Water Quality Regimes Research Articles

Mathematical model of the oxygen regime of Cartagena Bay

A mathematical model of eutrophication/oxygen regime for Cartagena Bay (Colombia) is described. The model consists of hydrodynamic and biogeochemical blocks to assess engineering alternatives for improving the water quality and oxygen regime in the bay. The hydrodynamic block of the model is based on the primitive three-dimensional equations for estuarine and coastal dynamics. The biogeochemical block includes the balance equations for the following components of the ecosystem: phytoplankton, bacteria, detritus, dissolved organic matter (DOM), phosphate, ammonium, nitrite, nitrate and dissolved oxygen. A non-traditional parameterization of bacteria role in biochemical oxidation of organic matter is used. Modelling of distinct ecological situations for Cartagena Bay has shown the principal strategic objectives to improve the water quality of the bay. The model has been tested and could be applied to other similar water bodies.

Climate, Hydrochemistry and Economics of Surface-water Systems (CHESS): adding a European dimension to the catchment modelling experience developed under LOIS

One achievement of the UK Land–Ocean Interaction Study (LOIS) was to link dynamic biogeochemical models of different domains, e.g. rivers, estuaries and coastal waters, and to use the linked model to investigate possible changes from the current status that might occur in the future, for example as the result of climate change. The Climate, Hydrochemistry and Economics of Surface-water Systems (CHESS) project has taken the LOIS methodology forward by exploring possible impacts of climate change on the water quality of European rivers, with the purpose of informing future catchment management. This was achieved by the application of a standard modelling framework to a set of five European catchments located in Finland (River Vantaa), United Kingdom (Yorkshire Ouse), Belgium (Dender), Italy (Enza) and Greece (Pinios). Baseline conditions were simulated using existing meteorological data from the period 1961–1990, and in all cases the modelling framework was able to reproduce key features of the flow and water quality regimes of the study catchments. The modelling framework comprised two models. The Soil Water Assessment Tool (SWAT) was used to simulate water and chemical fluxes, primarily nutrients and sediment, generated from diffuse areas and thereby provide sub-catchment inputs to an in-stream water quality model, the Quality Evaluation and Simulation Tool for River Systems (QUESTOR). QUESTOR integrated the diffuse runoff along the channel network, together with point source discharges from industry and sewage treatment works, and water abstractions for public supply, industry and agriculture. The modelling framework has been used for the baseline conditions, along with a set of six climate scenarios. These comprised four scenarios derived from different general circulation models (GCMs) representing the 2050s, and three scenarios from the same GCM representing the 2020s, 2050s and 2080s, with one scenario in both groups. Results have been explored using a range of measures to reflect the different stakeholder interests within and beyond the catchment. The results reflect the variability in present day conditions (e.g. climate, soils, agriculture and industry), and the variability in the climate scenarios, both between-catchment and between-scenario. Specific examples are: the loss of the spring snowmelt causing high flows on the Vantaa; a decrease in the already very low summer flows on the Pinios; and significant seasonal changes in nutrient losses, even though the annual change is small.

Fish and fisheries of the tidal Thames: management of the modern resource, research aims and future pressures

In recent decades, following the cleanup in the 1960s, the Thames Estuary has become a major nursery ground for economic and conservation species, and has seen the development of substantial commercial and recreational fisheries. The Environment Agency has both sea fisheries and freshwater fisheries statutory powers in the estuary. A unique and focussed survey programme has been developed to inform management policies. A Fisheries Management Action Plan has been developed to promote integrated salmonid, eel Anguilla anguilla and sea fisheries management, promote nurseries, sustainable exploitation and habitat protection and enhancement. Data are used to influence water quality, water resources and flood defence management regimes and in the planning field to influence development proposals. Consensus and collaboration have been built through the Thames Estuary Partnership. Research aims identified through the Thames Estuary Research Forum are described together with future pressures on key species. The survey rationales being developed will contribute to new standard sampling strategies and classification scheme to meet the requirements of the E.U. Water Framework Directive.

Fish and fisheries of the tidal Thames: management of the modern resource, research aims and future pressures

In recent decades, following the cleanup in the 1960s, the Thames Estuary has become a major nursery ground for economic and conservation species, and has seen the development of substantial commercial and recreational fisheries. The Environment Agency has both sea fisheries and freshwater fisheries statutory powers in the estuary. A unique and focussed survey programme has been developed to inform management policies. A Fisheries Management Action Plan has been developed to promote integrated salmonid, eel Anguilla anguilla and sea fisheries management, promote nurseries, sustainable exploitation and habitat protection and enhancement. Data are used to influence water quality, water resources and flood defence management regimes and in the planning field to influence development proposals. Consensus and collaboration have been built through the Thames Estuary Partnership. Research aims identified through the Thames Estuary Research Forum are described together with future pressures on key species. The survey rationales being developed will contribute to new standard sampling strategies and classification scheme to meet the requirements of the E.U. Water Framework Directive.

From open sewer to salmon run: lessons from the Rhine water quality regime

The international regime for the River Rhine is widely considered to be unique. In this article, the author draws some lessons from the regime's development. These are related to two distinct strands in the literature. The first can be summarized under the heading of regime theory. It comprises studies dealing with the development of international regimes concerning water quality. These studies view the evolution of any such regime as determined by features of the issues in the light of relevant societal values and the role of transnational interest groups, scientific analysis and progress and the potential for interstate interaction. The second strand comprises aspects of negotiation theory. Its relevance suggests that there are options for trade-offs and that those options can have a positive impact. In addition, this literature helps to identify tactics that may be available to the negotiating parties. Most of these factors have had a positive impact. On the basis of an analysis of the historical development of the Rhine regime, this study elaborates upon three conditions that have had a positive impact on the development of the regime: the presence of an alert, creative and convincing party downstream; the existence of good international relations throughout the catchment area; and the presence of an international river commission, which could generate and disseminate information as well as facilitate negotiations among the riparian states.

OPTICAL CHARACTERISTICS OF NEW ZEALAND RIVERS IN RELATION TO FLOW1

ABSTRACT: Six years (1989–1994) of data from New Zealand's National Rivers Water Quality Network were used to characterize the optical water quality regime of river waters as regards: visual clarity (black disc visibility), turbidity, and light‐absorbing aquatic humic material (referred to as ‘yellow substance,’ measured as light absorption at 440 nm). Quantitative relationships between optical water quality variables and flow in rivers are well‐described by power law expressions. Visual clarity usually decreases strongly with increasing flow in individual rivers. There is a strong, inverse relationship between turbidity and visibility, but, because of differences between sites, turbidity is not a good general predictor of visual clarity (the attribute of real interest) in rivers. Yellow substance tends to increase with increasing flow, probably because during rainstorms, soil water high in yellow‐colored humic material, rather than rain water or ground water, dominates discharge. Therefore, rivers are typically clear and low in humic matter at low flow, and turbid and yellow‐colored at high flow.

Mathematical modeling of primary production and destruction of phytoplankton in operating and planned reservoirs

1. The proposed mathematical model of phytoplankton primary production and destruction permits estimating the dynamics of production and destruction processes both in operating and planned reservoirs as applied to the problem of calculating (predicting) the water quality and oxygen regime of these reservoirs. 2. A necessary condition of the practical use of this model is a preliminary determination of a number of its parameters on an operating reservoir-analog, the selection of which is not limited by any certain conditions related to its size, level of pollution, and trophic state, although, of course, it is advisable that it be close in these indices to the reservoir for which it serves as an analog. 3. The result of using this model for calculating phytoplankton primary production and destruction on an operating reservoir show that it reflects with less accuracy the dynamics of production and destruction during the growing season and with greater accuracy their annual values. 4. When using the given model for predicting phytoplankton primary production and destruction on operating or planned reservoirs it is advisable to calculate them in several variants with the use of various approaches to a determination of various parameters of the model so that the most preferable of the variants is selected in accordance with the purposes and tasks of predicting the water quality and oxygen regime of these reservoirs.

The influence of variable weather patterns on river water quantity and quality regimes

AbstractThere is growing awareness as to the potential sensitivity of hydrological systems to climate change. In particular long‐term changes in precipitation variability will have consequences for runoff regimes and thence solute transport. By utilizing the Lamb's Weather Type register in conjunction with observed 24 h rainfall totals it was possible to determine daily precipitation event probabilities and magnitudes for eight dominant synoptic classes. The stochastic rainfall series thus generated were then used to drive a robust hydrochemical model of an experimental catchment in the East Midlands, UK. The model results indicate that the frequencies of flood and drought are dependent upon the synoptic scenario, and especially the historical prevalence of both the anticyclonic and cyclonic patterns. Given that there have been marked fluctuations in the annual frequencies of these classes since the mid‐nineteenth century, long‐term variations in the severity and incidence of extreme flows may be anticipated. Clearly this will have major implications for the episodic export and dilution of solutes, sediments and microorganisms originating from both pristine and polluted hydrosystems.

Inter-basin Water Transfer: Ecological Concerns

The concept of transferring water from one river basin to another has evolved over centuries as a useful means of meeting water demands. However, such projects have the potential for serious ecological impacts, including introduction of nonindigenous organisms, changes in water quality and hydrologic regimes, and alteration of habitat. Although limited progress has been made in the last 20 years regarding our understanding of site-specific ecological consequences of inter-basin water transfer, research to date is inadequate for assessment of water transfer impacts. It is imperative that we develop coordinated research methodologies to be incorporated into the planning and evaluation of inter-basin water transfer projects.

Baseflow water chemisty in New Zealand rivers 2. Influence of environmental factors

Abstract Baseflow water chemistry in 96 New Zealand rivers was related to selected environmental variables quantifying lithology, land use, topography, and hydrology. The river sites were clustered using five water quality variables: major ions, phosphorus species, organic and nitrogen species, calcium, and nitrate. Eleven site clusters were identified and the differing water quality regimes discussed. The effect of the environmental factors on water quality was investigated using discriminant analysis. The resultant model assigned 73% of the sites to the correct cluster. The most important environmental variables determining water quality were hydrological variables such as specific yield, and proportional areas in the catchment of soft sedimentary rock, intensive pasture (which was negatively correlated with steep slopes and high altitudes), exotic forest, and volcanically derived rock. Multiple regression equations relating individual water quality determin‐ands to these environmental variables were de...

Human impact on rivers

Hydrologists from eastern and western Europe met at the U.K. Institute of Hydrology in Wallingford in November 1985 to launch a new environmental impact project, established under Project 6.1 of the UNESCO International Hydrological Programme. The work is being jointly funded by the United Kingdom, the Netherlands, Norway, and the Federal Republic of Germany; it will be based at Wallingford.The project will utilize the results of longterm monitoring of experimental and representative basins from a number of countries and includes the effects of man's activities (such as acidification, forestry, and groundwater pollution) on snow melt, flood and lowflow frequencies, and water quality regimes for both surface and groundwaters. There will be a strong emphasis on techniques for transferring results from experimental basins to ungaged regions.

Modeling inland water quality using Landsat data

The water quality parameters turbidity and algal pigment concentration of freshwater lakes have been modeled and predicted using Landsat multispectral scanner data as multiple linear predictors. Satellite data for an area in South East Australia from seven occasions during 1978 and 1979 were used along with concurrent ground-based measurements from sampling sites on three lakes covering a wide range of water quality regimes. Date-independent models for turbidity and algal pigment were obtained using the satellite multispectral data and the water quality data from up to 21 sampling sites on one lake on six occasions. The sun elevation at the time of satellite overpass was included in the models to account for differences between dates, and the time of sample collection was included to compensate for diurnal variations in pigment fluorescence. These models were used to successfully predict these water quality parameters for this lake on a new occasion and for the two other lakes on three occasions.

The effects of impoundment on the downstream macroinvertebrate riffle fauna of the River Elan, mid-Wales

River water quality and hydrological regime in the River Elan, downstream of an impoundment in an upland catchment in mid-Wales, were considerably different from a nearby naturally flowing river. Concentrations of total iron (mean, 0·26 and 0·61 mg litre −1 in May and September) and manganese (mean, 0·12 and 0·16 mg litre −1) were elevated in the River Elan compared with the nearby River Wye (iron ⩽ 0·16 mg litre −1, manganese ⩽ 0·01 mg litre −1). pH in the River Elan (5·3–5·5) was considerably lower than the naturally flowing River Wye (6·9–7·2). There were differences in riffle macroinvertebrates, generally collected with a cylinder sampler on two occasions, in the Elan and Wye. A number of taxa were not recorded or were found at relatively low densities in the River Elan; principally these included representatives of the Coleoptera, Ephemeroptera and Trichoptera, Additionally, total densities in the River Wye (mean, 4900 m −2 in May) were significantly ( p<0·05) higher than the Elan (mean, 900 m −2 in May). There was no evidence that effluents discharging to the Elan affected the distribution of macroinvertebrates. Differences between the fauna of the impounded River Elan and the naturally flowing River Wye probably resulted from the presence of iron- and manganese-rich deposits in the River Elan— probably derived from metal-rich water from the reservoir—although reduced pH and water temperature downstream of the impoundment could have contributed to the paucity of the fauna.

A square grid model for assessing the effect of alternative land uses on water quality

A mathematical model has been developed which can aid in assessing the effect of the modification of land use patterns on the water quantity and water quality regime of a watershed. The basin under study is divided into a number of elements using a square grid technique. The hydrologic and water quality components are evaluated at each element in the basin at successive time intervals, and flows are routed through the elements by use of a streamflow network system. The model can be used to assist in evaluating the effects of alternative land use configurations in a watershed, such as urbanization, the removal or growth of forests, the construction of dams, etc., on water quantity and water quality. It can also be used in the preliminary design of an urbanized area to estimate the size of storm sewers, artificial ponds, etc.