Analysis of Runoff by SWAT Model to Assess Dam Safety Situation: a Case Study of Lam Khan Chu Reservoir, Chaiyaphum Province

a Case Study of Lam Khan Chu Reservoir, Chaiyaphum Province

Abstract

The runoff that flows into the reservoir during severe storms has the potential to affect the safety of large-sized reservoirs, especially considering the amount of groundwater around the dam ridge structure. The objective of this study was to assess the runoff in the Lam Kan Chu Reservoir located in the Chi River Basin during 2018-2020, covering the period of the tropical storm Noul. The SWAT model was applied to simulate the condition of runoff flowing into the reservoir compared to the recorded data from the reservoir, and the results of the analysis of the lateral flowing into the subsurface were compared with the measurements at the dam ridge. The results of the study found that calibration and validation accuracy of the model showed an index of R2 of 0.74 and NSE of 0.72, which was good. When the results were taken into the SWAT-Check model, the groundwater content was assessed and correlated with the groundwater level readings from the groundwater level dam behavior measurement instrument. The results indicated an R2 index of 0.51, which implied that the runoff in the reservoir affected the groundwater acting on the dam crest. The methods and results of this study are therefore expected to be a guideline for applying SWAT and SWAT-Check to analyze the level and groundwater in medium and small reservoirs that are not equipped with dam behavior measurement tools for the purpose of assessing the condition of dam safety.