Changes in landuse patterns in upland watersheds of Eastern Luangwa Valley, Zambia, and the potential impact on runoff and erosion
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Four small watersheds, Kamwamphula, Luelo, Kanyanga and Mphiri, near Emusa (Lundazi District) in Eastern Province, Zambia, were studied to document transitions in land use over time and to project the impacts of land use and topography on runoff, erosion and sediment delivery. Land use was delineated from 2007 IKONOS image (one meter pixel), and Landsat imagery was used to depict the historic changes in lands between the period of 1989 and 2007. The GWLF model was used to predict the impact of the laundress on the hydrology of the area. There has been an increase in clearing of forest area mainly due to the expansion of cropland area. The highest rate of clearing was predicted for the Kamwamphula watershed where the forest cover decreased from 95% to 71% over the 18 year period. The GWLF model was used to predict the impact of the lands on the hydrology and sediment delivery. In comparison with the limited field data available from the four watersheds, the GWLF model gave poor prediction of streamflow, probably because the hydrology of the area is poorly understood and dambo function in the landscape is not well represented in the model. Highest runoff, erosion and sediment yields came from Luelo watershed which has steeper slopes and less vegetative cover and poor permeability of soils.