Assessment of nitrogen leaching from arable land in large river basins: Part I. Simulation experiments using a process-based model

A two-step procedure for analysing nitrogen leaching from arable land in large river basins is suggested: (1) application of a process-based dynamic model for a set of representative conditions in a large river basin to simulate water and nitrogen fluxes and (2) development of a fuzzy-rule based metamodel using the simulated nitrogen fluxes in Step 1 as a training set. After that the metamodel can be used for rapid assessment of water quality inside the considered ranges of parameters, describing natural conditions and management practices. This paper describes Step 1 of the procedure. Step 2 is described in an accompanying paper (Haberlandt et al., Ecological Modelling 150 (3) (2002) 277–294). The advantage of this approach is that it combines the ‘process-based foundation’ with the resulting simplicity of the metamodel. Simulation experiments for analysing nitrogen (N) leaching from arable land were performed using the Soil and Water Integrated Model (SWIM) for a set of representative conditions in the Saale basin (23 687 km²) in Central Europe. The Saale River is one of the main tributaries of the Elbe. In advance, hydrological validation of the model was done for the whole Saale basin and validation of nitrogen dynamics was fulfilled in two mesoscale sub-basins of the Elbe. For the simulation experiments the drainage basin area was sub-divided into five climate zones and nine representative soil classes were chosen. The basic rotation and fertilisation schemes were established using regional information obtained from literature. In addition, the effects of changing the basic rotation to more/less intensive ones and changing fertilisation rates by 50% increase/decrease were studied. The ranges of simulated nitrogen fluxes for the basic rotation and fertilisation schemes are comparable to available regional estimates and differences between sub-regions and soils are plausible. The relative importance of natural and anthropogenic factors affecting nitrogen leaching for the Saale River basin was as follows: (1) soil, (2) climate, (3) fertilisation rate and (4) crop rotation. The simulation experiments provide a basis for a fuzzy-rule based metamodel approach, which aims at rapid water quality assessment of large regions.     

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.     

Integrating wetlands and riparian zones in river basin modelling

Wetlands, and in particular riparian wetlands, represent an interface between the catchment area and the aquatic environment. They control the exchange of water and related chemical fluxes from the upper catchment area to surface waters like streams and lakes. Their influence on water and nutrient balances has been investigated mainly at the patch scale. In this study an attempt was made (a) to integrate riparian zones and wetlands into eco-hydrological river basin modelling, and (b) to quantify the impacts of riparian wetland processes on water and nutrient fluxes in a meso-scale catchment located in the northeastern German lowland. The investigation was performed by analysing hydro-chemical field data and applying the eco-hydrological model SWIM (Soil and Water Integrated Model), which was extended to reproduce the relevant water and nutrient flows and retention processes at the catchment scale in general, and in riparian zones and wetlands in particular. The main extensions introduced in the model were: (1) implementation of daily groundwater table dynamics at the hydrotope level, (2) implementation of water and nutrient uptake by plants from groundwater in riparian zones and wetlands, and (3) assessment of nutrient retention in groundwater and interflow. The simulation results indicate that wetlands, though they represent relatively small parts of the total catchment area, may have a significant impact on the overall water and nutrient balances of the catchment. The uncertainty of the simulation results is considerably high, with the main sources of uncertainty being the model parameters representing the geo-hydrology and the input data for land use management.     

Perspectives on small watershed management in China: the case of Biliu

River basin management in China has focused on large rivers, such as the Yangtze and Yellow Rivers. However, there are also about 20,000 small river basins that deserve attention. The Biliu River basin in Liaoning Province, northeast China, which is 156 km in length, has many features common to small river basins, including divided jurisdiction among governments leading to vertical and horizontal fragmentation. In the Biliu basin, the key municipalities are Dalian with a population of almost 6 million people and Yingkou with about 2.28 million people. Each has different interests and needs, making coordination and collaboration difficult. The literature and practice suggest that effective integrated water resource management (IWRM) requires at least six features: (1) vision, policy and strategy; (2) a legislative or statutory basis to provide credibility and authority; (3) a river basin organization to coordinate development and management; (4) specification of functions and authority of the river basin organization; (5) public participation and community involvement; and (6) an IRWM strategy and plan. Water management in the Biliu River basin is assessed relative to these features of IWRM, with recommendations offered regarding changes to have water management in the Biliu River basin to reflect what is expected in an IWRM approach.     

An integrated river basin-coast-sea modelling scenario for nitrogen management in coastal waters

Linked river basin and coastal water models were applied to analyse the effects of an optimal nitrogen management scenario in the Oder/Odra river basin on water quality in the Oder (Szczecin) Lagoon and the Pomeranian Bay (Baltic Sea). This scenario would reduce nitrogen loads into the coastal waters by about 35%, a level which is similar to the load of the late 1960’s. During summer the primary production and algae biomass in the Oder estuary is limited by nitrogen, which makes a nitrogen management reasonable. The comparison of the late 1960’s and the mid 1990’s shows that an optimal nitrogen management has positive effects on coastal water quality and algae biomass. However, this realistic nitrogen reduction scenario would not ensure a good coastal water quality according to the European Water Framework Directive. A good water quality in the river will not be sufficient to ensure a good water quality in the lagoon. Nitrogen load reductions bear the risk of increased potentially toxic, blue-green algae blooms, especially in the Baltic coastal sea. However, to reach water quality improvements in lagoons and inner coastal waters, nitrogen cuts are necessary. A mere focus on phosphorus is not sufficient.     

A comparison of the water management systems in France and China

This paper compares legal systems for water management in France and China, with a focus on integrated water resources management and regarding in particular the formulation of policies and their implementation. The research shows that China has committed itself to the efficient management of water resources through the development of various policy tools during the current period. This commitment, however, has often been interrupted and distorted by politics, resulting in the neglect of socioeconomic and environmental priorities. France has developed a legislative framework and practical instruments to apply integrated water resources management at the river basin level since the 1960s. This experience and the current implementation of the European Water Framework Directive brings elements that can contribute to Chinese society meeting its water challenges.     

MODELKEY

The EU Water Framework Directive (WFD) requires the achievement of good ecological and chemical status in European river basins. However, evidence is increasing that a majority of European water bodies will not achieve this goal. Nutrient emissions and related eutrophication together with hydromorphological alterations have been suggested as the major driving forces of this insufficient ecological status. MODELKEY (511237 GOCE, FP6) provides strong evidence that toxic chemicals also affect the ecological status of European rivers. This was demonstrated in the case study rivers Elbe, Scheldt and Llobregat on different scales. This paper summarises key findings of MODELKEY including recommendations for WFD implementation. We ? provide evidence of toxic stress in aquatic ecosystems, ? provide evidence that impairment of ecological status results from impact of multiple stressors, ? suggest a tiered approach to assess impact of chemicals on ecological status, ? suggest a new approach for deriving candidate compounds for monitoring and prioritisation, ? call for consideration of bioavailability and bioaccumulation in chemical status assessments, ? suggest improvements for WFD water quality monitoring programmes, ? provide new integrated tools for basin-scale risk assessment and decision making, ? developed a Decision Support System to support river basin management. These key results will be presented in a series of ten integrated sections; for the scientific details please refer to publications listed on the MODELKEY website (http://www.modelkey.org/). This article also looks beyond MODELKEY and proposes a combination of MODELKEY diagnostic tools with recent ecological methods to further improve effectiveness of river basin management.     

Assessing water quality in the Ceyhan River basin (Turkey) with the use of aquatic macrophytes

As a major biotic component of many lotic ecosystems, macrophytes consist a major component of running waters are often used as indicators within the European Water Framework Directive (WFD) to establish ecological quality. In this study, we investigated macrophyte community structure (e.g. composition, abundance and diversity) in Ceyhan River Basin located in the Southeastern Anatolian Region in Turkey. Data was collected during 2014–2015 from river sites located throughout the basin to evaluate the relationship between aquatic vegetation and river physico-chemical factors. The ecological status of the river basin was also calculated based on Macrophyte Biological Index for River (IBMR). In total, 33 macrophyta taxa were observed. According to their biological classification (life form), filamentous algae (FA), free floating (FF), floating leaved (FL) and submersed (S) macrophytes reached their maximum abundance value in summer, while emergent (E) macrophytes were at their maximum abundance in both summer and autumn. The ecological status of the Ceyhan River basin ranged from moderate to bad. The values found are reasonably comparable to IBMR scores recorded in rivers of other Mediterranean countries. IBMR index may be suitable to some extent to establish a basis for ecological quality assessment in Turkish River systems.     

Assessment of nitrogen leaching from arable land in large river basins: Part II: regionalisation using fuzzy rule based modelling

This study deals with fuzzy rule based modelling of nitrogen (N)-leaching from arable land. Main purpose is the elaboration of a method, which allows dynamical regionalisation of results from process-based models for large regions and can be efficiently included in metamodels or decision support systems for rapid integrated assessment of water resources. The paper is the second part of a two-part paper. In the first paper the distributed ecohydrological model SWIM had been applied to calculate and analyse nitrogen dynamics in arable soils for a set of representative natural and management conditions in the Saale River basin (Ecol. Model. (in press)). Here, in the second paper the results from those simulation experiments are used to define, train and validate fuzzy rule systems for the estimation of N-leaching. Nine fuzzy rule systems, specific for nine soil classes, were created from the simulation experiments, representing the conditions for the whole Saale River basin. The fuzzy rule systems operate on monthly time steps and consist of 15 rules and seven input variables each, which are compiled from time series of precipitation, percolation and evapotranspiration as well as from information about fertilizer and crop specific nitrogen uptake. Simulated annealing as a non-linear discrete optimisation method is used for automatic rule assessment. Validation of the fuzzy rule systems, carried out by split sampling of 30-year simulation period, shows satisfactory performance on an annual basis and good performance on the long-term basis with average correlation between SWIM-simulated and fuzzy rule-estimated N-leaching values of 0.78 and 0.94, respectively.     

A multi-scale approach to modelling spatial and dynamic ecological patterns for reservoir's water quality management

With growing levels of urbanization and agriculture throughout the world, it is increasingly important that both research and management efforts take into account the effects of this widespread landscape alteration and its consequences for natural systems. Freshwater ecosystems, namely reservoirs, are particularly sensitive to land use changes. In this context, modelling can be very useful, for decision support, as an investigative tool to forecast the outcome of various scenarios, to guide current management in order to meet future targets and to develop integrated frameworks for management accordingly to the Water Framework Directive (WFD). The present paper examined the applicability of a holistic Stochastic-Dynamic Methodology (StDM), coupled with a Cellular Automata (CA) model, in capturing how expected changes at land use level will alter the ecological status of lentic ecosystems, namely at physicochemical and biological levels. The methodology was applied to Portuguese reservoirs located in the Douro's basin and illustrated with a series of stochastic-dynamic and spatial outputs taking into account expected scenarios regarding land use changes. Overall, the simulation results are encouraging since they seem to demonstrate the tool reliability in capturing the stochastic environmental dynamics of the selected metrics facing spatial explicit scenarios. The ultimate goal was to couple monitoring assessment and the described modelling techniques to ease management and decision making regarding the practical implementation of the WFD, both at the scale of the reservoir body and at the scale of the respective river watershed dynamics.     

黑河流域土地退化分类研究

黑河流域位于我国的西北内陆干旱区。人类不合理利用水资源造成的土地退化，已成为黑河流域一个非常严重的生态问题。土地荒漠化是该流域最典型和最严重的土地退化形式。对该流域土地退化的空间分布、特点、退化面积等方面还没有较为详细的研究，因此探讨这个问题就显得非常重要。文章通过最新的遥感影像资料(2000年)，在分析已有的研究成果的基础上，结合野外调查，利用遥感和地理信息系统(GIS)技术，初步分析了黑河流域土地退化的情况。研究结果表明，黑河流域土地退化主要有5种类型，即：水土流失、干旱化、植被退化、盐渍化和沙漠化。土地退化面积达29971．91km^2，占整个流域面积的23．06％；其中，水土流失主要分布在祁连山的南部山区，面积为5747．68km^2，占整个流域土地退化面积的19．18％，主要是由于过度开垦和放牧造成的；由于人类活动的影响，造成水资源在时空上的重新分配而导致的干旱化土地主要分布在山前部分冲、洪积平原的河流沿岸附近，其面积为1369.96km^2，占整个流域土地退化面积的4．57％；盐渍化土地是该流域土地退化的主要类型之一，面积为10591．82km^2，占整个流域土地退化面积的35．34％，分布在流域的低地、冲积扇的边缘等位置，主要是由于干旱的气候条件造成的；沙化土地，包括流动沙丘(地)，是研究区土地退化面积最大的类型，为10771．97km^2，占整个流域土地退化面积的35.94％，这其中也包括历史时期形成的沙漠和现代形成的大部分沙地；植被退化土地面积为1490．48km^2，只占整个流域土地退化面积的4．97％。通过分析可知，黑河流域土地退化严重，特别是在下游地区。人类不合理的经济活动，尤其是对该流域内有限水资源的不合理利用，是导致该地区土地生态系统脆弱的主要因素。     

Integrated river basin management in rapidly urbanizing areas: a case of Shenzhen, China

The rapid urbanization of China is causing a burden on their water resources and hindering their sustainable development. This paper analyzes effective methods to integrated river basin management (IRBM) using Longgang River basin of Shenzhen as an example, which is the city with the fastest rate of urbanization in China and even the whole world. Over the past 20 years, China has undergone a population boom due to the increase of immigrant workers and rapid development of laborintensive industries, which led to the sharp increase of water consumption and sewage discharge. However, the construction of the water infrastructure is still lagging far behind the environmental and social development, with only 32.7% of sewage in the district being treated. Currently, every water quality indicator of the Longgang River basin was unable to meet the required corresponding environmental standards, which further aggravated the water shortages of the region. Thus, an analytical framework is proposed to address the IRBM of the study area. The problems with the current management system include the lack of decentralization in decision-making, lack of enforcement with redundant plans, weak management capacity, financial inadequacy, and a poor system of stakeholder participation. In light of the principles of IRBM and the situation of the region, corresponding measures are put forward, including an increase of power given to sub-district offices, fewer but more feasible plans, capacity building among stakeholders, a combination of planning and marketing for overcoming financial inadequacy, and profound reform in the public participation system. The framework and institutional suggestions could inform similar processes in other representative river basins.     

特定小流域水质模型的选择

根据特定小流域的水文特点和实际要求，建立一个流域综合水质模型，它由三个子模型支持，即：河流水质模型、水库富养营化模型和非点源污染模型。本工作对河流水质模型（ＱＵＡＬ２ＥＵ）加以改进，使之适应Ｗ河的具体情况，并在ＱＵＡＬ２ＥＵ增加了模拟ＣＯＤ、网箱养鱼和底泥泛起的功能。完成了作了水源地的水库地的水库富营养化模型，解决了流域内农业耕作、污水灌溉等造成的非点源污染随降雨径流进入水体过程的模拟和计算，使之     

Classification of coastal waters according to the new Italian water legislation and comparison with the European Water Directive

New legislation for the protection of inland surface waters, transitional waters, coastal waters and ground waters has recently been established in Italy. This law presents a new integrated approach, where all water bodies are considered as complex ecosystems to be studied in each of their components. The new concept of environmental quality of the water body, based on the ecological and chemical status, is also introduced. At the same time (i.e. the end of 2000), the European Community approved the European Water Framework Directive based on the same basic environmental concepts and criteria of the new Italian law. This paper analyses the important points and innovations required by the new Italian legislation for monitoring and classification of marine coastal waters. Details of definitions, parameters, analysis and monitoring programs are discussed. A comparison with the European Water Framework Directive is eventually given, underlining the specific characteristics of the Mediterranean sea, which have to be taken into consideration when applying the European Directive to this particular ecoregion.     

黄河"断流”对该河段河水中主要离子化学特征的影响

根据全球水质监测计划（GEMS/WaterProgram)和我国水利部黄河流域的水质监测数据,对1970s-1990s期间黄河下游河水主要离子含量的变化趋势及其与“断流”现象之间的关系进行了研究,结果表明,近年来黄河下游“断流现象”的频频出现,主要与枯水期中、上游地区引水量急剧增加有关;黄河的“水质浓化”趋势也主要由中、上游地区大量引水灌溉农田引起,因此,黄河“断流”与“水质浓化”现象是同一人类活动的两个平行的生态后果。     

洮儿河流域农业生态地质环境研究

系统分析了吉林西部洮儿河流域的农业生态地质环境特征,揭示了流域内影响农业可持续发展的五大农业生态地质环境问题;按照地质、地貌、自然资源状况、生态环境灾害、环境质量等综合要素对流域进行了环境分区;最后论述了流域内农业生态地质环境的演化过程和影响因素。     

Flux-based risk management strategy of groundwater pollutions: the CMF approach

A site- and receptor-specific risk management strategy for groundwater pollution based on the measurement of contaminant mass flux is proposed. The approach is useful and compatible with the demands formulated in the European Water Framework Directive, its Groundwater Daughter Directive and the regulations applicable in the EU member states. The proposed CMF method focuses on the following: (1) capture zones, (2) the location of control planes, (3) the definition of the maximum allowed contaminant mass discharge and (4) contaminant mass flux measurements. For every control plane, such a maximum allowed contaminant mass discharge is derived and is crucial for the receptor risk management strategy. The method is demonstrated for a large area of groundwater pollution present in the industrial area of Vilvoorde–Machelen located in Flanders, Belgium.     

Ecological modelling of nitrate pollution in small river basins by spreadsheets and GIS

With the increasing importance and awareness of water quality in the small basins, the modelling system is developed for monitoring and predictions of surface water pollution. The compartment model deals with basin characteristics extended by land cover attributes. The parameters of the model are estimated by experimental data of water quality together with land cover types that serve as nutrient detention media or transformers. The study examines methodology to determine the potential areas of nitrate pollution from point and non-point sources by remote sensing techniques. Classification of water, agricultural, forest and urban areas is processed with satellite images (LANDSAT 7). Whereas the agricultural and urban areas act as sources of pollution, forest zones operate as sinks. The nitrate levels are decreased downstream, if the proportion of the forest inside contribution zones increases. The modelling system is used to simulate amounts of nitrates in each compartment of the stream during the monitored period of one year. The number of compartments and their lengths are estimated on the basis of morphology of the basin. Simulation of the dynamic model is carried out with the TabSim. Geographic information system (GIS) and remote sensing tools are used to manage and estimate nitrate inflows from point and non-point sources of pollution. The article presents the spatial and time variation of the nitrate (NO₃⁻) within the basin of the stream Rakovnický (the west part of Bohemia, the whole area of 368 km²). It is shown that the model approach extended by the GIS and remote sensing can support decision-making process for better management practices in the basins.     

Defining and modelling the coastal zone affected by the Po river (Italy)

One of the most important sources of pollution in coastal zones (CZ) is certainly that one produced by human activities in the associated river basin. Understanding the linkage between water quality in CZ and river catchments is important in order to better assess CZ processes and to evaluate different management options aimed at improving the coastal ecosystem state. CZ water quality targets as identified by the Water Framework Directive (EC 2000/60) require an accurate study of the effects of pollutant loads coming from river discharge.In order to evaluate the impacts of human activities in river catchments on the associated coastal zone, a sound definition for this geographic area is needed. Many definitions for this area have been proposed in different contexts. The definition is generally built upon a particular goal, and is henceforth highly variable according to the different purposes. In this paper a general methodology allowing to discern those areas of the sea that are directly influenced by fluvial discharge is presented. The methodology is based on the variation pattern of sea water characteristics, and provides a numerical evaluation of this influence. In particular an analysis based on salinity as tracer, results in a sound definition of this area. The methodology has been applied on the case study of the Po river. Due to the significant nutrient loads discharged by the river, the CZ associated with Po is affected by severe eutrophication phenomena that have important consequences on the ecosystem and on the socio-economy of the area.In order to study the impacts of nutrients loads carried by the river, a water quality model (WASP6) has been implemented. The model simulates the seasonal variability of nutrient concentrations, phytoplankton biomass and dissolved oxygen. Using the CZ model is possible to compare the effects of variations of nutrient loads on the biochemical (short term) and ecological (long term) quality of the coastal environment. This is accomplished by feeding nutrients loads forecasted for different scenarios by the catchment model (MONERIS) as forcing functions to the CZ model. This way the effect of the different catchment management scenarios are propagated to the CZ model, and the trophic conditions of the coastal ecosystem evaluated using TRIX.This study has been developed in the context of the European project EUROCAT.