Hydrogeological and Hydrochemical Characterization of Coastal Aquifers with Special Reference to Submarine Groundwater Discharge in Uttara Kannada, Karnataka, India

In coastal areas of our country, in spite of having excess rainfall (more than 3000 mm), groundwater become a rare commodity during summer. Number of researchers have discussed the issues related to water scarcity of coastal areas where there is a huge pressure on environment due to increased population, tourism, agriculture and industrial growth. Fast depletion of groundwater is also reported in coastal districts due to continuous discharge of direct runoff and also through subterranean flow which is termed as Submarine Groundwater Discharges (SGD). Large quantity of contaminants enter the ocean system through runoff. This necessitated a detailed investigation to understand the hydrological processes involved and the source of contaminants. The present investigation is an attempt to make quantitative and qualitative assessment of SGD based on hydrological, hydrogeological and hydrochemical components. Accordingly, water balance components were evaluated based on hydrological and hydrogeological investigations. Hydrochemical parameters were also evaluated to understand the impact of seawater intrusion in pre and postmonsoon of 2019. Study revealed that, there are signatures of considerable quantity of submarine groundwater discharge in parts of Honnavara, Kumta, Ankola and Karwar talukas. The influence of seawater in coastal aquifers is quite rare all along the coast of Uttara kannada district which is attributed to high groundwater recharge (15-20%) occurring in catchment areas

Texture and mineralogy of Periyar river (southwest coast of India) sediments

78-80Bed sediments from the Periyar river were collected and analysed to understand the sedimentological characteristics. Grain size of the Periyar sediment varies from the size of a granule to that of a medium clay. Majority of the sediments are poorly sorted, positively skewed and platy to mesokurtic in nature. Heavy minerals are concentrated in medium fraction (125 mum). Major heavy minerals observed are opaques followed by hornblende, hypersthene, mica and sillimanite. However, the sediments in the downstream shows an additional input when compared to the upstream sediments. A wide variation in the upstream and downstream sediments are attributed to the multiple source of derivation and varying energy conditions during the deposition

Provenance, Sedimentation and Geochemistry' of the Modern Sediments of time Mud Banks Off the Centrai Keraia Coast, India

This thesis is an attempt to Provenence, Sedimentetion and Geochemistry of the Modern Sediments of the Mud Banks off the Central Kerela Coast, India. In the present doctoral work, an attempt has been made to study in detail the mud banks of central Kerala, i.e. of Narakkal, Saudi and Purakkad areas which are reported as permanent mud banks, since olden days. The studies have been conducted during the years 1985 and 1986. The important findings of the study is stated as clay mineralogical studies of the rivers, lake and mud bank sediments reveal that the dominant clay mineral is kaolinite followed by montmorillonite, illite and gibbsite. Geochemical analysis of the Vembanad lake and mud bank sediments show that the iron and manganese are widely distributed both in the lake and mud bank sedimentsCochin University of Science and TechnologyMarine geology division, School of marine science, Cochin University of Science and Technolog

Estimation of Root zone salinity using SALTMOD -a case study *Corresponding Author

This study aims to estimate the Root zone salinity of salt affected areas of some parts of Gokak and Ramdurg taluks of Belgaum districts and Mudhol taluk of Bagalkot districts, Karnataka, India. The study area falls under semiarid and drought hit areas. The hydro-salinity model "SALTMOD" was applied for this study area, which computes the salt and water balance for the root zone, transition zone and aquifer zone. The model was applied to the selected agriculture plots at Gokak, Mudhol and Ramdurga taluks for the prediction of root-zone salinity and leaching efficiency. The model simulated the soil-profile salinity for 20 years under different conditions, viz. with subsurface drainage and without subsurface drainage. The salinity level shows a decline with an increase of leaching efficiency. The leaching efficiency of 0.2 shows the best match with the actual efficiency under adequate drainage conditions. However, without drainage there is a drastic increase in salinity over the years there by indicating the necessity of artificial drainage system .The model shows a steady increase, though at a slow pace over the years, reaching the levels up to 5.8 ds/m to 9.8 ds/m at the end of the 20 years period. If suitable drainage system is not provided, the study area will further get salinized thus making the land uncultivable. From the present study it is evident that it is necessary to provide proper drainage facilities to control the salinity levels in the study area

The impact of forest use and reforestation on soil hydraulic conductivity in the Western Ghats of India:implications for surface and sub-surface hydrology

There is comparatively limited information in the humid tropics on the surface and sub-surface permeability of: (i) forests which have been impacted by multi-decades of human occupancy and (ii) forestation of land in various states of degradation. Even less is known about the dominant stormflow pathways for these respective scenarios. We sampled field saturated hydraulic conductivity, K* at 23 sites at four depths (0 m, n = 166), (0.10 m, n = 139), 0.45–0.60 m, n = 117, (1.35–1.50 m, n = 117) under less disturbed forest (Forest), disturbed production forest of various local species (Degraded Forest) and tree-plantations (Acacia auriculiformes, 7–10 years old, Tectona grandis, >25–30 years old, Casuarina equisetifolia, 12 years old) in the Uttar Kannada district, Karnataka, India, in the Western Ghats. The sampling strategy was also undertaken across three physiographic blocks and under three main soil types. Subsequently the determined K* were then linked with rainfall intensity–duration–frequency (IDF) characteristics to infer the dominant stormflow pathways. The Degraded Forest shows an order of magnitude decline in K* at the surface as result of human impacts at decadal to century time scales. The lowest surface permeability is associated with the Degraded Forests over the Laterite (Eutric Nitosols and Acrisols) and Red soils (Eutric Nitosols) and infiltration-excess overland flow, IOF probably occurs. Further there is a progressive decline in K* with depth in these soils supporting Degraded Forests. The A. auriculiformes plantations over the Red and Lateritic soils are progressively restoring the near-surface K*, but their K* still remain quite low when compared to the less disturbed forest permeability. Consequently these plantations still retain the ‘memory’ from the previous degraded state. In contrast the permeability of the Black soils (Vertisols) are relatively insensitive to T. grandis plantations and this soil group has a very low K*, irrespective of land cover, so that IOF likely prevails. Overall, the Laterites are the most variable in K* when compared to the other soil groups. Thus when compared to other studies, IOF is probably more prevalent in this region. More especially so, when taking into account the marked reduction in surface K* during the wet season when compared to dry season measurements. In addition, we have demonstrated the potential for the ‘infiltration – trade-off’ hypothesis to be realized in this landscape under certain conditions of land degradation and restoration. It is most relevant to the combination of degraded sites and A. auriculiformes plantations on Red or Laterite soils using the less disturbed forests as the baseline. The intensity of forest use and effects of monoculture plantations on soil ecology (relative to native, mixed forests) is likely to be the critical factor in affecting surface K* over time. Predicted changes in the intensity of rain events in the future is likely to enhance overland flow on degraded sites on all soils and especially on Black soils, and restoration efforts by all stake-holders, preferably using native or non-invasive species, are needed to address this concern