A gas monitoring system for monitoring gas leaks from a gas turbine engine disposed within a gas turbine enclosure includes a controller including a processor and a memory communicatively coupled to the processor. The memory stores instructions which when executed by the processor perform operations including obtaining one or more operational parameters associated with a gas turbine system having the gas turbine engine from one or more sensors during operation of the gas turbine engine. The operations also include utilizing a gas leakage monitoring model to monitor for gas leaks within the gas turbine enclosure and to generate a gas index indicative of a severity of a gas leak within the gas turbine enclosure based on the one or more operational parameters. The operations further include outputting the index.