Use of UAV Data and HEC-RAS Model for Dimensioning of Hydraulic Structures on Forest Roads

In terms of engineering standards, the dimensions hydraulic structures such as culverts on forest roads should have capability to drain expected maximum discharge for a 50-year return period during their lifespan (i.e., 20 years). Turkey, Talbot’s formula, empirical method, has commonly been used in determining required cross-sectional area (CSA) structures. However, practice, road engineers Turkey do not pay enough attention construction with calculated by formula. present study, Hydrological Engineering Centre – River Analysis System (HEC-RAS) model was evaluate installed ability discharges, aim those that could meet this requirement. To purpose, 6+000 km No. 410 Acısu Forest Enterprise, Gerede Directorate (Bolu, Turkey) selected study area. total, 15 small watersheds crossed were delineated, only six them having cross-drainage The HEC-RAS geometry generated manual unmanned aerial vehicle (UAV) flights at altitudes 5–15 m, providing very high spatial resolution (<1 cm). discharges estimated using Rational, Kürsteiner, and Soil Conservation Service-Curve Number (SCS-CN) methods. Maximum 0.18–6.03 found Rational 0.45–4.46 Kürsteiner 0.25–7.97 SCS-CN method. According CSA simulations, most culvert CSAs formula be incapable draining discharges. concluded can provide accurate reliable results roads.