GIS-Based Hydraulic Bulking Factor Map for New Mexico

In this study, hydraulic bulking was evaluated based on a physiographic and hydrologic perspective of eight small semiarid watersheds within New Mexico. Attributes related to drainage and sediment load were characterized using an ArcGIS (Esri, Redlands California) approach. An in-depth terrain analysis coupled with land cover, precipitation, soil, and hydrography raster data sets provided characterization of key watershed attributes. Associated raster maps of derived attributes were generated, in addition to watershed peak flow and runoff volume based on a 100-year, 24-h precipitation. With this composite data, a hydraulic bulking factor, or ratio of total flow with sediments to clean water flow, was estimated. Bulking factors ranged from 1.01 to 1.65. Significant trends and correlations were evident and supported by literature, thus offering the potential for development of a statewide bulking factor map and ultimately an engineering design factor for drainage structures. A procedure for estimating this bulking factor is presented; however, field verification of the proposed methodology is needed.