Faculty Publications
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Item Evaluation of water quality index for drinking purposes for river Netravathi, Mangalore, South India(2008) Avvannavar, S.M.; Shrihari, S.An attempt has been made to develop water quality index (WQI), using six water quality parameters Dissolved oxygen (DO), Biochemical oxygen Demand (BOD), Most Probable Number (MPN), Turbidity, Total Dissolved Solids (TDS) and pH measured at eight different stations along the river basin. Rating curves were drawn based on the tolerance limits of inland waters and health point of view. Bhargava WQI method and Harmonic Mean WQI method were used to find overall WQI along the stretch of the river basin. Five point rating scale was used to classify water quality in each of the study areas. It was found that the water quality of Netravathi varied from Excellent to Marginal range by Bhargava WQI method and Excellent to Poor range by Harmonic Mean WQI method. It was observed that the impact of human activity was severe on most of the parameters. The MPN values exceeded the tolerable limits at almost all the stations. It was observed that the main cause of deterioration in water quality was due to the lack of proper sanitation, unprotected river sites and high anthropogenic activities. © Springer Science+Business Media B.V. 2007.Item Morphometric evidences for neotectonism in the Mulki River basin of coastal Karnataka, India(2011) Radhakrishnan, K.; Lokesh, K.N.Mulki River basin, a rectilinear midland river draining the coastal Dakshina Kannada districts of Karnataka located in the Mulki-Pulikat Lake axis in south Indian Peninsula shield has been analysed for various morphometric characteristics to understand the tectonic conditions of the basin along with supporting evidences of geomorphology, geology and structural features using Remote Sensing and GIS technology. The regional neotectonism suggested by earlier workers evidenced through geomorphologic features and geology of the area has been established through morphometric analysis. Even though Mulki, a 6 th order river basin obeys the Horton's laws of stream order it disobeys the Horton's law of stream length, indicating the regional uplift due to neotectonic activities. Fluctuating stream length ratio of successive stream orders in the basin again stress upliftment and a late youth stage development of geomorphic features reflected in slope and topographic conditions. The range of varying bifurcation ratios and the low Form Factor along with Circularity and Elongation Ratios strongly suggest a geologically and structurally controlled drainage system with elongated basin shape and high relief pointing towards neotectonism. A very low relief ratio of 0.008342, with entrenched meandering plain and a steep structural ridge within the basin indicates a rejuvenation of the basin with regional uplift. A very coarse graded drainage texture of 7.84 with low stream frequency of 2.5 and a drainage density of 1.877km/km 2 suggest that the area is having highly resistant permeable subsoil in a low relief terrain indicative of neogene tectonic activities. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Ground water potential assessment of Haladi River basin in Westernghat of Udupi district, Karnataka, India(2013) Mahadeve Gowda, S.K.; Nagaraj, M.K.For a sustainable development of water resources, it is imperative to make a quantitative estimation of the available water resources. It is necessary to maintain the groundwater reservoir in a state of Dynamic equilibrium over a period of time and the water level fluctuations have to be kept within a particular range over the monsoon and non-monsoon seasons. Groundwater is a dynamic system. The total annual replenishable resource is around 43 M ha-m. The development and over-exploitation of groundwater resources have raised the concern and need for judicious and scientific resource management and conservation. Among the two major water resources, surface and ground water, it is the ground water resource, which needs to be managed carefully, especially in drought prone areas. To assess the groundwater potential, a suitable and accurate technique is required for a meaningful and objective analysis. A critical study is carried out on the different methods of estimating the groundwater potential and compared to arrive the most suitable technique for practical utility. In this work, five methods of estimating groundwater recharge were studied viz., 1. Yearly water level fluctuation 2. Ten year average water level fluctuation 3. Fluctuation between the lowest and highest water levels over ten years 4. Relationship between rainfall and recharge Method. The results of this study helps in accurate prediction of groundwater availability, which in turn may avoid groundwater over exploitation and help to restore the eco-systems. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.Item Streamflow response to land use-land cover change over the Nethravathi River Basin, India(American Society of Civil Engineers (ASCE), 2015) Babar, S.; Ramesh, H.Land use-land cover change (LULC) has considerable impacts on hydrologic response at the watershed level. Quantitative assessment of LULC impacts on runoff generations is vital for water resources development. The soil and water assessment tool (SWAT) model was used to study the effect of LULC change on streamflows. In addition to this, the present study proposed a newly developed flow-routing model called runoff coefficient routing model (RCRM). This new model is simple and requires limited data, such as precipitation, LULC and streamflows as compared to other models, which require meteorological and many more input data. The Nethravathi River basin was selected for testing the RCRM model with the SWAT model to study land use-land cover change on streamflows. The SWAT model and RCRM model have been calibrated for 2001-2005 and validated for 2006-2009 daily data. Results have shown that the simulated streams are well correlated with observed streamflows with a coefficient of correlation (R2) equal to 0.82 in calibration and 0.68 in validation period. Whereas, the RCRM model results have shown R2 of 0.81 and 0.66 in the calibration and validation period. Finally, the SWAT and RCRM results were compared. It is observed that the results of the RCRM model have shown a good agreement with SWAT model results of R2 equal to 0.99 and 0.98, respectively, in the calibration and validation period. The sensitivity analysis was also carried out based on Latin hypercube one factor-at-a-time (LH-OAT) method using the SWAT model and found 11 sensitive parameters out of 28 parameters. Model performance was carried out using the Nash-Sutcliffe model efficiency coefficient (NSE) and found 0.81 for calibration and 0.62 for the validation period in the SWAT model. RCRM has NSE of 0.79 and 0.63. The response of the streamflows for the year 2013 was simulated from the calibrated model. The results showed that the observed streamflows have shown good correlation with simulated streamflows with R2 values of 0.86 and NSE of 0.81. From the results, it is concluded that the runoff shows early response in the year 2013 compared to the year 2003. This is mainly due to changes in LULC, which shows the conversion of forest to agricultural area and increase in built-up area from 2003 to 2013. The effect of LULC change on the hydrological model parameters were calculated and observed a decrease in evapotranspiration (ET) of about 4.5%, an increase in runoff of about 0.9%, and an increase in groundwater of about 1.12%. In conclusion, the proposed RCRM in the present study simulates streamflows at par with the SWAT model with only few input data. Hence, the newly developed RCRM model would be used to study streamflows responses to LULC changes. © 2015 American Society of Civil Engineers.Item Modelling stream flow and soil erosion response considering varied land practices in a cascading river basin(Academic Press, 2020) Venkatesh, K.; Ramesh, H.; Das, P.[No abstract available]Item Effect of roughness coefficient on discharge and flow depth by using hydraulic model for nethravathi river Basin, India(Inderscience Publishers, 2021) Kappadi, P.; Nagaraj, M.K.; Deka, P.C.The river stage and discharge are dynamic due to various factors affecting the flow characteristics in a natural channel. The channel roughness plays an important role since it is not a constant parameter and varies along the length of the river. The objective of the present study is to assess the variation of Manning's roughness coefficient on flow characteristics of Nethravathi River. In the study, 1D Saint-Venant equation-based HEC-RAS hydraulic model was used to simulate the effect of roughness coefficient (Manning's coefficient n) on discharge and stage of river flow. The model result showed good consensus between model computed flow discharge values and observed flow discharge measured at downstream gauging station. The study found that the computed stage values increased whereas the associated peak discharge decreased with the increase in Manning's roughness coefficient. The stage-discharge rating curves revealed that Manning's n value is relatively more sensitive at higher discharge values. © 2021 Inderscience Enterprises Ltd.Item Effect of disturbed river sediment supply on shoreline configuration: A case study(Taylor and Francis Ltd., 2022) Yadav, A.; Dodamani, B.M.; Dwarakish, G.S.The magnitude of river sediment supply and its distribution play a significant role in coastal sediment dynamics, especially in erosion and deposition. Due to the construction of the dam, obstruction in the natural flow of water occurs, and part of the sediment is trapped. In the present study, the Kali river catchment and its river-mouth at Karwar, Devbagh, and Ravindranath Tagore beaches are considered as the study area, to assess the impact of dams on coastal processes. Landsat data for 42 years, from 1975 to 2017, were collected and analyzed using DSAS, an ArcGIS extension. The sediment yield estimated at the Kali river basin outlet, without the dam is 4.19 t/ha/yr and with the dam, it is estimated to be 1.42 t/ha/yr. Similarly, for the Aghanashini river basin outlet, the sediment yield was found to be 4.58 t/hr/yr. From the results of shoreline analysis, it is found that after the construction of the dam, Devbagh beach is under erosion at the rate of ?0.93 m/yr End Point Rate (EPR) and ?0.47 m/yr Linear Regression Rate (LRR). Ravindranath Tagore beach also has undergone erosion, which is ?0.75 m/yr (EPR) and ?0.97 m/yr (LRR). Further, both the beaches have been changed to the erosion zone. © 2021 Indian Society for Hydraulics.Item Flood susceptibility modeling based on morphometric parameters in Upper Awash River basin, Ethiopia using geospatial techniques(Springer Science and Business Media Deutschland GmbH, 2022) Tola, S.Y.; Shetty, A.The hydrological response, such as direct surface runoff, is linked to the characteristics of the watershed. Evaluation and knowledge of geomorphometric parameters in relation to floods and the identification of specific flood-prone sites in the basin are critical for mitigation measures. Despite advancements in geospatial tools, the utilization of geospatial data in many river basins prone to flooding and erosion is minimal. Morphometric aspects: linear, areal, and relief analysis of the Upper Awash River basin were performed in four subbasins to better understand the hydrological signatures behaviour. The topographic wetness index (TWI) and topographic position index (TPI) were also used to determine the extent of inundation. The aggregated parameters revealed that SB-1 is highly susceptible to flooding, SB-3 and SB-4 are moderately susceptible, and SB-2 is low. However, based on the geomorphologic instantaneous unit hydrograph, SB-2 and SB-4 demonstrated rapid response and a high flood generating potential. The degree of susceptibility was determined by incorporating the TWI and TPI through overlay analysis. Overall, the Upper Awash River basin accounts for 23%, 42%, and 36% of the total bay has been classified as high, medium, and low flood-prone, respectively. According to the study, topographic indices (TWI and TPI) are critical attributes that show specific flood potential areas and inundation extents in addition to morphometric parameter-based flood susceptibility analysis. The analysis provided input for holistic water and soil erosion management by providing the hydrological behaviour of the stream, geomorphological characteristics, basin responsiveness, and stream power to flood potential and denudation characteristics in the subbasins. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Quantification of change in land cover and rainfall variability impact on flood hydrology using a hydrological model in the Ethiopian river basin(Springer Science and Business Media Deutschland GmbH, 2023) Tola, S.Y.; Shetty, A.Changes in land cover and climate are the dominant factors that significantly impact the hydrological process. However, the impact on flood response behaviour varies spatiotemporally. This study quantitatively assessed the effects of individual and coupled changes in land cover and climate on peak and high flows in the upstream and downstream parts of the Upper Awash River basin. Two time periods were chosen for comparison: baseline (1988–2001) and evaluation (2002–2015). The Soil Water and Assessment Tool (SWAT) was used to estimate the impact of these changes. The model satisfactorily simulated daily and extreme flows. The evaluation of annual maximal discharge variability between 1985 and 2015 at upstream and downstream stations showed significant positive and insignificant negative trends, respectively. However, the sub-basin’s annual wet day rainfall (PRCPTOT) showed a downward trend. The annual maximal discharge–PRCPTOT relationship was significant during the baseline but later had no significance. The SWAT model showed that the main factor that affected the changes in upstream flow was the land cover change, increasing peak and high flow by 38.69% and 11.95%, respectively, compared to the baseline period. However, combined changes resulted in downstream peak and high flow reductions of 19.55% and 50.33%, respectively. As a result, changes in flood characteristics are strong functions of land cover, especially in the upstream sub-basin and land cover and climate in the downstream sub-basin. Overall, the impact of changes in the cropland-dominated basin was noticeably different. The study assists water resource managers in understanding the causes of hydrological dynamics and developing mitigation strategies. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Recent Changes in Hydrometeorological Extremes in the Bilate River Basin of Rift Valley, Ethiopia(American Society of Civil Engineers (ASCE), 2023) Lambe, B.T.; Kundapura, S.The hydroclimatic extremes such as floods and droughts have been causing damage and losses with rising frequency than ever before. The human-induced and internal climate variability create extreme events and local hydrometeorological changes influencing climate-sensitive sectors. This research is aimed at analyzing the recent changes in the hydrometeorological extremes using indices over the Bilate basin in Ethiopia. Mann-Kendall and Sen's slope estimator were used to examine changes in hydrometeorological extreme indices. The rainy days' rate of change falls between þ10.64 mm in the downstream to −10.67 mm in the upstream north. The wet day rainfall and heavy rainfall day indices were stronger in the basin's southwest, implying more likely flood events. The consecutive dry days show a rising tendency with more variability, while the consecutive wet days show no trend with less variability. The change point analysis revealed inconsistencies for the majority of the extreme indices. The stations' average warmest nights and days significantly increased at a rate of 0.0358°C and 0.0320°C per annum, respectively. The coldest nights in most of the stations show a significant and negligible rise in the basin while on the coldest days more than half of the stations declining. The peak flow in the annual and seasonal time series shows a rising trend and a dominant rise in most low flow indices, which possibly flashes downstream flooding. The global and local climate anomalies revealed a weak correlation, but with overlap of wet and drought years. Basin water resource plans may benefit from identified overlap cross of threshold years for improved flood control and drought monitoring. © 2018 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.