A method for operating a wind turbine, the method comprising: calculating, via a processor, one or more blade root loads comprising a blade root resultant moment of at least one rotor blade of the wind turbine; estimating, via the processor, a span-wise loading of the rotor blade based at least partially on the one or more blade root loads; determining, via the processor, a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more estimated deformations occurring on the rotor blade; and controlling, via a processor, the wind turbine based on the deformation margin, and wherein calculating the blade root load of at least one rotor blade of the wind turbine further comprises: measuring, via one or more sensors, a plurality of operating parameters of the wind turbine; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment. calculating, via a processor, one or more blade root loads comprising a blade root resultant moment of at least one rotor blade of the wind turbine; estimating, via the processor, a span-wise loading of the rotor blade based at least partially on the one or more blade root loads; determining, via the processor, a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more estimated deformations occurring on the rotor blade; and controlling, via a processor, the wind turbine based on the deformation margin, and wherein calculating the blade root load of at least one rotor blade of the wind turbine further comprises: measuring, via one or more sensors, a plurality of operating parameters of the wind turbine; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment. measuring, via one or more sensors, a plurality of operating parameters of the wind turbine; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment.