Introducing Hydrological Modelling and Climate Change Scenarios

Before I delve into hydrological modelling of the SRB in the next post, I will first introduce the basics of hydrological modelling and climate change scenarios in this short blog post.

Hydrological Modelling

Hydrological models simulate and represent real-world hydrological processes: water flows and changes in water stores within the natural water cycle, such as surface runoff, infiltration, groundwater flow and discharge, through the use of mathematical equations (Ogden, 2021). They are widely employed for water resource management, and they are often used to predict future water trends under climate change.

Flows and stores within the water cycle that are represented in hydrological models (USGS, 2019).

Climate models and emission pathways

An essential part of all hydrological models are meteorological data, such as temperature, precipitation and solar radiation, which are used as input for the models (Garen, 2013). In order to predict future alterations in hydrological processes, climate change scenarios for meteorological data are applied to force hydrological models. 

General Circulation Models (GCMs) are mathematical models that simulate the global climate system (IPCC, 2007). The Coupled Model Intercomparison Project (CMIP) is a project that features most widely used GCMs, with the state-of-the-art GCMs being CMIP6 models (WCRP, 2022). Sometimes, GCMs are downscaled to Regional Climate Models (RCMs) to increase the spatial resolution of climate projections (Navarro-Racines et al., 2020).

A short video introducing climate models and CMIP (WCRP, 2022).

Alongside climate models, emission pathways have been developed to estimate future climate change scenarios. The most common examples of emission pathways are Representative Concentration Pathways (RCPs) (used with CMIP5 models) which describes future greenhouse gas emissions scenarios (Baek et al., 2013); and more recently Shared Socioeconomic Pathways (SSPs) (used with CMIP6 models) which include socio-economic development narratives in projecting future warming (Riahi et al., 2017).

Future simulations of temperature change compared to pre-industrial levels by RCPs (Baek et al., 2013).

Future simulations of emissions and radiative forcing by SSPs, compared with RCPs (Riahi et al., 2017).