Speakers
Description
Globally, river systems are continually undergoing morphological changes due to natural factors and human activities. The Offin River in Ghana has also experienced significant changes due to increased illegal mining, agriculture, and deforestation, which pose serious ecological and social problems. The study used GIS and Remote Sensing Technology to contribute to establishing a baseline on the extent of morphological changes caused mainly by illegal mining. Using Landsat 5 TM for 1986 and Landsat 8 OLI for 2015 and 2024 a supervised classification method using the Random Forest Classifier algorithm in the Google Earth Engine was used in the classification process, while ArcMap 10.7.1 was used to create a spatiotemporal map and calculate changes in morphological parameters such as channel area, channel width, channel length and sinuosity index. The findings revealed that the Offin river's area increased sharply from 2015 to 2024 from 3051.0 ha (1.3%) to 5173.7 ha(3.0%) respectively, and the length also increased in 2015 to 2024 from 243.1km (0.1%) to 261.6km (0.2%) respectively, when using 1986 values as the base for comparison. This was reflected by increased lateral migration and widening of channel of the spatiotemporal maps. However, the channel width decreased from 434.6m (2.4%) to 301.5m (1.4%) after 2015. The recorded sinuosity index for all selected years were greater than 2, indicating an extremely sinuous river. The findings of this study provide accurate scientific information on the morphological changes in the Offin river, which is mostly driven by illegal mining and deforestation, which policymakers, authorities, and the public can employ for effective and efficient planning and monitoring of the Offin river.
Keywords: river dynamics; watershed; galamsey; basin conditions; water resources