Simulating environmental flows and wind energy systems presents a significant computational challenge due to the complex nature of these phenomena and high computational costs associated with traditional modeling techniques. In this work, we propose an advanced framework for the efficient simulations of environmental flows using projection-based reduced order models (ROMs) within the variational multiscale (VMS) turbulence modeling approach [1]. We use the POD-Galerkin method for the ROMs to capture the dominant flow features and drastically reduce the computational time while maintaining a high accuracy. We extend this framework through a two-level ROM strategy, where the wind turbines are represented using the actuator line model (ALM), reducing model complexity and preserving the accuracy of turbine wake interactions. Additionally, mesh-based hyper reduction techniques are implemented, resulting in further computational cost savings at the reduced basis level. We also incorporate non-linear POD methods alongside Artificial Neural Network (ANN)-based closure models, which address unresolved dynamics and further improve simulation accuracy. The proposed approach is validated using standard benchmark cases as a first step. Later, we demonstrate its versatility by applying the ROM framework to stratified flows and wind turbine simulations, including various configurations like single turbines and multiple turbines placed at varying distances. These simulations show the method’s potential to model high-turbulence scenarios and complex environmental conditions efficiently. Our ROM-based approach offers accurate and computationally affordable solutions for wind energy and environmental flow applications that will be a core basis to simulate wind farms at reduced computational costs, thereby accelerating the design optimization process in wind farm modeling. [1] Y. Bazilevs, V.M. Calo, J.A. Cottrell, T.J.R. Hughes, A. Reali, G. Scovazzi, Variational multiscale residual-based turbulence modeling for large eddy simulation of incompressible flows. Computer methods in applied mechanics and engineering, 197(1-4), 173-201, 2007.