Faculty Publications

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Future transition in climate extremes over Western Ghats of India based on CMIP6 models
(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, S.; Umesh, P.; Shetty, A.
The effect of climate change on the tropical river catchments in the Western Ghats of India is studied using the Coupled Model Intercomparison Project-6 data (CMIP-6). Multi-model ensembles of rainfall and temperature are constructed using the Random Forest ensemble technique for bias-corrected GCMs in the near future (2014–2050) and far future (2051–2100) horizons. For the two catchments each in the southern, central, and northern Ghats, the trend in minimum and maximum temperatures, precipitation, and other indices are calculated. By 2100, dry sub-humid and humid catchments will see a higher increase in mean annual temperature than per-humid central catchments. In future decades, the warm days and nights increase by 45–50% and 40–70%, respectively, with twofold warming in the winter season. Under a climate change scenario, annual rainfall increases in Vamanapuram, Ulhas, and Purna, while Chaliyar, Netravati, and Aghanashini catchments experience a decrease in rainfall in the far future with an increase in pre-monsoon rainfall. The southern catchments are anticipated to have contrasting variations in the rainfall extremes; northern catchments face a substantial increase in very wet to extremely wet days and medium to heavy rainfall. In all catchments (excluding Vamanapuram), cumulative wet days increase with a decrease in cumulative dry days. After the mid-twenty-first century, humid to per-humid catchments encompass an increase in cool nights, whereas it disappears in dry sub-humid catchments of the Ghat. Interestingly, warming tendencies begin to slow down after 2050. This investigation can assist in comprehending the regional climate extremes in the Western Ghats to formulate better climate risk planning and adaptation strategies. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Integrated spatial and temporal variability of the system water use efficiency in a lower Baro River watershed, Ethiopia
(IWA Publishing, 2023) Befikadu, F.; Shetty, A.; Fufa, F.
The Baro Akobo River is representative of lower Baro watersheds with lost soils. Under eight landscapes, the geospatial and temporal variability of system water use efficiency (sWUE) were examined in a total area of 20,325 km2. This study used GIS, RS, Cropwat8.0, and EasyFit software. The anticipated irrigation requirement for the selected crop’s driest five months of May, February, March, January, and April was 1, 0.9, 0.78, 0.78, and 0.34 l/s/h, respectively. The sub-catchment had maximum critical test values of σ = 12.6, μ = 11.9, and γ = 0, while Sor Metu showed the smallest value of 0.80, 1.75, and 0.03. Across the watershed, the sWUE varies with runoff, with a coefficient of variation of 71%. The overall accuracy of the land cover change was 81%, the Landsat 8 images of the soil-adjusted vegetation index showed a maximum value of 0.87 and a minimum of 1.5. The normalized vegetation index ranged from a maximum of 0.58 to a minimum of 1. By 2050, the sWUE will be 10% lower temporally, but its spatial variability will be 25% higher. Therefore, soil infiltration and water storage improve, which decreases runoff and the water lost by ET and raises sWUE. © 2023 The Authors.
Climate indices and drought characteristics in the river catchments of Western Ghats of India
(Springer Science and Business Media Deutschland GmbH, 2024) Shetty, S.; Umesh, P.; Shetty, A.
The study addresses the long-term trend in rainfall, minimum and maximum temperature, and the climate indices for the river catchments located in the diverse climate of the Western Ghats of India. The dry sub-humid Chaliyar catchment and humid Kajvi catchment have shown a dramatic change in the decadal rainfall, with the decade 1950–1960 being the point of change. The monsoon rainfall has decreased in the Chaliyar and Netravati catchments and increased insignificantly in the Kajvi catchment. With the increase in mean temperature, the number of rainy days is decreasing, and intense rainfall is increasing in the pre-monsoon. The increase in minimum temperature is more severe in all three catchments, irrespective of the region’s climate. The decline in rainy days is more figurative in the humid and per-humid catchments and has seen a 16–20% decrease in R×1 day, R×3 day, and R×5 day in the past six decades with an insignificant increase in the dry sub-humid catchment. The frightful increase in warm days/nights with a decrease in cool days/nights has been alarming for the extremity of temperature in future years. The significant changes in the forest area in Chaliyar and Kajvi catchment and the increase in a built-up area in Netravati may have a decisive role in the nonseasonal variability in rainfall and temperature along with increasing greenhouse gases. In the case of meteorological drought studied using the Standardized Precipitation Index (SPI), moderate droughts have occurred over the Chaliyar and Kajvi, and extreme droughts over the Netravati catchments with no reduction in the frequency or severity of short-duration extreme rainfall events. The geographical location of the catchment has a greater impact on the characteristics of the rainfall and meteorological drought, and these changes in the hydrological regimes of the catchment have a significant bearing on the water availability in the catchments in the future years. © The Author(s) under exclusive licence to Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences 2023.

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