Groundwater dynamics in the Vietnamese Mekong Delta: Trends, memory effects, and response times

Duy, Nguyen Le; Nguyen, Triet Van Khanh; Nguyen, Dung Viet; Tran, Anh; Nguyen, Ha Thi Thu; Heidbüchel, Ingo; Merz, Bruno; Apel, Heiko

doi:10.1016/j.ejrh.2020.100746

Cited by 25 publications

(19 citation statements)

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“…In addition, 9/116 wells (7.8%) show no statistically significant time trend of groundwater level, mostly in the shallow aquifers. These results are consistent with previous studies (Wagner et al 2012;Duy et al 2021) and the fact that most of the major groundwater extraction wells in the VMD are located in deep aquifers where groundwater storage is more stable and less prone to pollution than groundwater in shallow aquifers. Consequently, given the slow groundwater recharge from the upper aquifers, groundwater levels tend to decline more rapidly in deep aquifers in the VMD.…”

Section: Trends Of Groundwater Levelsupporting

confidence: 93%

“…This decline has also depleted water bodies (i.e., groundwater capture) and threatened groundwater sustainability (Gleeson et al 2020;Elshall et al 2021). Although the trends of groundwater levels have been recently investigated (Wagner et al 2012;Duy et al 2021), the connections between the groundwater system and climate variability in the VMD remain poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Responses of groundwater to precipitation variability and ENSO in the Vietnamese Mekong Delta

Pham

Bui

et al. 2021

Hydrology Research

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Groundwater is a critical component of water resources and has become the primary water supply for agricultural and domestic uses in the Vietnamese Mekong Delta (VMD). Widespread groundwater level declines have occurred in the VMD over recent decades, reflecting that extraction rates exceed aquifer recharge in the region. However, the impacts of climate variability on groundwater system dynamics in the VMD remain poorly understood. Here, we explore recent changes in groundwater levels in shallow and deep aquifers from observed wells in the VMD and investigate their relations to the annual precipitation variability and El Niño–Southern Oscillation (ENSO). We show that groundwater level responds to changes in annual precipitation at time scales of approximately 1 year. Moreover, shallow (deep) groundwater in the VMD appears to correlate with the ENSO over intra-annual (inter-annual) time scales. Our findings reveal a critical linkage between groundwater level changes and climate variability, suggesting the need to develop an understanding of the impacts of climate variability across time scales on water resources in the VMD.

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Section: Trends Of Groundwater Levelsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Responses of groundwater to precipitation variability and ENSO in the Vietnamese Mekong Delta

Pham

Bui

et al. 2021

Hydrology Research

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“…The VMD is characterized by the relatively flat terrain <5 m. It observes tropical climate with distinct wet (May to November) and dry season (December to April). About 30-40 % of the delta is inundated during rainy (wet) season influenced by the Indian Summer Monsoon (Duy et al, 2021). The average annual precipitation across the basin ranges between 1,300 mm to 2,500 mm of which 80-90% is attributed by the precipitation during the wet season accounting for a discharge load of 75-85 % (Le et al, 2021).…”

Section: Vietnam Mekong Deltamentioning

confidence: 99%

Evaluation of gridded precipitation products in the selected sub-basins of Lower Mekong River Basin

Dhungana

Shrestha

Vân

et al. 2022

Preprint

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Hydrological and meteorological studies demand accurate, continuous long-term reliable and uniformly distributed precipitation datasets. A plethora of gridded precipitation products (GPPs) has made their place as an alternate to rain gauge records. However, GPPs house inherent depending on the type of data, data density, gridding algorithm, etc. Hence it is crucial to evaluate them prior to their application. This study evaluated eight GPPs: Asian Precipitation Highly Resolved Observational Data Integration towards Evaluation data (APHRODITE), Climate Prediction Center (CPC), Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), Southeast Asian Observed dataset (SA-OBS), Climate Prediction Center Morphing Technique (CMORPH), The Tropical Rainfall Measuring Mission (TRMM) -daily products and Climate Research Unit (CRU) and Global Precipitation Climatology Center (GPCC)- monthly products for 17 years (1998-2014). An entropy-based weight calculation for each statistical indices and compromise programming was employed to rank GPPs in the selected sub-basins basins (Nam Ngum River Basin (NRB) and Vietnam Mekong Delta (VMD)) of Lower Mekong Region (LMR) for mean and six extreme precipitation indices. The correlation coefficient (r), Root Mean Square Error (RMSE), and skilled score (SS) were the statistical indices used in this study. In terms of capturing mean monthly precipitation, GPCC outweighed all other products for both the studied basin. However, APHRODITE ranked first on a daily based product based on compromise programming for NRB. APHRODITE consistently recorded r between 0.85 to 0.95, RMSE in between 50 and 100 mm/month and SS between 0.72 to 0.90 for the 5 observed stations. Similarly, in case of VMD, TRMM ranked first for the daily precipitation products with r in between 0.8 to 0.95, RMSE between 50 to 70 mm/month and SS between 0.56 to 0.9 when evaluated with 11 observed stations. The APHRODITE for NRB and TRMM for VMD could be reliable GPPs for hydrological and meteorological studies.

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“…Groundwater is influenced by natural and non-natural factors [6], such as land use/cover, rainfall, recharge, geology, soil type, evaporation, and abstraction [7]. With the increased demand for water fuelled by an increase in the population, an increase in abstraction rates has been witnessed, causing a decline in groundwater levels [8,9]. An increase in urbanization increases the area under built and pavement areas, which reduces recharge and consequently causes a decline in groundwater levels [6].…”

Section: Introductionmentioning

confidence: 99%

“…According to a study by Lam et al in Vietnam, a decrease in rainfall decreased recharge and groundwater levels [9]. A study in the Vietnamese Mekong Delta by Duy et al found that an increase in abstraction rates led to a decline in groundwater levels [8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Recharge and Abstraction on Groundwater Levels

2022

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Groundwater constitutes 99% of all liquid freshwater globally that is available for human use. Groundwater levels in the Nairobi aquifer system (NAS) have been declining over time because of excessive abstraction fueled by increased water demand. This has increased the cost of pumping and drilling boreholes, which is unsustainable. The objective of this study is to determine the effect of recharge and abstraction on groundwater levels using a more realistic approach by estimating recharge using the SWAT model while considering climatic data, soil type, land use/cover, and topography. Recharge obtained from SWAT was applied in MODFLOW to model the groundwater system. Results showed that the average annual recharge was 73 mm, which is about 9.7% of the precipitation. Groundwater levels decreased with an increase in abstraction and a decrease in recharge and vice versa. Groundwater levels will decrease by 76 m by the year 2063 if the abstraction rate is kept constant and the recharge is maintained, and will decrease by 14m by the year 2030 if the trend of abstraction rate continues to increase while recharge is kept constant. The abstraction rate should be regulated according to available recharge and recharge enhanced to avoid possible depletion of groundwater. Doi: 10.28991/CEJ-2022-08-05-05 Full Text: PDF

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Groundwater dynamics in the Vietnamese Mekong Delta: Trends, memory effects, and response times

Cited by 25 publications

References 50 publications

Responses of groundwater to precipitation variability and ENSO in the Vietnamese Mekong Delta

Responses of groundwater to precipitation variability and ENSO in the Vietnamese Mekong Delta

Evaluation of gridded precipitation products in the selected sub-basins of Lower Mekong River Basin

Effect of Recharge and Abstraction on Groundwater Levels

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