Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs

Abstract. Numerical models are an important tool for simulating temperature, hydrodynamics, and water quality in lakes reservoirs. Existing differ dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity temperature) one (1D), two (2D) or three (3D) dimensions. The different approaches based on levels simplification the description hydrodynamic processes result demands computational power. aim this study is to compare with dimensionalities analyze differences between model results relation simplifications. We simulations thermal stratification, substance transport density currents a medium-sized drinking-water reservoir subtropical zone, using widely used open-source models: GLM CE-QUAL-W2 Delft3D (3D). were operated identical initial boundary conditions over 1-year period. Their performance was assessed comparing measurements turbulence. Our show that all capable seasonal changes temperature stratification. Flow velocities, only available 2D 3D approaches, more challenging reproduce, but showed closer agreement observations. With increasing dimensionality, also increased terms error, correlation variance. None provided good observations mixed layer depth, which affects spreading inflowing as build outputs models.