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Dirwai, T. L.

Publications and source records attributed to Dirwai, T. L..

2 recordsLinked to original sources

Water Resource Management: IWRM strategies for Improved Water Management. A Systematic Review of Case Studies of East, West and Southern Africa.

ObjectiveThe analytical study systematically reviewed the evidence about the IWRM water strategy model. The study analysed the IWRM strategy advances and practical implications it had, since inception on effective water management in East, West and Southern Africa. MethodsThe study adopted the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) and the scoping literature review approach. The study searched selected databases for peer-reviewed articles, books, and grey literature. DistillerSR software was used for article screening. A constructionist thematic analysis was employed to extract recurring themes amongst the regions. ResultsThe systematic literature review detailed the adoption, policy revisions and growing/emerging policy trends and issues (or considerations) on IWRM in East, West and Southern Africa. Thematic analysis derived four cross-cutting themes that contributed to IWRM strategy implementation and adoption. The identified four themes were donor effect, water scarcity, transboundary water resources, and policy approach. The output further posited questions on the prospects, including whether IWRM has been a success or failure with the African water resource management fraternity. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

scientific communication and education

Moistube ™ Irrigation (MTI) Discharge Under Variable Evaporative Demand

We investigated the conceptual capability of Moistube irrigation to discharge under zero applied positive pressure under varied climatic conditions by inducing an artificial evaporative demand (Ed) or negative pressure around moistube tubing. This was premised on the null hypothesis that an artificially induced Ed or negative pressure does not impact moistube discharge. Moistube tubing was enclosed in a 1 m long PVC conduit. A 20 l water reservoir placed on an electronic balance provided a continuous supply of water whilst a three-speed hot air blower facilitated the radiative factor and advection process. The procedure was conducted under varied climatic conditions of air velocities (ua) 1.2 m.s-1, 2.5 m.s-1, and 3.0 m.s-1 and the experiment run times were 159 h, 134 h and 10 h, respectively. The average temperature (Tave) and relative humidity (RH) data for ua = 1.2 m.s-1 were 53{degrees}C and 7.31%, whilst for ua = 2.5 m.s-1, Tave was 56{degrees}C and RH = 7.19%, and for ua = 3.0 m.s-1, Tave was 63{degrees}C and RH = 6.16%. The experimental data was input into the four variable Penman-Monteith method to compute the evaporative demand (Ed). For each of the air velocities, the respective Ed values obtained were 0.16, 0.31 and 0.36 mm.d-1. The Bowen ratios (r) were well below 1 (r < 1), which suggested a sufficient supply of moisture to evaporate. For Ed = 0.16 mm.d-1 the vapour pressure deficit (VPD) was 113.08 mbars, whilst for Ed = 0.31 mm.d-1 and for Ed = 0.36 mm.d-1 the VPD were 129.93 mbars and 150.14 mbars, respectively. The recorded discharges (q) at t = 10 hrs for Ed= 0.16 mm.d-1 was 7.67*10-3 l.hr-1.m-1, whilst for Ed = 0.31 mm.d-1 q = 14.5*10-3 l.hr-1.m-1, and for Ed = 0.36 mm.d-1 q = 20.8*10-3 l.hr-1.m-1. The imposed negative pressure causes an exponential increase in moistube discharge, thus disproving the null hypothesis. The higher the evaporative demand the higher the discharge. This phenomenon allows moistube irrigation to be used for deficit irrigation purposes and allows irrigators to capitalize on realistic soil matric potential irrigation scheduling approach.

scientific communication and education