[1] The evaluation of the relationship between satellitederived vegetation indices (normalized difference vegetation index and normalized difference water index) and soil moisture improves our understanding of how these indices respond to soil moisture fluctuations. Soil moisture deficits are ultimately tied to drought stress on plants. The diverse terrain and climate of Oklahoma, the extensive...

Annual growth of semiarid tree species is generally limited by a period of water deficit and this relationship can be reflected in interannual variation in tree-ring width of semiarid species such as Pinus edulis, a piñon pine that is widely distributed across the southwestern United States. Tree-ring width of P. edulis and other semiarid tree species is most frequently related to annual precip...

the zoning of phenomena based on geographical location has a long history; any geographical zone is a part on ground level, which possesses noticeable internal consistency in terms of its existing phenomena and processes. agroclimatic zoning is mainly purposed to determine agroclimate regions and to evaluate these zones based on their relative utility in order to cultivate varieties of agricult...

Fuel load and fuel moisture content are crucial parameters in estimating bushfire risk. However, current measures of these parameters are not spatially distributed within fire districts; the district-level indices are derived from pointbased estimates at sparsely located stations. In addition, they are based on meteorological inputs alone, rather than observations, and are the major sources of ...

Satellite-derived vegetation indices extracted over locations representative of midwestern U.S. cropland and forest for the period 1990–94 are analyzed to determine the sensitivity of the indices to neutron probe soil moisture measurements of the Illinois Climate Network (ICN). The deseasoned (i.e., departures from multiyear mean annual cycle) soil moisture measurements are shown to be weakly c...

Drought is a wide-spread problem seriously influencing durum wheat (Triticum durum Desf.) production and quality, but development of resistant cultivars is hampered by the lack of effective selection criteria. The objective of this study was to evaluate the ability of several selection indices to identify drought resistance cultivars under a variety of environmental conditions. Twenty four duru...

Spatial predictions of soil moisture content in arid lands are necessary for soil survey, land evaluation, hydrological modeling, land use planning and sustainable land use. Multiple-linear regression models with land use and terrain indices were developed to spatially predict soil moisture using six methods. The performance of six models was evaluated using 13 indices based on biweekly-measure...

This dissertation describes efforts to overcome the challenges in designing in situ soil moisture observation network. The surface soil moisture data collected at two spatial scales in a working field in Iowa throughout the growing seasons in 2004 to 2008 were used to describe the spatio-temporal characteristics of soil moisture at field scale. The rank stability analysis was used to identify t...

Proxies such as plant macrofossils, humification indices and testate amoebae have been developed to reconstruct past hydrological variability in ombrotrophic peatlands. Reconstructions based on these approaches have resulted in records of decadalto centennial-scale moisture variability in regions of North America and elsewhere. Although the various peatland moisture proxies generally show signi...

Vigorous discussions and disagreements about the future changes in drought intensity in the U.S. Great Plains have been taking place recently within the literature. These discussions have involved widely varying estimates based on drought indices and model-based projections of the future. To investigate and understand the causes for such a disparity between these previous estimates, the authors...