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1989 - 198911990 - 19933
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Subject: Land and Water Management Engineering × Author: KAU × End date: 2006 × Type: Thesis × Thesis Type: M.Sc ×
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Now showing 1 - 4 of 4
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    ThesisItemOpen Access
    Infilitration and water advance studies under surage flow furrow irrigation
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology,Thavanur, 1993) Rema, K P; KAU; Xaviour Jacob, K
    Furrow irrigation necessitates the wetting of only a part of the surface of land, thus reducing evaporation losses, lessening the puddling of heavy soils and making it possible to cultivate the soil sooner after irrigation. Surge irrigation in furrows possesses the capability to increase irrigation efficiency, by ensuring water saving, better uniformity and reduced tail water losses in different soil and site conditions. To assess the suitability of the system for use in the sandy loam soils of Tavanur region, and to obtain suitable management parameters for surging in the area, a study was conducted at the Instructional Farm of KCAET, Tavanur. Continues flow was compared with surge flow of cycle ratios ½, 1/3 and 2/3 with cycle times 6.9 and 7.5 minutes for discharges of 1.3, 1.7, and 2.1 lps. Data of advance time, depth of flow and inflow-outflow measurements were collected during field irrigation runs. Surge flow in all cases advanced faster compared to continuous flow. For cycle ratio ½ the reduction in advance time ranged as 14.59, 22.8 and 14.77 per cent for the three discharge rates. In the case of cycle ratio 1/3, the reduction was 37.6, 41.94 and 38.01 per cent respectively, whereas for cycle ratio 2/3, the reduction was 34.29, 32.83 and 22.73 per cent respectively. Infiltration variability was lesser under surge flow and the values of infiltrated volume and infiltrated depth at various sections along the furrow length was lesser. Surging with cycle ratio 1/3 and a discharge of 1.3 lps showed the least variability in infiltrated depth and the greatest uniformity of application. Infiltration rate was found to decrease significantly along the length of the furrow and between consecutive surges. The lowest intake rate was obtained for surge flow of cycle ratio 1/3. Surging with cycle ratio 1/3, and a discharge of 1.3 lps required only 1.11 m3 of water to complete the advance. This was the least value compared to continuous flow and other surge flow cases. Analysis of variance of the volume required to complete the advance indicated significant difference between flow types at 5 per cent and 1 per cent levels. The variation between discharges was also significant at 5 per cent and 1 per cent levels. Thus surge flow proved advantageous compared to continuous flow in the sandy loam soils of Tavanur region and surging with cycle ratio 1/3 and a discharge of 1.3 lps was chosen as the best out of the selected treatments for the study.
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    ThesisItemOpen Access
    Design, fabrication and testing of an equipment to measure deep percolation
    (Department of Land and water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1990) Jolly Kutty, Eapen; KAU; George, T P
    Because of the semi - aquatic nature, the water requirement of rice is 2 - 3 times greater than other crops. The measurement or prediction of percolation losses in field situation is of great practical significance for efficient irrigation and also for the determination of the nutrient losses. A precise knowledge of water requirement of crop attains importance for increasing production. The present investigation was taken up to design, fabricate and test an equipment to collect deep percolation water, quantify it and to assess the nutrient losses in the percolation water. The study was undertaken in ‘Mundakan’ season and the variety was ‘Triveni’. The location was the Instructional Farm of KCAET, Tavanur. The main source of irrigation water was filter point tubewell. Estimations of evaporation, transpiration and percolation were made on the basis of measurements using evaporimeter, evapotranspirimeter and field hook gauge. Vertical percolation was assessed using percolation – meter which was designed and fabricated for this study. Lateral percolation was obtained by subtracting vertical percolation from total percolation. The study revealed that the total water requirement was 1270.25 mm. The percentages of water lost by evaporation, transpiration, and total percolation are 13.69, 31.0 and 55.3. The water which is lost by vertical and lateral percolation are 59.4 and 40.6 per cent of the total percolation respectively. There was a gradual increase in the rate of evaporation during the initial stage. Then it decreased up to 65 days and then again increased up to the final stage. Rate of transpiration remained almost constant up to 10 days and then the rate slowly increased as the crop grew. The rate increased up to the booting stage. There was a gradual decrease in the rate of transpiration in the final stage. The rate of total percolation remained almost constant during the crop period. More than 50 per cent of the applied water is lost through percolation. During the initial stage, vertical percolation rate was higher than in the subsequent days. After 10 days, the vertical percolation rate remained almost constant. The rate of lateral percolation was constant during the crop period except in the sixth week after transplanting. The samples of percolation water were collected and the NPK losses due to deep percolation were analysed by the standard methods. The maximum percolation losses of applied NPK occurred on the first day of application and there was only traces from the fourth day onwards. Nitrogen and potassium losses were higher than the loss of phosphorus which was negligible. The NPK losses due to deep percolation is not much when compared to the run off losses. This may be due to the fact that the NPK content in the solution gets fixed in the soil as it percolates down through the soil. So the water that goes beyond the root zone will contain only very little NPK. The equipment fabricated for the measurement of deep percolation losses worked satisfactorily. Knowledge of water requirement of rice will greatly help in the efficient utilisation of available water.
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    ThesisItemOpen Access
    Determination of constants in uniform flow formula for small discharges in open channels
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1990) Parvathy, S; KAU; George, T P
    An attempt was made to find out the constants in the general uniform flow formula for small discharges less than 10 1/s in cement lined and earthen channels. These constants were compared with the constants in the well known and widely used uniform flow formulae such as Manning’s and Chezy’s equation and checked their validity for small channels. Experiments were conducted for different discharges varying from 1 to 9 1/s and for different slopes of 1/2000, 1/3000, 1/4000 and 1/5000 in cement lined and earthen channels. With the help of a computer, analysis was made to establish a relationship between velocity v, hydraulic radius R and slope S. The expirical equation obtained are In cement lined channel V = 9.199 R0.7591 S0.1103 i.e. V = 1/0.1087 R0.7591 S0.1103 In earthen channel V = 47.2286 R0.844 S0.307 i.e. V = 1/0.0212 R0.844 S0.307 From the comparison of actual velocity with velocity obtained by using Manning’s equation, it was found that Manning’s equation was not applicable to small channels having discharges less than 10 1/s. In both the channels, actual velocity was roughly two times greater than the Manning’s velocity. The average ratio of actual and computed velocity using the best fit equations and the coefficient of determinations in the two cases were near unity. Hence the best fit equations obtained in the study are recommended for the design of small channels. Manning fixed the value of exponent of S as 0.5 based on some theoretical assumptions. So it was decided to find the value of n and the exponent of R in both the channels by fixing the value of exponent of S as 0.5. The equations obtained are In cement lined channel V = 1/0.00428 R0.7827 S0.5 In earthen channel V = 1/0.00408 R0.8696 S0.5 These equations were good but their reliability were less than that of the previous equations.Since Manning’s equation is an university accepted form, comparison was made between the recommended n values and the n values obtained in the study by fixing the value of exponent of R and S as 0.67 and 0.5 respectively. The equations obtained are In cement lined channel V = 1/0.00609 R0.67 S0.5 In earthen channel V = 1/0.00778 R0.67 S0.5 Though the reliability of these equations were comparatively less than the earlier cases, it gave reasonably good results. So these equations are also recommended for the design of small channels with different n values for cement lined and earthen channels. Chezy’s constant C was determined from the best fit equations by fixing the value of exponent of R and S as 0.5. The equations obtained in two channels are In cement lined channel V = 94.91√RS In earthen channel V = 74.771√RS These C values obtained are recommended for the design of small channels in Chezy’s equation than the C values obtained from Manning’s and Kutter’s equations using Manning’s recommended n values. Soil in which earthen channel was constructed was classified based on texture. Since the soil was sandy loam, the best fit equation obtained in earthen channel is applicable only for sandy loam soil.
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    ThesisItemOpen Access
    Hydraulics of tile drains in peat and muck soils
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1989) Raju, T D; KAU; George, T P
    Agricultural drainage is the removal of excess water, known as free water or gravitational water, from the surface or below the surface of farm land so as to create a favourable soil conditions for crop growth. The process of removing the excess water from land surface is called surface drainage. The excess water saturates the pore space of the soil, the process of its removal by downward flow through the soil is known as subsurface drainage or internal drainage. In the case of kari land of Kuttanad the field level is below the surrounding waterbodies, there is always an upward movement of water from the subsoil to the surface. The upward movement of water from the subsoil brings along with it harmful byproducts of decomposition of organic matter which when come into contact with roots of plant adversely affect the gorwth and yield. With regard to the experiment on finding the suitable envelope material for subsurface drainage system in peat and muck soils revealed that the river sand (big size) was adequate in terms of filtration quality and hydraulic conductivity. Thus river sand (big size) could be considered as a suitable envelope material for subsurface drainage experiments. In the second experiment the performance of tile drains viz. PVC and baked clay pipe were assessed. From the comparison of head loss fraction and entrance resistance between PVC and baked clay pipe showed that the performance of baked clay pipe was good compared to PVC pipe. Considering the performance and economical reasons related to cost of baked clay pipe and its local availability, the use of the same as tile drains in peat and muck soils was confirmed. A close study of weekly values of EC of irrigation and subsurface drainage water revealed that a quantity of 124.80 kg of salts/ha/cm drop of drained water, could be washed off from the experimental area. From the observations on the growth and yield attributing characters it could be concluded that subsurface drainage was effective upto 30 m spacing. However, further studies are to be carried out for finding out a higher spacing. Economic analysis related to subsurface drainage using tile drains and envelop material (river sand) for a 100 ha area revealed that this project is economically and financially viable.