Title

Monitoring and Calibration of a Three-Dimensional Hydrodynamic Model for Lake Arrowhead, California, Prior to Initiating Indirect Potable Reuse Through Surface Water Augmentation,

Document Type

Conference Proceeding

Publication Date

11-14-2019

Publication Title

39th International Symposium of the North American Lake Management Society

Publisher

American Society of Civil Engineers

First page number:

1

Last page number:

1

Abstract

A multi-year monitoring and modeling effort was conducted to evaluate lake mixing and transport processes prior to planning for surface water augmentation at Lake Arrowhead, California, a warm climate high-altitude lake. Data from a wide range of instrumentation including, multiparameter water quality profiles, four weather stations, two acoustic Doppler profilers, six Lagrangian drifters, and two thermistor strings, combined with utility water withdrawals and high-resolution bathymetry were used to calibrate the hydrodynamic model. If approved, an extensively researched non-toxic dye tracer will be used to validate the model. Findings to support model calibration include: Lake level varied 3.2 meters during the study period. Water inflows occurred primarily during winter storms. Mixing and transport were primarily wind driven. Small differences in water quality indicators were found across the lake’s four major bays. Lake stratification began in late February, peaked in July and ended with December overturn. Hypolimnetic hypoxia below 4 mg/L occurred during stratification. Reoxygenation rapidly occurred following turnover. Mountainous terrain generated a spatially variable wind field, with slower southwesterly prevailing wind speeds near the south shore and higher southerly and southeasterly wind speeds on the north shore. The calibrated AEM3D hydrodynamic model, simulating one year on a 30 × 30 × 0.5 meter grid, successfully reproduced the lake’s energy and water balances and its temperature profiles. Correlations of water column velocity profiles and prevailing winds were investigated and subsequently used to estimate water column mixing intensity. ADP and Lagrangian drifter data were used to validate velocity profiles.

Keywords

Lake mixing; Surface water augmentation; Lake Arrowhead; Hydrodynamic model

Disciplines

Earth Sciences | Hydrology | Physical Sciences and Mathematics

Language

English


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