Hydrodynamic Modeling in Hodges Reservoir


Heads-up digitizing of a 2-D contour map of Hodges Reservoir to a triangulated irregular network (TIN).

hodges_CEQUAL Hodges Reservoir represented as a triangulated irregular network (TIN) and bathymetric input file for CE-QUAL-W2.

temp_profiles_1995
Observed (1995) and modeled (2050) vertical temperature profiles using projections of future climate change according to global climate models.

PROJECT TITLE: Modeling Hydrodynamics in a Shallow Hypereutrophic Reservoir

SPONSOR: Edna Bailey Sussman Foundation

PROJECT DURATION: 1 September 2011 to 30 April 2014

PRINCIPAL INVESTIGATORS: Raymond Lee, Trent Biggs

PROJECT SUMMARY: Reservoir water quality is strongly impacted by thermal and hydrodynamic regimes, which in turn are controlled by climate. Higher air temperatures can increase surface water temperature and evaporative loss, leading to a shift in hydrodynamic regime to either increased stability and an attendant increase in the release of phosphorus from sediment or to decreased stability and possibly an attendant increased vertical transport of phosphorus to the photic zone. We tested the effects of future climate warming on temperature and stability in a shallow, hypereutrophic reservoir, by calibrating a 2-D model (CE-QUAL-W2) of reservoir hydrodynamics using a long term (1990–2011) reservoir inflow and temperature data set, then forced projections of increased air temperature. The projections were spatially and temporally explicit, accounting for complex local topography and Mediterranean seasonality, with greater warming in summer. The model successfully mimicked evaporation, surface water level, and temperature. Temperature increased in the whole-reservoir, epilimnion, and hypolimnion and was highly correlated with air temperature. Water temperature increased linearly and significantly with projections of climate projections by an average of 0.30 (whole-reservoir), 0.37 (epilimnion), and 0.35 °C (hypolimnion) per 1 °C increase in summer air temperature. Warming was greater in the hypolimnion in all climate projections, which led to a slight decrease in stability and an earlier breakdown of summer stratification. Model results suggest that future increases in air temperature may lead to increased entrainment of phosphorus during the peak algal growing season and degradation of water quality.

PUBLICATIONS:

Lee, R. M. and T. W. Biggs. Warmer thermal regimes under a warmer climate in a shallow hypereutrophic reservoir. In prep.

Lee, R. M. and T. W. Biggs. Simulation of oxygen depletion, sediment nutrient release, and nutrient circulation under a warmer climate in a shallow hypereutrophic reservoir. In prep.

LINKS:

San Diego Water Department