Browsing by Author "Tumbo, Madaka"

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    Analysis of spatial and temporal trend of hydro‑climatic parameters in the Kilombero River Catchment, Tanzania
    (Springer Nature Limited, 2023-05-15) Sigalla, Onesmo; Valimba, Patrick; Selemani, Juma; Kashaigili, Japhet; Tumbo, Madaka
    Inadequate knowledge on actual water availability, have raised social-economic conficts that necessitate proper water management. This requires a better understanding of spatial–temporal trends of hydro-climatic variables as the main contributor to available water for use by sectors of economy. The study has analysed the trend of hydro-climatic variables viz. precipitation, temperature, evapotranspiration and river discharge. One downstream river gauge station was used for discharge data whereas a total of 9 daily observed and 29 grided satellite stations were used for climate data. Climate Hazards Group InfraRed Precipitation was used for precipitation data and Observational Reanalysis Hybrid was used for Temperature data. Mann–Kendall Statistical test, Sen’s slope estimator and ArcMap Inverse Distance Weighted Interpolation functionality were employed for temporal, magnitude and spatial trend analysis respectively. Results confrmed that, spatially, there are three main climatic zones in the study area viz. Udzungwa escarpment, Kilombero valley and Mahenge escarpment. On temporal analysis, with exception of the declining potential evapotranspiration trend, all other variables are on increase. This is with catchment rates of 2.08 mm/year, 0.05 °C/year, 0.02 °C/year, 498.6 ­m3 /s/year and − 2.27 mm/year for precipitation, Tmax, Tmin, river discharge and PET respectively. Furthermore, rainfalls start late by a month (November) while temperatures picks earlier by September and October for Tmax and Tmin respectively. Water availability matches farming season. However, it is recommended to improve water resources management practices to limit fow impairment as expansions in sectors of economy are expected. Furthermore, landuse change analysis is recommended to ascertain actual trend and hence future water uptake.
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    Characterizing rainfall patterns and dynamics in the Little Ruaha catchment, southern Tanzania
    (Frontiers, 2025-10-06) Mahay, Florence; Mahay F.H.; Valimba, Patrick; Tumbo, Madaka; Izdori, Fides; Mwabumba, Mohamed
    Water resources in many regions are increasingly under pressure due to population growth, agricultural expansion, and climate variability, which presents significant challenges in maintaining sustainable water supplies. The Little Ruaha catchment in Tanzania, a critical area for irrigation, water supply, and hydropower projects, is similarly affected by these pressures. This study was conducted to examine in detail the spatial–temporal variability and trends of rainfall indices to inform sustainable water resource management within the catchment. The study utilized the Mann-Kendall (MK) statistical test at a 95% confidence level (p ≤ 0.05), to assess the onset and cessation of annual and seasonal rainfall trends, with a particular focus on the November to April (NDJFMA) rainfall season. Rainbow statistical software was employed to evaluate rainfall normality and probabilities at 20, 50, and 80% risk levels. Results show decreasing trends in annual rainfall at Kilima station and Iringa Maji but were significant at Kilima station. On the other hand, increasing trends which were not significant at Iringa met and Mafinga stations. In terms of seasonal rainfall, the Iringa Met and Kilima stations demonstrated decreasing trends which were significant at Kilima. In addition, Mafinga and Iringa maji stations exhibited insignificant increasing trend. The results indicate that rain-fed crops in the southern and northeastern regions of the catchment are highly susceptible to drought stress, particularly during the short rainfall season (20% probability). Furthermore, there is a significant risk of water stress for sensitive crops in a typical season (50% probability) in these areas. The study recommends the cultivation of short-cycle crops or the implementation of irrigation strategies in vulnerable locations, along with enhancing water productivity and enforcing water permit regulations to ensure sustainable downstream flows. These findings are crucial for hydrological planning, irrigation management, and the overall sustainability of water resources in the Little Ruaha catchment.