A General Lake Model (GLM 3.0) for linking with high-frequency sensor data from the Global Lake Ecological Observatory Network (GLEON)

Abstract

Abstract. The General Lake Model (GLM) is a one-dimensional open-source code designed to simulate the hydrodynamics of lakes, reservoirs, and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of researchers using sensors to understand lake functioning and address questions about how lakes around the world respond to climate and land use change. The scale and diversity of lake types, locations, and sizes, and the expanding observational datasets created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management questions relevant to the GLEON community. This paper summarizes the scientific basis and numerical implementation of the model algorithms, including details of sub-models that simulate surface heat exchange and ice cover dynamics, vertical mixing, and inflow–outflow dynamics. We demonstrate the suitability of the model for different lake types that vary substantially in their morphology, hydrology, and climatic conditions. GLM supports a dynamic coupling with biogeochemical and ecological modelling libraries for integrated simulations of water quality and ecosystem health, and options for integration with other environmental models are outlined. Finally, we discuss utilities for the analysis of model outputs and uncertainty assessments, model operation within a distributed cloud-computing environment, and as a tool to support the learning of network participants.

A near-term iterative forecasting system successfully predicts reservoir hydrodynamics and partitions uncertainty in real time

“…FLARE simulated reservoir hydrodynamics with the General Lake Model (GLM), a one-dimensional (1-D) vertical stratification model [ Hipsey et al 2019 ]. We used GLM because: 1) the model has successfully reproduced observed water temperature profiles in lakes around the world with varying mixing regime, climate, and morphology [ Bruce et al 2018 ]; 2) GLM is an open-source, community-developed model and thus scalable to other waterbodies for future forecasting applications [ Snortheim et al 2017 ]; and 3) GLM has low computational needs, enabling many model ensemble members to be run quickly and efficiently, a requirement for near-term iterative forecasting.…”

“…To enable generalization to other lakes or reservoirs, we set all but three highly sensitive parameter values equal to the values reported in the default GLM version 3.0 model [ Hipsey et al 2019 ]. The three parameters, selected using the methods described in Supplemental Information A), were: a scalar for incoming shortwave radiation (sw_factor) and two parameters defining the sediment temperature in the deep and shallow reservoir zones (zone1temp: 5 – 9.3 m deep; zone2temp: 0 – 5 m deep).…”

“…The three parameters, selected using the methods described in Supplemental Information A), were: a scalar for incoming shortwave radiation (sw_factor) and two parameters defining the sediment temperature in the deep and shallow reservoir zones (zone1temp: 5 – 9.3 m deep; zone2temp: 0 – 5 m deep). For driver data, GLM requires hourly meteorological data on downwelling shortwave radiation (W m -2 ), downwelling longwave radiation (W m -2 ), air temperature (℃), wind speed (m s -1 ), relative humidity (%), and precipitation (m day -1 ) as well as daily rates of water inflow (m 3 day -1 ), inflow temperature (℃), and daily rates of outflow (m 3 day -1 ) [ Hipsey et al 2019 ].…”

Minimizing environmental impact whilst securing drinking water quantity and quality demands from a reservoir

“…To simulate reservoir management and its impact on the water body, we applied the one‐dimensional “General Lake Model” (GLM) coupled by the AquaticEcoDynamics library for capturing the thermal stratification and the DO dynamics in the hypolimnion. GLM is an open‐source community model that simulates water balance, vertical stratification, mixing, heat exchange, and the effect of inflows/outflows (Bruce et al, ; Hipsey et al, ). To capture the DO dynamics in the hypolimnion, we added a simple oxygen model with two temperature‐dependent depletion rates: the water column oxygen depletion rate J V (g·m −3 ·year −1 ) and the sediment‐related (i.e., areal) oxygen depletion rate J A (g·m −2 ·year −1 ).…”

Water clarity and temperature effects on walleye safe harvest: an empirical test of the safe operating space concept

“…Water clarity was measured by Secchi depth (Appendix S1: Table S1) and converted to daily light extinction coefficients using a non-linear hierarchical model (Appendix S1). Daily water temperature profiles were estimated using an open-source hydrodynamic model (General Lake Model v2.2; Hipsey et al 2019), modified to incorporate daily estimates of light attenuation. The temperature model was calibrated to in situ temperature data using a Nelder-Mead gradient descent algorithm, whereby the overall root-mean-squared error (RMSE) was minimized by altering model parameters (Appendix S1: Table S2; final RMSE of 1.26°C).…”