Impact of climate change on hydrology of Manjalar sub basin of river Vaigai in Tamil Nadu, India

This study evaluates the impacts of possible future climate change scenarios on the hydrology of the catchment area of the Manjalar sub basin of River Vaigai, Tamil Nadu, India carried out at the department of Soil and Water Conservation Engineering, Tamil Nadu Agricultural University during the period of 2011-2014 using Soiland Water Assessment Tool (SWAT). For the climate impact assessment the hydrological model was driven with output of bias corrected Earth System Models of the Coupled Model Intercomparison Project Phase 5 (CMIP5): HadGEM2. Climate scenarios were downscaled to a grid resolution of 0.22° x 0.22°. In this study RCP 4.5 and RCP 8.5 were included for future assessment with three future periods: 2012–2039, 2040–2069, and 2070–2098. The projected increase in maximum and minimum temperature for RCP 4.5 scenario is 0.8 to 2.3 ºC and 0.7 to 1.6 ºC and for RCP 8.5 scenario is 1.1 to 4.0 ºC and 1.0 to 3.1 ºC, respectively. Rainfall is projected to an increase between 9.2 to 15.2 per cent for RCP 4.5 scenario and an increase of 13.6 to 18.8 per cent for RCP 8.5 scenario during 21st century. The soil water storage and stream flow contribution to ground water are likely to increase in RCP 4.5 scenario and it would again decline for RCP 8.5 scenario during 21st century. The increase in annual rainfall evapotranspiration and surface runoff would be more in RCP 8.5 scenario compared to RCP 4.5 scenario. The possible changes projected by the study provide a useful input to effective planning of water resources of the study area

Spatial and temporal analysis of drought in Manjalar sub-basin of Vaigai in Tamil Nadu using standardized precipitation index

Drought is universally acknowledged as a phenomenon associated with scarcity of water. Drought characterization is essential for drought management operations. Using drought indices is a pragmatic way to assimilate large amounts of data into quantitative information that can be used in applications such as drought forecasting, declaring drought levels, contingency planning and impact assessment. Using monthly mean precipitation data for a period of 1982-2012 from 12 raingauge stations in the Manjalar sub-basin of Vaigai using Standardized Precipitation Index (SPI) is produced for the drought analysis with the time scale of 3 months (SPI-3), 6 months (SPI-6) and 12 months (SPI-12) as they are applicable for agriculture and hydrological aspects, respectively. It was observed that the basin experienced frequent droughts for all months of the year. The highest percentage of occurrence of drought was observed in the month of July (15.3), May (15.4) and August (15.6) at SPI-3, SPI-6 and SPI-12 respectively. On an average we observed 32.6, 8.6, 5.6 and 2.3 percentages of drought occurred by mild, moderate, severe and extreme drought respectively with respect to SPI-12. The results showed that mild droughts occur most frequently and extreme droughts occur least frequently and the basin suffered severe drought during the year of 1985, 2004 and 2006. The central and south eastern parts of the basin had more potential sensitivity to the droughts in comparison with the other areas of the basin

Drip irrigation on productivity, water use efficiency and profitability of turmeric (Curcuma longa) grown under mulched and non-mulched conditions

Turmeric cultivation primarily thrives in India, with significant presence in Bangladesh, Thailand, Cambodia, China, Indonesia, Philippines, and Malaysia. India leads globally in both area (0.19 Mha) and production (0.844 MT) of turmeric. Despite this, there's a recognized gap in research regarding the combined effects of mulching and drip fertigation on turmeric growth in Tamil Nadu conditions. Therefore, this study aims to assess how mulching and drip fertigation impact water usage, turmeric growth, productivity, and post-harvest soil health via field experiments. The treatments comprise of different mulching techniques (M1-25 μm Plastic Mulching, M2-50 μm Plastic Mulching, M3- Organic Mulching, M4-No Mulching) as the main plot, coupled with various irrigation regimes as the sub plot (S1-100% of pan evaporation, S2- 80% of pan evaporation, S3- 60% of pan evaporation), in a split plot design. Findings show that 50-μm Plastic Mulching (M2) notably enhances turmeric growth parameters, including plant height, biomass, leaf count, and yield attributes such as tillers and rhizomes, compared to no mulch. Significantly, when 80% of pan evaporation is utilized in drip irrigation, it showcases the most pronounced plant growth and yield characteristics, with plastic mulch at this level significantly improving water and nutrient use efficiency while increasing beneficial compounds like Curcumin and oleoresin. The highest fresh rhizome yield is observed with 50-μm plastic mulch and 80% pan evaporation (M2S2), displaying a 39.79% increase compared to the control. Additionally, the study notes effects on microbial populations and mulch degradation. Economically, M2S2 exhibits the highest profitability with a benefit-cost ratio of 3.23 compared to other treatments. Implementing these practices not only enhances yields but also conserves water (estimated at 9.15 mm3) while emphasizing the importance of drip irrigation, fertilizer application, and mulching in boosting turmeric productivity, optimizing resource efficiency, and ensuring economic and environmental sustainability

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Not AvailableAn experiment under rainfed condition was conducted in the farmer's field in the Nilgiris, the North-Western part of Tamil Nadu for evaluating the influence of conservation practices on soil moisture and plant growth under new tea plantation. One year old B-6 tea clones were planted at double hedge spacing (135 x 75 x 75 cm) in two slopes (8-12 and 30-35%) with treatments viz., contour staggered trenches (CST) in the walking rows (space between pairs of tea rows), vegetative barrier (VB) of geranium in walking rows, CST and VB of geranium in alternate walking rows, CST with cover crop of beans as well as in control condition. Minimum runoff in CST with cover crop followed by CST and CST with VB in both the slopes proved the cause of CST either alone or in combination in reducing runoff. Runoff retention in the trenches attributed to higher soil moisture in CST (25.6%) and CST with cover crop (24.8% ) followed by CST with VB (22.8%) in 8-12% slope with similar trend as well in 30-35% slope during non-monsoon period. Tea canopy followed a similar trend to that of soil moisture content with maximum (39.5%) in the CST with cover crop followed by CST (38.4%) and minimum in control just before the first harvest in 8-12% slope. The maximum plant height obtained in CST with cover crop followed by CST may be due to similar reason as in canopy development. Higher yield from all the conservation practices over control (3.8 t ha -1) with maximum in -CST with cover crop (4.7 t ha-1 ) followed by CST (4.4 t ha-1 ) in 8-12% slope was due to better growth resulting from higher soil moisture.Not Availabl