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

Titre : Integrated modeling of land and water resources in two African catchments : the Upper Blue Nile in Ethiopia, and the Thukela/Drakensberg in South Africa.

Auteur : Yalew, Seleshi Getahun.

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Doctor of Philosophy (PhD) 2018

Résumé partiel
Land and water are two of the most important and interacting natural resources that are critical for human survival and development. Growing population and global economic expansion are accelerating the demand for land and water for uses such as agriculture, urbanization, irrigation, hydropower, and industrialization. The land surface changes dynamically due to these demands and other socio-economic drivers. Biophysical factors such as topographic suitability, climate change, and rainfall variability further influence landuse changes and land-use change decisions. Water resources are likewise experiencing pressure from overuse, pollution, and changes in hydrologic processes as a result of both socio-economic and biophysical factors. Land and water resources are considered to have strong interactions. Although the science of this interaction is not new, the two are typically managed under separate governance systems (Le Maitre et al., 2014). As a result, land-use change and hydrology or water resources are studied usually separately. Modelers and model developers reproduced the existing separation in governance of land and water resources in their respective models, which gave rise to mild treatment of one of the resources when analyzing the other. The result is that hydrology and water resources are often considered to be processes and resources affected only by biophysical components, ignoring anthropogenic contributions that may actually influence such characteristics through direct effects on land-use, for instance. The need to understand and explicitly represent the interaction between water resources on the one hand and land-use changes with its drivers on the other is imperative for sustainable management of integrated natural resources management in general and land and water resources management in particular. In recent years, interesting sub-disciplines such as ‘socio-hydrology’ are emerging which recognize and emphasize the importance of socioeconomic and anthropogenic effects on hydrologic and water resources analysis. Interaction and feedback between land-use and water resources is still not explicitly and dynamically represented in most scientific modeling tools related to land and water, however. Furthermore, often due to limitations of access and computing resources, frameworks for communicating integrated assessment and modeling in a way that can be operational to resource managers and decision makers related to such resources is limited. This is especially evident in developing regions. In this study, an integrated modeling approach is devised to modeling and testing interactions of land and water resources with focus areas in two selected basins in Africa : the Upper Blue Nile in Ethiopia, and the Thukela/Drakensberg in South Africa. The study focuses on analyzing land-use change drivers, assessing dynamic feedback between land-use and hydrology, and developing methods and tools for improved assessment and model representation in integrated modeling. For facilitating integrated modeling and analysis of land and water resources, various open-source tools and standards for simplified data access, computation and communication of results of integrated analysis are developed and tested. First, land-use suitability was computed using spatial and biophysical indicators in the Blue Nile and the Thukela basins. Methods and techniques were developed for online assessment of land-suitability using global and open source datasets. Based on the land-use suitability indicators developed thus far and in light of various socio-environmental land-use change drivers, respective land-use change models were developed and parameterized for the two basins.

Sujets  : water resources African countries catchment areas land resources data analysis spatial analysis

Présentation et version intégrale