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R2Cross: A Web‐Based Decision Support Tool for Instream Flows

July 2021
JAWRA Journal of the American Water Resources Association 57(4)

DOI:10.1111/1752-1688.12939

Authors:

Panagiotis D. Oikonomou

University of Vermont

Ryan R Morrison

Colorado State University

The determination of instream flows for preserving or improving aquatic ecosystems’ health often includes challenges caused by varied hydraulic conditions, ecological criteria, and socioeconomic considerations. Despite the abundance of available methodologies, there are few available desktop or online applications enabling rapid assessment of instream flows that incorporate pertinent geospatial information for the region. We present R2Cross, a user‐friendly, online, instream flow rate calculation tool that was developed for aiding water allocation decisions in the state of Colorado. The R2Cross tool is the only existing online decision support tool based on a hydraulic rating method. It estimates hydraulic conditions at different water stages in a stream reach and compares them to habitat criteria to determine biological instream flow recommendations. Cloud‐based Geographic Information System features and additional tools are incorporated that augment information and aid in evaluating ecological needs. The development of the R2Cross tool enables an open‐access interface for management authorities and stakeholders to evaluate ecological needs at stream reaches. It automates the reporting process and could assist in making water management decisions about environmental protection. Although the R2Cross tool was developed for the state of Colorado, it is generalizable to other stream systems assuming similar habitat criteria.

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R2Cross: A Web-Based Decision Support Tool for Instream Flows

Panagiotis D. Oikonomou , Rumpal Sidhu, Tyler Wible, and Ryan R. Morrison

Research Impact Statement: R2Cross is an intuitive and robust web-accessible tool for assessing instream

ﬂow criteria. It ﬁlls a gap in publicly available online tools as it is uniquely based on a hydraulic rating method.

ABSTRACT: The determination of instream ﬂows for preserving or improving aquatic ecosystems’ health often

includes challenges caused by varied hydraulic conditions, ecological criteria, and socioeconomic considerations.

Despite the abundance of available methodologies, there are few available desktop or online applications

enabling rapid assessment of instream ﬂows that incorporate pertinent geospatial information for the region.

We present R2Cross, a user-friendly, online, instream ﬂow rate calculation tool that was developed for aiding

water allocation decisions in the state of Colorado. The R2Cross tool is the only existing online decision support

tool based on a hydraulic rating method. It estimates hydraulic conditions at different water stages in a stream

reach and compares them to habitat criteria to determine biological instream ﬂow recommendations. Cloud-

based Geographic Information System features and additional tools are incorporated that augment information

and aid in evaluating ecological needs. The development of the R2Cross tool enables an open-access interface for

management authorities and stakeholders to evaluate ecological needs at stream reaches. It automates the

reporting process and could assist in making water management decisions about environmental protection.

Although the R2Cross tool was developed for the state of Colorado, it is generalizable to other stream systems

assuming similar habitat criteria.

(KEYWORDS: instream ﬂows; R2Cross; web-based decision support system; Colorado; hydraulic rating

methodology.)

INTRODUCTION

Most river basins have undergone signiﬁcant

human modiﬁcations, including instream ﬂow

regime changes, threatening aquatic habitat or lead-

ing to degradation in moderate to high degrees

(Dudgeon et al. 2006; V€

or€

osmarty et al. 2010). Pro-

jected global population growth will increase water

demands in all sectors, especially the competition

for water between socioeconomic and environmental

demands (WWAP/UN-Water 2018). Management

methods, tools, and data, which are widely available

and easily accessible by water resources managers

and stakeholders, are needed to provide a system-

atic evaluation of viable allocation alternatives for

environmental needs (Oikonomou 2017). Speciﬁcally,

the natural ﬂow regime plays a crucial role for

maintaining a healthy aquatic habitat (Poff et al.

1997). However, in modiﬁed streams, due to water

diversion and/or storage infrastructure, the natural

spatiotemporal ﬂow variability is lost. Thus, deter-

mination of the minimum environmental ﬂow levels

to protect the aquatic habitat can be difﬁcult when

considering hydraulic conditions, ecological criteria,

and socioeconomic concerns.

Paper No. JAWR-20-0108-N of the Journal of the American Water Resources Association (JAWR). Received August 14, 2020; accepted

Colorado Water Institute (Oikonomou), Colorado State University Fort Collins, Colorado, USA; and Department of Civil and Environmen-

tal Engineering (Sidhu, Wible, Morrison), Colorado State University Fort Collins, Colorado, USA (Correspondence to Oikonomou: panagio-

tis.oikonomou@colostate.edu).

Citation: Oikonomou, P.D., R. Sidhu, T. Wible, and R.R. Morrison. 2021. “R2Cross: A Web-Based Decision Support Tool for Instream

Flows.” Journal of the American Water Resources Association 1–9. https://doi.org/10.1111/1752-1688.12939.

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