Groundwater faecal pollution observation in parts of Indo-Ganges-Brahmaputra river basin from in-situ measurements and satellite-based observations
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J. Earth Syst. Sci. (2019) 128:44 c Indian Academy of Sciences https://doi.org/10.1007/s12040-019-1087-8 Groundwater faecal pollution observation in parts of Indo-Ganges–Brahmaputra river basin from in-situ measurements and satellite-based observations Srimanti Duttagupta1 , *, Animesh Bhattacharya1,2 , Abhijit Mukherjee1,3 , Siddhartha Chattopadhyay4 , Soumendra Nath Bhanja5 , Soumyajit Sarkar1 , Pragnaditya Malakar3 and Jayanta Bhattacharya1,6 1 School of Environmental Science and Engineering, Indian Institute of Technology, Kharagpur 721 302, India. 2 Public Health Engineering Department, Government of West Bengal, Kolkata 700 001, India. 3 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India. 4 Department of Humanities and Social Sciences, Indian Institute of Technology, Kharagpur 721 302, India. 5 Faculty of Science and Technology, Athabasca University, 1 University Dr, Athabasca, AB T9S 3A3, Canada. 6 Department of Mining Engineering, Indian Institute of Technology, Kharagpur 721302, India. *Corresponding author. e-mail: srimanti.duttagupta@gmail.com MS received 29 November 2018; revised 30 December 2018; accepted 17 January 2019; published online 22 February 2019 More than quarter of underprivileged global population, who lack access to basic sanitation and clean drinking water, live in India. Consequently, every year, millions suffer with enteric diseases from drinking faecal-contaminated groundwater. The UN Sustainable Development Goal lists access to safe water and basic sanitation for all by 2030, as their sixth goal. For the first time, the role of economic improvement on decrease in water-borne faecal pathogens was studied across Indo-Ganges–Brahmaputra river basin (IGB) for almost last three decades, to delineate the long-term improvement trends of groundwater quality across India, as a consequence of development. Long-term temporal (1990–2017) and high-resolution spatial (administrative block scale, n = 2217) datasets of water-borne faecal pathogen concentration in groundwater and satellite-based nightlight (NL) were used to investigate the statistical trends and causal relationships. Linear and nonlinear (Hodrick–Prescott) trend analyses, panel data analyses, Bayesian vector autoregression (VAR) and lead–lag causality (LLC) analyses were performed on aforesaid culled datasets. However, the efficiency of development in alleviating the water quality and public health, and relationship with economic development, has not been well understood. Here, for the first time, using long-term, high-spatial resolution (n = 2217), annual in-situ measurements and multivariate statistical models, we show that the spatially variable groundwater faecal pathogen concentration (FC, 2002–2017, −1.39 ± 0.01%/yr) has been significantly decreased across the basin. In most areas, increasing satellite- based NL plays a significant role (NL, 1992–2013, 3.05 ± 0.01%/yr) in reduction of FC. However, in areas with low literacy rate surpass development. Enhanced decrease of faecal coliform concentration in groundwater possibly signifies the implementation of Clean India Mission since 2014. Keywords. Faecal coliform; nightlight; Indo-Ganges–Brahmaputra basin; sustainable development goal. 1
44 Page 2 of 6 J. Earth Syst. Sci. (2019) 128:44 1. Introduction effect of satellite-based nightlight (NL, 1992–2013) representing economic development on faecal col- Adequate supply of safe and sustainable water iform concentration (FC, 2002–2017) in ground- and access to basic sanitation are fundamental water sources. To establish the hypothesis on a right and basic need for human health. Approx- basin scale, study has been conducted in densely imately, 1.8 billion people are consuming water populated Indo-Ganges basin. This study also having high faecal contamination worldwide, with focuses on effect of population (P , 2001–2013) the majority residing in low- to middle-income and literacy (L, 2001–2013) across the study area countries (Bain et al. 2014). The Sustainable and helps to understand the significant role of Development Goal (SDG) Goal 6 (UN 2017) aims these parameters on the basis of various statistical to increase the access to safe drinking water approaches. for major population across the world (Clasen et al. 2012). It has been observed that 51.6% households across India did not use basic sanita- 2. Methods tion facility. Hence, drinking water for individual household supply problems remain one of the pri- 2.1 Data acquisition and management mary challenges in rural and peri-urban areas in The faecal coliform concentration (FC) data India. The well-being of a society, its development, (MPN/ 100 ml) across IGB have been taken economics health and essential resource availabil- from National Rural Drinking Water Programme ity are intricately related to each other. It is (NRDWP), Ministry of Drinking Water and San- well known that poverty influences the health of itation, Government of India for 2002–2017. We a population in many ways, including exposure have acquired information of faecal coliform dis- to transmitting diseases, food and water insecu- solved in groundwater from ∼900, 000 locations for rity, and lack of access to basic sanitation and more than one decade. These data points have been water availability. Furthermore, inadequate trans- averaged and upscaled to administrative units (n = port of human excreta to adjacent groundwater 2217). Night-time light (NL) data have been con- due to improper sanitation structure is observed sidered as economic development factors. Annual among poverty-stricken populations, leading to (1992–2013, available at
J. Earth Syst. Sci. (2019) 128:44 Page 3 of 6 44 analysis (Hodrick and Prescott 1997). This study have applied possible statistical tests for data involves panel data analysis to account individual filtration in order to upscale it from individual heterogeneity. Panel data refer to sets that con- data location to administrative unit scale. We have sist of both time and series and cross-sectional estimated standard error for each dataset (Gan- data (Borenstein et al. 2010). In this study, fixed- domi and Haider 2015). Errors associated with FC, effect and random-effect panel data have been used. NL, P and L have been determined by estimat- It is assumed that the error component and the ing the standard deviation from the mean. Error X’s are uncorrelated. Random-effect calculation is estimation has been calculated by the following advantageous as time invariant variables can be equation: included (Torres-Reyna 2007). Lead–lag causality √ Standard error (SE) = δ/ n, (1) (LLC) test has been conducted for faecal coliform and NL to understand the lead–lag effect of NL on where δ is the standard deviation and n is the faecal pollution. number of observations. 3. Results and discussion 2.4 Assumptions and uncertainty 3.1 Spatio-temporal trend of faecal coliform There are several missing data in the archived concentration in groundwater dataset obtained from the government organisa- tion. Different datasets used in this study were FC has been decreased about 79.31% from 2002 compared for mutually available duration. We (∼23.7MPN/100 ml) to 2017 (∼4MPN/100 ml) (a) Indo-Ganges Brahmaputra (IGB) river basin (b) HR RJ UP AS BR Clean India Mission Implementation of JK RJ – Rajasthan WB UP – Uttar Pradesh BR- Bihar JK-Jharkhand CG India WB-West Bengal AS-Assam HR-Haryana CG-Chattisgarh Decrease in faecal coliform concentration in Indo-Ganges Brahmaputra basin groundwater (%) 60-70 50-60 (IGB) Nightlight anomalies >90 70-90 90 70-90 60-70 50-60
44 Page 4 of 6 J. Earth Syst. Sci. (2019) 128:44 across India. The HP analyses show declining 3.2 Spatio-temporal trends of socio-economic faecal coliform concentration trends from 2002 development and population to 2009 with FC decrease at the rate of 1.9 ± 0.003%/yr and increase as 1.3 ± 0.02%/yr from Spatial trend of NL showed an overall increasing 2009 to 2011 (figure 1). Since 2014, it has been trend from 1992 to 2013 (figure 1). It has been observed that faecal coliform concentration trends observed that NL has been increased about were found to be decreasing at 2.47 ± 0.05%/yr 50.04% (2.38 ± 0.03%/yr) from the base year (figure 1). The enhanced decrease of faecal coliform 1992 till 2013 for 2217 blocks. Spatial map of concentration in groundwater has been observed NL (figure 1) showed that 1430 blocks improved due to possible effect of Clean India Mission 80 to >90% among 2217 blocks. A total of 531 or Swachh Bharat mission (figure 1b) (Swachh blocks showed improvement of 60–80% and around Bharat Mission 2017). About 1100 blocks showed 256 blocks showed moderate increase in NL more than 90% cumulative improvement for FC (∼50%). within the study period (highly improved), with Population (P ) and literacy rate (L) have another ∼150 units having improvement between been retrieved from 2001 to 2013 for 2217 blocks 70% and 90% (improved) and ∼700 units hav- (figure 2). The percentage decadal growth of ing 50% and 70% (moderately improved; figure 1). population during 2001–2013 was about 83.9%. However, ∼200 units have 90 70-90 60-70 (b) 50-60 90 70-90 60-70 50-60
J. Earth Syst. Sci. (2019) 128:44 Page 5 of 6 44 Figure 3. Colour map showing (a) the correlation between faecal coliform, nightlight, population and literacy rate and (b) lead–lag correlation across IGB basin between 1992 and 2013. 3.3 Influence of economic development on 4. Conclusion water quality A better knowledge of the prevalence, ecology and To understand the impact of NL, P and L on distribution of faecal contamination in drinking FC (2002–2013) for the entire study region, we water source could be an important initiative for have regressed the data with fixed-effect panel development of strategies to reduce public health data model. A significant impact of both NL and concern. Most of the potable water samples exceed L on FC was observed (the coefficient associated the standard permissible limit of faecal coliform with NL, βNL = −0.02 with t-statistic = −2.05 concentration in rural regions. Suitable environ- [P < 0.01] and L, βL = −0.003, t-statistic = −2.45 mental condition is the primary reason for faecal [P < 0.01]), suggesting FC improves with the incre- coliform growth. As per the study, it has been ase in NL and L. But P showed a significant observed that the area with highest population positive impact on FC (the coefficient associated density decreases the quality of water. Excessive with NL, βP = 0.001 with t-statistic = 2.34). FC population and slums is an intricate problem which improves with NL and L in highly and improved is reflected on all life aspects in low-income coun- region (βNL = −0.91, t-statistic = −4.05 [P < 0.01]; tries like India. It has been reflected through βL = − 0.004, t-statistic = −5.19 [P < 0.01]; βP = results that faecal coliform concentration in urban 0.06, t-statistic = 2.32 [P < 0.01] for urban areas and peri-urban areas is influenced by popula- and βNL = − 0.4, t-statistic = −3.02 [P < 0.01]; tion, whereas literacy rate and NL as a proxy of βL =−0.03, t-statistic = −2.84 [P < 0.01]; βP = economic development showed an influential role 0.01, t-statistic = 1.07 [P < 0.01] for peri-urban in faecal pollution reduction across IGB. Micro- areas). Population does not show a significant bial pollution cannot depend only upon natural impact on faecal coliform decrease across IGB; parameters; it has to be influenced by other socio- however, in urban areas, population increase pos- economic developmental parameters. sibly influences increase of faecal pollution into We have used spatio-temporal patterns and groundwater (figure 3). Faecal pollution has high- multivariate statistical models to show the relation- est effect in 1-year lag (r = 0.94), and it decreases ship between socio-economic development and fae- over time (r = −0.6; figure 3). cal coliform concentration. Results show long-term
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