Giving greater consideration to cross-drainage discharge from forest roads

Erosion below the outlets of cross drains (e.g., culverts'and broad-based dips) on forest roads in the central Appalachians is common but controllable. Erosion control below cross drains must take the form of reduced water discharged through each cross-drainage structure, slowed release of water, and/or adequate roughness for energy dissipation and water infiltration. Water released through cross drains is the contribution fiom the roadbed and the hillslope above, so the size and hydrologic characteristics of the contributing area and cutbank (on cut and-fill roads) should be considered with road grade when locating cross drainage structures. Roughness traditionally has taken the form of grass planting on the fillslopes, check dams below cross drains, and/or placement of native rock or riprap below outfalls. But often these methods are ineffective because they are installed or applied incorrectly. Every state's best management practices (BMPs) discuss the need to control cross drainage erosion, yet this problem is all too common. We need improved technology transfer to relay the importance of cross-drain discharge control. Additional work also is needed to develop new cross-drainage techniques for erosion control and possibly adapt techniques used in the construction and engineering trades; for example, brush layering, using riprap or native rock with interplantings or cuttings, and securing biodegradable geotextiles on fillslopes in forested areas to reduce erosion and sediment transport to streams.