Larry Pochop

RECENT GLACIER CHANGES IN THE WIND RIVER RANGE, WYOMING

Parallax measurements on matching aerial photograph stereopairs from 1958 and 1983 were used to calculate the ice lost from Dinwoody Glacier in the Wind River Range of Wyoming. The ice remaining in Dinwoody Glacier was measured using a portable radio echo-sounder. Isopach maps of lost ice thickness and remaining ice thickness in the glacier were constructed from these point measurements. Calculations of lost and remaining ice volumes, converted to water-equivalent values, were derived from planimetric measurements from these isopach maps. The water equivalent remaining in Dinwoody Glacier is approximately equal to that lost between 1958 and 1983. Should this rate of downwasting and retreat continue, Dinwoody Glacier will disappear in 27 years, with significant adverse impacts on late summer and early fall water supplies for downstream irrigators and instream flow needs. [Key words: glaciers, glacier runoff, radio echo-sounding, Wind River Range, Wyoming.]

Glacier Impacts on Summer Streamflow in the Wind River Range, Wyoming

AbstractThe Wind River Range (WRR) of Wyoming is host to approximately 63 glaciers. Extensive research has been conducted using remote imagery to estimate the recent area and volume changes of these glaciers with the goal of estimating the potential effects of these changes on watershed streamflow. Results show that the glaciers were mostly in recession since 1966, the beginning of the study period. The current research was performed to supplement results from the remote imagery analyses. In this paper, streamflows from glaciated and nonglaciated watersheds in the WRR for the period 1967–1992 were analyzed. The difference in July-August-September (JAS) watershed flow magnitude for the 26-year period between glaciated (Green River and Bull Lake Creek) and nonglaciated (East Fork River and Wind River) watersheds ranged between 8 and 23%. As expected, the effects of glaciers on local streamflows during JAS were shown to be much greater than that of ice melt alone. The influence of glaciers accounted for 23–5...

Design of turbulent fountain irrigation trash screens

Floating trash in surface irrigation waters can block or reduce the flow of irrigation water and significantly increase irrigation costs. Dimensional analysis was applied to experimental data to develop equations for designing irrigation trash screens and for modifying a trash screen to compensate for variations in water flow. The equations were based on providing adequate horizontal flow across the screen to float aquatic algae off the screen and thereby prevent blockage.

Frequency and Duration of Drought in the Upper Green River Basin, Wyoming, USA

The limited length of instrumental streamflow data impacts the true magnitude of natural interdecadal variability of water delivered from the UGRB. This limited period of instrumental record can be expanded by utilizing proxy records (reconstructed streamflow) derived from tree rings. Two reconstructed streamflow datasets are now available for the Green River near Green River, UT (Stockton and Jacoby, 1976; Woodhouse et al., 2006), and a new preliminary reconstruction has been developed for the Green River near Green River, Wyoming (Woodhouse et al., 2006). Also, recent research has resulted in the development of nine streamflow reconstructions spatially located throughout the UGRB (Barnett et al., 2008). The proposed research would use these streamflow reconstructions to assess patterns (temporal and spatial) and sources of streamflow variability in the UGRB. An investigation of long-term streamflow variability, focusing on extreme events such as mega-droughts, will be performed. The research will result in the development of probabilistic drought forecasts. Salas et al. (2005) provides drought definitions and equations that can be utilized by water planners in storage dependent systems. Loaiciga (2005) utilized the compound renewal process, which generalizes the Poisson process, to calculate return periods for drought events. This may result in frequency – duration curves for UGRB drought. Such probability curves can then be analyzed in light of Compact agreements to answer questions such as, “How often might the outflow from the UGRB fail to meet 10-year delivery obligations?”