Modeling the impact of climate change on the environmental flow indicators over Omo-Gibe basin, Ethiopia

The study focuses on climate change impacts on the environmental flow indicators from hydrologic method point of view using IWMI's Global Environmental Flow Calculator and Indicators of Hydrologic Alteration. It also discusses how the changes in flow magnitude and duration of annual extreme conditions, timing of annual extreme water condition, frequency and duration of high and low pulses, rate and frequency of water condition changes will affect the ecosystem. Climate change disturbs the ecology by directly affecting the functions of individual organisms (growth and behavior), modifying the population (size and age structure), and altering the ecosystem structure, functioning (e.g., decomposition, nutrient cycling, water flows, and species composition and species interactions) and its distribution within landscapes (Gitay et al., 2002). Ecosystem regime shifts can occur naturally and by anthropogenic factors (Muenich et al. in Ecol Model 340:116-125, 2016). Climate change effects on flow regime are expressed by different indicators such as mean annual runoff, mean river discharge, low and high flows, mean seasonal discharge, and changes from permanent to intermittent flow or vice versa. Understanding of changes in flow regimes is important for the well-being of humans and freshwater-dependent biota with respect to water and habitat availability (Doll and Schmied in Environ Res Lett 7(1):14037, 2012). Even though the basin is rich in fish species, peoples living in lower Omo-Gibe basin and Turkana region are undertaking a traditional fishing culture. Wildlife in the parks, pastoralist communities using the flood recession farming and livestock farming are dependent on the river. The environmental flow that sustains these activities is inevitably necessary for the survival of the biodiversity. Understanding of the flow variability helps to protect the freshwater biodiversity and maintenance of goods and services that the river provides.