(Erosion Prediction in Ungauged Basins: Integrating Methods and Techniques (Proceedings of Symposium HS01 held during IUGG2003 at Sapporo, July 2003), IAHS Publication No. 279, 2003, pp. 216–223).
We investigate the degree to which the current juxtaposition of land cover in a fragmented basin in northern Vietnam mitigates the impacts of accelerated overland flow by buffering surface runoff generated on upslope source areas. Our methodology utilizes: (a) field measurements of infiltration-related soil properties, especially saturated hydraulic conductivity (KS); (b) minute-by-minute rainfall data; (c) GIS analyses of land-cover distribution and flow-transitions between 30 x 30 m grid cells of major basin land covers; and (d) diagnostic simulations of overland flow generation using KINEROS2. We compare simulated basin-wide Horton overland flow (BWHOF) for the current land cover arrangement with that of three fragmentation scenarios; maximum buffering, minimum buffering, and random distribution of land-cover grid cells. The comparisons show that buffering opportunities for the current land-cover distribution are in between maximum and minimum buffering scenarios, and there are fewer buffering opportunities than for the situation where grid cells are distributed at random (i.e. a scenario representing a higher degree of fragmentation). The analyses support the idea that surface erosion and sediment delivery could be mitigated further if land covers having high KS were positioned intentionally below overland flow sources.
Forest fragmentation, KINEROS2, Overland flow, Southeast Asia, Vietnam
