@article{2ceb040a8814403fa1b1160dbe749eba,
title = "Functional Topology of Evolving Urban Drainage Networks",
abstract = "We investigated the scaling and topology of engineered urban drainage networks (UDNs) in two cities, and further examined UDN evolution over decades. UDN scaling was analyzed using two power law scaling characteristics widely employed for river networks: (1) Hack's law of length (L)-area (A) [L α Ah] and (2) exceedance probability distribution of upstream contributing area (δ) [P(A≥δ)~aδ-ε]. For the smallest UDNs (<2 km2), length-area scales linearly (h ∼ 1), but power law scaling (h ∼ 0.6) emerges as the UDNs grow. While P(A≥δ) plots for river networks are abruptly truncated, those for UDNs display exponential tempering [P(A≥δ)=aδ-ε exp (-cδ)]. The tempering parameter c decreases as the UDNs grow, implying that the distribution evolves in time to resemble those for river networks. However, the power law exponent ɛ for large UDNs tends to be greater than the range reported for river networks. Differences in generative processes and engineering design constraints contribute to observed differences in the evolution of UDNs and river networks, including subnet heterogeneity and nonrandom branching.",
keywords = "fractal, infrastructure, river network, self-organization, self-similarity, urban drainage network",
author = "Soohyun Yang and Kyungrock Paik and McGrath, {Gavan S.} and Christian Urich and Elisabeth Krueger and Praveen Kumar and Rao, {P. Suresh C.}",
note = "Funding Information: An earlier version of this manuscript was uploaded to ArXiv [arXiv:1707.04911]. This study is an outcome from the Synthesis Workshop on {\textquoteleft}{\textquoteleft}Dynamics of Structure and Functions of Complex Networks,{\textquoteright}{\textquoteright} held at Korea University in 2015. P.S.C.R. participation in the Workshop was partially supported by a U.S. Fulbright Fellowship. Financial support for this study has been jointly provided by the U.S. NSF (award 1441188; Collaborative Research—RIPS Type 2: Resilience Simulation for Water, Power and Road Networks) and National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (grant 2015R1A2A2A05001592). Partial financial support for P.S.C.R. and G.S.M. was also provided by the Lee A. Rieth Endowment and to K.P. as the Edward M. Curtis Visiting Professor, all in Lyles School of Civil Engineering, Purdue University. S.Y. was supported by a Ross Fellowship awarded by Lyles School of Civil Engineering, Purdue University. E.K. was supported by Helmholtz Centre for Environmental Research - UFZ, Germany, and a Lynn Fellowship awarded by ESE-IGP at Purdue University (Ecological Sciences and Engineering Interdisciplinary Graduate Program). C.U. was supported by Monash University 2015 Eng-IT Interdisciplinary Research Seed Funding. P.K. would like to acknowledge the support of NSF grant EAR-1331906. The Oahu sewer data were obtained from a public source supported by the City and County of Honolulu, Department of Planning and Permitting (ftp://gisftp.hicentral.com/ Layers/). Oahu natural stream watershed data were downloaded from the State of Hawaii, Office of Planning (http://planning.hawaii.gov/ gis/download-gis-data/). Sewer network data for AAC were obtained under a confidentiality agreement from the city{\textquoteright}s water utility authority. Due to confidentiality constraints, these data cannot be made publicly available, but the authors are willing to work with those needing access to these data. The authors acknowledge the local national authorities for their support, and the local water utility, who provided the infrastructure data of the AAC. The authors also acknowledge insightful comments offered by Andrea Rinaldo during the early phases of the development of concepts presented here. K.P. also acknowledges Jin A Oh and Jin Gul Joo for interesting discussions about Korean sewer networks (in 2009), which have helped K.P. to keep developing ideas on this subject. Publisher Copyright: {\textcopyright} 2017. American Geophysical Union. All Rights Reserved.",
year = "2017",
month = nov,
doi = "10.1002/2017WR021555",
language = "English",
volume = "53",
pages = "8966--8979",
journal = "Water Resources Research",
issn = "0043-1397",
publisher = "American Geophysical Union",
number = "11",
}