An optimization model has been formulated to maximize the net benefit from a tank command with conjunctive use of
surface water from the tank and ground water from wells and community well in the tank area. The Kannangudi tank in
Pudukkottai district, Tamil Nadu, India has been taken as the case study. Six crops were found in the command area and
are considered for arriving the optimal cropping pattern. The study result shows that, the wells and community well in a
tank command contributes to a sustainable irrigation and apparently maximize the net benefit from that tank command

K. Kuppusamy (7228631)

S. Mohan (580725)

V. Jothiprakash (7228628)

English

Loughborough University Institutional Repository

JOTHIPRAKASH, MOHAN and KUPPUSAMY34730th WEDC International Conference, Vientiane, Lao PDR, 2004PEOPLE-CENTRED APPROACHES TO WATER AND ENVIRONMENTAL SANITATIONCommunity wells for sustainable irrigation in tank commands:  A case studyV. Jothiprakash, S. Mohan and K. Kuppusamy, IndiaIntroductionTamil Nadu state in India irrigates an area of about 0.91 M.ha through 39,200 tanks, which accounts for 17% of all tanks in the country. Apart from surface irrigation, the tank serves as a recharging structure for the underlying aquifer. In most of the tank system, the area near the tank (head reach) receives water for two crops, middle reach receives water for one full crop and tail reach area suffers from water shortage even for a single crop mainly due to the location of sluices at different levels. This situation in the tail reach and part of middle reach, can be managed by constructing a community well (well common to the farmers community in that area) and tapping the recharged ground water for irrigation. In the recent past considerable attention has been paid to the integrated use of surface and ground water in large reservoir, but little work has been done in tank commands. For sustainable agriculture in the tank commands judicious use of water from different sources are essential.Maknoon and Budges (1987) listed out the chronological development of the conjunctive use approach. Mohan and Jothiprakash (2003) listed out different types of conjunc-tive use based on possible combination of land, water and time. Some of the important works reported in conjunctive use modeling are Chandhry (1974), Lakshminarayanan and Rajagopal (1977), Chavez – Moral et al (1987), Kumar and Pathak (1989), Onta and Gupta (1991), Mohan and Arumugam (1992), Peralta et al (1995) Panda et al (1996), Jothiprakash et al (2002), Mohan et al (1998), Emch and Yeh (1998), Belainesh et al (1999). In the present study, a linear programming model has been formulated for arriving optimal cropping pattern in a tank system. The model has been developed consider-ing the conjunctive use of surface water from the tank and ground water from community wells, lying in the aquifer near the tank.An optimization model has been formulated to maximize the net benefit from a tank command with conjunctive use of surface water from the tank and ground water from wells and community well in the tank area. The Kannangudi tank in Pudukkottai district, Tamil Nadu, India has been taken as the case study. Six crops were found in the command area and are considered for arriving the optimal cropping pattern. The study result shows that, the wells and community well in a tank command contributes to a sustainable irrigation and apparently maximize the net benefit from that tank command.Model DevelopmentA linear programming model suggested by Loucks et al. (1981) and Lakshminarayana and Rajagopalan (1977) has been used to allocate the available resources and to derive optimal cropping pattern in the tank command. The objec-tive function and the constraints of the developed model are explained below. The objective function is to maximize the net benefits incurred due to irrigation in the tank command and is given byMax NB = �������������������121112111111tztgwZztztswZzziNiiZzNiziiZzGWCSWCxACAxBwhere, NB- Net benefit in rupees (Rs)Bi- Benefit incurred from crop ‘i’Ci- Cost of cultivation for crop ‘i’ i- No of crops:  i=1,2,…,Nz- Sluice number:z=1,2 &3Axzi- Area of ith crop under sluice ‘z’t - Time period in monthsCsw – Cost of surface water in Rs/Mm3 (Rs 1.5/m3, paid interms of land tax)SWzt - Surface water release (Mm3) to sluice z in period t Cgw – Cost of ground water in Rs/Mm3 (Rs 4.5/m3, paid interms of pumping cost)GWzt- Ground water pumpage during time period ‘t’ in sluice ‘z’The objective function is subjected to the following con-straints.JOTHIPRAKASH, MOHAN and KUPPUSAMY348Surface water storage constraintsThe storage at any month should not exceed the maximum storage (0.65 Mm3) and minimum storage in all months.65.0�tS t=1,2,…, 12  (2)  t=1,2,…,12 (3)005.0�tSwhere, St- Storage in the tank during time period ‘t’.Ground water constraintsThe total ground water pumpage from the wells under each sluice in each month should not exceed the safe yield of the aquifer. These constrains are mathematically expressed as follows:zzt SyGW �   t=1,2,…,12 (4)zzt SyGW �  t=1,2,…,12 (4)where, Syz - Safe yield of aquifer under sluice ‘z’, Water allocation constraintsThe quantity of irrigation water required for each crop in each month should be met with either from the surface water in the tank or from the ground water in the aquifer. These constraints are given as:����Niztgztsziit GWSWAxNIR1��t=1,2,…12     z=1,2&3 (5)���Niztgztsziit GWSWAxNIR1��t=1,2,…12     z= ,2&3 (5)where, NIRit – Net irrigation requirement for the crop ‘i’ during the month ‘t’ηs- efficiency of the surface water irrigation (60%) and  ηg - efficiency of the ground water irrigation (85%)Continuity constraintsThe month to month relation of storage in the tank and re-leases are given by continuity equation and mathematically it is represented asttZzztttt OESWISS ����� ���11t=1,2,…,12 (6)ttZzztttt OESWISS �������11t=1,2,…,12 (6)where , St+1 - Storage in the tank at time t+1It  - Monthly inflow into the tank during time tEt - Evaporation in the tank during time t and Ot  - Surplus from the tank during time tOverflow ConstraintsIf no constraint on overflow is provided then the linear programming model will result in overflow even when the reservoir storage is less than the capacity and hence the overflow constraint developed by Chavez-Morales et al (1987) is used in the present study. The overflow constraint is given by0max1������ ��ttZzzttttOSESWISO t = 1,2,….12  (7) Along with the above constraints the total irrigation area constraints in each season, minimum irrigation area under each crop and non – negativity constraints are also incor-porated.Study areaKannangudi tank in Pudukkottai district in Tamil Nadu, India has been selected as the case study. The basin is situ-ated between 10°40’05’’N latitude and 18°30’45’’ longitude and it has an altitude of 92.650 m. above m.s.l. Kannangudi tank comes under the non-system tank (does not have any feeding canal from a river) (Mohanakrishnan, 1992) and it is situated North of Kannangudi village in Kulathur Taluk of Pudukkottai district and about 35 km from Trichy in Tamil Nadu, India. The catchement covers an area of 23.427 km2. This tank has a capacity of 0.65 Mm3 and serves 116.050 hectares through the three sluices. The area under sluice I, sluice II and sluice III is 30.980 ha, 73.42 ha and 13.235 ha respectively. The location of the study area is shown in Figure 1. High rainfall of 408.6 mm is experienced in North-east monsoon during the months of October, November and December. The annual rainfall in the study area is around 898.06 mm. The ground water is observed in 5 to 25 m depths below ground level. The main crop grown in the command area are Rice-Samba (Aug-Jan), Rice-Thaladi I (Jan-May), Rice-Thaladi II (May-Sep), Groundnut (May-Sep), Cotton (Mar-Aug) and Sugarcane (Annual).Community wellCommunity wells are not new to Tamil Nadu. These wells are found in many villages mostly as drinking water wells rather than an as an irrigation well. This methodology of constructing a community well can be adopted in tank irri-gation also. Usually the community wells are located in the head reach of the tank to harvest the unnoticeable ground water, which is wasted through the aquifer. This water can be conjunctively used with the surface water, when the water from the tank is insufficient to raise the crop. The commu-nity wells are managed by group of farmers. Thus making integrity among the farmers in water sharing. An informal rules and regulations for the operation of the community wells is available with the water users association. In the present study area only one community well is existing in the sluice III and is shown in Figure 1,all other wells are owned by individual farmers.JOTHIPRAKASH, MOHAN and KUPPUSAMY349Data baseThe data required for this study was collected form Public Works Department, Pudukkottai district, Government of Tamil Nadu, India. The field data, regarding the cropping pat-tern, cost of cultivation, net benefit from the each crops were collected through socio-economic survey. Rice, Sugarcane, Cotton and Groundnut are the main crops being cultivated in the study area. Out of the above crops, rice occupies a larger portion of the command area. Monthly net irrigation requirement for each crop grown in the command area was estimated based on the methodology suggested by Doorenbos and Pruitt (1977). The evapotranspiration was estimated using FAO modified Penman method. The estimated NIR is listed in Table 1. The cropping details regarding yield, cost of cultivation, labour and fertilizer requirements for each crop is depicted in Table 2. The mean monthly inflow into the tank for the period of 10 years is shown in Table 3. From the probability studies it is found that 75% depend-able inflow level has mostly zero inflow during most of the months, hence average inflow values are used in deriving the cropping pattern. From the water level fluctuation and specific yield method, it is found that the safe yield of the aquifer in sluice I is 1289 lph. The safe yield under sluice II and sluice III are 1394 and 1332 lph respectively.Results and discussionThe revised simplex method was used to find the optimal cropping pattern, sluice releases, and ground water pumpage with one year as the planning horizon.With above developed model, the optimal cropping pattern was determined for two different scenarios. One is without conjunctive use and other one is with conjunctive use. In the first scenario the model consisted of 66 variables and 105 constraints. The developed model was solved using revised simplex method. The net benefit resulted for this scenario is Rs. 11,57,895.33 ($1=Rs. 52). The optimal allocation of surface water from the tank is shown in Figure 2. The sluice wise release resulted from the model showed that the release in the sluice 2 is more than the other two sluices. For this scenario the area irrigated under sluice 1, sluice 2, and sluice 3 are 39.41ha, 63 ha and 13 ha respectively.In the next scenario the model was solved with conjunctive use of surface water and ground water. This model consisted of 102 variables and 141constraints. This model is also solved using revised simplex method. The net benefit resulted from this scenario is Rs. 26,67,462.49 The increase in the net benefit in this scenario is due to cultivation of sugarcane. Whereas in earlier scenario (without conjunctive use) the sugarcane has not entered into the feasible solution region. The optimal allocation of surface water and ground water for the second scenario is also shown in Figure 2. From Figure 2 it can be seen that the surface water utilization in second case is less and also the total water used is less (sum of surface water and ground water) because of higher efficiency in using Table1. Monthly net irrigation requirements for various crops in the study area  (mm) Rice Month Samba Thaladi-I Thaladi-II Groundnut Cotton Sugarcane Jan -  35 - - - 12 Feb -   53 - - - 49 Mar - 110 - - 59 140 Apr -  90 - - 93 146 May -  50 63 19 121 189 Jun - - 101 40 120 170 Jul - - 86 86 49 174 Aug 73 - 62 78 25 160 Sept 127 - 82 5 - 150 Oct 71 - - - - 106 Nov 48 - - - - 50 Dec 21 - - - - 16 Annual 340 338 394 228 467 1362 Table 2 Net benefit calculation for each crop (Rs/ha) Crop YieldKg/haMarketvalue  Rs/kg Cost of cultivation  Rs/ha NetBenefit Rs/haSamba 3335 8 14330Thaladi-I 4076 5 12350 8030Thaladi-II 4076 5 12350 8030Groundnut 1729 9 9386 6175Cotton 525 47 11115 13560Sugarcane 98800 0.8 24700 54340Table. 3 Monthly inflow into the tank (Mm3)Month MeanJan 0.11Feb 0.04Mar 0.07Apr 0.14May 0.13Jun 0.10Jul 0.18Aug 0.08Sep 0.36Oct 0.10Nov 0.02Dec 0.18JOTHIPRAKASH, MOHAN and KUPPUSAMY350Community well Figure 1.  Location of the study area and community wells      Community well under sluice III          Wells Owned by individual farmersCanal offtaking from sluicesKANNANGUDITANK Sluice I Area = 30.98 haSluice II Area = 73.42 haSluice III Area = 13.325 haTamil Nadu Study areaIndiaFigure 1. Location of the study area and community wellsJOTHIPRAKASH, MOHAN and KUPPUSAMY351Figure 2. Optimal utilisation of surface water and ground water (with and without conjunctive use)May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr MayMonth0.000.010.020.030.040.050.060.070.080.090.10Water released(Mm3 )Surface water release (without conjunctive use)Surface water release (with conjunctive use)Ground water pumpage (with conjunctive use)Figure 2. Optimal utilisation of surface water and ground water (with and without conjunctive use)Figure 3. Optimal cropping pattern resulted from LP model with and without conjunctive use.0510152025303540455055Area under irrigationThaladi-1   Thaladi-2   Samba   Sugarcane   Cotton GroundnutSluice 1 without conjunctive useSluice 2 without conjunctive useSluice 3 without conjunctive useSluice 1 with conjunctive useSluice 2 with conjunctive useSluice 3 with conjunctive sueJOTHIPRAKASH, MOHAN and KUPPUSAMY352the ground water. For this scenario the area irrigated under sluice 1, sluice 2, and sluice 3 are 40.96 ha, 106.84 ha and 19.47 ha respectively. The optimal cropping pattern with conjunctive use and without conjunctive use resulted from the present linear programming model is shown in Figure 3. The sugarcane, which is a cash crop has entered the fea-sible solution with conjunctive use. Thus conjunctive use of surface water and ground water has increased the area under irrigation and also increased the net benefit in the tank com-mands. The model shows that conjunctive use is inevitable for sustainable irrigation in tank commands.ConclusionAn optimization model has been developed to derive opti-mal cropping pattern in a tank command with and without conjunctive use. It was found that the conjunctive use has increased the net benefit by cultivating the cash crop, because of availability of the ground water throughout the year. This ground water available is the recharged water from the tank. The net benefit without conjunctive use is Rs. 11,57,895.33 ($1=Rs. 52) and from the conjunctive use scenario is Rs. 26,67,462.49 Thus it is necessary to practice conjunctive use of surface and ground water under tank commands also for their sustainability.ReferencesBelaineh, G. Peralta, RC; Hughes, TC. (1999) “Simulation / Optimization Modelling for Water Resources Manage-ment”, Journal of Water Resources Planning and Manage-ment, Vol.125, No.3, pp 154 162.Chandhry, MT. (1974) “Optimal conjunctive use model for Indus basin. Journal of the Hydraulics Division, ASCE, Vol. No.5, pp.667 - 687.Chavez-Morales, J., M.A. Marino, and E.A. Holzapfel. (1987), “Planning Model if Irrigation District”. Journal of Irrigation and Drainage Engineering 113, No.4: 549-564.Doorenbos, J., and Pruitt, W.O, (1977) Guidelines for pre-dicting Crop Water Requirements, FAO Irrigation and Drainage Paper No 24. Food and Agricultural Organization of the United Nations, Rome, Italy.Emch, PG and Yeh, WWG. (1998) “Management model for conjunctive use of coastal surface water and ground water”. Journal of Water Resources Planning and Management Vol. 124, No.3, pp.129-139.Jothiprakash V. K.A. Kuppusamy, K. Sasireka and P. Shanmu-ganathan (2002) “Ground water harvesting through com-munity wells for sustainable irrigation in tank commands” Proceedings of the international conference on Water and Waste Water Perspectives of Developing Countries, IIT Delhi, pp597 – 602.Kumar R, and S. K. Pathak (1989) Optimal crop planning for a region in India by conjunctive use of surface and ground water, Water Resources Development, Vol. 5, No2, pp 99-105.Lakshminarayana, V., and S.P. Rajagopalan (1977) Optimal cropping pattern for basin in India, Journal of the Irrigation and Drainage Division, ASCE, 103(IR1), 53 - 70.Loucks, D.P., J.R. Stedinger, and D.A. Haith (1981) Water resources systems planning and analysis, Prentice-Hall, Inc, Englewood Cliffs, New Jersey. Maknoon, R and S.J. Burges, (1987) “Conjunctive Use of Ground and Surface Water”. Management and Opera-tions: 419-424.Mohan S, and N. Arumugam (1992) A stochastic optimiza-tion model for irrigation planning, Proceedings of the International conference on optimization models and their application, National University of Singapore, Singapore, pp 657-663.Mohan S, and V. Jothiprakash (2003) Development of priority based policies for conjunctive use of surface and ground water, Water International, Vol. 28, No2, pp 254-267Mohan S, H. Raman, and K. Nagarajan (1998) Stochastic linear programming model for irrigation planning, Jour-nal of Indian Water Resources Society, Vol. 18. No3. pp 28-34.Onta, PR and Gupta, AD. (1991) “Multistep planning model for conjunctive use of surface and ground water resources”, Journal of Water Resources Planning and Management, Vol.117, No.6, pp: 662 – 678.Panda, S.N., S.D. Khepar, and M.P. Kaushal. (1996) “In-terseasonal Irrigation System Planning for Waterlogged Sodic Soils”. Journal of Irrigation and Drianage Division 122, No.3 : 135-144.Peralata, RC, Cantiller, RRA and Terry, JE (1995), Optimal large scale conjunctive water use planning, Case Study: , Journal of Water Resources Planning and Management, Vol.121, No.6, pp.471 478.Contact addressDr. V. Jothiprakash Senior Lecturer,Dr. K. A. Kuppusamy, ProfessorDepartment of Civil Engineering, National Institute of Tech-nology, Tiruchirappalli, Tamil Nadu 620 015, INDIAvprakash@nitt.eduDr. S.Mohan, Professor, Environmental and Water Resources Engg DivisionDept. of Civil Engineering, Indian Institute of Technology, Madras, Chennai, Tamil Nadu 600 036, INDIAmohan@civil.iitm.ernet.in

Community wells for sustainable irrigation in tank commands: a case study

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Community wells for sustainable irrigation in tank commands: a case study

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