HEMA KUMAR, H.V.SUNITHA, D.V.2018-08-092018-08-092016http://krishikosh.egranth.ac.in/handle/1/5810063801D5460Water is the most vital input in agriculture and its availability is necessary in providing stability to food grain production and self-sufficiency. About 80% of total water resources are being utilized for agriculture. Surface irrigation is widely practiced throughout the world i.e., more than 95 % of world’s irrigated area is under surface irrigation (Anonymous, 2003). India has the highest irrigated area with almost one fifth of the irrigated area in the world. According to statistical year book India 2016, irrigated land in India is about 64.7 M ha of which 55 M ha is irrigated by surface methods of irrigation. The irrigated land in Andhra Pradesh is about 4.2 M ha of which 3.68 M ha is under surface methods of irrigation. All along the coast, Guntur district is predominantly with sandy soils, where deep percolation losses are more thereby having lot of scope to improve irrigation efficiency. In the coastal agriculture, small to medium farmers are dominant group cultivating rice, groundnut and vegetables following check basin and furrow irrigation systems. Under the aforesaid valid and farmers’ felt research needs, the present post graduate research work entitled “Modeling of surface irrigation systems using ‘SURDEV’ in coastal areas of Guntur district” is proposed to fulfil the following major objectives. i) To survey different farmers’ fields for the existing field design of surface irrigation systems in coastal areas of Guntur district. ii) To estimate the overall irrigation efficiency of surface irrigation systems using SURDEV model. iii) To model the design parameters for the improvement of overall irrigation efficiency using SURDEV. A total number of 120 coastal farmers’ fields (60 fields under check basin irrigation system and 60 fields under furrow irrigation system) were surveyed. The major crops grown in the study area are rice, groundnut, pulses in basins; maize and vegetables in furrows. The dominant soil type is sandy. In the present study, software model SURDEV developed by M. Jurriens, was used to determine the existing field efficiencies and to improve the efficiencies of the irrigation systems. The required data for inputting into the model was collected from field survey. With this data from existing basin and furrow irrigation systems were used as input for BASDEV and FURDEV modules respectively for obtaining the application, storage, and distribution efficiencies (%), minimum, maximum and average infiltrated depths (mm), advance and recession times (min), and under-irrigation, over-irrigation lengths and depths. The performance of surface irrigation system proved to be unsatisfactory and so suggestions for improvement were evaluated with BASDEV and FURDEV modules in SURDEV. Also for some fields, cutback and tail water reuse options in FURDEV were used by giving suitable values of cutback ratio and tail water reuse ratio to further increase the efficiencies. To know whether the improvement is statistically significant or not, on theoretical basis, simple statistical analyses were performed. i) Student ‘t-test’ amongst existing and improved efficiencies ii) standard error of mean within a particular group of efficiencies and finally iii) correlation matrix with various input parameters which were changed on hit and miss trials basis were chosen. For rice under basin irrigation system, the overall efficiency was increased from 38.14% to 71.55% using BASDEV module in SURDEV. Similarly, for groundnut and pulses the overall efficiency was increased from 32.48% to 65.15% and 38.49% to 69.15% respectively. For maize under furrow irrigation system, the overall efficiency was increased from 40.8% to 58.32% using FURDEV module in SURDEV. Similarly, for cucumber and for watermelon the overall efficiency was increased from 35.63% to 51.84% and 53.68% to 62.83% respectively. With cutback option in FURDEV module further increase in efficiency was obtained as 9.14% for 20 cucumber fields, 11.85% for 3 maize fields and 12% for 2 watermelon fields under furrow irrigation system. Similarly, with tail water reuse further increase in efficiency was found to be 3% for 6 cucumber fields, 4.8% for 6 maize fields and 2.4% for 1 watermelon field. From the t-test, it was observed that the application and overall efficiencies for all the crops of study area for basin irrigation system and furrow irrigation system showed significant variation in the design exercise at 5% level of significance. It was observed from the standard error calculations that storage efficiency for all crops except groundnut and distribution, overall efficiencies for maize and watermelon crop showed less standard error which means that they are more or less following certain governing pattern and the rest showed standard error equal to and greater than 1 indicating that the efficiencies varied tremendously. From the correlation matrix prepared for the various input parameters (independent variables) and various efficiencies tested in study fields separately for different soils and different irrigation systems, the correlation has not given any uniform pattern for any of soils. In some cases, basin width, cut off time and basin length has shown high correlation and for certain soils like clay loam, sandy loam, loam and silty clay, the sample sizes were very meagre and hence the statistical results outcome could not be worked out. If measures are taken to improve at least 10% in the efficiency by recommending flow rate, cut off time, field dimensions, there will be a saving of water in the tune of 6.129 BCM because of the fact that as per AP water vision, the irrigation water consumption is 61.317 BCM at presenten-USnullThesis