Water Hyacinth in the Rift Valley Water Bodies of Ethiopia: Its Distribution, Socioeconomic Importance and Management

Abstract

A survey was conducted in the Rift Valley water bodies of Ethiopia from 2009 to 2011 to (i) determine the prevalence, agro-ecological distribution and sources of infestation of water hyacinth, (ii) investigate the socio-economic impact of water hyacinth, and (iii) assess changes in its agro-ecological distribution. Water hyacinth was first introduced into the Rift Valley water bodies as an ornamental plant in the 1950s around the Aba-Samuel Dam. Eventually, it spread into Lake Koka, Lake Ellen, Koka Dam and Wonji site via the Awash River. Now it is common in various water bodies located at low, mid and high altitudes. At Lake Koka, Lake Ellen, Aba-Samuel Dam and Koka Dam, an increase in water cover was observed during the study period. Univariate as well as PCA analysis indicated that rainfall, intensity of wave action on the water bodies, water depth, N and P content of the water bodies were the factors representing the majority of correlations with water hyacinth coverage. Interviews revealed that the weed mats had an adverse socioeconomic impact on the local communities and enterprises. The present assessment also noted that no major management strategy had been employed in the infested water bodies except at Wonji and Koka Dam where a significant reduction (i.e., <7% distribution) has been achieved. On the contrary, increasing trend of water hyacinth invasion had been observed in the upstream water bodies. Hence, effective management strategy should be implemented in the upstream water bodies so as sustain achievements in Wonji