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Infiltration process, which plays a paramount role in irrigation and drainage systems design, groundwater recharge and contamination evaluation, flood and drought management etc. is often controlled by several factors, among which land use/land cover (LULC) and soil physical properties are the prime factors. These factors lead to significant spatial variability of infiltration process, which poses a serious challenge for hydrologists and water managers. However, studies analyzing spatial variability and influence of both LULC and soil physical properties are scarce. To this end, grid-based infiltration experiments were carried out in a tropical sub-humid region of India to investigate spatial variability of infiltration characteristics, saturated hydraulic conductivity (K sat) as well as to evaluate reliability of seven infiltration models in predicting infiltration behaviour and estimating K sat. Additionally, uncertainty analysis was performed to quantify uncertainties associated with estimated K sat for different LULC and soils. Results indicated that quasi-steady infiltration rate over the study area vary considerably with a majority of the area falling under 'low' and 'medium' infiltration categories. The infiltration process is greatly influenced by macro-pores and relatively low-permeable layers present at varying depths, typical features of lateritic vadose zones in tropical sub-humid regions, rather than its sole dependence on texture and LULC. Further, the Brutsaert model estimates K sat with the highest accuracy and least uncertainty followed by Swartzendruber and Horton models. Except the Brutsaert model, other models are sensitive to a particular LULC. Overall, it is inferred that the Brutsaert and Swartzendruber models are robust and more reliable in predicting infiltration behavior and K sat for the area. Findings of this study including quantification of spatial variability of important soil properties are useful for understanding detailed hydrological processes in the region and thereby, ensuring better planning and management of recurring floods and drought problems of the region.

a b s t r a c tGroundwater quality of Bailadila iron ore mine area has been studied. Groundwater samples were collected from hand pumps, and analysed in order to find out water quality index (WQI) and heavy metal pollution index (HPI). A comprehensive study has been carried out with respect to aluminium (Al ). Seasonal variation in the metal concentration has been assessed in pre-monsoon and post-monsoon seasons. The physio-chemical parameters have been analyzed with standard procedure and instrumental techniques. It is found that a sizeable number of groundwater samples contain iron at toxic level. At few locations, Pb 2+ concentrations are also found higher than permissible limit. Al 3+ , Cr 6+ and Zn 2+ content of groundwater were found to be within the guideline value of World Health Organisation (WHO). The metal concentration of groundwater in Bailadila iron ore mine area follows the trend Fe 2+ > Zn 2+ > Al 3+ > Cr 6+ > Pb 2+ in both pre and post monsoon seasons. The correlation ability of five heavy metals has been selected for the study area and these metals cause eco-toxicology and health hazards to the human being as well as to aquatic biota. The estimation of the concentration of these heavy metals associated element may establish the trend of heavy metals distribution. Monitoring and correlation data show that the quality of groundwater is vulnerable to anthropogenic contamination. The overall results indicate that groundwater quality of Bailadila iron ore mine area and its peripherals is very poor and not safe for human consumption without treatment.

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Vadose zone acts as a controlling agent for recharge and transport of contaminants into aquifers. Hence, for modelling and quantifying flow and transport processes in subsurface environments, hydraulic conductivity (K) of the vadose zone plays an important role. However, given the heterogeneity and anisotropy of subsurface systems, the in-situ measurement of K is a daunting task at a larger scale. The present study was conceived to evaluate the efficacy of salient pedotransfer functions (PTFs) to indirectly estimate the saturated hydraulic conductivity (K s) of a lateritic vadose zone of eastern India. Also, in-situ hydraulic conductivity along with basic soil physical properties was determined in different vadose-zone layers at three locations (bare plot, cultivated field and orchard). Four PTFs [Campbell, Rawls-Brakensiek/Cronican-Gribb (R-B/C-G), and Models 2 and 3 of Rosetta] were selected to estimate K s and their performances were evaluated. Based on the statistical indicators, it is concluded that Model 3 of Rosetta is capable of predicting relatively close values of K s for the lateritic vadose zones to some extent. To generalise the findings of this study, it is recommended that such field-based studies should be carried out at a larger scale in lateritic terrains with varying land use/land cover.