Characterisation the relationship of groundwater quality with land use using factor analysis in district Jaipur of Rajasthan Ojha Santosh1,*, Sharma Gunwant1, Machiwal Deepesh2 1Malaviya National Institute of Technology, Jaipur, Rajasthan 2Malaviya National Institute of Technology, Jaipur, Rajasthan 3Central Arid Zone Research Institute (CAZRI), Jodhpur, Rajasthan *Corresponding author email id: santosh16mar@gmail.com
Online Published on 30 March, 2024. Abstract The groundwater quality is deteriorating severely in semi-arid regions of Rajasthan owing to rapid industrialization, rigorous agricultural practices and over-exploitation of groundwater. The widespread application of fertilizers and pesticides; and poor management of land use have indorsed pollutants to infiltrate through unsaturated soil and ultimately reach the underlying unconfined groundwater system. Thus, the quality of the water stored in the aquifers has been considerably affected by land use. The study is aimed to illustrate the relationships between groundwater quality and LULC considering the material properties of unsaturated soil. The study combines 14 groundwater quality parameters sampled from 94 monitoring wells, area percentage of eight LULC categories in the vicinity of 3 Km for these 94 monitoring well locations and thickness of four types of materials in the unsaturated/vadose zone of these wells, based on lithological cross-section of borehole data obtained all through the establishment, using factor analysis considering variability in them. Factor Analysis depicts that eight factors were responsible, being eigen values more than 1.0 with 77.397 per cent of cumulative variability. But, only four factors were considered to avoid the complexity of analysis, which represents 57.558 per cent of cumulative variability. Factor 1 represents 21.138 per cent of the total variability with strong correlation for EC, TDS, Na, HCO3 and fluoride, moderate correlation for chloride and carbonate and the land under fallow land. The blend of EC, TDS, sodium, chloride can be interpreted as salinity factor, occurred due to dissolution of rock materials i.e. schist, mica in the groundwater and over-exploitation of groundwater resources. Factor 2 shows strong correlation for calcium, magnesium, sulphate and total hardness, moderate correlation for potassium and nitrate and the land used for forest land with 20.527 per cent of the total variability. Factor 2 can be designated as alkanity due to agricultural and domestic waste disposal. The findings has also been proven through rock-water interaction dominant factor, controlling groundwater chemistry using Gibb’s diagram and Na-HCO3 and Na-Cl-SO4 hydro-chemical facies acquired by Piper’s diagram. Factors 3 and 4 have shown 8.031and 7.863 percentage of variance, with strong factor loading for built-up land and moderate factor loadings for barren land and gullied/ravenous land and strong factor loadings for fine sand, respectively. These factors were neglected owing to no significant loadings and weak negative loadings. Based on the geographical (spatial) distribution of the factor scores for the first two factors correlating with groundwater quality parameters and land use patterns, it can be concluded that southern and south-eastern portion of district is covered under fallow land due to high salinity and great thickness of clay/silt unsaturated soil and north-eastern part of the district which is confined under forest land, exhibits highest concentration of nitrate and magnesium due to biological nitrate fixation under deciduous forest and proximity with agricultural cropland. It is recommended to prioritize the areas where intensive application of fertilizers and pesticides are being practiced and evaluate the land use practices and new measures like organic fertilizer; need to be adopted to avoid or control groundwater pollution. Top Keywords Groundwater quality, Gibb’s diagram, Hydro-chemical facies, Factor analysis, Variability, Spatial distribution, Factor score. Top |