Environmental flow scenarios for a regulated river system: projecting catchment‐wide ecosystem benefits and consequences for hydroelectric production

Abstract. The simulation of routing and distribution of water through a regulated river system with a river management model will quickly result in complex and nonlinear model behaviour. A robust sensitivity analysis increases the transparency of the model and provides both the modeller and the system manager with a better understanding and insight on how the model simulates reality and management operations. In this study, a robust, density-based sensitivity analysis, developed by Plischke et al. (2013), is applied to an eWater Source river management model. This sensitivity analysis methodology is extended to not only account for main effects but also for interaction effects. The combination of sensitivity indices and scatter plots enables the identification of major linear effects as well as subtle minor and nonlinear effects. The case study is an idealized river management model representing typical conditions of the southern Murray–Darling Basin in Australia for which the sensitivity of a variety of model outcomes to variations in the driving forces, inflow to the system, rainfall and potential evapotranspiration, is examined. The model outcomes are most sensitive to the inflow to the system, but the sensitivity analysis identified minor effects of potential evapotranspiration and nonlinear interaction effects between inflow and potential evapotranspiration.

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Variation in turbidity with precipitation and flow in a regulated river system – River Göta Älv, SW Sweden

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-255-2013 ◽

2013 ◽

Vol 10 (1) ◽

pp. 255-293

Author(s):

G. Göransson ◽

M. Larson ◽

D. Bendz

Keyword(s):

Sediment Transport ◽

Suspended Sediment ◽

Fresh Water ◽

Surface Runoff ◽

River System ◽

Regulated River ◽

Suspended Sediment Transport ◽

Simple Relationship ◽

Main River ◽

Lake Vänern

Abstract. The turbidity variation in time and space is investigated in the downstream stretch of the river Göta Älv in Sweden. The river is heavily regulated and carries the discharge from the largest fresh water lake in Sweden, lake Vänern, to the outflow point in Göteborg Harbour on the Swedish west coast. The river is an important waterway and serves as fresh-water supply for 700 000 users. Turbidity is utilised as an indicator to ensure sufficient quality of the intake water to the treatment plant. The overall objective of the study was to investigate the influence of rainfall, surface runoff, and river water flow on the temporal and spatial variability of the turbidity in the regulated river system by employing statistical analysis of an extensive data set. Six-year long time series of daily mean values on precipitation, discharge, and turbidity from six stations along the river were examined primarily through linear correlation and regression analysis, combined with nonparametric tests and analysis of variance. The analyses were performed on annual, monthly, and daily basis, establishing temporal patterns and dependences, including seasonal changes, impacts from extreme events, influences from tributaries, and the spatial variation along the river. The results showed that there is no simple relationship between discharge, precipitation, and turbidity, mainly due to the complexity of the runoff process, the regulation of the river, and the effects of lake Vänern and its large catchment area. For the river Göta Älv, significant, positive correlations between turbidity, discharge, and precipitation could only be found during periods with high flow combined with heavy rainfall. Local precipitation does not seem to have any significant impact on the discharge in the main river, which is primarily governed by the precipitation at catchment scale. The discharge from the lake Vänern determines the base level for the turbidity in the river, whereas local surface runoff and tributary discharge induced by rainfall govern the temporal variability in turbidity. Autocorrelation analysis indicates a temporal persistence in turbidity of about 10 days. The results also show that erosion in the main river, from the river bed and banks, is not a dominant contributor to the suspended sediment transport in the river. Further studies on the correlation between turbidity and suspended sediment transport and in relation to erosion processes are suggested.

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Environmental Flow Assessment of a Tropical River System Using Hydrological Index Methods

Water ◽

10.3390/w13182477 ◽

2021 ◽

Vol 13 (18) ◽

pp. 2477

Author(s):

Mohammad Haroon Hairan ◽

Nor Rohaizah Jamil ◽

Mohammad Noor Amal Azmai ◽

Ley Juen Looi ◽

Moriken Camara

Keyword(s):

River Flow ◽

Maximum Flow ◽

River System ◽

Environmental Flow ◽

Low Flow ◽

Index Method ◽

Flood Pulses ◽

Post Impact ◽

High Flood ◽

High Level

Tropical rivers and wetlands are recognized as one of the greatest and most abundant ecosystems in terms of ecological and social benefits. However, climate change, damming, overfishing, water pollution, and the introduction of exotic species threaten these ecosystems, which puts about 65% of river flow and aquatic ecosystems under a moderate to high level of threat. This paper aims to assess the environmental flow of the Selangor River based on the hydrological index method using the Global Environmental Flow Calculator (GEFC) and Indicators of Hydrological Alterations (IHA) software. The daily flow data collected by the Department of Irrigation and Drainage (DID), Malaysia, over a 60-year period (1960–2020) was used in this study to assess the Selangor River flow alterations. As per the results, the river flow has had two distinct periods over the last 60 years. In the first period, the river flows without any alteration and has a natural flow with high flood pulses and low flow pulses. While in the second, or post-impact, period, the flow of the river has a steady condition throughout the year with very little fluctuations between the dry and wet seasons of the year. From the overall comparison of the pre- and post-impact periods, it can be concluded that the minimum flow in the dry seasons of the year has increased, while the maximum flow has decreased in the monsoon seasons during the post-impact period. As a result, the Flow Duration Curve (FDC) and Environmental Management Class (EMC) analysis of the river flow recommends that the Selangor River be managed under EMC “C” to provide sufficient water for both human use and ecosystem conservation, which would also help to avoid a water level drop in the reservoirs. However, further holistic studies are suggested for a detailed analysis of the effects of the dams on aquatic biodiversity and ecosystem services in the Selangor River Basin.

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Remedial strategy of algal proliferation in a regulated river system by integrated hydrological control: an evolutionary modelling framework

Marine and Freshwater Research ◽

10.1071/mf13004 ◽

2014 ◽

Vol 65 (5) ◽

pp. 379 ◽

Cited By ~ 5

Author(s):

Dong-Gyun Hong ◽

Kwang-Seuk Jeong ◽

Dong-Kyun Kim ◽

Gea-Jae Joo

Keyword(s):

Chlorophyll A ◽

Phytoplankton Biomass ◽

River Flow ◽

Winter Season ◽

River System ◽

Regulated River ◽

Water Volume ◽

Ample Evidence ◽

Chlorophyll A Concentration ◽

Rule Set

We simulated water-quality measures in a regulated river system (the lower Nakdong River) under simultaneous discharge control at upriver dams and an estuarine barrage with the goal of reducing phytoplankton biomass (chlorophyll a concentration). We used genetic programming (GP) to create a rule-set-based predictive model for the chlorophyll a concentration based on 16 years (1994–2009) of meteorological, hydrological, and limnological data. The rule-set model used eight variables, including water temperature, dam and estuarine barrage discharge, phosphate and silica concentrations, and accurately predicted the phytoplankton biomass (determination coefficients, r2, for training and test data were 0.52 and 0.45, respectively). According to sensitivity and scenario analyses, a larger water volume resulting from increased discharge from upriver dams and decreased discharge from an estuarine barrage would reduce chlorophyll a concentrations at the study site. This result provided ample evidence that simultaneous manipulation of dam and estuarine discharge rates could effectively increase river flow and flush aggregated algal populations downstream. Additionally, we considered that even small increases in river flow could play a role in diluting phytoplankton biomass during the dry winter season when estuarine discharge remains low. These two hydrological mechanisms could be used as selective strategies for water-resource management.

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Migration patterns and estuarine aggregations of a catadromous fish, Australian bass (Percalates novemaculeata) in a regulated river system

Marine and Freshwater Research ◽

10.1071/mf16125 ◽

2017 ◽

Vol 68 (8) ◽

pp. 1544 ◽

Cited By ~ 13

Author(s):

D. J. Harding ◽

R. G. Dwyer ◽

T. M. Mullins ◽

M. J. Kennard ◽

R. D. Pillans ◽

...

Keyword(s):

Fish Species ◽

Large Scale ◽

River System ◽

Regulated River ◽

Regulated Rivers ◽

Migration Patterns ◽

Migratory Response ◽

Resource Managers ◽

Receiver Array ◽

Downstream Movement

Catadromous fish species require adequate flows to migrate between fresh and saltwater habitats to reproduce. However, artificial barriers and flow alteration affect fish populations by reducing habitat connectivity and disrupting movement cues. In regulated rivers, it is critical that migratory flow requirements are quantified to optimise water allocation for multiple users. In the present study, we assessed the migratory timing, flow and estuarine aggregation requirements for Australian bass (Percalates novemaculeata). Over 2 years, 66 bass were tracked using an acoustic receiver array in the Logan River (Qld, Australia). Bass performed large-scale downstream movements in response to elevated winter flows (40 and 108m3 s–1), which facilitated migration to the lower estuary, where salinity conditions were appropriate for spawning. Bass migrations occurred only when gonads were mature, despite large flows providing opportunities for movement outside this period. Experimental flow releases from an impoundment (2.1m3 s–1) during winter did not elicit a migratory response. Connectivity between upstream and estuarine habitats was reduced by the presence of instream weirs, with downstream movement across weirs occurring only when sufficient flow magnitude was achieved (>76.1m3 s–1). These findings are relevant for water resource managers formulating environmental flow rules for catadromous fish species in systems with multiple instream artificial barriers.

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Prioritising the rehabilitation of fish passage in a regulated river system based on fish movement

Ecological Management & Restoration ◽

10.1111/emr.12140 ◽

2015 ◽

Vol 16 (1) ◽

pp. 67-72 ◽

Cited By ~ 2

Author(s):

Justin O'Connor ◽

Frank Amtstaetter ◽

Matthew Jones ◽

John Mahoney

Keyword(s):

River System ◽

Fish Passage ◽

Regulated River ◽

Fish Movement

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Let it flow: modeling ecological benefits and hydropower production impacts of banning zero-flow events in a large regulated river system

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.147010 ◽

2021 ◽

pp. 147010

Author(s):

Åsa Widén ◽

Birgitta Malm Renöfält ◽

Erik Degerman ◽

Dag Wisaeus ◽

Roland Jansson

Keyword(s):

River System ◽

Regulated River ◽

Flow Modeling ◽

Ecological Benefits ◽

Hydropower Production ◽

Zero Flow

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Assessment and ranking flood events in a regulated river using information and complexity measures

Journal of Physics Conference Series ◽

10.1088/1742-6596/2090/1/012169 ◽

2021 ◽

Vol 2090 (1) ◽

pp. 012169

Author(s):

Mohamad Basel Al Sawaf ◽

Kiyosi Kawanisi ◽

Cong Xiao

Keyword(s):

Risk Control ◽

River System ◽

River Regulation ◽

Environmental Risks ◽

Regulated River ◽

Flood Events ◽

Regulated Rivers ◽

Complexity Measures ◽

Complexity Metrics

Abstract The availability of a robust approach that describe the hidden features of flood events in regulated rivers is of great importance. The key goal of this research is to utilize some of information and complexity measures to assess and rank flood patterns within a regulated river system. To meet this goal, the Metric Entropy (ME) as measure of information content and Rényi Complexity (CR) as a quantification for complexity content were employed. To examine the role of river regulation on flood risk control, river stage records of two monitoring stations located at downstream of two different dams were considered in this research. The findings show that information and complexity metrics offer an image of the randomness embedded in dataset and the presence of internal patterns in studied data records. In general, this research shows that natural environmental risks and disasters can be assessed and ranked using a promising physical scheme based on information and complexity measures.

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