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The acute shortage and scarcity of lands for suitable waste disposal is rapidly becoming a critical growing potential problem in most urban cities in developing countries of the world, and several fast-growing cities in Nigeria are not exempted from this menace. In this study, geographic information system (GIS) and analytic hierarchy process (AHP) are combined to select the most suitable landfill location in Lokoja, Nigeria. The landfill site selection criteria considered include proximity to major road, powerline, water body, landfill areas and built-up area. GIS was used to digitize spatial features related to unsuitable landfill site. A total of 19 candidate landfill sites were identified from GIS analysis. AHP model was developed from the GIS result as multi-criteria decision tool in evaluating each candidate site so as to choose the best appropriate landfill site. AHP model rated candidate site 11 located along Jimgbe road has the most preferable site to locate a landfill in Lokoja with an approximate area of 3.4204 km 2 ; the distance from the minor road, nearest water body, powerline and built-up areas to the location is 210.50 m, 1408.20 m, 1810.80 m and 205.61 m, respectively. Also, the model rated candidate site 16 located along 500 housing units as the least preferable site to locate a landfill in Lokoja. The characteristic features of the site location as obtained from GIS analysis include an approximate area of 2.5680 km 2 at an approximate distance of 2430.75 m, 594.04 m, 1980 m and 200.68 m from the major road, water body, powerline and built-up areas, respectively. This result will greatly serve as guide in landfill site selection in major urban states of other developing countries.

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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

Wastewater reuse is an attractive option for supplementing available water supplies. Benefits of reuse include pollution abatement due to the reduction of effluent discharge to surface water bodies, the decrease in the use of freshwaters from sensitive ecosystems, replenishment of soil nutrients in agriculture, enhancement of groundwater recharge and delay in the future expansion of water supply infrastructure. This paper presents ongoing research in developing and testing of a decision support system (DSS) for assessing the feasibility of implementing wastewater reuse projects in South Africa. The DSS employs multi-criteria qualitative assessment across technical, environmental, social, institution and water resources. The database of the DSS contains 33 wastewater treatment unit processes with known information on performance, costs and qualitative criteria obtained from literature. The knowledge base on the other hand, consists of a set of rules for combining the treatment units to form treatment trains and contains information on maximum allowable values for different water quality parameters for five end users. The weighted average method was used to aggregate scores obtained from the assessment of the different criteria to generate an indicative value that could form the basis for decision making. Testing of the DSS was applied to the Parow wastewater treatment plant in Cape Town. Results of the analysis shows that only the water resources evaluation score (1.0) is considered excellent for reuse implementation while the institutional evaluation score is weak (0.35) in guaranteeing success. Social evaluation and treatment train technical/environmental have qualitative evaluation scores of 0.76. The desirable score for all the criteria is 1.0 in order to facilitate the successful implementation of any reuse project. The quality of treated effluent from the proposed treatment trains meets the quality requirement in most of the pollutant determined except total phosphorus (2.88). The value is acceptable if the use of the effluent is limited to irrigation. If decision makers give adequate attention to the criteria highlighted in this model, success of a reuse project in South Africa can be better enhanced.

Wastewater reuse is increasingly becoming an important component of water resources management in many countries. Planning of a sustainable wastewater reuse project involves multi-criteria that incorporate technical, economic, environmental and social attributes. These attributes of sustainability is the framework upon which the decision support tool presented in this paper is developed. The developed tool employs a user friendly environment that guides the decision makers in assessing the feasibility of implementing wastewater reuse. The input data into the tool are easily obtainable while the output is comprehensive enough for a feasibility assessment of treated wastewater reuse. The output is expressed in terms of effluent quality, costs, quantitative treatment scores and perception evaluation. Testing of the developed multi-criteria decision support tool using Parow wastewater treatment works in Cape Town showed the tool to be versatile and capable of providing a good assessment of both qualitative and quantitative criteria in the selection of treatment trains to meet various non-potable reuses. The perception module provided a quick assessment of potential user’s concerns on reuse and service providers’ capacity.