MODELING SAN JOAQUIN RIVER FLOW PATH ALTERATIONS FOR RESTORATION PROJECT

The San Joaquin River (SJR) is one of the most vital natural resources to the residents and industries within central California. Along with human necessities, the river is crucial for the propagation and survivability of Chinook salmon and other aquatic and wildlife. However, Indigenous salmon populations have been degraded over the years due to insufficient flows and anthropogenic activities. Many water resources management operations such as dam construction, gravel extraction, and water diversion have altered the flow current and water stage of the SJR, resulting unfavorable living conditions for salmon. Currently, the SJR is undergoing a major evaluation by state and federal agencies as part of a legal settlement. In 2006, the San Joaquin River Restoration Project (SJRRP) was established with different alternative plans to restore flows to the SJR from Friant dam to the confluence of the Merced River. The salmon population is expected to be sustainable by restoring adequate flow to the subjected area through the project.

The objective of the research project is to characterize the stream conditions of each proposed alternative of SJRRP using a modeling method. By simulating and predicting flow conditions of each alternative, this project may offer an insightful understanding of the hydrodynamic occurrence of river alterations and aid in the best passage for Chinook salmon. In this research, a two-dimensional mathematic model is developed to simulate the hydrodynamic conditions (e.g., current velocity, water surface elevation, etc.) of different alternatives, incorporating the disengaged portion of the SJR along the current path proposed in the SJRRP. The 2-D model will facilitate model flow features which are essential to the SJRRP. Flow simulation will allow for the exploration of flow patterns and enable the user to compare each alternative. The research domain extends from Sack Dam to Highway 140, downstream of the Salt Slough confluence. In this area, a portion of the SJR’s flow has been diverted and presently courses through an engineered bypass, excluding flow from entering an original stretch of the SJR. SMS11.0 (Surface water Modeling System) and finite element models RMA2 and RMA10 are used in the model development.