Original scientific paper
https://doi.org/10.5552/crojfe.2023.1701
Use of UAV Data and HEC-RAS Model for Dimensioning of Hydraulic Structures on Forest Roads
Ahmet Açıl
; Karabük University Faculty of Forestry 78050 Karabük TÜRKIYE
Abdurrahim Aydın
; Düzce University Faculty of Forestry 81620 Düzce TÜRKIYE
Remzi Eker
; İzmir Katip Çelebi University Faculty of Forestry 35620 İzmir TÜRKIYE
Ahmet Duyar
; Karabük University Faculty of Forestry 78050 Karabük TÜRKIYE
Abstract
forest roads should have the capability to drain the expected maximum discharge for a 50-year
return period during their lifespan (i.e., 20 years). In Türkiye, Talbot’s formula, as empirical
method, has commonly been used in determining the required cross-sectional area (CSA) of
the structures. However, in practice, forest road engineers in Türkiye do not pay enough attention
to their construction with required dimensions calculated by Talbot’s formula. In the
present study, the Hydrological Engineering Centre – River Analysis System (HEC-RAS)
model was used to evaluate the dimensions of installed structures in terms of their ability to
drain maximum discharges, with the aim of determining the required dimensions for those
that could not meet this requirement. To this purpose, the 6+000 km forest road No. 410 in
Acısu Forest Enterprise, Gerede Forest Directorate (Bolu, Türkiye) was selected as the study
area. In total, 15 small watersheds crossed by the forest road were delineated, with only six of
them having cross-drainage structures. The HEC-RAS model geometry was generated by
manual unmanned aerial vehicle (UAV) flights at altitudes of 5–15 m, providing very high
spatial resolution (<1 cm). The maximum discharges of the watersheds were estimated for the
HEC-RAS model using the Rational, Kürsteiner, and Soil Conservation Service-Curve
Number
(SCS-CN) methods. Maximum discharges of 0.18–6.03 were found for the Rational
method, 0.45–4.46 for the Kürsteiner method, and 0.25–7.97 for the SCS-CN method. According
to the HEC-RAS hydraulic model CSA simulations, most of the installed culvert CSAs
calculated by Talbot’s formula were found to be incapable of draining maximum discharges.
The study concluded that the HEC-RAS model can provide accurate and reliable results for
determining the dimensions of such structures for forest roads.
Keywords
forest roads, HEC-RAS, Hydraulic structures, SCS-CN, UAV
Hrčak ID:
290889
URI
Publication date:
13.1.2023.
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