The greatest run off and soil loss rates are recorded for intense but infrequent storm events. Several papers discuss the magnitude of erosion. Wainwright notes that 100 mm h−1 of precipitation fell in the extreme rainfall event of 22 September 1992 in south-eastern France , causing soil loss of 34 Mg ha−1. Martínez-Casasnovas et al. suggest that soil loss of 282 Mg ha−1occurred during a storm with a maximum intensity of 187 mm h−1 which was recorded for north-east Spain . Besides these exceptional long return period events, others that have lower intensity but which are much more usual can cause large rates of erosion, and in some circumstances, rills and ephemeral gullies may be observed.