Identifying Groundwater and River Water Interconnections Using Hydrochemistry, Stable Isotopes, and Statistical Methods in Hanumante River, Kathmandu Valley, Central Nepal

Bajracharya, Ramita; Nakamura, Takashi; Ghimire, Suresh Kumar; Shakya, Bijay Man; Tamrakar, Naresh Kazi

doi:10.3390/w12061524

Cited by 10 publications

(6 citation statements)

References 59 publications

(104 reference statements)

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“…A number of meat shops, hospitals, and a pharmacy were present in the surroundings (within 200 m) of the shallow wells where 8 ARGs were detected. Contamination of shallow dug wells by wastewater from such establishments and discharging of untreated wastewater and partially treated municipal, industrial, and hospital wastewaters to rivers may have affected shallow groundwater ( Mackie et al, 2006 ; Elliott et al, 2018 ; Bajracharya et al, 2020 ; Hubbard et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

“…( Ghaju Shrestha et al, 2017 ), as well as human and animal fecal contamination in these water sources ( Malla et al, 2015 , 2018a , b , 2019 ). Similarly, river water, which is extensively used for irrigation of vegetable farms in the valley, is highly contaminated with pathogens ( Shrestha et al, 2017b ), and the interconnection between river water and groundwater of the Kathmandu Valley ( Bajracharya et al, 2020 ) indicates a high possibility of pathogen contamination of groundwater.…”

Section: Methodsmentioning

confidence: 99%

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Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

et al. 2022

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Antibiotic-resistant bacteria-associated infections are responsible for more than 1.2 million annual deaths worldwide. In low- and middle-income countries (LMICs), the consumption of antibiotics for human and veterinary uses is not regulated effectively. Overused and misused antibiotics can end up in aquatic environments, which may act as a conduit for antibiotic resistance dissemination. However, data on the prevalence of antibiotic resistance determinants in aquatic environments are still limited for LMICs. In this study, we evaluated the prevalence and concentration of antibiotic resistance genes (ARGs) in different drinking and environmental water sources collected from the Kathmandu Valley, Nepal, using droplet digital polymerase chain reaction to understand the current situation of ARG contamination. River water and shallow dug well water sources were the most contaminated with ARGs. Almost all samples contained sul1 (94%), and intI1 and tet(A) were detected in 83 and 60% of the samples, respectively. Maximum ARG concentration varied between 4.2 log10 copies/100 ml for mecA and 9.3 log10 copies/100 ml for sul1. Significant positive correlations were found between ARGs (r > 0.5, p < 0.01), except for mecA, qnrS, and vanA. As sul1 and intI1 were detected in almost all samples, the presence of these genes in a given sample may need to be considered as background antibiotic resistance in LMICs. Therefore, monitoring of ARGs, such as β-lactam ARGs, quinolone resistance genes, and vancomycin resistance genes, may provide a better picture of the antibiotic resistance determinants in aquatic environments of LMICs.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

et al. 2022

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“…Mann Whitney test revealed significant variation (p<0.05) between the Bheri and the Babai River systems with regard to Ca 2+ , Mg 2+ , HCO 3 − and SO 4 2− (Figure 2). Ca 2+ and HCO 3 − are often the most dominant cation and anion in freshwater systems globally (Wetzel, 2001) and a large number of studies across Nepal and elsewhere have reported the dominance of these ions in different freshwater bodies (Lacoul and Freedman, 2005;Bajracharya et al, 2020;Bhatta et al, 2022). In contrast, the concentrations of K + ions were lowest in both the water bodies.…”

Section: Major Ions and Their Seasonal Variationmentioning

confidence: 99%

Major Ion Chemistry of the Bheri (Snow-Fed) and the Babai (Rain-Fed) River Systems in Western Nepal: Implication on Water Quality

Khatri¹,

Gurung²,

Jha³

et al. 2023

Environ. Nat. Resour. J.

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Inter Basin Water Transfer (IBWT) is a water resource stressor globally with negative environmental impacts. This study describes the major ions and hydrochemistry of the first ever ongoing IBWT from snow-fed Bheri River to rain-fed Babai River in Western Nepal. Water samples from 10 sites, five from each river system, were collected in HDPE bottles for major ions (Ca^(2+), Mg^(2+), Na^+, K^+, HCO_3^-, Cl^-, SO_4^(2-), NO_3^-, CO_3^(2-)) along with the estimation of pH, temperature and conductivity encompassing winter, spring, summer, and autumn in 2018. Ca^(2+)and HCO_3^- were the most dominant cation and anion, respectively, with 〖Ca-Mg-HCO〗_3 water type in both the river systems. Mann Whitney test revealed significant variation (p<0.05) between the two river systems with regard to Ca^(2+), Mg^(2+), HCO_3^- , and SO_4^(2-). Kruskall Wallis test revealed significant variations between seasons in pH, temperature, Na^+, K^+, and Cl^- in Bheri River system, and in pH, TDS, temperature, Na^+, K^+ , Cl^- and SO_4^(2-) in Babai River system. Carbonate weathering was the main mechanism of ionic sources with insignificant contribution from silicate weathering. Relatively higher concentrations of the major ions during the dry seasons probably indicate the dilution effect of monsoon. Higher concentrations of the ions in the Babai River system reflect the latter’s bedrock geology with susceptibility to erosion. With Nepal’s future plans of IBWTs and their environmental implications, this finding could be helpful in mitigating the negative consequences of IBWTs in the impact assessment and management of IBWT projects because of their implications on management of aquatic resources.

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“…There is a significant difference in water quality entering the Valley floor from headwater catchments with natural land uses (Davids et al 2018). The shallow groundwater quality does not improve as quickly because the amount of groundwater in storage is high, and groundwater flow velocities are low, which leads to a slower rate of change (Bajracharya et al 2020). It is also possible that shallow aquifer recharge in the Valley floor is of lower quality because of extensive overlying-built land-uses.…”

Section: Impact Of Stream-aquifer Interaction In Groundwater Qualitymentioning

confidence: 99%

Streams, sewage, and shallow groundwater: stream-aquifer interactions in the Kathmandu Valley, Nepal

Prajapati

Overkamp

Moesker

et al. 2021

Sustain. Water Resour. Manag.

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The Kathmandu Valley in Nepal is facing a water quantity and quality crisis due to rapid urbanization and haphazard water and wastewater planning and management. Annually, groundwater extractions in the Kathmandu Valley exceed capture, resulting in groundwater table declines. Streams are often important sources of recharge to (or destination of discharges from) aquifers. However, stream-aquifer interactions in the Kathmandu Valley are poorly understood. To improve this understanding, we performed topographic surveys of water levels, and measured water quality, in streams and adjacent hand-dug wells (shallow aquifer). In pre-monsoon, 12% (2018) and 44% (2019) of wells had water levels higher than adjacent streams, indicating mostly a loss of stream water to the aquifer. However, in post-monsoon, 69% (2018) and 70% (2019) of wells had water levels higher than adjacent streams, indicating that monsoon rainfall contributes to shallow aquifer recharge which, at least temporarily, causes streams to transition from losing to gaining. Concentrations of all water quality parameters (electrical conductivity, ammonia, alkalinity, and hardness) were higher in the pre-monsoon compared to post-monsoon in both streams and wells. There was no recurring trend in water level difference longitudinally from upstream to downstream. However, water quality in streams and wells depleted from upstream to downstream. While we clearly observed seasonal refilling of the shallow aquifer, the role of the deep aquifer in seasonal storage processes deserve future research attention.

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Identifying Groundwater and River Water Interconnections Using Hydrochemistry, Stable Isotopes, and Statistical Methods in Hanumante River, Kathmandu Valley, Central Nepal

Cited by 10 publications

References 59 publications

Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

Prevalence of antibiotic resistance genes in drinking and environmental water sources of the Kathmandu Valley, Nepal

Major Ion Chemistry of the Bheri (Snow-Fed) and the Babai (Rain-Fed) River Systems in Western Nepal: Implication on Water Quality

Streams, sewage, and shallow groundwater: stream-aquifer interactions in the Kathmandu Valley, Nepal

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