Climatic controls of ecohydrological responses in the highlands of northern Ethiopia Samuale Tesfaye a,b, ⁎, Emiru Birhane b,c , Toon Leijnse a , S.E.A.T.M. van der Zee a,d a Soil Physics and Land Management Group, Wageningen University, P.O. Box 47, 6700 AA, The Netherlands b Department of Land Resources Management and Environmental Protection, Mekelle University, Ethiopia c Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, No-1432 Ås, Norway d School of Chemistry, Monash University, Melbourne, VIC 3800, Australia HIGHLIGHTS • Trends and relationships of climatic var- iables, streamflow and NPP were exam- ined. • Streamflow trends are different in dif- ferent sub-catchment at different time- scale. • NPP exhibits significant positive inter- annual and seasonal trends. • Precipitation and maximum tempera- ture were the more dominant climatic variables. • Human intervention has a profound ef- fect on streamflow and NPP variation. GRAPHICAL ABSTRACT abstract article info Article history: Received 13 January 2017 Received in revised form 15 July 2017 Accepted 15 July 2017 Available online xxxx Editor: D. Barcelo Climate variability and recurrent droughts have a strong negative impact on agricultural production and hydrology in the highlands northern Ethiopia. Since the 1980s, numerous mitigation and land rehabilitation measures have been implemented by local and national authorities to reduce these impacts, are often poorly effective. As under- lying reason may be that controlling relationships between climate and ecohydrology at medium-sized catch- ments (10–10,000 km 2 ) of semi-arid highlands are not well known. We investigated trends and relationships in precipitation, temperature, streamflow, and net primary productivity (NPP). The results were mixed, with both significant increasing and decreasing trends for temperature and streamflow. Precipitation time series did not show a significant trend for the majority of stations, both over the years and over each season, except for a few sta- tions. A time series indicated a significant abrupt increase of NPP in annual, seasonal and monthly timescale. Cross- correlation and regression analysis indicate precipitation and maximum temperature were the dominant climatic variables in the Geba catchment for streamflow and NPP. In view of these results, also land use and land cover change over the past three decades was analysed as a possible factor of importance, as human intervention, may affect streamflow and NPP. Factors that mainly correlate with streamflow and NPP are precipitation and maximum temperature. Important interventions that appear beneficial for these responses are construction of micro-dams, soil and water conservation and ecological restoration measures. The awareness that interactions can be quite dif- ferent in semi-arid and semi-humid regions, as well as in upstream and downstream areas, should be reflected in management aimed at sustainable water and land resources use. © 2017 Elsevier B.V. All rights reserved. Keywords: Precipitation Streamflow Primary productivity Ecosystem model Land use Semi-arid Science of the Total Environment 609 (2017) 77–91 ⁎ Corresponding author at: Soil Physics and Land Management Group, Wageningen University, P.O. Box 47, 6700 AA, The Netherlands. E-mail address: samuale.tesfayebaye@wur.nl (S. Tesfaye). http://dx.doi.org/10.1016/j.scitotenv.2017.07.138 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv