How Does Flow Alteration Propagate Across a Large, Highly Regulated Basin? Dam Attributes, Network Context, and Implications for Biodiversity

Journal Article · Fri Jun 17 00:00:00 EDT 2022 · Earth's Future

DOI:https://doi.org/10.1029/2021EF002490· OSTI ID:1872817

Ruhi, Albert  ^[1]; Hwang, Jeongwoo  ^[2]; Devineni, Naresh  ^[3]; Mukhopadhyay, Sudarshana  ^[4]; Kumar, Hemant  ^[5]; Comte, Lise  ^[6]; Worland, Scott  ^[4]; Sankarasubramanian, A.  ^[5]

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1. Department of Environmental Science, Policy, and Management University of California, Berkeley Berkeley CA USA
2. Department of Earth and Environmental Engineering Columbia University New York NY USA, Department of Civil Engineering The City University of New York (City College) New York NY USA
3. Department of Civil Engineering The City University of New York (City College) New York NY USA
4. Department of Biological and Environmental Engineering Cornell University Ithaca NY USA
5. Department of Civil, Construction, and Environmental Engineering North Carolina State University Raleigh NC USA
6. School of Biological Sciences Illinois State University Normal IL USA

Abstract Large dams are a leading cause of river ecosystem degradation. Although dams have cumulative effects as water flows downstream in a river network, most flow alteration research has focused on local impacts of single dams. Here we examined the highly regulated Colorado River Basin (CRB) to understand how flow alteration propagates in river networks, as influenced by the location and characteristics of dams as well as the structure of the river network—including the presence of tributaries. We used a spatial Markov network model informed by 117 upstream‐downstream pairs of monthly flow series (2003–2017) to estimate flow alteration from 84 intermediate‐to‐large dams representing >83% of the total storage in the CRB. Using Least Absolute Shrinkage and Selection Operator regression, we then investigated how flow alteration was influenced by local dam properties (e.g., purpose, storage capacity) and network‐level attributes (e.g., position, upstream cumulative storage). Flow alteration was highly variable across the network, but tended to accumulate downstream and remained high in the main stem. Dam impacts were explained by network‐level attributes (63%) more than by local dam properties (37%), underscoring the need to consider network context when assessing dam impacts. High‐impact dams were often located in sub‐watersheds with high levels of native fish biodiversity, fish imperilment, or species requiring seasonal flows that are no longer present. These three biodiversity dimensions, as well as the amount of dam‐free downstream habitat, indicate potential to restore river ecosystems via controlled flow releases. Our methods are transferrable and could guide screening for dam reoperation in other highly regulated basins.

• Research Organization: City Univ. of New York (CUNY), NY (United States); Univ. of California, Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); National Science Foundation (NSF); U S Department of Agriculture (USDA); University of California Berkeley
• Grant/Contract Number: DE‐SC0018124; SC0018124; CBET 1442909; CBET 1805293; NIFA NC-1189
• OSTI ID: 1872817
• Alternate ID(s): OSTI ID: 1876244; OSTI ID: 1978508
• Journal Information: Earth's Future, Journal Name: Earth's Future Vol. 10 Journal Issue: 6; ISSN 2328-4277
• Publisher: American Geophysical Union (AGU)
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES