Papers by Kueshi Semanou Dahan
Forest-Savannah transition zones are increasingly vulnerable due to their position between the sa... more Forest-Savannah transition zones are increasingly vulnerable due to their position between the savannah and forest ecosystems, and their ecological and biophysical characteristics. This study evaluates the spatiotemporal dynamics of land use and land cover (LULC), degradation, and wildfire links. Random Forest (RF) classifier was used in Google Earth Engine (GEE) with Landsat 7 and 8 imageries (2001, 2015, 2023), high-quality LULC maps were produced with spectral indices. The classifier demonstrated accuracies ranging from 83% to 96%, supported by F1-Score, Precision, and Recall metrics. Overall, Wooded Land and Gallery Forest increased by 35.29%, followed by Savanna Grassland and Farmland (16.2%). Conversely, Rock Outcrop declined by 23.6%, while Bare and Built-Up Areas, Dense Forest, Water Bodies, and Mosaic Forest-Savannah decreased by 13.7%, 6.9%, 4%, and 3.7%, respectively. Savannah and farmland areas were the most burned (30-36%), followed by 25 Wooded Land (21-24%) and Dense Forest (10-14%). Savannah areas also experienced the highest fire frequency (19 events). Fire occurrence was higher in areas with low vegetation cover than densely vegetated areas and conservation zones. Savannah and farmland remained the most degraded and fire-prone. An improved monitoring approach is needed for reduction and mitigation to avoid irreversible degradation caused by wildfire.
Towards understanding the environmental and climatic changes and its contribution to the spread of wildfires in Ghana using remote sensing tools and machine learning (Google Earth Engine)
International Journal of Digital Earth, Apr 17, 2023
Environment and Natural Resources Research, May 26, 2022
Research in the world, and more specifically in Africa, on various subjects requires knowledge of... more Research in the world, and more specifically in Africa, on various subjects requires knowledge of previous work from several angles in order to orientate possible research. Thus, the literature review is considered the most suitable approach to have a more complete idea of the innovations or studies carried out on varied topics. To this end, on the issues of vegetal cover protection, environmental management and wildland fire in Ghana, we have adopted this review approach to identify the works already done in Ghana on wildland fire, the methodologies and angles that studies approached their objectives. This paper aims to review and provide a comprehensive report on research works done on the vulnerable vegetation of Ghana by bush fires. Thus, studies published from 1940 to 2021 were extracted from Research Gate, Google Scholar and Google and other indexed journal sites such as Scopus journals using a defined selection criterion. A total of 136 documents: these include reports of international organisations and relevant articles extracted. However, 52 of them were used for this review to better understand their approach and to highlight research gaps that could make those researches innovative. It is noted that most of the research done in Ghana on wildland fire analysis has little or no consideration for the influence of climatic and environmental parameters on understanding wildland fire behaviour, though some respondents from some research show their awareness of the role these parameters play on the fire propagation. However, it should be noted that the majority of studies have focused more on sociological and economic aspects. This observation thus reflects gaps in areas regarding the roles of climatic and environmental parameters in different ecological conditions to better assess the behaviour of wildfires in Ghana.
Background Two of Ghana’s ecological zones—Guinea-savanna zone (GSZ) and Forest-savanna mosaic zo... more Background Two of Ghana’s ecological zones—Guinea-savanna zone (GSZ) and Forest-savanna mosaic zone (FSZ)—are practically homologous in terms of structure and floristic composition, with some differences. The various sub-ecosystems that make up these areas are being depleted and losing their natural values due to various threats. There is little understanding about the fire trends in these areas due to lack of data and poor accessibility to existing fire statistics. This study aimed to contribute to the understanding of the trends of area burned and active fire in the Guinea-savanna and Forest-savanna mosaic zones in order to inform policy-makers about sustainable management options. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) daily active fire (MDC14ML) and burned-area (MCD64A1) products to characterize the fire regime in terms of seasonality, intensity, density, a burned area, frequency, and the trends during the study period of 2001 to 2021. Results This stu...
European Journal of Remote Sensing , 2025
Forest-Savannah transition zones are increasingly vulnerable due to their position between the sa... more Forest-Savannah transition zones are increasingly vulnerable due to their position between the savannah and forest ecosystems, and their ecological and biophysical characteristics. This study evaluates the spatiotemporal dynamics of land use and land cover (LULC), degradation, and wildfire links. Random Forest (RF) classifier was used in Google Earth Engine (GEE) with Landsat 7 and 8 imageries (2001, 2015, 2023), high-quality LULC maps were produced with spectral indices. The classifier demonstrated accuracies ranging from 83% to 96%, supported by F1-Score, Precision, and Recall metrics. Overall, Wooded Land and Gallery Forest increased by 35.29%, followed by Savanna Grassland and Farmland (16.2%). Conversely, Rock Outcrop declined by 23.6%, while Bare and Built-Up Areas, Dense Forest, Water Bodies, and Mosaic Forest-Savannah decreased by 13.7%, 6.9%, 4%, and 3.7%, respectively. Savannah and farmland areas were the most burned (30-36%), followed by 25 Wooded Land (21-24%) and Dense Forest (10-14%). Savannah areas also experienced the highest fire frequency (19 events). Fire occurrence was higher in areas with low vegetation cover than densely vegetated areas and conservation zones. Savannah and farmland remained the most degraded and fire-prone. An improved monitoring approach is needed for reduction and mitigation to avoid irreversible degradation caused by wildfire.
Background Two of Ghana's ecological zones-Guinea-savanna zone (GSZ) and Forest-savanna mosaic zo... more Background Two of Ghana's ecological zones-Guinea-savanna zone (GSZ) and Forest-savanna mosaic zone (FSZ)-are practically homologous in terms of structure and floristic composition, with some differences. The various sub-ecosystems that make up these areas are being depleted and losing their natural values due to various threats. There is little understanding about the fire trends in these areas due to a lack of data and poor accessibility to existing fire statistics. This study aimed to contribute to the understanding of the trends of area burned and active fire in the Guinea-savanna and Forest-savanna mosaic zones in order to inform policy-makers about sustainable management options. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) daily active fire (MDC14ML) and burned-area (MCD64A1) products to characterize the fire regime in terms of seasonality, intensity, density, burned area, frequency, and trends during the study period of 2001 to 2021. This study indicated that fire activity started in October and peaked in December (GSZ) and January (FSZ). The mean proportion burned was approximately 39.95% (burned area of 2659.31 km 2 ; FSZ) and 60.05% (burned area of 3996.63 km 2 : GSZ), while the frequency was approximately 42.87% (1759.95 of active fires; FSZ) and 57.13% (2345.26 of active fires: GSZ). In 2018, GSZ recorded the largest burned area (19 811.2 km 2 , which represents an average of 825.5 km 2 of the total area burned from 2001 to 2021) with 4719 active points detected. FSZ recorded its greatest burned area in 2015 (8727.4 km 2 ; which represents an average of 363.6 km 2 of the total area burned from 2001 to 2021) with 5587 active points recorded. In addition, it was found that specific times of the day (1000 h to 1420 h) recorded the majority of burned areas. In overview, between 2001 and 2021, burned areas increased by an average of 1.4 km 2 (FSZ) and 4.6 km 2 (GSZ), and the number of active fires increased by an average of 4.7 (FSZ) and 4.4 (GSZ) active fires per km 2 . Conclusions In conclusion, burned areas and active fires are increasing in both ecological zones. This study demonstrated the relevance of remote sensing to describe spatial and temporal patterns of fire occurrence in Ghana and highlighted the need for fire control and fuel management by the policies and institutions (e.g., Ghana National Fire and Rescue Service) in these important and vulnerable zones (GSZ and FSZ). This is especially true in the Forest-savanna mosaic zone, which is increasingly affected by the disasters of wildfires and records more active fires than GSZ, indicating that this zone is becoming more and more vulnerable. Therefore, rigorous continuous monitoring is essential, and collaboration between organizations fighting for the conservation of natural resources in the field is strongly recommended.
Thesis Chapters by Kueshi Semanou Dahan
University for Development Studies, 2023
Ghana is increasingly affected by climate change, increased soil aridity, demographic problems, a... more Ghana is increasingly affected by climate change, increased soil aridity, demographic problems, and other unfavourable environmental factors. All these factors are affecting forest resources, slowing down stakeholders’ efforts. In the context of conservation, protection and sustainable management, this study aimed at improving knowledge of the recurrence of wildfires and their evolution over time in the context of climate change for the sustainable management of forest resources in different eco-regions in Ghana. Specifically, it sought to contribute to the understanding of the trends of area burned and active fire (2001-2021) in the Guinea-savanna and Forest-savanna mosaic zones to inform policy-makers about sustainable management options. Also, to understand climate’s link (2001-2021) and its impact on the burned areas in Ghana, assessed the loss, gain and stable areas of vegetation cover and the potential contribution of fire to vegetation degradation considering the vegetation dynamics cover and assess the contribution of climate and environmental changes to the spread of bush fire through prediction. The research was conducted in four districts namely West Gondja and West Mamprusi (Guinea-savannah zone (GSZ)); Sene and Afram Plains (Forest-savannah mosaic zone (FSZ)) to make a comparative analysis on the level of intensity and degradation of forest resources. The Moderate Resolution Imaging Spectroradiometer (MODIS) daily active fire (MDC14ML) and burned area (MCD64A1) products were used. Characterization of the fire regime in terms of seasonality, intensity, density, burned area, frequency, and the trends during the study period of 2001 to 2021. Machine learning approach, through Google Earth Engine (GEE), codes were developed to retrieve data such as rainfall (PR), maximum temperature (Tmax), minimum temperature (Tmin), average temperature (Tmean), Palmer Drought Severity Index (PDSI), relative humidity (RH), wind speed (WS), soil moisture (SM), actual evapotranspiration (ETA) and reference evapotranspiration (ETR). the data were retrieved from CHIRPS (Climate Hazards group Infrared Precipitation with Stations), FLDAS dataset (Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System) and TerraClimate platform from 1991 to 2021. Concerning vegetation dynamic assessment remote sensing, GIS and quantitative analysis approaches were used and applied on Landsat ETM+, OLI TIRS and Sentinel 2B images (2001, 2011, 2021). The
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random forest regression model was used for fire prediction. The outputs of the CCLM4-8-17 model were used and analysed under RCP4.5 and RCP8.5 to predict the climate of the ecological zones considered in this study. Thus, burned areas and active fires are increasing (2001.2021) in both ecological zones (1.4 km2 (FSZ); 4.6 km2 (GSZ), for active fires, 4.7 (FSZ) and 4.4 (GSZ) per km2), and contribute to the vegetation cover dynamic and its degradation. The parameters, both climatic and environmental, contribute to the fire spreading in GSZ and FSZ with increasing of temperature and decreasing of precipitation (-0.1 mm; +0.8˚C in GSZ and -0.9 mm; +0.3˚C in FSZ). Thus, in the GSZ, tmax, SM, and ETA contribute more to fire activity and spread under the RCP4.5 and RCP8.5 scenarios. However, in the FSZ, RH, tmax, and SM contribute more to fire activity and spread under the RCP4.5 and RCP8.5 scenarios respectively. Based on the results, rigorous continuous monitoring in collaboration with organizations and institutions (NGOs, Ghana Fire Service) fighting for the conservation of natural resources in the field is strongly recommended.
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random forest regression model was used for fire prediction. The outputs of the CCLM4-8-17 model were used and analysed under RCP4.5 and RCP8.5 to predict the climate of the ecological zones considered in this study. Thus, burned areas and active fires are increasing (2001.2021) in both ecological zones (1.4 km2 (FSZ); 4.6 km2 (GSZ), for active fires, 4.7 (FSZ) and 4.4 (GSZ) per km2), and contribute to the vegetation cover dynamic and its degradation. The parameters, both climatic and environmental, contribute to the fire spreading in GSZ and FSZ with increasing of temperature and decreasing of precipitation (-0.1 mm; +0.8˚C in GSZ and -0.9 mm; +0.3˚C in FSZ). Thus, in the GSZ, tmax, SM, and ETA contribute more to fire activity and spread under the RCP4.5 and RCP8.5 scenarios. However, in the FSZ, RH, tmax, and SM contribute more to fire activity and spread under the RCP4.5 and RCP8.5 scenarios respectively. Based on the results, rigorous continuous monitoring in collaboration with organizations and institutions (NGOs, Ghana Fire Service) fighting for the conservation of natural resources in the field is strongly recommended.