Modeling Flow-Ecology Responses in the Anthropocene: Challenges for Sustainable Riverine Management

Horne, Avril; Nathan, Rory; Poff, N. LeRoy; Bond, Nick; Webb, J. Angus; Wang, Jun; John, Andrew

doi:10.1093/biosci/biz087

Cited by 67 publications

(58 citation statements)

References 78 publications

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“…An overarching concern for predicting the fate of aquatic ecosystems is that while hydrologic variability has been identified as a control on ecological processes, many of the current empirical relationships that are used to govern management decisions are rooted in climatic stationarity (Horne et al, 2019). These assumptions fail to incorporate a shifting baseline climate regime, with already variable regions predicted to become even more volatile.…”

Section: Discussionmentioning

confidence: 99%

Variability of stream extents controlled by flow regime and network hydraulic scaling

Lapides

Leclerc

Moidu

et al. 2021

Hydrological Processes

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Stream networks expand and contract through time, impacting chemical export, aquatic habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual framework to explore how flow regime and stream network hydraulic scaling factors co-determine the relative temporal variability in L (denoted here as the total wetted channel drainage density). Network hydraulic scaling determines how much L changes for a change in Q, while the flow regime describes how Q changes in time. We compiled datasets of colocated dynamic stream extent mapping and discharge to analyze all globally available empirical data using the presented framework. We found that although variability in L is universally damped relative to variability in Q (i.e., streamflow is relatively more variable in time than network extent), the relationship is elastic, meaning that for a given increase in the variability in Q, headwater catchments will experience greaterthan-proportional increases in the variability of L. Thus, under anticipated climatic shifts towards more volatile precipitation, relative variability in headwater stream network extents can be expected to increase even more than the relative variability of discharge itself. Comparison between network extents inferred from the L-Q relationship and blue lines on USGS topographic maps shows widespread underestimation of the wetted channel network by the blue line network.

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Section: Discussionmentioning

confidence: 99%

Variability of stream extents controlled by flow regime and network hydraulic scaling

Lapides

Leclerc

Moidu

et al. 2021

Hydrological Processes

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“…Previously, e-flow studies and applications relied heavily on regime-averaged metrics (mean seasonal flow characteristics) to explain changes in ecosystem state variables (abundance of species). However, scientists have suggested greater adoption of ecological responses related to process-based (processes contributing to population size) and species traits (e.g., habitat selection traits to improve species fitness) that are rooted in a strong ecological foundation [11][12][13][14] . A recent study described these approaches broadly and stressed the importance of performing repeated measurements of ecological responses over time, focusing on reactions that can be linked directly or indirectly to demographic processes 12 .…”

mentioning

confidence: 99%

Ecological responses to flow variation inform river dolphin conservation

Paudel

Koprowski

Thakuri

et al. 2020

Sci Rep

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Many environmental flow (e-flow) studies and applications have predominantly used state—(i.e., at a single time point) and rate—(i.e., temporal change) based demographic characteristics of species representing lower trophic levels (e.g., fish communities) to build flow-ecology relationships, rather than using a process that incorporates population dynamics. Recent studies have revealed the importance of incorporating data on species traits when building flow-ecology relationships. The effects of flow on keystone megafauna species (i.e., body mass ≥ 30 kg) reverberate through entire food webs; however, the relationships between flow and these species are not well understood, limiting the scope of the relationships used in flow management. Here, we fill this gap by incorporating the habitat selection traits at different flows of a freshwater apex predator, Ganges River dolphin (GRD, Platanista gangetica gangetica), which plays a significant role in maintaining the structure, functions and integrity of the aquatic ecosystem. Using temporally and spatially measured GRD habitat selection traits, we quantified flow-ecology responses in the Karnali River of Nepal during the low-flow season when habitat was heavily reduced and water demand was highest. We define ecological responses as suitable habitat templates with enough usable surface area to support GRD fitness by improving reproduction and survival. We measured the available and occupied habitats to develop flow-ecology responses. Variation in flow resulted in substantial differences in the ecological response across time and space, suggesting that aquatic species adjusted in a variety of habitats to support their life histories and maintain viable populations. The limited availability of suitable habitats combined with uninformed water regulations by humans likely places GRDs under severe physiological stress during low-water seasons (i.e., January–April), suggesting that reduced flows contribute to the process of endangering and extirpating highly sensitive endemic aquatic biodiversity. Our study reveals that ad hoc or experience-based flow management is no longer tenable to maintain the integrity and functionality of aquatic ecosystems. We stress that quantifying the flow-ecology relationships of foundational species, particularly megafauna, in response to flow variation is crucial for monitoring the effects of water alterations and determining the minimum flows needed for maintaining healthy and functional freshwater ecosystems in the Anthropocene.

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“…Where water quantities are limited not all flow elements can be provided for all environmental needs (Horne et al ., 2010). Implementing sustainable river flows requires understanding the responses of riverine ecosystems to stresses (Horne et al ., 2019). In recent years, there has been considerable effort dedicated to improve methods for estimating environmental flow requirements; however, few studies have considered how to operate water programmes to supply flow requirements effectively (Harman and Stewardson, 2005).…”

Section: The Environmental Flow Requirementmentioning

confidence: 99%

Fulfillment of river environmental flow: applying Nash theory for quantitative‐qualitative conflict resolution in reservoir operation

Farhadian

Bozorg‐Haddad

Loáiciga

2020

Water & Environment J

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The construction of reservoirs for water supply alters the riverine ecology and changes water quality. It is, therefore, imperative to estimate and provide the riverine environmental flow requirement to prevent irreversible environmental damage and to maintain suitable water quality. Water releases from reservoirs constitute the means for meeting environmental flow and water quality requirements downstream from reservoirs. These requirements can be realized through the modification of the reservoir operation programmes by reallocating a percentage of the reservoir releases otherwise dedicated to quantitative objectives. This is performed in this study by considering the qualitative (i.e. pertaining to water quality) objectives alongside quantitative objectives of reservoir releases in order to achieve a general coverage for an operating programme that balances in the most rational manner the interests of riverine environmental protection and quantitative functions. The case study area is located in the river reach between the Gotvand reservoir and Shooshtar city in the Gotvand‐Karoon reservoir‐river system in Iran. The range of riverine environmental flow is calculated in the study river reach with hydrologic methods. Water quality is simulated and included reservoir operation with the QUAL‐2K simulation model. The existing quantitative and qualitative objectives for reservoir operation are determined and classified. The best reservoir releases corresponding to three scenarios are determined by the Nash theory considering all possible objectives in the reservoir‐river system. These scenarios allocate relative weights to defined objectives and releases were determined to be equal to 183.8, 141.8 and 206.8 m3/s for three scenarios.

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Modeling Flow-Ecology Responses in the Anthropocene: Challenges for Sustainable Riverine Management

Cited by 67 publications

References 78 publications

Variability of stream extents controlled by flow regime and network hydraulic scaling

Variability of stream extents controlled by flow regime and network hydraulic scaling

Ecological responses to flow variation inform river dolphin conservation

Fulfillment of river environmental flow: applying Nash theory for quantitative‐qualitative conflict resolution in reservoir operation

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