Spatial coverage of water hyacinth (Eichhornia crassipes (Mart.) Solms) on Lake Tana and associated water loss

Abstract

The introduction of water hyacinth poses a serious threat to economic viability of Lake Tana and its environments. This study aimed to capture the spatial coverage of water hyacinth and its effect on water loss in Lake Tana using quantitative research methods. Four satellite images representing each season of 2019 were downloaded from USGS. In addition, pan evaporation data were taken from the National Meteorological Agency. ArcGis 10.4, Envi 5.3, Qgis 3.12.1 plug in CSP and Excel used to manage land use land cover classification and water loss estimation analysis. The seasonal coverage of water hyacinth was 15.35, 4.14, 11.82 and 13.59 km2 in winter, autumn, summer and spring 2019 respectively representing 0.63 and 0.17 percent of the Lake as a maximum and minimum coverage. The mean daily evaporation of Lake Tana was 5.14 mm/day, but this increased to 18.85 mm/day due to the presence of water hyacinth. The mean net daily water loss due to water hyacinth at Lake Tana was 0.14 km2 while 52,62 km3 in 2019. The study concludes that water hyacinth caused enormous negative impact on the water volume reduction in Lake Tana. Management of the Lake Tana environment and control of the water hyacinth weed are recommended to sustain the Lake.