Activities > Climate History and Landscape Change [ || Soil Moisture || Geology & Soil Texture || Biological Soil Crusts || Fire || Vegetation Dynamics || Soil Compaction || Wind Erosion || Climate || Repeat Photography || Land Use History || Spatial Modeling || ] Climate, particularly precipitation, alters the desert landscape and the rate of recovery from natural and human disturbances. Yet, short-term (historical) natural climate variability and its influence on desert landscapes is not well known. The problem, therefore, is to understand climate variability and its effect on the physical components of the Mojave Desert ecosystem. Methodology Field studies on alluvial processes in the Mojave Desert provide evidence of the frequency and magnitude of hillslope runoff, debris-flow activity, and floodplain alluviation in desert washes. Highlights and Key Findings Although the climate and landscape of the Mojave Desert, or any desert for that matter, are typically viewed as static and unchanging on historical time scales, this research demonstrates that climate, particularly precipitation, has varied substantially, and that the alluvial landscape is dynamic, changing in direct response to climate variation in many cases. Precipitation in the Mojave Desert region varied substantially in the 20th century largely in response to global climate variability, specifically, El Niño/Southern Oscillation and the Pacific Decadal Oscillation. Multidecadal episodes of relatively moist conditions have alternated with dry conditions. The past two decades have been unusually wet with increased frequency of high- and low-intensity precipitation. The multidecadal episodes, particularly the drought-like conditions of 19421975 and the wet episode of 19761998, are contemporaneous with changes in the Pacific Decadal Oscillation. This relation suggests that the long-term climate of the Mojave Desert may be predictable. If so, the desert may undergo (or is now undergoing) drought-like conditions similar to those of 19421975. The implications for land management are that policies established from research done in the past two decades may not apply in another, drier climate scenario. Moreover, climate variation in a majority of the cases altered the frequency of surface runoff and sediment yield, the occurrence of debris flows, and alluviation in the major washes. The net effect has been temporal clustering of geomorphic activity that coincides with the main episodes of wet and dry climate as discussed above. Products Hereford, R., Webb, R.H., and Longpre, C.I., 2004, Precipitation history of the Mojave Desert region, 1893-2001: U.S. Geological Survey Fact Sheet 117-03, 4 p. Hereford, R., and Longpre, C., 1998, Climate history of the Mojave Desert region, 1892 -1996, including data from 48 long-term weather stations and an overview of regional climate variation, USGS website. [ || Overview || Activities || Products || Photo Gallery || Glossary || Links || Feedback || Sitemap || ] |
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