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Atmospheric and Climate Sciences 2014年第5期4卷 941-955页

作者： Bakary Bamba Abé Delfin Ochou Eric-Pascal Zahiri modeste kacou Laboratory of Atmospheric Physics and Fluid Mechanics University Félix Houphouet-Boigny Abidjan Cote d’Ivoire Geosciences Environment Toulouse (GET) University Paul Sabatier of Toulouse III Toulouse France

Data from rain Drop Size Distributions gathered on five sites in Africa as well as those of the pilot site in Kourou (French Guyana, South America), located in different climatic zones, and collected by two types of disdrometer (the impact JW RD-69 disdrometer and the Optical Spectro-Pluviometer, OSP) are used to study the consistency of the reflectivity factor-rain rate at the ground (Z-R) relationship variability. The results clearly confirm that the relationship Z-R knows a large spatial variability, from a type of precipitation to another and within the same precipitation regardless the type of disdrometer used for DSD measurements. Base on the similarity of the relations reflectivity factor-rain rate and ratio median volume diameter over the total number of drops-rain rate, the variability of the Z-R coefficients (A, b) through the simultaneously implication of the size and number of drops which characterize the DSD was exhibited. It was shown that the relationships A-α and b-β designed to understand the involvement of parameters D0 and NT of DSD in the variability of the relationship Z-R are similar regardless the types of disdrometer used. However, the relations A-α in the Sahelian region appear to deviate from those of Guinean, equatorial and Soudanian zones. The plausible reasons were discussed.

关键词： Drop Size Distributions Consistency in Z-R Relationship Variability Squall Lines Thunderstorm Stratiform Rain JW RD-69 Disdrometer Optical Spectro-Pluviometer OSP

Diagnosis of the Causes of the Rain Flooding in June in the West Africa Coastal Area

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Atmospheric and Climate Sciences 2021年第1期11卷 11-31页

作者： Joël Amouin Kouassi Yves Kouadio modeste kacou Sandrine Djakouré Samuel Ta Laboratory of Matter Environmental and Solar Energy Sciences (LASMES) Ocean-Atmosphere Interaction Group University F.H.B. of Cocody Abidjan Abidjan C&ocirc te d’Ivoire Abidjan Meteorological Center of the Agency for the Safety of Air Navigation in Africa and Madagascar (ASECNA) Abidjan C&ocirc te d’Ivoire

Rain flooding during June on the West Africa coastal area is analyzed by using the 95th and 75th percentiles, which represent extreme and intense rainfall events respectively. Thus, the contribution of these events that reaches around 50% shows their impact on the rainfall in June. Atmospheric and oceanic factors influence the rain flooding. Indeed, the extreme events are associated with easterly waves propagating from 20°E, while those of intense events are initiated around 5°E. The impact of oceanic conditions exhibits the warming of the equatorial rail and the Atlantic cold tongue, the warming of the whole ocean basin and a north-south dipole of SST anomalies. The West African monsoon that reaches Abidjan corresponds to a low-level atmospheric flow, whose upward motion extends in latitude from the ocean to the continent. An increase of disturbance contributes to enhancing these events. This is confirmed by the inflow on to the continent of oceanic moisture coming from the ventilation by evaporation of warm water. In addition, the coupled ocean-atmosphere simulations are one of the best candidates that could help to better explain these dramatic events. This study is useful because of showing solutions that could help in adoption of policies for the risks management related to these events.

关键词： West Africa Coast Rain Flooding Threshold Atmospheric and Ocean Surface Conditions

Improving Radar Rainfall Estimation by Accounting for Microphysical Processes Using a Micro Rain Radar in West Africa

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Atmospheric and Climate Sciences 2021年第4期11卷 658-688页

作者： Ghislain Kouadio Eric-Pascal Zahiri modeste kacou Augustin Kadjo Koffi Abé Delfin Ochou Paul Assamoi Laboratoire de Physique de l’Atmosphère et de Mécanique des Fluides (LAPA-MF) UFR SSMT Université Félix Houphou&#235 t-Boigny Abidjan C&#244 te d’Ivoire

This study evaluates the improvement of the radar Quantitative Precipitation Estimation (QPE) by involving microphysical processes in the determination of Z-R algorithms. Within the framework of the AMMA campaign, measurements of an X-band radar (Xport), a vertical pointing Micro Rain Radar (MRR) to investigate microphysical processes and a dense network of rain gauges deployed in Northern Benin (West Africa) in 2006 and 2007 were used as support to establish such estimators and evaluate their performance compared to other estimators in the literature. By carefully considering and correcting MRR attenuation and calibration issues, the Z-R estimator developed with the contribution of microphysical processes and non-linear least-squares adjustment proves to be more efficient for quantitative rainfall estimation and produces the best statistic scores than other optimal Z-R algorithms in the literature. We also find that it gives results comparable to some polarimetric algorithms including microphysical information through DSD integrated parameter retrievals.

关键词： Drop Distribution Micro Rain Radar Calibration Microphysical Processes Z-R Relationships Rainfall Estimation

Asymptotic Analysis of a Stochastic Model of Mosquito-Borne Disease with the Use of Insecticides and Bet Nets

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Journal of Applied Mathematics and Physics 2024年第1期12卷 305-329页

作者： Boubacar Sidiki Kouyaté modeste N’zi Department of Mathematics and Computer Science University of Science Technical and Technologies of Bamako Bamako Mali Laboratory of Applied Mathematics and Computer Science University Felix Houphouet-Boigny Abidjan C&#244te d’Ivoire

Ross’ epidemic model describing the transmission of malaria uses two classes of infection, one for humans and one for mosquitoes. This paper presents a stochastic extension of a deterministic vector-borne epidemic model based only on the class of human infectious. The consistency of the model is established by proving that the stochastic delay differential equation describing the model has a unique positive global solution. The extinction of the disease is studied through the analysis of the stability of the disease-free equilibrium state and the persistence of the model. Finally, we introduce some numerical simulations to illustrate the obtained results.

关键词： Vector-Borne Disease Epidemic Model Stochastic Delay Differential Equations Stochastic Stability Lyapunov Functional Technique

Stability of a Delayed Stochastic Epidemic COVID-19 Model with Vaccination and with Differential Susceptibility

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Journal of Applied Mathematics and Physics 2024年第2期12卷 509-532页

作者： modeste N’zi Boubacar Sidiki Kouyaté Ilimidi Yattara Modibo Diarra Laboratory of Applied Mathematics and Computer Science University Felix Houphouet-Boigny Abidjan C&#244te d’Ivoire Department of Mathematics and Computer Science University of Science Technic and Technologies Bamako Mali

In this paper, we treat the spread of COVID-19 using a delayed stochastic SVIRS (Susceptible, Infected, Recovered, Susceptible) epidemic model with a general incidence rate and differential susceptibility. We start with a deterministic model, then add random perturbations on the contact rate using white noise to obtain a stochastic model. We first show that the delayed stochastic differential equation that describes the model has a unique global positive solution for any positive initial value. Under the condition R0 ≤ 1, we prove the almost sure asymptotic stability of the disease-free equilibrium of the model.

关键词： SIRS Delayed Epidemic Model Nonlinear Incidence rate Lyapunov Function Asymptotic Stability in Probability

Evaluation of Agricultural Contamination Level by Heavy Metals and Pesticides in Sediments of Rivers and Water Bodies for Shrimp Fishing in the Lower Ouémé: Case of the Aguigadji, Ahlan and Sele Stations in Benin

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Advances in Materials Physics and Chemistry 2024年第2期14卷 25-46页

作者： Souradjou Orou Goura Fadéby modeste Gouissi Armelle Sabine Yélignan Hounkpatin Wakili Bolatito Yessoufou Tayéwo Sylvain Biaou Nonvignon Martial Fassinou Laboratory of Ecology Health and Animal Production (LESPA) Faculty of Agronomy (FA) University of Parakou (UP) Parakou Bénin Pluridisciplanary Research Laboratory for Technical Education (LARPET) University of Sciences Technologies Engineering and Mathematics of Abomey (UNSTIM) Lokossa Bénin

This study assessed sediment contamination by heavy metals and pesticide active ingredients linked to chemical inputs used in agricultural activities in the lower Ouémé. Pesticide residues from the organochlorine, pyrethroid and organophosphorus families were investigated by gas chromatography, and heavy metals (Cd, Pb, As, Ni, Zn, Fe, Mg, Cr and Hg) by atomic absorption spectrophotometry. The metallic pollution indices, the contamination factor (CF) and the ecological risk index were calculated. The results revealed 8 active ingredients in the rainy season and 9 in the dry season. Glyphosate was the active ingredient with the highest concentration at all stations, 9.65 ± 0.84 mg/kg recorded in the dry season at the Aguigadji station. All glyphosate values were above the EQS. DDT, Atrazine and Endosulfan also showed high concentrations in the dry and rainy seasons. Emamectin, Abamectin and Lambda Cyhalothrin also showed high concentrations in the dry season at Aguigadji, Ahlan and Sele. Only glyphosate was recorded at the control station (Toho), but in very low concentrations. Lead showed the highest concentrations at all the stations, 265.96 ± 21.02 mg/Kg in the rainy season and 255.38 ± 79.09 mg/Kg in the dry season, all detected at the Aguigadji station and above the EQS. Zn, Ni, Fe, Cu and Cr were all representative in both the dry and rainy seasons at the contaminated stations. Manganese showed high concentrations in the rainy season. Pb showed very high contamination (FC ≥ 6) at the Aguigadji and Ahlan stations and significant contamination (3 ≤ FC 6) at the Sele station in both the rainy and dry seasons. Ni, Hg and Cd, showed either moderate or significant contamination at the contaminated stations. The risk values showed a considerable ecological Ri (190 ≤ Ri < 380) in the rainy season and a moderate ecological Ri (95 ≤ Ri < 190) in the dry season at these contaminated stations.

关键词： Pesticides Heavy Metals Sediments Shrimp Fishing Area Lower Ouémé

Impact of Dewatering on the Spatio-Temporal Distribution of Benthic Macroinvertebrate Communities in the Okpara River, Benin

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Journal of Geoscience and Environment Protection 2024年第2期12卷 30-43页

作者： Sylvain Tayéwo Biaou Fadéby modeste Gouissi Armelle Sabine Yélignan Hounkpatin Zoulkanerou Orou Piami Wakili Bolatito Yessoufou Souradjou Orou Goura Nonvignon Martial Fassinou Laboratory of Ecology Health and Animal Production (LESPA) Faculty of Agronomy (FA) University of Parakou (UP) Parakou Benin Pluridisciplanary Research Laboratory for Technical Education (LARPET) University of Sciences Technologies Engineering and Mathematics of Abomey (UNSTIM) Lokossa Benin

Surface watercourses are areas of very high ecological and heritage value. Macroinvertebrates are bioindicators of the health of aquatic ecosystems. The aim of this study was to assess the effects of dewatering and re-watering cycles on benthic macroinvertebrate (BMI) communities. Two data collections were carried out at two stations (Okpara 1 and Okpara 2) on the Okpara river before and after dewatering. Thus, 8 samples of benthic macroinvertebrates and 12 physico-chemical parameters (T°C, pH, Transparency, Depth, Conductivity, Dissolved Oxygen that were measured in situ, and BOD5, COD, NH4+, NO3-, NO2- and PO43-) were assayed in the laboratory. Canonical Correspondence Analysis (CCA) was used to match physico-chemical data to MIB families. Shannon and Piélou diversity indices were used to determine the effects of dewatering on MIBs. The increase in temperature values of pH, BOD5, COD, NH4+, NO3-, NO2- and PO43-, after re-watering indicates the effect of dewatering on the quality of Okpara aquatic ecosystems. The benthic macrofauna collected consisted of 62.42% insects, 0.65% crustaceans, 6.48% molluscs, 0.72% worms and 0.14% arachnids. Whereas after re-watering, 21.67% insects, 0% crustaceans, 0.22% molluscs, 7.56% worms and 0.29% arachnids were recorded. Insects, crustaceans and molluscs were more abundant before dewatering than after. This was revealed by low abundances and taxonomic richness, as well as low Shannon index values of samples collected after re-watering.

关键词： Dewatering Benthic Macroinvertebrates Impact Physico-Chemical Parameters Okpara Rivers Nord-Benin

Granulometric and Mineralogical Characterization of the Sands of the Middle Course of the Kasai River (Territory of Ilebo, Province of Kasai/DR Congo)

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Journal of Geoscience and Environment Protection 2024年第7期12卷 50-71页

作者： Lowny Trésor Madienga Kitshabi Ivon Ndala Tshiwisa modeste Kisangala Muke Thomas Kanika Mamena Dominique Wetshondo Osomba Emmanuel Cibambula Musau Adalbert-Jules Makutu Ma Ngwayaya Department of Petroleum Exploration and Production Faculty of Oil Gas and Renewable Energies University of Kinshasa Kinshasa Democratic Republic of the Congo Department of Geosciences Faculty of Sciences and Technologies University of Kinshasa Kinshasa Democratic Republic of the Congo

The sand bars, in perpetual transformation, observable in the middle course of the Kasai river on the section between the city of Ilebo (pk605) to the confluence of the Loange river (pk525), pose enormous navigability problems. This may be dependent on hydrosedimentological characteristics of the Kasai River. This abundance of sand thus conditions the morphology of the middle course of the Kasai River in the section under our study. It therefore constitutes sedimentary navigation obstacles. The objective of this study is the granulometric and mineralogical characterization of the bar sands of the Kasai River in this study section. Particle size analyzes reveal these are moderately well classified to well classified unimodal sands (Classification coefficient between 1.29 to 1.742) largely presenting grain size symmetry and rarely fine asymmetry (Asymmetry coefficient—Skewness between −0.197 to 0.069) with mesorkurtic and rarely leptokurtic and platykurtic acuity (Angulosity coefficient—Kurtosis between 0.814 to 1.323). All these parameters evolve in sawtooth patterns from upstream to downstream. And then, an automated mineralogical analysis of the sands of the Kasaï River using a Qemscan FEG Quanta 650 made it possible to determine a very varied mineralogical procession with a sawtooth evolution. It is largely dominated by quartz (between 93.73% and 99.07%), followed by calcite (0.01% - 2.66%), iron oxides (0.01% - 1.88%), orthoclase (0.04% - 0.99%), plagioclase (0.01% - 0.75%) and Kaolinite (0.18% - 0.71%). Finally, this mineralogical procession is characterized by a group of minerals which do not reach the threshold of 0.55% such as: illite, apatite, ilmenite, muscovite, chlorite, biotite, montmorillonite, rutile, pyrophyllite, siderite, zircon and dolomite. The evolution of the mineralogical procession of the sands of the bars is not as clear as in the case of particle size parameters.

关键词： Characterization Granulometric Mineralogical Sands Middle Course Kasai River

Agricultural Contamination of the Surface Waters of the Upper Ouémé in Benin: The Case of Heavy Metals and Pesticides

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Journal of Agricultural Chemistry and Environment 2024年第1期13卷 83-99页

作者： Armelle Sabine Yélignan Hounkpatin Nonvignon Martial Fassinou Fadéby modeste Gouissi Zoulkanerou Orou Piami Dossou Armel Géraldo Houndeton Souradjou Orou Goura Wakili Bolatito Yessoufou Tayéwo Sylvain Biaou Laboratory of Hygiene Sanitation Toxicology and Environmental Health (HECOTES) The Training Centre Interfacultaire and Environmental Research for Sustainable Development (CIFRED) of the University of Abomey (UAC) Cotonou Benin Plurildisciplinary Research Laboratory for Technical Education (LARPET) of the University of Sciences Technologies Engineering and Mathematics of Abomey (UNSTIM) Lokossa Benin Laboratoire d’Ecologie de Santé et de Productions Animales (LESPA) Faculté d’Agronomie (FA) Université de Parakou (UP) Parakou Bénin

Objective: The main objective of this study was to assess the degree of contamination of surface waters by heavy metals and pesticides. Method: To this end, data were collected in December 2022 from four specific sampling stations: Okpara, Térou, Affon and Adjiro. Levels of heavy metals, including cadmium, chromium, copper, iron, mercury, nickel and lead, were measured and subjected to in-depth statistical analysis using graphical summation models. In addition, the concentrations of pesticide active ingredients present in the samples were interpreted and evaluated. The statistical data collected during this study were processed using R software, version 3.5.0. Results: The values obtained at the different stations Okpara, Térou, Affon and Adjiro are respectively Arsenic (2 × 10-4 mg/L;2.2 × 10-1 mg/L;1.2 × 10-4 mg/L;2 × 10-4 mg/L), Cadmium (4.4 × 10-5 mg/L;1.1 × 10-2 mg/L;10-4 mg/L;4 × 10-4 mg/L). Then Copper (7 × 10-4 mg/L;3 × 10-3 mg/L;7 × 10-4 mg/L;1 × 10-4 mg/L), Iron (1.51 mg/L;6.4 × 10-1 mg/L;2.0012 mg/L;2.9 × 10-1 mg/L), Lead (0 mg/L;0 mg/L;1.5 × 10-3 mg/L;1.5 × 10-3 mg/L). Mercury, nickel and chromium were not detected in surface waters. It is important to note that the values obtained for trace metals (Cadmium, Chromium, Copper, Iron, Mercury, nickel and chromium were not detected in surface waters. It is important to note that the values obtained for trace metals (cadmium, chromium, copper, iron, mercury, nickel and lead) were all below the guideline standards set by the WHO in 2006 for uncontaminated surface waters. This indicates that the surface waters of the Upper Ouémé were below acceptable contamination thresholds in terms of heavy metals. However, the presence of pesticide active ingredients such as cyfluthrin, endosulfan-alpha, endosulfan-beta, profenosfos, tihan, atrazine, g

关键词： Agricultural Contamination Heavy Metals Pesticides Surface Water North Benin

Assessment of forest dieback on the Moroccan Central Plateau using spectral vegetation indices

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Journal of Forestry Research 2023年第3期34卷 793-808页

作者： Youssef Dallahi Amal Boujraf modeste Meliho Collins Ashianga Orlando Laboratory of Microbial Biotechnologies Agrosciences and Environment(BioMAgE)Faculty of Sciences SemlaliaCadi Ayyad UniversityMarrakechMorocco Laboratoire des Productions Végétale Animales et Agro-industrieEquipe de BotaniqueBiotechnologie et Protection des PlantesFacultédes SciencesUniversitéIbn TofailKenitraMorocco Sociétés TerritoiresHistoires et PatrimoinesFacultédes Lettres et des Sciences HumainesUniversitéMohammed VRabatMorocco Rabat Morocco

Cork oak forests in Morocco are rich in resources and services thanks to their great biological diversity,playing an important ecological and socioeconomic *** degradation of the forests has been accentuated in recent years by signifi cant human pressure and eff ects of climate change;hence,the health of the stands needs to be *** this study,the Google Engine Earth platform was leveraged to extract the normalized diff erence vegetation index(NDVI)and soil-adjusted vegetation index,from Landsat 8 OLI/TIRS satellite images between 2015 and 2017 to assess the health of the Sibara Forest in *** results highlight the importance of interannual variations in NDVI in forest monitoring;the variations had a signifi cantly high relationship(p<0.001)with dieback *** was positively and negatively correlated with mean annual precipitation and mean annual temperature with respective coeffi cients of 0.49 and−0.67,highlighting its ability to predict phenotypic changes in forest *** interannual variation in NDVI between 2016 and 2017 seemed to confi rm fi eld observations of cork oak dieback in 2018,with the largest decreases in NDVI(up to−38%)in December in the most-aff ected *** of the infl uence of ecological factors on dieback highlighted the role of substrate as a driver of dieback,with the most severely aff ected plots characterized by granite-granodiorite substrates.

关键词： Forest health monitoring Remote sensing Dieback Vegetation indices Sibara forest