Browsing by Author "Kanda, Edwin K."

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  • Publication
    Publication
    Assessment of rainwater harvesting potential of Rachuonyo North Sub-Catchment in Kenya using the Australian water balance model
    (IWA, 2022-01-29) Odhiambo, Kevin O.; Ong'or, Basil T. Iro; Kanda, Edwin K.
    Rainwater harvesting (RWH) is emerging as a promising alternative source of water in sub-Saharan Africa. It can be an alternative source of good-quality water to substitute other freshwater sources, to enable crop production beyond the growing season through supplemental irrigation as well as to improve the environment by minimizing the effect of drought and floods. The Rachuonyo North Sub-County of Kenya experiences low rainfall coupled with high population with limited access to reliable water sources. The study assessed the RWH potential of the Rachuonyo North Sub-Catchment with the aim of providing information on alternative water resources to meet the water demands for agriculture as well as domestic use in the region. The Australian water balance model (AWBM) was used to simulate the RWH potential of the Rachuonyo North Sub-Catchment using the area rainfall, evapotranspiration and river flow data. The calibration and validation of the model were performed with calibration and validation results yielding Nash–Sutcliffe efficiency (NSE) values of 0.503 and 1.00, respectively. Research findings indicated that the area has a potential for RWH with runoff harvest of between 104,496 and 43,646,142 m3/month, which can significantly support the residential and irrigation water demands for the area. Policymakers and development agencies in the region should pro-actively put in place measures to promote RWH interventions as a tool for increasing access to water. The methodology in the study is suitable for adaption for rainfall–runoff simulation in other sub-Saharan African regions where data are limiting.
  • Publication
    Publication
    Coupling hydrological and crop models for improved agricultural water management a review
    (Bulgarian Journal of Agricultural Science, 2019-04-09) Kanda, Edwin K.; Mabhaudh, Tafadzwanashe; Senzanje, Aidan
    Understanding the relationships among plant, soil, and water is important in agricultural water management practices. Simulation of the soil water balance is central to improving crop water productivity. Individual crop or hydrological models have shortcomings due to the simplifi cation of the surface or subsurface processes. Coupling of crop and hydrological models helps in understanding the complex processes involved in crop production. This review highlights the application of coupled crop and hydrological models in simulation of crop response to water availability. The hydrological models considered are CHAIN-2D, HYDRUS-1D, HYDRUS 2D/3D, and MODFLOW. The crop growth models considered are the water-driven model (AquaCrop), solar-radiation driven model (EPIC), and the carbon-driven models (WOFOST and DSSAT). HYDRUS-2D is the successor to CHAIN-2D. MODFLOW is a popular model especially in simulating groundwater fl ow while HYDRUS is satisfactory in the simulation of water dynamics in the vadose zone. From the review, it can be deduced that HYDRUS-1D has been coupled with all the crop models considered except DSSAT. EPIC – CHAIN-2D and MODFLOW-DSSAT were the other applications. Further research needs to consider linking 2D soil water models with any of the crop growth models for a better representation of the soil water dynamics and therefore accurate simulation of the soil water balance.
  • Publication
    Publication
    Optimization of rainwater harvesting system design for smallholder irrigation farmers in Kenya
    (IWA Publishing, 2021-04-15) Odhiambo, Kevin O.; Iro Ong'or, Basil T.; Kanda, Edwin K.
    The adverse effects of climate change on agriculture have been felt across the globe. Smallholder farmers in sub-Sahara Africa are particularly more vulnerable to the effects of climate change leading to loss of income and livelihood thus affecting global food security. Rainwater harvesting (RWH) is emerging as a viable option to mitigate the negative effects of climate change by supporting rain-fed agriculture through supplemental irrigation. However, smallholder farmers are still grappling with a myriad of challenges hindering them from reaping the benefits of their investment in RWH systems. This review explores some of the factors behind the poor performance of RWH systems in Kenya and also seeks to suggest techniques that can be applied to optimize the design parameters for improved performance and the adoption of RWH systems. According to the review, RWH has the potential to mitigate the adverse effects of climate change among smallholder farmers. It allows for crop production beyond the growing season through supplemental irrigation. However, their impacts have been minimal due to the consistent poor performance of RWH systems. This is attributed to inefficiencies in design and construction brought about by lack of required technical skills among RWH system designers and implementers. Proper design and implementation are therefore paramount for better performance and adoption of RWH systems in the region. This will ensure that RWH systems are reliable, technically and economically feasible as well as possess a desirable water-saving efficiency.