eChapters

Year : The time taken by the earth to revolve once in its orbit round the sun.

Yellow Snow : Snow which has a yellow or golden colour due to the presence of pine or cypress pollen in it.

Zenith : The point directly overhead on the celestial sphere.
 
Zenith Angle : The angle formed by the local line perpendicular to the surface on which the radiation falls, and the position of the Sun in the sky from which the incident ray falls. 

Rainfall is precipitation (falling of any type of condensed moisture to the ground) in the form of liquid drops larger than 0.5 mm in diameter falling on the earth surface. Ordinary rain drop size varies from 0.5-4.0 mm in diameter. Rainfall is measured in term of depth of rain water (millimeters) on a solid surface provided that rain water is neither allowed to percolate nor runoff or loss in any form.

Abstract

Quality of water is affected by natural and man induced contamination to groundwater system. Area chosen for study has gained its own importance due to the location of two lignite mines and a Thermal power plant in operation. Extensive large scale pumping of water is done for lignite mining. The mine drainage and drainage from thermal power plant along with agricultural return flow from lignite charged waters increases the severity of problem. In order to achieve a panacea for the above-mentioned situation, the study has incorporated and integrated in all related factors to get a meaningful interpretation for groundwater quality and quantity management in and around Neyveli area. The frequent failure of monsoon has added to the existing problem of over exploitation. To attain a panacea for water chemistry groundwater samples were collected for four different seasons. Higher EC and TDS values are observed in Southeast and Southwest part of the study area. In Southwest monsoon and Summer seasons HCO₃Cl dominates the anions, with few representations for SO₄. In Northeast monsoon and Post monsoon season Na + K – Ca + Mg is the dominant. Thermodynamic, studies reveal that groundwater of the region are stable with Kaolinite stability field in all the silicate systems. Bicarbonates derived from silicate mineral weathering are noted in the NW, Northern and in the mining region. These regions are located in the NW and NE part of the study area. Comparison of water quality to standards shows that the water can be used for drinking and for irrigation purposes except in few locations.

Abstract

In semiarid climates, a significant component of recharge to basin aquifers occurs along the mountain front. In this scenario Mountain Front Recharge study has been carried along the foothills of Courtallam ,Tamil Nadu. A total of 53 groundwater samples were collected along the foothills and measured for major cations and anions using standard procedure. Saturation index (SI) of carbonate minerals like Aragonite,Magnesite, Calcite and Dolomite,LogpCO₂ and Ionic strength obtained from WATEQ4F output. pH plays a significant role in the saturation index of the minerals. Most of the Carbonate minerals shows undersaturation  with the pH range 7.5. Positive relationship between SI and HCO₃ is noticed. A sharp increase of pCO₂ values towards the foothills region suggests that the groundwater has been recharged by, acquiring longer flow path during its infiltration into deeper level near foot hill region. The SI of these carbonate minerals was spatially distributed to identify the areas of higher SI and also it is compared with the water level fluctuation to understand the recharge process along the foothill region as well as riparian zone.

Abstract

The geochemical signature and vulnerability of groundwater of the East Coastal aquifers of  India from Pondicherry to Nagapattinam were determined. The coastal aquifers are fragile and this situation becomes more intense in aquifer systems like that of the Pondicherry to Nagapattinam region. A total of 136 water samples were collected during pre and post monsoon of 2008 and 2009 respectively. Out of which 45 samples for each pre and post monsoon from shallow groundwater and 23 samples for each pre and post monsoon from deeper groundwater.. The samples collected were analysed for major, minor cations and anions. Selected samples were also analysed for stable isotopes (d¹⁸O and dD). The analysed samples were studied for; their utility for different purpose, the nature of the geochemical classification, their variations in ion ratios, extent of sea water intrusion and the percentage of mixing, The study reveals that chief mechanism controlling shallow groundwater is the salts precipitated in the pore spaces during the Pre monsoon were leached and dissolved during the subsequent monsoon apart from sea water intrusion. Southern part of the study area  is more vulnerable than the Northern part of the study area.

Snow is precipitation of solid water, mainly in the form of branched hexagonal crystals or stars. It is “precipitation of white opaque grains of ice”. Measurement of snow cover is related to runoff estimation and also important for hilly agriculture.

4.1. Snowfall

It is the amount of fresh snow deposited over a specified period (generally 24 hours). The measurements relate to depth and water content of the snowfall.

The surface of the earth gets heated up during the day and gets cooled during the night causing diurnal changes in the top layers of the soil. Soil temperature is an important part of micro-environment, where plant roots grow and capture the water and nutrients and thus, it affects the plant growth and yield. During crop germination also soil temperatures play vital role. Since the heat regimes of these layers are governed by the soil temperature, the measurement of soil temperature becomes extremely important.

Cloud is a visible aggregate of minute water droplets and/or ice particles, or both in the air usually above the general ground level. Clouds are the most important form of suspended water droplets caused by condensation. There is no precipitation without clouds.

11.1. Measuring Instrument

The cloudy hours are measured with the help of eye or sensory parts of the body. No particular instrument is required for cloud amount or cloud cover measurement in the sky.

Abstract

A total of 30 groundwater samples were collected in four different seasons (Pre Monsoon, South West Monsoon, North East Monsoon and Post Monsoon) from the coastal aquifers of Kalpakkam region of Tamilnadu. The samples were collected covering the seasonal and lithological variations to infer the influence of natural geochemical processes and anthropogenic sources on the groundwater chemistry. The collected samples were analysed for the parameters like EC, pH and Major ions. The saturation index of silicates and carbonates shows that state of saturation to over saturation, but the sulphate minerals is dominantly under saturated. In the inverse modeling three models are obtained using PHREEQC and the error percentage is noted as 7.45%.

Abstract

Deduction of overindulgence fluoride (F)  from the water has been endeavor by numerous investigators by using different materials both natural and artificial. The objective of this paper was to attempt the fluoride removal by using the locally available natural materials such as red soil, untreated charcoal, local powdered brick, fly-ash from Neyveli (thermal power plant) and mineral serpentine were used, adopting column method. Maximum defluoridation occurs immediately after the experiment has started. The morality of fluoride removed per gram is more in red soil when compared to the other materials. Variation of fluoride removal with time was studied after the erection of the column /unit, the defluoridation setup was then connected to the public water supply from the overhead tank of 50,000L capacity. Higher F removal was noted when flow rate was lesser. An attempt on the regeneration of the fluoride adsorbed soil was also made.

Abstract

Coastal aquifers are the sources of freshwater which are being over extracted due to increase in population, agriculture and industrial activities. This over exploitation has resulted in decline in groundwater level and intrusion of sea water into the coastal aquifers making it unfit for human utilities. An attempt has been made in the coastal tracts of Pondicherry region using Electrical resistivity imaging. The survey has been attempted in six locations spread thought the study area and the interpretation has been attempted by RES2DINV software. The profile length attempted was between 150 to 300 m with electrode spacings between 5 to 10 m. The apparent resistivity ranges between 0.1 to 1183 & ohm. Sea water intrusion was prominent along the northern parts of the study area and lower resistivity isolated in kirumambakkam has been interpreted as salinity due to the presence of clay minerals. In nallavadu saline intrusion has been identified at shallow depth.

Abstract

A study on the Subsurface groundwater discharge (SGD) in the coastal Cuddalore region of south east India has been carried out. Measurement of surface water Radon, Water level, Electrical Conductivity (EC) and pH for a total of twenty four hours, by hourly interval the measurement has been calculated and promote correlated with tidal values calculated by WX Tide 32 software. The SGD measurements were made by using a modified seepage meter. The study reveals a match with water level variation and tide with minor variation due to influx of surface water. Saline discharges, fresh groundwater discharges and surface water mixing processes were identified along the coast. Lower SGD (37.24 – 79.16 cm/day) were observed during fresh groundwater discharge.

Pressure of air at a given place is the force exerted against a surface by continuous collision of gas molecules. Pressure may be defined as the force per unit surface area.

Photosynthetically active radiation (PAR) is the radiation in the 400-700 nm wave band. For plants, 400-700 nm wave band of the light spectrum is very useful because of photosynthesis activity in this band. A simple integral relationship exists between the number of molecules changed photo-chemically and the photons absorbed within the requisite wave bands regardless of photon energy. Net photosynthesis rates are found to be almost linearly proportional to the radiation intercepted, which can be measured by line quantum sensor.

Water loss from a plant in the form of vapour is known as transpiration. Loss of water vapour mainly from leaf cells through pores but also from the leaf cuticle and through lenticels of the stem. The resistance to diffusion of water vapour through a plant’s stomata is called as stomatal resistance. Whereas, stomatal conductance is a numerical measure of the maximum rate of passage of either water vapour or carbon dioxide through the stomata, or small pores of the plant.

Evapotranspiration (ET) is the combined loss of water from vegetation and soil. When water is not a limiting factor at a site, the rate of ET is primarily controlled by meteorological factors like solar radiation, temperature, wind and relative humidity. The measurement of ET under natural conditions is of great importance in the water resource management and irrigation planning. Potential evapo-transpiration (PET) is the evaporation from a surface if water was never a limiting factor. PE-can also be calculated using empirical formulae.

Abstract

A study on colloids in groundwater and its relationship with the geochemical parameters is reasonably essential because of its facilitating nature to transport radionuclides in groundwater. Colloid sampling has been carried out in the coastal aquifers of southeast coast of India. Two different bore wells were selected based on the distance from the coast to collect groundwater samples. On the basis of the result achieved from this study, a reliable representation is emerging. The values of pH and EC are governed by the different size fraction of colloids. In this study, the relation between different size fractions of groundwater colloids and its pH, TDS and EC were carried out. These parameters were analyzed in the lab and its influence with four fractions of colloid like 1.2, 0.8, 0.45 and 0.22 µm have been discovered by smooth scatter plot. The accumulation of particles weighting by normal weighing instrument. There is an higher accumulation of particles found in Kalpakkam than Anupuram in all the size fractions. For separation of particles high frequency pressure was used by ultrasonic cleaner had been carried out. This method is very simple and more reasonable than any other methods.

Abstract

In Gadilam river basin, groundwater is found in both hard rock and sedimentary terrain and is the most important source of rural/urban drinking water supply. Gadilam river basin has gained its importance due to the presence of Neyveli Lignite open cast mine (NLC), group of industrial estate (SIPCOT), extensive depressurization of Cuddalore aquifer and boreholes of New Veeranam Scheme (NVS) in the downstream of the basin. A total of 178 water samples were collected in four different seasons at various lithologies. The collected samples were analyzed for various physico-chemical parameters using standard procedures. Geochemical indicators of groundwater were used to identify the chemical processes that control hydrogeochemsitry. Interpretation of hydrogeochemical data suggests that leaching of ions followed by weathering and anthropogenic impact controls the chemistry of the groundwater. Isotopic study reveals that recharge from meteoric source in sedimentary terrain and rock water interaction with significant evaporation prevails in hard rock region. This thorough understanding helps us to make judicial usage and to maintain the quality of this commodity.

Abstract

The development and management of fresh groundwater resources in coastal aquifers are seriously constrained by the impact of seawater intrusion. The coastal aquifers are fragile and this situation becomes more intense like that of the coastal Cuddalore region. The geochemical signature of groundwater of Cuddalore coast was studied for Pre Monsoon, Southwest, North east and Post Monsoon seasons by collecting total of 64 groundwater samples in each season. The collected samples from were analysed for physical parameters, such as electrical conductivity (EC), pH and major ion concentrations, such as Ca, Mg, Na, K, Cl, HCO₃, PO₄ and SO₄. Interpretation of analytical data shows the predominance of  Na–Cl type   in PRM and Ca- Mg-Cl type  is the dominant facies during POM. The Chaddas evaluation diagram shows that the hydrogeochemical evaluation plot for PRM samples fall in  Na-Cl type. The ratios of Na/Cl and Cl/HCO₃ is also enumerated the fact that the most of the samples from PRM and few samples from other seasons also indicates dominance of salt water intrusion.