a b s t r a c tLand use and land cover changes have complex linkages to climate variability and change, biophysical resources, and socioeconomic driving forces. To assess these land change dynamics and their causes in the Great Plains, we compare and contrast contemporary changes across 16 ecoregions using Landsat satellite data and statistical analysis. Large-area change analysis of agricultural regions is often hampered by change detection error and the tendency for land conversions to occur at the local-scale. To facilitate a regional-scale analysis, a statistical sampling design of randomly selected 10 km × 10 km blocks is used to efficiently identify the types and rates of land conversions for four time intervals between 1973 and 2000, stratified by relatively homogenous ecoregions. Nearly 8% of the overall Great Plains region underwent land-use and land-cover change during the study period, with a substantial amount of ecoregion variability that ranged from less than 2% to greater than 13%. Agricultural land cover declined by more than 2% overall, with variability contingent on the differential characteristics of regional human-environment systems. A large part of the Great Plains is in relatively stable land cover. However, other land systems with significant biophysical and climate limitations for agriculture have high rates of land change when pushed by economic, policy, technology, or climate forcing factors. The results indicate the regionally based potential for land cover to persist or fluctuate as land uses are adapted to spatially and temporally variable forcing factors.Published by Elsevier Ltd.
Se examinan la media, las máximas, las mínimas y las curvas de duración del caudal anual en la cuenca de drenaje rura l no reglamentada, del río Santa Fe en el norte de Florida, 1932–2012. El riego en el área de estudio se ha más que duplicado desde 1970, aumentando de 3.400 hectáreas a cerca de 7.300 hectáreas de tierra de regadío aproximadamente. Esto influyó en una disminución del 22% en la mínima y la media del caudal en la cuenca. Se realizan cálculos de precipitación anual se para determinar si los cambios de caudal son impulsados por los cambios climáticos o por fuentes regionales de variabilidad interanual. Varias pruebas estadísticas objetivamente detectan tendencias, roturas en la serie cronológica y cambios significativos en las características hidroclimáticas. Los caudales bajos e intermedios exhiben marcados descensos tras las roturas y se reflejan en la doble masa y en las curvas de duración del caudal anual, sin embargo, los cambios en la precipitación son casi imperceptibles. La ausencia de reglamentación del caudal aguas arriba y el mayor desarrollo urbano, así como la fuerza de las señales en los caudales bajos e intermedios, sugieren que las observadas reducciones de caudal son el resultado resultan del aumento de bombeo de aguas subterráneas para el regadío a mediados de los 70.
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