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

Accueil du site → Doctorat → Allemagne → 2006 → An integrated, landscape-based approach to model the formation and hydrological functioning of wetlands in semiarid headwater catchments of the Umzimvubu River, South Africa

Friedrich-Schiller-Universität Jena (2006)

An integrated, landscape-based approach to model the formation and hydrological functioning of wetlands in semiarid headwater catchments of the Umzimvubu River, South Africa

Helmschrot, Jörg

Titre : An integrated, landscape-based approach to model the formation and hydrological functioning of wetlands in semiarid headwater catchments of the Umzimvubu River, South Africa

Auteur : Helmschrot, Jörg

Université de soutenance : Friedrich-Schiller-Universität Jena

Grade : Dr rer nat 2006

Résumé
Wetlands are very important elements of the la ndscape in almost every environment. Address- ing the continued loss of wetland area worldwide, wetlands are recognized as highly vulnerable with regard to natural and anthropogenic system changes. Consequently, the research of their natural and socio-economical functions, importan ce for the water and nutrient cycles and their role as wildlife habitats received increasing scient ific and public awareness in the past decades. The landscape of the semi-arid Eastern Cape Pr ovince, South Africa, is characterized by the occurrence of different types of palustrine wetl ands. Intensive afforestation in the headwaters of the Umzimvubu catchment since 1989 has changed downstream wetland characteristics, but little attention was given to evaluate and quant ify these impacts. Addressing this research deficit, the main objectives of this dissertati on are the development of an integrated, land- scape-based research approach to improve the understanding of the formation, functioning and dynamics of wetlands and the prognostic modeling and assessment of afforestation im- pacts on these wetland systems. The conceptual and methodological approach of this dissertation is based on three individual aspects : i) observation and data mining ; ii) integ rated system analysis ; and iii) system modeling and assessment integrating empirical field studie s, laboratory analysis, GIS and remote sensing techniques, system analysis and process-orien ted, plant growth and hydrological modeling, This integrated research approach provides in formation regarding a generalized understanding of dominant environmental processes at wetland and catchment scale and the impact of affor- estation on wetland and basin hydrology. By means of this effort three main wetland ty pes, being different in terms of landscape posi- tion, extent and size of the tributary catchment , soils, vegetation composition and hydrological dynamics, could be identified. The hydrodynamics of plateau and slope wetlands are mainly controlled by recharge mechanisms, while larg er valley bottom wetlands are driven by inter- linked ground-/surface water dynamics, discharge/ recharge processes and direct rainfall input. Coupling plant growth and hydrological modeling, it was found that wetland dynamics and their landscape functions will be influenced by afforestation in terms of altered re- charge/discharge mechanisms ; reduced base flows addressed to increased interception losses and reduced water retention capability as a result of net loss of wetland ar ea. In addition, such changes will affect environmental functions an d biodiversity due to habitat loss and altera- tions. Integrating the results and information of the present study, an integrated landscape model was developed aiming to characterize wet land formation and emphasizing impacts of human activities on past and recent wetland and landscape dynamics.

Mots clés  : wetlands, landscape model, hydrological modeling, afforestation, South Africa

Présentation

Version intégrale (12,5 Mb)

Page publiée le 12 avril 2020