No abstract
Rivers constitute an important focus of attention in surface water studies because of their dynamic nature. Therefore, natural rivers develop a wide range of channel forms whose characteristics vary as a function of the position within the fluvial systems. This study examined the river channel morphologic parameters along the alluvial section of River Ogun in South western Nigeria. Data on the channel morphologic variables were collected through field measurement of the bankfull cross sectional characteristics of the river from where the longitudinal characteristics were defined. 48 cross sections were randomly established at bankfull stage along the river channel stretch of 90 km. Bankfull depth and width at each of the cross sections were determined using sonar (electronic sounding machine) that was mounted to a boat. Velocity was measured with the aid of a current meter, while other morphological parameters were estimated from the field data. Analysis of variance revealed that downstream morphological characteristics of the river varies distinctively at each cross section with bedslope as the most significantly varied among all other morphologic parameters (F=91.18; P=0.00). Pearson product moment correlation technique revealed that bankfull width had a correlation of 0.8 and 0.9 with wetted perimeter and cross sectional area respectively while bankfull depth (maximum) had correlations of 0.9, 0.8 and 0.78 with hydraulic radius, wetted perimeter and cross sectional area respectively. The research also revealed that gradient affects the discharge with a positive correlation of 0.9. The study ascertains the extent of variability in the morphologic characteristic of River Ogun which provides scientific basis for river maintenance and management.
The River Continuum Concept (RCC) is an existing theory regarding the distribution of plant communities along riverbanks. This study is concerned with the pattern of riparian vegetation along the Lower Ogun River (LOR) in relation to the observed downstream variation of various environmental factors (bank height, width, gradient, distance, cross‐sectional area and particle size). The LOR transits between undisturbed and disturbed sections. Forty‐eight cross sections were established at bankfull stage along the river channel stretch of about 90 km. Environmental variables distribution were determined using standard field procedures. Gradient was estimated from a 1:50 000 topographical map. At each corridor along the study sites, a 0.1 ha sampling site was chosen, in which 10 transects of 100 m2 were demarcated. In all, 332 individuals stratified under 80 species were recorded across the transects. The study revealed that total species richness (TSR) downstream decreases exponentially. TSR is significantly correlated with channel width, suggesting that hydraulic variable contributes more to the variation in TSR. The downstream total environmental factors revealed that width is inversely significant with downstream distance, suggesting that the river channel is narrower downstream. This affects plant life form distribution downstream and confirms why there is appearance of anthropogenic induced species downstream as against those in the upper course.
This paper draws from the experiences of a Non-Governmental Organisation, Man and Nature Study/Action Centre (MANASC)—concerning a rural development project being undertaken in Olugbena, a group of six villages in Ewekoro Local Government of Ogun State, Nigeria—to highlight the challenges of participatory rural development in Africa. The project part, funded by the Australian High Commission in Nigeria under its Direct Aid Scheme, comprises a component of a much broader development plan for the area as contained in a pre-feasibility report undertaken in 1995 by MANASC for the National Primary Health Care Development Agency (NPHCDA), a Parastatal of the Federal Ministry of Health. It is observed that one of the challenges for rural development facilitators, policy makers and practitioners, revolves around appropriate strategies for managing unpredictability, especially those that reduce the unknown elements to acceptable levels and impose the minimum of appropriate structures. développement plus large, destiné à cette zone, tel que prévu dans un rapport de pré-faisabilité préparé en 1995 par le MANASC (pour la «National Primary Health Care Development Agency» - Agence Nationale pour le Développement des Soins de Santé de Base - (NPHCDA), une structure semi-publique du Ministère Fédéral de la Santé. Il a été noté que parmi les défis auxquels sont confrontés les facilitateurs, décideurs et praticiens du développement rural, figure la définition de stratégies adaptées à la gestion des imprévus, particulièrement celles qui permettraient de réduire les éléments imprévus à des niveaux acceptables et qui favoriseraient la mise en place de structures appropriées.
The term region has its origin in geographical studies and refers to a more or less defined portion of the earth's surface distinguished either by natural features (e.g., climate, vegetation, landform) man-made features (e.g., settlement and other forms of landuse), or both. The main characteristic of either type of region is functional unity and relative homogeneity, which together minimize effort, whether in terms of the natural processes or the amelioration and control of these processes for purposes of development.
The supply of adequate water is cited as one of the major challenges to governments in developing countries, mainly because communities in many countries have come to depend almost entirely upon governments for the provision of that vital resource. Some reasons for poor performance of government water supply projects are given. Recent developments at the Federal level in Nigeria, which should substantially improve the domestic water supply situation, are described. It is suggested that governments will have to change their practice of concentrating on large‐scale schemes to one of undertaking several small‐scale schemes simultaneously through the pooling of government and local, especially community self‐help, resources. L'un des principaux problèmes que rencontrent les gouvernements des pays en développement est celui de l'alimentation en eau en quantité suffisantes car les collectivités dans de nombreux pays en sont arrivées à dépendre presqu'entièrement du gouvernement pour l'approvisionnement de cette ressource vitale. Cet article donne quelquesunes des raisons qui peuvent expliquer les maigres résultats obtenus par un gouvernement lorsqu'il s'agit de projets d'alimentation en eau. Il relate des travaux récents entrepris au niveau fédéral au Nigéia et qui devraient améliorer de manière substantielle l'alimentation en eau des foyers domestiques. Il est suggéré que les gouvernements devraient modifier leur politique qui consiste à ne s'intéresser qu'à des projets de grande dimension pour réaliser de manière simultanée plusieurs projets à petite échelle en mettant en commun les moyens gouvernementaux et locaux et, plus spécialement, l'aide que peuvent apporter les communautés. El suministro suficiente de agua es considerado como uno de los desafíos mayores para los gobiernos de los países en desarrollo, debido a que en la mayoría de estos países las comunidades dependen casi enteramente en el gobierno para el suministro de este recurso tan vital. Se señalan algunas causas de la acción deficiente del gobierno en los proyectos de suministro de agua. Se describen desarrollos recientes a nivel federal en Nigeria los que posiblemente mejorarán sustancialmente el suministro doméstico de agua. Se sugiere que los gobiernos tienen que cambiar la práctica de concentrarse en esquemas de gran envergadura hacia el desarrollo de proyectos de pequéna escala aprovechando simultaneamente recursos del gobierno nacional, local y, especialmente, la participación de los consumidores.
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