|Houser, P - NASA|
|Syed, K - UNIV. OF ARIZ.|
Submitted to: Spatial Patterns in Hydrological Processes Observations and Modelling
Publication Type: Book / Chapter
Publication Acceptance Date: March 29, 1999
Publication Date: N/A
Interpretive Summary: Arid and semi-arid regions account for approximately one-third of the land mass of earth. These regions are experiencing continued pressure from population growth in many parts of the world. Water is a critical resource in these regions and is often in short supply. Detailed study of water resources and the hydrology of semi-arid regions is important if we are to continue to populate and use these regions. The Walnut Gulch Experimental Watershed, operated by the U.S. Dept. of Agriculture, Agricultural Research Service was established to observe and better understand water movement and the effects of land use on watershed hydrology in semi-arid regions. Our understanding of water and hydrology in semi-arid regions has been greatly enhanced through numerous studies of rainfall, runoff, and soil moisture patterns at this experimental watershed. Rainfall was found to be highly variable and dense raingauge networks are required to accurately predict flood runoff. It was also found that flood runoff is often reduced significantly when flood waters travel down dry stream channels. New technologies such as data sensed from airplanes and satellites were also found to be useful in understanding and predicting water use and movement in semi-arid settings.
Technical Abstract: The complex hydrological process of semi-arid regions, and their resulting patterns is the focus of this chapter. The research presented here was undertaken at the Walnut Gulch Experimental Watershed near Tombstone, Arizona, which is operated by the USDA-ARS Southwest Watershed Research Center. The extremes in rainfall and temperature in this region lead to great spatial heterogeneity in soil hydrological processes. Observations from a series of nested watershed gauging stations, a dense network of precipitation gauges, and remotely sensed soil moisture estimates, in concert with specialized remote sensing, surface characterization, and numerical simulation have lead to numerous insights into the nature, causes, and effects of hydrologic spatial patterns in this semiarid watershed. The nature, representation, and interrelation of spatial rainfall patterns and their impact on the spatial distribution of runoff and soil moisture is described. The representation of this spatial behavior through the integration of observations in several distributed hydrologic model is also discussed. Additionally, the role of data assimilation in this environment is assessed.