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Groundwater flow modeling was carried out to assess current and to project future groundwater scenarios in highly populated and water stressed region of Ganges sub-basin. Both the urban and rural densely populated areas of Ganges sub-basin was selected to capture the groundwater usage patterns in these watersheds. The groundwater system geologically consists of sand and clay layers. However, the layers are not stratified and has highly variable thicknesses and at places various layers disappears. Therefore, a 3D model was prepared so that variability in the vertical direction is also taken care. The study area modeled is divided into grids with 37 rows and 37 columns with 1 km size. The month of June 2016 was taken to perform the steady-state simulation as June has the lowest groundwater levels as well as the minimum stress on the aquifer. Subsequently the Transient state calibration was carried out from June 2016 to November 2018. A good match is obtained between calculated and observed heads in steady state conditions after a rigorous calibration with RMS error as 1.822 m. The sensitivity analysis of the model shows that the model is more sensitive to input parameters like recharge and hydraulic conductivity. The prediction scenarios were developed for a period of 10 years from 2018 to 2028 using the local conditions of groundwater utilization as well as projected rainfall. The rise in water level in rural areas is observed resulting from artificial sources like canal recharge and irrigation return flows from irrigated lands. The rise in groundwater level is in the range of 0.13–0.31 m/year in Scenario I and 0.11–0.47 m/year in Scenario II. The decline in groundwater levels is noticed in urban areas which are a result of heavy domestic and industrial groundwater withdrawal and absence of recharge areas. The decline in groundwater level is in the range of 0.12–0.31 m/year in Scenario I and 0.24–0.33 m/year in Scenario II.

The lack of comprehensive studies involving the quantification of groundwater depletion and aquifer deterioration has challenged the sustainable management of groundwater resources in semi-arid regions. In this study, we formulated a new pragmatic relationship consisting of a set of equations to quantify contaminated groundwater volume and groundwater virtually lost through contamination. We also used extensive monitoring of the hydraulic head and its spatio-temporal variations as well as groundwater modeling to quantify total aquifer volume, aquifer storage, and aquifer depletion. The watershed is divided into three distinct zones based on groundwater level fluctuations and recharge (Intermediate Borewell Zone-IBW, Random Borewell Zone- RBW, and Slow Borewell Zone-SBW zones). This study provides an advanced understanding of the relationship between aquifer depletion, geogenic contamination and the resultant virtual groundwater loss. Our long-term study reveals a negative change in storage/groundwater loss in poor monsoon years and a reduction in total groundwater volume which can result in aquifer depletion over time and low groundwater reserves. The decadal estimations of groundwater gain/loss for a period of ten years (2001–2010) in the IBW zone of the aquifer show a groundwater gain of 3.03 mcm (million cubic metes) but at the same time, this zone has virtually lost 1.06 mcm to contamination. Similarly, 1.3 mcm gain is estimated in the RBW zone and 0.53 mcm loss of groundwater is estimated in the SBW. The virtual groundwater losses through contamination in RBW and SBW zones are 4.5 mcm and 16 mcm. In such a situation an aquifer depletion stage beyond an economic level will be reached in most of the watershed in a few years. The contamination in these years is also high which may result in virtual loss through contamination. Under such conditions, the groundwater resource may be conditionally renewable as a part of the groundwater volume remains contaminated and unusable. These results highlight the need to understand the interconnection between groundwater contamination and continued over-exploitation which gradually moves towards aquifer depletion and conditionally renewable groundwater resources.

Wastewater generated on a global scale has become a significant source of water resources which necessitates appropriate management strategies. However, the complexities associated with wastewater are lack of economically viable treatment systems, especially in low- and middle-income countries. While many types of treatment systems are needed to serve the various local issues, we propose natural treatment systems (NTS) such as natural wetlands that are eco-friendly, cost-effective, and can be jointly driven by public bodies and communities. In order for it to be part of wastewater management, this study explores the NTS potential for removal of pollutants, cost-effectiveness, and reuse options for the 1.20 million m3/day of wastewater generated in Hyderabad, India. The pilot study includes hydro-geophysical characterization of natural wetland to determine pollutant removal efficiency and its effective utilization for treated wastewater in the peri-urban habitat. The results show the removal of organic content (76–78%), nutrients (77–97%), and microbes (99.5–99.9%) from the wetland-treated wastewater and its suitability for agriculture applications. Furthermore, the wetland efficiency integrated with engineered interventions led to the development of NTS models with different application scenarios: (i) constructed wetlands, (ii) minimized community wetlands, and (iii) single outlet system, suitable for urban, peri-urban and rural areas, respectively.

This study has been carried out in the granitic aquifer of Maheshwaram watershed, Telengana, India. In this study, groundwater sample data of 8 years were analyzed for the fluoride content with other chemical quality parameters. The correlation and factor analysis were employed to understand the mechanisms for fluoride (F) enrichment as well as the hydrochemistry of the area. These analyses addressed that the observed groundwater quality was due to water-rock interaction in the aquifer and fluoride is coming from the dissolution of fluorite and other silicate minerals like biotite and hornblende by the groundwater. Land use/land cover (LULC) study from 2002 to 2008 revealed there were significant positive changes in build-up land and negative changes in vegetation cover after 2003. The main agriculture (paddy) has been reduced to 0.97 km2 in 2008 from 2.39 km2 in 2003. The studied watershed has been characterized on the basis of F concentration into safe, transition, and unsafe groups following the WHO and BIS guidelines. The temporal variation of the three groups showed that 57.6% area of the watershed was in unsafe zone in 2000–2003, but 69.2% of the area became safe in 2006–2009. It has been found that F concentration reduced in 12.59% of the area (became safe from unsafe) accompanied by the reduction of paddy field area. After validation with present (2016) fluoride concentrations, it was found that 16.28% are vulnerable in near future. The results of this study showed that (a) the safe and unsafe zones of fluoride concentrations vary with time with the changes in other parameters associated with it like crop pattern and (b) vulnerable zone can be identified based on the susceptibility to change of safe and unsafe zones. Such studies are useful for planning and management purposes.

When flowing through Hyderabad, the capital of Telangana, India, the Musi River picks up (partially) treated and untreated sewage from the city. Downstream of the city, farmers use this water for the irrigation of rice and vegetables. Treatment of the river water before it is used for irrigation would address the resulting risks for health and the environment. To keep the costs and operational efforts low for the farmers, the use of constructed wetlands is viewed as a suitable option. Towards this end, the paper investigates the interests and perceptions of government stakeholders and famers on the treatment of wastewater for irrigation and further explores the consumer willingness to pay a higher price for cleaner produced vegetables. Full cost recovery from farmers and consumers cannot be expected, if mass scale treatment of irrigation water is implemented. Instead, both consumers and farmers would expect that the government supports treatment of irrigation water. Most stakeholders associated with the government weigh health and environment so high, that these criteria outweigh cost concerns. They also support the banning of irrigation with polluted water. However, fining farmers for using untreated river water would penalize them for pollution caused by others. Therefore public funding of irrigation water treatment is recommended.