A multi-scale framework for strategic management of diffuse pollution

A multi-scale framework for decision support is presented that uses a combination of experiments, models, communication, education and decision support tools to arrive at a realistic strategy to minimise diffuse pollution. Effective partnerships between researchers and stakeholders play a key part in successful implementation of this strategy. The Decision Support Matrix (DSM) is introduced as a set of visualisations that can be used at all scales, both to inform decision making and as a communication tool in stakeholder workshops. A demonstration farm is presented and one of its fields is taken as a case study. Hydrological and nutrient flow path models are used for event based simulation (TOPCAT), catchment scale modelling (INCA) and field scale flow visualisation (TopManage). One of the DSMs; The Phosphorus Export Risk Matrix (PERM) is discussed in detail. The PERM was developed iteratively as a point of discussion in stakeholder workshops, as a decision support and education tool. The resulting interactive PERM contains a set of questions and proposed remediation measures that reflect both expert and local knowledge. Education and visualisation tools such as GIS, risk indicators, TopManage and the PERM are found to be invaluable in communicating improved farming practice to stakeholders. (C) 2008 Elsevier Ltd. All rights reserved.

Evaluation of field wetlands for mitigation of diffuse pollution from agriculture: sediment retention, cost and effectiveness

Diffuse pollution, and the contribution from agriculture in particular, has become increasingly important as pollution from point sources has been addressed by wastewater treatment. Land management approaches, such as construction of field wetlands, provide one group of mitigation options available to farmers. Although field wetlands are widely used for diffuse pollution control in temperate environments worldwide, there is a shortage of evidence for the effectiveness and viability of these mitigation options in the UK. The Mitigation Options for Phosphorus and Sediment Project aims to make recommendations regarding the design and effectiveness of field wetlands for diffuse pollution control in UK landscapes. Ten wetlands have been built on four farms in Cumbria and Leicestershire. This paper focuses on sediment retention within the wetlands, estimated from annual sediment surveys in the first two years, and discusses establishment costs. It is clear that the wetlands are effective in trapping a substantial amount of sediment. Estimates of annual sediment retention suggest higher trapping rates at sandy sites (0.5–6 t ha�1 yr�1), compared to silty sites (0.02–0.4 t ha�1 yr�1) and clay sites (0.01–0.07 t ha�1 yr�1). Establishment costs for the wetlands ranged from £280 to £3100 and depended more on site specific factors, such as fencing and gateways on livestock farms, rather than on wetland size or design. Wetlands with lower trapping rates would also have lower maintenance costs, as dredging would be required less frequently. The results indicate that field wetlands show promise for inclusion in agri-environment schemes, particularly if capital payments can be provided for establishment, to encourage uptake of these multi-functional features.

First flush analysis in urban catchments

The effectiveness of structural elements employed for stormwater mitigation such as bioretention basins and constructed wetlands depend on the compatibility between their design specifications and actual stormwater quality and quantity characteristics. These structural elements are commonly designed to accommodate the initial portion of runoff considering the occurrence of first flush. Therefore, the effectiveness of stormwater quality treatment primarily depends on the in-depth knowledge of the first flush phenomenon and the ability to provide appropriate treatment. The current scientific knowledge relating to first flush is limited primarily due to research investigations being undertaken based on lumped rainfall and runoff parameters. This paper presents the outcomes of an in-depth study undertaken of the first flush phenomenon using a set of indicators which are not only innovative, but is also able to accurately represent the characteristics of the different sectors in a runoff hydrograph. The analysis undertaken confirmed that pollutant wash-off during the initial 10% of runoff volume was critical for the occurrence of first flush. Typically first flush was found to last up to 40% of the runoff volume. The study outcomes provide new knowledge to enhance the effectiveness of structural stormwater treatment measures.

Selecting rainfall events for effective Water Sensitive Urban Design (WSUD) implementation

The current approach for protecting the receiving water environment from urban stormwater pollution is the adoption of structural measures commonly referred to as Water Sensitive Urban Design (WSUD). The treatment efficiency of WSUD measures closely depends on the design of the specific treatment units. As stormwater quality can be influenced by rainfall characteristics, the selection of appropriate rainfall events for treatment design is essential to ensure the effectiveness of WSUD systems. Based on extensive field investigation of four urban residential catchments and computer modelling, this paper details a technically robust approach for the selection of rainfall events for stormwater treatment design using a three-component model. The modelling outcomes indicate that selecting smaller average recurrence interval (ARI) events with high intensity-short duration as the threshold for the treatment system design is the most feasible since these events cumulatively generate a major portion of the annual pollutant load compared to the other types of rainfall events, despite producing a relatively smaller runoff volume. This implies that designs based on small and more frequent rainfall events rather than larger rainfall events would be appropriate in the context of efficiency in treatment performance, cost-effectiveness and possible savings in land area needed.

The application of methods of ecosystem analysis to the evaluation of water quality

Guided by experience and the theoretical development of hydrobiology, it can be considered that the main aim of water quality control should be the establishment of the rates of the self-purification process of water bodies which are capable of maintaining communities in a state of dynamic balance without changing the integrity of the ecosystem. Hence, general approaches in the elaboration of methods for hydrobiological control are based on the following principles: a. the balance of matter and energy in water bodies; b. the integrity of the ecosystem structure and of its separate components at all levels. Ecosystem analysis makes possible a revelation of the whole totality of factors which determine the anthropogenic evolution of a water body. This is necessary for the study of long-term changes in water bodies. The principles of ecosystem analysis of water bodies, together with the creation of their mathematical models, are important because, in future, with the transition of water demanding production into closed cycles of water supply, changes in water bodies will arise in the main through the influence of 'diffuse' pollution (from the atmosphere, with utilisation in transport etc.).

Cheshire Meres 1994 November surveys

This is the Cheshire Meres 1994 November surveys report produced by the National Rivers Authority in 1995. The report focuses on some of Cheshire meres, which were showing evidence of increasing eutrophication, commonly due to anthropogenic inputs. Concern for the deterioration of the water quality of still waters has been translated by incorporating these priorities into the NRA North West Regional Environmental Strategy for Stillwaters. The meres were also being investigated as possible polluted waters under the EC Nitrate Directive. The ultimate aim is to formulate lakes management options in order to help preserve North West still waters and minimise future restoration programmes. For such pro-active work to be carried out, sufficient background data must be available. It should then be possible to fully assess the current status of these lakes, identify seasonal trends and detect significant point/diffuse pollution inputs. These surveys were the first of a series, and it was intended to repeat similar surveys in Summer and Autumn 1995, and include a further 20 meres.

Hydrological modelling of Maranhão and Pracana Basins, a first approach

Modelling the hydrology of hydrographic basins has shown itself as a useful tool in environment management. The hydrological models can be used for multiple purposes: estimate runoff from sequences of rainfall, access stream water quality, quantify the diffuse pollution that reaches water masses such as estuaries, rivers and lakes, etc. This study has as final objective to simulate and analyse the flow, sediment transport and water quality as a function of landuse and soil type in the basins of Maranhão and Pracana. The modelling system used is SWAT, Soil Water Assessment Tool. In this first phase of the study the hydrodynamic calibration of the model was performed using measurements of average daily flows in five stations. The model compares well with the measurements; the annual average flows are similar and the majority of the measured flow peaks coincide with the model peaks.

Water quality in lakes and reservoirs in China

Dissertation elaborated for the partial fulfilment of the requirements of the Master Degree in Civil Engineering in the Speciality Area of Hydarulics

Mitigation options for sediment and phosphorus loss from winter-sown arable crops

Sediment and P inputs to freshwaters from agriculture are a major problem in the United Kingdom (UK). This study investigated mitigation options for diffuse pollution losses from arable land. Field trials were undertaken at the hillslope scale over three winters at three UK sites with silt (Oxyaquic Hapludalf), sand (Udic Haplustept), and clay (Typic Haplaquept) soils. None of the mitigation treatments was effective in every year trialled, but each showed overall average reductions in losses. Over five site years, breaking up the compaction in tramlines (tractor wheel tracks) using a tine reduced losses of sediment and P to losses similar to those observed from areas without tramlines, with an average reduction in P loss of 1.06 kg TP ha(-1) Compared to traditional plowing, TP losses under minimum tillage were reduced by 0.30 kg TT ha(-1) over five site years, TP losses under contour cultivation were reduced by 0.30 kg TP ha(-1) over two site years, and TP losses using in-field barriers were reduced by 0.24 kg TP ha(-1) over two site years. In one site year, reductions in losses due to crop residue incorporation were nor significant. Each of the mitigation options trialled. is associated with a small cost at the farm-scale of up to 5 pound ha(-1), or with cost savings. The results indicate that each of the treatments his the potential to be a cost-effective mitigation option, but that tramline management is the most promising treatment, because tramlines dominate sediment and P transfer in surface runoff from arable hillslopes.

Hillslope scale surface runoff, sediment, and nutrient losses associated with tramline wheelings

Research on arable sandy loam and silty clay loam soils on 4° slopes in England has shown that tramlines (i.e. the unseeded wheeling areas used to facilitate spraying operations in cereal crops) can represent the most important pathway for phosphorus and sediment loss from moderately sloping fields. Detailed monitoring over the October–March period in winters 2005–2006 and 2006–2007 included event-based sampling of surface runoff, suspended and particulate sediment, and dissolved and particulate phosphorus from hillslope segments (each ∼300–800 m2) established in a randomized block design with four replicates of each treatment at each of two sites on lighter and heavier soils. Experimental treatments assessed losses from the cropped area without tramlines, and from the uncropped tramline area, and were compared to losses from tramlines which had been disrupted once in the autumn with a shallow tine. On the lighter soil, the effects of removal or shallow incorporation of straw residues was also determined. Research on both sandy and silty clay loam soils across two winters showed that tramline wheelings represented the dominant pathway for surface runoff and transport of sediment, phosphorus and nitrogen from cereal crops on moderate slopes. Results indicated 5·5–15·8% of rainfall lost as runoff, and losses of 0·8–2·9 kg TP ha−1 and 0·3–4·8 t ha−1 sediment in tramline treatments, compared to only 0·2–1·7% rainfall lost as runoff, and losses of 0·0–0·2 kg TP ha−1 and 0·003–0·3 t ha−1 sediment from treatments without tramlines or those where tramlines had been disrupted. The novel shallow disruption of tramline wheelings using a tine once following the autumn spray operation consistently and dramatically reduced (p < 0·001) surface runoff and loads of sediment, total nitrogen and total phosphorus to levels similar to those measured in cropped areas between tramlines. Results suggest that options for managing tramline wheelings warrant further refinement and evaluation with a view to incorporating them into spatially-targeted farm-level management planning using national or catchment-based agri-environment policy instruments aimed at reducing diffuse pollution from land to surface water systems. Copyright © 2010 John Wiley & Sons, Ltd.

Contributing understanding of mitigation options for phosphorus and sediment to a review of the efficacy of contemporary agricultural stewardship measures

Experiences from the Mitigation Options for Phosphorus and Sediment (MOPS) projects, which aim to determine the effectiveness of measures to reduce pollutant loading from agricultural land to surface waters, have been used to contribute to the findings of a recent paper (Kay et al., 2009, Agricultural Systems, 99, 67–75), which reviewed the efficacy of contemporary agricultural stewardship measures for ameliorating the water pollution problems of key concern to the UK water industry. MOPS1 is a recently completed 3-year research project on three different soil types in the UK, which focused on mitigation options for winter cereals. MOPS1 demonstrated that tramlines can be the major pathway for sediment and nutrient transfer from arable hillslopes, and that although minimum tillage, crop residue incorporation, contour cultivation, and beetle banks also have potential to be cost-effective mitigation options, tramline management is the one of the most promising treatments for mitigating diffuse pollution losses, as it was able to reduce sediment and nutrient losses by 72–99% in four out of five site years trialled. Using information from the MOPS projects, this paper builds on the findings of Kay et al. to provide an updated picture of the evidence available and the immediate needs for research in this area.

A framework for designing multi-functional cover crops

Cover crops are sown to provide a number of ecosystem services including nutrient management, mitigation of diffuse pollution, improving soil structure and organic matter content, weed suppression, nitrogen fixation and provision of resources for biodiversity. Although the decision to sow a cover crop may be driven by a desire to achieve just one of these objectives, the diversity of cover crops species and mixtures available means that there is potential to combine a number of ecosystem services within the same crop and growing season. Designing multi-functional cover crops would potentially help to reconcile the often conflicting agronomic and environmental agendas and contribute to the optimal use of land. We present a framework for integrating multiple ecosystem services delivered by cover crops that aims to design a mixture of species with complementary growth habit and functionality. The optimal number and identity of species will depend on the services included in the analysis, the functional space represented by the available species pool and the community dynamics of the crop in terms of dominance and co-existence. Experience from a project that applied the framework to fertility building leys in organic systems demonstrated its potential and emphasised the importance of the initial choice of species to include in the analysis

A influência da poluição difusa e do regime hidrológico peculiar do semiárido na qualidade da água de um reservatório tropical

In semiarid region of northeast Brazil, the majority of reservoirs used for public supply has suffered degradation of water quality affected by diffuse pollution from agricultural and livestock areas of the watershed and by hydrologic regime peculiar to the region, characterized by a rainy season with higher volumes stored in reservoirs and a dry season with a reduction in water level due to high evaporation and increase of eutrophication. The Dourado reservoir, located in Currais Novos city, semiarid region of Rio Grande do Norte state, is one example of a water supply reservoir that can have degradation of water quality and impracticability of their use, due to the high external input of nutrients from non-point sources of watershed during the rainy season and increasing of eutrophication due to decrease the stored volume during the dry period. This study aimed to investigate and quantify diffuse pollution and the hydrologic regime of semiarid region in order to establish standards regarding the water quality of Dourado reservoir. The study period was between the months of May 2011 to March 2012. The diffuse pollution was quantified in terms of watershed from the mass balance of phosphorus in the reservoir, as in relation to areas under different types of land use within the riparian zone of the reservoir from the assessment of soil chemical properties and losses of phosphorus in each area. The influence of hydrological regime on water quality of the reservoir was evaluated from the monthly monitoring of the morphometric, meteorological and limnological features throughout the study period. The results showed that the reservoir has received a high load of phosphorus coming from the drainage basin and presents itself as a system able to retain some of that load tributary, giving an upward trend of the eutrophication process. Diffuse pollution by nutrients from areas under different types of land use within the riparian zone of the reservoir was higher in areas under the influence of livestock, being this area considered a potential diffuse source of nutrients to the reservoir. Regarding the water regime during the rainy season the reservoir was characterized by high concentrations of nutrients and small algal biomass, while in the dry season the reduction of volume and increase of the water retention time of the reservoir, contributing to the excessive growth algal biomass, favoring an increase in eutrophication and deterioration of water quality. In synthesis the water quality of Dourado reservoir is directed by diffuse pollution coming from the drainage basin and the hydrological regime of the peculiar semiarid region, where the rainy season is characterized by high input of allochthonous compounds from the tributaries and erosion of the soil in the reservoir riparian zone, and the dry season characterized by reducing the storage volume due to high evaporation, high residence time of water and consequent degradation of water quality due to the increase of eutrophication process

Análise do uso e ocupação do solo das margens de um reservatório e a sua influência na qualidade da água

The building of water reservoirs has become a solution for water scarcity of the semiarid regions, however, the land use and occupation near the margins of the reservoirs have been causing serious damage to water quality, harming their use. This paper aims to analyze the land use and occupation in the margins of the Northeast reservoir and evaluate their influence on the water quality, to identify the areas and activities that represent an higher risk of contamination to the reservoir. The study was conducted at the reservoir Dourado, located in the city of Currais Novos - RN, during the period from August 2012 to February 2013. Were defined six areas regarding the land use and occupation, then, Water samples were collected from the margins in these areas for the characterization of water quality. The results showed that almost all Permanent Preservation Areas (PPA) from the reservoir is degraded, increasing the susceptibility of large input of nutrients and contaminants loads. The water reservoir showed low quality, being with strong evidence of eutrophication due to the nutrient accumulation arising from the activities surrounding the reservoir, mainly from agriculture and Livestock. The Areas 1 and 2 are the areas that present a greater risk of reservoir degradation, because are the possible major sources of nutrients (phosphorus total, orthophosphate and nitrate), however, due to the small size of the reservoir, any compound that reaches its margins ultimately affects the water quality of the same