A GIS-Based Hydraulic Bulking Factor Map for New Mexico

In this study, sediment loading and clogging potential were evaluated based on a physiographic and hydrologic perspective for eight small semi-arid watersheds within New Mexico. Attributes related to drainage and sediment load were characterized using an ArcGIS® software-based approach. An in-depth terrain analysis coupled with land cover, precipitation, soil, and hydrography raster datasets provided characterization of key watershed attributes. Associated raster maps of derived attributes were generated in addition to watershed peak flow and runoff. With this composite data a bulking factor, or ratio of total flow with sediments to clean water flow, was estimated. For engineering design, the bulking factor provides for an increased hydraulic capacity for culvert sizing under sediment load. Significant trends and correlations were evident and supported by literature, thus offering the potential for the development and verification of a statewide bulking factor map and ultimately an engineering design factor for drainage structures.