Morphometric Change Detection of Lake Hawassa in the Ethiopian Rift Valley

Abstract

The Ethiopian Rift Valley lakes have been subjected to environmental and ecological changes due to recent development endeavors and natural phenomena, which are visible in the alterations to the quality and quantity of the water resources. Monitoring lakes for temporal and spatial alterations has become a valuable indicator of environmental change. In this regard, hydrographic information has a paramount importance. The first extensive hydrographic survey of Lake Hawassa was conducted in 1999. In this study, a bathymetric map was prepared using advances in global positioning systems, portable sonar sounder technology, geostatistics, remote sensing and geographic information system (GIS) software analysis tools with the aim of detecting morphometric changes. Results showed that the surface area of Lake Hawassa increased by 7.5% in 1999 and 3.2% in 2011 from that of 1985. Water volume decreased by 17% between 1999 and 2011. Silt accumulated over more than 50% of the bed surface has caused a 4% loss of the lake's storage capacity. The sedimentation patterns identified may have been strongly impacted by anthropogenic activities including urbanization and farming practices located on the northern, eastern and western sides of the lake watershed. The study demonstrated this geostatistical modeling approach to be a rapid and cost-effective method for bathymetric mapping.

Assessing the Water Quality of Lake Hawassa Ethiopia—Trophic State and Suitability for Anthropogenic Uses—Applying Common Water Quality Indices

“…The mean minimum precipitation is 17.8 mm in December (dry season) and the mean maximum precipitation is 119.8 mm in August (rainy season) [33]. The long-term mean annual temperature is around 19 • C while the mean monthly evapotranspiration in the low lands ranges from 39 mm in July to 100 mm in January [34].…”

Hide and seek: management and landscape factors affecting maize stemborers Busseola fusca (Fuller) infestation levels in Ethiopia

“…Farmers reported that attacks on their maize fields by baboons was one of the reasons they decreased maize production. The decrease in water availability has been reported by previous studies which investigated the effect of land cover/land use change on the hydraulic regime and water volume of Lake Hawassa (Shewangizaw, 2010;Abebe et al, 2018). A remarkable feature on the land classification map ( Fig.…”

Object‐based image analysis (OBIA)‐based gully erosion dynamics, sediment loading rate and sediment yield study in Lake Hawassa Sub‐basin, Ethiopia

“…Many lakes, including man‐made reservoirs, are losing a significant portion of their original storage capacity due to sedimentation caused by water erosion in their watersheds (Abdallah, 2012; Abebe et al, 2018; Aga et al, 2019; Belete et al, 2021). Studies have shown that 1%–2% of the world's available storage capacity is lost to sedimentation each year (Asselman, 2000).…”

“…Lake Hawassa lost about 4% of its storage capacity in between 1999 and 2011 (Abebe et al, 2018) due to sedimentation. In addition to this, a considerable portion of the Lake's catchments are having under extensive gully erosion (Belete, 2013; Belete et al, 2021; Hoogenbooh, 2013; Moges & Holden, 2008).…”