Comparing the Hydrological Response of Forested Headwaters (Unregulated and Regulated with Check Dams) under Mediterranean Semi-Arid Conditions

This study has evaluated the runoff and erosion rates in torrents of Southern Italy, two forested headwaters with very similar climatic, hydrological geomorphological characteristics; one headwater, 15 check dams were installed mid-1950s, while other is not regulated engineering works. To this aim, variables have been modeled over years after dam installation using HEC-HMS (Hydrologic Engineering Center-Hydrologic Modeling System) model coupled to MUSLE (Modified Universal Soil Loss Equation) equation. The simulations shown that played a significant role reducing surface compared unregulated torrent; both catchments, well-developed forest cover determined low coefficients (lower than 0.3%) scarce generation capacity. Additionally, reduction peak flow due was significant, on average ?7.4% headwater. Check retained sediments for about 8–10 their installation, by 35%, although soil loss much lower tolerance limit catchments. After sediment retention capacity wedge depleted, yield torrent even higher (by 20%) catchment. Overall, use as catchment management strategy under semi-arid Mediterranean conditions should be considered caution, since structures could ineffective reduce water flows during floods or, some cases, may increase rates.