Estimating groundwater recharge for Hanoi, Vietnam

• Published in: The Science of the total environment 2019-02, Vol.651 (Pt 1), p.1047-1057
• Main Authors: Hung Vu, V., Merkel, Broder J.
• Format: Article
• Language: English
• Subjects: Base-flow separation; Graphical separation method, empirical formulas; Hydrograph analysis; Recession curve displacement; Water table fluctuation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.09.225

Determining groundwater recharge is in particular in areas with Monsoon rainfall a challenge. Several methods were used to estimate groundwater recharge for the first time ever for the urban area of Hanoi city, Vietnam. Water table fluctuation method (WTF), hydrograph analyses including recession curve displacement, graphical separation, the Automated Web GIS-Base Hydrology Analysis Tool (WHAT), and empirical formulas were utilized. The mean recharge is approximately 340 mm/year accounting for 20% of precipitation in the period 1996 to 2009 with a certain decrease during this period. Baseflow separation methods show the highest values, whereas the displacement recession curve obtains the lowest recharge. The WTF methods approximate values are close to the mean value of all other proxies. The differences between all proxies are around 10%, and Spearman correlation is statistically significant. This indicates that these methods can be used to estimate recharge for this area. With long-term data, however, the results of WTF appear more consistent and more reasonable than the other approaches. [Display omitted] •Different methods for estimating the recharge in an area with tropical-monsoon climate (Hanoi, Vietnam) were tested•The water table fluctuation method (WTF) showed up to be the most reliable and reasonable technique•Empirical equations were derived for Hanoi from well-known empirical formulas based on rainfall as the only parameter.