The irrigation water management planning for cotton crop requires information on optimal thermal regimes i. e. date of sowing, temporal variation of root depth and optimum moisture regimes and sensitiveness of different growth stages to moisture stress. The exponential relationship between cotton yield and seasonal heat unit input was best fitted. The seasonal yield production function was found best fitted in second order polynomial form. The Jenson multiplicative model was found to be the best fitted for describing the effects of both timing and quantities of water consumption on crop yield. The data of benefit-cost ratio showed that under highly deficit and fully water supply conditions, the drip system adoption was not economically desirable. The developed nomographs were found versatile tools for the land and water resources planning. This book therefore, provides a new metric of success for scientists for methodology of water management research and nomograph development techniques for different crops and supplemental to the more traditional cost analysis that most irrigation engineers/planners currently use.