Forest cover change over four decades in the Blue Nile Basin, Ethiopia: comparison of three watersheds
The objective of this study was to quantify forest cover changes in three watersheds (Gilgel Abbay (1,646� km²), Birr (980� km²), and Upper-Didesa (1,980� km²) of the Blue Nile Basin between 1957 and 2001. Four land cover maps were produced for each watershed for 1957/1958, 1975, 1986, and 2000/2001. Nine different types of land cover were identified, five of which were forest cover classes. Between 1957 and 2001, the total forest cover increased in Gilgel Abbay (from 10 to 22� % cover) and decreased in Birr (from 29 to 22� % cover) as well as in Upper-Didesa (from 89 to 45� % cover).