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

Titre : A semi-distributed catchment hydrology model for simulation of land use change, streamflow and groundwater recharge

Auteur : Carlile, Paul William

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 2007

Résumé
Improvements in understanding of catchment hydrology will come from an ability to accurately disaggregate and connect surface and sub-surface hydrological components. This PhD thesis research has developed and investigated the ability of a rainfall-runoff, recharge-discharge model to simulate the hydrological fluxes in a catchment at various scales. The model has been developed to be a management tool for examining the effect of land-use change on stream flow and recharge within data poor catchments. Therefore the Little River Catchment located in central western New South Wales was used as a case study to test the approach. A successful conceptual rainfall-runoff model with relatively few parameters is used as a starting point for model development. This takes the form of a top-down modelling approach. The model was further developed so that it could integrate physical characteristics of the catchment while maintaining a simple model structure. The aim is the development of a semi-distributed catchment hydrology model which can be used as an investigative tool for the effects of land-use change on the flux of water at the surface and sub-surface. The model has been designed so as not to require calibration prior to simulation of stream flow, as many real catchments are ungauged for stream flow. The model aims to utilize datasets typically available for catchments throughout Australia. The use of vegetation and soil types in directly estimating transpiration and deep drainage within the model allows the effects of various land-use scenarios to be tested. The approach has been designed to be augmented with contaminant mobilisation and transport schemes, in particular to assist prediction of salt loads and concentrations throughout the catchment. The results presented show that the final distributed model is able to give reasonable estimates of stream flow, evapotranspiration and recharge over time, while being sensitive to land-use change such as increases or decreases in forest cover. This research presents a meta-modelling approach to determine transpiration and recharge of shallow aquifers. This unique approach first uses a complex plot scale soil-water infiltration model to identify relationships for transpiration and recharge that can be used at the field scale in the distributed model. This meta-modelling approach, coupled with the spatial disaggregation of the catchment into management units based on soils, vegetation, topography and groundwater flow systems allows the model to be sensitive to land-use change while avoiding the complexity of other physical-based distributed models. Future research should examine the accuracy of model components in other more intensively studied catchments.

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