Hydrological responses to land use/land cover change and climate variability in contrasting agro-ecological environments of the Upper Blue Nile basin, Ethiopia

Mulatu Liyew Berihun; Atsushi Tsunekawa; Nigussie Haregeweyn; Derege Tsegaye Meshesha; Enyew Adgo; Mitsuru Tsubo; Tsugiyuki Masunaga; Ayele Almaw Fenta; Dagnenet Sultan; Mesenbet Yibeltal; Kindiye Ebabu

doi:10.1016/j.scitotenv.2019.06.338

Hydrological responses to land use/land cover change and climate variability in contrasting agro-ecological environments of the Upper Blue Nile basin, Ethiopia

Sci Total Environ. 2019 Nov 1:689:347-365. doi: 10.1016/j.scitotenv.2019.06.338. Epub 2019 Jun 27.

Affiliations

¹ The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia. Electronic address: mulatuliyew@yahoo.com.
² Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori 680-0001, Japan.
³ International Platform for Dryland Research and Education, Tottori University, 1390 Hamasaka, Tottori 680-0001, Japan.
⁴ College of Agriculture and Environmental Sciences, Bahir Dar University, P.O. Box 1289, Bahir Dar, Ethiopia.
⁵ Faculty of Life and Environmental Science, Shimane University, Shimane, Matsue 690-0823, Japan.
⁶ Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia.
⁷ The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia.
⁸ The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; College of Agriculture and Environmental Sciences, Bahir Dar University, P.O. Box 1289, Bahir Dar, Ethiopia.

PMID: 31277003
DOI: 10.1016/j.scitotenv.2019.06.338

Abstract

Land use/land cover (LULC) change and climate variability are two major factors controlling hydrological responses. The present study analyzed the separate and combined effects of these two factors on annual surface runoff and evapotranspiration (ET) after validating the selected models in three drought-prone watersheds of the Upper Blue Nile basin: Kasiry (highland), Kecha (midland), and Sahi (lowland). LULC maps were produced from aerial photographs and very-high-resolution satellite images from 1982, 2005/06 and 2016/17. During 1982-2016/17 the area covered by natural vegetation showed dramatic decreases, ranging from 60.2% in Kasiry to 51.8% in Sahi. In contrast, increases in cultivated land ranged from 36.7% in Kasiry to 279.6% in Sahi; the smaller increase in Kasiry resulted from the conversion of a portion of the cultivated land to an Acacia decurrens plantation after 2006. The observed LULC changes over the study period resulted in runoff increases ranging from 4% in Kecha to 28.7% in Kasiry. Climate variability in terms of annual rainfall had no significant effect on estimated runoff; whereas both LULC change and climate variability had significant effect on estimated ET. Though climate variability increased ET from 33.6% in Kecha to 42.1% in Kasiry, the LULC change related to the reduction in natural vegetation had an offsetting effect, which led to overall decreases in ET ranging from 15.8% in Kasiry to 32.8% in Kecha watershed. As changes in LULC and climate are expected to intensify in the future, it is important to study further hydrological responses considering these changes to devise future sustainable land and water management strategies.

Keywords: Drought-prone; Evapotranspiration; High-resolution satellite images; Surface runoff; Sustainable land management.

MeSH terms

Agriculture*
Climate Change*
Conservation of Natural Resources*
Ethiopia
Forests*
Hydrology
Water Movements*