Two‐zone transient storage modeling using temperature and solute data with multiobjective calibration: 1. Temperature

Abstract

This paper presents the formulation and calibration of the temperature portion of a two‐zone temperature and solute (TZTS) model which separates transient storage into surface (STS) and subsurface transient storage (HTS) zones. The inclusion of temperature required the TZTS model formulation to differ somewhat from past transient storage models in order to accommodate terms associated with heat transfer. These include surface heat fluxes in the main channel (MC) and STS, heat and mass exchange between the STS and MC, heat and mass exchange between the HTS and MC, and heat exchange due to bed and deeper ground conduction. To estimate the additional parameters associated with a two‐zone model, a data collection effort was conducted to provide temperature time series within each zone. Both single‐objective and multiobjective calibration algorithms were then linked to the TZTS model to assist in parameter estimation. Single‐objective calibrations based on MC temperatures at two different locations along the study reach provided reasonable predictions in the MC and STS. The HTS temperatures, however, were typically poorly estimated. The two‐objective calibration using MC temperatures simultaneously at two locations illustrated that the TZTS model accurately predicts temperatures observed in MC, STS, and HTS zones, including those not used in the calibration. These results suggest that multiple data sets representing different characteristics of the system should be used when calibrating complex in‐stream models.