Social and Ecological System Dynamics

Abstract

Lake Tana Basin is the second largest sub-basin of the Blue Nile which covers an area of 15,114 km(2). Lake Tana is a tropical Lake with surface area of 3111 Km(2). It is the largest fresh water resource of Ethiopia (50%). It is the source of the Blue Nile(Abay) River. Lake Tana basin and Blue Nile river provide economic, social, political, environmental, ecological and religious benefits also for downstream eastern Nile countries. The basin problems have also influence in downstream eastern Nile countries. Food security and environmental sustainability are grand challenges in the basin. Ensuring adequate supply and quality of water for water user sectors in the basin remains a challenge. The sanitation and hygiene coverage remains not significantly improved compared to the unprecedented population growth. The basin suffers from easily perceivable land, soil and water degradation which are manifested in different forms: Sedimentation, clearing of wetland, canalization of the tributaries, increased trend of eutrophication, toxigenic cyano bacteria, occurrence of invasive species like water hyacinth (Eichornia crassipes), stakeholders conflict, improper damming, construction of buildings in the Lake shore areas that are natural breeding and feeding grounds for somefish and bird species, poorwastemanagement, increased prevalence of waterborne diseases especially in the riparian community which largely depend on raw water for drinking and recreation aremajor problems of theBasin. Climate change is also having its impact. Though the problems and challenges are known in the area, effective measures proportion to the magnitude of the problem are not yet taken sufficiently.