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The benching of hillslopes in Tunisian semi-arid regions is intended to reduce soil erosion, store water runoff and enhance infiltration on hillslopes. The hydrological impact of bench terrraces remains unknown; therefore, that of a cascade of bench terraces built in June 1997 on a 14.48 ha hillslope in the Ousseltia region of central Tunisia was evaluated. Accurate topographic measurements were used to determine precise characteristics and hydrological effects for each contour ridge. In June 3 2006, the total retention capacity of the cascade was 2535 in. In nine years, the channels uphill of the bench terraces have lost 31% of their initial storage capacity. Each year, approximately 171 1 of sediments are retained uphill of these bench terraces. Before the bench terraces were set up, the runoff coefficient for a rainfall event of 64 turn was 65%. In the first year after introducing the terraces, the runoff coefficient for a similar event was 20%. After nine years, the runoff coefficient is 38%. Moreover, if all the runoff area uphill of the benches were ploughed, the runoff would be reduced to zero for a 64 mm rainfall event, even after nine years. Thus, bench terraces do significantly reduce runoff, erosion and sediment transport on this engineered hillslope.