Integrated biogeochemical modelling of nitrogen load from anthropogenic and natural sources in Japan

This study proposed an integrated biogeochemical modelling of nitrogen loads from anthropogenic and natural sources in Japan. Firstly, the nitrogen load (NL) from different sources such as crop, livestock, industrial plant, urban and rural resident was calculated by using datasets of fertilizer utilization, population distribution, land use map, and social census. Then, the nitrate leaching from soil layers in farmland, grassland and natural conditions was calculated by using a terrestrial nitrogen cycle model (TNCM). The Total Runoff Integrating Pathways (TRIP) was used to transport nitrogen from natural and anthropogenic sources through river channels, as well as collect and route nitrogen to the river mouths. The forcing meteorological and hydrological data is a 30-year (1976–2005) dataset for Japan which were obtained by the land surface model, Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO). For the model validation, we collected total nitrogen (TN) concentration data from 59 rivers in Japan. As a comparison result, calculated TN concentration values were in good agreement with the observed ones, which shows the reliability of the proposed model. Finally, the TN loads from point and nonpoint sources were summarized and evaluated for 59 river basins in Japan. The proposed modelling framework can be used as a tool for quantitative evaluation of nitrogen load in terrestrial ecosystems at a national scale. The connection to land use and climate data provides a possibility to use this model for analysis of climate change and land use change impacts on hydrology and water quality.     

Modeling agricultural non-point source pollution in a high-precipitation coastal area of China

Non-point source （NPS） pollution simulation in the high-precipitation coastal areas of China is difficult because varying annual typhoon incidence leads to highly contrasting rainfall patterns in dry years and wet years. An IMPULSE （Integrated Model of Non-point Sources Pollution Processes） based NPS model of the Changtan Reservoir watershed, which is a typical high-precipitation coastal area in China, was established based on the analysis of point and NPS pollution data, a digital elevation model, and data on land-use, soil, meteorology, economy, and agricultural management practice. Pre-processed pre-rain- fall soil moisture levels were introduced during the simulation to model the effects of typhoons on hydrology. Rainfall events were simulated sequentially through the year and the model was calibrated and verified using hydrological and water quality data. Accuracy of the simulated rainfall runoff and water quality in the Changtan watershed was found to be acceptable. The study showed that the NPS modeling system could be applied to the simulation and prediction ofNPS loadings in the Changtan Reservoir watershed.     

Application of a water quality model in the White Cart water catchment,Glasgow, UK

Water quality models of urban systems have previously focused on point source (sewerage system) inputs. Little attention has been given to diffuse inputs and research into diffuse pollution has been largely confined to agriculture sources. This paper reports on new research that is aimed at integrating diffuse inputs into an urban water quality model. An integrated model is introduced that is made up of four modules: hydrology, contaminant point sources, nutrient cycling and leaching. The hydrology module, T & T consists of a TOPMODEL (a TOPography-based hydrological MODEL), which simulates runoff from pervious areas and a two-tank model, which simulates runoff from impervious urban areas. Linked into the two-tank model, the contaminant point source module simulates the overflow from the sewerage system in heavy rain. The widely known SOILN (SOIL Nitrate model) is the basis of nitrogen cycle module. Finally, the leaching module consists of two functions: the production function and the transfer function. The production function is based on SLIM (Solute Leaching Intermediate Model) while the transfer function is based on the flushing hypothesis which postulates a relationship between contaminant concentrations in the receiving water course and the extent to which the catchment is saturated. This paper outlines the modelling methodology and the model structures that have been developed. An application of this model in the White Cart catchment (Glasgow) is also included.     

Modelling of the relationship moisture content to nutrient transformation rate in river sediments

The modelling of the transformation processes in the river sediments is an important and still not investigated problem that is a key for water quality. The relation between nutrients transformation rate and moisture in sediments was investigated by means of analogous modelling. The mathematical dependences of the connection were derived, and only two of them were linear—at the early stage of COD (organic) change and at the late stage of transformation of phosphates that metabolically connected the biodegradation of organics with oxidative phosphorylation. The rest mathematical dependences were the polynomials of third order. This study confirmed that the leading factors which influence the transformation rate of nutrients are the sediment surface, particular organic matter and porosity of the medium, as well as the concentration on the sediment surface of micro-organisms, enzymes, co-metabolites, etc. The presented data from ecological modelling of the transformation processes in the parafluvial sediments showed how can the hydrological models be enlarged and enriched in their application to the key and critical (risk) fluctuations in the river functioning. The mathematical dependences and coefficients were extracted in our complex study to be included in HSPF model as an enlarged module. As far as the investigated transformation processes in the parafluvial have more universal significance, the results can be applied in the other models, bounded river water and sediment quality.     

A modeling system for drinking water sources and its application to Jiangdong Reservoir in Xiamen city

Drinking water sources are highly valued by authorities for safeguarding the life of a city. Models are widely applied as important and effective tools in the management of water sources. However, it is difficult to apply models in water source management because water managers are often not equipped with the professional knowledge and operational skills necessary for making use of the models. This paper introduces a drinking water source simulation and prediction system that consists of a watershed model, a hydrological model and a water quality model. This system provides methods and technical guidance for the conventional management of water sources and emergency water event response. In this study, the sub-models of the system were developed based on the data of the Jiangdong Reservoir in Xiamen, and the model validation was based on local monitoring data. The hydrological model and water quality model were integrated by computer programming, and the watershed model was indirectly integrated into the system through a network platform. Furthermore, three applications for Jiangdong Reservoir water protection utilizing the system were introduced in this paper, including a conventional simulation, an emergency simulation, and an emergency measures evaluation.     

Modelling the multiple nutrient limitation of algal growth

The way in which simultaneously limiting nutrients are supposed to act upon the algal growth rate is an important aspect of aquatic ecosystem modelling and research. Three different relations between the multiple nutrient limitation and two single nutrient limitations are developed from different biochemical models: a “multiplicative” relation, used in most dynamic ecosystem models, a new “sequential” relation and a “threshold” relation, sensu Liebig. The characteristics and practical consequences of these relations are investigated. By means of three experiments, derived from the literature, it is shown that the multiplicative relation yields the statistically significant worst growth rate predictions.     

Mathematical modelling and environmental decision-making

The primary role of a decision-maker is to make right decisions on the basis of available information and within the allowable time and resources constraints. The two basic types of models used for decision-making, technocratic and incremental, are discussed, and so are the common criteria of the decision-making process in a real world. The intensity and diversity of demands on our limited water resources have increased to such an extent that decision-makers are finding it increasingly difficult to consistently attain the needed flexibility and dexterity. Thus, even though decision-making has become exceedingly complex at present, and will become more so in the future, it is apparent that the average decision-maker has been provided with few, if any, new tools and concepts in the past several decades. One of these very few techniques is systems analysis.Even though modelling can add an important dimension to the decision-making process, surprisingly enough it still lacks credibility with the policy-makers. The several reasons that have given rise to this “credibility gap” are discussed in depth. Ten basic rules are suggested as guidelines for realistic model development. The positive and negative aspects of modelling as used for decision-making are discussed. Appropriate remedies are suggested to improve the image of modelling in the eyes of the decision-makers, which will reduce the proliferation of unvalidated, untested and unuseful models, much of which can be classified somewhere between dilettantism and academic exercises. It is concluded that even though some of our current models in this field are rather crude, and somewhat dependent on the experience and judgement of the analysts, the issue, in the final analysis, is very definitely on the side of having a model, even a crude one, against having no model at all.     

Dynamic simulation of water depletion in the root zone

The joint effect of the distribution of the soil water potential and of the root mass in the crop root zone upon the water uptake by the crop is represented by a simple equation. This expression is used to join a layered crop canopy model for finding the evapotranspiration, as controlled by stomatal action and the weather, with a hydraulic flow model for the root zone and the underlying soil. The complete model is used for the calculation of the water extraction pattern and the changes, with time, of other plant and soil processes. A simulation of a 20-day drying period is performed, using S/360 CSMP, for a constant diurnal weather pattern, and for a fully developed sorghum crop. The results show that, after a few days of essentially constant water use by the crop, a monotonic decline sets in, that is principally attributable to the decrease in transpiration. For the entire drying period a substantial amount of water - about 30% of the total used - is contributed by upward flow into the root zone from the soil below. The results demonstrate the difficulty of quantitative definition of concepts such as “field capacity”, “wilting percentage”, and “available” or “extractable” water.     

Analysis of spatial and temporal patterns in a large reservoir using water quality and hydrodynamic modeling

Effective management of reservoir water resources demands a good command of ecological processes in the waterbody. In this work the three-dimensional finite element hydrodynamic model RMA10 was coupled to an eutrophication model. The models were used together with a methodology for loads estimation to foster the understanding of such processes in the largest reservoir in Western Europe—the Alqueva. Nutrient enrichment and eutrophication are water quality concerns in this man-made impoundment. A total phosphorus and nitrogen loads quantification methodology was developed to estimate the inputs in the reservoir, using point and non-point source data.Field data (including water temperature, wind, water elevation, chlorophyll-a, nutrient concentration and dissolved oxygen) and estimated loads were used as forcing for simulations.The analysis of the modeling results shows that spatial and temporal distributions for water temperature, chlorophyll-a, dissolved oxygen and nutrients are consistent with measured in situ data.Modeling results allowed the identification of likely key impact factors on the water quality of the Alqueva reservoir. It is shown that the particular geomorphological and hydrological characteristics of the reservoir together with local climate features are responsible for the existence of distinct ecological regions within the reservoir.     

遥感水文耦合模型的研究进展

遥感水文的耦合模型在目前生态环境领域,特别是在水资源的应用和管理中其作用日益重要,具有大流域尺度上快速应用、实时动态监测等优点。结合国内外近年来取得的研究成果,文章综述了遥感水文耦合模型的研究进展。首先介绍了遥感技术在水文学中的应用,讨论了它的分类发展概况,接着介绍了几种主要的遥感水文耦合模型及其应用实例,包括SCS(SoilConservationServices)模型、SiB2(SimpleBiosphereModelversion2)简化生物圈模型、SRM(SnowmeltRunoffModel)融雪径流模型以及SWAT(SoilandWaterAssessmentTool)模型,最后展望了遥感水文耦合模型未来的发展趋势,指出尺度问题上的时空变异性仍是其发展的关键,与GIS(Geographicinformationsystem)及其他空间技术的相结合是其未来发展的重要方向,从而为水文学、水资源的预测评价等研究提供参考。     

Esteros del Ibera: hydrometeorological and hydrological characterization

The objective of this work is to analyze at a regional scale the hydrometeorological and hydrological characteristics of the Esteros del Ibera, a vast freshwater wetland located in NE Argentina. Since water is the main driving force in the inland wetlands and variations in water level impose conditions on the behavior of vegetation and animal populations, the knowledge of the main hydrometeorological variables that affect the hydrology is essential. Data correlation analysis makes it possible to evaluate the observed changes in the wetland and to infer its response to regional climatic change. As a first approach, the construction of a topo-bathymetric map provides a basic tool for developing a digital elevation model (DEM) using a geographic information system (GIS) and models that are based on a spatial scale.     

Sensitivity of the SWAT model to the soil and land use data parametrisation: a case study in the Thyle catchment,Belgium

The sensitivity of the distributed hydrological SWAT model to the pre-processing of soil and land use data was tested for modelling rainfall-runoff processes in the Thyle catchment in Belgium. To analyse this sensitivity, 32 different soil and land use parameterisation scheme were generated and evaluated. The soil input data sources were a generalised soil association map at a scale of 1:500,000, a detailed soil map at a scale of 1:25,000 and the soil profile analytical database AARDEWERK. These soil data were combined with a detailed and a generalised land use map. The results suggest that the SWAT model is extremely sensitive to the quality of the soil and land use data and the adopted pre-processing procedures of the geographically distributed data. The resolution and fragmentation of the original map objects are significantly affected by the internal aggregation procedures of the SWAT model. The catchment size threshold value (CSTV) is thereby a key parameter controlling the internal aggregation procedure in the model. It is shown that a parabolic function characterises the relationship between the CSTV and the hydrological modelling performance of the uncalibrated model, suggesting that optimal uncalibrated modelling results are not obtained when the CSTV is minimised. The hydrological response of the SWAT model to the calculated soil properties is significant. Therefore preference should be given to the calculation of the derived hydrologic soil properties prior to averaging of the profile data. Finally some general guidelines are suggested for parameterising soil and land use in the SWAT model application.     

Analyse „stetigkeitsbasierter“ Methoden zur Bestimmung von Stofffrachten in Fließgewässern

Aim and background

Increasing ecological awareness puts the load as a tool for water quality assessment in the foreground. Therefore it is very desirable to find optimal procedures for any given situation on basis of existing data. Criteria will be derived to fill that desire.

Method

The load for a water ingredient is an integrated entity of time-continuous loads (product of concentration and flow) for a given time, i.?e. a year (yearly load). Normally you can only observe a sample (in a statistical meaning) of these data. Therefore, load calculations vary with the concrete sample given. Each such calculation represents an estimation of the load, afflicted with some uncertainty. This uncertainty can be quantified, at least approximatively, by adding variance (scatter around “expected” mean) and the square of bias (divergence of “expected” mean from true mean). This quantity is called “mean squared error”. The methodological results will be illustrated by examples.

Focus

The main focus lies on the methodologies, which, besides data of concentrations observed discretely in time, additionally use quasi-continuously recorded data of other variates, namely the flow. For that situation, statistical models are developed and the load derived and estimated according to existing data. Hereby it is seen that all model based estimation formulae can be described as standard sampling formulae plus some additional terms which stem from comparison of some measurements (i.?e. mean) for quasi-continuous and discrete samples. This way a “continuity-correction” is performed on the standard formulae for the sampling case. This method is called “continuity-based” load determination.

Results

A surprising result is that no complicated mathematical-statistical models are necessary to determine the load. A simple linear concentration- or load-flow-model is sufficient. Additional variates lead, most of the time, to a larger mean squared error in load estimation, even when it is well known that they cannot detoriate the model fit. Only models which describe the concentration extraordinarily precise, near perfection, result in a smaller error.

Implications

It is enough to use one of the given formulae with some “continuity correction” to calculate a load. That can be done without using any software.     

Risk-based modelling of diffuse land use impacts from rural landscapes upon salmonid fry abundance

Research has demonstrated that landscape or watershed scale processes can influence instream aquatic ecosystems, in terms of the impacts of delivery of fine sediment, solutes and organic matter. Testing such impacts upon populations of organisms (i.e. at the catchment scale) has not proven straightforward and differences have emerged in the conclusions reached. This is: (1) partly because different studies have focused upon different scales of enquiry; but also (2) because the emphasis upon upstream land cover has rarely addressed the extent to which such land covers are hydrologically connected, and hence able to deliver diffuse pollution, to the drainage network. However, there is a third issue. In order to develop suitable hydrological models, we need to conceptualise the process cascade. To do this, we need to know what matters to the organism being impacted by the hydrological system, such that we can identify which processes need to be modelled. Acquiring such knowledge is not easy, especially for organisms like fish that might occupy very different locations in the river over relatively short periods of time. However, and inevitably, hydrological modellers have started by building up piecemeal the aspects of the problem that we think matter to fish. Herein, we report two developments: (a) for the case of sediment associated diffuse pollution from agriculture, a risk-based modelling framework, SCIMAP, has been developed, which is distinct because it has an explicit focus upon hydrological connectivity; and (b) we use spatially distributed ecological data to infer the processes and the associated process parameters that matter to salmonid fry. We apply the model to spatially distributed salmon and fry data from the River Eden, Cumbria, England. The analysis shows, quite surprisingly, that arable land covers are relatively unimportant as drivers of fry abundance. What matters most is intensive pasture, a land cover that could be associated with a number of stressors on salmonid fry (e.g. pesticides, fine sediment) and which allows us to identify a series of risky field locations, where this land cover is readily connected to the river system by overland flow.     

Eco-hydrological modelling in a highly regulated lowland catchment to find measures for improving water quality

Water quality modelling in the meso-scale Rhin catchment in the German federal state Brandenburg was done (1) to answer some specific questions concerning identification of point and diffuse sources of nutrient pollution in the catchment, (2) to assess the influences of possible climate and land use changes on water quantity and quality and (3) to evaluate potential measures to be done in order to achieve a “good ecological status” of the river and its lakes as required by the Water Framework Directive (WFD).The Rhin catchment is a typical highly regulated lowland river basin in Northern Germany. The regulations complicate water quantity and quality modelling in the catchment. The research was done by using the eco-hydrological model SWIM (Soil and Water Integrated Model), which simulates water and nutrient fluxes in soil and vegetation, as well as transport of water and nutrients to and within the river network. The modelling period was from 1981 until 2005. After calibrating the hydrological processes at different gauges within the basin with satisfactory results, water quality (nitrogen and phosphorus) modelling was done taking into account the emissions of different point sources (sewage treatment plants, etc.) and identifying the amount of diffuse pollution caused mainly by agriculture.For suggesting some feasible measures to improve water quality and to reduce diffuse pollution considering possible climate and land use changes, different reasonable scenarios were applied in consultation with the Environmental Agency of Brandenburg (LUA). The study revealed that the amount of water discharge has significant influence on the concentration of nutrients in the river network, and that nitrogen pollution, caused mainly by diffuse sources, could be notably reduced by application of agricultural measures, whereas the pollution by phosphorus could be diminished most effectively by the reduction of point source emissions.     

Multiple-pattern parameter identification and uncertainty analysis approach for water quality modeling

This paper presents a multiple-pattern parameter identification and uncertainty analysis approach for robust water quality modeling using a neural network (NN) embedded genetic algorithm (GA). The modeling approach uses an adaptive NN–GA framework to inversely solve the governing equations in a water quality model for multiple parameter patterns, along with an alternating fitness method to maintain solution diversity. The procedure was demonstrated through a coupled 2D hydrodynamic and eutrophication model for Loch Raven Reservoir in Maryland. The inverse problem was formulated as a nonlinear optimization problem minimizing the degree of misfit (DOM) between model results and observed data. A set of NN models was developed to approximate the input-output response relationship of the Loch Raven Reservoir model and was incorporated into a GA framework in an adaptive fashion to search for near-optimal solutions minimizing the DOM. The numerical example showed that the adaptive NN–GA approach is capable of identifying multiple parameter patterns that reproduce the observed data equally well. The resulting parameter patterns were incorporated into the numerical model, and a multiple-pattern robust water quality modeling analysis, along with a compound margin of safety (CMOS) method, was proposed and applied to analyze the parameter pattern uncertainty.     

Application of various mathematical models to data from the uptake of methyl mercury in bluegill sunfish (Lepomis macrochirus)

Evaluated and compared are the results of various mathematical models to data from the uptake of methyl mercury in bluegill sunfish (Lepomis macrochirus). Data were obtained from the direct uptake of methyl mercury from water in bluegill at 9°C and at a CH₃HgCl concentration of 0.2 ppb. The models considered are: (1) linear uptake relationship; (2) first-order kinetics, one-compartment or single-exponential model; (3) combination of first-order kinetics and the linear uptake relationship, designated as slope-exponential model; (4) two-compartment or double-exponential model; (5) three-compartment model, including a storage compartment for the build up of contaminant, designated as storage model; (6) three-compartment model, allowing two routes of elimination, designated the “Y” model; (7) an empirical uptake relationship having the form of a rectangular hyperbola.A comparison of the nonlinear models showed that the empirical model had fewer convergence problems in obtaining parameter estimates and its parameter values had less variation. The best fit was made by the “Y” model, the empirical model gave one of the smaller values of the residual mean squares, and other nonlinear models had computational convergence difficulties. The lack of computational problems and the comparitively small residual mean squares resulted in the selection of and the preference for the empirical model for use in describing the individual and interactive effects of temperature and methyl mercury concentration on the direct uptake of methyl mercury from water by bluegill.     

Futurecoast: Predicting the future coastal evolution of England and Wales

Analysis of shoreline change is often based exclusively upon the littoral cell concept and modelling of hydrodynamic processes. The Futurecoast study has considered fresh approaches to assessing shoreline evolution, which have been used to provide an analysis of future long-term evolution for the entire shoreline of England and Wales. This has been based upon an improved understanding of coastal systems and their behavioural characteristics. The study has included a range of supporting studies, focussing upon maximizing use of existing information and experience. A number of additional data sets have also been produced. The integration of leading expertise from different areas of coastal research to collectively consider this information has been the foundation for the study. The key outputs from this research are: (1) Improved understanding of coastal behaviour; (2) Assessment of future shoreline evolution; (3) Supporting information and data; (4) Delivery of results on an interactive CD-ROM.     

Trophic food web and ecosystem attributes of a water reservoir of the Ria Formosa (south Portugal)

Using a top-down modelling approach, a balanced trophic food web model of a water reservoir of the Ria Formosa lagoonal system was constructed. Few adjustments of input data were necessary to run the model since most of the parameters were estimated at the study site and the characteristics of the water reservoir allowed a high degree of control and precision in terms of sampling and data collection. Trophic levels of the 14 compartments included in the model varied between 1.0 for primary producers and detritus to 3.4 for carnivorous fish and the 14 groups were aggregated in a food chain with six trophic levels. The water reservoir has a detritus based food chain, with the majority of the biomass concentrated in the first two levels, the producers level and the herbivore/detritivore level (97.6%). The transfer efficiencies were low, and decreased with increasing level number, varying between 6.0 and 0.2%. The degree of “ecosystem maturity” was difficult to establish, but several parameters indicate that it could be high. The water reservoir studied, which has similar environmental and ecological characteristics as the Ria Formosa lagoon, is near its carrying capacity.