Analysis of spatio-temporal trend in groundwater elevation data from arsenic affected alluvial aquifers – Case study from Murshidabad district, West Bengal, Eastern India,Journal of Earth System Science

当前位置： X-MOL 学术 › J. Earth Syst. Sci. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Analysis of spatio-temporal trend in groundwater elevation data from arsenic affected alluvial aquifers – Case study from Murshidabad district, West Bengal, Eastern India
Journal of Earth System Science ( IF 1.9 ) Pub Date : 2020-11-11 , DOI: 10.1007/s12040-020-01489-8
Rhitwik Chatterjee , Swetadri Samadder , Debabrata Mondal , Kalyan Adhikari

Abstract

Fluctuation in groundwater level is a time-dependent stochastic process. It is also a function of various inflow and outflow components to and from the hydrologic system concerned. Depth to water level data are measured through a network of observation wells or hydrograph stations to ascertain the degree of fluctuation in groundwater level at the desired scale, on a long-term basis. Basically, these depths to water level data are point measurements, which can be regarded as random variables furnishing changes in groundwater storage over time. The intrinsic in-homogeneity in aquifer materials introduces variations like jumps, trends, and periodicities in such hydrologic time series data. Thus, trending results from certain gradual, natural and/or anthropogenic interventions in the hydrologic environment and analyses of their trends are imperative for assessment of groundwater level scenario in the area of interest. This in turn, is essential for strategic planning and management for exploitation of the precious groundwater resource in the same area. The area of interest in this article, i.e., Murshidabad is one of the nine arsenic affected districts of West Bengal. Here, contamination persist within, shallow, arseniferous, alluvial aquifers, which are otherwise widely exploited for irrigation purposes. According to many researchers working in this area, over-exploitation of groundwater is the root cause for the plummeting water level and the widespread arsenic contamination as well. The present study intends to detect and analyze the trends persisting in the depth to water level data measured over a period from 1996 to 2016, in Murshidabad district of West Bengal, India, amidst its complex and contrasting hydrogeologic set-up and interpret the results in terms of the hydrologic attributes of the Bengal basin as a whole. The non-parametric Mann–Kendall test and the Sen’s slope estimator have been used to identify the linear trend persisting in the time series pre- and post-monsoon groundwater elevation values. The analysis indicates statistically significant decline in water level across the study area especially during the post-monsoon season. This can be attributed to the recharge–discharge disparity within the hydrologic regime; brought through intense pumping over the study area. Its ill effect being particularly observed in the western part of river Bhagirathi. Findings of such study are crucial for assessment of dynamic groundwater resources of the district and subsequently can be utilized as a decision support tool for groundwater management at micro-level.

Research Highlights

Declining trend in ground water level elevation is indicative of startling water crisis over a region; however, assessment of such trend should be performed over a quantitative basis, as; fluctuation in groundwater level is a time-dependent stochastic process.
A well-knit methodology (including RL correction, spatial interpolation of data, analyses and quantification of trend present in the data) needs to be followed by the groundwater managers operating at the micro-level to keep an account of aquifer storage conditions.
Statistically significant declining trend in water level elevation is observed in the Arsenic affected shallow alluvial aquifers, on either sides of river Bhagirathi.Ã
Lack of groundwater replenishment within recoverable recharge, coupled with over extraction causes such drop in groundwater elevation.
To combat similar situation groundwater extraction should be restricted within the limit of sustainability and should not exceed natural recharge potential.

中文翻译：

受砷影响的冲积含水层的地下水高程数据时空趋势分析–来自印度东部西孟加拉邦Murshidabad地区的案例研究

摘要

地下水位的波动是一个随时间变化的随机过程。这也是进出有关水文系统的各种流入和流出成分的函数。通过观察井或水位测量站网络测量水位深度数据，以长期确定地下水位在所需范围内的波动程度。基本上，这些深度到水位数据都是点测量，可以将其视为提供随时间变化的地下水存储量的随机变量。含水层材料的固有非均质性在此类水文时间序列数据中引入了跃变，趋势和周期性等变化。因此，趋势是由一定程度的渐进产生的，水文环境中的自然和/或人为干预措施及其趋势分析对于评估感兴趣地区的地下水位情况势在必行。反过来，这对于在同一地区开采宝贵的地下水资源进行战略规划和管理至关重要。本文的关注区域，即穆尔希达巴德（Murshidabad），是西孟加拉邦受到砷污染的九个地区之一。在这里，污染物在浅，砷，冲积含水层中持续存在，否则将其广泛用于灌溉目的。据该领域的许多研究人员称，地下水的过度开采是水位暴跌和砷污染广泛的根本原因。本研究旨在检测和分析1996年至2016年期间在印度西孟加拉邦Murshidabad地区测得的深度水位数据中持续存在的趋势，该水文地质条件复杂且对比鲜明，并解释了该结果。孟加拉盆地整体的水文属性。非参数Mann-Kendall检验和Sen的斜率估计器已用于识别季风前后地下水位高程时间序列中持续的线性趋势。分析表明，整个研究区域的水位在统计上均显着下降，尤其是在季风后季节。这可以归因于水文情势中的补给与排水差异。通过在研究区域上大量抽水带来。在Bhagirathi河西部尤为明显。此类研究的结果对于评估该地区的动态地下水资源至关重要，因此可以作为微观层面地下水管理的决策支持工具。