Browsing by Author "Yadav, Basant"
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Item Open Access Assessment of LNAPL in subsurface under fluctuating groundwater table using 2D sand tank experiments(American Society of Civil Engineers, 2019-06-24) Gupta, Pankaj Kumar; Yadav, Basant; Yadav, Brijesh KumarThe focus of this study was to investigate the fate and transport of toluene, a light nonaqueous-phase liquids (LNAPLs) in the subsurface region under dynamic groundwater table conditions. A series of experiments were conducted using two-dimensional (2D) sand tank setup having dimensions 125×90×10 cm 125×90×10 cm (L×H×W L×H×W ) and integrated with an auxiliary column of inner diameter 14 cm and height 120 cm. Initially, a steady-state flow and LNAPL transport experiment was conducted under stable groundwater table condition. Thereafter, three groundwater table fluctuation experiments were conducted on a rising and falling groundwater table in 2, 4, and 8 h to maintain rapid, general, and slow fluctuation conditions, respectively. The pure phase of toluene was injected at a rate of 1 mL/min 1 mL/min for a total duration of 5 min. Soil-water and soil-vapor samples were periodically collected and analyzed for toluene concentrations. Later, the representation of the 2D sand tank setup was numerically simulated to obtain the response of flow and the LNAPL transport under varying groundwater table conditions. Analysis of the results shows that a large LNAPL pool area (250 cm 2 250 cm2 ) develops under rapidly fluctuating groundwater conditions, which significantly enhances the dissolution rate and contributes to a high concentration of dissolved LNAPLs at the receiving receptors. Estimated values of Sherwood and Peclet numbers show that the dissolution rates were highly affected by groundwater table dynamics, which may cause loss of pure-phase pollutant mass around the pollutant source. The concentration isolines of toluene show that the transport of dissolved LNAPL plumes was also comparatively fast in the case of rapidly fluctuating groundwater. A high biodegradation rate was observed in plume regions having concentration ranges of 140–160 ppm, while it decreases in plume regions having very high (>160 ppm >160 ppm ) and low concentrations (<140 ppm <140 ppm ) of dissolved LNAPL. In the sand tank, microbial growth was found to increase as the plume moved away from the LNAPL pool toward a low gradient, which intensifies the detrimental impact of toluene on the survival of indigenous microorganisms near the LNAPL pool. The results of this study may help in implementing effective remediation techniques to decontaminate LNAPL polluted sites under fluctuating groundwater table conditions, especially in (semi)-arid coastal aquifers.Item Open Access Assessment of traditional rainwater harvesting system in barren lands of a semi-arid region: a case study of Rajasthan (India)(Elsevier, 2022-06-25) Yadav, Basant; Patidar, Nitesh; Sharma, Anupma; Panigrahi, Niranjan; Sharma, Rakesh K.; Loganathan, V.; Krishan, Gopal; Singh, Jaswant; Kumar, Suraj; Parker, AlisonStudy region Dudu station, Rajasthan, India Study focus Rainwater harvesting can be used as a method to recharge aquifers. This can happen with a variety of scales and technologies. One such example is shallow infiltration ponds (Chaukas) which recharge groundwater and increase soil moisture facilitating pastureland development. A HYDRUS-1D model was used to estimate potential groundwater recharge. The model was calibrated using field data from 2019 and validated using data from 2020. The time series of Normalized Difference Vegetation Index (NDVI) was derived at annual scale to assess changes in the vegetation cover. New hydrological insights for the region The modeling revealed that an additional 5% of the rainfall depth was being recharged into the groundwater. In addition, the additional soil moisture was allowing natural grass cover to develop, which could be used by the local community as pastureland. These twin benefits that the local communities are realizing could be scaled up beyond Dudu, to India, and worldwide, as many regions have barren land that is slightly sloping, together with permeable soils, which are the only conditions for the construction of Chaukas. These Chauka systems have helped in sustainable water resources management in these water-stressed regions and the additional livelihood support through developed pastures for animal husbandry.Item Open Access Ensemble modelling framework for groundwater level prediction in urban areas of India(Elsevier, 2019-11-24) Yadav, Basant; Gupta, Pankaj Kumar; Patidar, Nitesh; Himanshu, Sushil KumarIndia is facing the worst water crisis in its history and major Indian cities which accommodate about 50% of its population will be among highly groundwater stressed cities by 2020. In past few decades, the urban groundwater resources declined significantly due to over exploitation, urbanization, population growth and climate change. To understand the role of these variables on groundwater level fluctuation, we developed a machine learning based modelling approach considering singular spectrum analysis (SSA), mutual information theory (MI), genetic algorithm (GA), artificial neural network (ANN) and support vector machine (SVM). The developed approach was used to predict the groundwater levels in Bengaluru, a densely populated city with declining groundwater water resources. The input data which consist of groundwater levels, rainfall, temperature, NOI, SOI, NIÑO3 and monthly population growth rate were pre-processed using mutual information theory, genetic algorithm and lag analysis. Later, the optimized input sets were used in ANN and SVM to predict monthly groundwater level fluctuations. The results suggest that the machine learning based approach with data pre-processing predict groundwater levels accurately (R > 85%). It is also evident from the results that the pre-processing techniques enhance the prediction accuracy and results were improved for 66% of the monitored wells. Analysis of various input parameters suggest, inclusion of population growth rate is positively correlated with decrease in groundwater levels. The developed approach in this study for urban groundwater prediction can be useful particularly in cities where lack of pipeline/sewage/drainage lines leakage data hinders physical based modelling.Item Open Access Estimation of Groundwater Recharge in Semi-Arid Regions under Variable Land Use and Rainfall Conditions.(Cranfield University, 2020-09-17 16:47) Yadav, Basant; Parker, Alison; Le Corre Pidou, Kristell; Campo Moreno, PabloSoil water balance analysis and recharge estimation for a semi-arid region of Lapodiya watershed in 2019-20.Item Open Access Estimation of groundwater recharge in semiarid regions under variable land use and rainfall conditions: a case study of Rajasthan, India(PLOS (Public Library of Science), 2023-03-22) Yadav, Basant; Parker, Alison; Sharma, Anupma; Sharma, Rakesh; Krishan, Gopal; Kumar, Suraj; Le Corre Pidou, Kristell; Campo Moreno, PabloIn the semiarid regions of India, the annual rainfall is very low (~650 mm) and erratic; hence groundwater recharge is vital to support crops, especially in the winter season. For groundwater budgeting it is essential to consider how groundwater recharge is affected by both land-use and rainfall distribution. This study used a soil water balance approach, considering hydrological, meteorological, hydrogeological and crop information to understand the recharge process in semiarid regions. The approach was used at a sub-watershed scale where farmers grow rainfed and irrigated crops. Delayed recharge response on the water table was considered to estimate actual recharge, which closely matches the observed water levels in the field. The recharge estimated in rainfed agricultural lands, rainfed-irrigated agricultural lands, and barren lands was 29%, 17%, and 31% of the total inflow.Item Open Access Evaluation of best management practices for sediment and nutrient loss control using SWAT model(Elsevier, 2019-05-08) Himanshu, Sushil Kumar; Pandey, Ashish; Yadav, Basant; Gupta, AnkitThe intensive study of an individual watershed is required to develop effective and efficient watershed management plans. Identification of critical erosion-prone areas of the watershed and implementation of best management practices (BMPs) is necessary to control the watershed degradation by reducing the sediment and nutrient losses. The present study evaluates and recommends the BMPs in an agriculture-based Marol watershed (5092 km2) of India, using a hydrologic model, Soil and Water Assessment Tool (SWAT). After successful calibration and validation, the model simulated daily/monthly discharge and sediment were found satisfactory throughout the simulation period. The model was then applied with a calibrated set of parameters for evaluating the effectiveness of various management practices for sediment and nutrient loss control. Keeping in mind the existing agricultural practices, socio-economic aspects and geography of the study area, the management practices were focused on four crops (Maize, Rice, Soybeans and Ground nut), three fertilization levels (high, medium and low), four tillage treatments (Field cultivator, Conservation tillage, Zero tillage and Mould board plough), and two conservation operations (Contour farming and Filter strips). The simulated annual average sediment yield from the watershed was found to be 12.2 t.ha−1yr−1. The water balance analysis revealed that, the evapo-transpiration is predominant over the watershed (approximately 46.3% of the annual average rainfall). Reduction in sediment yield and nutrient loss was observed with alternate cropping treatments of Groundnut and Soybean, as compared to Paddy and Maize cultivation. Overall, based on simulated results, the field cultivator tillage practice and conservation practices viz., contour farming and filter strips, could be adopted to reduce sediment yield and nutrient losses in the critical sub-watersheds of the study area and in other watersheds with similar hydro-climatic conditions.Item Open Access Leakage of CO2 from geological storage and its impacts on fresh soil–water systems: a review(Elsevier, 2020-03-03) Gupta, Pankaj Kumar; Yadav, BasantLeakage of CO2 from the geological storage is a serious issue for the sustainability of the receiving fresh soil–water systems. Subsurface water quality issues are no longer related to one type of pollution in many regions around the globe. Thus, an effort has been made to review studies performed to investigate supercritical CO2 (scCO2) and CO2 enrich brine migration and it's leakage from geological storage formations. Further, the study also reviewed it's impacts on fresh soil–water systems, soil microbes, and vegetation. The first part of the study discussed scCO2/CO2 enrich brine migration and its leakage from storage formations along with it's impact on pore dynamics of hydrological regimes. Later, a state-of-the-art literature survey has been performed to understand the role of CO2–brine leakage on groundwater dynamics and its quality along with soil microbes and plants. It is observed in the literature survey that most of the studies on CO2–brine migration in storage formations reported significant CO2–brine leakage due to over-pressurization through wells (injections and abandoned), fracture, and faults during CO2 injection. Thus, changes in the groundwater flow and water table dynamics can be the first impact of the CO2–brine leakage. Subsequently, three major alterations may also occur—(i) drop in pH of subsurface water, (ii) enhancement of organic compounds, and (iii) mobilization of metals and metalloids. Geochemical alteration depends on the amount of CO2 leaked and interactions with host rocks. Therefore, such alteration may significantly affect soil microbial dynamics and vegetation in and around CO2 leakage sites. In-depth analysis of the available literature fortifies that a proper subsurface characterization along with the bio-geochemical analysis is extremely important and should be mandatory to predict the more accurate risk of CO2 capture and storage activities on soil–water systems.Item Open Access River discharge simulation using variable parameter McCarthy–Muskingum and wavelet-support vector machine methods(2018-09-28) Yadav, Basant; Mathur, ShashiIn this study, an extended version of variable parameter McCarthy–Muskingum (VPMM) method originally proposed by Perumal and Price (J Hydrol 502:89–102, 2013) was compared with the widely used data-based model, namely support vector machine (SVM) and hybrid wavelet-support vector machine (WASVM) to simulate the hourly discharge in Neckar River wherein significant lateral flow contribution by intermediate catchment rainfall prevails during flood wave movement. The discharge data from the year 1999 to 2002 have been used in this study. The extended VPMM method has been used to simulate 9 flood events of the year 2002, and later the results were compared with SVM and WASVM models. The analysis of statistical and graphical results suggests that the extended VPMM method was able to predict the flood wave movement better than the SVM and WASVM models. A model complexity analysis was also conducted which suggests that the two parameter-based extended VPMM method has less complexity than the three parameter-based SVM and WASVM model. Further, the model selection criteria also give the highest values for VPMM in 7 out of 9 flood events. The simulation of flood events suggested that both the approaches were able to capture the underlying physics and reproduced the target value close to the observed hydrograph. However, the VPMM models are slightly more efficient and accurate, than the SVM and WASVM model which are based only on the antecedent discharge data. The study captures the current trend in the flood forecasting studies and showed the importance of both the approaches (physical and data-based modeling). The analysis of the study suggested that these approaches complement each other and can be used in accurate yet less computational intensive flood forecasting.Item Open Access Scaling up indigenous rainwater harvesting: a preliminary assessment in Rajasthan, India(MDPI, 2023-05-27) Rawat, Akanksha; Panigrahi, Niranjan; Yadav, Basant; Jadav, Kartik; Mohanty, Mohit Prakash; Khouakhi, Abdou; Knox, Jerry W.Rainwater harvesting (RWH) has the potential to enhance the sustainability of ground and surface water to meet increasing water demands and constrained supplies, even under a changing climate. Since arid and semi-arid regions frequently experience highly variable spatiotemporal rainfall patterns, rural communities have developed indigenous RWH techniques to capture and store rainwater for multiple uses. However, selecting appropriate sites for RWH, especially across large regions, remains challenging since the data required to evaluate suitability using critical criteria are often lacking. This study aimed to identify the essential criteria and develop a methodology to select potential RWH sites in Rajasthan (India). We combined GIS modeling (multicriteria decision analysis) with applied remote sensing techniques as it has the potential to assess land suitability for RWH. As assessment criteria, spatial datasets relating to land use/cover, rainfall, slope, soil texture, NDVI, and drainage density were considered. Later, weights were assigned to each criterion based on their relative importance to the RWH system, evidence from published literature, local expert advice, and field visits. GIS analyses were used to create RWH suitability maps (high, moderate, and unsuited maps). The sensitivity analysis was also carried out for identified weights to check the inadequacy and inconsistency among preferences. It was estimated that 3.6%, 8.2%, and 27.3% of the study area were highly, moderately, and unsuitable, respectively, for Chauka implementation. Further, sensitivity analysis results show that LULC is highly sensitive and NDVI is the least sensitive parameter in the selected study region, which suggests that changing the weight of these parameters is more likely to decide the outcome. Overall, this study shows the applicability of the GIS-based MCDA approach for up-scaling the traditional RWH systems and its suitability in other regions with similar field conditions, where RWH offers the potential to increase water resource availability and reliability to support rural communities and livelihoods.