ANALYZING ECOHYDROLOGY OF SUBIRRIGATED MEADOW, DRY VALLEY AND UPLAND DUNE ECOSYSTEMS USING REMOTE SENSING AND IN-SITU ESTIMATIONS IN THE SEMIARID SAND HILLS REGION OF NEBRASKA, USA

Authors

Nathan C. Healey, University of Nebraska-LincolnFollow

Date of this Version

Fall 12-5-2011

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Natural Resource Sciences (Climate Assessment and Impacts), Under the Supervision of Professors Ayse Irmak and John D. Lenters. Lincoln, Nebraska: December, 2011

Copyright (c) 2011 Nathan Charles Healey

Abstract

Nebraska’s dependence upon the High Plains (Ogallala) Aquifer for agricultural production is vital to the state’s economy, ecology and hydrology. The Sand Hills region (58,000 km²) of Nebraska is a unique system of lakes, (~5%) wetlands, (~10%) subirrigated meadows, (~20%) dry valleys and (~65%) upland sand dune ecosystems. Understanding how each of these land cover types reacts to climate conditions of different water limitations is vital to regional water resource management. This research explores the ecohydrological behavior of different land cover types at the Gudmundsen Sand Hills Research Laboratory (GSRL) near Whitman, Nebraska in the heart of the Sand Hills region of Nebraska by using remote sensing and in-situ estimations of energy partitioning. By employing satellite technology and micrometeorological instrumentation this research establishes a better understanding how energy partitioning, and resulting evapotranspiration (ET), differs between different vegetative communities. We present findings of diurnal and seasonal estimates of energy partitioning as well as daily estimations of ET from both satellite image processing and in-situ observations by Bowen ratio energy balance systems (BREBS). This research also employed different techniques to estimate energy partitioning via remote sensing by adjusting radiation, wind speed, and stability parameters to better represent areas with high topographic relief. The last focal point of this research was to analyze how energy partitioning and ET varied both spatially and temporally under different climate conditions between 2004 (normal year), 2006 (dry year), and 2009 (wet year).

Adviser: John D. Lenters