Date of this Version
A computational model was developed to estimate evapotranspiration (ET) in the Platte River ecosystem of central Nebraska. Data used in the model were mostly derived from the literature, although leaftemperature data were collected to estimate species transpirationcoefficients.
Preliminary estimates for ET are 35.5 in per yr during the April-tooctober growing season. Riparian forest accounted for 30% of the total ET, followed in order of importance by open-water evaporation, forested islands, herbaceous riparian-transpiration, sandbar evaporation, and then hcrbaceous island-vegetation, which accounted for only 10% of the total ET.
The Platte River has changed markedly during the last 40 years, with reduced flows and narrowed channel-width. Much riparian forest has grown up in that time and vegetated islands occupy a greater percentage of the remaining channel than previously. A comparison of ET rates between the 1930s and 1970s was attempted, using the computational model developed. Total ET rates in the 1930s were about the same as today (37.3 in per yr) but proportion by habitat differed greatly, with open-water evaporation probably accounting for about one-half the total ET then.
The total loss due to evapotranspiration between Kingsley Dam and Duncan, Nebraska, from Platte River ecosystems (except for wet-meadow and cropland) was estimated to be 379,000 acre-feet per year.