Riverbed Classification and Evaluation of Woji Creek, Port-Harcourt, Nigeria using Side Scan Sonar Technology

Abstract

Woji Creek is vital for vessel navigation, flora and fauna habitats, and local livelihoods.. The study aims to classify and evaluate the riverbed in Woji Creek, Port Harcourt, Nigeria using side scan sonar technology. Its objectives are to; classify and evaluate the riverbed of Woji Creek using side-scan sonar technology, analyse and quantify the variations in water depth throughout Woji Creek, evaluate the water volume of Woji Creek for navigational suitability purposes and determine the turbidity levels of Woji Creek. The methodology involved the acquisition of Side-Scan Sonar (SSS) and Sub-bottom profile Data. The data acquired underwent backscatter processing to obtain a geocoded back scatter image from which feature points were extracted and matched. The matched images were used to derive a riverbed classification, depth classification, water volume analysis and river turbidity analysis. The riverbed classification identified three predominant sediment types: Clayey Silty Sand, Silty Clay, and Silty Sand, each with distinct implications for navigation. Clayey Silty Sand, covering 43.11% of the riverbed, poses challenges due to its cohesive nature and sand content, potentially leading to increased frictional resistance and the formation of sandbars. The depth classification analysis revealed the presence of Shallow, Moderate, Deep, and Very Deep areas within Woji Creek. Shallow areas (24.22% of the total area) may pose challenges for vessels with deeper drafts, while Moderate areas (30.54%) offer improved navigability. Deep areas (41.25%) provide favorable conditions for navigation, and Very Deep areas (3.98%) accommodate vessels with extreme drafts. The water volume distribution analysis is crucial for assessing depth limitations and planning routes. Shallow areas (11.15%) present smaller volumes, potentially posing navigational challenges. Moderate (25.65%) and deep (31.72%) areas offer larger volumes, facilitating navigation for vessels with moderate and deeper drafts, while Very Deep areas (31.49%) provide substantial volumes that require careful navigation. The assessment of river turbidity identified low (70.43%), moderate (23.67%), and high (5.91%) turbidity zones. Low turbidity indicates clear water with minimal suspended particles, while moderate and high turbidity suggest increased particle concentration and reduced visibility