Gis & Rs Based Analysis Of Land Use/Cover Dynamics In Gilgel Gibe_1 Dam Sub- Catchiment, Jimma Zone,

Abstract

This study was intended to investigate the trend of land use /land cover dynamics in Gilgel Gibe-1 sub-catchment for the last 29years (1986-2015.) For the selected study years 1986, 2000 and 2015 three-time series satellite images TM, ETM+ and OLI were used respectively. Additionally, socio-economic assessment was conducted by using KII and FGD to investigate the driving forces of land use land cover change. The study covers a total area of 168,857.91 ha. Five land use/ land cover classes namely; farmland, forest, grassland, water body and builtup were clearly identified for the study. The result reported that in the first period, 1986-2000 forest and grassland showed decreasing trend by 37.44% and 1.95%, respectively. But farmland and water body showed increment at the same time by 42.35% and 7.65% respectively. In the second study period farmland, waterbody, built-up and grassland were decreased by 14.83% ,13.07%,15.84% and 6.48% respectively. Forestland showed increment by 49.78%, In the entire period of the study forest, built-up and grass land were decreased by 14.07%, 28.08 and 8.02%, respectively. The extent of deforestation was very high during the second study period. In 1986, the largest area was covered by forest land and small area by water body, which constituted 41.7% (70,345.08ha) and 3.4% (5791.27ha), respectively. The farmland, built-up and grassland covered 14.7 %( 24529.68ha), 29.3%( 49796.64ha) and 10.9%(18390ha respectively. The land use/ land cover classification for the year 2000, as a year of 1986, the largest area was covered by farm land and small area by waterbody which accounts for 44.8 %( 75,648.34 ha) and 8.9 %( 15,028ha), respectively. Built-up, forest and grassland were accounted 21.9 %(36,979.88ha), 14.9%(25059 ha), and 9.5 %( 16,041.50ha), respectively. In the final classification year (2015) land use land cover classification analysis of the study showed that farmland 38.9%( 65685.72ha), water body 3.7% (6247.74ha), forest 34.7% (58593.69ha), grassland 9.5% (16041.50ha) and built-up 15.6%( 26341ha) respectively. It was different from the first and second classification years, the farmland was 38.9 %( 65,685ha) and dominant classes of the area. Therefore, to solve the forest cover shrink; effective and strong natural vegetation management and utilization policy have to be implemented by districts forest office and the regional government to insure the sustainability of natural resources by protecting natural forest with the participation of local community.