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sur le développement des zones arides et semi-arides

Titre : The hydrological flux of organic carbon at the catchment scale : a case study in the Cotter River catchment, Australia

Auteur : Sabetraftar, Karim

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 2005

Description
Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is generally assumed that biomass and soil carbon are the only relevant pools in a landscape ecosystem. However, recent findings have suggested that significant amounts of organic carbon can dissolve (dissolved organic carbon or DOC) or particulate (particulate organic carbon or POC) in water and enter the hydrological flux at the catchment scale. A significant quantity of total organic carbon (TOC) sequestered through photosynthesis may be exported from the landscape through the hydrological flux and stored in downstream stocks.¶ This thesis presents a catchment-scale case study investigation into the export of organic carbon through a river system in comparison with carbon that is produced by vegetation through photosynthesis. The Cotter River Catchment was selected as the case study. It is a forested catchment that experienced a major wildfire event in January 2003. The approach is based on an integration of a number of models. The main input data were time series of in-stream carbon measurements and remotely sensed vegetation greenness. The application of models to investigate diffuse chemical substances has dramatically increased in the past few years because of the significant role of hydrology in controlling ecosystem exchange. The research firstly discusses the use of a hydrological simulation model (IHACRES) to analyse organic carbon samples from stream and tributaries in the Cotter River Catchment case study. The IHACRES rainfall-runoff model and a regionalization method are used to estimate stream-flow for the 75 sub-catchments. The simulated streamflow data were used to calculate organic carbon loads from concentrations sampled at five locations in the catchment.¶ ...

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