eChapters

Introduction

R language is a popular and versatile tool for hydrological data analysis and visualization, offering several powerful packages for handling and analyzing hydrological parameters such as river flow, precipitation, groundwater levels, and water quality parameters. R language provides a wide range of statistical functions for hydrological parameter analysis, including time-series analysis, frequency analysis, trend analysis, and regression analysis. Moreover, R’s powerful graphics capabilities make it possible to create high-quality and customizable visualizations of hydrological data. In addition to its statistical and graphical capabilities, R also offers a wide range of packages for data manipulation and cleaning, making it a powerful tool for preprocessing hydrological data. R’s ability to handle and analyze large datasets also makes it well-suited for processing and analyzing large hydrological datasets. Furthermore, R has a strong community of developers and users who regularly contribute new packages and tools, providing a constantly evolving stage for hydrological analysis. Overall, R is a versatile and powerful tool for hydrological data analysis and visualization, offering numerous capabilities and resources for informed decision-making in water resources management and related fields.

Introduction

An integrated approach to understanding the changing dynamics in water resources involves taking into account various factors that influence the management of water resources under changing climatic conditions (Pahl-Wostl, 2007). It is a holistic approach that combines different disciplines, including hydrology, climatology, ecology, geography, and social sciences, to develop a comprehensive understanding of water resources. The integrated approach is essential for several reasons, including addressing climate change impacts, sustainable management of water resources, enhancing water security, addressing water quality issues, and promoting collaboration among stakeholders. Climate change is causing alterations in precipitation patterns, melting glaciers, and changes in river flows, affecting water availability and quality. An integrated approach helps in understanding the climate change impacts on water resources and developing adaptation strategies (Asif et al., 2023).

A brief description of IGMC is given in Para 6.6 with details of the canal sections. Here an attempt is made to review the hydraulic performance of the Main Canal.

7B.1 Study of Flow Characteristic of the Main Canal

The main canal is designed for a maximum discharge of 524 m3/s at head i.e. at Km. 0. Large of number of branches, distributaries and minors off take from the main canal at different location all along the canal. These are shown in the L- section, Figure 7B.1 and a statement off taking canals is given Table 7B.1. Many distributaries such as lift canals have been planned subsequently. Also discharges of few off taking channels have been changed. A clear and updated data are not readily available. So data available are indicated in the Table and plotted in the L - section. A half bottom plan of the canal is also shown in Figure 7B.2

6.0 General

No lessons can be drawn without the experiences of the past. In fact, much of engineering, rather all sciences have developed in bits and pieces from the experiences of the past. The engineers by and large have never become wiser in one day. They have become wiser slowly and slowly with their own experiences and from the experiences of past engineering works. Wisdom lies to gain wisdom from experiences/draw lessons from the marvellous engineering works constructed so far. It helps us in a direction for further development of technological skills.

Here an effort is made to draw lessons from experiences of the canals constructed in the past.

 There are several aspects of such experiences. A few important aspects of studies are:

 (i) Internal hydraulic sections of the canal with respect to discharge, topography, stability of side slopes, type of lining, operation and maintenance problems and their solutions etc.

 (ii) Design of canals banks (embankment) with respect to discharge, depth of flow, depth of cutting /filling, below/above natural ground level, type of soil, topography, operation and maintenance, drainage of banks etc.

 (iii) Canals aesthetics and arboriculture

 (iv) Other utility/service of canal such as multi-objectives of hydropower, irrigation, drinking/industrial water supply, social needs of recreation, forests etc.

A. Rectangular Canals

5.1 Design of Best Rectangular Canals

After the Mehboob and Trapezoidal canals, next best section is rectangle. This section is also generally adopted for small discharges say upto 10 cumecs (350 cusecs). This section ranks at No. 4. Yet, this is the only section most commonly adopted for flumes of discharges upto140 cumecs (5000 cusecs). Typical example is Orsang acqueduct, 1 km. long for 1140 cumecs (40000 cusecs) in ractangular sections on Narmada Canal Project, Gujrat, India, built in the years from 1990 – 2000. Such sections are common in power house canals due to limitation of space and very sharp curves. It is free from the effect of change of side slopes as in the trapezoidal canals (see para 3.3) Still some small side slope (batter) is adopted in thick masonry / concrete lining. It adds to structural stability with economy in thickness of wall and as well as hydraulic efficiency. It may still be called as rectangular section.

Details of its hydraulic efficiency in comparison to semi circle, Mehboob and trapeziodal sections are discussed in chapter 1, para 1.8

A canal of more than 80 cumecs (3000 cusecs) approximetly may be called as a high capacity canal.

It has already been pointed out in chapter 1, that for the best section of any shape, R is always equal to d/2 only, and such depth is the most optimum depth. But such channels are not always practical or most economical due to many other practical reasons, (see para 4.1 and 6.3) and many times shallower depth then this depth is adopted. Typical examples are lining of existing earthen channels, given in para 6.3.

All the best sections have fixed ratio of dimensions very near to the semi circle. For large discharges, radius of semi circle increases that, means depth of canal as well as velocity increases. But higher velocity is not permissible with every type of lining (see table 2.1 and para 2.3). Similarly depth also has limitation of construction, maintenance, stability of slopes, etc. see example–4.2.

Because of limiting velocities and depth, deeper canal section are not practically feasible/possible. Therefore for large discharges, say more than 100 cumecs, Mehboob or best trapizodal sections are just not possible/practical, and recourse has to be taken to trapezoidal section with increased bed width then depth. This section is hydraulically inefficient or uneconomical. Larger the B/D ratio, larger is the inefficiency and section is more costly. (For Mehboob Section, B:D ratio is zero and for best trapizodal section it is much less than 1, see para 3.1, table 3.1 para 3.5 and table 3.4).

A canal of approximate discharge of less than 80 cumecs (3000 cusecs) discharge may be called a medium or low capacity canal).

3.1 Mehboob Section

A Mehboob Section is only a modification of best trapezoidal section by making its complete bottom circular as shown in figure 3.1. Also see figure 1.6 and para 1.7. That is why these canals are also known as canals of zero bed width, or trapezoidal canals with curved bottom, or cup shaped canals.

But these cannot be called as triangular canals with curves, as often spoken. In fact it is a truncated triangle circumscribing the semi circle. Trapezium is also a truncated triangle circum scribing a circle.

More accurately it can be said as a combination of semi circular and best trapezoidal section so as to take full advantage of their hydraulic efficiency and practicability.

This is such a beautiful section that the designer can never commit a mistake, even if he wants to commit a mistake. The dimensions are so geometrically fixed that no one can play with any dimension.

The value of this section was realised for the first time by Er S I Mehboob (1943) in his Punjab Irrigation Branch Paper No.260" Lining of Canals". There after this canal section became well known as Mehboob Section after his name. He also stated that the most economical section i.e. the maximum area for the minimum perimeter is when the centre of the arc is at the full supply line of the section. This is also evident in figure 1.6. This is also the condition for all best hydraulic sections. This section is also useful to a higher silt carrying capacity than a wide shallow one..

Theoritical aspects of design has been discussed in chapter 1. Discharging capacity of canal is

 computed by Manning Equation (1)and continuity Equation (2) (Para 1.4).

 In the Manning's equation  V  =   R2/3  S1/2 / N (Eq. 1, Para 1.4);  N and R play most important role.

 The effect of  R has been discussed in para 1.4.1, Chapter 1. In this chapter the complexities of Manning's n (or N, also known as Manning's rougosity coefficient

 or simply rougosity coefficient) and some practical aspects of composite sections and velocity in best

 Mehboob, trapezoidal or rectangular sectioned channels are discussed.

2.0 Manning's Rugosity Coefficient (n)

Value of N depends upon a number of factors such as , surface roughness, vegetation, obstructions, type of lining, age of lining, erosion and damages in lining, curves, discharging capacity , perimeters, depth of flow, velocity etc. These are discussed below and commonly adopted values of n are given in tables 2.1 to 2.3.

1.0 General

 The design of canal involves following three major aspects:

 A Irrigation and drainage canal network planning.

 B Determination of discharge / capacities of  canals and drainages.

 C Determination of shape and size i.e. geometrical dimensions of the proposed canal section, generally

 known as design of canal section. More appropriately it can be called as design of internal section

 of canal. It can be further divided in three following parts viz.

 i. Design of unlined canals:

 ii. Design of lined canals: or a canal may be partly lined and partly unlined.

 iii. Choice between the unlined and lined canals. This aspect should be distinguished from the selection of type of lining. However, the scope of choice of lining may include both the aspects.

 The design of canal section remains incomplete without the design of its embankments, either in lined or unlined canal, so the next aspect is

 iv. Design of canal embankments. Still to complete the design of a canal one more aspect is required i.e.

 v. Canal aesthetics and canal arboriculture.

10.1. Introduction

Irrigation facilities are created by the Government at huge cost for supplying water to the farmers for raising crops to increase agricultural production. The major and medium irrigation projects are planned, constructed, managed, operated and maintained by the Irrigation Departments, wherein certain procedures and rules are evolved and followed to the delivery schedule of canals, frequency of supply and distribution of water to the farmers, and closing of canals. The creation of such facilities resulted in ushering the green revolution in the sixties and seventies in the production of food grains and also employment generation in the country, thereby improving the socio-economic condition of Indian farmers. However, optimized management of irrigation water is the key to the sustainable development of agriculture and livestock. Since management of water for irrigation is highly location-specific, depending upon agro-ecological and socio-economic conditions, type of irrigation project and land use pattern, it differs from project to project and region to region in the country.

9.1. Introduction

Human dependence on natural processes for the goods and services provided by nature, especially food, fuel and fibre, has been a known fact. In recent times, the value of less tangible services, such as climate control, water f iltration, and soil fertility, as well as recreational and cultural services has been emphasized also. Ecosystem services underpin human existence, health, and prosperity. It has been beneficial to humans through the transformations of resources (or environmental assets, including land, water, vegetation, and the atmosphere) into a flow of essential goods and services like clean air, water, and food (Costanza et al., 1997). Ecosystem services are those functions of ecosystems- including agroecosystems that are useful to humans or supportive of human well-being (Kremen, 2005). Services provided by ecosystems receive little notice for their support to human civilization often leading to poor management of the ecosystems. Land use systems influence ecosystem functions, which determine the supply of ecosystem services. Land and water resources are under considerable pressure from the expansion of cultivated and residential lands. Diverse land use in agrarian landscapes not only fosters biodiversity, but also provides potential ecosystem services such as air cleaning by vegetation, natural water filtration by plant roots, natural pest suppression, soil conservation, nutrient retention, and crop pollination by insects, etc. Lowland floodplains or waterlogged land areas are generally more conscious of the benefits provided by ecosystem services. It is important to create awareness among the people on provisioning services provided by ecosystems, such as crops, biofuel, fresh water, natural medicine, wildlife, and several cultural services. Managing ecosystem services, which link human well-being to conservation outcomes, is essential for achieving the sustainable development goals (SDGs) of the United Nations (Zhang, 2017).

8.1. Biofloc aquaculture

Among the innovations in the field of aquaculture, biofloc technology (BFT) has attracted great attention due to its ability to foster the goals of sustainable aquaculture (Khanjani et al., 2022a). If implemented correctly, BFT capitalizes on the existing organisms in water to significantly reduce water use and environmental impact and increase biosafety at farms (Avnimelech, 2012).

7.1. Introduction

The integrated farming system (IFS) is becoming increasingly important for effective farm resource management in order to increase farm productivity, reduce environmental degradation, improve the quality of life for resource-poor farmers, and ensure sustainability. Integration happens when one production sub-system's outputs (typically by-products) are used as inputs in another within the farm unit (Radhammani et al., 2003; Lightfoot and Minnick, 1991). IFS are a mixed farming system made up of at least two distinct but logically linked components of crop and animal enterprises. The integrated farming system is effective in reducing risk, increasing productivity and revenues, and improving the use of organic waste and agricultural leftovers.

5.1. Introduction

Rice-fallows are a rainfed rice mono-crop production system, where only a single crop (rice) is grown and these lands remain without any crop for the rest of the period of the year (fallow). An estimate shows that rice-fallow areas extended over 22.3 M ha in South Asia, maximum in India ( 88.3%) followed by Bangladesh (8.7%), Nepal (1.4%), Sri Lanka (1.1%), Pakistan (0.5%), and Bhutan (0.02%) (Gumma et al., 2016). The eastern part of India accounts for ~ 84% (9.7 million ha) of the country’s total rice-fallow area (i.e. 11.7 million ha) (Ali et al., 2014; Singh et al., 2017), despite high rainfall during rainy / monsoon season. The reasons are that after the rainy season, irrigation facilities are lacking, very fast depletion of the soil residual moisture due to temperature rise, the poor economic condition of the farmers, and a lack of awareness or knowledge of available technologies. Additionally, delayed harvesting of long-duration rice (150-160 days) results in late sowing of winter crops, which, in turn, exacerbates the temperature and moisture stresses in winter crops (Kumar et al., 2018a; 2018b). Overall, the challenges of growing another crop in rice-fallow areas are the lack of irrigation facilities including declining groundwater levels, the dominance of the long-duration rice varieties cultivation, higher evaporative loss of the residual soil moisture, degradation of soil quality, and poor financial conditions of the farming community with diminishing profit. Recently, climate change with erratic rainfall and delayed monsoon arrival added more challenges for these areas in several places. Deficit soil moisture imposes stress on the crops and negatively affects the winter crops productivity in the rice-fallow system, and several times it results in complete crop failure (Singh et al., 2012; Ghosh et al., 2016).

4.1. Introduction

Globally, rice is cultivated on about 165 million ha of land, which provides around 787 million tons of paddy annually (FAO, 2023). In Asia, 708 million tons of paddy is produced from nearly 143 million rice-cultivated areas. Rice crop is grown in a wide range of climates, varied soil types, and hydrological situations. Rice is the lone cereal crop that grows well in floods.

The rice habitat can be divided into four groups based on the hydrology of the rice field: irrigated lowland rice (79~80 million ha), rainfed lowland rice (54~55 million ha), upland rice (14~15 million ha), and flood-prone rice (11~12 million ha) (Table 4.1) (Bouman et al., 2006).

3.1. Introduction

Rice is grown in varying geographical locations and climatic situations. Most of the rice area lies between the equator and 400 N latitude and between 700 and 1400 E longitude. It grows well from tropical to sub-tropical warm and temperate climatic regions up to 400 S and 500 N of the equator. However, the highest yields are obtained in the region between 300 and 450 N of the equator. The average yield generally increases as the countries are situated further away from the equator (Chatterjee and Maiti, 1985). In India, rice grows in regions from 80 N to 350 N latitudes under widely varying conditions of the land, rainfall, altitude and climatic conditions. It is grown at the sea level in river deltas as in parts of Kerala, as deepwater in states of West Bengal, Assam and Bihar; at high altitudes of 914 to 1524 m or even more as in Kashmir, and in the slopes of the Himalayas. A temperature range of 200 C to 37.70 C is required throughout the life period of rice crop.

2.1. Introduction

Water plays a pivotal role in this earth system. The withdrawal of water for irrigation is about 70% of the global freshwater. Water use efficiency is less than 50% in many countries. It has been forecasted by the Food and Agricultural Organization (FAO, 2015) that global water requirements will be increased by 50% by the year 2050 to meet the demands of agricultural water use. This is so because food demand will be higher for the growing human population. We have entered into an earth system where everything living has evolved and developed (Cosgrove and Loucks, 2015). There has been a new geological scenario, some say Anthropocene (Crutzen, 2002; Williams et al., 2011). Consequently, freshwater will increasingly be a scarce and the costliest resource in the future, which needs to be managed properly.

1.1. Introduction: India’s present population, growth rate & projections

India is the second-most populous country in the world after China with its population of about 1.38 billion in the year 2020. The Population Division under the Department of Economic and Social Affairs, of the United Nations, has projected the country’s population to be growing to about 1.50 billion by the year 2030, and 1.64 billion by 2050, of course with its decreasing annual growth rate from 1.04 to 0.25% or so during the period of next thirty years (Fig. 1.1; UNDESA, 2019). The projection says the Indian population will exceed China by the year 2030 even with its decreasing rate i.e. India will be the most populous country by then. As agriculture and allied sectors are the backbone of this country and the largest livelihood source, it support this growing human and livestock population with diversified natural resources and varied agro-climatic conditions. However, the sustainability of agricultural production should be maintained in the face of perturbation and stress on the agro-ecosystem especially the degraded natural resource base and changing climate.

6.1. Introduction

The growing human population presents a number of issues, including food scarcity, malnutrition, inadequate natural resources (land and water) for agricultural production, and environmental deterioration (MacDonald, 2010). Today, viable intensification of agri-production systems can fulfill rising food, nutrition and environmental demands (Pretty and Bharucha, 2014). Production of rice (Oryza sativa L.), a vital element of food security, which feeds nearly half of the world's population, occupies 143 million hectares of land (FAOSTAT, 2023), and uses up to 90% of all irrigation water in Asia (Liu et al., 2018). For instance, it has been determined that systems for producing rice are one of the main industries that wastes water resources and greatly increases greenhouse gas emissions (FAO, 2013). Therefore, it is necessary to look for ways to manage the rice production system more effectively. In paddy rice systems, co cultivating aquatic animals (fish, shrimp, crab, shellfish, and ducks) and rice has been suggested as a way to reduce the risks of environmental pollution/ contamination linked with rice production while simultaneously optimizing the use of land and water resources to provide humans with both grains and meat (Hu et al., 2016; Ahmed and Garnett, 2011). Co-culture systems have drawn more interest recently due to their potential to reduce the stresses associated with environmental and food insecurity.