Using regional climate models to understand hydrological risks from reforestation

Teo Hoong Chen and Prof Koh Lian Pin, Centre for Nature-based Climate Solutions

The NUS Centre for Nature-based Climate Solutions (CNCS) aims to produce policy-relevant science on nature-based climate solutions. Nature-based climate solutions (NCS) are a suite of land-based actions to better protect, manage and restore natural ecosystems to store carbon and mitigate climate change. 

Reforesting degraded lands is one of the most promising NCS, with over 850 million hectares of reforestation potential worldwide. Proponents of reforestation point to the importance of forests in intensifying the hydrological cycle, increasing precipitation recycling and water yield. However, studies also show that reforesting drier regions can increase evapotranspiration and reduce the water yield, negatively impacting the local ecosystem and communities.

As such, it is very important to understand where reforestation could increase and reduce water yield under future climatic conditions, especially for water-stressed regions, in order to guide policy-makers on where reforestation should and should not be carried out.

Using equations, energy and water balance models at the earth’s surface can estimate the amount of additional water resources consumed by forests (i.e. through evapotranspiration). Such calculations use spatial data and can generally be less computationally-intensive. However, understanding how much precipitation forests can return to the water catchment requires coupled land-atmosphere climate modelling, which is computationally-demanding.

There are also many other research questions that can only be robustly answered by taking into account land-atmosphere interactions, and thus require climate modelling. NUS HPC offers the capability to run regional climate models to answer these important research questions. Configuring, compiling and installing a climate model can be very complex and time-consuming, due to the many different components (land, sea, atmosphere, etc) involved in climate models. Many libraries and compilers have already been installed on the NUS HPC as environment modules, making it more convenient to compile new software.

Thanks to the computing resources and capabilities of NUS HPC, researchers at CNCS have better tools to understand hydrological risks from reforestation, and can design better solutions to meet the challenges of climate change.

Simulated precipitation in East Asia from regional climate models.