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Theses

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1993 - 19965
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Subject: Land and Water Management Engineering × End date: 1996 × Type: Thesis × Thesis Type: M.Tech. ×
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Now showing 1 - 5 of 5
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    ThesisItemOpen Access
    Effect of land use on water yield from small agricultural watersheds of western ghats
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1993) Abdul Hakkim, V M; KAU; Xaviour Jacob, K
    Effect of deforestation and other land use changes brought about by human activities of hydrologic cycle continues to be of great concern. A study was conducted to assess the effect of land use on water yield from small agricultural watersheds of Western Ghats of Kerala. Four small watersheds planted with cashew, rubber, coffee and tea were selected for the study. To get information regarding rainfall, temperature, humidity and daily evaporation; raingauges, thermometers and USWB class A Pan evaporimeters were installed in each watershed. The runoff which is of specific concern was measured using stage level recorders along with weirs and flumes. Infiltration measurements were done using double cylinder infiltrometers. Soil samples were collected from each watershed and were analysed for grain size distribution, soil pH and organic carbon content. Different geomorphological characteristics of the watersheds were also worked out. Analysis of rainfall and runoff data indicated that nearly 50 per cent of the total rain fall leaves these watersheds as runoff except in the case of rubber watershed. The infiltration studies indicated that all these watersheds have high infiltration rates even after saturation, thereby absorbing even the most intense storms of the study period. From the hydrograph analysis of these watersheds it was observed that the hydrographs attain a sharp peak immediately as the rainfall and there is a baseflow which is folowing through the 3 watersheds, except in the case of rubber watershed. The rubber watershed is very small and lies adjacent to the Kuttiadi reservoir. The interflow from the rubber watershed was observed to join the reservoir avoiding the measuring channel. From the soil profile analysis of Western Ghat region it was observed that there is an impermeable clay layer lying below the laterite having an average thickness of 3.5 m located at 7 to 10.5 m below the ground surface. The results of the study leads to the conclusion that the infiltrated rain water meets the impermeable layer and there it flows laterally through the soil. This lateral interflow reaches the valley portion of the watersheds where it saturates the soil. This saturated area acts like an impervious layer producing 100 per cent surface runoff and it is responsible for the sharp peak of hydrographs. Runoff is generated from these source areas and Hortanian overland flow is a rare phenomenon in these watersheds. Thus from the study it was concluded that land use has no significant effect on water yield from the selected small agricultural watersheds of Western Ghats of Kerala.
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    ThesisItemOpen Access
    Simulation studies on different design parameters of spurs (Groynes)
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1995) Roy, Mathew; KAU; Xavior Jacob, K
    The Use of spurs as river training measure has proved to be an effective means of protecting river bank and their design requires indepth knowledge about its parameters related to the solution of a specific river training problem. To analyse various design parameters of spurs, a simulation study was conducted at KERI,Peechi. Characteristics such as flow pattern, velocity distribution and scour pattern was analysed for different spur lengths 25 cm, 35 cm, 45 cm and 55 cm, spur angles 900, 1000, 1100 and 1200, spur spacings 2L, 3L, 4L and 5L and for discharge rates 14.14 1ps, 28.28 1 ps and 42.42 1 ps. Single spur and multiple spur scheme were tested on rigid as well as mobile bed condition. The analysis of the obtained flow pattern, velocity distribution and scour pattern reveals that the specified design parameters have a significant effect on flow diversion, length of bank protected, maximum scour depth at the spur nose, percentage increase in velocity at opposite bank etc. The analysis of the present study also led to conclusion that L/B ratio of 0.19, spure angle of 900 was the best combination for single spur study and the same with a spacing of 5L was most effective for multiple spur scheme.
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    ThesisItemOpen Access
    Design fabrication and testing of a rainfall simulator
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1993) Kurien, E K; KAU; George, T P
    Rainfall simulators are considered as effective aids in soil conservation research. Simulators make it possible to produce predetermined storms at any desired time and location. A rainfall simulator suitable for soil erosion studies was designed and fabricated at KCAET Tavanur. The developed simulator was tested for its performance. Erosion studies on laterite soil was conducted using the developed simulator. The rainfall simulator designed and fabricated was of an oscillating, tubing tip type. The crop former unit consisted of 112 numbers of 18 gauge hypodermic needles fitted on a 1.8 cm GI pipe network. The speed of oscillation was 8 oscillations per minute. The drop former unit was supported at a height of 3 cm above ground level. Intensity of rainfall was varied by changing the pressure of water supply to the simulator. The simulator was tested for intensity, droplet size and uniforimity of application of the rainfall produced. The intensity of rainfall was related to the pressure of water supply as 1 = 6.0386 – 31.9152 P + 177.30 P2 The drop size obtained was 2.31 mm for an intensity of 4.77 cm/hr and the corresponding drop sizes for intensities of 5.60, 6.73, 6.99 and 8.80 cm/hr were 2.20, 2.18, 1.05 and 0.80 m respectively. Christiansen’s uniformity coefficients calculated for intensities ranging from 4.77 to 8.80 cm/hr varied from 82 to 88 per cent. Experiments were also conduced to study soil loss and runoff from laterite soil. The soil loss increased with the intensity of rainfall for all the slopes studied. Maximum soil loss of 1464 kg/ha/hr occurred from a slope 20 per cent at a rainfall intensity of 8.80 cm/hr. A general trend of increase in soil loss with slope was observed. At an intensity of 8.80 cm/hr the soil loss from 5 per cent slope was 940.2 kg/ha/hr whereas the soil loss from 20 per cent slope was 1464 kg/ha/hr for the same intensity. At 5.60 cm/hr intensity of rainfall the runoff from a slope of 5 per cent was 325.33 m3 /ha/hr whereas the runoff was 432 m3 /ha/hr at 6.73 cm/hr intensity for the same slope. Empirical equations were developed for estimating soil erosion and runoff for various intensities of rainfall and land slopes. The equations are : 1. E = -982.384 + 2834.63 S + 225.239 1 (R = 0.94) 2. Q = -216.174 + 1104.65 S + 79.375 1 (R = 0.92)
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    ThesisItemOpen Access
    Effect of different tillage methods on percolation loss in rice fields
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1993) Mini, P K; KAU; George, T P
    Water loss by deep percolation constitutes a major part of the total water loss from the rice fields. Puddling is widely carried out in rice field to create favourable soil condition for the growth of rice plant and to reduce the loss of water through percolation. An experiment was conducted in sandy loam soil to determine the effect of different tillage methods on percolation loss of water and to evaluate their effect on grain yield. The treatments choosen for the study were puddling with power tiller, puddling with tractor cage wheel, puddling with animal drawn puddler (TNAU helical blade type), compaction using roller and puddling with country plough along with planking (control). The experiment was laid out in randomized block design with five replications. Seedlings of short duration rice variety ‘triveni’ were used for transplanting. The daily water loss from the experimental plots was measured using field hook guage. The water loss through percolation was obtained by subtracting the evapotranspiration from the total water requirement. The mean water requirement was highest in the plots puddle with country plough (1609.3mm) and was lowest in the plots puddled with tractor cage wheel (1510.3mm). The percolated water constitute 62 per cent and 64.34 per cent of the total water requirements in the plots puddled with tractor cage wheel and country plough respectively. The lowest mean percolation of 936.12 mm was recorded in the plots puddle with tractor cage wheel. It was followed by puddling with power tiller (949.92 mm), compaction using roller (966.02mm), puddling with animal drawn puddler (1025.02mm) and puddling with country plough (1035.12mm). However, the treatments did not differ significantly regarding the loss of water through percolation. The percentage variation of the percolated water for the different treatments over the control was maximum (17.66 per cent) during the vegetative phase. The variation from the control decreased during the latter two stages and was minimum during the ripening stage (3.89 per cent). The plots puddle with tractor cage wheel recorded the highest yield (11.26 kg/plot) compared to other treatments. The water use efficiency varied from 15.68 kg/ha-cm (puddling with country plough) to 18.64 kg/ha-cm (puddling with tractor cage wheel). The yield and water use efficiency also did not differ significantly among the treatments. The reason for the insignificant among the treatments regarding the loss of water through percolation, yield and water use efficiency could be attributed to the sandy loam nature of the soil since the response of rice plant to various tillage methods depends up on soil texture. It is known that the surface soil aggregates play a major role in controlling the infiltration rate of soil. Since the soil in the experimental field consists of 10 per cent gravel, 65 per cent sand, 12.5 per cent silt and 12.5 per cent clay, the amount of finer particles available for clogging of pores and surface seal development are less in these type of soil, which might be the reason for the treatments not showing any significant variation in the water loss through percolation. From the study undertaken, it was concluded that different tillage methods have no effect in light textured soil in controlling the loss of water through percolation.
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    ThesisItemOpen Access
    Monthly water balance model for lateritic hill slope- a case study
    (Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1996) Beena, Thomas; KAU; Noble, Abraham
    The groundwater balance of K. C. A. E .T. Campus, Tavanur, Kerala has been studied and a deterministic model has been developed for the prediction of depth to water table in this hill slope based on Darcy’s equation. The input data required are the precipitation, evapotranspiration, specific yield, initial water table, elevation of the points under consideration and the distance between the points. The weekly precipitation and evapotranspiration were calculated and from this the recharge to groundwater was estimated. The groundwater recharge was taking place only during the southwest monsoon season. The change in storage divided by the hydraulic gradient for a period without rainfall i.e., from 01 December 1994 to 16 February 1995 were determined. Using these values and other inputs in the model, the depth to water table for a period from 26 May 1994 to 25 May 1995 were estimated from the model. These values were compared with the observed values for the same period. It was found that the estimated values give a reasonable estimate of the depth to water table in the study area. This model can be used to predict the changes expecting in the water level in a particular region. The model has several areas of application in the fields of groundwater resource development and irrigation. The infiltration characteristics of the selected area was evaluated and observed that the infiltration rate was increasing towards the higher elevation. The model was simulated for different percentages of effective rainfall and found that, at 50 per cent it accounts as groundwater recharge and the rest as surface runoff.