Flood is one of the highly pronounced ruinous naturally occurring environmental hazards in which human lives and properties are gravely endangered. This study assessed areas prone to flood in Ibadan City, Nigeria. The study applied two multi-criteria analysis approach-Analytical Hierarchy Process (AHP) and the Fuzzy Analytical Hierarchy Process (FAHP) with the aid of GIS. Ten geomorphological physical characteristics agreed upon by experts as the major factors influencing the susceptibility of an area to floods formed the criteria maps used in this study. The natural breaks and geometrical interval clustering techniques were utilised to group the final flood-prone area maps into five categories-very low, low, moderate, high, and very high. The result indicated that over 50% of the study area either have low or moderate susceptibility to flooding. The clustering techniques showed some slight differences in the flood classifications where natural breaks consistently grouped more areas into the "very high" category and relatively fewer areas to "very low" category in comparison to the geometrical interval technique. Overall, at least 451 km 2 (about 15% of Ibadan) is highly or very highly prone to floods, and these areas are mainly concentrated in the urban and semi-urban regions of the study area. The findings and maps developed in this study would adequately serve as a planning guide for the policymakers on urban development and flood risk management to achieve sustainable development and management. K E Y W O R D S analytical hierarchy process, clustering techniques, flood-prone areas, fuzzy analytical hierarchy process, GIS, multi-criteria analysis 1 | INTRODUCTION Natural disasters have terrifyingly been escalating in many parts of the world, and their impacts have become one of the most subjects of concern in recent times. Such cataclysms include soil erosion, earthquakes, wildfires, and floods, whose occurrences customarily result in immeasurable losses of lives and properties every year

Abstract Soil erosion and mass movement processes spread across Anambra State in Nigeria, therefore making management and conservation techniques expensive and difficult in execution across the entire state. This study employed the Revised Universal Soil Loss Equation (RUSLE) model with the integration of geographic information system (GIS) and remote sensing techniques to assess the risk of soil erosion and hotspots in the area. Remotely sensed data such as Landsat 8 imagery, Shuttle Radar Topography Mission (SRTM) imagery, Era-Interim coupled with world soil database were used as digital data sources for land use map, digital elevation model, rainfall and soil data, respectively, to generate the Universal Soil Loss Equation (USLE) parameters. The results indicated vulnerability level in low, medium and high cover areas of 4,143.62 (91%), 332.29 (7%) and 84.06 (2%) km2, respectively, with a total soil loss between 0 and 181.237 ton/ha/yr (metric ton per hectare per year). This study revealed that high rainfall erosivity, steep and long slopes, and low vegetation cover were the main factors promoting soil loss in the area. Thus, the amount of soil loss in Anambra State is expected to increase with climate change and anthropogenic activities.

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In furtherance to the search for reliable and cost-effective road construction materials which is expected to engender the development of sustainable and less expensive pavements, coupled with the increase in agricultural wastes due to the current rise in the consumption of white meat, this research investigated the engineering properties of modified bitumen and subsequent performance of asphaltic concrete incorporating Pulverized Snail Shell Ash (PSSA) as strength modifier and filler. In order to achieve specific objectives, preliminary physical and chemical tests were initialized to characterize the virgin bitumen and snail shell ash. Pulverized proportions of the snail shell ash were blended with bitumen at 10 %, 20 %, 30 %, 40 % and 50 % respectively by weight of mineral aggregates; and subsequently incorporated as filler at the same proportions. The rotational viscometer and penetrometer were engaged to determine the viscosity and penetration of the modified bitumen, and the Marshall mix design method was used to determine the mechanical and rheological characteristics of the resultant asphaltic concrete composites. The modification of bitumen with snail shell ash resulted in a decrease in penetration of virgin bitumen from 80/100 pen to 60/70 pen, including the rotational viscosity. Different mixtures of PSSA at the aforementioned proportions, were evaluated by the design method according to Marshall. The stability was found to be higher than the control mix at 30% of grade which satisfied the Marshall specification for wearing course mixes. X-ray fluorescence (XRF) showed the presence of Oxygen and Calcium in the Hot Mix Asphalt (HMA) modified with PSSA, while the scanning electron microscope (SEM) showed a good blend of the aggregates. The results suggest feasible use of PSSA as partial aggregate substitution in HMA. It was noted that the PSSA was finer than the conventional mineral filler and it filled the voids, engendered a stiffer, and denser mix, as well as reduced the number of voids present in the mix and increased its stability. Experimental results indicated higher stability value of 35.08 KN for the mixture having 30% PSSA as optimum filler content in comparison with conventional mix which was 34.7 kN and standard specification of 34 kN minimum. This study has therefore established the feasibility of using PSSA as alternative filler instead of the conventional in asphalt concrete mix by satisfying the standard specification. Also making the reuse of agricultural waste possible, thereby making construction cost cheaper, and also reducing waste.

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