Evaluation of Future Climate and Potential Impact on Streamflow in the Upper Nan River Basin of Northern Thailand

Miyuru B Gunathilake,Anura S Gunathilake,Imiya M Chathuranika,Anushka Perera,Upaka Rathnayake,Yasasna V Amaratunga,Roberto Coscarelli

doi:10.1155/2020/8881118

Abstract

Water resources in Northern Thailand have been less explored with regard to the impact on hydrology that the future climate would have. For this study, three regional climate models (RCMs) from the Coordinated Regional Downscaling Experiment (CORDEX) of Coupled Model Intercomparison Project 5 (CMIP5) were used to project future climate of the upper Nan River basin. Future climate data of ACCESS_CCAM, MPI_ESM_CCAM, and CNRM_CCAM under Representation Concentration Pathways RCP4.5 and RCP8.5 were bias-corrected by the linear scaling method and subsequently drove the Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) to simulate future streamflow. This study compared baseline (1988–2005) climate and streamflow values with future time scales during 2020–2039 (2030s), 2040–2069 (2050s), and 2070–2099 (2080s). The upper Nan River basin will become warmer in future with highest increases in the maximum temperature of 3.8°C/year for MPI_ESM and minimum temperature of 3.6°C/year for ACCESS_CCAM under RCP8.5 during 2080s. The magnitude of changes and directions in mean monthly precipitation varies, with the highest increase of 109 mm for ACESSS_CCAM under RCP 4.5 in September and highest decrease of 77 mm in July for CNRM, during 2080s. Average of RCM combinations shows that decreases will be in ranges of −5.5 to −48.9% for annual flows, −31 to −47% for rainy season flows, and −47 to −67% for winter season flows. Increases in summer seasonal flows will be between 14 and 58%. Projection of future temperature levels indicates that higher increases will be during the latter part of the 20th century, and in general, the increases in the minimum temperature will be higher than those in the maximum temperature. The results of this study will be useful for river basin planners and government agencies to develop sustainable water management strategies and adaptation options to offset negative impacts of future changes in climate. In addition, the results will also be valuable for agriculturists and hydropower planners.

Highlights

Multiple global climate model (GCM) or regional climate models (RCMs) combined with several emission scenarios, downscaling methods, and bias correction methods are recommended for climate change modeling studies
A land use map of 500 m resolution and a scale of 1 : 50,000 and soil cover map with 1 km resolution and a scale of 1 : 100,000 for the year 2010 were obtained from the Land Development Department (LDD) of ailand. ree RCMs, ACCESS_CCAM, MPI_ESM_CCAM, and CNRM_CCAM from Coordinated Regional Downscaling Experiment (CORDEX) platform developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) under RCP4.5 and RCP8.5, were used to project
Hydrological Model Development. e monthly hydrographs obtained during calibration and validation at streamflow gauging station N.13A are illustrated through Figures 3(a) and 3(b). e flow hydrographs are given in the format of discharge per drainage area for easy comparison to the corresponding rainfall. e visual comparisons and statistical indicators strongly inferred that the developed Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) model is capable of tracking monthly streamflow of the upper Nan River basin reasonably well with few discrepancies

Summary

Materials and Methods

A land use map of 500 m resolution and a scale of 1 : 50,000 and soil cover map with 1 km resolution and a scale of 1 : 100,000 for the year 2010 were obtained from the Land Development Department (LDD) of ailand. Spatial datasets Topography Soil cover Land use RCMs under RCP4.5 and RCP8.5 RCM ACCESS_CCAM MPI_ESM_CCAM CNRM_CCAM. E HEC-HMS model has been used in studies related to climate change impact assessment on streamflow [85, 86], reservoir spillway capacity studies [87], urbanization impact on hydrology [88], and operationalizing a flood forecasting decision support system [89]. CORDEX climatic data had been previously used for climate change studies by Sharannya et al [43], Endris et al [91], Solman [92], Virgilio et al [93], and Prein et al [94] in Asia, South America, Europe, North America, Africa, and Australia

Methodology

Results and Discussion

Variable Maximum temperature Minimum temperature Precipitation