Abstract
The need for improved abatement of agricultural diffuse water pollution represents cause for concern throughout the world. A critical aspect in the design of on-farm intervention programmes concerns the potential technical cost-effectiveness of packages of control measures. The European Union (EU) Water Framework Directive (WFD) calls for Programmes of Measures (PoMs) to protect freshwater environments and these comprise ‘basic’ (mandatory) and ‘supplementary’ (incentivised) options. Recent work has used measure review, elicitation of stakeholder attitudes and a process-based modelling framework to identify a new alternative set of ‘basic’ agricultural sector control measures for nutrient and sediment abatement across England. Following an initial scientific review of 708 measures, 90 were identified for further consideration at an industry workshop and 63 had industry support. Optimisation modelling was undertaken to identify a shortlist of measures using the Demonstration Test Catchments as sentinel agricultural landscapes. Optimisation selected 12 measures relevant to livestock or arable systems. Model simulations of 95% implementation of these 12 candidate ‘basic’ measures, in addition to business-as-usual, suggested reductions in the national agricultural nitrate load of 2.5%, whilst corresponding reductions in phosphorus and sediment were 11.9% and 5.6%, respectively. The total cost of applying the candidate ‘basic’ measures across the whole of England was estimated to be £450 million per annum, which is equivalent to £52 per hectare of agricultural land. This work contributed to a public consultation in 2016.
Highlights
There is considerable spatial variation in the reductions at WMC scale (Fig. 1), with reductions in nitrate ranging from under 1% in Eastern England to over 5% in North-Western England
Accounting for the uncertainty in the estimates of BAU measure uptake and, the gap to be closed with full implementation of the ‘basic’ (n = 12) measures, shows that the potential national impacts of the ‘basic’ measures could be approximately 1% higher or lower than the average estimate (Table 6)
Absolute changes in efficacy can be large where the average estimate of impact was large, but proportional changes are highest when predicted average reductions are lowest
Summary
Agricultural diffuse sources of pollution are recognised as the principal polluters of many rivers and lakes worldwide including those in the Baltic (Elofsson et al, 2003), Mediterranean (Panagopoulos et al, 2011), north America (Kramer et al, 2006), Europe (Lacroix et al, 2005; Crossman et al, 2013; Berger et al, 2017; Fischer et al, 2017; Mockler et al, 2017), Australia (Kroon, 2009; Thorburn, 2013; van Grieken et al, 2013; McDowell and Nash, 2013) and New Zealand (McDowell and Nash, 2013). The EU WFD integrates economic analysis into water policy for governing environmental management and Annex III explicitly calls for analysis of costs and effectiveness to support the design of Programmes of Measures (PoMs) to help achieve ‘good ecological status’ (WATECO, 2003; Baylis et al, 2008; Balana et al, 2011; Ghebremichael et al, 2013; van Grieken et al, 2013; Balana et al, 2015). Whilst research work delivers fundamental experimental evidence on the costs and effectiveness of individual control measures in specific settings, environmental status is assessed at coarser scale (e.g. water body scale) meaning that evidence is increasingly required on the scope for combined or integrated diffuse agricultural pollution control measures to help achieve policy targets (Bouraoui and Grizzetti, 2014). The complexities of pollution mobilisation, transfer and delivery through river catchments mean, that monitored outcomes will take years to decades to confirm successful impacts arising from targeted on-farm remediation (Kronvang et al, 2005; Meals et al, 2010; Collins et al, 2014; McGonigle et al, 2014; Wang et al, 2016)
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