Improving drainage conditions of forest roads using the GIS and forest road simulator

Abstract

In this study a new method of locating culverts is presented with the composition of achieved discharge from hydrological analysis and simulated forest roads in RoadEng 3D simulator to improve drainage condition. Locating culverts was performed on a small scale (1:20 000, using GIS) and large scale (1:2 000, road geometric design simulator). The small-scale study regarding the achieved discharge from streams shows that the installation of some culverts is not necessary. The large-scale study also showed that the geometric design of forest road has a significant effect on locating culverts and its accuracy. To improve drainage conditions 6 culverts and 2 waterfronts taking into account the geometric design of forest road, hydrological conditions and appropriate intervals (155 m) have been proposed. No installation or lack of accuracy to find the best location of culverts may result in the occurrence of creep and landslide, so the cost of destruction would be several times higher than the cost of technical buildings construction.

Stream-crossing Approaches on Forest Roads Networks: A Critical Review on Practices in Türkiye

“…The most preferred design methods, such as the rational method and other empirical assumptions, use precipitation data as the relevant flow data are usually limited (Tolland et al,1998). Many factors including vegetation, soil type in the area, topography and microtopography of the hillside across the road, the hydrology of the area including rainfall discharges of streams, time of runoff concentration, length, and gradient of streams are important in estimating runoff (Nasiri and Askari, 2020).…”

“…Many researches have been conducted for more efficient planning of forest road-stream-crossing structures such as: using RoadEng software to optimize forest road routes, using Distributed Hydrology Soil Vegetation Model (DHSVM) to determine impact, analysis of forest road network in watershed hydrology, calculating the sediment distribution and finding the best culvert installation method (Nasiri and Askari, 2020).…”

“…The stream-crossing structure construction in small forests watershed can be performed in four steps: (i) planning and selecting the location of structure installation, (ii) conveying surface runoff by a culvert in its natural route (iii) preparation of foundations, and (iv) installing the structure. ForCulverts as an extension package of ArcView software that use the rational method used to estimate for peak discharges, has been developed to locate culverts regarding the road gradient and hydrology (Nasiri and Askari, 2020). Nasiri and Askari (2020) presented a methodology to offer the best location for the culverts to improve the drainage systems of forest roads by evaluating the area at the point of hydrological flow and assessing (on a small and large scale) the location of existent culverts (Figure 2).…”

“…ForCulverts as an extension package of ArcView software that use the rational method used to estimate for peak discharges, has been developed to locate culverts regarding the road gradient and hydrology (Nasiri and Askari, 2020). Nasiri and Askari (2020) presented a methodology to offer the best location for the culverts to improve the drainage systems of forest roads by evaluating the area at the point of hydrological flow and assessing (on a small and large scale) the location of existent culverts (Figure 2). In a study conducted by Harris et al (2008), it was stated that the culverts built for wood production in forested water basins northwestern California in the last decades were inadequate as a result of the accumulation of wood and log pieces and sediment occurring at peak flows.…”

“…Figure 2. Culvert locating process (Nasiri and Askari, 2020) NetHydro is a Netcad software module that defines water catchment areas and drainage networks of these areas. It can perform precipitation analysis according to all distribution types, calculate peak flow rates according to unit hydrographs and flood risk areas in flow branches by calculating flood flow rates according to different years (NetHydro, 2021).…”