Three Decades of Road and Trail Runoff andErosion Work in the Northeastern Caribbean –a Research Program Perspective

Highlights The infiltration capacities of unsurfaced roadways are frequently exceeded by rain intensity, promoting overland flow. Erosion rates from and cut slopes 10 1 to 4 times greater than on undisturbed hillslopes. Roads in steep, subtropical wet terranes may increase landslide erosion a factor 5 relative areas without roads. hydro-geomorphic impact roads is so prominent that they must be explicitly considered watershed assessments. ABSTRACT. key environmental concern the northeastern Caribbean because it can diminish soil productivity, damage infrastructure, threaten human life. Additionally, sediment released delivered streams where degrade water quality aquatic habitat, reduce reservoir storage capacity, critical marine resources such as sea grass beds coral reefs. Road has been region since 1990s, considerable body research conducted over last ~30 years. This article reviews findings identifies additional needs. In some tropical dry coastal watersheds US Virgin Islands Puerto Rico, unpaved foot or off-road vehicle trails primary sources. Watershed scale production these settings 0.3 3.7 Mg ha-1 yr-1, depending road density, 3 40 under conditions. wetter settings, like forested actively cultivated landscapes highland contributions include those farm but also croplands, streambanks, landslides. 15 60 with road-induced surface landslides accounting for 50% 95% total production. Designing management alternatives will require improve our understanding road-to-stream road-to-coast connectivity, develop effectiveness metrics applied practices, establish specific causes Keywords: Connectivity, Coral reefs, Landslides, Sedimentation, Surface erosion, Islands.