely become a better option in the future.