Developing a Digital Twin to support the resilience of young trees to drought

The EU CARMINE project (https://carmine-project.eu/) aims to support urban and surrounding metropolitan communities to become more climate resilient. The project focuses on heat, wildfires, flooding, pollution and drought across eight case study areas in Europe. Birmingham, located within the West Midlands Combined Authority (WMCA), serves as the UK case study area. High priority climate hazards for Birmingham are extreme heat, as well as pluvial flooding caused by extreme precipitation events. Increasing urban tree cover to alleviate these hazards could be a promising nature-based solution. However, a large amount of newly planted trees tends to wilt or die due to drought stress.

To assist the Council and community volunteers in maintaining the young trees during drought events, we are developing a digital twin framework to identify when and where young trees across Birmingham need watering. Common indicators include daily plant available water and the level of drought/wetness for the last few weeks. These indicators are based on soil moisture content, usually at different depths. Unfortunately, such measurements are sparse or absent in urban areas. We use the Joint UK Land-Environment Simulator (JULES) model forced by the UK weather forecasting model UKV at a spatial resolution of 1.5km, to estimate soil moisture content. Using machine learning techniques, we emulate JULES outputs to provide soil moisture estimations in a faster, more efficient and more flexible way. Platforms developed through the CARMINE project allow us to communicate the need for watering to interested communities. This approach is an important step to support communities and city authorities to improve the management of urban trees and resilience of cities to climate hazards like heat waves and flooding.

This approach explores how a digital twin, combined with an emulation of JULES soil moisture using ML techniques, could provide drought information for young trees more efficiently. It has the potential to scale beyond the case study area of Birmingham and transfer the digital twin to other urban areas.