Seasonal Water Level Fluctuations Research Articles

Long-term and seasonal water level fluctuations of the Rybinsk Reservoir and their role in the functioning of its ecosystem

Seasonal and long-term variability of the Rybinsk Reservoir level regime over the period of its operation was analyzed. Changes in the level regime at different phases of water content were shown together with the data on mean monthly and extreme level values and the rates of the reservoir filling and drawdown. The level regime impact on the functioning of individual components of the reservoir ecosystem was discussed. Due consideration was given to the assessment of changes in the reservoir environmental situation under the condition of the normal impounded water level drop by 1 m.

Establishing a Rural Groundwater Monitoring Network Using Existing Wells: West Nose Creek Pilot Study, Alberta

Sustainable groundwater management requires long-term monitoring of aquifer water level, water quality, and water use with adequate spatial and temporal resolution in order to evaluate the response of the aquifer to changes in pumping rates and meteorological conditions. Since existing federal and provincial monitoring programs do not have sufficient spatial resolution, an alternative is to establish locally-based monitoring programs coordinated by municipalities or watershed groups. A network of more than 20 monitoring wells was implemented in the West Nose Creek watershed near Calgary, Alberta using existing water supply wells. The network effectively captured the pattern of seasonal and inter-annual fluctuations of aquifer water level. Understanding of the natural fluctuation will help the community detect any undesirable effects of increasing water extraction in the future. Biannual newsletters were distributed to the well owners and a wider community within the watershed to communicate the results and background knowledge. The methodology established in this pilot study may provide a cost-effective tool for rural groundwater monitoring in the Canadian prairies and elsewhere.

Managing vegetation in surface-flow wastewater-treatment wetlands for optimal treatment performance

Constructed wetlands that mimic natural marshes have been used as low-cost alternatives to conventional secondary or tertiary wastewater treatment in the U.S. for at least 30 years. However, the general level of understanding of internal treatment processes and their relation to vegetation and habitat quality has not grown in proportion to the popularity of these systems. We have studied internal processes in surface-flow constructed wastewater-treatment wetlands throughout the southwestern U.S. since 1990. At any given time, the water quality, hydraulics, water temperature, soil chemistry, available oxygen, microbial communities, macroinvertebrates, and vegetation each greatly affect the treatment capabilities of the wetland. Inside the wetland, each of these components plays a functional role and the treatment outcome depends upon how the various components interact. Vegetation plays a uniquely important role in water treatment due to the large number of functions it supports, particularly with regard to nitrogen transformations. However, it has been our experience that vegetation management is critical for achieving and sustaining optimal treatment function. Effective water treatment function and good wildlife quality within a surface-flow constructed wetland depend upon the health and sustainability of the vegetation. We suggest that an effective tool to manage and sustain healthy vegetation is the use of hummocks, which are shallow emergent plant beds within the wetland, positioned perpendicular to the water flow path and surrounded by water sufficiently deep to limit further emergent vegetation expansion. In this paper, we describe the use of a hummock configuration, in conjunction with seasonal water level fluctuations, to manage the vegetation and maintain the treatment function of wastewater-treatment wetlands on a sustainable basis.

Nutrient chemistry of groundwater in an intensively irrigated region of southern India

The concentration of nutrients in groundwater acts as an indicator to identify the influence of agricultural activities on the shallow subsurface environment. Hence, the present study was carried out to assess nutrient concentration (nitrate, phosphate and potassium) and understand its spatial and seasonal variations in the groundwater of Palar and Cheyyar River basin, Tamil Nadu, India. The groundwater samples collected from 43 wells were analyzed for nutrients once a month from January 1998 to June 1999. Results of the study suggested that agricultural activities, including application of fertilizers, soil mineralization processes and irrigation return flow, are major processes regulating the nutrients chemistry in the groundwater of this region. Groundwater in the sedimentary formation has comparatively higher concentration of nutrients than the groundwater in hard rock formations, which seems to be due to the adsorption of nutrients by the weathered rock materials. The seasonal water level fluctuation shows that rising water level increases nutrients concentration in groundwater due to the agriculture related activities. The results also indicate that nitrate and potassium concentrations are within the recommended drinking water limits, whereas phosphate concentration exceeds its drinking water limit and 35% of the samples are unsuitable for drinking purposes.

Seasonal water level fluctuations: Implications for reservoir limnology and management

AbstractWith the purpose of finding out whether seasonal water level fluctuations could affect water quality in a reservoir subjected to those changes, trends in environmental variables and in phytoplankton and zooplankton assemblages were analysed. The reservoir's hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid‐June to the beginning of September and the minimum level phase lasted from mid‐September to the beginning of the first autumn/winter rain events. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, water colour and chlorophyll a were found during the minimum level phase. The phytoplankton assemblage was dominated by taxa typical of meso‐eutrophic environments during the emptying and minimum level phases. However, during the maximum level phase, taxa generally found in more oligotrophic systems were observed here also. Similar to other disturbed systems, the zooplankton assemblage was dominated by Rotifera, except in summer and autumn when the cladoceran Ceriodaphnia quadrangula and/or the copepod Tropocyclops prasinus became dominant. Although those shifts seem to be related to water level variations, further research is needed to evaluate to what extent they might also be induced by other seasonal factors acting independently of water fluctuations. Based upon the obtained data, suggestions for reservoir management are proposed.

Neogastropod molluscs from the Miocene of western Amazonia, with comments on marine to freshwater transitions in molluscs

Two neogastropod species occur in brackish intervals in the Pebas Formation (late Middle to early Late Miocene) of Peru and Colombia in western Amazonia.Purpura woodwardiRoxo, 1924, is assigned toMelongenaSchumacher, 1817 (Melongenidae), and ?Nassarius reductus(Nassariidae) is recognized as a new species. These gastropods are among the very few marine invaders in the otherwise freshwater Pebas fauna. The small number of marine to freshwater transitions among South American molluscs contrasts with the situation among South American fishes and southeast Asian molluscs. It may be related to seasonal fluctuations in water level and anoxia in present-day South American freshwater environments, as well as to predation and productivity.

NEOGASTROPOD MOLLUSCS FROM THE MIOCENE OF WESTERN AMAZONIA, WITH COMMENTS ON MARINE TO FRESHWATER TRANSITIONS IN MOLLUSCS

Abstract Two neogastropod species occur in brackish intervals in the Pebas Formation (late Middle to early Late Miocene) of Peru and Colombia in western Amazonia. Purpura woodwardiRoxo, 1924, is assigned to MelongenaSchumacher, 1817 (Melongenidae), and ?Nassarius reductus (Nassariidae) is recognized as a new species. These gastropods are among the very few marine invaders in the otherwise freshwater Pebas fauna. The small number of marine to freshwater transitions among South American molluscs contrasts with the situation among South American fishes and southeast Asian molluscs. It may be related to seasonal fluctuations in water level and anoxia in present-day South American freshwater environments, as well as to predation and productivity.

Secular Changes in Great Lakes Water Level Seasonal Cycles

The three primary scales of Great Lakes water level fluctuations are interannual, seasonal, and episodic. Of these three, the seasonal water level fluctuations have received relatively little attention. The Great Lakes water levels have a well defined seasonal cycle driven primarily by snowmelt in the spring and summer and lake evaporation in the fall and winter. The present average seasonal cycle ranges from 26 cm on Lake Superior to 38 cm on Lake Ontario. Great Lakes monthly water levels from 1860 to 2000 were used to assess changes in the seasonal cycle of each of the Great Lakes and Lake St. Clair over the past 140 years. Changes are found on all of the lakes during the period of record. They usually resulted in a decrease in seasonal range and a time shift in the months of seasonal maximum and minimum. The effects of lake regulation were found to be negligible in the case of Lake Superior and significant for Lake Ontario. The major changes on Lakes St. Clair and Erie are likely a result of changes in the connecting channels ice retardation rather than changes in seasonal hydrometeorology. Seasonal cycle regimes are delineated for each of the lakes and possible rationale for the changes discussed.

Resource Variability and Conservation of American Flamingos in Coastal Wetlands of Yucatan, Mexico

Wetlands are characterized by seasonal rainfall and water level fluctuations; hence, knowledge about strategies used by waterbirds in response to such variability, particularly extreme variations, is necessary for implementation of conservation strategies. In 1994-95, we sampled the potential food available to American flamingos (Phoenicopterus ruber ruber) using the coastal wetlands of the Yucatan Peninsula, Mexico, and we documented flamingo behavior over an annual cycle at 2 important flamingo sites in Yucatan (the Celestun Lagoon and Uaymitun wetlands) to examine possible factors affecting flamingo distribution and movement patterns. Environmental conditions fluctuated differently at the 2 sites. We found 3 plant items and 9 invertebrate taxa that are potential food items for flamingos in Celestun, but only 5 of these invertebrate taxa were in Uaymitun. The most abundant food items occurred at both sites, but in greatly different proportions. Flamingos foraged in distinct groups and there was high variation among food samples within sites (CV = 92% in Celestun, 125% in Uaymitun); hence, food probably was patchily distributed. Food decreased in abundance from the wet to the dry season in Celestun and increased toward the beginning of the dry season in Uaymitun (P < 0.05). Some behavioral attributes, mean flock size (Celestun: x = 299; Uaymitun: x = 223), and the percentage of flamingos feeding (Celestun: x = 54; Uaymitun: x = 57) were not different between sites, but there were differences within sites and seasonal differences between sites during some sampling periods. Flamingo numbers at the 2 sites did not reflect food abundance, but selection of foraging sites may also be influenced by water depth. Overall, hurricanes appear to be the major allogenic factor affecting wetland habitats of the Yucatan Peninsula wherein flamingos must respond to the interaction among food density, food quality, food availability (i.e., water depth), and salinity when selecting foraging sites. These fluctuations in environmental conditions create a variable food base that results in spatial shifts in the availability and quality of foraging habitat. This information demonstrated that the landscape-level needs of the flamingo population in Yucatan include availability of multiple foraging sites within the 8,000-km 2 coastal wetland complex along the Yucatan Peninsula.

The archaeological importance of Llangorse Lake: an environmental perspective

1. The Llangorse crannog is an unique example of an Irish monument type constructed in Wales. The combination of artefact dating, dendrochronology and historical sources suggests it was constructed in the late 9th century by the king of Brycheiniog and destroyed in AD 916 by a Mercian army. 2. Wave erosion, seasonal water level fluctuations, root growth, and tourist activity all pose a serious threat to the site where anaerobic conditions have preserved timbers, artefacts (including unique cloth finds and bone), and environmental indicators which are currently unique in Wales and of international historical importance. 3. Only a small part of the site has been archaeologically investigated and management strategies to preserve the site without conflicting with other environmental interests are still under consideration. 4. The archaeological investigation of Llangorse crannog has provided an opportunity to study the early medieval environment of the lake, including rates of erosion and colonization by vegetation of the island. 5. The vulnerability of the crannog is discussed, and strategies for conservation reviewed. Copyright © 1999 National Museums and Galleries of Wales

The archaeological importance of Llangorse Lake: an environmental perspective

1. The Llangorse crannóg is an unique example of an Irish monument type constructed in Wales. The combination of artefact dating, dendrochronology and historical sources suggests it was constructed in the late 9th century by the king of Brycheiniog and destroyed in AD 916 by a Mercian army. 2. Wave erosion, seasonal water level fluctuations, root growth, and tourist activity all pose a serious threat to the site where anaerobic conditions have preserved timbers, artefacts (including unique cloth finds and bone), and environmental indicators which are currently unique in Wales and of international historical importance. 3. Only a small part of the site has been archaeologically investigated and management strategies to preserve the site without conflicting with other environmental interests are still under consideration. 4. The archaeological investigation of Llangorse crannóg has provided an opportunity to study the early medieval environment of the lake, including rates of erosion and colonization by vegetation of the island. 5. The vulnerability of the crannóg is discussed, and strategies for conservation reviewed. Copyright © 1999 National Museums and Galleries of Wales

TAILINGS BASIN RECLAMATION ATLANTIC CITY moN MINE, WYOMING

An 81 ha (200 ac) tailings impoundment at a taconite operation in Wyoming abandoned in 1985 has been a source of blowing dust. The site qualified for reclamation under Wyoming's Abandoned Mine Land program. The reclamation design included: incorporating commercially available organic amendments and fertilizers into a 300 mm (12 in.) thick cap of a sterile gravelly clay loam cover material, planting trees in the protective wind/snow shadows of rock beams and rock snow fences, lowering the water level n a flooded mine pit that was feeding uncontrolled seeps, and constructing a wide tailings pond spillway that allows flood control while minimizing seasonal water level fluctuations in the pond. The construction of the earthwork aspects of the design were completed over two construction seasons, including work during the winter at this high-altitude (2,470 m [8,100 ft.]) site. This occurred because snow from an early winter storm that collected behind the rock beams and rock snow fences was slow to melt. Furthermore, the increased snow catch made the site too wet the following spring to allow seeding during the normal seeding window; a fall planting was necessary. The rocky nature of the cover material prompted the development of innovative reclamation approaches,more » including fabricating a rock rake bulldozer blade and applying organic soil amendments by aerial spraying. A randomly-configured two-acre test plot was installed to evaluate the benefits of various soil amendments as the site matures. Future work on the site will include tree seedling planting and plugging of a decant pipeline.« less

Establishment of Native Aquatic Plants for Fish Habitat: Test Plantings in Two North Texas Reservoirs

ABSTRACT Test plantings of native aquatic plant species were made in two Texas reservoirs. Founder populations of three native submersed or floating-leaved species were established within small (2- × 2-m) exclosures utilizing actively growing transplants. Herbivory and excessive sedimentation proved to be deterrents to plant survival and expansion. Nine small founder populations of Vallisneria americana were established within North Lake, a small reservoir with limited water level fluctuations and a developing community of native pioneer aquatic plants. Plants within all nine exclosures successfully established and began vegetative growth. In intact exclosures, the plants rapidly covered the sediment surface within the exclosures. Expansion beyond the exclosures was variable and occurred primarily during the cooler portions of the year when herbivory was assumed to be low. During the spring of the second growing season, herbivores cropped most of the previous expansion leaving only a narrow fringe of plants surrounding the exclosures. At Lewisville Lake, a large, turbid reservoir with significant seasonal water level fluctuations and no existing aquatic macrophytes, two native pioneer species (Potamogeton nodosus and Heteranthera dubia) were planted within exclosures. Good survival and growth occurred within undamaged exclosures, although no expansion ever occurred outside the fenced areas. Plantings of H. dubia in undamaged exclosures also showed excellent survival except for those planted in areas subject to very high turbidity and sedimentation rates. Again, herbivory prevented any expansion outside the protective exclosures.

Seasonal changes in condition, nutrition, gonad maturation and energy content in barbel, Barbus sclateri, inhabiting a fluctuating river

The objective of this study was to investigate the seasonal cycle of condition, nutrition and gonad development, as well as the magnitude of seasonal variations in energy content of somatic and gonad tissues in juveniles, males and females of Sclater's barbel, Barbus sclateri, from the upper Guadalete River (south Spain). The influence of reproductive cycle on somatic changes was also investigated and discussed. Measurements of condition factor (K), somatic index (SI), gonadosomatic index (GSI) and somatic and gonad energy content (J g-1 dw) were made in individual specimens taken from the Guadalete River monthly for 12 months. This freshwater ecosystem is characterised by strong seasonal fluctuations in water and flow level, temperature and food supply. It was found that in general juveniles, males and females of barbel exhibited a similar condition, nutrition and somatic energy cycle throughout the year, with the highest values in spring and the lowest in summer. Depletion of K, SI and somatic energy storage from spring until mid-summer seems to be associated with high metabolic demands during this period, and in adult fish also with spawning-related activity. The gonad index and energy content of the gonad were the highest in April and the lowest in summer for both sexes. Spawning took place during late spring – early summer, with fish quiescent by mid summer. The energy required for ovarian development (3970 J g-1 dw) was greater than the one for testes development (2763 J g-1 dw). Data on gonad energy content indicated a period (March to April) of intense energy accumulation (64% males and 37% females) which was related to the decline in the average somatic energy content in males and females. The somatic energy content was linearly related to K and SI. In the same way, GSI correlated positively with gonad energy. Linear trends were found between somatic parameters (K, SI and energy content) and gonad parameters (GSI and energy content).

Evaluation of eutrophication control strategies for the Keban Dam reservoir

The reservoir of the Keban Dam in eastern Anatolia is a very deep and large water body subject to significant seasonal water level fluctuations within a given hydrological year. At the present time, different sections of the reservoir have different trophic status and the upper portion of the reservoir, in particular, is eutrophic. In this regard, there is a need for the assessment of alternative strategies to be implemented for phosphorus and thus eutrophication control in this segment of the reservoir. In this study, mathematical modeling techniques are used to compare various alternatives in terms of their relative effectiveness for phosphorus control. With this intention, a two dimensional depth-averaged hydrodynamic model and a three-dimensional compartmental water quality model are coupled to represent the complex water body dynamics prevailing in the reservoir. After calibration and verification, the coupled model was used to simulate dissolved oxygen and euphotic chlorophyll- a concentrations under different scenario conditions corresponding to various strategies proposed for phosphorus control. The modelling effort has yielded valuable information that can be used by decision makers for the evaluation of different management alternatives including reduction of the phosphorus load coming from point as well as diffuse sources within the catchment area, use of baffles and construction of pre-dam structures.

The palaeoecology of a treed bog in western boreal Canada: a study based on microfossils, macrofossils and physico-chemical properties

The developmental histories of a wetland and the surrounding upland vegetation in the southern boreal region of western Canada are traced through microfossil, macrofossil, physico-chemical and radiometric analyses of a 425 cm deep core consisting of sandy gyttja and peat. Microfossil analysis includes algal, fungal and zoological ‘Types’ which are illustrated and described, with notes on their occurrence as observed in several peat sequences of western boreal Canada. Local wetland development started in the central area of a 65 ha closed depression at c. 5000 BP, due to a rise in the groundwater table related to a gradual increase in effective precipitation in the region. Initial stages were characterised by Typha-dominated marsh communities that suggest marked seasonal fluctuations in local water levels. The accumulation of organic matter could not keep pace with the ever-rising groundwater table, and a shallow eutrophic pond with aquatic macrophytes developed locally. The body of open water was surrounded by marsh vegetation that was gradually being displaced towards the margins of the depression. At 4330 BP moist conditions became prevalent throughout the growing season. A brown-moss dominated treed rich fen replaced the shore marsh community and gradually began to encroach on the small pond. The basin completely terrestrialised at 3260 BP. Autogenic processes caused by peat accumulation resulted in a transition towards a Sphagnum-dominated treed poor fen. At 2790 BP a treed bog became established, firstly dominated by Sphagnum angustifolium and S. magellanicum indicating moist local conditions. After 1870 BP S. fuscum became dominant, indicating drier conditions locally. The upland vegetation just before local wetland formation was characterised by Picea in relatively wet depressions and by Populus in drier areas. Some grassland patches were present, most probably on the more southerly exposed slopes of the hills. Picea was locally displaced by wetland vegetation at c. 5000 BP, whereas deciduous forest and some grassland stands continued to dominate the surrounding hills. The coniferous taxa Pinus and Picea began to invade the uplands after 4330 BP, contemporaneously with the development of the local peatland. This marks the time at which the modern southern boreal ecosystem dominated by peatlands in lowlands and mixed wood forest in uplands became established in the area.

Seasonal variations in the physiological status and energy content of somatic and reproductive tissues of chub

The seasonal fluctuations in condition, nutrition and somatic energy content, and gonad development cycle were investigated in chub Leuciscus pyrenaicus from the headwaters of the Guadalete River, a freshwater ecosystem characterized by strong seasonal fluctuations in discharge and water level, temperature and food supply. The relationship between somatic stage and gonad cycle was also investigated and discussed. Condition, nutrition and somatic energy cycles could be divided into two distinct periods: from April to January with summer decreases and autumn increments, which is common for juveniles and mature fish; and from January to March, when juveniles and mature fish displayed different temporal variations related to the reproductive cycle. Gonad development took place from the end of the winter into the summer, the testes developing before the ovaries. Spawning started in late spring (May) and continued into summer (June and July), with fish quiescent by autumn (September). The results suggest that, for L. pyrenaicus, both environmental factors (e.g. food supply, water temperature) and reproduction needs affect the condition, nutrition and somatic energy storage of fish, which have been used as indicators of the physiological status of the population.

La régulation du lac du Bourget (France) : nouveau fonctionnement hydraulique, impacts environnementaux / Regulation of the lac du Bourget (French Alps) : environmental impact of new management rules

Abstract : Regulation measures for the lac du Bourget has involved the introduction of a year-round management system, resulting in a reduction in seasonal waterlevel fluctuations. Shores have seen both a dramatic drop in the high water levels of spring and summer, and the disappearance of water-free periods in autumn following the elimination of natural low water levels. As a result of these changes in the operation of the entire lake ecosystem, wetlands have become severely limited in extent, leading to an impoverishment of the scape and a reduction in biodiversity. The article concludes by proposing new hydraulic regulation measures which attempt to take into account socio-economic interests without/forgetting environmental requirements/ sacrificing/jeopardising/the physical environ-

Spatial and seasonal variation of methane emission from an Amazon floodplain lake

Methane (CH4) emission from a floodplain lake in central Amazonia was measured during a complete annual cycle using a static chamber method. The results show significant differences in the CH4 flux rates from different habitats in the lake: open water, floating vegetation (mainly the aquatic grass Paspalum repens) and floodplain forest. The highest CH4 emission rates (10–198 mg CH4 m−2 d−1) were recorded during inundation in the seasonally flooded forest. Lower emission rates occurred in the floating vegetation (3–79 mg CH4 m−2 d−1), which is found in areas with a short subaerial phase and in the permanently aquatic part of the lake (4–65 mg CH4 m−2 d−1) free of macrophytes and with the lowest productivity. Seasonal fluctuations in water level resulted in distinct seasonal patterns in CH4 release at different sites in the lake. The permanently aquatic part of the lake had lowest emission rates during periods of water inflow and subsurface oxygen replenishment into the lake. At the periodic aquatic...

Platforms in the akalche at E1 Mirador, Peten, Guatemala and their implications

AbstractLate Preclassic Period platforms were surveyed and test‐excavated in a seasonal swamp or akalche, at the large ancient lowland Maya site of El Mirador in Peten, Guatemala. Pedological, hydrological, and archaeological evidence suggest that the climatic and hydrological regimes were drier than they are today to permit habitation and warrant the investment in labor. Nevertheless, observations of present conditions, including the clayey soils, indicate that the akalche was almost as inhospitable in antiquity as it is today, that it had the same extremely poor agricultural potentials and that intensive wetland cultivation would have necessitated sizeable investments in dams to dampen the extreme seasonal fluctuations in water levels. Dams are not observed, and evidence is elicited to indicate that they would be readily observable today had they been emplaced here in antiquity. We offer evidence suggesting that these platforms had domestic functions, but we are forced to conclude that intensive wetland cultivation did not sustain them nor this large regional center as a whole. We argue, instead, that these habitations constitute evidence for population pressures on urban upland resources, especially building sites and perhaps agricultural land. Akalche households appear to have sustained themselves, at least in part, by foraging for animal and plant foods, cordage products, building materials, and firewood. The data are inadequate to decide if these structures housed full or part time specialists, or if they were self‐sufficient in subsistence. © 1994 John Wiley &amp; Sons, Inc.