Numerical Study on the Influence of Weir Construction on Near-Surface Atmospheric Conditions

Abstract

Changes in land use/land cover (LULC) have an impact on weather and climate. Gumi Weir in the Nakdong River Basin of South Korea was built and led to changes of LULC in the river in which the width of the river was extended by 300 m on average from land to water. In this study, in order to analyze the effect of the LULC change on weather variables, the Large Eddy Simulation of Weather Research and Forecasting model was used based on the LULC before and after weir construction. The expanded river width increased the latent heat flux (LHF) and mixing ratio (q). The changes in the sensible heat flux (SHF) subsequently influenced the changes in the air temperature (Ta) around the river, where the LULC was directly changed. The distance of affected area due to the LULC change was investigated using a paired t-test. The results of the paired t-test revealed that an increase in the Nakdong river width led to a noticeable change in Ta and q with the mean distance of affected area up to 1100 m from the river shores. The results of this study could offer an understanding of the effects of small weir construction on local weather changes.