Dynamic response of land use and river nutrient concentration to long-term climatic changes

Gianbattista Bussi,Victoria Janes,Paul G Whitehead,Simon J Dadson,Ian P Holman

doi:10.1016/j.scitotenv.2017.03.069

Gianbattista Bussi, Victoria Janes + Show 3 more

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https://doi.org/10.1016/j.scitotenv.2017.03.069

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Abstract

The combined indirect and direct impacts of land use change and climate change on river water quality were assessed. A land use allocation model was used to evaluate the response of the catchment land use to long-term climatic changes. Its results were used to drive a water quality model and assess the impact of climatic alterations on freshwater nitrate and phosphorus concentrations. Climatic projections were employed to estimate the likelihood of such response. The River Thames catchment (UK) was used as a case-study. If land use is considered as static parameter, according to the model results, climate change alone should reduce the average nitrate concentration, although just by a small amount, by the 2050s in the Lower Thames, due to reduced runoff (and lower export of nitrate from agricultural soils) and increased instream denitrification, and should increase the average phosphorus concentration by 12% by the 2050s in the Lower Thames, due to a reduction of the effluent dilution capacity of the river flow. However, the results of this study also show that these long-term climatic alterations are likely to lead to a reduction in the arable land in the Thames, replaced by improved grassland, due to a decrease in agriculture profitability in the UK. Taking into account the dynamic co-evolution of land use with climate, the average nitrate concentration is expected to be decreased by around 6% by the 2050s in both the upper and the lower Thames, following the model results, and the average phosphorus concentration increased by 13% in the upper Thames and 5% in the lower Thames. On the long term (2080s), nitrate is expected to decrease by 9% and 8% (upper and lower Thames respectively) and phosphorus not to change in the upper thames and increase by 5% in the lower Thames.

Highlights

Land use is widely acknowledged as a key driver of change in catchment processes and properties, it is challenging to predict how it will change in the future subject to stressors such as climate change, technology change and human population increases
Contrary to most of the previous studies in the field of climate and land use/land cover changes impact assessment, in the present study the land use was not treated as a static parameter of the catchment, but rather as a dynamic variable, which varies depending on the long term response of European agriculture and forestry to climate change
Using a land use allocation model coupled with a water quality model, this study demonstrated a methodological approach to evaluate the joint impact of climate and land use changes on water quality, taking into account the autonomous adaptation of land use and agriculture to a changing climate

Summary

Introduction

Land use is widely acknowledged as a key driver of change in catchment processes and properties, it is challenging to predict how it will change in the future subject to stressors such as climate change, technology change and human population increases. Natural vegetation responds dynamically to climatic variations (RuizPérez et al, 2016). These adaptations can have hydrological and ecological effects (Dale, 1997). One example of widespread human-induced land use change is agriculture. Agriculture is the economic sector that is likely to suffer the greatest financial impact as a result of climate change (Lobell et al, 2011). Farmers are expected to adapt to climate change by switching activities to those that are most profitable, given the new conditions they will face (Fezzi et al, 2015)

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