Morphological characteristics and changes in the Upper Reach Gumara River in Ethiopia from 1957 to 2020

Abstract

Human intervention with the natural landscape, including various river systems, is increasing in most parts of our country due to population growth and their infinite demand. As a result of this, the river system was jeopardized, causing irreversible damage to the socioeconomic and infrastructural systems. Morphological characterization and change evaluation of rivers are essential prerequisites for investigating their historical evolution and making reasonable estimates about how rivers might adapt to changing natural conditions and increasing anthropogenic impacts. This study focuses on the upper reach of the Gumara River along a 47.336 km stretch because it is a highly meandering and dynamic fluvial system with minor natural and anthropogenic influences that harm living and nonliving things around the flow path. We use satellite images as a data source, and the study reach was divided into six sections based on the waterway geometry and various forms of human intervention along the river, for detailed river morphological characterization and change detection, and to know the disturbance that facilitates the change in sub reach. In addition to satellite imagery, field observations, informal interviews with local indigenous people, laboratory analysis of bank material, and Meteorological and Hydrological data were used. The primary goal of this study was to assess the Morphological Characteristics and Change of the Upper Reach Gumara River over a 64-year period in Tana Basin, Ethiopia. Image analysis software (ERDAS Imagine 2015 and Arc GIS 10.5) was used for data preparation and analysis, and to characterize and detect the change of study reach, various morphometric parameters such as Sinuosity index, braided index, River center line, actual River length, river width, meander neck length, and River area were determined. From the entire period of 64 years of sinuosity index analysis, the sinuosity was increased by 5.49%. The section between five and six had a 63% reduction in neck length. Over a 64-year period, the overall width increased by 0.348 m per year. All of the morphometric parameter results and social information show that the upper reach of the Gumara River was dynamically changed and disrupted the surrounding socioeconomic system, implying that critical measurements should be designed and implemented.