Investigating Groundwater Variability and Hydrological Parameters using Trend and Correlation Analysis for the Lower Mekong River Basin Countries

Abstract

Groundwater is an important source of freshwater in the Lower Mekong River Basin (LMRB). Understanding the relationship between groundwater variability and hydrological parameters is critical for the sustainable water resource management. The study applied the Earth Observation (EO) data and the Google Earth Engine (GEE) platform for investigating trend and correlation values between groundwater variability and hydrological parameters in the LMRB from 2002 to 2017. The results of this study show that there are increasing trends of precipitation, evapotranspiration (ET), and runoff in Laos, Thailand, and Vietnam but it is clearly found decreasing trends in Cambodia. From the relationship between liquid water equivalent thickness (LWE) and water storage changes (ΔS), a travel time of groundwater recharge in the study area is about 1 month due to p-value > 0.05 for lags of 2-3 months. Precipitation has a relationship with the LWE stronger than ET and runoff. Moreover, the study indicates the LWE of four countries in the LMRB region has a decreasing trend during 2002-2006 and an increasing trend during 2007-2011 and continuously decreasing trend during 2011-2016. Thus, the study can provide an information for the groundwater resource management in the study area such as determining groundwater recharge areas etc.