Browsing by Author "Kumar Raju, B.C."

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    Analysis of historical trends in hydrometeorological variables in the upper Cauvery Basin, Karnataka, India
    (Indian Academy of Sciences, 2017) Kumar Raju, B.C.; Nandagiri, L.
    The present study examines the significance and magnitude of trends in the monthly rainfall, monthly mean maximum and minimum daily temperatures and streamflow in the Upper Cauvery Basin, Karnataka for a 30-year period, i.e. 1981-2010. Using observed data from 33 rain gauges, 6 climate stations and 4 stream gauging sites, statistical parameters -coefficient of variation (CV) and percentage departure have been calculated for average monthly values separately for three decades. As expected, CV of rainfall showed large variations from December to March, while the percentage departure also varies during these months for different decades. Statistically significant trend was observed in maximum temperature for Chikmagalur and Hassan stations. CV of minimum daily temperature showed large variability from November to March for all climate stations and also a significant increasing trend for Hassan and Bengaluru stations, while for Madikeri a decreasing trend was observed with a variation of -0.16°C/year. Not much variation was found for streamflow, except in K. M. Vadi and T. Narasipur gauge sites, which showed significant decreasing trend of -0.778 m3/s/year. Long-range dependence analysis revealed a weak persistence for both rainfall and streamflow of the basin. Results provide information regarding historical climate trends in the Upper Cauvery Basin, which can form the basis for projecting likely future trends and preparing plans for climate change mitigation and adaptation.
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    Evaluating uncertainty of the soil and water assessment tool (SWAT) model in the upper cauvery basin, Karnataka, India
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2015) Kumar Raju, B.C.; Nandagiri, L.
    Quantification of uncertainties associated with hydrological models are essential for accurate assessment of water balance components and optimal planning and management of water and land resources at basin-scale. The present study was taken up to evaluate the uncertainties associated with the Soil and Water Assessment Tool (SWAT) model using for two different techniques: i) Generalized Likelihood Uncertainty Estimation (GLUE) and ii) Sequential Uncertainty Fitting (SUFI-2) techniques. The study was carried out in the Upper Cauvery River basin (36,682 km2) located in the humid to sub-humid region of Karnataka State, India. The calibration of the model was carried out using the Nash – Sutcliffe (NS) coefficient as the objective function for both GLUE and SUFI-2 techniques. The P-factor was 67% and 71% of observed streamflow data bracketed by the 95% prediction uncertainty (95PPU) for GLUE and SUFI-2 respectively during calibration period and corresponding values of 54% and 61% during validation period. Overall results indicate the applicability of SWAT model with moderate levels of uncertainty in large basins located in the humid tropics. The calibrated SWAT model can be used for assessment of water balance components and land use management scenarios in the Upper Cauvery Basin. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.