Browsing by Author "Attua, E. M."

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Flood hazard response to scenarios of rainfall dynamics and land use and land cover change in an urbanized river basin in Accra, Ghana
(City and Environment Interactions, 2021) Pabi, O.; Egyir, S.; Attua, E. M.
Understanding of flood hazard response to multiple scenarios of relevant determinants in urban centers is a precondition for proactive disaster risk management. Yet, studies on flood response to the effects of multiple agents in Sub-Saharan Africa countries is rare. This study simulates peak runoff and water flow rate to land use and land cover (LULC), and scenarios of rainfall intensity of different durations and return periods. An urban flood-prone Odaw River catchment of Accra, Ghana was studied for the possible hazard responses to variations in LULC and rainfall intensities and amounts. Landsat data for 2000, 2011 and 2020 were classified and analyzed for changes in LULC. Rainfall intensity was estimated for different durations; and 2, 10 and 25 years of return periods, using Intensity-Duration-Frequency (IDF) model. The rational and the successive flow routing hydrological models were used to simulate peak runoff and flow rate, respectively. Built-up area increased in coverage from 40% in 2000 to 65% in 2020, whereas woodland reduced from 10.5% to 4.0% for the same period. The peak runoff was highest in the built-up areas, and directly proportional to rainfall intensities and return periods. Replacing a given amount of woodland by equal amount of built-up area increased peak discharge by 3.5 times. Runoff peaked 30 mins after onset of rainfall for the 10-yr and 25-yr return periods, but peaked 1 hr for the 2-yr return period. We recommend that flood risk reduction strategies maintain substantial amount of woody vegetation and grassland, and provide quick early warning when extremely high rainfall intensity is anticipated. Land use planning organization should consider a range of flood hazard intensities, including rare and extreme events in their decisions.
GIS-multi criteria assessment of land suitability and optimal sites allocation for large scale pineapple production in the Akwapim South District, Ghana
(Ghana Journal of Geography (2): 43-56, 2010) Attua, E. M.
Land suitability assessment, in the context of land use planning, is a bridging phase linking land resources assessment to any land use decision-making process. Like elsewhere, land use suitability assessment in Ghana is influenced by inherent conflicts and a complex network of socio-economic and ecological constraints that call for a flexible decision-making support tool able to incorporate multiple evaluation criteria, including the opinions of several stakeholders. In this paper, we report on a GIS-based multi-criteria approach to land suitability evaluation for pineapple production in the Akwapim South Municipality of Ghana. The crop is an important export earner, having contributed significantly to foreign exchange receipts of the country since the 1980s, although its cultivation has also increased land use conflicts and aggravated land degradation. The study relied on several decision support tools such as high spatially-resolved remotely sensed data, geographical information system (GIS) and multi-criteria decision analysis (MCDA), including analytical hierarchy process (AHP). The approach enabled decision makers to evaluate the relative priorities of locating sites for cultivation of the crop, based on a set of preferences, criteria and indicators. Weighted Linear Combination (WLC) techniques were used to integrate fuzzy suitability criteria maps of decision groups and a consistency ratio between criteria was calculated using the Saaty matrix cross-comparison technique. An iterative post-aggregation constraint was applied to identify potential sites as basis for delineating potential areas for pineapple cultivation. In the context of potentially high export market demands of the crop and its significant economic contribution to the local economy, this study is of national relevance. Moreover, the results in form of maps may also be used by agricultural managers as decision-support tools, for instance, to outline the most suitable land areas for subsidy support for increased pineapple production in the district.
Hazards and Vulnerability Mapping for Adaptation to Climate Risks in Savannah Ecosystem: A Case Study of the Upper East Region, Ghana
(University of Ghana, 2014-07) Yiran, G. A. B.; Gyasi, E. A.; Attua, E. M.; Owusu, K.; University of Ghana, College of Humanities, School of Social Sciences, Department of Geography and Resource Development
The climate is warming, a trend that is projected to increase with increasing frequency and intensity of climate related hazards. Impacts are likely to be greater in developing countries because of dependence on climate sensitive livelihood activities. The nature and impacts of climate hazards require a study that goes beyond investigating a single hazard or livelihood activity to embrace multiple hazards and their impacts on the various livelihood activities. It is against this background that this research was set up to undertake a multi-hazard/multi-sector analysis and mapping of vulnerability and identify policy options to enhance adaptation in the savannah ecosystem, using the Upper East Region as a case study. To achieve this, an integrated framework was developed to guide the research. Assessment of the various components of the framework required varied datasets and different methods of data collection and analysis. The primary data was collected using questionnaires, focus group discussions, photography, as well as personal observation. The secondary data consisting of daily weather and socio-economic and geographic data was collected from relevant institutions, policies and published reports. The weather data was analysed using the Standard Precipitation Index and plotted with R. The questionnaire survey and socio-economic data was analysed using Statistical Package for Social Science and Excel while the focus group discussions were subjected to manual content analysis. The datasets were used to develop indicators of exposure, sensitivity and adaptive capacity and converted into geographic layers for mapping in ArcGIS 9.3. The individual indicators were georeferenced using the district boundaries since most of these datasets were collected at district scale.
Sustainable land-use evaluation on steep landscapes and flood plains in the New Juaben district of Ghana: A GIS Approach
(Ghana Journal of Geography (1): 115-134, 2009) Attua, E. M.; Opoku, P.
Specific criteria are stipulated and recommendations made for the sustainable management of landscapes in Ghana. Yet, evaluation is scarcely conducted to determine whether real performance of land-use strategies are meeting expected standards of suitability. The paper reports on an evaluation study conducted on a landscape with various levels of slopes and flood plains. The study sought to demonstrate the application of information technology in achieving the objectives of sustainable land-use management. Landscape of the area was modeled in a Geographic Information System (GIS) environment. Slope was derived from digital elevation model (DEM) and spatially analyzed with land use-/cover information generated from satellite data. The performance of existing land-use was compared with expected land use performance criteria for steep landscapes and flood plains. Steep slopes and areas within 100m of the Densu River have been denuded of forest vegetation. Rather than making only a marginal use of geo-information technology in generating data, we must leverage its inherent analytical potentials that enable innovative, creative and enhanced management decisions for sustainable land resource use. Continually monitoring and evaluating the performance of land-resource utilization will provide feedback information necessary for directing resource use on sustainable trajectories.