Climate and Land-Atmosphere Studies Related to Drought


Lawrence Hipps

Document Type

Conference Paper

Journal/Book Title/Conference

Spring Runoff Conference

Publication Date



Droughts are endemic in the Intermountain region. But they do not appear to occur randomly, as the climate of the region is characterized by intermittent wet and dry cycles. Understanding their effects on ecosystems and society requires investigation of both climate and land-atmosphere interactions. Here we address three main issues related to climate, land processes and drought. These include: the climatology of drought in the region, especially the occurrence, magnitude and duration of wet and dry episodes; exchanges of energy and water between the surface and atmosphere in mountain watersheds; and reliable measurements and mechanistic models of water use by turfgrass in urban environments. We explore these facets of drought and water resources, which are connected to climate and biophysical processes. The time series of temperature and precipitation in the modern climate record are being analyzed using spectral, cross spectral and other approaches. Future plans include extending the record back using tree ring estimates of historical precipitation. The energy and water balance of mountain watersheds plays a critical role in affecting water resources in the region. An eddy covariance system has been sited over a meadow in the TW Daniels Experimental Forest. Measurements include the surface fluxes of heat, water vapor and CO2, as well as net radiation and soil heat flux. These results will quantify the changes in energy and water balance during the year. When combined with other hydrological measurements at the site, they provide results that can be used to validate hydrologic models for the fate of water in mountain watersheds. Finally, a significant portion of available water resources in urban regions of the West is consumed by irrigation of residential landscapes, especially turfgrass. Reliable measurements of the actual water used in these locations are lacking. Current models used to estimate water use and schedule irrigation are rather empirical and not yet evaluated against quality measurements. An eddy covariance system is measuring water vapor fluxes over a large turfgrass plot near USU, and has been operating for several years. Hourly values of the energy balance and water use are calculated over the growing season. These values will be used to evaluate current empirical models. Future efforts will be directed to the development of a mechanistic model that includes processes such as stomatal conductance and the advection of warm and dry air from the surrounding lands.