Future Climate Change Impacts on River Discharge Seasonality for Selected West African River Basins

The changing climate is a concern to sustainable water resources. This study examined climate change impacts on river discharge seasonality in two West African river basins; the Niger river basin and the Hadejia-Jama’are Komadugu-Yobe Basin (HJKYB). The basins have their gauges located within Nigeria and cover the major climatic settings. Here, we set up and validated the hyper resolution global hydrological model PCR-GLOBWB for these rivers. Time series plots as well five performance evaluation metrics such as Kling–Gupta efficiency (KGE),); the ratio of RMSE-observations standard deviation (RSR); per cent bias (PBIAS); the Nash–Sutcliffe Efficiency criteria (NSE); and, the coefficient of determination (r2), were employed to verify the PCR-GLOBWB simulation capability. The validation results showed from satisfactory to very good on individual rivers as specified by PBIAS (−25 to 0.8), NSE (from 0.6 to 0.8), RSR (from 0.62 to 0.4), r2 (from 0.62 to 0.88), and KGE (from 0.69 to 0.88) respectively. The impact assessment was performed by driving the model with climate projections from five global climate models for the representative concentration pathways (RCPs) 4.5 and 8.5. We examined the median and range of expected changes in seasonal discharge in the far future (2070–2099). Our results show that the impacts of climate change cause a reduction in discharge volume at the beginning of the high flow period and an increase in discharge towards the ending of the high flow period relative to the historical period across the selected rivers. In the Niger river basin, at the Lokoja gauge, projected decreases added up to 512 m3/s under RCP 4.5 (June to July) and 3652 m3/s under RCP 8.5 (June to August). The three chosen gauges at the HJKYB also showed similar impacts. At the Gashua gauge, discharge volume increased by 371 m3/s (RCP8.5) and 191 m3/s (RCP4.5) from August to November. At the Bunga gauge, a reduction/increase of -91 m3/s/+84 m3/s (RCP 8.5) and -40 m3/s/+31 m3/s/(RCP 4.5) from June to July/August to October was simulated. While at the Wudil gauge, a reduction/increase in discharge volumes of −39/+133 m3/s (RCP8.5) and −40/133 m3/s (RCP 4.5) from June to August/September to December is projected. This decrease is explained by a delayed start of the rainy season. In all four rivers, projected river discharge seasonality is amplified under the high-end emission scenario (RCP8.5). This finding supports the potential advantages of reduced greenhouse gas emissions for the seasonal river discharge regime. Our study is anticipated to provide useful information to policymakers and river basin development authorities, leading to improved water management schemes within the context of changing climate and increasing need for agricultural expansion

Prevalence, intensity, and exposed variables of infection with Acanthocephala parasites of the gastrointestinal tract of Coptodon zillii (Gervais, 1848) [Perciformes: Cichlidae] in Zobe Dam, Dutsin-Ma Local Government Area, Katsina State, Nigeria

Abstract Background Estimate shows that about one billion people rely on fish as primary source of animal protein. Currently, the global record portraying Nigeria as the largest producer of fishes (over 15,489 t per annum) in Africa is being threatened by the presence of various species of parasites that consider fishes as suitable definitive hosts. Control strategies will, however, be ineffective if there are scanty epidemiological data. Based on this premise, we undertook this present study to identify species of parasites, their prevalence, mean intensities, and indicators of infection of Coptodon zillii in Zobe Dam in the study area. Methodology Study design was cross-sectional in nature with sample size of 411 fish. The data collected from this study were entered into Microsoft Excel 2010 and analyzed with Epi Info™ 7. After evisceration and standard histological protocol, recovered parasites were identified as Acanthogyrus tilapiae using standard identification keys. Results Major findings of this study show that the overall prevalence and mean intensity of piscine acanthocephaliasis were 16.30% (12.94–20.31) and 1.46 (1.19–1.72) parasites per Coptodon zillii respectively. Prevalence and mean intensity of Acanthocephala infection significantly increased as the length of fish increased (χ 2 = 14.001; p = 0.0002) with fish having a length range of 17.0–23.9 cm being about four times more likely to be infected compared to those with 11.0–16.9 cm length [COR (95% CI) 3.78(1.81–7.89)]. In like manner, there was a significant increase in the prevalence of infection as the weight of fish increased (χ 2 = 6.055; p = 0.0139) with those belonging to weight category 190.1–250.0 g being three times more likely to be infected compared to those in 70.1–130.0 g category [COR (95% CI) 3.38 (1.05–10.84)]. Besides, Fulton’s condition factor was a major determinant of infection with piscine acanthocephaliasis (χ 2 = 13.981; p = 0.0002). Conclusion Based on the findings of this study, it could be concluded that length, weight, and condition factor were indicators which contributed substantially to piscine acanthocephaliasis in Zobe Dam. In view of reports indicting acanthocephalans as biomarkers of lead (Pb) pollution, further study is, however, recommended to ascertain this hypothesized heavy metal pollution in the study area and its environs

GIS-Based Sub-Basin Scale Identification of Dominant Runoff Processes for Soil and Water Management in Anambra Area of Nigeria

Identifying landscapes having comparable hydrological characteristics is valuable for the determination of dominant runoff process (DRP) and prediction of flood. Several approaches used for DRP-mapping vary in relation to data and time requirement. Manual approaches which are based on field investigation and expert knowledge are time demanding and difficult to implement at regional scale. Automatic GIS-based approach on the other hand require simplification of data but is easier to implement and it is applicable on a regional scale