Is water quality in British rivers "better than at any time since the end of the Industrial Revolution"?

We explore the oft-repeated claim that river water quality in Great Britain is "better now than at any time since the Industrial Revolution". We review available data and ancillary evidence for seven different categories of water pollutants: (i) biochemical oxygen demand (BOD) and ammonia; (ii) heavy metals; (iii) sewage-associated organic pollutants (including hormone-like substances, personal care product and pharmaceutical compounds); (iv) macronutrients (nitrogen and phosphorus); (v) pesticides; (vi) acid deposition and (vii) other variables, including natural organic matter and pathogenic micro-organisms. With a few exceptions, observed data are scarce before 1970. However, we can speculate about some of the major water quality pressures which have existed before that. Point-source pollutants are likely to have increased with population growth, increased connection rates to sewerage and industrialisation, although the increased provision of wastewater treatment during the 20th century will have mitigated this to some extent. From 1940 to the 1990s, pressures from nutrients and pesticides associated with agricultural intensification have increased in many areas. In parallel, there was an increase in synthetic organic compounds with a "down-the-drain" disposal pathway. The 1990s saw general reductions in mean concentrations of metals, BOD and ammonia (driven by the EU Urban Waste Water Treatment Directive), a levelling out of nitrate concentrations (driven by the EU Nitrate Directive), a decrease in phosphate loads from both point-and diffuse-sources and some recovery from catchment acidification. The current picture is mixed: water quality in many rivers downstream of urban centres has improved in sanitary terms but not with respect to emerging contaminants, while river quality in catchments with intensive agriculture is likely to remain worse now than before the 1960s. Water quality is still unacceptably poor in some water bodies. This is often a consequence of multiple stressors which need to be better-identified and prioritised to enable continued recovery.

Participatory scenario development for environmental management: a methodological framework illustrated with experience from the UK uplands.

A methodological framework is proposed for participatory scenario development on the basis of evidence from the literature, and is tested and refined through the development of scenarios for the future of UK uplands. The paper uses a review of previous work to justify a framework based around the following steps: i) define context and establish whether there is a basis for stakeholder engagement in scenario development; ii) systematically identify and represent relevant stakeholders in the process; iii) define clear objectives for scenario development with stakeholders including spatial and temporal boundaries; iv) select relevant participatory methods for scenario development, during initial scenario construction, evaluation and to support decision-making based on scenarios; and v) integrate local and scientific knowledge throughout the process. The application of this framework in case study research suggests that participatory scenario development has the potential to: i) make scenarios more relevant to stakeholder needs and priorities; ii) extend the range of scenarios developed; iii) develop more detailed and precise scenarios through the integration of local and scientific knowledge; and iv) move beyond scenario development to facilitate adaptation to future change. It is argued that participatory scenario development can empower stakeholders and lead to more consistent and robust scenarios that can help people prepare more effectively for future change.

Nitrate in United kingdom rivers: policy and its outcomes since 1970.

Modern conventional farming provides Western Europe and North America with reliable, high quality, and relatively cheap supplies of food and fiber, increasingly viewed as a potential source of fuel. One of the costs is continued widespread pollution of rivers and groundwater-predominantly by nutrients. In 1970, in both the United States and UK, farming was focused on maximizing yield and management practices were rapidly modernizing. Little attention was paid to the external impacts of farming. In 2010, diffuse pollution from agriculture is being seriously addressed by both voluntary and statutory means in an attempt to balance environmental costs with the continued benefits of agricultural production. In this paper we consider long-term changes in the concentration and flux of nitrate in five rural UK rivers to demonstrate the impact of agricultural intensification and subsequent policies to reduce diffuse pollution on river water quality between 1970 and 2010.

Long-term monitoring of river water nitrate: how much data do we need?

Long records of river water quality are invaluable for helping to understand the biogeochemistry of hydrological systems. They allow relationships to be established between changes in water quality (including seasonal cycles, episodic responses and long-term trends) and potential drivers, such as climatic forcing or human activity; they can act as a stimulus for process-oriented experimental research; they can be used to help to make predictions about future temporal and spatial patterns; and they can help to guide management options to mitigate water pollution. In this paper we present the case in favour of maintaining some long records of river water nitrate concentration at "benchmark" sites, in terms of enhancing process understanding and identifying system lags. Many long-term time series of nitrate concentration data share similar features including a pronounced seasonality characterised by a clear winter maximum, an upward trend in the post-war period followed by a levelling off, or even a decline in the last 20 years, and unusually high concentrations following drought years. Concentrations in any one year are often dependent on conditions in previous years; relationships can be established between concentrations and hydrological drivers (such as rainfall) with different lag periods which can yield information about supply or transport limitations to nitrate transfers. The interpretation of any record is dependent on its length: short records have a high potential for misinterpretation. Often, the value of long records only becomes apparent when analysed in retrospect, perhaps yielding insight into processes and phenomena for which the data collection programme was not originally designed. We, therefore, urge monitoring agencies to devise a strategy for maintaining long records--at least for a few benchmark stations.

The multi-annual carbon budget of a peat-covered catchment.

This study estimates the complete carbon budget of an 11.4 km(2) peat-covered catchment in Northern England. The budget considers both fluvial and gaseous carbon fluxes and includes estimates of particulate organic carbon (POC); dissolved organic carbon (DOC); excess dissolved CO(2); release of methane (CH(4)); net ecosystem respiration of CO(2); and uptake of CO(2) by primary productivity. All components except CH(4) were measured directly in the catchment and annual carbon budgets were calculated for the catchment between 1993 and 2005 using both extrapolation and interpolation methods. The study shows that: Over the 13 year study period the total carbon balance varied between a net sink of -20 to -91 Mg C/km(2)/yr. The biggest component of this budget is the uptake of carbon by primary productivity (-178 Mg C/km(2)/yr) and in most years the second largest component is the loss of DOC from the peat profile (+39 Mg C/km(2)/yr). Direct exchanges of C with the atmosphere average -89 Mg C/km(2)/yr in the catchment. Extrapolating the general findings of the carbon budget across all UK peatlands results in an approximate carbon balance of -1.2 Tg C/yr (+/-0.4 Pg C/yr) which is larger than previously reported values. Carbon budgets should always be reported with a clear statement of the techniques used and errors involved as this is significant when comparing results across studies.

Temporal and spatial analysis of nitrate concentrations from the Frome and Piddle catchments in Dorset (UK) for water years 1978 to 2007: evidence for nitrate breakthrough?

This paper analyses time series of nitrate concentration for 35 sites throughout the Frome and Piddle catchments in southern England for the period 1978--2007. The Piddle catchment lies wholly within the Chalk aquifer in its upper reaches, whereas the headwaters of the Frome are a mixture of Chalk and other lithologies; both rivers flow across Palaeogene sands and clays in their lower reaches, before discharging into Poole Harbour. At each site sources of observed variation arise from differences between sample month (seasonality) and year (underlying trend). Considering water year mean concentrations, there is a strong and highly significant positive correlation with year for all but two sites. The annual rate of increase tends to be higher in the Piddle than the Frome, and in both catchments the annual rate of increase tends to decrease downstream; both these effects relate to the degree of groundwater influence. In addition to the strong upward trend, there is also a clear seasonal cycle in nitrate concentration at most sites; amplitude generally increases downstream. Laying aside the assumption of linearity, solute breakthrough curves (S-curves) are fitted to 34 of the 36 nitrate time series. Results show that application of S-curves is an appropriate description of changes in annual mean concentrations over time and provides improvements over linear models in most cases. The interpretation of rising nitrate concentrations in these groundwater-dominated catchments moves from a statistical to a hydrological process base, providing valuable insight into lowland catchment function.

Intercomparison of Evapotranspiration Over the Savannah Volta Basin in West Africa Using Remote Sensing Data.

This paper compares evapotranspiration estimates from two complementary satellite sensors - NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and ESA's ENVISAT Advanced Along-Track Scanning Radiometer (AATSR) over the savannah area of the Volta basin in West Africa. This was achieved through solving for evapotranspiration on the basis of the regional energy balance equation, which was computationally-driven by the Surface Energy Balance Algorithm for Land algorithm (SEBAL). The results showed that both sensors are potentially good sources of evapotranspiration estimates over large heterogeneous landscapes. The MODIS sensor measured daily evapotranspiration reasonably well with a strong spatial correlation (R²=0.71) with Landsat ETM+ but underperformed with deviations up to ~2.0 mm day-1, when compared with local eddy correlation observations and the Penman-Monteith method mainly because of scale mismatch. The AATSR sensor produced much poorer correlations (R²=0.13) with Landsat ETM+ and conventional ET methods also because of differences in atmospheric correction and sensor calibration over land.

Impact of land drainage on peatland hydrology.

There is a long history of drainage of blanket peat but few studies of the long-term hydrological impact of drainage. This paper aims to test differences in runoff production processes between intact and drained blanket peat catchments and determine whether there have been any long-term changes in stream flow since drainage occurred. Hillslope runoff processes and stream discharge were measured in four blanket peat catchments. Two catchments were drained with open-cut ditches in the 1950s. Ditching originally resulted in shorter lag times and flashier storm hydrographs but no change in the annual catchment runoff efficiency. In the period between 2002 and 2004, the hydrographs in the drained catchments, while still flashy, were less sensitive to rainfall than in the 1950s and the runoff efficiency had significantly increased. Drains resulted in a distinctive spatial pattern of runoff production across the slopes. Overland flow was significantly lower in the drained catchments where throughflow was more dominant. In the intact peatlands, matrix throughflow produced by peat layers below 10 cm was rare and produced <1% of the runoff. However, in drained peatlands, matrix throughflow in deeper peat layers was common and provided around 23% of the runoff from gauged plots. Macropore flow, the density of soil piping, and pipeflow were significantly greater in drained peatlands than in intact basins. Gradual changes to peat structure could explain the long-term changes in river flow, which are in addition to those occurring in the immediate aftermath of peatland drainage.

Monitoring change in hydrological systems.

Monitoring is the process by which we keep the behaviour of the environment in view, providing essential information on how systems are changing and how fast, and allows us to learn to adjust what we are doing to get the best out of the system. This paper reviews the ways in which long-term study of the natural environment can be achieved. Three hydrological examples are then presented: nitrate leaching in a small agricultural catchment in south west England; the impact of drought on the peat-covered headwaters of the River Tees in northern England; and the impact of clear-felling on forest hydrology and nutrient export in the southern Appalachians. Monitoring programmes, if well designed and properly maintained, can provide important evidence of environmental change, revealing unexpected patterns and stimulating experimental research. The existence of long, reliable data sets considerably increases our ability to make informed decisions about the way in which we manage our river catchments.