eChapters

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

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.

Common groundwater investigations include necessary considerations of the system’s influx sources, flow regime, discharge points and geomorphological characteristics of the area. Often, hydrogeomorphological mapping of an area is required as to determine these characteristics. The primary data can be acquired from the survey of India toposheet map and the satellite images. The secondary data set includes the satellite imageries, the preparation of digital elevation model (DEM) and digitized precipitation maps.

The first step in the procedure of hydrogeomorphological mapping is to calculate the watershed/basin area, which serves as a mask to define the area of interest. The watershed/basin calculation relies on the digital elevation data and assumes that topographic aspect (dip direction of the cell surface) completely controls the extent to which surface flow emanating from each point in the study area can reach the low point in the valley. The calculation of the potential annual recharge of the aquifer combines techniques described above with data for recharge areas, DEM aspect, and precipitation. First, the catchment area of the recharge zones must be calculated in a process similar to the watershed analysis, returning the area associated with the catchment coded as “1”. A simple multiplication overlay with the precipitation data and the catchment areas yields a result giving the amount of precipitation for each catchment cell. Before using the precipitation data, we converted it to meters so as to keep units consistent. The precipitation amounts within the catchment area (i.e. each cell value) are to be summed, yielding the amount of water available for influx into the groundwater system. Finally precipitation per year data can be acquired.

Identifying surface areas of groundwater discharge is based on the observation that such areas provide a relatively constant source of moisture, which is readily exploited by vegetation in semi-arid region. Thus areas with year-round green vegetation are assumed to be indicators of discharge. The relative amount of vegetation in a scene can be estimated by calculating a vegetation index (Reddy et al, 1989 and Tucker 1979).

The world is head98ing towards a water crisis. Africa and West Asia are likely to be worst affected by water scarcity, but with increasing population, water may fall short even in the other parts of the world. According to the recent UN report, the supply of clean and fresh water is depleting at such an alarming rate in some regions, that within 30 years, about two third of population will suffer moderate to severe water stress.

In hydrogeomorphological context of social environment the water is an essential natural resource for sustaining life. The available water resources are under tremendous pressure due to increased demands. The time is not far when water, which is the free gift of nature, will become a scare commodity. Therefore, conservation and preservation of water resources are urgently required to be done at priority basis. Water management has always been practiced in our communities since ancient times. But such practices have faded away during the past few decades mainly due to lack awareness. Hydrogeologists feel that the water harvesting practices must be urgently implemented to overcome the problem of water crises. In India the Ministry of water Resources is endeavouring to make rainwater harvesting a part of every day life in villages and cities as a people’s movement. Hydrogeomorphological aspect of social environment include (a) Social - Cultural -Administrative Consideration (b) Education and Training in Hydrogeology for Professionals and Technicians (c) Education for Farmers and Women (d) Education for Masses. These are described as below:

The beginning of the 20^th century was heralded by methodological revolution in geomorphological studies brought in by Davis (1899). His classical model of geographical cycle defined by him ‘ as a period of time during which and uplifted landmass undergoes its transformation by the process of land sculpture ending into a low featureless plain (peneplain)’ dominated the geomorphological investigations all over the world throughout 1^st half of the 20^th century.

The statistical techniques by Horton (1932 and 1945) brought quantitative revolution in the field of geomorphology when he presented quantitative analysis of morphometric characteristics of fluvially originated drainage basin. Post 1950 geomorphology has undergone vast change in the methods and approaches to the study of landforms, conceptual framework, paradigm and thrust areas of study. The most outstanding contribution to the advancement of geomorphological knowledge in this period is the adoption of quantitative approach based on deductive scientific method to the study of landforms and processes at short spatial and temporal scales (Strahler, 1956 and Schumm, 1956).

Several attempts have been made in the world in past to classify large territories and landforms into morpho-units. Valuable contributions pertaining to landform analysis have been summarized below: Joerg (1914) subdivided North America into natural regions, Fenneman (1914) established physiographic boundaries and gave physiographic divisions of the United States, whereas Anderson (1941) gave physiographic divisions of Columbia plateau. Howard and Spock (1940) and Weaver (1965) presented the excellent ways of classification of the landforms while Wood and Snell (1960) applied the quantitative systems for the classification of the landforms. However, Linton (1951) and Hammond (1954 and 1965) gave techniques for mapping delineating small scale and large-scale landforms.

Water is a social requirement. Society now become aware about it’s dependence upon water and hence realized the importance of water in sustaining not only the development but also life. Water: too little, too much, too dirty; is general scenario in the world. But with increase in population water become limiting resource and is becoming scarcer and scarcer day by day. As water become scarcer commodity, the users (stakeholders) become more conscious regarding their share in water and ultimately this situation may lead to water conflicts. Earlier water related problems were generally tackled by hydro-engineers, but now in present climate changed scenario these problems go beyond the hydraulics and hydrology. Now a days politicians, ecologists, Non Government Organizations (NGOs), the media and the stakeholders etc are playing a crucial role in decision making in respect to water management issues. Now water projects are designed in reference to social context (Social context means cultural, economic, political, sociological, legal and other such aspects). When social factors are taken into consideration while tackling the water problems, it could not possible to satisfy all involved. Thus it is required to agree upon a compromise solution acceptable to all. Over recent few decades, information and communication technology (ICT) flourishes with great advances. It provides the ways to search for compromise solutions. In this chapter information, hydroinformatics, evolution of hydroinformatics and role of internet in hydroinformatics are discussed.

In this era of computer, mathematical models become integral part of hydrologic studies due to advancement in soft technology. But question always arises as ‘Why should modeling?’ It was well expressed by Rosenblueth and Wiener (1945) as

No substantial part of the universe is so simple that it can be grasped and controlled without abstraction. Abstraction consists in replacing the parts of the universe under consideration by a model of similar but simpler structure. Models, formal or intellectual on the one hand, or material on the other are thus a central necessity of scientific procedure.

Water is fundamental to life, supporting ecosystems, driving economies, and sustaining human well-being. However, the availability of this essential resource is increasingly threatened by hydrological drought, a complex phenomenon characterized by prolonged deficits in surface and subsurface water supplies. Unlike meteorological drought, which is defined by precipitation shortages, hydrological drought manifests as reduced stream flow, diminished lake and reservoir levels, and depleted groundwater, impacting water availability long after the rains have ceased. This chapter looks into the critical aspects of hydrological drought management, exploring the multifaceted nature of this challenge and outlining strategies to mitigate its devastating consequences. We will navigate the intricate web of factors that contribute to hydrological drought, from climatic drivers to the profound influence of human activities. Understanding these causes is paramount to developing effective management approaches.

Groundwater exists at many places beneath the surface of the earth. It is normally hidden from view but, on occasion, can be seen flowing from springs and wells or seeping into tunnels. Certain properties of the various geologic materials control the ability of groundwater to enter into, move through, be stored in, or be extracted from the ground. Therefore, an understanding of geology is necessary in order to gain an understanding of groundwater found within a particular area of investigation. A basic part of the study of the geology of an area includes the preparation of a map showing surfacial exposures of each rock type. Interpretation of the map facilitates the study of the underground configuration, characteristics, and physical properties of these materials. This, in turn, enables the evaluation of groundwater storage, movement, and yield, as well as the identification of areas of ground water quality problems, recharge, and extraction.

The fundamental unit of a geologic study is the geologic formation. A formation has been defined as any assemblage of rocks, which have some character in common, whether of origin, age, or composition. In this sense, the term “rock” is defined as any naturally occurring part of the earth’s crust, made up of aggregate of minerals and includes hard, dense granite, lava ash, clay, sand, and even loose-uncohesive soil.

Abstract

Geochemical processes occurring within the groundwater and reactions with aquifer minerals have a profound effect on water quality. Hydrogeochemical composition of groundwater can also be indicative of its origin and history of passage through underground materials which water has been in contact. Assessing groundwater quality and developing strategies to protect aquifers from contamination are necessary aspects for proper planning and designing water resources. Anthropogenic activities like explosion of population, industrial growth, inputs of fertilizer, pesticides, and irrigation has been a crucial factor for determining the quality of groundwater. In this scenario, 43 groundwater samples were collected from the Dindigul district of Tamilnadu, a Hard rock terrain. The samples wereanalyzed for major cations and anions along with heavy metals to derive the different quality parameters and to obtain the pollution indices of different samples. This study focuses to find out the spatial relationship between the analyzed fluoride concentration in groundwater and pollution indices derived from the heavy metal concentration in the groundwater of the study area and their variation with respect to season.

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.

The sensors present over remote sensing satellites are designed to collect energy or radiance from the varied surface features having wide range of radiance i.e. from features like water bodies having very low radiance to features like sand or snow having very high radiance. But, most of the time, the study area may not have all these features; therefore, radiance values may remain confined to a narrow range. This reduces the contrast of the image, thereby decreases its visual quality. In this context, image contrast enhancement techniques are used for effective visualization and display of remote sensing image on computer screens or hard copy so that maximum amount of information can be derived through its visual interpretation.

Contrast enhancement of a digital image is a technique to modify the original grey levels of input image to the entire available range of the grey levels. This increases the contrast between various features in the image which improves the visual quality of original image. Contrast enhancement can be done by both linear and non-linear methods. Some of the commonly used contrast enhancement techniques with their implementation in R software are discussed in this chapter.

We need following packages for performing this exercise in R. raster package is required for importing of raster image and for performing contrast enhancement. RStoolbox package is also required for contrast enhancement as well as for visualization of raster data with ggplot2 package. rasterVis package is mainly used in this exercise for plotting histogram of the raster data.

The information of image is perfectly accepted by eyes when the image will be in convenient form. Always pictures accurately detail about information related to their position, sizes and inter-related with each other is objects. Actually images portray positional information which can be recognized as objects. Human eyes are exact example for differentiating that information from images to innate visual and mental ability.

1. Introduction
Global food security threatened by climate change is one of the most important challenges in the 21st century to supply sufficient food for the increasing population on diminishing agricultural land while sustaining the already stressed environment. Global agricultural production is highly vulnerable as key crops such as maize, wheat, rice, and legumes will be negatively affected by climate change. The study showed that each degree Celsius increase in global mean temperature is estimated to reduce the average global yield of cereal crops by 6-15%. Further, predicted changes in climate may affect water availability and key soil processes such as respiration and nitrogen (N) mineralization, thus key ecosystem functions such as carbon (C) storage, nutrients, and water availability. Although crop growth simulation models are being utilized to understand the impact of climate change scenarios on aboveground biomass, the roots and their architecture, which are essential for plant adaptation and productivity, need to be studied more due to the difficulty of observing them during the plant life cycle. The root system and its architecture are highly responsive to external environmental conditions such as soil moisture, nutrients, temperature, pH and microbial communities; therefore, it is high time to study below-ground responses to future climate scenarios. The study of plant roots represents a highly promising yet underexplored area of research related to plant growth. While the aerial parts of plants have received significant attention due to their visibility and accessibility, the underground portions have been largely overlooked due to the challenges in observing and sampling them and the disruption caused when roots are removed from the soil. Plants’ efficiency of water and mineral nutrient uptake largely depends on how effectively new root tips penetrate soil horizons and how these roots eventually die and decompose. The plant’s ability to access soil resources depends on the size of its root system and the activity of its growing root tips. Root growth is influenced by both genetic factors and environmental conditions. For example, fine root dynamics vary with the seasons, with increased vegetative growth and nutrient release occurring during the monsoon months. (Kumar et al., 2020). Further research is needed to assess how different tillage and water management practices affect rooting behaviours, soil water extraction, and nutrient uptake.

Introduction

Climate change refers to change of weather variables over a long period of time. The Inter-Governmental Panel on Climate Change (IPCC) defined climate change as a “change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer”. This may occur due to natural variability or as a result of human activity. The change may be in the form of magnitude or variability of a single or multiple weather variables or weather phenomena. Global shift in temperature and precipitation pattern as well as increasing frequency of extreme weather events are consequence of climate change which is perceived over several decades. Climate change is indeed increasingly recognized as a considerable risk to agriculture particularly with respect to direct impact on crop production and yield stability (Barzman, 2015).

Effect of Climate Change in Global Warming and Greenhouse Gases

Global warming as the resultant of climate change has become an issue of serious concern worldwide for existence of life on the earth. Over past hundred years, the global temperature has increased by 0.8⁰C and is expected to reach 1.1-5.4⁰C by the end of next century. Major factors affecting the global warming and the climate change is the concentration of greenhouse gases like carbon dioxide, methane and nitrous oxide. On the other hand, CO₂ concentration in the atmosphere has increased drastically from 280 ppm to 370 ppm and is likely to be doubled in 2100 (IPCC, 2007).

Introduction

Our soil resource is generally taken for granted for many uses. Most people don’t realize the importance of the resource and that it is fundamental for farming/agriculture. Without high quality soils, agriculture production cannot be achieved on a sustainable basis to meet ever growing demand. Thus, conservation agricultural practices are capable of improving soil health by increasing organic carbon, aggregation, improving infiltration and minimizing erosion losses.

Introduction

The main aim of conservation agriculture is to sustain and improve the crop productivity and to provide protection against biotic and abiotic stress, while at the same time protecting and enhancing the biological activities of the soil. The essential principles of conservation agriculture are no-tillage (and direct seeding) or reduced tillage, the maintenance of a cover of live or dead vegetative mulch on the soil surface and the wise use of crop rotations. The crop sequences are planned in such a way that which will discourage the buildup of pests or diseases and will help to optimize plant nutrient use by synergy between different crops of the rotation. While deciding the crop rotation, the locally important crops should be considered and there should be deep rooted and shallow rooted crops in the sequence so that the utilization of soil nutrients is maximized. At least one leguminous crop should be there in the crop sequence. The use of plant residues influences the soil physical, chemical and biological properties by reducing surface temperature, rate of evaporation and maintaining water content, nutrient load and rate of organic matter decay. The soils under conservation agriculture are happened to be highly active and diverse biologically and can supply plant nutrients for a longer period of time because of their higher nutrient loading capacities.

Soil biodiversity comprises of all organisms whether single-cell organisms or multi-cell animals or plants that live in the soil. Soil microbial diversity includes “genetic diversity, that is the amount and distribution of genetic information within microbial species, diversity of bacterial and fungal species in microbial communities, and ecological diversity, that is variation in community structure, complexity of interactions, number of trophic levels and number of guilds (Nannipieri et al., 2003).

Background and Technology Intervention

To increase the water use efficiency coupling piped network and micro irrigation, Department of Agricultural Engineering along with the Tamil Nadu Government introduced a project on “Water conveyance works of modernization of on-farm irrigation network in 5(R) and 7(R) sluices Parambikulam Aliyar Project (PAP)” covering a total area of 109.86 acres in both the sluices.

Significance of this project is to improve the water use efficiency in canal command areas where the farmers were unable to cultivate annual / long term crop due to alternate supply of water in each zone. PAP command area has 4 zones and each zone receives water once in 135 days in a 2 year span through open channel leading farmers to adopt flood irrigation.