Comparison of modelling techniques to predict macroinvertebrate community composition in rivers of Ethiopia

Abstract

In order to fulfil the millennium development goals and to ensure environmental sustainability in Ethiopia, ecological indicator systems can support river managers to analyse the status of watercourses and to select critical restoration actions. In order to use macroinvertebrates as river water quality monitoring and assessment tools, Ethiopia needs data from reference as well as disturbed conditions of surface water ecosystems. Macroinvertebrates, structural and physical–chemical data were in this context collected in the Gilgel Gibe river basin in South-Western Ethiopia during the period 2005–2008. In the next stage, ecological metrics were compared for their assessment relevance. In the present paper, classification trees and support vector machines were used to induce models describing the relation between the river characteristics and the ecological conditions of these streams. Greedy stepwise and genetic search algorithms improved the performance and easy interpretation of these models by making a selection of the variables that were used as input of these models. The developed models allowed to identify the major variables affecting river quality. These tools can support river managers in their decision-making regarding the status of rivers and potential restoration options, for example by providing rules concerning critical values of major river characteristics at which certain actions should be undertaken.