A study of groundwater irrigation water quality in south-central Bangladesh: a geo-statistical model approach using GIS and multivariate statistics  

作　　者：M.Atikul Islam Md.Mostafizur Rahman Md.Bodrud-Doza Md.Iftakharul Muhib Mashura Shammi Anwar Zahid Yeasmin Akter Masaaki Kurasaki 

机构地区：[1]Department of Chemistry, Hajee Mohammad Danesh Science and Technology University [2]Department of Environmental Sciences, Jahangirnagar University [3]Graduate School of Environmental Science, Hokkaido University [4]Department of Environmental Pollution and Process Control,Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences [5]Groundwater Hydrology, Bangladesh Water Development Board [6]Department of Chemistry, University of Chittagong

出　　处：《Acta Geochimica》2018年第2期193-214,共22页地球化学学报（英文）

基　　金：supported by the project entitled ‘‘Establishment of monitoring network and mathematical model study to assess salinity intrusion in groundwater in the coastal area of Bangladesh due to climate change’’ implemented by Bangladesh Water Development Board;sponsored by Bangladesh Climate Change Trust Fund, Ministry of Environment and Forest

摘　　要：Southern Bangladesh＇s irrigation and drinking water is threatened by saline intrusion. This study aimed to establish an irrigation water quality index （IWQI） using a geostatistical model and multivariate indices in Gopalganj district, south-central Bangladesh. Groundwater samples were taken randomly （different depths） in two seasons （wet-monsoon and dry-monsoon）. Hydrochemical analysis revealed groundwater in this area was neutral to slightly alkaline and dominating cations were Na^＋, Mg^2＋, and Ca^2＋ along with major anions Cl^- and HCO3^-. Principal component analysis and Gibbs plot helped explain possible geochemical processes in the aquifer. The irrigation water evaluation indices showed： electrical conductivity （EC） 〉750 μS/cm, moderate to extreme saline; sodium adsorption ratio （SAR）, excellent to doubtful; total hardness （TH）, moderate to very hard; residual sodium bicarbonate, safe to marginal; Kelly＇s ratio 〉1; soluble sodium percentage （SSP）, fair to poor; magnesium adsorption ratio, harmful for soil; and IWQI, moderate to suitable. In addition, the best fitted semivariogram for IWQI, EC, SAR, SSP, and TH confirmed that most parameters had strong spatial dependence and others had moderate to weak spatial dependence. This variation might be due to the different origin/sources of major contributing ions along with the influence of variable river flow and small anthropogenic contributions. Furthermore, the spatial distribution maps for IWQI, EC, SSP, and TH during both seasons confirmed the influence of salinity from the sea; low-flow in the major river system was the driving factor of overall groundwater quality in the study area. These findings may contribute to management of irrigation and/or drinking water in regions with similar groundwater problems.Southern Bangladesh's irrigation and drinking water is threatened by saline intrusion. This study aimed to establish an irrigation water quality index(IWQI) using a geostatistical model and multivariate indices in Gopalgan district, south-central Bangladesh. Groundwater samples were taken randomly(different depths) in two seasons(wet-monsoon and dry-monsoon). Hydrochemical analysis revealed groundwater in this area was neutral to slightly alkaline and dominating cations were Na^+, Mg^(2+), and Ca^(2+) along with major anions Cl-and HCO^(3-). Principa component analysis and Gibbs plot helped explain possible geochemical processes in the aquifer. The irrigation wate evaluation indices showed: electrical conductivity(EC)[750 l S/cm, moderate to extreme saline; sodium adsorption ratio(SAR), excellent to doubtful; total hard ness(TH), moderate to very hard; residual sodium bicar bonate, safe to marginal; Kelly's ratio [1; soluble sodiumpercentage(SSP), fair to poor; magnesium adsorption ratio,harmful for soil; and IWQI, moderate to suitable. In addition, the best fitted semivariogram for IWQI, EC, SAR,SSP, and TH confirmed that most parameters had strong spatial dependence and others had moderate to weak spatial dependence. This variation might be due to the different origin/sources of major contributing ions along with the influence of variable river flow and small anthropogenic contributions. Furthermore, the spatial distribution maps for IWQI, EC, SSP, and TH during both seasons confirmed the influence of salinity from the sea; low-flow in the major river system was the driving factor of overall groundwater quality in the study area. These findings may contribute to management of irrigation and/or drinking water in regions with similar groundwater problems.

关 键 词：SEMIVARIOGRAM Ordinary kriging model Salinity Irrigation water quality index GIS HYDROCHEMISTRY 

分 类 号：X523[环境科学与工程—环境工程]