Influence Of Hydrological Regime Research Articles

Carbon leaching from peat soils of the north of Western Siberia under different hydrological conditions

Frozen peat soils in the north of Western Siberia are vulnerable to the on-going climate changes. The increase in temperature which affects the permafrost thaw returns the huge carbon stocks to the global element cycle. Its export in the form of dissolved organic matter from peatlands is determined by a number of factors, among which hydrological conditions are the least studied. The influence of hydrological regimes on carbon export from oligotrophic peat soils in discontinuous permafrost zone was investigated in laboratory conditions. The model column experiment allowed estimating the carbon yield from undisturbed (monolithic) peat samples of different degrees of decomposition. Three types of mesocosms were considered: undisturbed samples of the TO horizon, as well as the TO horizon with underlying material of different texture (sand and loam). The concentration of dissolved organic carbon in the lysimetric waters of a fibric peat does not differ for the “precipitation” and “snowmelt” simulating modes, and in the “stagnation” mode it is 1.4 times less. Sapric peat lysimetric waters show no differences under simulating hydrological regimes. The total export of organic carbon for three successive extractions for fibric peat is 32% higher than for sapric peat. An increase in carbon in the sandy material after three cycles of the experiment was revealed, the loamy material did not show significant differences. The carbon adsorption by mineral soil layers of the study area can be a protective mechanism that prevents increased runoff from the soils.

Influence of hydrological regimes on the ecological balance of the environment: case study of the Republic of Ingushetia

Dragonflies are amphibious insects whose existence is associated with water bodies that are necessary for the development of larvae. Different types of dragonflies differ in the requirements for the choice of habitats. In mountain species, preferences depend on the height of the habitat. The analysis of the existing flow of literary information on dragonflies indicates that there are still problems that require close attention. First and foremost, this is insufficient study of Caucasian regional odonata faunas. Of all the unique Caucasian regions, the territories of the Dagestan and Chechen Republics were the least studied with regard to dragonflies. This is caused by the acute shortage of specialists and the difficulties of studying the group of animals of this original and unique region, which is located at the biogeographic crossroads of various faunas. Siberian, European, Mediterranean, Ethiopian, Central and East Asian dragonfly species fly together within these territories. A significant number of scientific articles are devoted to Caucasian dragonflies, testifying to the unique fauna of dragonflies in the region. At the same time, there are many unresolved issues of the taxonomic nature of some dragonfly species, their propagation, distribution over high-altitude zones, life cycles of ontogenesis, and some environmental issues, in particular, the phenology of the group in the peculiar and unique physical, geographical and landscape conditions of the Republic of Ingushetia. There is a relatively extensive literature on the dragonflies of the Caucasus, while there is no purposeful summary of the ecological-faunal, ecological-geographical and zoogeographic features of this group of insects in the Republic of Ingushetia. Another problem that has not yet been solved is the establishment of patterns of dragonfly propagation along the altitude gradient, as well as the peculiarities of the formation of odonatocomplexes in various high-altitude zones of the Republic of Ingushetia.

Influence of hydrological regime on spatiotemporal distribution of boron in sediments in the Three Gorges Reservoir, China

Hydropower dam construction can alter the continuity of the river flow, thereby influencing geochemical cycle of seldom monitored trace elements due to the change of hydrological regime by reservoir regulation. Here, we investigated the response of hydrological regime on migration of boron (B) in the sediments of Three Gorges Reservoir (TGR) using multiple geochemical approaches. Although B concentrations in TGR sediments increased slightly during five consecutive water seasons, the potential ecological risk exhibited relatively low. The spatial distribution patterns of B with high heterogeneity in TGR sediments were influenced by periodic water-level fluctuation. This high spatial heterogeneity significantly correlated with the distribution of fine-grain sediments, which was attributed to the change of hydrological regime (including the decrease of water flow velocity, sediment accumulation, and extended residence time of suspended fine-grain sediments). In order to remove the sediment size effect, the geochemical normalization approach was applied, and revealed that the slope of normalization curve remarkably decreased from 0.9402 to 0.3682. This indicated that a small amount of B was still accumulated in the mid- and downstream of TGR after removing the hydrological regime effect. Further source identification using geochemical baseline model and principal component analysis, exposed that this slight accumulation of B in sediments originated from the anthropogenic input (8.45%). Our findings provide a geochemical insight on the environmental impacts of reservoir operation on toxic element cycling, with potential implications for ecological assessment of hydropower worldwide.

Soil hydrology drives ecological niche differentiation in a native prairie microbiome.

While the impacts of soil moisture on soil microbiome diversity and composition are well characterized, the influence of hydrological regime has been overlooked. As precipitation patterns are altered by climate change, understanding the impact of soil hydrology on community structure and function is critical. In this work, water level was continuously monitored for over a year in a Midwestern prairie-wetland at 10 cm depth increments up to a depth of 120 cm in 10 locations. We analyzed microbiome composition and edaphic factors in soil cores collected from this unique spatially distributed, longitudinal data set. We demonstrate that the fraction of time that each sample was inundated explains more variability in diversity and composition across this site than other commonly assessed edaphic factors, such as soil pH or depth. Finally, we show that these compositional changes influence abundance of ammonia oxidizers. The observed patterns in community composition and diversity are fundamentally regulated by the interaction of water with a structured landscape, particularly an elevated sand ridge characterized by drier conditions and a lower-lying wetland with more clayey soils. Similar processes are generally expected to influence the biogeography of many terrestrial environments, as morphology, hydrology and soil properties generally co-vary.

Influence of hydraulic retention time and amplitude of water level fluctuations on water quality in irrigation reservoirs of the Kala Oya river basin, Sri Lanka

Management of reservoir water quality is a global challenge due to the natural process of eutrophication and anthropogenic aggravation. In Sri Lanka, irrigation reservoirs support several secondary uses such as fish production, livestock farming, and many communal uses including drinking water supply. In the present study, basic limnological parameters of ten irrigation reservoirs of Sri Lanka were investigated from June 2013 to February 2016, with a view to identifying influence of hydrological regimes on reservoir water quality. Spatio-temporal similarities of water quality parameters were studied employing the self-organizing map (SOM) routine of the artificial neural network application. The sample vectors, classified on the SOM lattice, indicated 6 clusters at 50% similarity level. When reservoir that were categorized according to hydraulic retention time (HRT) and relative reservoir level fluctuation (RRWL; defined as the ratio of the mean reservoir level amplitude to mean depth), were compared with dominant water quality parameters in SOM lattice, it was evident that some productivity-related water quality parameters were influenced HRT and RRWL. The results of the study revealed that HRT and RRWL can essentially be controlled through management of hydrological regimes in irrigation reservoirs, thus, close dialogue between irrigation authorities and other users of reservoir water resources are needed to ensure desired water quality of the reservoirs.

Influence of hydrological regime and climatic factor on waterbird abundance in Dongting Lake Wetland, China: Implications for biological conservation

Understanding how migratory waterbirds respond to hydrology and climate is of great importance for providing valuable insight into conservation in wetland system. Dongting Lake Wetland is an important wintering habitat in the East Asian-Australasian Flyway. However, little is known about the effects of hydrology and climate on wintering waterbirds. Therefore, it is urgent to analyze the relationship between them. To better interpret the ecological significance, we divided the bird species into five functional groups on the basis of their typical feeding habits. Redundancy analysis (RDA) combined with forward selection procedure was applied to select the hydrological and climatic variables with significant influences. Then, response surface methodology (RSM) was carried out to identify the thresholds of the variables. The results showed that inflow and water level were probably the two critical variables accounting for 52.13% and 47.87% of the variation in the bird species, respectively. However, other variables did not reach a significant level in this study. As for the group-level, different functional bird groups had different reflections to inflow and water level. Minimal guaranteed values of the two variables were identified as 3518.82–3736.28m3/s and 22.61–23.49m respectively based on the hydrological requirements and the weights of all groups. The results highlighted that the minimal requirements of inflow and water level should be satisfied to provide appropriate habitats for waterbirds. Besides, the regulatory authorities and environmental protection agencies should develop relevant law or regulation to protect waterbird habitats from human destruction especially the activities which could change the hydrological regime.

Influence of hydrological regime and land cover on traits and potential export capacity of adult aquatic insects from river channels.

Despite many studies highlighting the widespread occurrence and effects of resource movement between ecosystems, comparatively little is known about how anthropogenic alterations to ecosystems affect the strength, direction and importance of such fluxes. Hydrological regime and riparian land use cause well-documented changes in riverine larval invertebrate communities. Using a dataset from 66 sites collected over 20 years, we showed that such effects led to spatial and temporal differences in the density and type of larvae with winged adults within a river reach, altering the size and composition of the source pool from which adult aquatic insects can emerge. Mean annual larval densities varied 33-fold and the temporal range varied more than 20-fold between sites, associated with the hydrological regime and land cover and antecedent high and low flows, respectively. Densities of larvae with winged adults were greater in sites that had more algal coverage, agricultural land use, seasonally predictable flow regimes and faster water velocities. More interestingly, by influencing larval communities, riparian land use and the magnitude and frequency of high and low flows affected the size structure, dispersal ability and longevity of adults available to emerge from river reaches, potentially influencing the spatial extent and type of terrestrial consumers supported by aquatic prey. This suggests that anthropogenic alterations to land use or river flows will have both spatial and temporal effects on the flux and potential availability of adult aquatic insects to terrestrial consumers in many rivers.

Influence of Hydrological Regime in Determining the Response of Macroalgal Blooms to Nutrient Loading in Two Irish Estuaries

Eutrophication and the development of persistent opportunistic macroalgal blooms are recognised as one of the main detrimental effects of increased anthropogenic pressures on estuarine and coastal systems. This study aimed to highlight the interplay between pressures and controlling physical factors on ecosystem functioning. The hypothesis that hydrological regime can control the growth of opportunistic macroalgae was tested with the study of two Irish estuaries, the Argideen and the Blackwater, with similar nutrient loading sources but divergent hydrological regimes. Seasonal monitoring data was initially examination, while the application of a pre-existing box model allowed a further analysis of the influence of residence time and nutrient load modifications on macroalgal growth. Seasonal oscillations in monitored river flow rates altered nutrient transfer from the catchments to the estuaries in both cases, as is shown through differences between winter and summer nutrient concentrations. In the Argideen, however, the relative contribution of phosphorus (P) from adjacent marine waters was high due to the shorter residence times and greater influx of marine water into the estuary. Modelling studies showed that in the Argideen Estuary, P load reduction would have potentially minimal impact on macroalgal growth due to the shorter residence time which increased the influx of P from marine sources. Nitrogen (N) load reduction of 60 % had a significant, albeit limited, impact on macroalgae and was insufficient in achieving the environmental objectives for this waterbody. For the more river-dominated Blackwater Estuary, modelled reductions in P resulted in a considerable decrease in biomass. Any further P decreases would accentuate the existing disparity in estuarine N:P ratios with possible repercussions for N transport to the coastal system. Hence, the hydrological complexity of estuarine systems demonstrated dictates that a portfolio of separate, but complimentary, management approaches may be required to address eutrophication in these estuaries.

Long-term impact of hydrological regime on structure and functions of microbial communities in riverine wetland sediments

In a context of global change, alterations in the water cycle may impact the structure and function of terrestrial and aquatic ecosystems. Wetlands are particularly at risk because hydrological regime has a major influence on microbially mediated biogeochemical processes in sediments. While the influence of water availability on wetland biogeochemical processes has been comprehensively studied, the influence of hydrological regime on microbial community structure has been overlooked. We tested for the effect of hydrological regime on the structure and functions of microbial communities by comparing sediments collected at multiple sites in the Ain département (Eastern France). Each site consisted of two plots, one permanently and one seasonally inundated. At the time of sampling, all plots were continuously inundated for more than 6 months but still harboured distinct bacterial communities. This change in community structure was not associated with marked modifications in the rates of microbial activities involved in the C and N cycles. These results suggest that the observed structural change could be related to bacterial taxa responding to the environmental variations associated with different hydrological regimes, but not strongly associated with the biogeochemical processes monitored here.

Influence of hydrological regime on wetland attenuation of diffuse agricultural nitrate losses

A simple first-order dynamic model that accounts for hydrology, nitrate concentrations, internal hydraulic efficiency and water temperature was used to evaluate the influence of influent hydrological regimes on nitrate-N removal performance in surface-flow wetlands. The model, run using hourly hydrological and climatic data for a wetland treating subsurface tile drainage, was able to closely simulate flow-proportional nitrate-N concentrations recorded at the wetland outlet. Applying the model to 7 different annual flow regimes showed substantial year-to-year differences in predicted percentage and mass nitrate-N removal performance. Predicted areal mass removal rates declined markedly as wetland size was increased from 0.5 to 5% of contributing catchment, illustrating the diminishing returns achievable and the performance limits of wetland treatment receiving highly variable diffuse flows. Doubling the wetland size from 1% to 2% of contributing catchment provided about 75% increase in performance, but doubling from 2% to 4% of catchment area only provided about 43% further improvement. Large wetland areas occupying 5% of contributing catchment were predicted on average to be able to remove a maximum of 55% of the nitrate-N loads delivered, with removal expected to range between 40 and 70% of the nitrate-N load from year-to-year depending primarily on the flow regime. Application of the model to equivalent wetlands receiving normalised stream flows (same nitrate-N concentration, total flow and load) from up- and down-stream sites in two catchments with contrasting flow regimes predicted substantially better overall performance when flows were steady or exhibited low variability. With increasing flow variability predicted wetland nitrate-N removal efficiency was reduced by 5–14 and 13–21 percentage points for wetlands occupying 1 and 4% of catchment area, respectively. We conclude that flow regime is likely to be a key factor influencing the nitrate-N removal performance of surface-flow wetlands receiving diffuse flows from agricultural catchments. Seasonal patterns and variability of flow need to be seriously considered when assessing expected performance, and in optimising the location and design of wetlands for diffuse pollution management.

The influence of hydrological regimes on sex ratios and spatial segregation of the sexes in two dioecious riparian shrub species in northern Sweden

River management practices have altered the hydrological regimes of many rivers and also altered the availability of regeneration niches for riparian species. We investigated the impact of changed hydrological regimes on the sex ratios and the Spatial Segregation of the Sexes (SSS) in the dioecious species Salix myrsinifolia Salisb.–phylicifolia L. and S. lapponum L. by studying the free-flowing Vindel River and the regulated Ume River in northern Sweden. We surveyed sex ratios of these species in 12 river reaches on the Vindel River and in 17 reaches on the Ume River. In addition, we surveyed the sex and location above mean river stage of 1,002 individuals across both river systems to investigate the SSS of both species. Cuttings were collected from male and female individuals of S. myrsinifolia–phylicifolia from both rivers and subjected to four different water table regimes in a greenhouse experiment to investigate growth response between the sexes. We found an M/F sex ratio in both river systems similar to the regional norm of 0.62 for S. myrsinifolia–phylicifolia and of 0.42 for S. lapponum. We found no evidence of SSS in either the free-flowing Vindel River or the regulated Ume River. In the greenhouse experiment, hydrological regime had a significant effect on shoot and root dry weight and on root length. Significantly higher shoot dry weights were found in females than in males and significantly different shoot and root dry weights were found between cuttings taken from the two rivers. We concluded that changed hydrological regimes are likely to alter dimensions of the regeneration niche and therefore to influence sex ratios and SSS at an early successional stage, making it difficult to find clear spatial patterns once these species reach maturity and can be sexed.

Influence of hydrological regimes on the pre‐spawning entry of Atlantic salmon (Salmo salar L.) into an upland river

AbstractThe Girnock Burn is an Atlantic salmon (Salmo salar) spawning tributary of the river Dee, Aberdeenshire, Scotland. The dates, sexes and numbers of adult salmon entering the stream in the three months prior to spawning were determined between 1969 and 2005 using a permanent fish‐trap. During this time, the number of fish returning to spawn varied markedly. Here we analyze the whole of this unique long term data set in order to characterize and classify the hydrologic regimes of the pre‐spawning migration period and assess the extent to which these regimes help explain the timing and patterns of arrival of adult salmon into the stream. A range of flow parameters was calculated for the arrival period (September–November) for each of the 37 years. These parameters were used to ordinate and classify years according to their flow regimes. The analysis yielded six distinct groups or ‘flow regime types’ which separated principally in relation to flow magnitude and frequency parameters. The number of fish entering the burn on a given day was not significantly correlated to discharge on that day. However, patterns of arrival of fish differed markedly between years with different regime types, with the number of fish arriving on a given day related to patterns of discharge over the preceding part of the arrival period. Overall inter‐annual variability in entry corresponded to the defined regime types. In wetter years, fish entry to the stream usually starts relatively early and continues throughout the pre‐spawning period. In contrast, dry years may result in fish entry being delayed; this may result in lower numbers of spawning females entering the stream and sub‐optimal utilization of juvenile habitat in the following spring. Copyright © 2008 John Wiley & Sons, Ltd.

The influence of hydrological regime and grazing management on the plant communities of a karst wetland (Skealoghan turlough) in Ireland

AbstractQuestion: What is the influence of hydrological regime, soils and management on the plant community composition and species richness of Skealoghan turlough (groundwater dependent calcareous wetland).Location: Skealoghan turlough, County Mayo, Ireland.Methods: Percentage cover of vascular plants and bryophytes were recorded, and data on hydrological regimes, soils and management were collected. Data were analysed using multivariate statistical techniques.Results: A total of 69 species of vascular plants and mosses were recorded. Cluster analysis grouped the samples into two separate communities, the Cirsio‐Molinietum and the Ranunculo‐Potentilletum anserinae plant communities. The plant community composition and species richness followed a main gradient down into the turlough basin, but also varied with microtopography, resulting in a mosaic of vegetation types.Conclusions: The biodiversity and conservation value of the site is linked to the heterogeneity in its physical environment in which hydrology, soils and grazing management all play critical roles.

Exotic invasive black willow (Salix nigra) in Australia: influence of hydrological regimes on population dynamics

Floodplain vegetation occupies disturbance prone habitats vulnerable to exotic plant invasion. Black willow (Salix nigra Marshall) is a flood-tolerant tree native to the southeastern United States and recently invasive in Australia, where it is considered detrimental to riparian environments. Effective management of S. nigra requires understanding the impacts of hydrological conditions on population dynamics at each stage of the plant’s life cycle. The influence of inundation events (timing, duration, and recession rates) on S. nigra stand dynamics and relative growth rate (RGR) was quantified across a hydrological gradient on the shorelines of Blowering Dam reservoir (NSW, Australia). Successful recruitment (sexual and asexual) and establishment is highly dependent on the position of S. nigra recruits above reservoir water levels and exposure to flooding during the first few years of establishment. Recruitment was ubiquitous along the hydrological gradient but a greater number of asexual recruits were found at higher elevations where inundation events are less frequent. Juvenile mortality was highest at lower elevations, which experienced greater depth and duration of inundation. Mean RGR was greatest in S. nigra stands experiencing no inundation over the study period and declined as inundation duration increased. Flooding events inhibit adult growth, but create suitable conditions for seedling recruits, provided the depth and duration of the flood does not exceed complete submersion for more than 30 days. To investigate relative tolerance to water table decline rooted S. nigra cuttings were grown in rhizopods, controlled growth devices that allow water-table manipulation. Water-table decline rates of 0, 1, 2, 4, and 8 cm day−1 were applied and the response of leaf abscission measured. S. nigra cuttings were not significantly impacted at water-table decline rates of between 1 and 4 cm day−1. Spatial location of S. nigra recruits in Australian floodplains represents a trade-off among hydrological conditions that promote recruitment without inducing mortality, resulting in a narrow spatial and temporal regeneration window critical to successful establishment. Future distribution and abundance of S. nigra in Australia will be determined by propagule availability and the degree to which current and future flow regimes create suitable hydrological conditions for successful establishment.

The influence of hydrological regime and grazing management on the plant communities of a karst wetland (Skealoghan turlough) in Ireland

The influence of hydrological regime and grazing management on the plant communities of a karst wetland (Skealoghan turlough) in Ireland

Influence of hydrological regime on carbon dioxide fluxes over oligotrophic bog massif in northwestern Russia

It is found that the surface bog temperature and bog water level position are major factors that determine CO2 emission from the bog massif. The emission intensity increases with increasing temperature and with a bog water level decrease. The dependence of CO2 emission is shown to be different for each bog microlandscape. Monthly mean CO2 emissions are given for the central bog massif in the years with different water content. Based on modeling, it is shown that in the case of a low bog water level the CO2 flux is directed to the atmosphere (the emission value exceeds the gas amount consumed for photosynthesis), while in the case of a high level, it is taken up by the growing plants.

Influence of hydrological regime on pore water metal concentrations in a contaminated sediment-derived soil

Options for wetland creation or restoration might be limited because of the presence of contaminants in the soil. The influence of hydrological management on the pore water concentrations of Cd, Cr, Cu, Fe, Mn, Ni and Zn in the upper soil layer of a contaminated overbank sedimentation zone was investigated in a greenhouse experiment. Flooding conditions led to increased Fe, Mn, Ni and Cr concentrations and decreased Cd, Cu and Zn concentrations in the pore water of the upper soil layer. Keeping the soil at field capacity resulted in a low pore water concentration of Fe, Mn and Ni while the Cd, Cu, Cr and Zn concentrations increased. Alternating hydrological conditions caused metal concentrations in the pore water to fluctuate. Formation and re-oxidation of small amounts of sulphides appeared dominant in determining the mobility of Cd, Cu, and to a lesser extent Zn, while Ni behaviour was consistent with Fe/Mn oxidation and reduction. These effects were strongly dependent on the duration of the flooded periods. The shorter the flooded periods, the better the metal concentrations could be linked to the mobility of Ca in the pore water, which is attributed to a fluctuating CO 2 pressure.

Ecological studies on the Kerkini reservoir (N Greece)

The influence of hydrological regime of the artificial lake Kerkini (N Greece) on the qualitative and quantitative distribution of plankton populations, was studied during a 12 months period.Cyanophyceae, chlorophyceae, dinophyceae, diatomeae, crysophyceae andcryptophyceae, in considerable seasonal variation in their abundance, diversity and number comprised the phytoplankton population. The abundance of rotifers and the presence of various copepod stages throughout the year were also characteristic. Lake Kerkini should be considered as eutrophic with a tendecy to become hypertrophic. River inflows affect greatly in reservoir's water volume, nutrients' concentration and water's transparency, which, consequently, affects the plankton growth.