Faculty Publications
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Item Conjunctive use in India's Varada River Basin(American Water Works Association cs-journals@wiley.com, 2009) Ramesh, H.; Mahesha, A.The use of groundwater in conjunction with surface water resources has gained prominence in regions experiencing scarce or uneven distribution of water. In the Varada River Basin in Karnataka, India, for example, an optimization model was developed for the conjunctive use of surface water and groundwater resources because of the increasing demand on agricultural and domestic sectors of this area's water supply. Monsoon rains, which occur only six months a year, predominantly control the basin's agricultural activities. However, the area has an immense need for efficient use of available water resources during the rest of the year. The model, based on linear programming, optimizes the allocation of groundwater and surface water subject to hydraulic and stream flow constraints. The model incorporates policy scenarios that add to the sustainability of the system. The developed conjunctive-use model is simple but effective in computing the optimal use of the Varada basin's water resources.Item Identification of Artificial recharge sites in hard rock terrain using RS and GIS in Chintapally Mandal, Nalgonda District, Andhra Pradesh, India(2010) Raju, A.; Reddy, A.G.S.; Venkat Reddy, D.A study has been undertaken to identify the favorable areas for artificial recharge in Chintapally mandal in Nalgonda district, Andhra Pradesh. Geographical Information System (GIS) and Remote Sensing technology contributes an efficient and effective result oriented methods for studying the occurrence and movement of groundwater resources. Integration of various thematic layers such as geomorphology, slope, soil types, lineament density, and drainage density have been used to identify the suitable zones for the artificial recharge in the study area. For identifying the suitable zones, weightage and ranking scores were assigned to each thematic layer then using ARC/INFO GIS software, the above themes have been integrated and the areas suitable for artificial recharge have been identified using spatial analysis tools from GIS environment. The favorable areas for artificial recharge have been categorized into Very Good, Good, Moderate to Good, Moderate, Poor to Moderate and poor for recharge in the study area. © 2010 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Tropical, Seasonal River Basin Development through a Series of Vented Dams(2011) Shetkar, R.V.; Mahesha, A.Tropical rivers are predominantly seasonal in nature, and managing water resources during the deficit period is becoming more difficult because of the rapidly increasing demand for water. The present investigation focuses on harvesting Netravathi River water in the southern Indian peninsula through a series of vented dams with an estimated storage capacity of 102 Mm3 for use during the deficit period. A brief hydraulic design of a vented dam at a specific location is presented. The spacing and capacity of these reservoirs were worked out on the basis of the dam height and the river characteristics. The proposed vented dams are seasonal dams, and the closure of the vents will be decided on the flow available (i.e., 95% dependable flow), the storage capacity, and the minimum water release required for the downstream ecosystem. The appropriate time to start storing water in the vented dams was estimated to be in the month of November, and the entire process of storing water in the vented dams may last for about 41 days. An operational protocol for the storing process is presented. The investigations of aquifer parameters were performed by using electrical resistivity, pumping, and soil tests. The results indicated that the aquifer is shallow, unconfined in nature, and had a depth ranging from 18 to 30 m and hydraulic conductivity ranging from 62.6 to 406 m/day. A multiple regression model developed to assess the groundwater recharge in the adjoining well fields indicated that water table fluctuations may be 30% of reservoir level fluctuations. Because the river is also tidal in nature, a saltwater exclusion dam is proposed at the lower reaches of the river to prevent the entry of saltwater along the river during the summer period. © 2011 American Society of Civil Engineers.Item Fuzzy logic modeling for groundwater level forecasting of west coast region in India(2011) Dandagala, D.; Deka, P.C.Forecasting the groundwater table in unconfined aquifer is essential for efficient planning of conjunctive use in a basin. In this study, fuzzy logic (FL) models have been developed for groundwater level forecasting in west coast humid region of Karnataka state, India. The FL modeling was carried out to forecast the groundwater table by one week lead time at three different sites over the study area. Mamdani fuzzy inference system was adopted in the present study and finally centroid of area defuzzification method has been applied to obtain crisp output. The results concluded that the FL model performed quite satisfactorily as assessed by various performance indices such as Root mean square error, Coefficient of correlation, and Mean absolute error. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item A comparative study on RBF and NARX based methods for forecasting of groundwater level(2011) Dandagala, D.; Deka, P.C.Evaluation and forecasting of groundwater levels through time series model (s) helps for the sustainable development of groundwater resources. The focus of the present study is on the application of Radial Basis Function (RBF) and Non Linear auto-regressive with exogenous variable (NARX) data driven models to forecast groundwater level for multiple input scenario's and also multiple lead time. Weekly time series groundwater level data has been used as input and the models are developed to forecast one, two, three, four, five and sixth week ahead. Root mean square error (RMSE) and correlation coefficient (Cc) are used for evaluating the accuracy of the models. Based on the comparison of results, it was found that the RBF models are superior to the NARX models in forecasting groundwater level considering RMSE and Cc. The obtained result indicates that the RBF has high performance and consistent upto fourth week lead time and decaying performance for NARX models. Hence, RBF and NARX have the potential in forecasting groundwater level efficiently for multi step lead time. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Quantifying aquifer properties and freshwater resource in coastal barriers: A hydrogeophysical approach applied at Sasihithlu (Karnataka state, India)(2012) Vouillamoz, J.-M.; Hoareau, J.; Grammare, M.; Caron, D.; Nandagiri, L.; Legchenko, A.Many human communities living in coastal areas in Africa and Asia rely on thin freshwater lenses for their domestic supply. Population growth together with change in rainfall patterns and sea level will probably impact these vulnerable groundwater resources. Spatial knowledge of the aquifer properties and creation of a groundwater model are required for achieving a sustainable management of the resource. This paper presents a ready-to-use methodology for estimating the key aquifer properties and the freshwater resource based on the joint use of two non-invasive geophysical tools together with common hydrological measurements.
We applied the proposed methodology in an unconfined aquifer of a coastal sandy barrier in South-Western India. We jointly used magnetic resonance and transient electromagnetic soundings and we monitored rainfall, groundwater level and groundwater electrical conductivity. The combined interpretation of geophysical and hydrological results allowed estimating the aquifer properties and mapping the freshwater lens. Depending on the location and season, we estimate the freshwater reserve to range between 400 and 700 L m??'2 of surface area (A± 50%). We also estimate the recharge using time lapse geophysical measurements with hydrological monitoring. After a rainy event close to 100% of the rain is reaching the water table, but the net recharge at the end of the monsoon is less than 10% of the rain. Thus, we conclude that a change in rainfall patterns will probably not impact the groundwater resource since most of the rain water recharging the aquifer is flowing towards the sea and the river. However, a change in sea level will impact both the groundwater reserve and net recharge. © Author(s) 2012.Item Terrain analysis and hydrogeochemical environment of aquifers of the southern west coast of Karnataka, India(2012) Honnanagoudar, S.S.; Venkat Reddy, D.; Mahesha, A.Dakshina kannada district is situated in peninsular region. The peninsula is composed of geologically ancient rocks of diverse original and most of them have undergone metamorphism. The early Precambrian tonalitic gneisses invaded by granites, granulites and dolerite dykes. Granulites are mostly restricted to areas south of Mangalore. High grade alumina rich (corundum bearing) metamorphic schists have been encountered and younger alkaline intrusive rocks like Aegerine syenites have been reported. There are five rivers and estuaries. Number of lineaments cut across each other and some lineaments are parallel to each other. The Arabian sea class is the largest among other land cover features in the study area. The river/tidal creek land cover appear as long irregular and sinous in outline. Mulki river, Netravati river, Gurupur river at southern terrain. The qualities of groundwater at sandy aquifer are good, lateritic/weathered gneissic rocks it is sweet. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Parameter estimation and vulnerability assessment of coastal unconfined aquifer to saltwater intrusion(2012) Mahesha, A.; Vyshali; Lathashri, U.A.; Ramesh, H.The focus of the present work is to characterize a tropical, coastal aquifer and to carry out its vulnerability to saltwater intrusion using hydrogeological parameters. The characterization of the aquifer involves pumping tests, vertical electrical sounding, and water quality analysis carried out at 41 monitoring wells. The area under investigation lies between two tropical, seasonal, tidal rivers, i.e., Pavanje and Gurpur rivers, joining the Arabian on the west coast of India. The aquifer is predominantly shallow and unconfined, having moderate to good groundwater potential with transimissivity and specific yield ranging from 49.2 to 461:4 m2/day and 0.00058 to 0.2805, respectively. The electrical resistivity tests indicated that the thickness of the aquifer ranges from 18 to 30 m. The study also investigates the saltwater affected areas in the region the vertical electrical sounding and water quality analysis. The resistivity results revealed several probable isolated saltwater intruded pockets in the region with resistivity less than 70 Om. From the salinity analysis of water, the locations that are affected during February to May (summer) and throughout the year are identified. The wells that are located close to the coast (< 350 m) and at lower elevations (well bottom < +1 m) were found to be saline throughout the year. Also, wells along the banks of the river show considerable salinity (> 200 ppm) during the summer period from tidal inflow along the rivers. The water samples were also analyzed for chloride to bicarbonate ratios during December to May at all the monitoring wells and were found to be exceeding the allowable limit at several locations. The saltwater vulnerability maps are derived for the area by the index-based method using the hydrogeological parameters. The method was found to be effective while compared to the field observations. The results from the analysis indicate that the aquifer is medium to highly vulnerable to saltwater intrusion at majority of the locations. The impact of projected sea level rise by 0.25 and 0.50 m from the climate change is also assessed on the vulnerability of the region to saltwater intrusion. © 2012 American Society of Civil Engineers.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 Semi Impervious Subsurface Barrier for Water Conservation in Lateritic Formations(Springer India sanjiv.goswami@springer.co.in, 2014) Udayakumar, G.; Mayya, S.G.The coastal districts of Karnataka in west coast of India experience acute shortage of drinking water during dry season in spite of heavy monsoon rains. Though sufficient recharge of ground water takes place, depletion of water table is very quick, once the rain recedes. It is mainly attributed to the presence of porous and highly permeable laterites and lateritic soils. The hydraulic conductivity of these soils varies in the range of 10?4 to 10?5 cm/s. The conventional water harvesting methods fail to solve the problem. It is necessary to explore innovative method to regulate the lateral subsurface flow and maintain a high water table over a prolonged period of time. The present work is an attempt to explore the possibility of using semi impervious Subsurface Barrier (SSB) to regulate and control the lateral flow of water in the unconfined aquifer in lateritic formations. Appropriate barrier material is arrived at using the locally available soil and the required properties are established. A SSB is built in a suitable location in an identified microwatershed using lateritic soil and the composite soil prepared by mixing requisite percentage of lateritic soil and clay. The hydraulic conductivity of these soils is maintained in the range of 10?6 to 10?7 cm/s so as to behave as semi impervious. The performance analysis is carried out by observing water levels in selected open observation wells before and after the construction of the barrier. The results have shown the successful performance of SSB in maintaining a high water table over a prolonged period of time during summer months, both in u/s and d/s of the barrier. © 2014, The Institution of Engineers (India).
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