Rwasoka D.T.,Upper Manyame Subcatchment Council |
Madamombe C.E.,Digby Wells Environmental |
Gumindoga W.,Box MP |
Kabobah A.T.,University of Energy and Natural Resources
Physics and Chemistry of the Earth | Year: 2014
Hydrologic modelling lies at the core of hydrology and water resources management. Attempts at gaining a holistic grasp on model robustness, hydrologic theory and processes have inadvertently led to models that are not-well structured or too complex to apply in arid and semi-arid catchments and in Africa, in particular. In view of this, this paper reports on the application of a monthly parsimonious hydrologic model in two catchments in Zimbabwe, the Nyatsime and Upper Save river catchments. The two (2) parameter monthly parsimonious GR2M model was applied. The inputs were rainfall and potential evapotranspiration. Measured discharge was used for calibration and validation. Calibration and uncertainty analysis were done using the Differential Evolution Adaptive Metropolis (DREAM) algorithm. The performance of the GR2M model was evaluated using ten (10) model performance metrics. Parameter indentifiability was analysed on the basis of the shape of the posterior distribution of parameters. Parameter and total uncertainty were analysed in the context of the formal Bayesian DREAM approach. The 10 performance evaluation metrics showed that the model performed satisfactorily during calibration and validation in terms of the overall fit of observed and simulated stream flows, low flows and the runoff volumes. The Nash-Sutcliffe efficiency (NSE) was >0.85, the Kling-Gupta Efficiency (KGE) was >80% and Volume Efficiency was >59% during calibration. Slight performance drops were noted during validation except for the NSE in Nyatsime catchment whilst the KGE remained relatively high. The validation NSE was >0.65, the Kling-Gupta Efficiency (KGE) was >71% and Volume Efficiency was >55%. Calibrated parameters values showed good time-stability and were well identifiable with posterior parameter distributions having Gaussian shapes. Parameter uncertainty, in relation to total uncertainty was low. Parameter uncertainty constituted about 7% of the total uncertainty region. It was concluded that, although the model only had two parameters, the model performed quite satisfactorily in the simulation of monthly flows which makes it a good tool for operational hydrology and water resources modelling, planning and management especially in regions with inadequate data. © 2013 Elsevier Ltd.
Bhunu C.P.,Box MP
Journal of Biological Systems | Year: 2014
Child neglect and abuse has been linked with the growth in the number of street kids for some time. A mathematical model is used to explore the impact of peer influence and child abuse in the presence of removal of street kids from the streets into children's homes/foster homes and improvement in the welfare of adults. The threshold quantity known as the reproduction number and equilibria for the model are determined and analyzed. Results from this study suggest that removal of street kids from the streets into children's homes/foster homes and improving the welfare of adults have the potential to reduce the number of children living in the streets. Interestingly, our results illustrate that adult peer influence leading to child abuse of children makes the problem of street kids worse than any other factor. To effectively control the growth in the number of street kids require strategies that address both economic and social factors affecting children and their guardians. Addressing only an issue affecting one group like guardians through improvement of their welfare may not be enough to stem the growth in the number of street kids as some would be turning to the streets due to negative peer influence among children. © 2014 World Scientific Publishing Company.
Mafuta P.,Box MP |
Mushanyu J.,Box MP |
Mushayabasa S.,Box MP |
Bhunu C.P.,Box MP
World Journal of Modelling and Simulation | Year: 2013
A deterministic model for transmission dynamics of Trichomonas vaginalis in a population with bisexuals is formulated and analysed. The disease free equilibrium point has been shown to be globally asymptotically stable when the reproduction number is less than a unity. Furthermore, the endemic equilibrium point has been shown to be locally asymptotically stable and globally asymptotically stable for when the reproduction number is greater than a unity, using the Centre manifold theory and Liapunovs functional approach, respectively. Analysis of the reproduction number has shown that an increase in the number of infected bisexuals result in an increase in the number of infectives among heterosexuals and vise-versa. This suggests that straight women are turning into bisexuals already infected and that bisexuals are linked to straight females indirectly by males. Simulations results has shown that treatment is the major parameter in controlling the spread of the infection.