Hydrological Response of Tropical Catchments to Climate Change as Modeled by the GR2M Model: A Case Study in Costa Rica

Abstract

This study aimed to assess the impacts of climate change on streamflow characteristics of five tropical catchments located in Costa Rica. An ensemble of five General Circulation Models (GCMs), namely HadGEM2-ES, CanESM2, EC-EARTH, MIROC5, MPI-ESM-LR dynamically downscaled by two Regional Climate Models (RCMs), specifically HadRM3P and RCA4, was selected to provide an overview of the impacts of different climate change scenarios under Representative Concentration Pathways (RCPs) 2.6, 4.5 and 8.5 using the 1961–1990 baseline period. The GR2M hydrological model was used to reproduce the historical monthly surface runoff patterns of each catchment. Following calibration and validation of the GRM2 model, the projected impact of climate change on streamflow was simulated for a near-future (2011–2040), mid-future (2041–2070) and far-future (2071–2100) for each catchment using the bias-corrected GCM-RCM multimodel ensemble-mean (MEM). Results anticipate wetter conditions for all catchments in the near-future and mid-future periods under RCPs 2.6 and 4.5, whereas dryer conditions are expected for the far-future period under RCP 8.5. Projected temperature trends indicate consistently warmer conditions with increasing radiative forcing and future periods. Streamflow changes across all catchments however are dominated by variations in projected precipitation. Wetter conditions for the near-future and mid-future horizons under RCPs 2.6 and 4.5 would result in higher runoff volumes, particularly during the late wet season (LWS). Conversely, dryer conditions for the far-future period under RCP8.5 would result in considerably lower runoff volumes during the early wet season (EWS) and the Mid-Summer Drought (MSD). In consequence, projected seasonal changes on streamflow across all catchments may result in more frequent flooding, droughts, and water supply shortage compared to historical hydrological regimes.

Flood projections for selected Costa Rican main basins using CMIP6 climate models downscaled output in the HBV hydrological model for scenario SSP5-8.5

“…These previous studies do not characterize daily variability from the models. In particular, the most recent study by Mendez et al (2022) which analyzed climate change hydrological projections for 5 selected Costa Rican subbasins is different to our study, not only in the details of datasets used, but also in a very fundamental way as the authors used monthly instead of daily data and the delta downscaling method they applied consisted in shifting the observational dataset variability with a perturbation of the future monthly GCM-RCM anomalies with respect to the baseline period. This is different to the application of the daily downscaling method that we are presenting, which is based in conserving the daily variability of the bias-corrected GCMs.…”

“…It is important to note that floods studies in tropical regions are generally scarce (some exceptions in Asia can be found in Das et al, 2022;Pandey et al, 2022;Mahato et al, 2022), and in Central America the availability of regional/country studies is even rarer (for Costa Rica see Mendez et al, 2022). In higher and mid latitudes, the main control on hydrology can be related to other physical processes, for example snow, which produces a very different streamflow seasonal cycle (and flood characteristics) compared to places without snow, as in the former case the precipitation is stored as snow during the winter and released in a smoother peak during the spring.…”

“…Karmalkar et al, 2008;Stan et al, 2020;Castillo and Amador, 2020), while fewer studies have used the climate model precipitation and temperature projections as input in hydrological models (e.g. Hidalgo et al, 2013;Imbach et al, 2012;Moreno et al, 2019;Mendez et al, 2022). These previous studies do not characterize daily variability from the models.…”

Comparison of Hydrological Platforms in Assessing Rainfall-Runoff Behavior in a Mediterranean Watershed of Northern Morocco

“…For that, it must be managed and quantified by the implementation of tools that could help decision-support and management processes. Among these tools, hydrological models have emerged over the last thirty years [1][2][3][4][5][6][7], particularly models of rainfall-runoff transformation, recharge, and evaporation [8][9][10]. The primary focus of hydrological modeling is to reproduce the flows with the smallest possible error.…”