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Accueil du site → Doctorat → États-Unis → 1999 → Impact of small mammal disturbances on water and sediment yields in the Jornada Basin, southern New Mexico

State University of New York at Buffalo (1999)

Impact of small mammal disturbances on water and sediment yields in the Jornada Basin, southern New Mexico

Neave, Melissa Ruth

Titre : Impact of small mammal disturbances on water and sediment yields in the Jornada Basin, southern New Mexico

Auteur : Neave, Melissa Ruth

Université de soutenance  : State University of New York at Buffalo

Grade : Doctor of Philosophy (PhD) 1999

Résumé
This study examines water and sediment movement on a bajada in the Jornada Basin, New Mexico. Forty-five rainfall simulation experiments were conducted on 1 m2 and 2 m2 runoff plots in grassland, degraded grassland, and shrubland communities. Within the shrubland community separate experiments were conducted in shrub and intershrub environments. Regression analyses indicate that for a 30-min rainfall at approximately 130 mm h -1 , water yields on these environments are negatively related to the percentage of ground covered by vegetation and/or litter. In the degraded grassland and intershrub environments, sediment concentration is positively correlated with the average diameter of small mammal disturbances, suggesting that animal digging is an important factor controlling rates of erosion in these environments. Sediment concentration is not correlated with any surface property in the grassland or shrub environments. An analysis of water yields and sediment concentrations at 5-min intervals during the 30-min simulated rainfall experiments reveals that the influence of the above-mentioned factors on runoff and erosion is established 10 to 15-min into a rainfall event. A comparison among the different communities indicates that the shrubland (incorporating both shrub and intershrub environments) produces higher water and sediment yields than either the grassland or the degraded grassland. The physically based soil erosion model KINEROS2 is employed to model water and sediment yields from slope lengths longer than the runoff plots. In all three communities water yield declines with increasing slope length. Sediment yield, however, initially increases and then decreases in a downslope direction. The initial increase is due to sediment yield being limited by the flow’s transport capacity, which increases downslope. The subsequent decrease in sediment yield is due to sediment yield being limited by raindrop detachment capacity, which decreases downslope as flow depth increases. Sediment yields calculated for the degraded grassland and shrubland, which have the most animal disturbance, indicate that the impact of the disturbance on sediment yield (i.e. the difference between yields from surfaces with and without animal digging) is greatest on short slopes and decreases as slope length increases.

Mots clés : Ecology, Jornada Basin, Small mammal disturbances, New Mexico, Geography, Arid Biological sciences, Earth sciences, Water, Sediment yields

Présentation (Jornada NMSU)

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