Increased River Flow Research Articles

Climigration? Population and climate change in Arctic Alaska.

Residents of towns and villages in Arctic Alaska live on “the front line of climate change.” Some communities face immediate threats from erosion and flooding associated with thawing permafrost, increasing river flows, and reduced sea ice protection of shorelines. The term climigration, referring to migration caused by climate change, originally was coined for these places. Although initial applications emphasized the need for government relocation policies, it has elsewhere been applied more broadly to encompass unplanned migration as well. Some historical movements have been attributed to climate change, but closer study tends to find multiple causes, making it difficult to quantify the climate contribution. Clearer attribution might come from comparisons of migration rates among places that are similar in most respects, apart from known climatic impacts. We apply this approach using annual 1990–2014 time series on 43 Arctic Alaska towns and villages. Within-community time plots show no indication of enhanced out-migration from the most at-risk communities. More formally, there is no significant difference between net migration rates of at-risk and other places, testing several alternative classifications. Although climigration is not detectable to date, growing risks make either planned or unplanned movements unavoidable in the near future.

Phosphorus in the Minnesota River Basin: The debate over its source and ways to mitigate impacts

Phosphorus in the Minnesota River Basin: The debate over its source and ways to mitigate impacts

Increasing River Flow Expands Riparian Habitat: Influences of Flow Augmentation on Channel Form, Riparian Vegetation and Birds Along the Little Bow River, Alberta

AbstractWith river regulation, water withdrawal is common, reducing instream flows. The opposite alteration, flow augmentation, is less common and could reveal a mechanistic coordination between flow regime, channel form, and riparian ecosystems. The Little Bow River, a naturally intermittent prairie stream in Southern Alberta, has experienced flow augmentation since the late 1890s, and the Little Bow/Highwood Project of 2004 enabled a tripling of diversion flows from 2.9 to 8.5 m3/s. We investigated the subsequent responses by assessing the channel form and riparian vegetation based on aerial photographs taken in 2000 versus 2010, and riparian birds were assessed between 2005 and 2013 to investigate associations with riparian vegetation. Following recent flow augmentation, the mean channel width increased from 12.2 to 13.5 m, while sinuosity was relatively unchanged. Streamside zones with true willows (especially Salix exigua and Salix bebbiana) increased from 7 to 11% of the river corridor, and the facultative riparian wolf willow (Elaeagnus commutata) zones increased from 16 to 20%, while grassy zones decreased from 64 to 52%. Avian species richness and Shannon–Wiener index increased, while species evenness was relatively unaltered, suggesting an increase of rarer bird species in response to the increased habitat structure and diversity following the expansion of riparian shrubs and woodland. This study revealed responses to the recent flow augmentation over the first decade of implementation, and alterations following flow augmentation would likely continue for decades until the river and riparian zones adjust to the new flow regime. Copyright © 2016 John Wiley & Sons, Ltd.

Elemental Analysis of River Water from Transylvania, Romania, by Inductively Coupled Plasma Mass Spectrometry and Chemometrics

ABSTRACTThe objectives of this study were to determine metals in water samples obtained from three main rivers from Transylvania in two seasons and to apply chemometric methods for further interpretation. Inductive coupled plasma–mass spectrometry was used for these analyzes. Chemometric techniques, including analysis of variance, Pearson correlation, cluster analysis, and principal component analysis were applied for assessing variation in the results. Analysis of variance highlighted elements that were influenced by increased river flow in the wet season, and Pearson correlation established a positive correlation between elements. Cluster analysis showed a number of sample points in two main clusters according to their loading. Principal component analysis extracted five main components with each characterized by specific metals. These results are useful in monitoring studies because the river management plan may be improved by reducing the number of sampling points and monitoring parameters to those that are representative of each river basin.

Limnological assessment of the meteo-hydrological and physicochemical factors for summer cyanobacterial blooms in a regulated river system

This study aimed to explain how the changes in certain hydrological, meteorological and physicochemical factors influence the cell density of the cyanobacteria Microcystis aeruginosa in the Nakdong River. Occurrence patterns of M. aeruginosa were analyzed between 1993 and 2010 (N =96) using a self-organizing map. The cell density of M. aeruginosa was sensitive to certain meteorological, hydrological and physicochemical factors. In addition, our clustering analysis results identified specific limnological features under different environmental conditions. Cluster 1 suggested that high rainfall and increased river flow, dam discharge, total phosphorous and phosphate concentrations were associated with low M. aeruginosa cell density (June–July; monsoon season). However, cluster 2 suggested low irradiance since water temperature decreases with irradiation time, and thus low M. aeruginosa cell density (April–June and after November). Finally, cluster 3 was indicative of high water temperature and irradiance, increased irradiation time, low phosphate and nitrate concentrations, and high M. aeruginosa cell density (August, after the monsoon season). Taken together, these results suggest that rainfall, river flow, water temperature and nutrient concentration (i.e. , phosphates and nitrates) were the primary factors that affected cyanobacterial bloom occurrence in the Nakdong River. M. aeruginosa blooms can be suppressed by employing an integrated water resource management program that accommodates meteo-hydrological factors along with the effective control of exogenous nutrient sources.

Analysis of Environmental Factors Influencing Salinity Patterns, Oyster Growth, and Mortality in Lower Breton Sound Estuary, Louisiana, Using 20 Years of Data

ABSTRACT La Peyre, M.K.; Geaghan, J.; Decossas, G., and La Peyre, J.F., 2016. Analysis of environmental factors influencing salinity patterns, oyster growth, and mortality in lower Breton Sound Estuary, Louisiana, using 20 years of data. Freshwater inflow characteristics define estuarine functioning by delivering nutrients, sediments, and freshwater, which affect biological resources and ultimately system production. Using 20 years of water quality, weather, and oyster growth and mortality data from Breton Sound Estuary (BSE), Louisiana, we examined the relationship of riverine, weather, and tidal influence on estuarine salinity, and the relationship of salinity to oyster growth and mortality. Mississippi River discharge was found to be the most important factor determining salinity patterns over oyster grounds within lower portions of BSE, with increased river flow associated with lowered salinities, while easterly winds associated with increased salinity were less influential. These patterns were consis...

South Asia river-flow projections and their implications for water resources

Abstract. South Asia is a region with a large and rising population, a high dependence on water intense industries, such as agriculture and a highly variable climate. In recent years, fears over the changing Asian summer monsoon (ASM) and rapidly retreating glaciers together with increasing demands for water resources have caused concern over the reliability of water resources and the potential impact on intensely irrigated crops in this region. Despite these concerns, there is a lack of climate simulations with a high enough resolution to capture the complex orography, and water resource analysis is limited by a lack of observations of the water cycle for the region. In this paper we present the first 25 km resolution regional climate projections of river flow for the South Asia region. Two global climate models (GCMs), which represent the ASM reasonably well are downscaled (1960–2100) using a regional climate model (RCM). In the absence of robust observations, ERA-Interim reanalysis is also downscaled providing a constrained estimate of the water balance for the region for comparison against the GCMs (1990–2006). The RCM river flow is routed using a river-routing model to allow analysis of present-day and future river flows through comparison with available river gauge observations. We examine how useful these simulations are for understanding potential changes in water resources for the South Asia region. In general the downscaled GCMs capture the seasonality of the river flows but overestimate the maximum river flows compared to the observations probably due to a positive rainfall bias and a lack of abstraction in the model. The simulations suggest an increasing trend in annual mean river flows for some of the river gauges in this analysis, in some cases almost doubling by the end of the century. The future maximum river-flow rates still occur during the ASM period, with a magnitude in some cases, greater than the present-day natural variability. Increases in river flow could mean additional water resources for irrigation, the largest usage of water in this region, but has implications in terms of inundation risk. These projected increases could be more than countered by changes in demand due to depleted groundwater, increases in domestic use or expansion of water intense industries. Including missing hydrological processes in the model would make these projections more robust but could also change the sign of the projections.

Impact of advection loss due to wind and estuarine circulation on the timing of the spring phytoplankton bloom in a fjord

AbstractA coupled biophysical model is used to explore the physical controls involved in the timing of the spring phytoplankton bloom in fjords. Observations from Rivers Inlet, British Columbia, are used to force and evaluate the model. It is found that the interannual variation in timing is due primarily to variations in retention, in particular, to variations in horizontal advection out of the fjord. The two dominant processes are (i) strong outflow winds rapidly advecting the surface layer and thus the phytoplankton population out of the fjord and (ii) losses due to high river flux increasing the estuarine circulation. Both processes delay the timing of spring bloom. Smaller effects on the interannual variation are due to increased wind mixing which deepens the mixing layer and reduces light to phytoplankton, and increased river flow which increases the stratification and decreases the mixing layer depth. Observed interannual variations in cloudiness were small. Strong outflow winds are common in winter along the British Columbia coast, but generally cease after the spring wind transition. Thus, observed interdecadal variations in the spring transition date probably imply strong variations in the timing of spring phytoplankton blooms in British Columbia fjords.

A tale of two basins: An integrated physical and biological perspective of the deep Arctic Ocean

A tale of two basins: An integrated physical and biological perspective of the deep Arctic Ocean

Influence of solar activity on global large rivers runoff trends

The physical basis of the influence of solar activity on the climate is evident. The sun’s heat and light energy warms the land surface and oceans and they radiate heat back into the air above. It is believed that increase of solar activity leads to a rise in atmospheric temperature, intensification of the hydrological cycle and consequently to an increase in river flow. The impacts of climate change have led to an increase in global and continental runoff in the last century (Labat et al. 2004). Observations also show a long-term increase trend of solar activity over the period 1855–1996 (Krivova and Solanki 2004). This phenomenon initiated a project to test the hypothesis: influence of solar activity on rivers discharge.

Realised and predicted changes in the invertebrate benthos after restoration of connectivity to the floodplain of a large river

Summary River–floodplain interactions (i.e. lateral connectivity) are a major driver of the structure and function of the biota in floodplain waterbodies. Therefore, the enhancement of lateral connectivity is a key focus of large river restoration. The Rhône River restoration project in France includes an array of floodplain habitats and restoration measures, offering opportunities to test the predictability of changes in taxon abundance after connectivity restoration. Quantitative samples of benthic macroinvertebrates taken before restoration were used to derive generalised additive models (GAMs) relating the density of taxa to an index of lateral connectivity. The index combined the diversity of sediment grain size, its organic content, vegetation cover and the water's electrical conductivity. GAMs were used to predict changes in taxon density and between‐site (i.e. beta) diversity 2 and 4 years after restoration at 34 sites (14 unrestored, eight reconnected to the river, six dredged, six restored by increasing river flow). Observed post‐restoration changes included an increase in the density of rheophilous taxa and an increase of beta‐diversity among restored sites. Fifty‐four GAMs (27% of the taxa) were selected for post‐restoration predictions. Predictions from these models matched observations for a set of Trichoptera and other taxa with large density changes after restoration. The quality of predictions of density changes was poor on average among sites, but higher for sites where large changes in lateral connectivity occurred. Taxon‐level predictions partly explained increased beta‐diversity in restored sites, suggesting that predictions based on a subset of individual taxa can be used to predict community‐level changes. Our models can guide restoration measures in the Rhône and other rivers. Our results also show the benefit of diversifying restoration actions at the scale of entire floodplains. Post‐restoration trajectories should be monitored over long periods to improve the identification of the key environmental predictors of biotic changes, especially at the less connected floodplain sites.

The winter storms of 2013/2014 in the UK: hydrological responses and impacts

This paper outlines the hydrological aspects of the 2013/2014 winter flooding in the UK, as well as the impacts. The episode is considered in a long-term historical context and wider issues raised by the flood events are discussed briefly.

Lake Eyre golden perch (Macquaria sp.) spawning and recruitment is enhanced by flow events in the hydrologically variable rivers of Lake Eyre Basin, Australia

Understanding the links between fish recruitment and riverine flows is integral for setting priorities for river-management strategies, particularly in hydrologically variable and unpredictable arid and semi-arid zone rivers. In the present study, we used daily and annual otolith age estimates to identify relationships between riverine flow and spawning and recruitment of Lake Eyre golden perch (Macquaria sp.); an endemic fish of the Lake Eyre Basin, central Australia. We found a close association between Lake Eyre golden perch spawning and periods of increased river flow, with most of spawning occurring 0–35 days after the start of these flow events. Spawning occurred throughout the year but was commonly observed during the first flow events proceeding consecutive months of no-flow when water temperatures exceeded 26°C. Spawning was not dependent on floodplain inundation, with most spawning occurring during within-channel flow events. Annual average year-class strength was related to the number of flow events per year, but not total annual discharge, or the number of low-flow days per year. These results highlight the importance of natural within-channel flow patterns to Lake Eyre golden perch spawning and recruitment and demonstrate the importance of maintaining the natural flow regime of Australia’s arid- and semi-arid-zone rivers.

Twenty first century climatic and hydrological changes over Upper Indus Basin of Himalayan region of Pakistan

This study is based on both the recent and the predicted twenty first century climatic and hydrological changes over the mountainous Upper Indus Basin (UIB), which are influenced by snow and glacier melting. Conformal-Cubic Atmospheric Model (CCAM) data for the periods 1976–2005, 2006–2035, 2041–2070, and 2071–2100 with RCP4.5 and RCP8.5; and Regional Climate Model (RegCM) data for the periods of 2041–2050 and 2071–2080 with RCP8.5 are used for climatic projection and, after bias correction, the same data are used as an input to the University of British Columbia (UBC) hydrological model for river flow projections. The projections of all of the future periods were compared with the results of 1976–2005 and with each other. Projections of future changes show a consistent increase in air temperature and precipitation. However, temperature and precipitation increase is relatively slow during 2071–2100 in contrast with 2041–2070. Northern parts are more likely to experience an increase in precipitation and temperature in comparison to the southern parts. A higher increase in temperature is projected during spring and winter over southern parts and during summer over northern parts. Moreover, the increase in minimum temperature is larger in both scenarios for all future periods. Future river flow is projected by both models to increase in the twenty first century (CCAM and RegCM) in both scenarios. However, the rate of increase is larger during the first half while it is relatively small in the second half of the twenty first century in RCP4.5. The possible reason for high river flow during the first half of the twenty first century is the large increase in temperature, which may cause faster melting of snow, while in the last half of the century there is a decreasing trend in river flow, precipitation, and temperature (2071–2100) in comparison to 2041–2070 for RCP4.5. Generally, for all future periods, the percentage of increased river flow is larger in winter than in summer, while quantitatively large river flow was projected, particularly during the summer monsoon. Due to high river flow and increase in precipitation in UIB, water availability is likely to be increased in the twenty first century and this may sustain water demands.

Influence of flow on the migration and capture of juvenile galaxiids in a large river system

The upstream migrations of juvenile galaxiids, or ‘whitebait’, form the basis of an important New Zealand fishery. This study used mark and recapture experiments with juvenile galaxiids in the Mokau River to examine the effect of flow on migration and capture rates. Recapture rates of marked fish ranged between 2.7% and 26.9%, with the proportion of fish recaptured positively correlated with increasing river flow. Increasing river flow negatively affected the upstream migration rates of fish. Migration rates through the tidal zone could be rapid, with fish travelling upstream at speeds up to 1.4 km h−1 within 24 h of release. However, not all marked fish exhibited rapid upstream movement. Fish captured on the second day following release had travelled at slower speeds up to 0.7 km h−1, suggesting that these fish did not initiate their migration on the tidal cycle subsequent to their liberation. A small proportion of fish were also found to travel up to 15 km downstream following release at the upper end of the tidal zone. Results indicated that some fish migrated on both diurnal and nocturnal tidal cycles. Nocturnal migrations by juvenile galaxiids could reduce capture rates and increase recruitment, especially in smaller rivers and streams where fish can pass the tidal fishing area on a single overnight tidal cycle. These results have management implications for river systems where juvenile galaxiids are exposed to multiple days fishing pressure, as reducing fishable zones could be one means of reducing pressure on unstable or declining galaxiid populations.

Effect of different river flow rates on biomarker responses in common carp (Cyprinus carpio)

The present study investigated effects of different river flow rates on basal activities of selected biomarkers and the occurrence of oxidative stress in the common carp (Cyprinus carpio). Juvenile carp were exposed to different river flow rates (5–120cm/s) by caging for 3 weeks. After this period, one half of the fish were sacrificed and used for analysis. The other half received a single intraperitoneal injection of 3-methylcholanthrene (3-MC) and after 6 days were sacrificed and used for analysis. In order to investigate whether the physical activity of carp in the environment will influence the condition status of carp, following biomarkers were measured – activities of glutathione S-transferase (GST), catalase (CAT) and ethoxyresorufin-O-deethylase (EROD) and concentration of protein carbonyls (PC). The results showed that different flow rates significantly influenced biochemical biomarkers. The basal activity of GST did not change significantly after exposure to different river flow rates, whereas the activity of CAT increased with increasing river flow rates. The application of 3-MC caused significant increases in GST and CAT activities, but there were no difference between 3-MC control and 3-MC different flow rates. The occurrence of oxidative stress as a result of exposure to increased physical activity, i.e. increased river flow rates, was confirmed by measurement of PC levels – the level of PC increased with increasing river flow rates. Measurement of EROD basal activity showed that at lower river flow rates the EROD activity increased and at higher river flow rates decreased towards control levels demonstrating a close relationship between oxidative stress, PC levels and EROD activity. Obviously, biomarker responses in carp of different condition status can differ substantially. It can be concluded that flow rate may be an important factor in biomonitoring of rivers using biomarkers and since at different locations river water flow rate can vary significantly, the site selection is extremely important for proper design of river biomonitoring studies involving caging.

Future variability of solute transport in a macrotidal estuary

The physical controls on salt distribution and river-sourced conservative solutes, including the potential implications of climate change, are investigated referring to model simulations of a macrotidal estuary. In the UK, such estuaries typically react rapidly to rainfall events and, as such, are often in a state of non-equilibrium in terms of solute transport; hence are particularly sensitive to climate extremes. Sea levels are projected to rise over the 21st century, extending the salinity maximum upstream in estuaries, which will also affect downstream solute transport, promoting estuarine trapping and reducing offshore dispersal of material. Predicted ‘drier summers’ and ‘wetter winters’ in the UK will influence solute transport further still; we found that projected river flow climate changes were more influential than sea-level rise, especially for low flow conditions. Our simulations show that projected climate change for the UK is likely to increase variability in estuarine solute transport and, specifically, increase the likelihood of estuarine trapping during summer, mainly due to drier weather conditions. Future changes in solute transport were less certain during winter, since increased river flow will to some extent counter-act the effects of sea-level rise. Our results have important implications for non-conservative nutrient transport, water quality, coastal management and ecosystem resilience.

Relação entre vazão e qualidade da água em uma seção de rio

O objetivo do presente trabalho foi avaliar a dinâmica de determinadas variáveis de qualidade da água em função da vazão, em uma seção transversal do rio Catolé Grande próxima ao ponto de captação de água para abastecimento do município de Itapetinga-BA. Amostras de água foram coletadas por integração vertical, em diferentes meses, correspondente a diferentes vazões. Nessas amostras foram realizadas análises de potencial hidrogeniônico (pH), turbidez, sólidos totais dissolvidos, salinidade e fósforo total. A velocidade do fluxo foi medida com o auxílio do molinete e a vazão foi calculada pelo produto da velocidade pela área da seção. Os resultados apontaram que a salinidade, os sólidos totais dissolvidos e a turbidez apresentaram comportamentos semelhantes, aumentando linearmente com o incremento da vazão, enquanto o pH apresentou tendência contrária. As concentrações de fósforo apresentaram comportamento exponencial em função da vazão, sendo que os valores médios desta variável ultrapassaram os limites estipulados pela resolução CONAMA 357 para a pior classe de qualidade de água doce.

Challenge and response in the Indus Basin

The authors examine the complex history of the development of the Indus Basin and the challenges faced by Pakistan during the evolution of the Indus Basin Irrigation System and the country's responses to date. The Indus river system must meet the multiple needs of agriculture, energy and flood security. Pakistan's constitutional structure, in which the federation shares overall responsibility for the operation of the Indus with the provinces, poses unique management and implementation challenges. What are the institutional arrangements Pakistan needs to address the challenges to the Indus Waters Treaty it signed with India in 1960? How is the country going to regulate the use of over-abstraction in the basin with the increased reliance on groundwater to maintain agricultural productivity? What are the institutional mechanisms in place to manage increased river flow variations from glacial melt as a result of climate change and for coping with devastating floods? At the same time, is the country maintaining adequate environmental flows to its delta? Provincial mistrust and a lack of institutional capacity underpins the history of the Indus in Pakistan with the Interprovincial Water Accord 1991 serving as a ray of hope on which to build a new institutional architecture of cooperation.

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

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.