Diffuse water pollution during recent extreme wet-weather in the UK: Environmental damage costs and insight into the future?

Y Zhang; S J Granger; M A Semenov; H R Upadhayay; A L Collins

doi:10.1016/j.jclepro.2022.130633

Diffuse water pollution during recent extreme wet-weather in the UK: Environmental damage costs and insight into the future?

J Clean Prod. 2022 Mar 1:338:130633. doi: 10.1016/j.jclepro.2022.130633.

Authors

Y Zhang¹, S J Granger¹, M A Semenov², H R Upadhayay¹, A L Collins¹

Affiliations

¹ Sustainable Agriculture Sciences, Rothamsted Research, North Wyke, Okehampton, EX20 2SB, UK.
² Plant Sciences Department, Rothamsted Research, West Common, Harpenden, AL5 2JQ, UK.

Abstract

Periods of extreme wet-weather elevate agricultural diffuse water pollutant loads and climate projections for the UK suggest wetter winters. Within this context, we monitored nitrate and suspended sediment loss using a field and landscape scale platform in SW England during the recent extreme wet-weather of 2019-2020. We compared the recent extreme wet-weather period to both the climatic baseline (1981-2010) and projected near- (2041-2060) and far- (2071-2090) future climates, using the 95th percentiles of conventional rainfall indices generated for climate scenarios downscaled by the LARS-WG weather generator from the 19 global climate models in the CMIP5 ensemble for the RCP8.5 emission scenario. Finally, we explored relationships between pollutant loss and the rainfall indices. Grassland field-scale monthly average nitrate losses increased from 0.39-1.07 kg ha^-1 (2016-2019) to 0.70-1.35 kg ha^-1 (2019-2020), whereas losses from grassland ploughed up for cereals, increased from 0.63-0.83 kg ha^-1 to 2.34-4.09 kg ha^-1. Nitrate losses at landscape scale increased during the 2019-2020 extreme wet-weather period to 2.04-4.54 kg ha^-1. Field-scale grassland monthly average sediment losses increased from 92-116 kg ha^-1 (2016-2019) to 281-333 kg ha^-1 (2019-2020), whereas corresponding losses from grassland converted to cereal production increased from 63-80 kg ha^-1 to 2124-2146 kg ha^-1. Landscape scale monthly sediment losses increased from 8-37 kg ha^-1 in 2018 to between 15 and 173 kg ha^-1 during the 2019-2020 wet-weather period. 2019-2020 was most representative of the forecast 95th percentiles of >1 mm rainfall for near- and far-future climates and this rainfall index was related to monitored sediment, but not nitrate, loss. The elevated suspended sediment loads generated by the extreme wet-weather of 2019-2020 therefore potentially provide some insight into the responses to the projected >1 mm rainfall extremes under future climates at the study location.

Keywords: Climate change; Nitrate; Suspended sediment; Water quality; Wet-weather.

Abstract

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