Abstract. Floods are devastating natural disasters with a significant impact on human life and the surrounding environment. This paper analyses historical and recent flood (2012 extreme) peak flow at strategic locations, land use activities and Floodplain Vulnerability Index analyses of the Niger-Benue River Floodplain. The 2012 peak flow at Jederbode on the Niger River was about 50 % above the long term average. At Jebba (Niger), the 2012 peak flow of 1567 m 3 s −1 was also far higher than the long term mean annual peak flow of 1159 m 3 s −1 . The 2012 peak flow at Lokoja was also about 50 % above the historical average. The Benue River at Makurdi had peak flow of 16 387 m 3 s −1 which was also unusually higher than the historical average while Wuroboki (Benue) had peak flow of 3362 m 3 s −1 which was also much higher that the historical average (694 m 3 s −1 ). The mixed land use which supported diverse ecosystem services has the largest cover of 5654 km 2 (36.85 %) of the Niger-Benue floodplain. The flood vulnerability of the various land uses within the floodplain include; medium, high and very high levels. A four levels hierarchical implementation adaptation strategy for sustainable agricultural practices along the rivers flood plain was proposed. The implementation hierarchy includes: Community Concern, Local Authority Concern, State Concern and National Concern.

Abstract. The Owo River is an important surface water source in Lagos particularly to the western section. It is the source of direct water intake for water supply by Lagos State Water Corporation to Amuwo-Odofin, Ojo and parts of Badagry Local Government Areas. This paper examines the complex interactions and feedbacks between many variables and processes within that catchment and analyses the future ability of this semi-urban watershed in sustaining water supply in the face of cumulative environmental change. Stationarity analysis on rainfall, change detection analysis and morphometry analysis were combined to analyse the non-stationarity of Owo River catchment. On rainfall trend analysis, since the correlation coefficient (0.38) with test statistic of 2.17 did not satisfy the test condition we concluded that there is trend and that rainfall in the watershed is not stationary. The dominant land use impacting on the bio-geochemical fluxes is built up area (including structures and paved surfaces) which grew from about 142.92 km 2 (12.20 %) in 1984 to 367.22 km 2 (31.36 %) in 2013 recording gain of 224.3 km 2 at average growth rate of 7.73 km 2 per annum. Total length of streams within the catchment reduced from 622.24 km in 1964 to 556 km in 2010, while stream density reduced from 0.53 in 1964 to 0.47 in 2010 an indication of shrinking hydrological network. The observed trends in both natural and anthropogenic processes indicated non-stationarity of the hydrological fluxes within the Catchment and if this continues, the urban ecosystem services of water supply will be compromised.

Abstract. Soil erosion is one of the most critical environmental hazards that causes land degradation and water quality challenges. Specifically, this phenomenon has been linked, among other problems, to river sedimentation, groundwater pollution and flooding. This paper assesses the susceptibility of Orashi River Basin (ORB) to soil erosion for the purpose of erosion control measures. Located in the South Eastern part of Nigeria, the ORB which covers approximately 413.61 km 2 is currently experiencing one of the fastest population growth rate in the region. Analysis of the soil erosion susceptibility of the basin was based on four factors including; rainfall, Land use/Land cover change (LULC), slope and soil erodibility factor (k). The rainfall was assumed to be a constant and independent variable, slope and soil types were categorised into ten (10) classes each while the landuse was categorised into five classes. Weight was assigned to the classes based on the degree of susceptibility to erosion. An overlay of the four variables in a GIS environment was used to produce the basin susceptibility to soil erosion. This was based on the weight index of each factors. The LULC analysis revealed that built-up land use increased from 26.49 km 2 (6.4 %) in year 1980 to 79.24 km 2 (19.16 %) in 2015 at an average growth rate of 1.51 km 2 per annum while the light forest decreased from 336.41 km 2 (81.33 %) in 1980 to 280.82 km 2 (67.89 %) in 2015 at an average rate 1.59 km 2 per annum. The light forest was adjudged to have the highest land cover soil erosion susceptibility. The steepest slope ranges between 70 and 82 • (14.34 % of the total land area) and was adjudged to have the highest soil susceptibility to erosion. The total area covered of the loamy soil is 112.37 km 2 (27.07 %) with erodibility of 0.7. In all, the overlay of all the variables revealed that 106.66 km 2 (25.70 %) and 164.80 km 2 (39.7 %) of the basin has a high and very high susceptibility to soil erosion. The over 50 % high susceptibility of catchment has serious negative implications on the surface water in terms of water quality and downstream siltation with great consequences on biodiversity and ecosystem services including domestic and industrial usage.

Introduction:Human activities exert great pressures on the environment which in turn cause environmental stresses of various intensities depending on the factors involved and the sensitivity of the receiving environment.Objective:This study examines the effects of anthropogenic activities along the sub-urban lagoon fragile coastal ecosystem using DPSIR framework.Results:The results show that the study area has undergone a tremendous change between 1964 and 2015 with the built up area increasing to about 1,080 ha (17.87%) in 2015 from 224 ha (1.32%) in 1964 at an average growth rate of 16.78ha per annum. The nature of the degradation includes an increasing fragility of the ecosystem through the emergence and expansion of wetlands, flooding and erosion as well as a reduction in the benefits from the ecosystem services. Population growth, between 2006 and 2015 for Ikorodu LGA, estimated at 8.84% per annum serves as the most important driving force in reducing the quality of the environment. This is in addition to Pressures emanating from anthropogenic activities. The state of the environment shows continuous resource exploitation (fishing and sand mining) with the impacts of the pressures coming from water pollution, bank erosion, biodiversity loss and flooding. Although there has been a strong policy formulation response from the government, weak implementation is a major challenge.Recommendation:The study recommends public awareness campaigns and the implementation of existing policies to ensure a sustainable sub-urban lagoon coastal environment..

Correlation and Multiple linear regression analysis was used to establish the degree of relationship and variability of groundwater quality parameters around Solous 1 and 2 Dumpsites, in Igando, Lagos, for the wet and the dry seasons. The correlation between TDS and other hydrochemical parameters which constituted the independent variables were positive, with significantly high positive correlation exhibited between TDS and EC for the wet season. For the dry season, the correlation between TDS and other groundwater quality parameters (EC, NO3-and Cl -) was positive, while its correlation with Zn 2+ and Fe 2+ was negative. The results of the multiple linear regressions for the wet and the dry seasons indicate that the model accounts for 96.8 percent and 93.9 percent, respectively of the variance of TDS concentration of groundwater around the dumpsites .@JASEM