Browsing by Author "Awotwi, Alfred"

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    Assessing the impact of anthropogenic activities and climate change on hydrology in Pra River Basin, Ghana
    (2019-05-31) Awotwi, Alfred
    This research investigated the climatic and land use and land cover changes on hydrology in the Pra River Basin, Ghana. Soil and water analysis tool model was adapted for the hydrological assessment. Double cumulative curve and visual image interpretation were used to select the satellite images for image classification. Markov- cellular automation model was used to predict future land use and land cover. Regional climate models data under representative concentration pathways 4.5 and 8.5 for the period 2022–2047, 2048-2073 and 2074-2099 were used for future climate change assessment. Weighting, scaling and ranking techniques were used to select models that best reproduce the observed data. Trend analysis of monthly, seasonal and annual rainfall showed significant reduction in the months of February and March at a rate of 73 mmyr−1 and 1.08 mmyr−1 respectively. Runoff analysis showed no significant change in the upstream part of Pra River Basin compared to the downstream showing significant upward trend with average rate of 465 m3 s−1 and 32.5 m3s−1 for the annual and dry season respectively. Anthropogenic activities and climate variability contributed 83 % and 17 % respectively to the changes in runoff between 1987 and 2010. Land use and land cover change analysis showed that cropland, settlement and mining areas increased respectively by 130.55 %, 198.45 % and 304.27 % between 1986 and 2016. Also, open forest, closed forest and water body declined respectively by 22.68 %, 41.50 % and 30.11 %. Changes in land use and land cover contributed to increase in surface runoff and water yield by 124.51 % and 40.13 % respectively. Baseflow and evapotranspiration reduced respectively by 30.08 % and 13.248 %. Impact of post- reclamation on hydrology showed that galamsey and small-scale backfilling contributed significantly to the increased annual surface runoffs and water yield, however, baseflow and percolation depicted significant reduction. The largescale mining showed no significant change in the hydrological components on reclaimed and natural background (unmined areas). Sediment yield from galamsey, small-scale and large-scale mining showed significant increase with reference to natural background. The representative concentration pathways 4.5 and 8.5 showed fluctuations in monthly and annual rainfall ranging between -14 % and 20 %. Climate change impact showed increase in streamflow throughout the study period. The study demonstrates the need to formulate sustainable strategies that will ensure conservation of the ecosystem.
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    Deforestation in forest-savannah transition zone of Ghana: Boabeng-Fiema monkey sanctuary
    (Global Ecology and Conservation, 2020-12-23) Amankwah, Afua Amponsah; Quaye-Ballard, Jonathan Arthur; Koomson, Bennetta; Amankwah, Richard Kwasi; Awotwi, Alfred; Kankam, Bright O.; Opuni-Frimpong, Nana Yeboaa; Baah, Douglas Siaw; Adu-Bredu, Stephen
    Forests provide many resources, ecosystem services and absorb carbon dioxide, which helps in climate regulation. In spite of the enormous benefits of forests, the issue of deforestation is still ongoing. There has been a continuous decline in forests globally and the forest area of Boabeng Fiema Monkey Sanctuary (BFMS) in Ghana is facing a similar threat. The aim of the study is to determine the different forest cover types and changes in the forest of BFMS. Satellite images for the years 1992, 1998, 2004, 2010, 2016 and 2018 were downloaded. Unsupervised and supervised classification were performed to determine the different forest cover types and remote sensing software was used to detect the changes in the forest cover. The forest cover was classified into six classes; closed forest, open forest, savannah woodland, savannah, farmlands and built-up area. Available data suggests that between 1992 and 2018, closed forest decreased by 242.19ha, open forest increased by 122.85 ha, savannah woodland increased by 7.47ha, savannah increased by 6.48 ha, farmland increased by 39.39ha and built-up area increased by 65.7ha. The changes in closed forest, open forest, farmland and built-up were all significant. Decreasing forest cover of BFMS is a threat to sustainable ecotourism since the forest serves as a habitat and food source to the monkeys. This research serves as guide to other researches aiming at determining forest cover changes in forest-savannah transition zones. In addition, the results have produced an inventory of the forest, which will help forest resource managers sustainably manage the forest.