Impacts of climate variability and droughts on groundwater quality in Nawabshah District, Sindh, Pakistan | |
| Author | Sanaullah |
| Call Number | AIT Thesis no.WM-19-39 |
| Subject(s) | Groundwater Quality--Pakistan--Nawabshah District Climatic changes--Pakistan--Nawabshah District Droughts--Pakistan--Nawabshah District |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Nawabshah as arid and semi-arid regions always faces the problem of droughts. Quality of groundwater are changing under the impacts of climate variability. The main goal of this study is to evaluate the impacts on the groundwater quality in the Nawabshah District, Sindh, Pakistan. To achieve this aim, spatial and temporal changes of groundwater has been analyzed, using hydrometric and meteorological data. SPEI index (standardized precipitation Evapotranspiration Index) in 4 Aphrodite gridded data from 1986 to 2015 , and multivariate statistical techniques applied for evaluation of temporal/spatial variations and interpretation of a large complex groundwater-quality data set obtained during monitoring. In SPEI the Thornthwaite equations for estimating evapotranspiration. The results that indicated that the drought showed a non-significant upward trend in the Nawabshah station from 1986 to 2015, and drought events became more serious after the 1987s; the month and season with the most serious drought was May to September, with an average SPEI value of -1.86 and -2.23; the seasons with an increasing drought trend were, summer, and autumn; the most serious drought duration of 20 months in study area, with drought Intensity of -3.14. Ten years (2006 –2015) data set of 9 groundwater quality variables covering 18 monitoring wells observations were treated with different multivariate techniques such as cluster analysis, discriminant analysis (DA) and factor analysis/principal component analysis (FA/PCA). Agglomerative hierarchical CA grouped 18 monitoring wells into three groups (low pollution, moderate pollution, and high pollution) based on their similarity of water quality characteristics. Discriminant analysis showed the best results for data reduction and pattern recognition during both temporal and spatial analysis. Discriminant analysis showed five parameters (Ca+2, Mg+2, Na+, HCO3- and SO4-) affording more than 85% right assignations in temporal analysis, while six parameters (Ca+2, Mg+2, Na+, HCO3- , Cl-, SO4- ) giving 91 % correct assignation in spatial analysis. F.A/PCA, applied to the data sets of the three different groups obtained from cluster analysis, resulted in four, four and three latent factors explaining 76.194, 69.193 and 61.927% of the total variance in water groundwater quality data sets of LP, MP and HP areas, respectively. The varifactors obtained from factor analysis indicate that the parameters responsible for groundwater quality variations are mainly, Dissolution of sodium and gypsum and sodium sulphate mineral can increase the SO4-concentration organic pollution (point source: domestic wastewater) in relatively less polluted areas. Also, the groundwater quality indices for agricultural usages are classified in four classes including, C4-S4 33, C2-S1 28, C3-S2 17, C2-S4 5, C3-S3 5 and C1-S1 12 % of the total aquifer area. Water quality during these droughts was investigated. The pattern and magnitude of the statistically significant responses (r, t-test and p < 0.05) varied among sites, i.e. pre-monsoon Ca, Mg and Na, for post monsoon Cl, EC and TDS at N.Shah-17, for pre monsoon and post monsoon Na and EC at N.Shah-21, In Pre monsoon EC and SO4, In post monsoon SO4 at station-22, We can conclude that data regarding other environmental changes, such as land use, will be needed to further elucidate the response of water quality to droughts. |
| Year | 2019 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Shrestha, Sangam; |
| Examination Committee(s) | Shanmugam, Mohana Sundaram;Asadi, Mohammad Esmaeil; |
| Scholarship Donor(s) | Irrigation Department, Government of Sindh, Pakistan; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2019 |