Browsing by Author "Xavier K Jacob"

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Effect of different shadings on the environmental parameters
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2006) Bindu, P K; Xavier K Jacob
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; Xavier K Jacob
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.
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; Xavier K Jacob
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.
Simulation of the effect of land and vegetation management on runoff and sediment yield from a small watershed- a case Study
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology,Thavanur, 2000) Vinod Kumar, P R; Xavier K Jacob
Conservation of soil by sound measures forms one of the fundamental premises towards a sustained future. The management of land and vegetation has profound influence in conservation programme. To simulate the effect of land and vegetation management measures on runoff and sediment yield from a waterhed, a study was conducted at Development Unit – IX of Attapadi region, in Palghat district. The relationship between effective rainfall and sediment mobilized due to rain storm was established as; ES = 28.57 ER0.9385., where ES is the effective sediment mobilized in T/km2 and ER is the effective rainfall in cm. The Universal Soil Loss Equation (USLE) was applied on perstorm basis to estimate the soil erosion. The Modified – USLE (R) factor was used to represent the erosivity factor in the soil loss estimation. The topographic factor (LS) was computed using the USLE and Revised – USLE methods. This particular parameter computed with the USLE was more than that of the RUSLE. The amount of soil erosion predicted with the USLE were more than that of the RUSLE due to greater LS factor associated with the USLE method. However both methods provided an ‘r2’ value of 0.9724. The WEPP – model was applied to simulate the runoff and soil erosion processes during individual rainstorm events. The model provided reliable simulation of the erosion process, but the runoff values were under – predicted for all the simulated events. The hillslopes cultivated with tuber crops gave maximum erosion per unit area during the simulation. The reason could be assumed as the absence of sufficient ground and canopy cover in this areas, which possessed a loosened surface after harvesting. The lands left as barren after tree felling also had increased rates of erosion during the simulation, which could be due to the lack of vegetative protection. While the paddy field had lesser rates of erosion owing to the flatness of land and vegetation cover. The other areas yielded reduced rates of erosion due to good canopy cover as well as surface cover provided by closely growing vegetation.
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; Xavier K Jacob
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.