INCORPORATING ROADS AND FOOTPATHS IN WATERSHED-SCALE HYDROLOGIC AND SOIL-EROSION MODELS

Hydrologic and soil erosion models, even distributed models, require some degree of generalization of land surface characteristics. Because generalization typically depends on the areal extent of parameter values, surfaces that affect geomorphic/erosional processes out of proportion to their areal extent require special consideration. Increased erosion and sediment yield on roads and trails is frequently reported, but the interactive process relationships between such highly compacted and neighboring, less compacted surfaces have received little research attention. This paper reviews watershed-scale modeling strategies and presents the results of rainfall simulation experiments conducted on paired path and non-path sites in highland Ecuador and East Tennessee. The results show rural roads and footpaths to be the most active runoff-generating components of inhabited mountain landscapes and provide preliminary quantitative and qualitative bases for incorporating the runoff and erosion-initiating effects of rural roads and paths in watershed models.