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A water balance model applicable to intermittent irrigation practice in rice ®elds was developed. The model inputs consist of climatic data and soil parameters. The model is formulated to simulate various processes such as evapotranspiration, deep percolation, surface runo and depth of irrigation water to be applied on a daily as well as a seasonal basis. It also simulates daily ponding depth in the ®eld. Both saturated and unsaturated water¯ow concepts were incorporated into the model to predict deep percolation loss during wet and dry periods of the ®eld. The model was validated using data collected from ®eld experiments. The details of model development and validation are outlined in this paper.

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Field experiment for pea (Pisum sativum L.) (PB-89) crop was conducted during rabi 2016-17 and 2017-18 at Punjab Agricultural University, Ludhiana. The objective of the experiment was to study the impact of different irrigation methods, viz. drip, furrow and flood irrigation on crop growth parameters and yield of the crop. Better growth parameters, viz. plant height, leaf area index, dry weight of root and shoot and the chlorophyll content were recorded under drip irrigation. Plant height and leaf area index had a positive correlation to yield of the crop. Weight of grain was also positively correlated with the grain yield. There was increase in yields in 2017-18. Yield was found significantly higher under drip irrigation treatments.

A mathematical model is developed for the estimation of groundwater recharge through surface drains for both free flow as well as detained flow conditions. The Dupuit-Forchheimmer equation is solved using the Crank-Nicolson central finite difference scheme, to obtain the mound height matrix. The Gaussian elimination method was used to solve the matrix, to obtain the mound height at different radial distances across the drain. Various hydrogeological parameters like hydraulic conductivity, specific yield, etc. are determined by field investigations. Surface runoff available due to a particular rainfall event is correlated with recharge rate available in the drain. The model gives volume of water recharged for various rainfall events under different antecedent moisture conditions for both free flow and detained flow conditions. The value of recharge rate computed by using the model for a particular depth of flow in the drain is matched with the observed values. The model is more sensitive to change in the value of specific yield than hydraulic conductivity.