Irrigation - Geography for UPSC CSE PDF Download

Table of Contents
1. Methods of Irrigation in India
2. Irrigation Resources and Potential
3. Units and Measurement
4. Classification of Irrigation Projects
5. Command Area Development and Water Management
6. Groundwater Development and Use
7. Irrigation Methods and Technologies
8. Water-Use Efficiency and Conjunctive Use
9. Problems Associated with Irrigation and Their Management
10. Policy, Planning and Modern Approaches
11. Applications and Importance of Irrigation
12. Selected Historical and Statistical Facts (from national assessments)
13. Practical Example: Choosing an Irrigation Method for a Region
14. Annex: World Resources (selected list)
15. Annex: World Agriculture (selected list)
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Methods of Irrigation in India

Main methods of irrigation practised in India are:

• Canals - gravity-fed or diversion systems taking water from rivers and reservoirs through a network of main, branch and distributary canals.
• Wells and tube wells - groundwater abstraction using open wells, shallow tube wells and deep tube wells with pump sets.
• Tanks - small to medium size surface storages constructed across streams or on plateaus to store monsoon runoff for irrigation in the tank command area.

Historically and in present statistics, canals and wells/tube wells each irrigate nearly 40 percent of the irrigated area in the country, while tanks contribute about 12 percent.

Regional Distribution

• Canal irrigation is extensively practised in the Northern Plains - especially in Punjab, Haryana, Uttar Pradesh and Bihar.
• Well irrigation (wells and tube wells) occurs all over India but is especially significant in Uttar Pradesh and the sub-montane regions of Punjab.
• Tank irrigation is common on the Deccan Plateau, particularly in Andhra Pradesh, Tamil Nadu, Karnataka and Odisha (Orissa).

Irrigation Resources and Potential

Surface water and run-off

• The average annual run-off in India's river system has been assessed at 1,869 km3.
• Of this, the utilizable portion is estimated to be about 690 km3.
• Expansion of surface-storage and diversion (major and medium projects) along with canal networks is the main means to harness this utilizable run-off for irrigation and other uses.

Groundwater resources

• The substantial replenishable groundwater potential in the country has been estimated at about 432 km3 (about 43,218.50 million hectare-metres expressed in local unit variants in different studies).
• The total replenishable groundwater in India is often quoted as about 43.18850 million hectare-metres per year (this corresponds to the same order of magnitude as 432 km3).
• About 7.1 million hectare-metres per year is used for domestic and industrial use.
• About 32.47264 million hectare-metres per year is considered available for irrigation.
• According to Central Groundwater Board estimates, about 32 percent of available groundwater resources have so far been developed (figures refer to the assessment date of the quoted study).
• Underground water resources are also given as about 27 million hectare-metres in some sources; of this, about one-third is being used for irrigation in the cited assessments.

Irrigation potential and coverage

• At present only about one-fourth of the net area under cultivation has been provided with irrigation (coverage differs by region and over time as development proceeds).
• The land area that can ultimately be irrigated has been assessed at about 113 million hectares as against a possible gross cropped area of 210 million hectares on full development of irrigation potential.
• With systematic development of irrigation, the irrigation potential has increased from 22.6 million hectares in 1951 to about 102.77 million hectares at the end of 2006-07.

Per-capita water availability

• The per-capita availability of water has declined from about 5,277 m3 in the year 1955 to about 1,970 m3 in the later estimate quoted in the input; this decline reflects population growth together with fixed or slowly changing available water resources.

Units and Measurement

• Hectare-metre (ha·m) - the common engineering unit for irrigable water. One hectare-metre is the quantity of water standing to a depth of one metre over a level piece of land of one hectare area.
• Irrigation potential, storage capacity and groundwater recharge are commonly expressed in hectare-metres (or million hectare-metres) and cubic kilometres (km3); be careful to check unit conversions when comparing sources.

Classification of Irrigation Projects

• Major irrigation projects - large dams and reservoirs; usually cultivate large command areas and supply water to many districts or states.
• Medium irrigation projects - comparatively smaller reservoirs, diversion weirs and associated canal systems serving district-level command areas.
• Minor irrigation schemes - include tank systems, wells, tube wells, lift irrigation schemes, farm ponds and small local structures serving village or farm-level needs.

Command Area Development and Water Management

Command Area Development (CAD) Programme

• A centrally sponsored Command Area Development Programme was launched in 1974-75 to improve utilisation of irrigation potential and optimise agricultural productivity in irrigated areas by integrating land and water management functions related to irrigated agriculture.
• Beginning with 60 major and medium irrigation projects in 1974, the Programme included 314 irrigation projects at the end of 2005-06 with a Culturable Command Area (CCA) of 28.68 million hectares spread over 23 states and two Union Territories.
• The CAD Programme has been restructured and renamed "Command Area Development and Water Management Programme" from 1st April (the input states the date but not the year; the renaming emphasises a stronger focus on water-use efficiency and water management measures within command areas).

Groundwater Development and Use

• Groundwater has been used for irrigation and domestic water supply in India since antiquity.
• At present more than 70 percent of the population uses groundwater for domestic needs and more than 50 percent of irrigation is supplied from groundwater sources.
• Large-scale adoption of tubewells and pumping, particularly after the green revolution, increased cropping intensity and helped agricultural expansion in many regions; however, it also led to localised over-exploitation in several areas.
• Groundwater development requires careful monitoring of recharge, extraction and quality; conjunctive use of surface and groundwater is promoted to improve reliability and sustainability.

Irrigation Methods and Technologies

• Surface irrigation - basin, furrow and border flooding methods; commonly used on flat lands and for crops tolerant of ponding; simplest to design but can be less water-use efficient.
• Sprinkler irrigation - applies water under pressure through nozzles to simulate rainfall; suitable for undulating land, orchards and where uniform application is needed.
• Drip (micro-irrigation) - delivers water slowly at or near the root zone through pipes and emitters; highly efficient, reduces evaporation and deep percolation losses, and is appropriate for high-value crops, orchards, and water-scarce regions.
• Lift irrigation - water is lifted from a lower level (river, canal, well) to fields using pumps; used where gravity supply is not feasible.
• Field-level water management - improved bunding, land levelling, and scheduling of irrigation based on crop water requirements and soil moisture.

Water-Use Efficiency and Conjunctive Use

• Irrigation efficiency is the ratio of beneficial water use by the crop to the total water withdrawn from the source. Improving efficiency reduces wastage and expands effective irrigation without increasing withdrawals.
• Conjunctive use of surface water and groundwater aims to utilise surface water in periods of higher availability while reserving groundwater for dry spells; this reduces stress on a single source and improves reliability.
• Farmers' practices (timely application, crop choice, mulching) integrated with system-level management (canal scheduling, distribution reforms) produce the best gains in productivity per unit of water.

Problems Associated with Irrigation and Their Management

• Waterlogging and soil salinity - prolonged saturation of the root zone and secondary salinisation due to poor drainage and excessive irrigation. Remedies include surface and subsurface drainage, crop rotation, flushing, and controlled irrigation scheduling.
• Groundwater depletion - over-extraction leads to declining water tables, increased pumping costs and deterioration of water quality in some areas. Management measures include regulated extraction, artificial recharge, conjunctive use and promotion of micro-irrigation.
• Water distribution inequity - shortages or unequal distribution within a command area can be addressed by canal lining, improved distributary regulation, volumetric water pricing and participatory water management institutions.
• Environmental and social impacts - large dams and irrigation projects can displace people, alter ecosystems and riverine habitats; proper impact assessment, rehabilitation and ecological mitigation are essential.
• Institutional and operational constraints - inadequate maintenance of canals, poor operation, and insufficient farmer participation reduce the benefits of investments; institutional reforms and capacity building are necessary.

Policy, Planning and Modern Approaches

• Policy emphasis has shifted towards improving water-use efficiency, promoting micro-irrigation, strengthening groundwater regulation, and encouraging participatory irrigation management (water users' associations and farmer organisations).
• Integrated watershed management, rainwater harvesting and recharge structures complement large irrigation systems by restoring local hydrology and enhancing groundwater recharge.
• Technological measures such as remote sensing, GIS-based command area management, drip and sprinkler subsidies, and precision scheduling support efficient planning and operation of irrigation systems.
• Economic instruments - volumetric pricing, irrigation service fees and incentives - help moderate demand and improve resource allocation when implemented with social safeguards.

Applications and Importance of Irrigation

• Irrigation stabilises agricultural production by reducing dependence on rainfall and enabling multiple cropping and higher cropping intensity.
• Irrigation contributes to food security, rural employment, agro-industry and overall economic development.
• Properly managed irrigation supports sustainable agriculture, conserving soil and water resources while maintaining or improving crop yields.

Selected Historical and Statistical Facts (from national assessments)

• Irrigation potential expanded from 22.6 million hectares in 1951 to about 102.77 million hectares by the end of 2006-07.
• Of the assessed river run-off (1,869 km3), about 690 km3 is estimated as utilizable; additional development of storage, lift schemes and inter-basin transfers are methods to increase utilisation within ecological limits.
• Groundwater replenishable potential is estimated at about 432 km3; about one-third of this potential had been developed at the time of the cited assessment.
• Projected ultimate irrigable area has been assessed at 113 million hectares compared with a possible gross cropped area of 210 million hectares.

Practical Example: Choosing an Irrigation Method for a Region

• For a flat alluvial plain with reliable canal supply and rice cultivation, surface/basin irrigation from canals is efficient if canals are well-maintained and distribution is equitable.
• For a semiarid plateau with deep soils and orchards, drip irrigation conserves water and increases water-use efficiency for high-value crops.
• In an area with abundant shallow groundwater and small farms, tube wells combined with regulated pumping and conjunctive use can improve cropping intensity - provided groundwater recharge measures are also implemented.

Annex: World Resources (selected list)

Annex: World Agriculture (selected list)