Hydrological Regime Of Rivers Research Articles

How to comprehensively evaluate river discharge under the influence of a dam

The dams in the upper reaches of the Yangtze River are highly concentrated. Dam construction can effectively solve water shortage problems; however, the natural hydrological regimes of rivers have changed to varying degrees under the influence of water conservancy projects. In this study, a comprehensive method is proposed to analyze the hydrological regime changes in a river impacted by a dam through the evaluation of hydrological periodicity, hydrological frequency and hydrological parameters. Hydrological periodicity is used to evaluate the time series from the vertical multiyear perspective, while hydrological frequency is used to evaluate the time series from the horizontal one-year perspective. The two parameters have complementary roles. The indicators of hydrologic alteration and environmental flow component parameters are used to analyze the changes in various hydrological factors affected by the dam. The results demonstrate that the construction of dams can change the multiyear periodicity of the flow and reduce the peak flow. As a result, downstream fish may be unable to sense the reduced floods and fail to spawn. The indicators of hydrologic alteration and environmental flow component parameters can complement each other and can be used to evaluate changes in a hydrological regime influenced by a dam. This comprehensive method can be used to analyze how the hydrological regime is affected by this dam.

Does global change increase the risk of maladaptation of Atlantic salmon migration through joint modifications of river temperature and discharge?

In freshwater ecosystems, water temperature and discharge are two intrinsically associated triggers of key events in the life cycle of aquatic organisms such as the migration of diadromous fishes. However, global changes have already profoundly altered the thermal and hydrological regimes of rivers, affecting the timing of fish migration as well as the environmental conditions under which it occurs. In this study, we focused on Atlantic salmon (Salmo salar), an iconic diadromous species whose individuals migrate between marine nursery areas and continental spawning grounds. An innovative multivariate method was developed to analyse long-term datasets of daily water temperature, discharge and both salmon juvenile downstream and adult upstream migrations in three French rivers (the Bresle, Oir and Nivelle rivers). While all three rivers have gradually warmed over the last 35 years, changes in discharge have been very heterogeneous. Juveniles more frequently used warmer temperatures to migrate. Adults migrating a few weeks before spawning more frequently used warm temperatures associated with high discharges. This has already led to modifications in preferential niches of both life stages and suggests a potential mismatch between these populations' ecological preference and changes in their local environment due to global change.

Стратегия сохранения биологического разнообразия, охраны лесных и водных ресурсов бореальной зоны

The article introduces a new system of boreal forest management that aims at preserving the biodiversity, resources, and ecological potential. The research results can help to develop regional strategies for large forest regions that experience significant man-made impact. Antropogenic factors destroy the resource potential of forests, as well as their biological diversity, not to mention the hydrological regime of rivers. The paper features various measures that make it possible to avoid risks and ensure sustainable long-term use of forests.

Forest Husbandry in the Khabarovsk Territory: Environmental Risks and Ways of Addressing Them

The Khabarovsk Territory is characterized by considerable reserves of the forest resources. Their share is 18 % of the forested area of the Far Eastern Federal District and 25 % of the timber reserves. In the region, the forestry sector is the branch of national economic specialization which is associated with the export orientation of the forestry products. In this paper, the factors that determine environmental risks during logging are analyzed, including a low level of control of felling, violations of technologies, rules and standards for felling in the main-use forests, an increase in a fire hazard, violation of the hydrological regime of rivers, the development of erosion processes, pollution of aquatic ecosystems, expansion of road networks, increased poaching pressure on previously inaccessible forest areas, etc. Environmental problems caused by these factors are associated with a decrease in the resources, the ecological functions and the biological diversity of forests, the destruction of possibilities for traditional forest management, and the destruction and transformation of historically formed ecosystems. An unbiased inventory of the forest resources, their quantity and quality assessment, a governmental monitoring of the state of forest ecosystems, support for alternative types of forest use (recreational, tourist, etc.) are of paramount importance in solving these problems.

What affects the hydrological response of rain-on-snow events in low-altitude mountain ranges in Central Europe?

Rain-on-snow (ROS) events influence the hydrological regime of rivers in regions with seasonal snow cover. Although ROS events are often related to floods, they do not always cause severe runoff. During ROS, the snowpack has an ambiguous effect on runoff generation; it can either store a significant portion of rain or amplify runoff by additional snowmelt. There is a need to understand under what circumstances ROS events produce runoff. We analysed eleven years of hourly meteorological, snow water equivalent and streamflow data from 15 catchments located in two mountain ranges in Czechia. We identified 611 ROS events which were further analysed and classified using selected meteorological, snow and runoff indices. The analysis of the runoff response of all ROS events revealed that only 5% of them resulted in high runoff exceeding the 1-year return period, but most of the events (82%) did not cause any significant runoff increase. Employing self-organising maps enabled us to categorise the events and better understand what combination of hydrometeorological characteristics leads to various runoff responses. High volumes of rain together with low snow cover were identified as important factors in the generation of high runoffs. In contrast, a deep and extended snowpack affected by rain under low air temperatures usually caused lower runoffs. The results of this study showed the importance of the snowpack, which can often prevent extreme runoff even when a large amount of rainfall occurs. Understanding the hydrological regime of ROS is becoming even more important with the ongoing decline of the snowfall fraction and subsequent changes in snow storage.

Uncertainty analysis for evaluating flow regime alteration of Jinsha River based on Indicators of Hydrologic Alteration

ABSTRACT The uncertain relationship between data length and evaluation of hydrological alteration has perplexed researchers. In this study, the length of record (LOR) method is applied to analyse the uncertainty in the impact of different data lengths on the Indicators of Hydrologic Alteration (IHA) evaluation in the Jinsha River. The results indicate: (1) For the pre-impact period, a daily streamflow data length of 20 years should be required to meet all the indicators, but 5–10 years of data could be sufficient when analysing some specific indicators. (2) A logarithmic correlation was found between the LOR results and the coefficient of variation (CV) of the IHA statistics, which can be considered reference factors to reduce the computational complexity when we expect to obtain LOR results from other nearby hydrological stations. (3) For the post-impact period, using a data length of 10 years is sufficient to evaluate the impact of large reservoirs on the river hydrological regime, and the actual alteration of hydrological regime would be overestimated by using a shorter data length.

The Long‐Term Response of Alternate Bars to the Hydrological Regime

AbstractMigrating bars are large‐scale, alternate bedforms that often develop in channelized river reaches, as a consequence of an intrinsic instability of the erodible channel bed. Their behavior under steady flow conditions has been widely investigated by means of theoretical, experimental, and numerical models, which revealed that bar formation occurs when the width‐to‐depth ratio of the channel exceeds a critical threshold value. Conversely, no much information is available about the long‐term, average characteristics of alternate bars in the case of a complex flow regime, which makes the width‐to‐depth ratio highly variable in time. Starting from the state‐of‐the‐art theoretical models of bar dynamics, we propose a novel methodology to determine the long‐term bar response to the hydrological river regime and the associated “bar‐forming” discharge that, if applied steadily, would produce the same morphological response. We derive a generalized criterion to define whether bars are expected to form and to estimate the long‐term bar topography, depending on flow probability density function and channel characteristics (width, slope and sediment size). Our procedure differs from the classical methods to define formative discharge, inasmuch as it accounts for the specific and reversible response of bar topography to the different flow stages that compose the hydrological regime. Application to four different gravel bed reaches in the Alpine region shows the capability of the procedure to interpret remarkably different riverbed morphologies and to provide a reasonable prediction of the observed bar height, thus suggesting its potential to analyze long‐term morphological trajectories following hydrological alterations and river restoration projects.

Development of a comprehensive framework for quantifying the impacts of climate change and human activities on river hydrological health variation

Climate change and human activities have together altered the river hydrological regime and consequently threatened the health of river ecosystems. Quantifying the impact of climate change and human activities on river hydrological health regimes is essential for water resource management and river ecology protection. Although previous studies have analysed the hydrologic alterations using some indicators, separating effects of climate change and human activities on river hydrological health is needed for developing adaptive measures to protect the ecosystem of river basins. In this study, a comprehensive assessment framework for quantifying climatic and anthropogenic influences on river hydrological health variation was proposed. The framework consists of the following steps: (1) the reconstruction of natural river streamflow using the variable infiltration capacity (VIC) hydrological model, (2) calculation of river hydrological health through the ecological flow threshold method, and (3) quantification of the impacts of climate change and human activities on river hydrological health using the ‘observed–simulated’ comparison approach. The semi-arid Laohahe Basin in northern China, which consists of three human-influenced catchments (Taipingzhuang, Chifeng, and Xinglongpo) and one natural catchment (Xiquan), was selected as the case study area. The case study demonstrated that the proposed procedure is efficient in quantifying climatic and anthropogenic influences on river hydrological health. The results revealed that the hydrological health level has significantly declined in the three human-influenced catchments for the human-influenced period (1980–2016), particularly in the 2000 s and 2010 s, where it degraded much more severely. Whereas, the relatively adequate rainfall in the 1990 s maintained the river hydrological health at a good status. The quantitative evaluation showed that human activities were the main driving factors for the hydrological health degradation during the whole human-influenced period, with contributions of 80.8%, 91.9%, and 86.0% for the Taipingzhuang, Chifeng, and Xinglongpo catchments, respectively. Widespread artificial water withdrawal and reservoir operation were the two crucial human activities that caused the degradation of river hydrological health for the studied catchment. The proposed procedure and findings of this study not only help in deeper understanding of the evolutionary characteristics and driving mechanisms of river hydrological health in a changing environment in general, but also provide scientific basis for local water resources management and river ecosystems protection.

The number of insects of midges complex and ratio of its various components in the forest-steppe zone of the Tyumen Region

The purpose of the research is comparing abundance levels of blood-sucking dipterans in the forest-steppe zone of the Tyumen Region for 8 years with different meteorological conditions.Materials and methods. The studies were carried out in 2006 and 2013–2019 in vicinity of the villages of Isetskoe and Barkhatovo, Isetsky District, Tyumen Region. Tabanid flies were collected and counted using funnel-shaped traps permanently on the same pasture on a regular basis once every 5–7 days during the entire emergence period. When counting the number of mosquitoes, midges and sandflies, we used a net with removable bags. Each count included 10 sweeps with a motion of the figure eight "around itself" in 10 replications.Results and discussion. The abundance of blood-sucking dipterans is largely determined by natural and climatic conditions and a hydrological regime of rivers, and is liable to significant fluctuations. The maximum abundance of gnats was recorded in 2014, the minimum in 2006. In comparing the average number for seasons with maximum and minimum abundance, a difference of 3.7 times was found. The abundance level and ratio of individual components of the midges complex depending on the season also underwent significant changes. In collected insects, midges dominated in 2006 and 2014, and mosquitoes in 2013 and in 2015–2019. Meteorological and hydrological conditions in winter and spring had the biggest impact on the abundance level of insects of the midges complex. Fluctuations in the abundance were 9 times for mosquitoes, 20 times for tabanid flies, and 39 times for midges and sandflies depending on the season. The main limiting factors for mass development of blood-sucking Diptera in the forest-steppe zone of the Tyumen Region are hard and dry winters which cause death of some insects at the preimaginal stages in development, as well as sharp changes in air temperature in the spring-summer period and small areas of breeding places.

Hydrological regime and runoff formation of the Chulym river and its analysis

One of the main problems of hydrology is the formation of rainfall floods and the assessment of the hydrological regime of rivers. Analysis of the factors of river runoff formation helps to calculate the main hydrological characteristics even in the river sections not illuminated by field data. One of the regional methods for calculating hydrological characteristics is the calculation of the dependences of runoff characteristics on the physical and geographical factors of the catchment area. Such calculations are based on the results of generalizing the data of hydrometeorological observations in the design area. There is often a need for runoff characteristics in the design section of the river where there are no field data of hydrometric observations, and this problem is considered in the proposed study. This is the first time this approach has been implemented for the Chulym River. This article examines the analysis of the factors of the river runoff of the Chulym river, which makes it possible to make objective calculations of the main hydrological characteristics in the sections of the rivers not illuminated by field observations.

Monitoring of destruction and shallowing of water bodies and bank protection structures in the Volga river delta within the framework of the "Ecology of safe construction" program

Objective. The article describes the features of works on coastal protection of territories subject to slope processes. The role of research of leading processes of destruction of coastal zones in the framework of the program “The Ecology of Safe Construction and Municipal Services” for forecasting and preventing risks, as well as providing information for further work on building reliable coastal protection, is emphasized. Despite the existing variety of ways to protect embankments from erosion, the search for new technical solutions at the moment continues to be an urgent task.Methods. Geotechnical monitoring of hydraulic structures was carried out. Visual assessments of cracks, slopes of individual structural blocks, and deformations were performed. A thermal imager device is used to search for abnormal temperatures and an electronic hardness meter that measures the strength of concrete.Results. It is determined that the water regime of the Astrakhan Region is characterized by an uneven distribution of runoff due to a direct dependence on the flow rate from the Volgograd hydropower plant. The predominant source of moisture is discharges in the form of a series of rain floods, which often cause flooding. One of the most effective solutions is to preserve the operational characteristics of the bank protection spur-pile of variable cross-section when changing the hydrological river regime. The bank protection spur runs partially movable horizontally and vertically and comprises a head spur in the form of piles of variable height; the body in the form of a floating garland of variable cross-section; the base in the form of a slider block. The design and technological solution allow blocking the coastal stream with the body of the spur at any water level and changing the angle of inclination of the spur with the protected shore.Conclusion. Prevention of emergencies, especially in urbanized areas that are subject to intense anthropogenic impact, is possible only when engineering protective structures are built, which have a positive effect both in protective and environmental aspects.

Трансформация стока весеннего половодья и паводков в бассейне Верхней Волги под влиянием климатических изменений

An increase in the average annual air temperature in the European territory of Russia against the background of climate change leads to a decrease in water reserves in the flood-forming snow cover. At the same time, an increase in the number of transitions of air temperature through 0 ° С in the area of positive values in winter leads not only to an additional reduction in snow storage by the beginning, but also ensures an increase in the number and size of thaw floods. Changes in the intra-annual distribution of the range and intensity of precipitation entail an increase in the number and magnitude of rainfall floods. Observed transformations in the types of feeding and water regime of the rivers of the basin. Methods. The study posed the task of studying climate change on the hydrological regime of rivers in the Upper Volga basin. To solve it, methods were used to determine the methods for determining the runoff components based on the dismemberment of the hydrograph using the GrWat software package and mapping the results of the results. As part of this task, more than two thousand hydrographs were analyzed, and their long-term trends were analyzed. Results. The analysis showed that on some rivers of the region the volume of flood runoff is already comparable to the volume of flood runoff, which is not typical for the river-European type of water regime. It was found that for some rivers in the region, the volume of runoff during high water decreased by more than 50%, while the volume of runoff during the period of rainfall floods increased by more than 80%,while in the period of thaw practically by 100%.

Hydro-modifications matter: Influence of vale transformation on microinvertebrate communities (Rotifera, Cladocera, and Copepoda) of upland rivers

Anthropogenic transformations of the catchment area and river bed are responsible for the changes in the geomorphology of the river valleys, the hydrological regime of rivers, the river continuum, as well as the river ecosystems. Transformed valleys offer ecological niches that are different from the natural ones, which are inhabited by organisms that should not be present in a high density in rivers or streams. We aimed to answer the question of whether the communities of microinvertebrates are indicative of anthropogenic transformations taking place in the river bed and in the catchment area. For this purpose, the study was conducted on the six upland rivers in the drainage of the Douro River, Northern Portugal. According to our results, for the diversity and abundance of microinvertebrate communities (Rotifera, Cladocera, and Copepoda), the characteristics of the catchment area are not as important as the transformation of the riverbed. The abundance of microinvertebrates is related to natural processes that are described in the river continuum concept; however, dams higher than 10 m drastically reorganized communities from benthic to typically pelagic. Large dams (>10 m) built on small rivers caused an apparent increase in species richness, as these species are the same as those found in large rivers. Therefore, the river networks were homogenized both in relation to microinvertebrate abundance and taxa. Less transformation of the riverbed (lack of impoundments) favors the greater Simpson diversity of microinvertebrates, but the density is then very low. Our results show that dams have a large influence on the communities of microinvertebrates in the river, which in turn can cause cascading spatial changes to the river ecosystem.

Azov–Don Water Problem

The article considers the set of water management problems that has formed in the Don Basin in the context of current changes in the hydrological regime of rivers and an increase in the demand for the reliability of water resources available for economic sectors. Despite the decline in production and water consumption, the ecological conditions of water bodies in the basin have not improved, many problems have become more acute, the overall environmental situation has deteriorated, and fish production in the Sea of Azov has decreased. Hydrochemical observations in the Don Basin demonstrate deterioration of water quality. Measures proposed to improve water management situation are discussed. It is shown that the forecasts of water use and changes in water environment made in the 1970s have not proved true. The ways to solving the problem of water supply in the Azov–Don Basin are considered.

Stage-dependent effects of river flow and temperature regimes on the growth dynamics of an apex predator.

In the world's rivers, alteration of flow is a major driver of biodiversity decline. Global warming is now affecting the thermal and hydrological regimes of rivers, compounding the threat and complicating conservation planning. To inform management under a non-stationary climate, we must improve our understanding of how flow and thermal regimes interact to affect the population dynamics of riverine biota. We used long-term growth biochronologies, spanning 34years and 400,000km2 , to model the growth dynamics of a long-lived, apex predator (Murray cod) as a function of factors extrinsic (river discharge; air temperature; sub-catchment) and intrinsic (age; individual) to the population. Annual growth of Murray cod showed significant, curvilinear, life-stage-specific responses to an interaction between annual discharge and temperature. Growth of early juveniles (age 1+ and 2+ years) exhibited a unimodal relationship with annual discharge, peaking near median annual discharge. Growth of late juveniles (3+ to 5+) and adults (>5+) increased with annual discharge, with the rate of increase being particularly high in adults, whose growth peaked during years with flooding. Years with very low annual discharge, as experienced during drought and under high abstraction, suppress growth rates of all Murray cod life-stages. Unimodal relationships between growth and annual temperature were evident across all life stages. Contrary to expectations of the Temperature Size Rule, the annual air temperature at which maximum growth occurred increased with age. The stage-specific response of Murray cod to annual discharge indicates that no single magnitude of annual discharge is optimal for cod populations, adding further weight to the case for maintaining and/or restoring flow variability in riverine ecosystems. With respect to climate change impacts, on balance our results indicate that the primary mechanism by which climate change threatens Murray cod growth is through alteration of river flows, not through warming annual mean temperatures per se.

Susceptibility of Water Resources and Hydropower Production to Climate Change in the Tropics: The Case of Lake Malawi and Shire River Basins, SE Africa

The sensitivity of key hydrologic variables and hydropower generation to climate change in the Lake Malawi and Shire River basins is assessed. The study adapts the mesoscale Hydrological Model (mHM) which is applied separately in the Upper Lake Malawi and Shire River basins. A particular Lake Malawi model, which focuses on reservoir routing and lake water balance, has been developed and is interlinked between the two basins. Climate change projections from 20 Coordinated Regional Climate Downscaling Experiment (CORDEX) models for Africa based on two scenarios (RCP4.5 and RCP8.5) for the periods 2021–2050 and 2071–2100 are used. An annual temperature increase of 1 °C decreases mean lake level and outflow by 0.3 m and 17%, respectively, signifying the importance of intensified evaporation for Lake Malawi’s water budget. Meanwhile, a +5% (−5%) deviation in annual rainfall changes mean lake level by +0.7 m (−0.6 m). The combined effects of temperature increase and rainfall decrease result in significantly lower flows in the Shire River. The hydrological river regime may change from perennial to seasonal with the combination of annual temperature increase and precipitation decrease beyond 1.5 °C (3.5 °C) and −20% (−15%). The study further projects a reduction in annual hydropower production between 1% (RCP8.5) and 2.5% (RCP4.5) during 2021–2050 and between 5% (RCP4.5) and 24% (RCP8.5) during 2071–2100. The results show that it is of great importance that a further development of hydro energy on the Shire River should take into account the effects of climate change, e.g., longer low flow periods and/or higher discharge fluctuations, and thus uncertainty in the amount of electricity produced.

Editorial: Implementing Environmental Flows: Lessons for Policy and Practice

Water resources and freshwater ecosystems are under pressure from a growing human population, thirstier lifestyles, and climate change (UNESCO and UN water, 2020). Consequently, water-related risks to society are increasing (World Economic Forum, 2020) and freshwater biodiversity is rapidly declining (Grooten, 2018). The UN Sustainable Development Goals (SDGs) include targets for improved water management, including SDG 6.4, which stipulates sustainable water withdrawals, and SDG 6.6, aimed at halting the degradation of water-related ecosystems. The hydrological regimes of rivers and other wetlands can be regarded as a litmus test of whether these targets are met (Tickner and Acreman, 2013). Environmental flow assessment (EFA) is the science-based process of determining appropriate flow regimes for individual water bodies given environmental, socio-economic and cultural objectives. Researchers have developed sophisticated EFA tools (Acreman et al., 2014; Poff et al., 2017) but implementation of environmental flows has been problematic, and research into the challenges of implementation is scarce.

Modern Changes in Hydrological Regime and Water Supply in the Moscow Region

The changes in the hydrological regime of rivers in the Moscow region occurred under global warming. It is expressed in the redistribution of runoff within a year: an increase in minimum runoff and a decrease in flood runoff. The analysis of the series of the inflow to the Moskvoretskaya system reservoirs revealed stationarity disturbances in the studied series for the period of 1978–1980. This was followed by a change in the characteristics of runoff regulation carried out for water supply in the Moscow region. It is shown that the inflow changes led to the statistical heterogeneity of the series of regulation characteristics, including the total live storage and water deficiency. The Bayesian method is proposed for obtaining statistical characteristics of nonstationary series of the inflow and yield of the Moskvoretskaya system reservoirs.

Research progress and ideas of Influence of hydrological regimes on river primary productivity of algae

The algae, as the primary producer of the water ecosystem, are the basic part of food chain in aquatic ecosystem. The flow pattern and hydrological process of the river have been significantly changed by the construction of the high dams. Not only the natural hydrological characteristics and physical and chemical conditions of the river were changed by the obstacle of the dams, but also the habitat environment on which the phytoplankton live, and its community structure, biomass and primary productivity of the water further were affected. In this paper, the research on the effect of river hydrological regime change on the primary productivity of water body were summarized and summarized. In the future, further research can be carried out in these aspects: (i) the analysis of the key factors affecting the primary productivity; (ii) clarifying the mechanism of the influence of hydrological situation change on the primary productivity and its distribution of algae in the reservoir area and downstream channel; (iii) establishing the coupling relationship between the change of hydrological regime and the primary productivity of phytoplankton.

Evaluation of river hydrological regime changes under the influence of Gangkouwan Reservoir

The construction of the reservoir has met human needs to a certain extent, but it has caused serious threats to river ecosystems, especially for the hydrological regime. In order to deepen the understanding of the impact of the reservoir, this paper introduces the Indicators of Hydrologic Alteration (IHA) method, constructs an indicator system that describes the changes in hydrological regime, and uses the Range of Variability Approach (RVA) to quantitatively evaluate the changes of 5 groups of 33 indexes after the construction of Gangkouwan Reservoir, thus realizing the quantitative change of the river hydrological regime. The results show that the Gangkouwan Reservoir affects the frequency and duration of high and low pulses highly, as well as in rate and frequency of water condition changes, and the integral change degree of hydrological regime is moderate.