Irrigation and Hydropower of Telangana | Telangana State PSC (TSPSC): Preparation Course - TSPSC (Telangana) PDF Download

Hydroelectric Power — what is it?

• It is a form of energy... a renewable resource.
• Hydropower provides about 96 percent of the renewable energy in the United States. Other renewable resources include geothermal, wave power, tidal power, wind power, and solar power.
• Hydroelectric powerplants do not use up resources to create electricity nor do they pollute the air, land, or water, as other powerplants may.
• Hydroelectric power has played an important part in the development of the electric power industry.
• Both small and large hydroelectric power developments were instrumental in the early expansion of the electric power industry.
• Hydroelectric power comes from flowing water... winter and spring runoff from mountain streams and clear lakes.
• Water, when it is falling by the force of gravity, can be used to turn turbines and generators that produce electricity.

How Hydropower Works

• Hydroelectric power is derived from the movement of water.
• It can be considered a type of solar energy since the sun drives the hydrologic cycle, which is responsible for the presence of water on Earth.
• In the hydrologic cycle, water from the atmosphere falls to the Earth as precipitation.
• Some of this water evaporates, while the rest either seeps into the ground or flows over the surface as runoff.
• Water from rainfall and melted snow eventually collects in various water bodies where evaporation occurs continuously.
• Moisture that seeps into the soil can turn into groundwater, some of which feeds into water sources through springs or underground streams.
• During dry periods, groundwater may move upwards through the soil and return to the atmosphere through evaporation.
• Water vapor rises into the atmosphere through evaporation, forming clouds, and some of it returns to Earth as precipitation, completing the water cycle.
• Nature ensures that water is a replenishable resource.

Dams

• Height of a dam and the mass of water behind it are crucial factors that determine the useful energy harnessed.
• Efficiency levels in dams are notably high, ranging from 80% to 90%, showcasing excellent conversion of potential energy into electrical energy.

Irrigation

Classification of Irrigation Projects

• Major Projects These expansive projects involve significant surface water bodies, storage reservoirs, and flow diversion structures, typically catering to areas exceeding 10,000 hectares.
• Medium Projects Medium-scale projects characterized by moderate storage and diversion structures, serving areas ranging from 1,000 to 10,000 hectares.
• Minor Projects Smaller in scale, these projects cover areas below 2,000 hectares, relying on water sources like groundwater, wells, tube wells, or surface water from pumps or tanks. They may also utilize water from tanks for irrigation purposes.

The major and medium irrigation projects undergo further classification based on specific criteria.

• Direct Irrigation method
• Storage Irrigation method

Each of the two classifications is explained in subsequent sections. But before that, it may be worthwhile to discuss here a few terms related to irrigation projects which may also be called irrigation schemes.

Direct and Indirect (Or Storage) Irrigation Methods

Direct Irrigation Method

In the direct irrigation method, water is diverted straight from a river into a canal through a diversion structure like a weir or barrage built across the river. This structure includes some pondage to manage diurnal variations in water flow.

• Effect on River Water Level: This method results in an increase in the river's water level, allowing it to flow into the offtaking channel by gravity.
• Controlled Flow: The flow in the channel is typically regulated by a gated structure. The combination of this structure with the diversion structure is sometimes referred to as the headworks.

Storage Irrigation Method

In the storage irrigation method, water is stored before being used for irrigation purposes.

• Necessity of Storage: This method involves storing water in reservoirs or tanks before it is channeled for irrigation.
• Regulation: The release of water for irrigation is controlled to ensure optimal usage in agricultural fields.

Types of Irrigation Schemes

• One type of irrigation scheme involves storing excess water from a river during the monsoon in a reservoir located upstream of a dam. This stored water is then utilized for irrigation purposes. This method is typically employed when the river's flow exceeds the needs of crops during a certain period but is insufficient or absent during the rest of the year.
• Construction of storage reservoirs is feasible in regions with uneven topography, making it a common practice in non-deltaic areas.

Irrigation Project Structures

Various structures are essential for the successful execution of an irrigation project. These include:

Storage Structure and Appurtenant Works

• Dams
• Spillways and energy dissipators
• Sluices and outlets

Diversion Structure and Appurtenant Works

• Barrage (weirs are now less commonly used for significant projects)
• Canal head regulator
• River training works
• Canal water conveyance structures
• Canal sections and layout
• Cross regulators
• Drops
• Turnouts

Surface Irrigation Methods

• In surface irrigation, water is directly applied to the soil from a channel at the upper end of the field.
• Properly designed water distribution systems are necessary to control water flow and ensure uniform distribution over the field.
• The flooding method is a type of surface irrigation where water covers the land in a continuous sheet. The depth of water applied should be enough for the soil to reach field capacity.
• An appropriately sized irrigation stream is crucial to balance soil intake rate, water storage in the root zone, and ensure uniform saturation of the soil.
• Historically, flooding methods have been used in India without control, known as uncontrolled flooding.
• Water is directed into fields near rivers during floods, leading to uneven water distribution and inefficiency, with potential water wastage and soil erosion on steep slopes.
• Despite its drawbacks, uncontrolled flooding is a cost-effective method of irrigation.

Controlled Flooding Method

Controlled flooding is utilized in two main irrigation methods:

• Border Irrigation: Water is applied at the borders of fields, allowing it to flow across the field gradually.
• Furrow Irrigation: Water is directed through furrows between crop rows, ensuring a controlled flow and distribution.

Irrigation Methods

As agriculture practices evolve, different irrigation methods are employed to ensure optimal crop growth. Two primary methods include:

• Border Irrigation Method
• Basin Irrigation Method

Border Irrigation Method

Border irrigation involves the application of water in a way that inundates or floods the land temporarily. This method is particularly useful for crops that benefit from having water near their root zones. Key points about border irrigation include:

• Borders are long, evenly graded strips of land separated by earth bunds.
• An even surface is created for water to flow down the slope uniformly.
• Each strip is irrigated independently by introducing a stream of water at the upper end.
• Water spreads down the strip in a sheet confined by border ridges.
• Proper leveling of borders is essential for the uniform advancement of the water front.

Additionally, border irrigation can be modified based on land slope, with contour border irrigation being one such method.

Basin Irrigation Method

Basin irrigation is another technique where water is applied directly to the basin surrounding the crop roots. This method offers several advantages and characteristics:

• Basins are created around the plants to hold water.
• Water is directly supplied to the root zone, minimizing wastage.
• It is particularly suitable for crops that require controlled water application.
• Basin irrigation promotes water conservation and efficient nutrient uptake by plants.

By understanding and utilizing these irrigation methods effectively, farmers can enhance crop yield and promote sustainable agricultural practices.

Furrows Irrigation Method

• Furrows are narrow channels that transport water along the land slope between crop rows.
• As water flows down the slope, it seeps into the soil. Crops are typically cultivated on ridges between these furrows.
• This technique is ideal for row crops and plants sensitive to excess water exposure, lasting around 12 to 24 hours.

Subsurface Irrigation Techniques

• Subsurface irrigation involves supplying water below the ground surface directly to plant root zones.
• Benefits include reduced evaporation losses and minimal interference with surface cultivation activities.
• Water is applied underground through two methods: natural sub-surface irrigation and artificial sub-surface irrigation.

Sprinkler Irrigation System

• Sprinkler irrigation mimics natural rainfall by evenly distributing water over the land surface precisely when required and at a rate lower than the soil's infiltration capacity to prevent surface runoff.
• This method involves conveying water through a network of pipes, often using pumps, which is then dispersed into the air through sprinklers. The water breaks into small droplets that descend to the ground.
• It is well-suited for uneven terrains, regions with limited water resources, sandy or shallow soils, or where uniform water distribution is essential.
• Unlike surface irrigation techniques, sprinkler systems do not necessitate land leveling.
• However, sprinklers are not ideal for crust-prone soils.
• Water supplied through sprinkler systems must be devoid of suspended particles to prevent nozzle blockages.

Drip Irrigation System

• Drip Irrigation system, also known as trickle irrigation, involves slowly dripping water onto the soil at low rates (2-20 litres per hour) through a network of small diameter plastic pipes equipped with emitters or drippers.
• This method targets water application near the plants, ensuring that only the necessary part of the soil where the roots are located gets moistened. This is unlike surface and sprinkler irrigation, where the entire soil profile is wetted.
• Unlike other irrigation methods, drip irrigation requires more frequent water applications. This frequent watering schedule helps maintain a consistently high moisture level in the soil, creating optimal conditions for plant growth.

Telangana Micro Irrigation Project

The Telangana Micro Irrigation Project is an initiative aimed at promoting efficient water usage in agriculture by implementing micro-irrigation techniques.

• Emphasizing the value of every drop of water, the government prioritizes water security.
• Commitment to completing long-pending irrigation projects promptly.
• Introduction of the 'Pradhan Mantri Krishi Sinchayee Yojana' with the aim of 'Har Khet Ko Paani'.
• Exploring various options, including river linking, to optimize water resources and prevent floods and droughts.
• Promoting water conservation and groundwater recharge through 'Jal Sanchay' and 'Jal Sinchan' techniques.
• Encouraging micro-irrigation for better crop yield with the motto 'Per drop-More crop'.

Telangana State Micro Irrigation Project (TSMIP)

• Initiated in November 2003, the Telangana State Micro Irrigation Project aims to enhance crop productivity through improved water use efficiency.
• Significant progress made with 5.01 lakh farmers covering 4.79 lakh hectares, utilizing Rs. 2074.72 crores by 2013-14.
• Currently, there is a potential area of 10.06 lakh hectares available for micro-irrigation in Telangana State.
• In the year 2014-15, the Micro Irrigation program implemented across 55,630 hectares in the state, including 39,700 hectares for drip irrigation and 15,930 hectares for sprinkler systems.

Annual Action Plan 2015-16

• The total irrigated area in Telangana in 2015-16 was 17.73 lakh hectares, with irrigation sources being Tanks - 1.50 lakh hectares, Canals - 0.90 lakh hectares, and Groundwater - 15.25 lakh hectares, accounting for 86% of the total irrigated area.
• The area covered under Micro Irrigation until 2013-14 was 4.79 lakh hectares.
• During 2014-15, the plan aimed to cover an additional 0.55 lakh hectares under Micro Irrigation.
• The remaining potential area for Micro Irrigation was identified as 9.91 lakh hectares.
• It was estimated that a minimum of 18 years would be needed to cover the remaining area under Micro Irrigation.
• 85% of farmers in the State were categorized as Small Farmers (SF) and Marginal Farmers (MF), relying heavily on Groundwater irrigation.
• The predominant soil types in the region were Chalka and gravel, known for their poor water retention capacity.
• Considering the aforementioned factors, the Action Plan proposed to allocate 1 lakh hectares for irrigation in 2015-16.
• The distribution of the proposed area included 75,000 hectares for Drip Irrigation and 25,000 hectares for Sprinklers Irrigation.
• A subsidy of Rs. 806.25 crores was allocated for the implementation of the plan.

Hydropower Projects in Telangana

Nagarjunasagar Hydroelectric Project