Abstract:
The world is facing severe challenges in meeting the rapidly growing demand for water resources. In addition,
irrigation water which is the largest use of water in most developing countries and arid and semi arid regions, will likely
have to be diverted increasingly to meet the needs of the households in urban areas and industry sectors whilst remaining a
prime engine of agricultural growth. A Linear Programming (LP) model has been developed to allocate the land and water
resources to different crop activities for maximizing the net return. Application of the model for the irrigation water
management revealed that in winter, 89.4% of available channel water was utilized, out of which 55.9% and 18.5% were
allocated for wheat and barley, respectively .The remaining 25.6% channel water was allocated for cotton and
watermelon. Since there were enough channel water supplies in this season, only 10.6% of available groundwater was
utilized. In the absence of constraint on conjunctive use, there would have been no groundwater exploitation, and 100% of
the channel water, which is much cheaper than groundwater, could have been utilized, if required. During summer season,
the entire quantities of water available in channel as well as groundwater resources were utilized. In this season, as there
was limited channel water supply, considerable part of the irrigation requirement was met from available groundwater.
Based on the LP analysis, out of total available channel water, 43.2% was allocated to cotton cropping, which was most
profitable as compared to all other crop activities, followed by 38.3%, 9.5% and 9% to crop activities including
watermelon, barely and wheat, respectively. Out of total available groundwater, 65.8% was allocated to cotton whose
irrigation water need was high and the remaining 34.2% was shared by wheat, barley and watermelon cropping activities.
The model predicts that in the case of changes in irrigation water supply, it will be economic to change the cropping
pattern.
Machine summary:
A Linear Programming (LP) model has been developed to allocate the land and water resources to different crop activities for maximizing the net return.
The activities suggested in chapter 18 include the development of interactive databases, forecasting models, economic planning models and methods for water management and planning, and the optimization of water resources allocation under physical and socio- economic constraints (Labadie et al.
Most of the studies of optimization on irrigation water management adopt simplified or linear objective functions to maximize the net benefits while selecting an optimum cropping pattern.
The river basin has been acknowledged to be the appropriate unit of analysis to address these challenges facing water resources management; and modeling at this scale can provide essential information for policy makers in their decisions on allocation of resources (Knapp, 1996).
The linear programming technique has been widely used to formulate the conjunctive use to arrive at an optimal allocation of surface and groundwater, to maximize the benefits within the framework of given constraints and proposed cropping pattern (Khepar and Chaturvedi, 2006).
Water requirements of crops in the region (m3/ha) Month/ Crop Wheat Barley Cotton Watermelon Jan. 0 0 0 0 Feb. 0 30 0 0 Mar. 340 360 0 0 Apr. 1250 1320 70 0 May 1860 1790 850 870 Jun. 1410 740 1670 1430 Jul. 0 0 2620 2220 Aug. 0 0 2340 1810 Sep. 0 0 1500 260 Oct. 0 0 340 0 Nov. 670 670 0 0 Dec. 0 0 0 0 Total 5530 4910 9390 6590 Table 2.