13 Jun 2023
 | 13 Jun 2023
Status: this preprint is currently under review for the journal HESS.

Afforestation impacts on terrestrial hydrology insignificant compared to climate change in Great Britain

Marcus Edmund Henry Buechel, Louise Slater, and Simon Dadson

Abstract. Widespread afforestation has been proposed internationally to reduce atmospheric carbon dioxide, however the specific hydrological consequences and benefits of such large-scale afforestation (e.g., Natural Flood Management) are poorly understood. We use a high-resolution land surface model, JULES, with realistic potential afforestation scenarios to quantify possible hydrological change across Great Britain in both present and projected climate. We assess whether proposed afforestation produces significantly different regional responses across regions; whether hydrological fluxes, stores and events are significantly altered by afforestation relative to climate; and how future hydrological processes may be altered up to 2050. Additionally, this enables determination of the relative sensitivity of land surface process representation in JULES compared to climate changes. For these three aims we run simulations using: (i) past climate with proposed land cover changes and known floods and drought events; (ii) past climate with independent changes in precipitation, temperature, and CO2; and (iii) a potential future climate (2020–2050). We find the proposed scale of afforestation is unlikely to significantly alter regional hydrology, however it can noticeably decrease low flows whilst not reducing high flows. The afforestation levels minimally impact hydrological processes compared to changes in precipitation, temperature, and CO2. Warming average temperatures (+ 3 °C) decreases streamflow, while rising precipitation (130 %) and CO2 (600 ppm) increase streamflow. Changes in high flow are generated because of evaporative parameterisations whereas low flows are controlled by runoff model parameterisations. In this study, land surface parameters within a land surface model do not substantially alter hydrological processes when compared to climate.

Marcus Edmund Henry Buechel et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-138', Steve Birkinshaw, 13 Jul 2023
  • RC2: 'Comment on hess-2023-138', Anonymous Referee #2, 18 Sep 2023

Marcus Edmund Henry Buechel et al.

Marcus Edmund Henry Buechel et al.


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Short summary
Afforestation has been proposed internationally, but the hydrological implications of such large increases in spatial extent of woodland are not fully understood. In this study we use a land surface model to simulate hydrology across Great Britain with realistic afforestation scenarios and potential climate changes. Countrywide afforestation minimally influences hydrology when compared to climate change, and reduces low streamflow whilst not lowering the highest flows.