Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Royaume-Uni → 2005 → Scaling approaches to the modelling of water, sediment and nutrient fluxes within a semi-arid landscape, Joranta Basin, New Mexico

University of London (2005)

Scaling approaches to the modelling of water, sediment and nutrient fluxes within a semi-arid landscape, Joranta Basin, New Mexico

Mueller, Eva Nora.

Titre : Scaling approaches to the modelling of water, sediment and nutrient fluxes within a semi-arid landscape, Joranta Basin, New Mexico

Auteur : Mueller, Eva Nora.

Université de soutenance : University of London

Grade : Doctor of Philosophy (Ph.D.) : 2005

Résumé
A fieldwork-integrated modelling approach was employed to enable the quantification of water, sediment and nutrient fluxes within and between shrubland and grassland associations in a semi-arid ecosystem, the Jornada Basin in the Chihuahuan Desert, New Mexico. The aim of this thesis is the evaluation of scaling approaches to the numerical modelling of these fluxes combined with the appropriate application of scaling tools for model parameterisation. Special emphasis is placed on the investigation of parameter and process scaling and the applicability of scaling tools to interpolate and extrapolate field data, disaggregate remotely sensed data and aggregate model parameters. Extensive field studies were carried out to acquire detailed understanding of the spatial distribution of hydrological, soil- and nutrient-related model parameters within black grama grassland and creosote, tarbush and mesquite shrublands. The statistical and geostatistical analysis of the field data resulted in the development of scaling techniques that enabled the spatially realistic reproduction of the small-scale variability and connectivity features of model input parameters. Spatially distributed, process-orientated models with a 2-m resolution were employed to enable an adequate representation of model input parameter and an appropriate reproduction of overland flow characteristics and sediment- and nutrient- transport processes. Based on these results, the models were upscaled to a resolution of 10-m under specific evaluation of process and parameter scaling issues. The upscaled model versions were then employed for the flux quantification within and percentage change of fluxes between shrubland and grassland associations. The modelling studies provided important insights in the stability of grassland-shrubland boundaries as a function of nutrient depletion and water-resource enrichment for the grassland by the action of overland flow. It was hypothesised, that external forces such as overgrazing or climatic variations might potentially disturb this stability, which consequently leads to the invasion of shrubs into the grassland.

Présentation : EThOS (UK)

Accès au document : Proquest Dissertations & Theses

Page publiée le 6 juin 2009, mise à jour le 3 février 2017