• the relative impacts of types of precipitation and storm intensity
  
• the timing of precipitation events
  
• how landscape interacts to changing conditions, such as land use and climate

In recent years, the Navajo Nation has been experiencing drought conditions that may surpass the severity of all previous droughts in the 20th century. The 1987-1989 drought, attributed to above normal sea surface temperatures related to Global Warming, was the most costly natural disaster in U.S. history, with damages estimated at $39 billion for the country as a whole (Trenberth et al., 1988; Riebsame, 1991). Therefore, understanding interactions of landscape with changing environmental conditions, and their relative influence on the severity of drought, are important for natural resource planning and land use sustainability.

We are compiling meteorological information on precipitation type, intensity and timing, to examine trends that may contribute to drought intensity, and will conduct infiltrometer work on alluvial deposits, and use soil moisture probes to evaluate relative affects of precipitation intensities of both simulated and actual rainfall events on soil moisture and infiltration.

Drought and temperature increases due to climate change also affect the amount of vegetation growing on sand dune deposits. This is important for the Navajo Nation because roughly one-third of Navajo Nation land is covered with sand dunes. In wet years, areas covered by dunes are prime grazing land, but in dry years, or years with low effective precipitation (high temperatures), sand dunes may become active. (See Dunes during current drought.)

Through our studies we will produce a GIS database that links climatic changes and land use changes to land surface conditions. Spatial analyses of data will help outline cause and affect in a systematic approach that looks at the results from temporal changes of either variable, rather than addressing them independently. This approach is important because neither land use nor climate change should be examined in isolation within a natural system, and they may act in concert to produce changes in landscape stability thresholds.

This information is especially pertinent to those living in this semi-arid environment, where land use sustainability is at risk, and desertification of land threatens the livelihood and culture of local residents.

U.S. Department of the Interior - U.S. Geological Survey - Geology Discipline
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