This study was conducted in the Hanumante River Basin, one of the major tributaries of the Bagmati River in central Nepal, which has experienced frequent urban flooding due to rapid urbanization and floodplain encroachment. The study aimed to develop flood hazard maps and assess the vulnerability of land use classes, buildings, and population under different flood return periods. Watershed delineation and hydrological analysis were performed using Shuttle Radar Topographic Mission Digital Elevation Model (SRTM-DEM), while flood inundation modelling was carried out using an integrated HEC-RAS, HEC-GeoRAS, and ArcGIS framework. Flood vulnerability was assessed through spatial overlay analysis of flood hazard maps with land use and OpenStreetMap building datasets and further verified through field observations. The results showed that flood extent and flood depth increased with increasing return periods. The simulated flood inundation area expanded from approximately 130 ha for the 2-year return period to 196 ha for the 100-year return period, while the maximum flood depth increased from 4.94 to 5.96 m. Validation against the July 2018 flood event indicated good agreement between simulated and observed flood conditions, with observed maximum flood depths of approximately 4.5 m and inundation widths of about 500 m compared to simulated values of 4.94 and 600 m, respectively. Agricultural land and residential areas were identified as the most vulnerable land use classes, and the number of exposed buildings increased from approximately 523 structures under the 2-year return period to 1747 structures under the 100-year return period. The generated flood hazard maps provide valuable information for floodplain management, urban planning, and disaster risk reduction in the rapidly urbanizing Hanumante River Basin.
Solar-thermal desalination provides a low-electricity pathway for decentralised freshwater production, while parabolic-trough collectors can supply concentrated thermal energy at temperatures suitable for evaporation. Reliable assessment, however, requires distinguishing experimentally recovered distillate from latent-heat-based production capacity. Existing compact trough systems have rarely integrated thermo-hydraulic characterisation, condensation measurements, product-water validation, and statistical optimisation within a single experimental framework. This investigation aims to quantify and optimise the experimentally validated desalination performance of a gravity-fed parabolic-trough system under outdoor operation. A 900-mm-aperture tracked collector with a black-coated copper receiver was fabricated, and synchronised irradiance, temperature, flow, evaporator, condenser, and distillate measurements were acquired during 300-min tests. HTF flow rate and inlet temperature were varied through response-surface experiments, while feed and distillate water quality were characterised. Experimental distillate production ranged from 8.231 to 10.362 mL min−1, and the highest-performing condition recovered 3.109 L. Collector and desalination thermal efficiencies reached 32.865 (R^2) values of 0.9520, 0.9442, and 0.9347 for the three responses. These results establish a quantitatively validated link between collector operation and recovered freshwater. Future renewable energy should integrate thermal storage, extended saline operation, and long-duration fouling assessment.
Constructed wetlands are increasingly recognized across Africa as sustainable, low-cost solutions for wastewater treatment, particularly in rural and peri-urban areas where conventional infrastructure remains unfeasible. However, evidence from the continent remains fragmented, limiting the generalizability of findings and hindering widespread adoption. This systematic review and meta-analysis synthesized available data on design characteristics and pollutant removal performance of constructed wetlands implemented in Africa. Following PRISMA 2020 guidelines, a comprehensive search of Scopus, Web of Science, PubMed, and Google Scholar (1990–2024) identified 370 references, of which 25 studies met eligibility criteria. Most systems were horizontal subsurface flow wetlands, though vertical flow and hybrid configurations were also common. Hydraulic loading rates ranged from 0.02 to 0.20 m3/m2·d, with surface areas of 2–10 m2 per population equivalent. Weighted average removal efficiencies reached 70–95
Climate variability threatens catchment-based urban water supply across sub-Saharan Africa. This study assessed long-term trends in key climate parameters, modelled historical and projected streamflow, and developed an integrated water-resource protection and management plan for the Little Ruaha Catchment, Tanzania. Rainfall and temperature records extending from 1964 to 2025 were analysed using the Mann–Kendall test and Sen’s slope estimator. Streamflow was simulated using the Soil and Water Assessment Tool (SWAT), with future simulations driven by bias-corrected Coupled Model Intercomparison Project Phase 6 (CMIP6) climate projections under moderate- and high-emission pathways. Structured interviews with 15 institutional respondents were analysed thematically and integrated with the hydroclimatic and modelling evidence. Rainfall trends were spatially differentiated, including a significant decline at Mafinga of 18.4 mm per decade, whereas all long-record temperature stations showed significant warming of 0.19–0.30 °C per decade. SWAT performance was evaluated at Makalala, Mawande and Ndiuka using a common calibration period (1996–2012) and independent validation period (2013–2024). Calibration NSE values ranged from 0.67 to 0.72 and validation NSE values from 0.63 to 0.68, with corresponding KGE values of 0.66–0.70 and 0.62–0.66. At Ndiuka, the mean annual number of days with streamflow below the study-specific 5 m3/s low-flow screening threshold increased from 35.8 days during 1994–2005 to 69.9 days during 2016–2025. Mean annual flow is projected to decline by 11–17
This study evaluates the wind energy potential and long-term variability trends at the Katsina Wind Farm, Northern Nigeria, over the period 2005–2021. Daily meteorological data, including wind speed and surface air temperature measured at 10 m height, were obtained from the Nigeria Meteorological Agency (NiMet). Data preprocessing involved quality control procedures, including outlier detection, homogeneity testing, and interpolation of missing values. Wind speeds were extrapolated to turbine hub height using the power law, and wind characteristics were modeled using the Weibull probability distribution function. Wind power density and extractable energy were computed using standard empirical formulations. Wind power generation potentials at Katsina Wind Farm since the start of the project in 2005 are yet to be well documented, therefore this research. Results indicate that mean monthly wind power density ranges from 59 ± 11 to 152 ± 22 W/m2, while mean energy output varies between 4.6 ± 0.5 and 5.1 ± 1.0 MWh. Trend analysis using linear regression and the Mann–Kendall test indicated increasing trends in temperature (0.4 °C/year) and wind speed (0.1 m/s/year). Weibull parameters (k ≈ 2–3; c ≈ 6–9 m/s) indicate moderate seasonal variability. Model validation using RMSE, MAE, and Nash–Sutcliffe Efficiency (NSE > 0.75) confirms good predictive performance. The findings demonstrate that the Katsina site has viable wind energy potential for sustainable power generation. However, integration with complementary renewable sources is recommended to enhance energy reliability.
