Estimating evapotranspiration's spatiotemporal variance is critical for regional water resource management and allocation, including irrigation scheduling, drought monitoring, and forecasting. The Surface Energy Balance Algorithm for Land (SEBAL) method can be used to estimate spatio-temporal variations in evapotranspiration (ET) using remote sensing-based variables like Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), surface albedo, transmittance, and surface emissivity. The main aim of the study was to evaluate the actual evapotranspiration for the lower Bhavani basin, Tamil Nadu based on remote sensing methods using Landsat 8 data for the years 2018 to 2020. The actual evapotranspiration was estimated using SEBAL model and its spatial variation was compared over different land covers. The estimated values of daily actual evapotranspiration in the lower Bhavani basin ranged from 0 to 4.72 mm day-1. Thus it is evident that SEBAL model can be used to predict ET with limited ground base hydrological data. The spatially estimated ET values will help in managing the crop water requirement at each stage of crop and irrigation scheduling, which will ensure the efficient use of available water resources.

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The proportion of agricultural water consumption is continuously decreasing due to increased competition for water resources by urban, industrial, and agricultural users. Drip irrigation is more efficient in terms of water and energy utilization. These considerations are critical in view of the ongoing struggle for water resources among various consumers due to water scarcity. Some of the most critical criteria in the effective design and maintenance of drip irrigation systems are the shape and size of the volume of wet soil beneath the emitter. Hence several statistical models were constructed in this research to estimate the dimensions of wetting patterns, which are critical for designing an optimal drip irrigation system. The Nash-Sutcliffe efficiency (NSE), coefficient of correlation (CC), and root mean square error (RMSE) criteria were used to assess the models' performance. The results showed that the Polynomial model was the most accurate for horizontal advance, with 0.94, 0.93, and 1.33 (cm) values for CC, NSE, and RMSE, respectively. For vertical advance, the logarithmic model showed 0.96, 0.96, and 0.72 (cm) values for CC, NSE, and RMSE. Thus, in the absence of a wetting pattern and under identical conditions, these models can be utilized to generate synthetic horizontal and vertical advances data.

The world is attempting to increase water efficiency in all activities, especially in irrigation, which consumes three-fourths of total available water. Concerning  the near future food demand and sustainability issues, views are directed to reduce the usage of water or increase the efficiency of water use. India is a major contributor to the agricultural production and food supply to many countries. Irrigated agriculture is being followed by the many farmers in India which consumes huge amounts of water. Considering the monsoon failure and   increased   water demand, one must find  solutions for retaining  water in an available manner. The focus is on finding major water-consuming crops and irrigation methods under different irrigation environments of Tamil Nadu. Pudukottai, Salem and Erode are the districts of Tamil Nadu state selected as a study area. In each district, blocks, villages and respondents are selected through multi-stage random sampling. This study is entirely based on primary data which is collected using a well-structured interview schedule. The collected data is used to estimate the Physical Water Productivity (PWP) and Economic Water Productivity (EWP). The results show that PWP and EWP are  variable across crops under different irrigation environments. In a tank environment, the alternate drying and wetting method of irrigation in paddy is effective and saves around 39 per cent of water compared to the conventional method  by flooding. For Groundnut crops, drip irrigation is more effective than check basins which are better than the flood irrigation method.   We can conclude that the farmers should follow water-saving irrigation methods/technologies and cultivate   crops that show less demand for water  during the   season when the water is scarce and  turn to   cultivation of  crops like sugarcane and banana in water surplus season.