Mainstream Water Research Articles

The role of recharge zones, discharge zones, springs and tile drainage systems in peneplains of Central European highlands with regard to water quality generation processes

The hydrogeology, runoff generation and water quality generation in old peneplains of Central Europe built by acid crystalline rocks (such as the Bohemo-Moravian Highland) are described and interpreted in terms of a three-zone concept. The recharge zones are located on flat tops of hills and their soils are mostly permeable. It is mainly through them that the shallow groundwater-bearing formations are loaded with nitrate. The groundwater exfiltrates on the lower parts of slopes (in the so-called transient zone) and in narrow valleys (in the discharge zone), creating dispersed springs and waterlogged areas. In addition, the rapid and shallow flow of perched groundwater down the slope, which takes place during wet periods in the recharge zone and, mainly, in the transient zone, leaches the nitrate from the soil directly to the stream, without necessarily being in contact with the permanent groundwater table of the recharge and the transient zones. Discharge and water quality measurements in the Kopaninský tok experimental catchment (6.7 km 2) were analysed, using a combination of two runoff separation techniques (a digital filter and a simple conceptual model GROUND). Three runoff components were distinguished (direct runoff, interflow and baseflow). There is a weak but significant positive correlation between the stream nitrate concentration on the one hand and either the interflow or the baseflow on the other hand. There is also a weak but significant negative correlation between the stream nitrate concentration on the one hand and either the ratio of direct runoff to total stream flow or the logarithm of this ratio on the other hand, provided that the cases of zero direct runoff are disregarded. A simple mixing model was used to estimate the characteristic nitrate concentrations of individual runoff components. The interflow has the highest characteristic nitrate concentration and is probably the main stream water polluter with nitrate. The baseflow is identified as the likely second main polluter. The differences in water quality between a drainage outlet and a forest spring indicate the importance of a proper nitrogen management in the recharge zones. It is also concluded that the tile drainage and tillage of formerly waterlogged sites, mainly located in transient zones, reduce the opportunity for denitrification of both baseflow and interflow. The ploughed lands in the recharge zones represent an established basis for local agriculture and cannot be easily set aside. Many such lands have been declared as vulnerable to nitrate pollution in order to protect waters against impacts of risky agricultural practices. It is proposed that some waterlogged and drained sites in the transient and discharge zones are set aside rather than the flat ploughed lands on the hill tops. To increase the denitrification, tile drainage runoff from the transient and the discharge zones should be retarded.

Palaeoenvironmental reconstruction of dinosaur nesting sites based on a geochemical approach to eggshells and associated palaeosols (Maastrichtian, Provence Basin, France)

Variability of the stable isotopic (δ 13C and δ 18O) and trace element (Mg, Sr, Fe, and Mn) content from dinosaur eggshells from the Provence Basin has been addressed by considering the stratigraphic distribution of the eggshells, the palaeoenvironments, and the chemical content of associated sediments. Preferentially, in situ eggshells were analysed. Samples were collected from two sections, one belonging to the floodplain (Roques Hautes) and the other to the channel belt (Rousset–Bréguières), as determined from sedimentological criteria. On a regional scale, this combined analysis provided new insights into palaeohydrology, vegetation cover and dinosaur behaviour. Different sources of drinking water were identified: (1) the main stream waters with significant salinity levels, (2) lateral feeders with water composition close to that of precipitation. Water composition is reflected in the eggshell trace element contents: a high Sr content for the eggshells from the channel belt (mean 1200 ppm) contrasting with the very low values for the floodplain (mean 250 ppm). During the first part of the Maastrichtian, evaporation rates were quite significant, as seen from the 1.5‰ difference between the eggshell δ 18O (drinking water) and the palaeosol carbonate nodules (precipitation). This contrast diminished and became nearly insignificant in the second half of the Maastrichtian. Vegetation was composed of C 3 plants and two ecosystems are reconstructed: a riparian forest extending along the channel belt and open vegetation in the floodplain. The contrasted isotopic and trace element content of the eggshells was a crucial factor in identifying animal migration from one site to another. Migration was quite limited, suggesting that the animals settled for some time at the places where they laid their eggs. Intraspecific variations among modern birds are well correlated with the environment and may be greater than interspecies variations, which limits the potential of geochemical analysis to characterise dinosaur species.

Public participation in integrated water resources management: the case of Tanzania

Effective and sustainable management of water resources is vital for ensuring sustainable development. However, efforts of water resource management seem to demonstrate inappropriate practices, especially when compared to water consumption trends in developing countries in general, and sub-Saharan Africa in particular. Being a major and vital ingredient to human kind, water resources influence all sectors. However, there have been increased problems over time that subject water resources to a number of crisis and pressures. Poor water resources management have stimulated and sustained a number of problems related to health, socio-economic and environment, which need to be solved. These problems are accelerated and magnified by the countries’, communities’ and individuals’ struggles for economic and social development as many development initiatives are affected by water availability and vice versa. Integrated water resources management (IWRM), is a process, a change, and an approach that mainstream water resource use and management into the national economic in an equitable manner without compromising the sustainability of vital ecosystems. This paper analyses the importance of community participation in the process of IWRM. The paper describes reasons that justify the need for an IWRM approach and explains the rationale for community participation. Successful cases in community involvement have been cited from different areas to demonstrate the importance of IWRM. The paper concludes that the public/community involvement is crucial for a successful and sustainable water resource management. It has been emphasized that natural resources management related policies including water requires the use of knowledge, experience and opinions of local communities who are the key stakeholders in resource conservation. This could be ensured through public/community participation.

Weathering processes in the Ganges–Brahmaputra basin and the riverine alkalinity budget

We present river chemistry data for a network of rivers draining the western and central Nepal Himalaya. Our sampling locations cover the system from the sources of rivers in Tibet to the Gangetic plain. Water samples were collected throughout the year, including the monsoon season, for rivers in Nepal and for the Ganges and Brahmaputra in Bangladesh. Rivers draining the North Himalaya are characterized by low discharge under a cold and arid climate. Main stream waters have δ13CDIC near 0‰ and high [SO42−]/([SO42−]+[HCO3−]) ratios (XSO4) with values around 40 Eq% and high [Cl−]. Ca is the dominant cation (Ca2+/∑cations=55 to 75 Eq%, after correction of sodium by chloride). Dissolved sulfate is produced in waters from the Tethian Sedimentary Series whereas chlorine is related to thermal waters. Dissolved sulfate is primarily derived from sulfide oxidation rather than evaporite dissolution. δ13CDIC values of up to 3.9‰ show that metamorphic CO2 is an important weathering agent. Rivers of the North Himalayan basins have about 50% of their alkalinity derived from carbonate dissolution, 20% from biogenic activity and 30% from metamorphic CO2. On the south flank of the Himalaya, rivers are more depleted in 13C and have, on average, lower XSO4. Most rivers have δ13CDIC and XSO4 values compatible with a simple mixing between soil CO2 and sulfate derived from sulfide oxidation. During the monsoon, discharge increases by a factor 20 but the total dissolved concentration is only slightly reduced. XSO4 and δ13C decrease while Ca/∑cations increases, implying enhanced dissolution of pedogenic calcite. As a whole, the G–B riverine flux of alkalinity derived from silicate weathering is around 2.7×1011 mol/year, modest at the global scale. Sulphuric acid controls 20–30% of the weathering reaction in the Brahmaputra and 6 to 9% in the Ganges. Na+ and K+ balance 60 to 65% of the silicate-derived alkalinity flux, and the long term CO2 consumption by Ganges and Brahmaputra is near 6.4×1010 mol/year. The flux of metamorphic CO2 converted to alkalinity via weathering reactions is ca. 1×1010 mol/year.

A mass balance approach to estimate the dilution and removal of the pollutants in stream water polluted by acid mine drainage

A few simple mass balance equations were developed to simultaneously estimate how much the pollutants from acid mine drainage (AMD) in stream water are diluted and removed during their migration. The application of the equations requires knowledge of the variations in the concentrations of the dissolved pollutants and the stoichiometry of the precipitation reaction of the pollutants when none of the pollutant shows a conservative behavior along the stream path. The calculation should be restricted to the pollutants showing much higher concentrations in the polluted main stream water than in the combining or diluting water of the same target area. The mass balance equations were applied to estimate the dilution factor and precipitation fractions of pollutants in Imgok Creek such as Fe, SO4 and Al from the AMD of Yeongdong mine. The results show that the estimation, especially for SO4 and Al, significantly depends on the kinds of the precipitates. When FeOHSO4 and AlOHSO4 are assumed to precipitate, the maximum removal fractions of SO4 and Al by precipitation are respectively 34% and 46% of the original input, which is much higher than the values estimated when SO4 is considered to be perfectly conservative. It indicates that the stoichiometry of precipitation reaction is very important in the interpretation of the pollutant dilution and migration and assessment of environmental impacts of AMD. The applicability of the mass balance equations may still need to be verified. However, examining the calculated dilution factor and precipitation fractions with the equations can provide invaluable information on not only the behavior but also unexpected input of the pollutants in the stream water polluted by AMD and other point sources.

Spatial and temporal variabilities in nitrogen and phosphorous in the Nakdong River system, Korea

The concentrations of nitrogen (N) and phosphorous (P) species and relevant hydrographic parameters were determined in main stream and tributary waters of the Nakdong River system during the periods of May through October 1994. During the entire period, the total N (TN) and total P (TP) concentrations in surface waters were found within the ranges of 0.4–7.0 (N=241) and 0.02–1.536 mg L-1 (N=241), respectively. To help derive meaningful interpretations of temporal and geographical variabilities in the nutrient bahavior, the entire data were evaluated for each individual parameter after employing several different grouping schemes. The results of this comparative analysis can be expressed in terms of: (1) high summer/fall ratios for most of nutrient species; and (2) low summer/fall ratios for most of nutrient-to-nutrient ratios and relevant hydrographic parameters. Interestingly, while the former case was found to be more significant in tributary waters than main stream waters, such geographical dependence was not strongly evident for the latter case. A z-statistic test, conducted to check the significance of temporal (between summer and fall) and spatial (between tributary and main stream regions) differences, confirm that the observed variabilities are in most cases strong enough for most of variables studied – nutrient species, their ratios, and relevant hydrographic parameters. In addition, comparison of nutrient species between dissolved and particulate phases reveals several interesting features. Unlike dissolved nutrient species, the concentrations of particulate N or P (PN or PP) exhibited quite extraoridanry behavior. While PN appears to be rather minor component of the total N budget for the Nakdong river, PP seems to make rather strong contributions to its total P budgets with its strong input from tributary waters during rainy summer season. Through an application of correlation analysis, relationships between different parameters were investigated for both before and after the grouping of data sets. The overall picture of this analysis showed that nutrient species were strongly correlated with each other, while the strongest correlations were among such hydrographic parameters as DO, BOD, COD, and conductivity. This analysis was further conducted to more deliberately divided data groups. The results of analyses on these sub-grouped data sets indicate that the occurrences of significant corelations were common from tributary waters relative to main streams for both (1) between different nutrient species and (2) between nutrient and hydrographic parameters. Using the line of evidence gathered from the statistical tests and from the correlation analysis, we conclude that the environmental health of the Nakdong river system is affected by the combined effects of various factors and processes.

The impact of airport de-icing on a river: The case of the Ouseburn, Newcastle upon Tyne

The damaging effects of airport de-icers to adjacent waterways have been suggested by a number of studies, but none have been able to demonstrate these effects in a field situation. The Ouseburn is a part-urban and partrural catchment of varied land-use and includes a tributary which drains the Newcastle International Airport. The tributary contributes only 3–5% of the river's average flow, yet it had a disproportionately adverse impact upon the river. This paper demonstrates how this was linked to the airport's winter application of urea salt de-icers. An integrated approach involving hydrological, chemical, bacteriological and macroinvertebrate sampling was used. During cold weather, higher levels of ammonia were recorded in the tributary and downstream, and concentrations peaked during runoff events. It is suggested that hydrolysis, facilitated by urea digesting bacteria, and surface runoff is the mechanism by which ammonia enters the stream. The airport tributary had a less diverse macroinvertebrate fauna than expected and had larger numbers of bacteria which were able to utilise urea. In-situ bioassay experiments found large deaths of Gammarus pulex (L.) and low biotic indices at a site downstream of the airport tributary confluence. Together with elevated ammonia levels this suggested that urea application adversely impacted on the main stream's water quality and ecology. The airport authorities have responded by changing to a less toxic de-icer.

Morphology and orientation of tube extensions on aggregations of the polychaete annelid Phragmatopoma californica

The morphology of organisms can influence fluid flow near their surfaces which, in turn, can influence the rates of mass exchange as well as the ability of the animals to capture and retain particles. In this paper, the morphologies and orientations of extensions on the tubes of aggregated individuals of the sabellariid polychaete Phragmatopoma californica from different habitats are described. The effects of these structures on fluid exchange and feeding-tentacle deflection are also assessed. The tube shape of aggregated P. californica varies among habitats. In exposed habitats, extensions on tubes (flares) encircle the entire circumference of the worms' apertures. In more protected habitats, extensions (hoods) partially encircle the circumference of apertures and are oriented so that the opening of the hood faces into the predominant direction of water flow over the aggregation. After the surface structures are damaged, hoods are repaired more quickly than flares. In this study, all damaged hodds were repaired within 24 h while flares were fully repaired only after 240 h. The repaired hoods are oriented in the same direction as the original structures Both hoods and flares decrease the rate of fluid exchange between the aggregation surface and the mainstream water flow. These structures also decrease the deflection of the feeding tentacles by the water flow. The orientation of the hoods relative to the direction of water flow affects both the rates of fluid exchange and the deflection of the tentacles.

Chance Constrained Model for River Water Quality Management

A chance constrained model is proposed, in which the main stream, tributaries, and storm water are considered as random variables to determine the most economical level of wastewater treatment at each discharge city or industry along a river basin. The model considers the risk of violation of the stream‐water quality explicitly and therefore, provides a more rational approach than the traditional design value or safety factor approach, e.g., the lowest 7‐day moving average of daily flow rate over a 10‐yr period. The model is shown to be equivalent to a linearly constrained program, thus enabling the application of simple solution techniques.

Longitudinal dispersion in a forest stream

A forest stream typical of those found in SE Belgium and NE France has been studied with respect to the parameters determining the dispersion of a non-reactive solute in a streamflow with stagnant zones. Non-linear adjustment of an analytical solution of two partial differential equations describing longitudinal dispersion and solute exchange between main stream and stagnant water provided a set of parameters describing satisfactorily the experimental results. The dead-zone fraction diminished very rapidly as soon as the flow rate increased beyond a fairly low value and remained constant thereafter. The longitudinal dispersion coefficient followed an inverse pattern but in a somewhat less regular way. Attempts were made to correlate these changes with the Darcy—Weisbach friction factor.

Strontium isotopes in selected streams within the Susquehanna River Basin

The concentration and isotopic composition of strontium in water samples from the Susquehanna River and its major tributaries between Northumberland, Pennsylvania, and the Chesapeake Bay have been determined to investigate the usefulness of the 87Sr/86Sr ratio as a tracer in hydrologic studies. The87S/86Sr ratios of tributaries, measured just upstream from their confluence with the Susquehanna, show considerable variation, ranging from 0.7091 to 0.7218. These ratios appear to be determined primarily by the local bedrock type and aquifer characteristics. Tributaries whose drainage basins contain important carbonate aquifers have relatively high Sr concentrations and 87Sr/86Sr ratios of about 0.709; where the bedrock is shale with no carbonate rock, the tributaries are characterized by much lower Sr concentrations and 87Sr/86Sr ratios of about 0.716. Tributaries in metamorphic bedrock also have low Sr concentrations and isotopic ratios averaging 0.719. The 87Sr/86Sr ratios of nearly all tributaries in the study area seem to represent a mixture of varying proportions of two distinctly different groundwater types, one with a high Sr concentration and low 87Sr/86Sr ratio, the other characterized by a low Sr concentration and relatively high 87Sr/86Sr ratio. In the northern half of the study area, marked variations in the 87Sr/86Sr ratio of the Susquehanna River indicate incomplete mixing of tributary and mainstream waters, apparently due to the extreme width and small depth‐to‐width ratio of the Susquehanna. Under favorable geologic and hydrologic conditions, strontium isotopes have potential as a tracer of water provenance.

Biological and bacteriological examinations of Calway city water supply during two years.

An account is given of the problems encountered in the examination of the Galway city water supply. The findings in the piped samples are discussed and the reasons prompting a survey of the main stream and Lough Corrib water are given. The biological and bacteriological findings in the river water are discussed. The plankton deposits are described, and their effect on the raw water discussed. Possibilities in the development of the water supply scheme are given, with the probable effect of the algal deposits, unless these are controlled.