Abstract
Abstract. Numerical modeling provides an opportunity to quantify the reaction of lakes to alterations in their environment, such as changes in climate or hydrological conditions. The one-dimensional hydrodynamic General Lake Model (GLM) is an open-source software and widely used within the limnological research community. Nevertheless, no interface to process the input data and run the model and no tools for an automatic parameter calibration yet exist. Hence, we developed glmGUI, a graphical user interface (GUI) including a toolbox for an autocalibration, parameter sensitivity analysis, and several plot options. The tool is provided as a package for the freely available scientific code language R. The model parameters can be analyzed and calibrated for the simulation output variables water temperature and lake level. The glmGUI package is tested for two sites (lake Ammersee, Germany, and lake Baratz, Italy), distinguishing size, mixing regime, hydrology of the catchment area (i.e., the number of inflows and their runoff seasonality), and climatic conditions. A robust simulation of water temperature for both lakes (Ammersee: RMSE =1.17 ∘C; Baratz: RMSE =1.30 ∘C) is achieved by a quick automatic calibration. The quality of a water temperature simulation can be assessed immediately by means of a difference plot provided by glmGUI, which displays the distribution of the spatial (vertical) and temporal deviations. The calibration of the lake-level simulations of lake Ammersee for multiple hydrological inputs including also unknown inflows yielded a satisfactory model fit (RMSE =0.20 m). This shows that GLM can also be used to estimate the water balance of lakes correctly. The tools provided by glmGUI enable a less time-consuming and simplified parameter optimization within the calibration process. Due to this, i.e., the free availability and the implementation in a GUI, the presented R package expands the application of GLM to a broader field of lake modeling research and even beyond limnological experts.
Highlights
Because lakes respond to changes in their environment they are often considered to be “sentinels of change” (Williamson et al, 2009; Hipsey et al, 2019)
In this contribution we present the options included in glmGUI, and we show the application for two different sites, namely the pre-alpine deep lake Ammersee, southern Germany, and the shallow, Mediterranean lake Baratz, Sardinia, Italy
Plot options are provided by glmGUI for the input time series in part 2 (Fig. 1) and for all output variables generated by General Lake Model (GLM)
Summary
Because lakes respond to changes in their environment they are often considered to be “sentinels of change” (Williamson et al, 2009; Hipsey et al, 2019). In addition to the model output water temperature, the lake level is included to be calibrated in the provided automated calibration tool. In this contribution we present the options included in glmGUI, and we show the application for two different sites, namely the pre-alpine deep lake Ammersee, southern Germany, and the shallow, Mediterranean lake Baratz, Sardinia, Italy. The objectives of these two case studies are the calibration of the water temperature and lake-level simulations of GLM using the automatic calibration tool
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