Research School for Socio-Economic and
Natural Sciences of the Environment
Research School for Socio-Economic and
Natural Sciences of the Environment

Aline Maraci Lopes Saraiva Okello

Date: 02 May 2019
Location: Delft

Dissertation title: 

Improved hydrological understanding of a semi-arid subtropical transboundary basin using multiple techniques - the Incomati River Basin

Group: IHE Delft, Hydrology and Water Resources
Promotor: Prof.dr. S. Uhlenbrook
Copromotors: P. van der Zaag and dr. I. Masih


This thesis aims at improving the hydrological process understanding of the semi-arid and transboundary Incomati river basin to enable better water management. Comprehensive statistical and trend analysis of rainfall and streamflow were conducted, and the Indicators of Hydrological Alteration tool was deployed to describe the streamflow regime and trends over time. Hydrograph separation using long-term hydrochemical data at seasonal scale, and hydrochemical and isotope data at event scale were performed to quantify runoff components. A novel methodology to calibrate recursive digital filters using routinely collected water quality data was tested in the catchment. This method allows for estimation of daily baseflow from daily streamflow data. Dominant runoff generation zones were mapped using the novel Height Above Nearest Drainage approach, combined with knowledge of the geology of the catchment. The hydrological model STREAM was then employed, informed by the runoff generation zones mapping and the process understanding gathered in the catchment.