eChapters

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.

Aerial photography is objective of getting panoramic view of earth surface to analyze the features of earth and their interrelation at particular time period which may be changed in further events. In this concerned, the observation may play a vital role in achieving the goals of photography. Undoubtedly it is widely used in social function and so on, but still awaited for scientific or research use. Drone can measure the geometry of ground surface at lower altitude with more accuracy in the form of visual feature in natural colour. flight height of drone mainly limits the large area coverage due to lower flying and drone can work perfectly at low altitude planning with good quality feature/photography.

Fundamentally toposheet represents a kind of map in which topographic features of particular area is given details on the map features in two dimensional land surfaces. It shows both horizontal and vertical portion of the terrain with a combination of contour lines, contours, symbols, labels and related representation together in one piece of paper. Toposheet portray the shapes, location of mountains, many natural and manmade features, and the toposheet combinedly uses for extracting accurate information about particular area containing land surface features.

Age old practice of photography was taken with still camera in parallel direction, not aerially scan or snapping which really present wider prospective of any object or places in rearranging or planning skilfully in two dimensional working. Earlier aeroplane played a important role in over head condition to capture snaps but again accuracy and angle of camera limited the works because these photographs were diagonally or trigonally not matched the reality of ground.

Preparation of base map being in mind, the forest, agriculture, water, road and boundary are almost same for all but theme may be different as per requirement. Base information is to survey and need terrain information, the preparation includes land forms by separation of water, kart area, coastal area. Meanwhile preparation of focus might be on DEM (Digital Elevation Model) and water movement helps in demarcation of boundaries on map.

Cartography has much back history than what we seen in portable form by its name or definition. Many prehistoric painting of caves had their own time frame record of maps, artifacts and design have been preserved hoping that they are sufficient to the era of forgotten habit and culture, and treasure explicit ancient world. The ancient wall painting of seventh millenium BC, might have indication of oldest maps in the world and the painting is assumed to be the location of ancient city Antolia as Mellaart, depicted 1967. Onward 600 BC, the modern form of cartography started to develop map. The pioneer contribution in map designing and development, old Greek and Roman were main contributor in this direction. One Greek Philoshopher Ptolemmy, multi-talented genius are recalled in this context, who later credited with first documented map of world during production of Geographica, is a treatise on cartography, very soon one Arabian Scholar Muhammad Al-Idrisi prepared a medieval Atlas involving knowledge of world collected by Arabic merchants in 1154.

GPS stands for Global Positioning System, basically Navstar GPS is a radio based space aviation system developed by United state government which was operated by United State Air Force. It provides geographic location and time related information to GPS receivers under global navigation satellite from anywhere of earth where unobstructed line of sight to 4 or more GPS satellite co-ordinate (Anonymous, 2018). Even GPS not required any user for transmitting data, with working independently on any telephonic or internet receivers; through these technologies we can enhance usefulness of the GPS location based information. The GPS serves as critical positioning capacity to various fields like army operation, civil aviation, and commercial scope to wider scope in around world.

In modem days, many informations receive through electronic media with instant connecting by satellite based information on social, economical, environmental etc. the informations are coded with feasible electronic encrypt and delivered to people. Similarly remote sensing, GIS (Geographical Information System) and GPS (Global Positioning System) also serve world for better understanding the ground reality along with reducing cost of operation, transforming data through electronic webs easily. In earlier phase, ground related information was not easily obtained because all kind of work had been done manually using analog maps of earth; even map draw was done by drafting from totposheet or hand maps, no interface of analog and digital world.

1.1 Introduction
Irrigation is the artificial application of water needed to the crop field. It is the process of uniformly wetting the root zone depth. The wetting may be done over the land surface or below of it. The application of water in excess to the requirement or accumulation of water in crop field due to rain or unplanned seepage is not considered as irrigation. However, irrigation is supplemental to rainfall. Irrigation water is considered as single most important input for crop production.

The purpose of a sub-surface drainage system is to lower the ground water table and removal of salts beyond the crop root zone. The ground water beyond table may rise due to commonly practiced flood irrigation method, seepage from unlined channels, percolation of rain and runoff water and sub-surface flow from higher areas. Sub-surface drainage consists of drains laid at a specified depth, spacing and grade below the ground surface. The size, spacing and depth of drains depend largely on the soil-water properties viz., infiltration, saturated hydraulic conductivity, drainable porosity; and the requirement of removal of water through drains in certain time period fixed on the basis of rainfall and crop cultivated. The drains are usually placed in a pervious stratum. Suitable filter of coarse sand and gravel may be used when it is placed in a low permeable stratum. Sub-surface drainage serves the important job of removal of concentrated salt solution from the crop root zone particularly in arid and semiarid region.

Advantage of sub-surface drainage system

1. Since sub-surface drainage are underground, no loss of land for cultivation. Some part of the land goes out of use for making drains in surface drainage.

12.1 Introduction

Agricultural drainage is the removal of excess water from the farmland for the purpose of providing favorable soil air environment for plant growth. Removal of water may take place form the surface or below the surface of the land. The practice of lowering ground water table below the root zone depth to improve the plant growth or to reduce the accumulation of salts in soil is also called as drainage

Drainage system is broadly classified as surface & subsurface drainage. Removal of excess water over the land surface is known as surface drainage & that of removing water below the surface is known as subsurface drainage. The flow of water in the form of evaporation or evapotranspiration also play important role in improving drainage situation. It gives the idea of the time required to get the wetland workable though it is not called a type of drainage as because this is very slow process & cannot be controlled by the human activities. However, using of certain tree plants e.g., Eucalyptus, Poplar, Casurina or similar species in wet fields, which transpires at high rate and improves the drainage problem by lowering the shallow water table is the new idea known as bio-drainage.

10.1 Land and Water Resource

India has got the world’s 2.45% area and 16.87% of population with only the 4% of available fresh water (Table 11.1). This indicates the necessity of development of water resources and optimal use of it. India at macro level does not have short of water. But the shortage of water is due if not properly managed by conservation and sector wise utilization.

The water resource potential of the country has been assessed by different agencies in different time (Table 11.1). It is observed that the latest estimate of 1869bcm (1993) are within the little variation of the estimates since 1954. The utilizable water resources of the country are assessed 1123bcm by CWC (1993) of which 690bcm from surface water and 433bcm from ground water sources. This 690bcm can be harnessed if matching storage structures are built. The surface water utilizable potential may increase by 220bcm if inter-basin transfer

Poor quality of water is one of the important factors causes gradual accumulation of salts on the ground or in the root zone of crops leads to saline and alkaline condition. This results in loss of permeability, toxicity and anaerobic conditions. In salt affected soils plants face constraint to derive their nutrients at the required rate due to high soil moisture tension, which affects adversely the crop growth and productivity.

10.1 Causes of Salt Problems

The following are the reasons for causing the soils become saline or alkaline.
1. Rise in water table: A rise in water table and high evaporation and transpiration rates with poor drainage lead to build up dissolved salts.
2. Quality of irrigation water: Irrigation water contains the dissolved salts exceeding certain limit cause accumulation of salts in soil profile.

9.1 Introduction

Water is a precious commodity. Necessity of conservation of water supply is increasingly felt all over the world as the demand of it continues to increase when the sources of supply are increasingly scarce. The conveyance and proportional distribution of water is one of the most important part of any irrigation project. Water available in the stream, reservoirs or wells is carried to the field of use through canals. The economy of any irrigation project largely depends on how efficiently the water is being transported and distributed in respect to water losses and cost.

Water losses in irrigation channels are mainly due to evaporation from the water surface and seepage from the bed and side of the channels. Seepage losses some time become the single important factor which causes unavailability of water particularly in downstream of the channel in canal irrigation system and excess pumping of water in tube wells and river lift irrigation system.

Hydraulics of wells means the laws that are applicable to understand the flow of water through the formation and certain aquifer properties that determine the discharge of a well. Darcy’s law is used in studying groundwater flow though Darcy’s law is not valid under certain cases.

8.1  Water Bearing Formation

The earth’s crust is called the lithosphere which consists of hard rocks and disintegrated rock materials. The outer parts of the earth’s crust are porous and containing partially and fully filled up with water. The surface strata of the earth is partially filled with water and is called as zone of aeration and the zone below this which is completely filled with water is called the zone of saturation. The zone of aeration is divided into (i) the soil water zone (ii) the intermediate zone and (iii) the capillary fringe (Fig.8.1).

7.1 General

The major portion of water in a crop field gets lost through evaporation and transpiration. Evaporation is the process by which water is changed from the liquid state to vapor state. It takes place from the adjacent soil, water surface or from the surfaces of leaves of the plants. Transpiration is the removal of water vapour through plant body. Evapotranspiration(ET) is the sum of evaporation and transpiration. The process of evaporation and transpiration goes on simultaneously and difficult to separate them in a crop field.

The term consumptive use is used to refer evapotranspiration together with the water used in the metabolic activities of the crop plants. The actual amount of water used in metabolic activities is insignificant (less than 1% to ET). Therefore, the consumptive use and evapotranspiration are often used as synonymous term. It includes the water consumed by the plants

The plants collect water by its root system available in the soil medium. A soil rich in nutrients cannot ensure success of crops unless the presence of satisfactory state of water and air, mechanical attributes and thermal regime. The physical properties of soil and plants greatly influence the movement, retention and use of water. The soil should provide sufficient pore spaces and size distribution and decomposition of rocks and for the movement and retention of water for plant needs. Rainwater, irrigation, groundwater, seepage, etc., contribute in replenishing the water in dried up soils. In all the cases thorough understanding of behavior of water is required to ensure the need of water to plants and optimize the use of irrigation water.

6.1 Soils

Soil is initially formed by the disintegration and decomposition of rocks and minerals and accumulation of biological residues. Usually the outer layer of the land surface is referred

5.1 Irrigation Channels
Canal or channel is an artificially made conduit through which water is supplied to the field from river, tank, reservoir or wells. The open channel is the most common type of water conveyance system. If the pipes and drains are partially full behave like open channel. The irrigation channel may be lined or unlined and the flow is either uniform or varied.

The canal may be classified in following ways.

a) Classification based on the source of supply i) Permanent or perennial canal ii) Inundation canal

A canal is said to be permanent when it is fed by a permanent source of supply and has permanent networks of distribution of supplies. Inundation canals draw their supplies from river usually when water stage exceeds a predetermined level. Headworks are not provided for diversion of river water to canal. However, canal head regulators are provided to regulate the canal head as required time to time to accommodate the changing pattern of river course.

Scheduling irrigation is the process of determining when to irrigate and how much to irrigate. Selecting the appropriate time span in between two irrigation and applying the required volume of water in each irrigation, ensures saving of water, minimize energy use, higher crop yield and lower production costs. Irrigation applied earlier than due date causes loss of water through evaporation or deep percolation and later causes water stress to plants and thereby affects the growth and yield of the plants.

Scheduling of irrigation may be required in two field conditions: (i) when available of water is adequate, (ii) when availability of water is limited.

In the places where water is adequate scheduling of irrigation follows full   irrigation with time sequence of minimum number of irrigation to ensure maximum yield and high water use efficiency. When water is limited its use is rationalized by using at the sensitive stage

3.1 Introduction
Irrigation efficiency evaluates how effectively the water has been distributed for the purpose of crop production. Water is conveyed to crop field through canal water courses and channels. During this process considerable amounts of water get lost through run off, deep percolation, evaporation, etc. The losses of water greatly depend on the skill of the irrigator, degree of land preparation, and design and planning of the system. The extent of water losses starting to diversion of water from its source to crop field though conveyance and ultimate application and distribution of water in crop field which can be estimated separately. The estimation of these efficiencies enables one to identify the step(s) where improvement is required. The method of measurement and evaluation for its efficiency is prerequisite for proper use of water. Irrigation efficiency in developing countries in general is poor particularly in gravity irrigation methods. However, water is become more and more scarce. Due to pressing need of it judicious and efficient management is one of the vital issues to be solved on priority basis.