Soft high-energy hadron collisions are driven by nonperturbative physics. This thesis investigates nonperturbative colour reconnections in a Monte Carlo event generator. This model allows for an improved simulation of soft inclusive events and the underlying event. To account for diffraction in simulated inclusive event samples, a unitarization model for diffractive cross sections, based on a two-channel eikonal formalism and enhanced pomeron diagrams, is analytically developed and studied
