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Characterisation of Hydrological Drought and Implications for Sustainable Water Resources Management in the Sokoto-Rima River Basin (SRRB), Nigeria

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Open Journal of Modern Hydrology 2020年第3期10卷 65-79页

作者： martins yusuf otache Onemayin David Jimoh John Jiya Musa Abdullahi Danmagaji Department of Agricultural & Bioresources Engineering Federal University of Technology Minna Nigeria Department of Civil Engineering Federal University of Technology Minna Nigeria Sokoto-Rima River Basin Development Authority Sokoto Nigeria

Hydrological drought is usually characterised by water loss over time from both underground and surface supplies. Thus for this study, the assessment of hydrological drought was carried out by employing Cumulative Rainfall/Streamflow Anomaly as preliminary tools for the presence of drought signatures while detailed characterisation was via Streamflow Drought Index (SDI). The results revealed that hydrological drought was observed in all the stations;however, though in general, the stations could be classified as experiencing near normal drought conditions with mild drought signatures. The findings also revealed that the average streamflow deficit volume and durations of the hydrological drought severity were 1.780 Mm3 and 192 months, 1.444 Mm3 and 252 months, 3.148 Mm3 and 252 months, and 0.159 Mm3 and 372 months for Bakolori, Goronyo (pre dam construction era), Goronyo (post dam construction era) and Zobe stations, respectively. The results also revealed the relevance of flow duration curve and analysis of frequency of drought state transition for the development of scenario-based basin water resources management protocol. The coefficient of determination (R2) statistic of the developed regression models indicate that 73.3% and 86.5% variation in streamflow dynamics across the Basin can be explained by climate change variables. However, for sustainable management of water resources in the Basin, it is imperative that characterisation of hydr

关键词： Hydrological Drought Water Resources Sustainability Management Climate Change

Application of Parametric-Based Framework for Regionalisation of Flow Duration Curves

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Journal of Geoscience and Environment Protection 2016年第5期4卷 89-99页

作者： martins yusuf otache Muhammad Abdullahi Tyabo Iyanda Murtala Animashaun Lydia Pam Ezekiel Department of Agricultural & Bioresources Engineering Federal University of Technology Minna Nigeria Department of Technical Education Niger State College of Education Minna Nigeria

It is common knowledge that the end user of stream flow data may necessarily not have any prior knowledge of the quality control measures applied in their generation, therefore, conclusions drawn most often times may not be effective as desired. Thus, this study is an attempt at providing an independent quality construct to boost the confidence in the use of stream flow data by developing regional flow duration curves for selected ungauged stations of the upper Niger River Basin, Nigeria. Toward this end, stream flow data for seven gauging stations cover some sub basins in the Basin were obtained;precisely, monthly stream flow data covering a range of eleven to fifty-three years period. The flow duration curves from the gauging stations were fitted with three probability distribution models;i.e., logarithmic, power and exponential regression models. For the regionalisation, parameterisation was carried out in terms of the drainage area alone to allow for simplicity of models. Results obtained showed that the exponential regression model, in terms of Coefficient of Determination (R2) had the best fit. Though the regionalised model was simple, measurable agreement was obtained during the calibration and validation phases. However, considering the length of data used and probable variability in the stream flow regime, it is not possible to objectively generalise on the quality of the results. Against this backdrop, it suffices to take into cognisance the need to use an ensemble of catchment characteristics in the development of the flow duration curves and the overall regional models;this is important considering the implications of anthropogenic activities and hydro-climatic variations.

关键词： Regionalisation Parametric Models Anthropogenic Hydro-Climatic Variations

Conditional Heteroscedasticity in Streamflow Process: Paradox or Reality?

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Open Journal of Modern Hydrology 2012年第4期2卷 79-90页

作者： martins yusuf otache Isiguzo Edwin Ahaneku Abubakar Sadeeq Mohammed John Jiya Musa Department of Agricultural & Bioresources Engineering Federal University of Technology Minna Nigeria

The various physical mechanisms governing the dynamics of streamflow processes act on a seemingly wide range of temporal and spatial scales;almost all the mechanisms involved present some degree of nonlinearity. Against the backdrop of these issues, in this paper, attempt was made to critically look at the subject of Autoregressive Conditional Heteroscedasticity (ARCH) or volatility of streamflow processes, a form of nonlinear phenomena. Towards this end, streamflow data (both daily and monthly) of the River Benue, Nigeria were used for the study. Results obtained from the analyses indicate that the existence of conditional heteroscedasticity in streamflow processes is no paradox. Too, ARCH effect is caused by seasonal variation in the variance for monthly flows and could partly explain same in the daily streamflow. It was also evident that the traditional seasonal Autoregressive Moving Average (ARMA) models are inadequate in describing ARCH effect in daily streamflow process though, robust for monthly streamflow;and can be removed if proper deseasonalisation pre-processing was done. Considering the findings, the potential for a hybrid Autoregressive Moving Average (ARMA) and Generalised Autoregressive Conditional Heteroscedasticity (GARCH)type models should be further explored and probably embraced for modelling daily streamflow regime in view of the relevance of statistical modelling in hydrology.

关键词： Autoregressive Heteroscedasticity Homoscedasticity Volatility Nonlinear Dynamics

Effects of Model Structural Complexity and Data Pre-Processing on Artificial Neural Network (ANN) Forecast Performance for Hydrological Process Modelling

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Open Journal of Modern Hydrology 2021年第1期11卷 1-18页

作者： martins yusuf otache John Jiya Musa Ibrahim Abayomi Kuti Mustapha Mohammed Lydia Ezekiel Pam Department of Agricultural & Bioresources Engineering Federal University of Technology Minna Nigeria Raw Materials Research and Development Council Abuja Nigeria

The choice of a particular Artificial Neural Network (ANN) structure is a seemingly difficult task;worthy of relevance is that there is no systematic way for establishing a suitable architecture. In view of this, the study looked at the effects of ANN structural complexity and data pre-processing regime on its forecast performance. To address this aim, two ANN structural configurations: 1) Single-hidden layer, and 2) Double-hidden layer feed-forward back propagation network were employed. Results obtained revealed generally that: a) ANN comprised of double hidden layers tends to be less robust and converges with less accuracy than its single-hidden layer counterpart under identical situations;b) for a univariate time series, phase-space reconstruction using embedding dimension which is based on dynamical systems theory is an effective way for determining the appropriate number of ANN input neurons, and c) data pre-processing via the scaling approach excessively limits the output range of the transfer function. In specific terms considering extreme flow prediction capability on the basis of effective correlation: Percent maximum and minimum correlation coefficient (Rmax% and R

关键词： Streamflow Neural Network Phase-Space Optimisation Algorithm

Characterisation of Meteorological Drought in Northern Nigeria Using Comparative Rainfall-Based Drought Metrics

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Journal of Water Resource and Protection 2023年第2期15卷 51-70页

作者： Onemayin David Jimoh martins yusuf otache Adeolu Richard Adesiji Rotimi Saka Olaleye James Agajo Department of Civil Engineering Federal University of Technology Minna Nigeria Department of Agricultural & Bioresources Engineering Federal University of Technology Minna Nigeria Department of Agricultural Economics & Farm Management Federal University of Technology Minna Nigeria Department of Computer Engineering Federal University of Technology Minna Nigeria

Meteorological droughts occur when there is deficiency in rainfall;i.e. rainfall availability is below some acclaimed normal values. Hence, the greater challenge is to be able to obtain suitable methods for assessing drought occurrence, its onset or initiation and termination. Thus, an attempt was made in this paper to evaluate the performance of Standardised Precipitation Index (SPI) and Standardised Precipitation Anomaly Index (SPAI) to characterise drought in Northern Nigeria for purposes of comparison and eventual adoption of probable candidate index for the development of an Early Warning System. The findings indicated that despite the fact that the annual timescale may be long, it can be employed to obtain information on the temporal evolution of drought especially, regional behaviour. However, monthly timescale can be more appropriate if emphasis is on evaluating the effects of drought in situations relating to water supply, agriculture and groundwater abstractions. The SPAI can be employed for periodic rainfall time series though;it accentuates drought signatures and may not necessarily dampen high fluctuations due to implications of high climatic variability considering the stochastic nature and state transition of drought phenomena. On the other hand, the temporal evolution of SPI and SPAI were not coherent at different temporal accumulations with differences in fluctuations. However, despite the differences between the SPI and SPAI, generally at some timescales, for instance, 6-month accumulation, both spatial and temporal distributions of drought characteristics were seemingly consistent. In view of the observed shortcomings of both indices, especially the SPI, the Standardised Nonstationary Precipitation Index (SnsPI) should be looked into and too, other indexes that take into consideration the implications of global warming by incorporating potential evapotranspiration may be deemed more suitable for drought studies in Northern Nigeria.

关键词： Characterisation Timescale Meteorological Drought Metrics

Spatiotemporal Variation of Land Use Pattern and Land Cover Changes in Gidan Kwano Watershed Area in North Central Nigeria

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Open Journal of Ecology 2022年第5期12卷 271-286页

作者： Isa Hassan Musa John Jiya Musa martins yusuf otache Ayodele Joshua Odofin Ayodele Joshua Odofin Ebierni Akpoebidimiyen Otuaro Department of Agricultural and Bioresources Engineering Federal University of Technology Minna Nigeria Department of Soil Sciences and Land Management Federal University of Technology Minna Nigeria Department of Civil Engineering Maritime University Okerenkoko Delta State Nigeria

Land Management Systems (LMS) are institutional frameworks complex by the tasks they must achieve, national, cultural, political, and judicial settings and technology. The urbanisation process in Nigeria has increased since the 1960s because of the crude oil boom era and other government-backed industrial initiatives and investments. This study employed the use of both primary and secondary sources of data. Preliminary data comprise methods of land use, types of agricultural activities carried out and the process of working on the land by the farmers within a 10 km radius. The secondary data involved the interactive digital and visual techniques of the Geographical Information system for five seasons, with each having a ten-year interval span within 1975 to 2015. Statistical analysis was carried out with SPSS 2013 and XLSTAT 2015. Five land use and land cover types were observed within the Gidan Kwano watershed, which includes wetlands (WL), water bodies (WB), bare grounds (BG), vegetation (VG), and settlements (SL). The most prevalent landform in the study area during the 1975 period was the vegetative area which was 50% of the total landmass. Thus, the vegetation (VG) covered half of the Gidan Kwano watershed. However, the vegetative area decreased substantially during the study period of 1975 to 2015. It was observed that the vegetation (VG) within the study area had the highest percentage of coverage, of 34%. During the study period, a significant decrease was observed in the WL, WB and VG areas. It was also concluded that due to the built-up places, the infiltration of surface runoff from rainwater would be drastically reduced as most of the sections are paved for construction activities while a section of the study area is covered with rock outcrops and farmlands.

关键词： Agriculture Bare Land Land Use Settlement Vegetation and Wetland

Analysis of stochastic characteristics of the Benue River flow process

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Chinese Journal of Oceanology and Limnology 2008年第2期26卷 142-151页

作者： martins Y. otache Mohammad BAKIR 李致家 State Key Laboratory of Hydrology-Water Resources ＆ Hydraulic Engineering Hohai University Nanjing 210098 China

Stochastic characteristics of the Benue River streamflow process are examined under conditions of data austerity. The streamflow process is investigated for trend, non-stationarity and seasonality for a time period of 26 years. Results of trend analyses with Mann-Kendall test show that there is no trend in the annual mean discharges. Monthly flow series examined with seasonal Kendall test indicate the presence of positive change in the trend for some months, especially the months of August, January, and February. For the stationarity test, daily and monthly flow series appear to be stationary whereas at 1%, 5%, and 10% significant levels, the stationarity alternative hypothesis is rejected for the annual flow series. Though monthly flow appears to be stationary going by this test, because of high seasonality, it could be said to exhibit periodic stationarity based on the seasonality analysis. The following conclusions are drawn：（1） There is seasonality in both the mean and variance with unimodal distribution. （2） Days with high mean also have high variance. （3） Skewness coefficients for the months within the dry season period are greater than those of the wet season period, and seasonal autocorrelations for streamflow during dry season are generally larger than those of the wet season. Precisely, they are significantly different for most of the months. （4） The autocorrelation functions estimated ＂over time＂ are greater in the absolute value for data that have not been deseasonalised but were initially normalised by logarithmic transformation only, while autocorrelation functions for i = 1, 2 365 estimated ＂over realisations＂ have their coefficients significantly different from other coefficients.

关键词： trend stationarity seasonality over time over realisation stochastic skewness

Analysis of long-term dependence phenomenon in Benue River flow process and its hypothesis testing

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Chinese Journal of Oceanology and Limnology 2008年第3期26卷 313-322页

作者： martins Y. otache 李致家 Mohammad BAKIR State Key Laboratory of Hydrology-Water Resources ＆ Hydraulic Engineering Hohai University Nanjing 210098 China

In this paper, the long-term dependence phenomenon （the Hurst Effect） which characterizes hydrological and other geophysical times series is studied. The long-term memory is analysed for both daily and monthly streamflow series of the Benue River at Makurdi, Nigeria by using heuristic methods and testing specifically the null hypothesis of short-term memory in the monthly flow series. Results obtained by applying heuristic procedures indicated that there may be the presence of long-term memory component in mean daily flow series but there is no discernible reason to suspect the presence in both average monthly and maximum monthly flow series （extreme event）. Hypothesis testing was conducted by using original and modified versions of rescaled range statistic. When the modified rescaled range, which accounts for short-term memory in the series, is used, the null hypothesis is accepted for both the average monthly and maximum monthly flow series, indicating little or no probable presence of long-term memory in the series. An identical conclusion is also arrived at when second null hypothesis for independence of the monthly flow series is tested. Therefore, apart from the mean daily flow series, there is little evidence of long-term dependence in the Benue River streamflow series at Makurdi. However, considering the limited length of data used, the results are inconclusive.

关键词： Hurst exponent hydrological method time series river flow long memory Nigeria

Achieving low effluent NO_3-N and TN concentrations in low influent chemical oxygen demand(COD) to total Kjeldahl nitrogen(TKN) ratio without using external carbon source

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Chinese Journal of Oceanology and Limnology 2015年第4期33卷 1039-1052页

作者：操家顺 OLEYIBLO Oloche James 薛朝霞 otache Y.martins 冯骞 Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education College of Environment Hohai University College of Environment Hohai University National Engineering Research Center of Water Resource Efficient Utilization and Engineering Safety Hohai University Department of Agricultural & Bioresources Engineering Federal University of Technology

Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal(BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic(A2 /O). The ASM2 d implemented on the platform of WEST2011 software and the Bio Win activated sludge/anaerobic digestion(AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2 d parameters(the reduction factor for denitrification(η NO3, H), the maximum growth rate of heterotrophs( μ H), the rate constant for stored polyphosphates in PAOs(q pp), and the hydrolysis rate constant(k h)) were adjusted. Whereas three Bio Win parameters(aerobic decay rate(b H), heterotrophic dissolved oxygen(DO) half saturation(K OA), and Y P /acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations(ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen(N-NO3), total nitrogen(TN), and total phosphorus(TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand(COD) to total Kjeldahl nitrogen(TKN) ratio(COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.

关键词： anaerobic anoxic oxic (A2/O) process activated sludge ASM2d BioWin AS/AD WEST2011