ALBERT

Description:    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. Content Type Journal Article Category Report Pages 1-16 DOI 10.1007/s10040-012-0889-4 Authors Duong Du Bui, Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1–1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397 Japan Akira Kawamura, Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1–1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397 Japan Thanh Ngoc Tong, Center of Water Resources Planning and Investigation, Ministry of Natural Resources and Environment, 10-42, Trancung Street, Hanoi, Vietnam Hideo Amaguchi, Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1–1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397 Japan Naoko Nakagawa, Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1–1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397 Japan Journal Hydrogeology Journal Online ISSN 1435-0157 Print ISSN 1431-2174