One- and Two-Dimensional Modeling of Deep Gravel Mining in the Rio Salado

Impact of deep sand and gravel mining pits (with a depth of 10 meters) on flood zone coverage and riverbed change of the Rio Salado, Salt River, Phoenix, Arizona were simulated using one- and two-dimensional numerical models. Two commonly used models are applied in the study, i.e., HEC-RAS and CCHE2D. HEC-RAS is a one-dimensional hydrodynamic and sediment transport model developed by the U.S. Army Corps of Engineers, while CCHE2D is a depth-averaged two-dimensional hydrodynamic and sediment transport model developed at the University of Mississippi. The bed material was treated as three layers on the channel bed with multiple grain-sized sediment mixtures. Changes in bed elevation were calculated by solving the sediment mass conservation equation. The modeling results of CCHE2D were compared with the HEC-RAS modeling results and field observations, which showed that the 2D model was more robust in simulating flood zone coverage, non-uniform sediment sorting, and channel geomorphologic changes.