Performance of rainfall–runoff models in reproducing hydrological extremes: a case of the River Malaba sub-catchment

Abstract

Daily River Malaba flows recorded from 1999 to 2016 were modelled using seven lumped conceptual rainfall–runoff models including AWBM, SACRAMENTO, TANK, IHACRES, SIMHYD, SMAR and HMSV. Optimal parameters of each model were obtained using an automatic calibration strategy. Mismatches between observed and modelled flows were assessed using a total of nine “goodness-of-fit” metrics. Capacity of the models to reproduce historical hydrological extremes was assessed through comparison of amplitude–duration–frequency (ADF) relationships or curves constructed based on observed and modelled flow quantiles. Generally, most of the hydrological models performed better for high than low flows. ADF curves of both high and low flows for various return periods from 5 to 100 years were well reproduced by AWBM, SAC, TANK and HMSV. ADF curves for high and low flows were poorly reproduced by SIMHYD and SMAR, respectively. Overall, AWBM performed slightly better than other models if both high and low flows are to be considered simultaneously. The deviations of these models were larger for high than low return periods. It was found that the choice of a “goodness-of-fit” metric affects how model performance can be judged. Results from this study also show that when focusing on hydrological extremes, uncertainty due to the choice of a particular model should be taken into consideration. Insights from this study provide relevant information for planning of risk-based water resources applications.

Water availability trends across water management zones in Uganda

“…The inversed distance weighed (IDW) interpolation approach (Shepard, 1968) was adopted to fill-in the missing precipitation records. The suitability of IDW interpolation for the precipitation over the study area was recently demonstrated by Chelangat and Abebe (2021) and Mubialiwo et al (2021a).…”

“…The suitability of IDW interpolation for the precipitation over the study area was recently demonstrated by Chelangat and Abebe (2021) and Mubialiwo et al . (2021a).…”

“…This requirement of validating satellite or reanalysis products prior to their application was also considered in other past studies across Uganda. Examples of such studies include Mubialiwo et al (2020Mubialiwo et al ( , 2021aMubialiwo et al ( , 2021b and Onyutha et al (2020). The procedure followed in validating CFSR can be found in section 2.2.2.…”

“…In Uganda, a number of studies (Kansiime et al ., 2013; Nyeko‐Ogiramoi et al ., 2013; Egeru et al ., 2019; Mubialiwo et al ., 2020; 2021a; 2021b) have been conducted to understand variations in hydro‐climatic variables such as precipitation, potential evapotranspiration (PET), river flow, and temperature. Most of these studies were conducted on the scales of a catchment, sub‐catchment, or region.…”

Hydrodynamic Modelling of Floods and Estimating Socio-economic Impacts of Floods in Ugandan River Malaba Sub-catchment

“…Simulated daily rainfall-runoff was adopted from the earlier study (Mubialiwo et al 2021b). The series covered the period 1999-2016 totalling to 18 years.…”