Articles written in Journal of Earth System Science
Volume 128 Issue 7 October 2019 Article ID 0195 Research Article
Groundwater flow modelling provides the water flow dynamics for the estimation and prediction of groundwater movement and its condition in the aquifer. The modelling helps for the management of the groundwater resources under various hydrological and anthropogenic stresses. In this paper, a modelling exercise was performed using the analytic element method (AEM) and finite difference method (FDM) for the part of Ganga river basin which includes the Varanasi district. Further compression was performed to understand the limitations and benefits of both AEM and FDM based on ease of model development, data requirement and their performances. The groundwater model was developed for the transient state condition based on data for the year 2004–2017. The results show that for most of the observed wells, the difference between the observed head and the simulated head is found in the 90% confidence level. It is found that the AEM does not require a fixed boundary condition which makes the development of the conceptual model less complicated. In the FDM, pumping wells are approximately located and averaged over the cell which becomes a cause of the inaccurate location of the wells. It is found that model development in the AEM is less complicated compared to the FDM. It can be concluded that in some cases AEM-based modelling is more accurate as compared to FDM-based flow modelling. This study can be very helpful for groundwater professionals in deciding the best suitable method for their study area and to avoid the complexity of the model.
Volume 130 All articles Published: 6 October 2021 Article ID 0205 Research article
Excessive water use in the agricultural sector in the Betwa–Dhasan basin of the Bundelkhand region is becoming the cause of irrepressible drawdown in the groundwater level. These changing dynamics are becoming the cause of water scarcity in the basin and increasing difficulty in fulfilling the water demand ofthe area. For incorporating the water-saving agricultural practices in the region, it is essential to have a precise estimation of the crop water productivity (CWP) and evapotranspiration (ET) at the basin scale. In this analysis, the Kharif and Rabi seasons of 2004–2005, 2009–2010, and 2013–2014 have been included.The ET and CWP have been calculated for all the seasons. The MODIS satellite imageries have been used for calculating the ET using the surface energy balance algorithm for land (SEBAL) algorithm. The highest CWP has been recorded as 2.56 kg/m$^3$ for the Rabi season 2014. With the increase in the demand for water for irrigation and agricultural purposes, the groundwater gets depleted. The decadal groundwater Cuctuation map of the Rabi season (2005–2014) shows that groundwater gets depleted by more than 30 m within this period in some of the river basin regions situated in the Jhansi and Tikamgarh districts.
$\bullet$ CWP is more in the Rabi season as compared to the Kharif season.
$\bullet$ The yield also has the same trend as that of CWP.
$\bullet$ Groundwater depleted less in the Kharif season as compared to the Rabi season.
$\bullet$ During the decadal Rabi season (2005–2014), the groundwater depleted most in some of the areas in the Tikamgarh and Jhansi districts.
Volume 131 All articles Published: 16 April 2022 Article ID 0102 Research Article
Analysing the change in water quality parameters along river Ganga at Varanasi, Mirzapur and Ghazipur using Sentinel-2 and Landsat-8 satellite data during pre-lockdown, lockdown and post-lockdown associated with COVID-19
The proper functioning of the river ecosystem has been symbolised by healthy aquatic life. The river Ganga has shown signs of rejuvenation due to lockdown. In this study, an attempt has been made to analyse the change in river water quality using Sentinel-2 and Landsat-8 imageries. The quantitative analysis has been performed for temperature and normalised difference turbidity index (NDTI). The qualitative analysis has been performed for pH, dissolved oxygen (DO) and total suspended solids (TSSs). Ghazipur, Varanasi and Mirzapur stretches have been selected for this study. In the Ghazipur stretch, the river temperature decreased by 7.14% in May 2020 (lockdown period) as compared to May 2019 (1 yearbefore lockdown). Similarly, in the Varanasi stretch, this decrease has been by 8.62%, and in the Mirzapur stretch, this decrease has been by 12.06% in May 2020 compared to May 2019. For the same period, NDTI in the Ghazipur, Varanasi and Mirzapur stretch has been decreased by 0.22, 0.26 and 0.24, respectively. The pH and DO of the river increased, and TSS decreased for the considered time period. The lockdown during the second wave of the coronavirus disease 2019 was not helpful for river rejuvenation. This study elicited how the behaviour of the parameters changed during the lockdown.
$\bullet$ River Ganga becomes much cleaner in the lockdown period (May 2020) compared to the pre-lockdown time.
$\bullet$ In the Mirzapur stretch, the temperature decreased most in May 2020 as compared to May 2019.
$\bullet$ In the Varanasi stretch, there is a maximum variation in the NDTI value in May 2020 in comparison with that of May 2019.
$\bullet$ The most significant task will be to maintain river conditions during post-lockdown similar to that prevailed during lockdown.
$\bullet$ In the second wave COVID-19 lockdown the river again became polluted like the pre-COVID times.
Volume 131, 2022
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