Observed and model simulated twenty-first century hydro-climatic change of Northern Ethiopia

Samuale Tesfaye, Gebeyehu Taye, Emiru Birhane, Sjoerd EATM van der Zee

Journal of Hydrology Regional Studies · 01 March 2019

In one sentence. ANNs downscale 30 CMIP5 GCMs for the Tekeze basin, projecting falling precipitation and streamflow to 2099 under RCP4.5 and RCP8.5, with multi-model ensembles more robust.

Abstract

• Temperature, precipitation and streamflow changes are projected using ANNs model informed by 30 CMIP5 GCMs. • Tekeze river basin exhibits high spatiotemporal observed streamflow variability. • Climate models show limited performance in precipitation and streamflow simulation. • Projection exhibits decrease of precipitation and streamflow in the Tekeze river basin. • It is best to use multi-GCMs to provide additional and more robust evidences in projection. This study focuses on Tekeze river basin of northern Ethiopia, and it is characterized by a typical dry biogeophysical environment. In recent years, recurrent droughts are having an adverse impact on agricultural production and water resources in northern Ethiopia. Climate change through changes on temperature, precipitation and streamflow, may further strain this critical situation. This study has investigated the observed (1961–2014) and potential (2006–2099) hydro-climatic changes in Tekeze river basin of northern Ethiopia. Artificial Neural Networks (ANNs) are used to downscale temperature and precipitation predicated by 30 General Circulation Models (GCMs) as well as the projected streamflow changes for two Representative Concentration Pathways (RCP4.5 and RCP8.5) scenario. Results indicate that the variability of climatic factors as temperature and precipitation was observed to be both spatially and temporally diverse for the considered Tekeze river basin. Accordingly, the response of streamflow was also spatiotemporally complex. GCMs were evaluated with several performance indictors regarding patterns in hydro-climatic variables. The analysis showed the superiority of the multimodel ensemble means compared with individual GCM output. GCM projections for the 21century indicate a gradual reductions in streamflow attributed to the combined effect of increasing temperature and decreasing precipitation. The persistent increase of temperature and decrease of precipitation will have negative impacts on water availability and agriculture, hence site specific adaptation strategies are necessary.

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