A pilot regional scale model of land use impacts on groundwater quality

Factors controlling the spatial distribution and temporal trend of groundwater quality at a national scale are important to investigate for sustaining livelihood and ecological balance. This study evaluated groundwater quality data for 12 parameters (n = 6405 for each parameter), collected from 97 groundwater monitoring stations (=289 monitoring wells) for ten years. Spatial distribution of groundwater quality parameters varied through the regional scale. Six parameters: T, EC, Ca2+, Mg2+, HCO3−, and Cl− were having dominant increasing trend, remaining pH, Eh, Na+, K+, SO42−, and NO3− showed a dominant decreasing trend over time. Among land use types, the upland fields had the highest mean of groundwater NO3− (22.2 mg/L), confirming plenty of application of fertilizers (5–10 kg/a more than standard) to upland fields. Means of groundwater Cl− and Na+ (705.3 and 298.4 mg/L, respectively) in the residential areas are greater than those in other land use types by 408–685.9, 154.3–274.2 mg/L, respectively. Agricultural activities were the main controlling factor of groundwater NO3− contamination in rural areas, domestic activities were responsible for groundwater Cl− and Na+ in urban areas, and seawater intrusion was controlling groundwater Cl− in coastal areas (within 10 km from sea). Groundwater hydrochemistry was controlled by the mechanism of geogenic rock and evaporation dominance. The rock dominance mechanism indicated that groundwater was interacting with rocks and resulted in groundwater chemistry. The findings of this study showed that groundwater was mainly contaminated by anthropogenic factors in some rural and residential areas. Effective measures by government authorities are needed to improve the groundwater quality.

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A PYTHON TOOL TO ESTIMATE LAND-USE IMPACTS ON GROUNDWATER NITRATE CONCENTRATIONS OBSERVED AT HIGH-CAPACITY PUMPING WELLS IN AN UNCONFINED GLACIAL AQUIFER

10.1130/abs/2020am-349317 ◽

2020 ◽

Author(s):

Stephanie Lynn DeVries ◽

◽

William Garrett Hooten ◽

William Garrett Hooten

Keyword(s):

Land Use ◽

High Capacity ◽

Land Use Impacts ◽

Pumping Wells ◽

Nitrate Concentrations

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Changing Land Use and Population Density Are Degrading Water Quality in the Lower Mekong Basin

Water ◽

10.3390/w13141948 ◽

2021 ◽

Vol 13 (14) ◽

pp. 1948

Author(s):

Flavia Tromboni ◽

Thomas E. Dilts ◽

Sarah E. Null ◽

Sapana Lohani ◽

Peng Bun Ngor ◽

...

Keyword(s):

Water Quality ◽

Land Use ◽

Population Density ◽

Local Population ◽

Reference Conditions ◽

Mekong River ◽

Land Use Impacts ◽

Wet Season ◽

Mekong Basin ◽

Lower Mekong Basin

Establishing reference conditions in rivers is important to understand environmental change and protect ecosystem integrity. Ranked third globally for fish biodiversity, the Mekong River has the world’s largest inland fishery providing livelihoods, food security, and protein to the local population. It is therefore of paramount importance to maintain the water quality and biotic integrity of this ecosystem. We analyzed land use impacts on water quality constituents (TSS, TN, TP, DO, NO3−, NH4+, PO43−) in the Lower Mekong Basin. We then used a best-model regression approach with anthropogenic land-use as independent variables and water quality parameters as the dependent variables, to define reference conditions in the absence of human activities (corresponding to the intercept value). From 2000–2017, the population and the percentage of crop, rice, and plantation land cover increased, while there was a decrease in upland forest and flooded forest. Agriculture, urbanization, and population density were associated with decreasing water quality health in the Lower Mekong Basin. In several sites, Thailand and Laos had higher TN, NO3−, and NH4+ concentrations compared to reference conditions, while Cambodia had higher TP values than reference conditions, showing water quality degradation. TSS was higher than reference conditions in the dry season in Cambodia, but was lower than reference values in the wet season in Thailand and Laos. This study shows how deforestation from agriculture conversion and increasing urbanization pressure causes water quality decline in the Lower Mekong Basin, and provides a first characterization of reference water quality conditions for the Lower Mekong River and its tributaries.

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