Estimation of Watershed Hydrochemical Responses to Future Climate Changes Based on CMIP6 Scenarios in the Tianhe River (China)

Abstract

The impacts of future climate changes on watershed hydrochemical processes were assessed based on the newest Shared Socioeconomic Pathways (SSP) scenarios in Coupled Model Intercomparison Project Phase 6 (CMIP6) in the Tianhe River in the middle area of China. The monthly spatial downscaled outputs of General Circulation Models (GCMs) were used, and a new Python procedure was developed to batch pick up site-scale climate change information. A combined modeling approach was proposed to estimate the responses of the streamflow and Total Dissolved Nitrogen (TDN) fluxes to four climate change scenarios during four future periods. The Long Ashton Research Station Weather Generator (LARS-WG) was used to generate synthetic daily weather series, which were further used in the Regional Nutrient Management (ReNuMa) model for scenario analyses of watershed hydrochemical process responses. The results showed that there would be 2–3% decreases in annual streamflow by the end of this century for most scenarios except SSP 1–26. More streamflow is expected in the summer months, responding to most climate change scenarios. The annual TDN fluxes would continue to increase in the future under the uncontrolled climate scenarios, with more non-point source contributions during the high-flow periods in the summer. The intensities of the TDN flux increasing under the emission-controlled climate scenarios would be relatively moderate, with a turning point around the 2070s, indicating that positive climate policies could be effective for mitigating the impacts of future climate changes on watershed hydrochemical processes.

The impacts of climate changes on watershed streamflow and total dissolved nitrogen in Danjiang Watershed, China

“…This means that the streamflow in the study area is more sensitive to future climate change in autumn and winter. The increasing trends of the annual TDN flux in this study area were lower than those in other similar areas (Sha et al 2021a). This was mainly due to the decrease of non-point source pollution loading resulting from the decrease in streamflow.…”

“…The decreasing trends of the annual streamflow in the study area were generally similar to those in other cases. However, under the best emission-controlled scenario of SSP1-26, other cases showed an increase in annual streamflow (Sunde et al 2018;Sha et al 2021a), but the current study area still showed a decreasing trend. This indicates that the study area is more sensitive to climate change.…”

“…Assessing the variability of watershed hydrochemical processes under possible climate change conditions is crucial for effectively managing water resources and the environment (Shrestha & Wang 2019;Ross & Randhir 2022). Previous studies have shown that the global climate will change significantly in the future under the influence of human activities (Sha et al 2021a;Orke & Li 2022). The changes reflecting on the watershed scale will result in changes in local precipitation and temperature, which in turn would modify the watershed hydrochemical process and lead to changes in streamflow and non-point source pollution features (Arab Amiri & Gocić2021).…”

Projection of the land use and climate change impacts on runoff in the Bojnourd catchment under CMIP6 Scenarios

“…In climate change conditions, the Long-Ashton Research Station -Weather Generator (LARS-WG) meteorological data generation model is used for exponential downscaling and synthetic weather data generation. In other words, this model has been extensively used to estimate the basin's response to climate change (Sha et al, 2021). This model uses a semi-empirical series to calculate the length of dry and wet periods and generate synthetic data on temperature, precipitation, and solar radiation.…”