Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam

Bui, Duong Du; Kawamura, Akira; Tong, Thanh Ngoc; Amaguchi, Hideo; Nakagawa, Naoko

Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam | Analyse spatio-temporelle des tendances piézométriques actuelles dans le delta de la rivière Rouge, Vietnam Análisis espacio temporal de tendencias recientes en niveles de agua subterránea en el Delta del Red River, Vietnam 越南红河三角洲近期地下水水位时空趋势分析ベトナム紅川デルタにおける近年の地下水位トレンドの時空間解析 Análise espácio-temporal da tendência recente de variação do nível da água subterrânea no Delta do Rio Vermelho, Vietname Xu hướng biến đổi mực nước dưới đất theo không gian và thời gian ở đồng bằng châu thổ Sông Hồng, Việt nam

2012

Bui, Duong Du | Kawamura, Akira | Tong, Thanh Ngoc | Amaguchi, Hideo | Nakagawa, Naoko

A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995–2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen’s slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35 % of the wells in the unconfined aquifer showed downward trends, while about 21 % showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3 m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.

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