Middle Ganga Plain Research Articles

Evaluation of hydrogeochemical processes in the Pleistocene aquifers of Middle Ganga Plain, Uttar Pradesh, India

Evaluation of major ion chemistry and solute acquisition process controlling water chemical composition were studied by collecting a total of fifty-one groundwater samples in shallow ( 25 m) in the Varanasi area. Hydrochemical facies, Mg-HCO3 dominated in the largest part of shallow groundwater followed by Na-HCO3 and Ca-HCO3 whereas Ca-HCO3 is dominated in deep groundwater followed by Mg-HCO3 and Na-HCO3. High As concentration (>50 μg/l) is found in some of the villages situated in northeastern parts (i.e. adjacent to the concave part of the meandering Ganga river) of the Varanasi area. Arsenic contamination is confined mostly in tube wells (hand pump) within the Holocene newer alluvium deposits, whereas older alluvial aquifers are having arsenic free groundwater. Geochemical modeling using WATEQ4F enabled prediction of saturation state of minerals and indicated dissolution and precipitation reactions occurring in groundwater. Majority of shallow and deep groundwater samples of the study area are oversaturated with carbonate bearing minerals and under-saturated with respect to sulfur and amorphous silica bearing minerals. Sluggish hydraulic conductivity in shallow aquifer results in higher mineralization of groundwater than in deep aquifer. But the major processes in deep aquifer are leakage of shallow aquifer followed by dominant ion-exchange and weathering of silicate minerals.

Geophysical exploration for lithological control of arsenic contamination in groundwater in Middle Ganga Plains, India

A hydrogeochemical analysis of water samples in Middle Ganga Plains (MGP) revealed patchy occurrence of arsenic contamination in groundwater with high spatial variability. An integrated study consists of hydrochemical, 2-d DC resistivity and IP chargeability, and 1-d transient electromagnetic measurements (TEM) was carried out in the Ganga–Son interfluves region, which helped in identifying the contrast in lithological set up in the form of low resistivity (10–25 Ωm) and high chargeability (5–20 mV/V) clay deposits between the arsenic contaminated and arsenic free aquifers. It revealed that the clay acts as controlling factor to the arsenic contamination in the groundwater regime. Knowledge of impermeable clay barrier helps in reducing the uncertainties that exist in the hypothesis of arsenic in groundwater in the MGP, as the clay boundaries inferred from the geophysical interpretations coincide very closely with the boundary of arsenic free and arsenic contaminated groundwater obtained from the water quality analysis.

Arsenic-safe alternate aquifers and their hydraulic characteristics in contaminated areas of Middle Ganga Plain, Eastern India

Arsenic groundwater contamination exceeding 0.05 mg/l affecting the Newer Alluvial tracts of Patna and Bhojpur, the two worst affected districts located in the Middle Ganga Plain in the Bihar state, has been studied The area is underlain by two-tier Quaternary aquifer systems within a depth of 300 m below ground level, separated by a 15-32-m-thick clay/sandy clay aquitard. The upper part (<50 m depth) of the shallow aquifer system is arsenic-contaminated. The deeper aquifer system (lying below 120-130 m depth) exhibits low arsenic load (max 0.0035 mg/l), having hydraulic conductivity between 64.88 and 82.04 m/day. Groundwater in the deeper aquifer occurs under semi-confined to confined condition due to poor hydraulic conductivity of the middle clay (4.7×10(-2)-7.2×10(-3) m/day). Hydraulic head of the deeper aquifer remains close to the surface than the shallow aquifer. The two aquifer systems in the Newer Alluvium are replaced by a thick single aquifer system in the adjoining Older Alluvium, within a depth of 330 m below ground. In the arsenic-contaminated area, deeper aquifer is protected by a middle clay, which may be developed for community drinking water supply by deep tube wells having a yield capacity of 150 m3/h.

Neolithic Settlement Patterns of the Middle Ganga Plain

Neolithic Settlement Patterns of the Middle Ganga Plain

Groundwater arsenic contamination in the Sahibganj district of Jharkhand state, India in the middle Ganga plain and adverse health effects

A detailed study in the Sahibganj district of Jharkhand state in the middle Ganga plain was carried out to determine the severity of groundwater arsenic contamination and related adverse health effects due to chronic arsenic exposure. Arsenic was analyzed by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) in water and biological samples in both contaminated and noncontaminated areas. Health effects in three villages where tubewells (n = 178) were highly contaminated (91, 79.8, and 42% above 10, 50, and 300 µg L−1) were determined. Analyses of a total of 367 biological samples (nail, hair, and urine) from affected villages revealed that an average 88% of samples contained arsenic above normal level. Out of 522 people screened from these three villages, 71 were registered with arsenical skin lesions. A case involving arsenical skin lesions resulting in cancer was noted during the study. A representative histopathological picture of skin biopsy was presented. Out of 40 children examined, nine were registered with arsenical skin lesions. A child of 18 months drinking arsenic concentration water 1150 µg L−1 displayed arsenical skin lesions, indicating arsenical skin lesions may appear earlier if arsenic concentration is high in drinking water. Different clinical and electrophysiological neurological features and abnormal quantitative sensory perception thresholds were noted amongst patients. Provision of safe water, better nutrition, and proper awareness about the arsenic danger to exposed population may save lives and avoid sufferings.

Role of Quaternary stratigraphy on arsenic-contaminated groundwater from parts of Middle Ganga Plain, UP–Bihar, India

Late Quaternary stratigraphy and sedimentation in the Middle Ganga Plain (MGP) (Uttar Pradesh–Bihar) have influenced groundwater arsenic contamination. Arsenic contaminated aquifers are pervasive within narrow entrenched channels and flood plains (T0-Surface) of fine-grained grey to black coloured argillaceous organic rich Holocene sediments (Newer Alluvium). Contaminated aquifers are often located close to distribution of abandoned or existing channels and swamps. The Pleistocene Older Alluvium upland terraces (T2-Surface) made up of oxidized yellowish brown sediments with calcareous and ferruginous concretions and the aquifers within it are free of arsenic contamination. MGP sediments are mainly derived from the Himalaya with minor inputs from the Peninsular India. The potential source of arsenic in MGP is mainly from the Himalaya. The contaminated aquifers in the Terai belt of Nepal are closely comparable in nature and age to those of the MGP. Arsenic was transported from disseminated sources as adsorbed on dispersed phases of hydrated-iron-oxidea and later on released to groundwater mainly by reductive dissolution of hydrated-iron-oxide and corresponding oxidation of organic matter in aquifer. Strong reducing nature of groundwater is indicated by high concentration of dissolved iron (11.06 mg/l). Even within the arsenic-affected areas, dugwells are found to be arsenic safe due to oxyginated nature.

Arsenic groundwater contamination and its health effects in the state of Uttar Pradesh (UP) in upper and middle Ganga plain, India: A severe danger

This communication presents results of our 2-year survey on groundwater arsenic contamination in three districts Ballia, Varanasi and Gazipur of Uttar Pradesh (UP) in the upper and middle Ganga plain, India. Analyses of 4780 tubewell water samples revealed that arsenic concentrations in 46.5% exceeded 10 μg/L, in 26.7%, 50 μg/L and in 10% 300 μg/L limits. Arsenic concentrations up to 3192 μg//L were observed. The age of tubewells (n=1881) ranged from less than a year to 32 years, with an average of 6.5 years. Our study shows that older tubewells had a greater chance of contamination. Depth of tubewells (n=3810) varied from 6 to 60.5 m with a mean of 25.75 m. A detailed study in three administrative units within Ballia district, i.e. block, Gram Panchayet, and village was carried out to assess the magnitude of the contamination. Before our survey the affected villagers were not aware that they were suffering from arsenical toxicity through contaminated drinking water. A preliminary clinical examination in 11 affected villages (10 from Ballia and 1 from Gazipur district) revealed typical arsenical skin lesions ranging from melanosis, keratosis to Bowens (suspected). Out of 989 villagers (691 adults, and 298 children) screened, 137 (19.8%) of the adults and 17 (5.7%) of the children were diagnosed to have typical arsenical skin lesions. Arsenical neuropathy and adverse obstetric outcome were also observed, indicating severity of exposure. The range of arsenic concentrations in hair, nail and urine was 137–10,900, 764–19,700 μg/kg, and 23–4030 μg/L, respectively. The urine, hair and nail concentrations of arsenic correlated significantly (r=0.76, 0.61, and 0.55, respectively) with drinking water arsenic concentrations. The similarity to previous studies on arsenic contamination in West Bengal, Bihar and Bangladesh indicates that people from a significant part of the surveyed areas in UP are suffering and this will spread unless drives to raise awareness of arsenic toxicity are undertaken and an arsenic safe water supply is immediately introduced.

Arsenic groundwater contamination in Middle Ganga Plain, Bihar, India: a future danger?

The pandemic of arsenic poisoning due to contaminated groundwater in West Bengal, India, and all of Bangladesh has been thought to be limited to the Ganges Delta (the Lower Ganga Plain), despite early survey reports of arsenic contamination in groundwater in the Union Territory of Chandigarh and its surroundings in the northwestern Upper Ganga Plain and recent findings in the Terai area of Nepal. Anecdotal reports of arsenical skin lesions in villagers led us to evaluate arsenic exposure and sequelae in the Semria Ojha Patti village in the Middle Ganga Plain, Bihar, where tube wells replaced dug wells about 20 years ago. Analyses of the arsenic content of 206 tube wells (95% of the total) showed that 56.8% exceeded arsenic concentrations of 50 micro g/L, with 19.9% > 300 micro g/L, the concentration predicting overt arsenical skin lesions. On medical examination of a self-selected sample of 550 (390 adults and 160 children), 13% of the adults and 6.3% of the children had typical skin lesions, an unusually high involvement for children, except in extreme exposures combined with malnutrition. The urine, hair, and nail concentrations of arsenic correlated significantly (r = 0.72-0.77) with drinking water arsenic concentrations up to 1,654 micro g/L. On neurologic examination, arsenic-typical neuropathy was diagnosed in 63% of the adults, a prevalence previously seen only in severe, subacute exposures. We also observed an apparent increase in fetal loss and premature delivery in the women with the highest concentrations of arsenic in their drinking water. The possibility of contaminated groundwater at other sites in the Middle and Upper Ganga Plain merits investigation.

Development of Regional Flood Frequency Relationships Using L-moments for Middle Ganga Plains Subzone 1(f) of India

In this study, screening of the data has been carried out basedon the discordancy measure (Di) in terms of the L-moments. Homogeneity of the region has been tested using the L-moments based heterogeneity measure, H. For computing the heterogeneity measure H, 500 simulations were carried out using the four parameter Kappa distribution. Based on this test, it has been observed that the data of 8 out of 11 bridge sites constitute ahomogeneous region. Hence, the data of these 8 sites have been used in this study. Catchment areas of these 8 sites vary from 32.89 to 447.76 km2 and their mean annual peak floods varyfrom 24.29 to 555.21 m3 s-1. Comparative regional floodfrequency analysis studies have been carried out using the various L-moments based frequency distributions viz. Extreme value (EV1), General extreme value (GEV), Logistic (LOS), Generalized logistic (GLO), Normal (NOR), Generalized normal (GNO), Uniform (UNF), Pearson Type-III (PE3), Exponential (EXP),Generalized Pareto (GPA), Kappa (KAP), and five parameter Wakeby(WAK). Based on the L-moment ratio diagram and ∣ Zidist ∣–statistic criteria, GEV distribution has been identified as the robust distribution for the study area. For estimation of floods of various return periods for gauged catchments of the study area, regional flood frequency relationship has been developed using the L-moments based GEV distribution. Also, for estimation of floods of desiredreturn periods for ungauged catchments, regional flood frequencyrelationship has been developed by coupling the regional flood frequency relationship with the regional relationship between mean annual maximum peak flood and catchment area.

Geomorphic evolution of a part of Middle Ganga Plain, Bihar: A case study using remote sensing data

An insight into the geomorphic evolution of any area can be obtained by detailed landform mapping. In the present study, an area in the Middle Ganga Plain has been selected for the study using mainly remote sensing data. Various fluvial landforms have been mapped and the changes in planform of rivers over approximately 50 years have been evaluated. Both fluvial processes and tectonic activities are considered to have collectively influenced the migration of the rivers in this region. Digital enhancements of Landsat MSS and TM data are found to be quite useful in identification and mapping of subtle fluvial palaeofeatures. The present study demonstrates the utility of remote sensing in examining the geomorphic evolution of the area.

The role of multispectral imagery in elucidation of recent channel pattern changes in middle ganga plain

The mapability of Landsat images has opened up a new potentiality for study of channel pattern changes which was earlier not so easy due to nonavailability of suitable evidences at different timespans. Middle Ganga plain covering largely the northern part of Bihar and parts of eastern Uttar Pradesh is in a slate of perpetual flux due to large scale channel migration and avulsion resulting in devastating floods. Mosaic of three Landsat images has helped to study the channel changes which have occurred since 1935. The course of the river Ganga has beeh digitised along a basal line and two dimensional coordinates are taken at as many as more than fifty sample points for studying the magnitude and direction of channel changes during 1935–1975 period. The analysis shows that the main multiple channel river Ganga is under the huge hydrostatic thrust to be shifted towards south of its basin annually at a very high rate of 100 Meter per year all along the course except at its upstream near Ghazipur and at Monghyr where the shifting is towards north. The northward bend at Monghyr may be due to the presence of the Precambrian outliers here. For the multi-and single channelld tributaries of Ganga in channel behaviour is mainly in three directions—the lower water channels in the floodplain of Ganga are shifting to the south in conformity with that of their parent stream, the tributaries in Gogra-Gandak doab are shifting towards east but the shifting of the Kosi-Mahananda group of tributaries in the eastern part of the basin is towards west These channel pattern changes thus known at the interregional scale from the Landsat images may further be integrated with the study in hydrogeomorphology and their pertinent environmental impact.

Economic Regions of Chota Nagpur, Bihar, India

(1953). Economic Regions of Chota Nagpur, Bihar, India. Economic Geography: Vol. 29, No. 3, pp. 216-250.