NOTESAGRICULTURAL & RURAL DEVELOPMENT

CONJUNCTIVE USE OF GROUNDWATERAND SURFACE WATERBY: THE WATER FOR FOOD TEAM ISSUE 6

FEBRUARY2006Conjunctive water use refers to simultaneous use of sur-

face water and groundwater to meet crop demand.Each day, hundreds of thousands of farmers in canal,tank, and other surface irrigation systems combine sur-face water with groundwater. They do so in an individ-ual manner, uncontrolled by any scheme or basin-levelentity. Conjunctive management, by contrast, refers toefforts planned at the scheme and basin levels to opti-mize productivity, equity, and environmental sustainabil-ity by simultaneously managing surface and groundwa-ter resources. In many systems and basins, such planningis needed to raise crop water productivity.

Conjunctive management occurs when system admin-istrators control ground and surface water simultane-ously. It may be achieved by modifying the configura-tion of the surface system and its operating procedures(Box 1). It is less widespread than conjunctive usebecause it requires institutions and coordinating mech-anisms that few client countries yet have. Conjunctivemanagement is complex and can be controversial.Nevertheless, it can be paramount, particularly in water-scarce regions and in times of drought, because failureto integrate conjunctive water resources can result ingroundwater overexploitation.

Box 1: Benefits of ConjunctiveManagement in Madhya GangaCanal Project, Uttar Pradesh, India

River diversion systems often use lined canalsto remove excess floodwaters during monsoon. However, simple modifications ininfrastructure and the operating system cantransform this waste into wealth. UttarPradesh had a network of disused earthen sur-face drains constructed in the 1950s to controlwaterlogging and floods. After the 1950s,intensification of groundwater use creatednew opportunities for conjunctive manage-ment by building check structures at suitableintervals to promote groundwater rechargewith monsoon floodwaters. In the course of a10-year collaborative study, scientists from theInternational Water Management Institute(IWMI), Roorkee University, the Water andLand Management Institute, and the UttarPradesh Irrigation Department found thatusing these modified drains for monsoon floodirrigation produced the following benefits:

• A 26 percent increase in net farmer income

• A decrease in average depth of ground-water from 12 meters in 1988 to 6.5 meters in 1998

• Annual energy savings of 75.6 million kilowatt hours and pumping cost savings of Rs. 180 million

• An increase in canal irrigation from 1,251hectares in 1988 to 37,108 hectares in 1998

• A 15-fold increase in rice area

• A 50 percent reduction in conveyance lossesin canals

Source: IWMI 2002.

Users of surface irrigation systems install tubewells aspart of a strategy to avoid yield loss caused by unreliablewater delivery. Tubewell irrigation water is costlier butoffers control and helps save input investments. Farmer

FAO/17187/G.Bizzarri

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tubewells raise the productivity of irrigation systems, extendthe area served, and help prevent waterlogging. In some sit-uations, they reduce public investment in drainage by pro-viding vertical drainage. High-income countries have finelydeveloped conjunctive management to even out spatial andtemporal variations in regional water availability (Blomquist,Heikkila, and Schlager 2001).

Since surface irrigation practices directly influence ground-water recharge, improved main system management is keyto conjunctive management of surface and groundwaterresources. These improvements may require changes in theinfrastructure but are more a question of building technicalcapacity, adapting the organizational and institutional frame-work for more efficiency, and improving information andcommunication systems.

Potential Areas of Investment

Five areas of investment opportunities appropriate for differ-ent conditions follow bellow:

RECONFIGURING SURFACE IRRIGATION PROJECTS.Many surface irrigation projects were designed under a slewof antiquated assumptions about cropping patterns andhydraulic infrastructure in the command. Reconfiguring themain system, rationalizing the operating rules and practices,and training system managers to operate the modernizedsystem in a conjunctive management mode offer a majorinvestment opportunity.

GROUNDWATER RECHARGE TO SUPPORT INTENSIVEGROUNDWATER IRRIGATION. A new development in dense-ly populated areas of Asia is intensification of well irrigation inregions where rainfall precipitation is the only source of ground-water recharge. Western and southern India have experiencedthis phenomenon on a significant scale. In those two regionsthe number of groundwater wells has increased from fewerthan 100,000 in 1960 to nearly 12 million today (Shah, Singh,and Mukherjee 2004). With falling aquifers and erratic rainfall,local communities and governments are turning to constructinglocal water harvesting and recharge structures on a massivescale with the primary objective of increasing groundwateravailability for improved drinking-water security, drought proof-ing, and protecting rural livelihoods. Evidence suggests thatthese community-based investments significantly stabilize liveli-hoods in regions that may never benefit from large surface irri-gation projects (Shah 2003), especially if accompanied byinvestments in demand-side irrigation management throughreal water resources savings (Foster et al. 2002).

CONJUNCTIVE USE WITH POOR-QUALITY WATER.Difficulties and costs involved in disposing of wastewateroften present new opportunities for conjunctive use.

Growing wastewater use in periurban agriculture in citiesaround the world are a case in point. Research by IWMI inseveral cities in India, Pakistan, and Mexico points to ingen-ious practices developed by periurban farmers to use urbanwastewater and groundwater conjunctively for irrigation(Buechler and Devi 2003). However, in water-scarce situa-tions, some industrial wastewater also offers opportunitiesfor livelihood creation through irrigation (Box 2).

Box 2: Conjunctive Use with Poor-Quality Water: Irrigation with MineWater in South Africa

Disposal of mine wastewater is a problem wher-ever there are coal and gold mines, as in SouthAfrica. High concentrations of salt make thewastewater unsuitable for direct discharge intorivers except in periods of high rainfall. The poten-tial for irrigating with mine water in suitable soilsis increasingly viewed favorably as a way of solv-ing the twin problems of wastewater disposal andshortage of irrigation water. How big the oppor-tunity is depends on the availability of suitablesoils nearby, the resultant soil water and salt bal-ance for different cropping systems, the choice ofirrigation management strategies, and the impactof the irrigation drainage on local and regionalwater resources. The approach is inherently con-junctive, because polluted mine water is used tocomplement inputs from rainfall and stream flows.

In a field trial in South Africa during 1997-2000,three center pivots were set up for irrigation withcoal mine wastewater—one in virgin soil(unmined) and two in mine-rehabilitated land.Several crops were successfully irrigated with gyp-siferous mine water on a commercial scale.Excellent yields were obtained for wheat on bothvirgin and rehabilitated land, and also short-sea-son maize grown on virgin land. The yields ofsugar beans were reasonable and higher thanwith dry land cropping. Problems that caused yieldreductions were not related to irrigation with gyp-siferous mine water and were recognized as sur-mountable with experience in the management ofthe system. Research is continuing, using catch-ment-scale computer modeling to assess theimpact of scaling-up on the volume and quality ofsurface water and groundwater.

Source: Olufemi Idowu and Simon Lorentz, Universityof Kwa Zulu Natal, with inputs from IWMI, Africa.

CONJUNCTIVE MANAGEMENT OPPORTUNITIES INTOWNS. Rapid urbanization in many parts of the world havecreated new threats for periurban agriculture. However, con-junctive management of rainfall, surface water, and ground-water creates new opportunities to meet these threats.

CONJUNCTIVE USE WITH SALINE GROUNDWATER.In regions with primary salinity, conjunctive use of surfaceand groundwater presents unique challenges and opportuni-ties. In such places the objective of conjunctive managementis to maintain both water and salt balances. In this situation,system managers require great control and precision in canalwater deliveries to different parts of the command to main-tain an optimal ratio of fresh and saline water for irrigation(Murray Rust and Vander Velde 1992). In many systems, itmakes sense to divide the command areas into surface waterirrigation zones and groundwater irrigation zones, depend-ing on the aquifer characteristics and water quality parame-ters. In others, providing recharge structures within a surfacesystem is often a useful component of a rehabilitation andmodernization package. It is a risky business and requires asound conceptual model of the fate of the salts mobilized, ifit is not to cause more problems than it solves.

Potential Benefits of Reform

Conjunctive water management strategies help reduce evap-oration losses from reservoirs, for their storage can be drawndown more quickly if groundwater can be relied on to meetwater needs later in the year. Conjunctive management canalso add to drought proofing. Surface water storage variesfar more than groundwater storage in response to interyearvariations in precipitation. As a result, groundwater can playa powerful drought-mitigating role when surface andgroundwater are managed and used conjunctively. In the sit-uations identified above, the key benefits of investing in con-junctive use are the following:

• Enhanced yield of past investments in surface water irriga-tion projects through increased irrigated area, improvedwater productivity, and expanded production, employ-ment, and incomes

• Improved sustainability of groundwater irrigation inregions of intensive groundwater use with inadequateavailability of runoff for recharge

• Use of poor-quality water to increase agricultural produc-tion, employment, and incomes

• Enhanced long-term environmental sustainability of irrigat-ed agriculture in salinity dominated environments byimproving salt balances and sustaining the productivity ofirrigated agriculture

Policy and Institutional Issues

CONJUNCTIVE MANAGEMENT REQUIRES A BASIN PERSPECTIVE. Where practiced, conjunctive management isoften confined to the irrigation-system level. Overall gainsfrom conjunctive use can be enhanced by managingresources at the riverbasin level, but this cannot be done untilthe river basin becomes part of the water and land manage-ment unit.

REFORM OF WATER RESOURCES MANAGEMENT INSTITUTIONS. A major obstacle to conjunctive manage-ment is the fragmented structure of governmental institu-tions entrusted with various water management roles.Typically, the main system is managed by irrigation depart-ments, groundwater by groundwater departments, andenergy supply for groundwater pumping by an electricity util-ity. Seldom is there any coordination among these linedepartments. These roles must be coordinated if conjunctivewater management is to succeed.

MONITORING AND INFORMATION SYSTEMS. Improvingmonitoring of groundwater behavior and use patterns in theconjunctive management domain is a priority. Most develop-ing countries have poor monitoring infrastructure. This pre-cludes spatially coordinated use of groundwater and surfacewater that is critical in a saline environment. Geographicdatabases with data on cropping patterns, evapotranspira-tion, groundwater levels, and canal alignments would be avaluable aid to understanding where canals contribute mostseepage to groundwater, where water-intensive perennialcrops are grown, where soil salinity is inherent or due towaterlogging, where soil salinity could be controlled by leach-ing with irrigation water, and where waterlogging is causedby improper surface drainage.

PUBLIC-PRIVATE PARTNERSHIP. In many surface irrigationsystems, public tubewells are used to stop waterlogging andsecondary salinization due to surface irrigation. Experimentswith the Salinity Control and Reclamation project tubewellsin Pakistan and the Satjej-Yamuna Canal in northwest Indiahave shown, however, that private tubewells often do thesame job as well or better. The problem is lack of coordina-tion in private tubewell development. Since surface systemsare managed by government departments and tubewells areoperated by independent farmers, opportunities arise formutually gainful public-private partnerships with better coor-dination and an appropriate policy framework.

REHABILITATION AND HARDWARE IMPROVEMENT.Reshaping the hydraulic infrastructure is critical where ground-water levels are shallow, soils are saline but still favorable, soilsare coarse rather than fine, and canal seepage is abundant.

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Remote sensing can be used to identify such areas. Hardwareimprovement should improve control of water levels in mainand branch canals; automate flow measurement and controlin distributaries, minors, and water courses; and upgrade thedistribution network and field channels.

Lessons Learned

• Conjunctive use of groundwater and surface water oftenoccurs by default. Big opportunities to enhance its gains liein introducing planned conjunctive management throughcoordinated strategies at various levels from the river basindown.

• To achieve effective conjunctive management, plannedinvestments are required in hardware (system moderniza-tion and improved infrastructure), software (improved database), planning and management capacities, and insti-tutional reform.

• Improving main system management is central to better con-junctive management and water level control is critical forbetter main system management. New technologies offerbig opportunities. For instance, expensive communicationinfrastructure can be replaced by low-cost cell phones.

• Conjunctive management in a poor water quality environ-ment presents more difficult, and often unique, technicaland management challenges requiring higher investment.

A key challenge is to create strong incentives for conjunctivemanagement among different stakeholder groups. Typically,perverse incentives through faulty pricing of surface irrigation,electricity for pumping, and investment in groundwater struc-tures undermine gains from conjunctive water management.

Recommendations

• Even where river basin institutions are absent or underde-veloped, planning of conjunctive management seems bestdone within a river basin framework.

• The biggest new opportunities for improving food securityand livelihoods arise in densely populated agriculturalregions that rely on intensive use of groundwater in agricul-ture. In such cases, conjunctive management requires a par-adigm shift. The need and pressures are for augmenting andconcentrating groundwater recharge—through rechargestructures to increase percolation from rainfall and runoff, aswell as from imported water-in pockets of groundwater-intensive use.

• Conjunctive management investments should strike a balance between improving infrastructure and building

conjunctive management capacities—through improvedmonitoring systems, institutional reform, improved man-agement practices, and greater incentive compatibility.

Conclusion

To optimize conjunctive use of water, the best way forward isto concentrate on capacity building of irrigation system man-agers to improve system management and reshape hydraulicinfrastructure of large and small-surface systems. To sustaingroundwater use in tubewell-irrigated areas, enhancingrecharge from precipitation and surface water imports is nec-essary. None of these improvements can be made withoutthe proper institutional and organizational development,including investment in the capacities of local governmentsto lead on participatory groundwater management and inte-grated water resources management.

REFERENCESBlomquist, W., T. Heikkila, and E. Schlager. 2001. “Institutions andConjunctive Water Management among Three Western States.”Natural Resources Journal 41(3): 653-84.

Buechler, S., and G. M. Devi. 2003. “The Impact of WaterConservation and Reuse on the Household Economy” Proceedingsof the Eighth International Conference on Water Conservation andReuse of Wastewater, Mumbai, September 13-14.

Foster, Stephen, Albert Tuinhof, Karin Kemper, Hector Garduno, and Marcella Nanni. 2002. “Groundwater Management Strategies.”GWMATE Briefing Note 3. Sustainable Groundwater Management:Concepts and Tools series. Online at http://www.worldbank.org/gwmate.

IWMI (International Water Management Institute). 2002. “Innovations inGroundwater Recharge.” IWMI-Tata Water Policy Briefing, No. 1.Available online at http://www.iwmi.cgiar.org/waterpolicybriefing/files/wpb01.pdf.

Murray Rust, H., and E. Vander Velde. 1992. “Conjunctive Use ofCanal and Groundwater in Punjab, Pakistan: Management andPolicy Options.” Advancements in IIMI’s Research 1992. A Selectionof papers presentedat the Internal Program Review. Colombo, SriLanka: International Irrigation Management Institute.

Shah, T. 2003. “Decentralized Water Harvesting and GroundwaterRecharge: Can These Save Saurashtra and Kutch from Desiccation?”IWMI-Tata Water Policy Program, Colombo, Sri Lanka.

Shah, T, O. P Singh, and A. Mukherjee. 2004. “GroundwaterIrrigation and South Asian Agriculture: Empirical Analyses from aLarge-Scale Survey of India, Pakistan, Nepal Terai, and Bangladesh.”Paper presented at IWMITata Annual Partners’ Meeting, Anand, India,February 17-19.

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This Note was prepared by Tushar Shah, Principal Researcher at the International Water Management Institute and updated by Salah Darghouth and ArielDinar from the Water For Food Team of the World Bank. It is based on Investment Note 4.3 in the larger volume Shaping the Future of Water forAgriculture: A Sourcebook for Investment in Agricultural Water Management. The Sourcebook documents a range of solutions and good practices fromWorld Bank and worldwide experience, concentrating on investments in policy and institutional reforms in technology and management to improve waterproductivity and farming profitability. You can download a copy of the full report at www.worldbank.org/rural or email ard@worldbank.org.