Road network designing in a forested watershed using network connectivity indices

Abstract

Designing and constructing a road network is one of the most critical steps of the development process in managing natural resources. The current research is going to investigate the application of network connectivity indices to the analysis of road networks in the forested watershed. First, the road network suitability map (RNSM) was created to emphasize the technical and physiographic criteria and integrated management scenarios using a weighted linear combination (WLC) and analytic network process (ANP). Subsequently, three road network alternatives (RNA) were assigned based on the priorities in the RNSM. In order to try to determine the appropriate alternative, the network connectivity of the designed alternatives looked into the forest and non-forest land uses, as well as the whole study area, using the values of alpha (α), beta (β), gamma (γ), eta (η), network density (ND) and detour indices (DI) in the context of the graph theory. Results show that the road density of the RNA2 variant (11.56 m.ha-1) is shorter than the other alternatives and the existing road network (ERN). In addition, dealing with the whole study area, we realized that the index values which are related to the number two reflect a better status than the other alternatives of alpha, beta, gamma, eta and detour index, in which they were identified to be 0.44, 1.34, 1.16, 0.45 and 0.83, respectively. RNA2 is chosen as the appropriate road network according to the network connectivity, technical and physiographical criteria, along with integrated management scenarios. Further control measures and field surveys are recommended to achieve more relevant results.

Keywords

• graph theory
• indexes
• network alternative
• road network suitability map (rnam)