Daily disaggregation of simulated monthly flows using different rainfall datasets in southern Africa

Abstract

Study region: Selected countries in southern Africa. Study focus: The study uses a combination of a monthly rainfall-runoff model and a daily rainfall based disaggregation method to simulate daily flows. The two models were forced with different rainfall data (local and global) and the results examined to determine the major reasons for modelling success or failure. New hydrological insights for the region: There are substantial regional differences in the success of the monthly hydrological model, which inevitably affects the success of the daily disaggregation results. There are also regional differences in the success of using global rainfall data sets (Climatic Research Unit (CRU) datasets for monthly, National Oceanic and Atmospheric Administration African Rainfall Climatology, version 2 (ARC2) satellite data for daily). The overall conclusion is that the disaggregation method presents a parsimonious approach to generating daily flow simulations from existing monthly simulations and that these daily flows are likely to be useful for some purposes (e.g. water quality modelling), but less so for others (e.g. peak flow analysis).

Keywords

• Hydrological models
• Daily disaggregation
• Southern Africa
• Rainfall datasets