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

Water ◽  
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.

scholarly journals Summer Low Flow Events in the Mackenzie River System

ARCTIC ◽  
2016 ◽  
Vol 69 (3) ◽  
pp. 286 ◽  
Author(s):  
Ming-ko Woo ◽  
Robin Thorne
Keyword(s):  
River Flow ◽  
Probability Distributions ◽  
Gumbel Distribution ◽  
River System ◽  
Low Flow ◽  
Large Lakes ◽  
Storage Mechanism ◽  
Mackenzie Basin ◽  
Drainage Networks ◽  
Historical Past

Most northern rivers experience recurrent low flow conditions in the summer (June to September), and rivers of the Mackenzie Basin are no exception. Low flow affects water supply, poses problems for river traffic, and can adversely affect aquatic ecology. Factors that affect summer low flow, which encompasses flows below specified discharge thresholds of concern, include evapotranspiration that leads to water loss from flow-contributing areas, antecedent high flow in which peak discharge is followed by gradual recession to low flow, rainfall and local glacier melt events that interrupt low discharge, replenishments of flow from upstream drainage networks, and arbitrary termination of summer low flow at the end of September. The storage mechanism of large lakes and the regulation effect of reservoirs can produce low flow regimes that differ from those exhibited by rivers without such storage functions. For most rivers, low flow events of longer duration cause larger deficits, and events with large deficits are accompanied by lower minimum discharge. The deficit-to-demand ratio measures the extent to which river flow fails to satisfy water needs. Applying this index to rivers of the Mackenzie drainage shows the hazard of streamflow drought in the basin. Low flow attributes can be summarized by their probability distributions: Gumbel distribution for minimum discharge of events and generalized exponential distribution for event duration. By fitting theoretical distributions to recorded events, one can estimate the probability of occurrence of low flow events that did not occur in the historical past.

Conservation and Management of Rivers in India: Case-study of the River Yamuna

1993 ◽  
Vol 20 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Brij Gopal ◽  
Malavika Sah
Keyword(s):  
Water Quality ◽  
River Basin ◽  
River Flow ◽  
Drainage Basin ◽  
Management Strategies ◽  
Industrial Effluents ◽  
River System ◽  
Low Flow ◽  
Domestic Water ◽  
River Yamuna

The River Yamuna, originating in the Himalayas, is the largest tributary of the River Ganga (Ganges) into which it flows at Allahabad. Its drainage basin covers about 42% of the Ganga River basin and about 11% of India's total land area. The area of the Yamuna drainage basin is densely populated and under intensive agriculture, while industrial activity is also rapidly growing in it. Climatically, a large part of the basin is semi-arid, and the river-flow depends upon highly erratic monsoonal rains. Therefore, the River and its tributaries have been regulated for over a century by dams and barrages for domestic water-supply and irrigation.Besides increased flow-regulation, the River's system has been under increasing anthropogenic stress from discharge of—mostly untreated—domestic and industrial wastewaters, and from other activities in the basin. River Yamuna is severely polluted by domestic and industrial effluents especially from Delhi down to Agra. Water extraction and consequently low flow has affected the selfpurification capacity of the River. The greater inflow of River Chambal helps River Yamuna to recover to some extent after their confluence near Etawah.Studies of water quality and biota of the River Yamuna along its course during the past 30 years show rapid deterioration of water-quality, loss of fisheries, and significant changes in the biotic communities. In the manner of River Yamuna, its tributaries have also become increasingly polluted during the same period. There has, however, been little attention paid to the management of the River system and conservation of its resources, except for some efforts at the treatment of sewage effluents but emphasizing only water-quality. Ignoring the river-flood-plain interactions which play significant roles in the ecology of a river, most of the floodplain has been reclaimed by constructing high levees.We emphasize that the Yamuna River basin should be treated as one ecocomplex in developing appropriate management strategies, and that the conservation of waterquality and biota can be achieved through protection and better management of floodplains than has been practised to date.

scholarly journals Environmental flow assessments in estuaries related to preference of phytoplankton

2014 ◽  
Vol 18 (5) ◽  
pp. 1785-1791 ◽  
Author(s):  
Z. F. Yang ◽  
T. Sun ◽  
R. Zhao
Keyword(s):  
Environmental Factors ◽  
River Flow ◽  
Yellow River ◽  
Environmental Flows ◽  
River Estuary ◽  
High Amplitude ◽  
Environmental Flow ◽  
Negative Effects ◽  
Flood Pulses ◽  
Complex Relationships

Abstract. An approach to assess estuarine environmental flow based on phytoplankton preference, including the complex relationships between hydrological modifications and ecosystem biomass, was developed in this study. We initially established a relationship between biomass requirements for primary and higher nutritional level organisms based on the ecosystem nutritional energy flow principles. Subsequently, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, biomass responses to river discharge were established by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows were recommended for different fish biomass requirements. We used the Yellow River estuary as a case study; and May and June were identified as critical months for maintaining environmental flow. Temporal variation in natural river flow dynamics, which was used as a proxy for environmental flow, should be carefully examined in artificial hydrological regulation strategies, particularly during high-amplitude flood pulses, which might result in negative effects on phytoplankton groups, and subsequently higher aquatic species biomass.

Environmental Flows

2019 ◽  
Author(s):  
Ryan Morrison ◽  
Erin Bray
Keyword(s):  
River Flow ◽  
Environmental Flows ◽  
Spatial Scales ◽  
Flow Characteristics ◽  
River System ◽  
Environmental Flow ◽  
Flow Dynamics ◽  
Management Policy ◽  
River Health ◽  
Riverine Ecosystems

Environmental flows are commonly defined as the river-flow characteristics necessary to maintain the integrity of riverine ecosystems. The concept of environmental flows has evolved over the past half-century, beginning with the development of minimum instream flows necessary to protect a single fish species to current frameworks for holistically including all aspects of river health that depend on natural flow regimes. This also includes the interaction of terrestrial environments with riverine ecosystems during large flooding events. The challenges associated with defining and implementing environmental flows are numerous, and they sometimes lack data necessary to define flow-ecology relationships, appropriate temporal and spatial scales for environmental flow applications, and incorporate environmental flows into water management policy. Given these challenges, researchers and practitioners have made incredible advances in better understanding the relationships between river health and flow dynamics, including the links among flow, sediment, temperature, and human activities. In addition, computational advances have allowed researchers to more accurately model flow-habitat relationships at fine scales, providing a more complete understanding of the connection between flow and habitat needs for riverine species. All these advances benefit from holistic frameworks that guide environmental flow development and applications while considering the needs of other water uses in a river system. This article presents relevant studies regarding approaches for developing environmental flows, relationships between riverine ecology and flow dynamics, and policy frameworks and tools useful for implementing environmental flows in practice.

ASSESSMENT OF HYDROLOGICAL CHANGES IN THE ŠUŠVĖ RIVER

2015 ◽  
Author(s):  
Gražina ŽIBIENĖ ◽  
Alvydas ŽIBAS ◽  
Goda BLAŽAITYTĖ
Keyword(s):  
Hydrological Regime ◽  
Maximum Flow ◽  
Environmental Flow ◽  
Physical Structure ◽  
River Channels ◽  
Hydrologic Alteration ◽  
Water Conditions ◽  
Flow Components ◽  
The Impact ◽  
Large Floods

The construction of dams in rivers negatively affects ecosystems because dams violate the continuity of rivers, transform the biological and physical structure of the river channels, and the most importantly – alter the hydrological regime. The impact on the hydrology of the river can occur through reducing or increasing flows, altering seasonality of flows, changing the frequency, duration and timing of flow events, etc. In order to determine the extent of the mentioned changes, The Indicators of Hydrologic Alteration (IHA) software was used in this paper. The results showed that after the construction of Angiriai dam, such changes occurred in IHA Parameters group as: the water conditions of April month decreased by 31 %; 1-day, 3-days, 7-days and 30-days maximum flow decreased; the date of minimum flow occurred 21 days later; duration of high and low pulses and the frequency of low pulses decreased, but the frequency of high pulses increased, etc. The analysis of the Environmental Flow Components showed, that the essential differences were recorded in groups of the small and large floods, when, after the establishment of the Šušvė Reservoir, the large floods no longer took place and the probability of frequency of the small floods didn’t exceed 1 time per year.

Morphotectonic Analysis of Tanjung Bungo Area Based on Geological Structure Control, Central Sumatera Basin

2020 ◽  
Author(s):  
D., A., L., A. Putri
Keyword(s):  
Natural Resources ◽  
River Flow ◽  
Measurement Data ◽  
River System ◽  
Flow Patterns ◽  
Source Rocks ◽  
Aerial Photographs ◽  
Morphological Data ◽  
Tectonic Activity ◽  
Geological Structures

Tectonic activity in an area could result in various impacts such as changes in elevation, level of slope percentages, river flow patterns and systems, and the formation of geological structures both locally and regionally, which will form a new landscape. The tectonic activity also affects the stratigraphic sequences of the area. Therefore, it is necessary to study morphotectonic or landscape forms that are influenced by active tectonic activities, both those occur recently and in the past. These geological results help provide information of the potential of natural resources in and around Tanjung Bungo area. Morphological data are based on three main aspects including morphogenesis, morphometry, and morphography. The data are collected in two ways, the first is field survey by directly observing and taking field data such as measuring geological structures, rock positions, and outcrop profiles. The second way is to interpret them through Digital Elevation Model (DEM) and aerial photographs by analyzing river flow patterns and lineament analysis. The field measurement data are processed using WinTensor, Dips, and SedLog Software. The supporting data such as Topographic Maps, Morphological Elevation Maps, Slope Maps, Flow Pattern Maps, and Lineament Maps are based on DEM data and are processed using ArcGis Software 10.6.1 and PCI Geomatica. Morphotectonically, the Tanjung Bungo area is at a moderate to high-class level of tectonic activity taken place actively resulted in several joints, faults, and folds. The formation of geological structures has affected the morphological conditions of the area as seen from the development of steep slopes, structural flow patterns such as radial, rectangular, and dendritic, as well as illustrated by rough surface relief in Tanjung Bungo area. This area has the potential for oil and gas resources as indicated by the Telisa Formation, consisting of calcareous silts rich in planktonic and benthonic fossils, which may be source rocks and its contact with the Menggala Formation which is braided river system deposits that could be good reservoirs. Further research needs to be done since current research is only an interpretation of surface data. Current natural resources being exploited in Tanjung Bungo region are coals. The coals have thicknesses of 5-7 cm and are classified as bituminous coals.

Sources of Chlorophenolic Compounds to the Fraser River Estuary

1988 ◽  
Vol 23 (1) ◽  
pp. 55-68 ◽  
Author(s):  
J. H. Carey ◽  
J. H. Hart
Keyword(s):  
River Flow ◽  
River Estuary ◽  
Low Flow ◽  
Fraser River ◽  
Pulp Mills ◽  
Flow Conditions ◽  
Downstream Site ◽  
Upstream Site ◽  
The North ◽  
Main River

Abstract The identity and concentrations of chlorophenolic compounds in the Fraser River estuary were determined under conditions of high and low river flow at three sites: a site upstream from the trifurcation and at downstream sites for each main river arm. Major chlorophenolics present under both flow regimes were 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), pentachlorophenol (PCP), tetrachloroguaiacol (TeCG) and a compound tentatively identified as 3,4,5-trichloroguaiacol (3,4,5-TCG). Under high flow conditions, concentrations of the guaiacols were higher than any of the Chlorophenols and concentrations of all five chlorophenolics appeared to correlate. Under low flow conditions, concentrations of chloroguaiacols were higher than Chlorophenols at the upstream site and at the downstream site on the Main Arm, whereas at the downstream site on the North Arm, concentrations of 2,3,4,6-TeCP and PCP were higher than the chloroguaiacols in some samples. Overall, the results indicate that pulp mills upstream from the estuary are important sources of chlorophenolics to the estuary under all flow conditions. Additional episodic inputs of 2,3,4,6-TeCP and PCP from lumber mills occur along the North Arm. When these inputs occur, they can cause the concentrations of Chlorophenols in the North Arm to exceed provisional objectives. If chloroguaiacols are included as part of the objective, concentrations of total chlorophenolics in water entering the estuary can approach and exceed these objectives, especially under low flow conditions.

Relationship of upstream migrating adult Atlantic salmon (Salmo salar) and stream discharge within Catamaran Brook, New Brunswick

2007 ◽  
Vol 64 (3) ◽  
pp. 563-573 ◽  
Author(s):  
Sean C Mitchell ◽  
Richard A Cunjak
Keyword(s):  
Body Size ◽  
Atlantic Salmon ◽  
New Brunswick ◽  
Salmo Salar ◽  
Predictive Ability ◽  
River System ◽  
Low Flow ◽  
Stream Discharge ◽  
Atlantic Salmon Salmo Salar ◽  
Adult Abundance

Stream discharge has long been associated with abundance of returning adult spawning salmonids to streams and may also affect body size distribution of adult salmon as low flows interfere with returns of larger-bodied fish. We examined these relationships of abundance and body size within Catamaran Brook, a third-order tributary to the Miramichi River system of New Brunswick, Canada, to investigate the causes of a declining trend in annual returns of Atlantic salmon (Salmo salar) to this stream. Regression models of adult abundance, proportion of the run as grilse, and body size of returning adults as functions of maximum daily stream discharge during the period of upstream spawner migration were constructed. Adult abundance shows a logarithmic relationship with stream discharge and provides good predictive ability, while appearing to not be significantly related to adult abundance in the larger Miramichi system. The proportion as grilse in the run and female body size are also logarithmically related to stream discharge, with low flow years being very influential in the regressions. These relationships of Atlantic salmon population abundance and body size characteristics have implications with respect to stock integrity and production of the following generation.

scholarly journals Analysis of Flood Vulnerability as a Support to Water Sensitive Urban Design Planning in Klaten Regency

2021 ◽  
Vol 26 (2) ◽  
pp. 183-193
Author(s):  
Desyta Ulfiana ◽  
Yudi Eko Windarto ◽  
Nurhadi Bashit ◽  
Novia Sari Ristianti
Keyword(s):  
Land Use ◽  
Urban Design ◽  
Flood Hazard ◽  
Flood Management ◽  
Flood Vulnerability ◽  
Geological Conditions ◽  
Order Preference ◽  
Water Sensitive Urban Design ◽  
High Flood ◽  
High Level

Klaten Regency is one of the regions that has a high level of flood vulnerability. The area of Klaten Regency which is huge and has diverse characteristics makes it difficult to determine an appropriate flood management model. Water Sensitive Urban Design (WSUD) is a model that focuses on handling water management problems with environmentally friendly infrastructure. Therefore, an analysis is carried out to determine the level of flood vulnerability and factors causing flooding to plan a WSUD design that is suitable for each sub-districts of Klaten Regency. The Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods are used to help the analysis. Aspects used as criteria are rainfall, slope, soil type, geological conditions, and land use. Based on the analysis, it could be concluded that Klaten Regency has two sub-districts with high flood hazard category, 21 sub-districts with medium category, and three sub-districts with low category. Bayat and Cawas are sub-districts that have a high level of flood vulnerability category. Meanwhile, Kemalang, Karangnongko and Polanharjo are districts with a low level of flood vulnerability category. The main factors causing flooding in Klaten Regency are slope and land use.

scholarly journals Resolving conflicts over trans-boundary rivers using bankruptcy methods

2013 ◽  
Vol 10 (11) ◽  
pp. 13855-13887 ◽  
Author(s):  
M. Zarezadeh ◽  
K. Madani ◽  
S. Morid
Keyword(s):  
Temporal Distribution ◽  
Stability Index ◽  
River System ◽  
Planning Horizon ◽  
Climatic Conditions ◽  
Index Method ◽  
Allocation Rules ◽  
Available Water ◽  
Time Sensitivity ◽  
Solution Methods

Abstract. A bankruptcy approach is proposed for resolving trans-boundary rivers conflicts in which the total water demand or claim of the riparian parties is more than the available water. Bankruptcy solution methods can allocate the available water to the conflicting parties with respect to their claims. Four bankruptcy rules are used here to allocate the available water to the riparian parties. Given the non-uniform spatial and temporal distribution of water across river basins, bankruptcy optimization models are proposed to allocate water based on these rules with respect to time sensitivity of water deliveries during the planning horizon. Once allocation solutions are developed, their acceptability and stability must be evaluated. Thus, a new stability index method is developed for evaluating the acceptability of bankruptcy solutions. To show how the bankruptcy framework can be helpful in practice, the suggested methods are applied to a real-world tarns-boundary river system with eight riparians under various hydrologic regimes. Stability analysis based on the proposed stability index method suggests that the acceptability of allocation rules is sensitive to hydrologic conditions and demand values. This finding has an important policy implication suggesting that fixed allocation rules and trans-boundary treaties may not be reliable for securing cooperation over trans-boundary water resources as they are vulnerable to changing socio-economic and climatic conditions as well as hydrologic non-stationarity.

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