Showing papers by "K. P. Sudheer published in 2020"

A review of the assessment of sustainable water use at continental-to-global scale

Abstract: Freshwater scarcity and unsustainable water use are just some of the growing concerns in many parts of the world. Increasing water demand accompanied by a changing climate can lead to unsustainable use of freshwater resulting in water scarcity. Several studies have quantified sustainable water use and water scarcity at a continental-to-global scale in the past. This review focuses on the large-scale water resources assessments and the methods by which sustainable water use and water scarcity are quantified. The review is structured based on a framework that comprises the main components of water demand and supply and other aspects of sustainable water use including virtual water trade and future projections of sustainable water use. The major components of water demand and supply in such assessments are increasingly derived from global earth system models and national-level census datasets. These assessments conclude that the selection of appropriate spatial and temporal scales is critical. The grid-based global earth system models enable better spatial resampling of water information across country/political boundaries. Similarly, by refining the temporal scale from annual (the most commonly used temporal scale of assessment) to monthly time steps, water scarcity is better captured due to the distinctive seasonality of water availability and demand. This paper also discusses the role of major drivers of water scarcity. Although both changing climate and increasing water demand contribute to water scarcity, the majority of the literature concludes that the demand-driven freshwater scarcity has a much greater impact than that induced by climate change.

Investigating Atrazine Concentrations in the Zwischenscholle Aquifer Using MODFLOW with the HYDRUS-1D Package and MT3DMS

Abstract: Simulation models that describe the flow and transport processes of pesticides in soil and groundwater are important tools to analyze how surface pesticide applications influence groundwater quality. The aim of this study is to investigate whether the slow decline and the stable spatial pattern of atrazine concentrations after its ban, which were observed in a long-term monitoring study of pesticide concentrations in the Zwischenscholle aquifer (Germany), could be explained by such model simulations. Model simulations were carried out using MODFLOW model coupled with the HYDRUS-1D package and MT3DMS. The results indicate that the spatial variability in the atrazine application rate and the volume of water entering and leaving the aquifer through lateral boundaries produced variations in the spatial distribution of atrazine in the aquifer. The simulated and observed water table levels and the average annual atrazine concentrations were found to be comparable. The long-term analysis of the simulated impact of atrazine applications in the study area shows that atrazine persisted in groundwater even 20 years after its ban at an average atrazine concentration of 0.035 µg/L. These results corroborate the findings of the previous monitoring studies.

Uncertainty of hydrologic simulation, and its impact on the design and the effectiveness of water conservation structures

Abstract: The uncertainties associated with the simulation models are often ignored in operational hydrology. While many methods are available for evaluation of simulation uncertainty, most of them focus on construction of prediction bands, which alone may not be sufficient to make effective decisions. This is a serious concern in watershed management planning, especially in cases where the models are uncalibrated due to unavailability of observations. This study addressed uncertainty in hydrologic modeling, and its consideration in check dam design decisions. Size of the check dams were determined using a simulation–optimization framework by considering dual objectives of maximizing water availability for agriculture and minimizing the adverse effects on downstream reaches. The optimizer suggested distinct Pareto-optimal-front for different parameter sets of the model (in turn resulting in different simulations), indicating the influence of parametric uncertainty on the design. An analysis of the optimal solutions suggested varying check dam sizes (0.5–1.5 m) for similar objective function value, which plausibly indicate an economic impact. Nonetheless, the effectiveness of the structure (in terms of simulated wet and dry period lengths) did not exhibit significant variability across the designs (average wet period length of > 100 days). The median of the streamflow ensemble provided satisfactory performance (> 100 days wet period length and only 11–25% reduction of flow to downstream) and could be a viable choice for implementation. The results suggest that parametric uncertainty that is propagated to prediction uncertainty significantly influences the final design decisions and calls for careful assessment prior to implementation.

Mild thermal processing of cashew apple juice using ohmic heating

Abstract: Cashew apple is an under exploited fruit crop due to its seasonal and highly perishable nature. Ohmic heating is adopted for processing and preservation of cashew apple juice. Ohmic heating is widely accepted for the inactivation of enzymes and microorganisms. The optimization of ohmic heating process parameters such as voltage gradient, holding time and temperature was done based on the microbial inactivation and the variation in physico-chemical qualities of cashew apple juice. The cashew apple juice was ohmic heated at different voltage gradients (10-15 V/cm) temperatures (50-60°C) and holding times (1-5 min). Maximum microbial reduction was obtained in treatment with higher voltage gradients, temperature, and time. A treatment with a voltage gradient of 12.5 V/cm, temperature of 60°C and a holding time of 5 min resulted in highest microbial reduction. A significant change in ascorbic acid content and total colour difference was observed with the increase in temperature and treatment time. A voltage gradient of 14.21 V/cm, process temperature of 55.47°C and holding time of 2.43 min was found to be the optimum conditions for ohmic heating conditions.

Quality evaluation of thermal processed tender jackfruit during storage

Abstract: Tender jackfruit (Artocarpus heterophyllus L.), known for its unique quality attributes, is popular as a vegetable with high market value in South Asian countries. However, its year round availability is limited mainly due to seasonal nature, high perishability and limited technologies for storage and ransportation. Thermal processing may be regarded as a promising one-step solution to these concerns. The present study examined the effect of thermal processing (sterilization at 121oC and pasteurization at 90oC) and preservatives (brine, potassium metabisulphite, citric acid and their combination) on quality attributes (texture, colour, ascorbic acid, titrable acidity, and microbiology) of canned tender jackfruit during two months of storage. All the samples analysed were microbiologically safe during the storage period. The outcome of two-factor completely randomized design revealed that degradation of quality attributes of samples during storage was statistically insignificant irrespective of preservative treatment and type of thermal processing. However, there was significant variation between sterilization and pasteurization, the latter being superior in quality retention and sensory perception. Based on the result of sensory analysis, the use of pasteurization based treatments with brine (overall acceptability), citric acid (colour and texture) and citric acid-potassium metabisulphite combination (flavour) may be advocated for thermal processing of tender jackfruit samples.