Browsing by Author "Kurien, E K"

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Carbon dynamics in teak planted laterite soils of Kerala
(Academy of Climate Change Education and Research Vellanikkara, 2016) Binsiya, T K; Kurien, E K
Global warming due to increased concentration of greenhouse gases (GHGs) is one of the important concerns of mankind today. The global soils store about 2500 Gt of carbon which is approximately 3.3 times the atmospheric carbon pool (760 Gt) and 4.5 times than that of the biotic pool (560 Gt) . Kerala has a rich forest cover of which 10 per cent is occupied by forest plantations. Among the plantation species, teak occupies the most prominent position both in acceptance and coverage. However, continuous teak rotation affects the quantity and stability. Hence the present study was taken up to assess the changes in carbon fractions and carbon stability under continuous teak rotations in midland laterites of Kerala. Soils were collected to a depth of 1 m with a depth interval of 20 cm in a chronosequence from 16 plantations at Nilambur, Kerala. Basic soil parameters such as pH, electrical conductivity, bulk density, mean weight diameter, texture, available nitrogen, potassium, phosphorus, iron, calcium, copper, manganese, magnesium, zinc and boron content were analyzed using standard protocols. The carbon fractions were assessed with respect to active, slow, passive and total carbon in soil as well as macro and micro aggregates. The study also assessed the rate kinetics, thermal stability and cumulative CO2 efflux of soil carbon decomposition in these soils by batch incubation experiments at different temperatures. The results showed a reduction of soil basic characters below critical levels with continuous teak rotations. In general, the carbon content was found to decrease depth wise with rotation. However, in plantations without felling organic carbon was found distributed equally in all the layers which may be due to the unhindered transportation and translocation of humic materials with time in these plantations. The carbon stocks in the plantations do not have significant difference between the age groups in their carbon storage capacity. This indicated that carbon losses from the teak plantation are readily replenished and the changes may be expected only in the quality of the stored carbon. Macroaggregates were found to store more organic carbon than the microaggregates. The correlation between carbon and aggregate stability was found to decrease with rotation. Plantation that was grown continuously showed a relatively lower proportion of active carbon than slow and passive carbon fractions. This indicated that even though there was a total carbon increase in plantations under continuous growth, the entire carbon may not be in a labile form to support ecosystem services. Thermal stability studies showed that microaggregates provided better protection to organic carbon by a greater complex mechanism compared to macroaggregates. With temperature, there was an increased conversion of active carbon to passive forms and this conversion could lead to higher carbondioxide evolution once the threshold energy levels were attained. Carbon dioxide efflux studies confirmed these results as higher cumulative CO2 evolution was obtained at 40°C than 25°C in all soils. Further, cumulative CO2 evolution from continuous plantation without felling didn‘t get affected with temperature indicating a dynamic equilibrium with atmosphere. The present study concluded that continuous teak rotation destabilizes carbon in soil and shows the potential to revert to a carbon source than sink if not managed sustainably.
Climate change impact on crop water requirement of rice in Thrissur district
(Academy of Climate Change Education and Research, Vellanikkara, 2016) Basil Abraham; Kurien, E K
Rice crop occupies a major position in the agricultural production in Kerala State. Under the present climate change scenarios the climatic parameters are subject to variations and that in turn will affect the water requirement of the crop. A great stress on the irrigation reservoirs and projects for additional water to be released will be effected. It was attempted to generate the climate data for 2030, 2050, 2080 under IPCC emission scenarios RCP.45.The crop water requirement for rice was calculated under the predicted climate for Thrissur district using CROPWAT model. The minimum temperature in the district were found to increase during the future years. The maximum temperature also showed an increasing trend through the future years. The summer months January – March were found to remain as the hot months during the predicted years. The solar radiation was also found to increase. The average annual rain fall for Thrissur district was found to vary as 3139.1, 3089.8 and 3307.6 mm for the future years of 2030, 2050, 2080. The onset of south west monsoon may become early. The summer rains will continue to give a good amount of rain fall through the future years. There will be a reduction in the post monsoon rain fall and a poor distribution of rain fall over the district. The crop evapotranspiration in all the three rice growing seasons of virippu, mundakan and punja was found to increase under the predicted scenario. Crop evapotranspiration was found to increase from 49.99 mm during 2015 to 61.27 mm during 2080 in the first crop season (virippu). During the second and third crop season (mundakan and punja) crop evapotranspiration varied from 56.53 mm to 82.17 mm and 77.06 mm to 83.17 mm respectively. When compared to the year 2050 the irrigation water demand was found to decrease during the year 2080. During the first crop season the irrigation water demand will increase to 319.6 mm in the year 2050 and later during 2080 it was found to decrease to 265.6 mm. There will be a considerable increase in the water requirement during the second crop season during 2050’s and 2080’s when compared with the present day demand. It was also indicated that under RCP 4.5 scenario the water demand to the rice crop during second crop season will be more by 100 mm of water.The crop water use efficiency was found to decrease during future years. An additional amount of 200 billion litres of water will be required for meeting increased water requirement during the second crop season for irrigating rice. The requirement for the third crop season will be high as 750 billion litres.
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; 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)
Erodibility and runoff potential of laterite soils under simulated rainfall conditions
(Department of Irrigation and Drainage Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1999) Sajeena, S; Kurien, E K
Soil erosion is one of the most serious environment degradation problems. However reliable measurement of erosion remains limited and estimates of soil productivity are even rarer. Assessing the extent and seriousness of erosion therefore remains a difficult task Nevertheless, identification and assessment of erosion problems could have an important role in influencing better land use and conservation practices. Rainfall simulators are considered as an effective tool in soil conservation research. Simulators make it possible to produce predetermined storms at any desired time and location. They make the replication of research easier and facilitate the study of storm sequences. Laterite soils are by far the most important soil group occurring in Kerala and cover the largest area. The objective of this study was to estimate the erodibility and runoff potential of laterite soils of three well defined series under simulated rainfall conditions. The rainfall simulator designed and fabricated by Kurien and George (1998) was modified for better performance. The modified simulator could produce rainfall intensities varying from 741 to 23.00 cmlh. Also uniformity of the rainfall produced could be increased to higher values of 88.10 and 91.53 per cent, thus giving a better performance. Intensity of rainfall increased as the 11 pressure of supply water to the simulator increased and a relationship was established between intensity and the supply pressure of water as 1= -87.205 p2 + 108.61 P - 10.786 (R = 0.99) Experiments were also conducted to study soil loss and runoff from three different series of laterite soils, i.e.Mannamkulam series, Naduvattom series and Vellanikkara series. The soil loss and runoff increased with increase in the rainfall intensity for all slopes studied for each series of soil. A general trend of increase In soil loss and runoff with increase in the slope was observed for all the three series of soils. Empirical equations were developed for estimating soil loss (E) and runoff (0) for various intensities of rainfall and land slopes for the three series of soils selected for the study. The equations are: Mannamkulam series E = 1167.797 I + 835.109 S - 21686.07 (R = 0.90) Q = 65.0161 + 16.747 S - 235.923 (R = 0.99) Naduvattom series E = 324.766 I + 112.799 S - 3912.219 (R = 0.97) Q = 74.542 1+19.434 S - 394.323 (R = 0.99) Vellanikkara series E = 115.662 I + 431. 064 S - 11512.284 (R = 0.98) Q = 58.742 I + 26.837 S - 310.019 (R = 0.99) ii1
Ground water resources modelling of a watershed using modflow
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2015) Sajeena, S; Kurien, E K
A study on ‘Ground water resources flow modelling and mapping of a watershed using MODFLOW’, was carried out for Kadalundi river basin of Malappuram District in Kerala. The objectives of the research were 1. to study the aquifer characteristics of the study area, 2. to study the spatial and temporal ground water variations in the study area, 3. to identify the potential ground water zones within the study area using earth resistivity studies and 4. to develop a ground water flow model for the river basin using Visual MODFLOW. Kadalundi river basin has a drainage area of 1122 km 2 with a main stream length of 130 km, originating from the Western Ghats at the western boundary of Silent Valley. River flows through the district of Malappuram and downstream reach of the river falls into Arabian Sea. In order to evaluate the aquifer characteristics of the study area, spatial and temporal variations of ground water level of dug wells and bores wells were analyzed separately. Monthly water table data from 16 bore wells and 14 dug wells during the period from 2008 to 2013 were used for the study. From the p re and post monsoon water table and piezometric water level variations and from the water table and piezometric water level hydrograph studies, it was observed that the water table and piezometric level fluctuation in low land, mid land and high land area were correlated with rainfall except at some locations like Kottakkal, Marakkara and Tanur. Hydraulic continuity studies were carried out with the help of statistical analysis and it indicated that the hydraulic continuity of ground water and surface water exists between aquifers of dug wells and bore wells in major part of study area. Areas like Thirurangadi, Kottakkal and Some part of Perinthalmanna, variation of piezometric water level was poorly correlated with rainfall, which indicated that hydraulic continuity does not exist in that areas and these areas are suitable for deep bore wells.Vertical Electrical Sounding (VES) method was carried out using Signal Stacking Resistivity Meter (MODEL-SSR-MP-ATS) at 22 locations. The apparent resistivity values obtained from the resistivity meter were interpreted with the help of ‘IPI2WIN’ software to obtain the layer parameters. The sounding curves are of A,H,K,Q,HK and KH types reulting in 3 to 4 layer sequence. The curves are prominently of H, Q, K and A type indicating the presence of three layer and combination of curves like HK and KH indicating the four sub surface layers. Most parts of the study area are dominated by H type curve which indicates the presence of good quantity groundwater. Visual MODFLOW software version 2.8.1 developed by Waterloo Hydrogeologic Inc. was used for the flow modelling of the study area. The conceptual model for the study area was developed based on the base map of Kadalundi river basin, topo sheet of the area, well logs at 30 sites and the data obtained from the geophysical studies conducted in the study area. Discretization was done by dividing it into 62 rows and 136 columns with a grid spacing of 500 m x 500 m throughout the area and the cells outside the boundary of the study area were made as inactive. Monthly pumping rate from 35 pumping wells and monthly water level data from thirty head observation wells of Ground Water Department (GWD), Government of Kerala were used as well inputs of Visual MODFLOW. Hydrogeological parameters such as hydraulic conductivity, specific storage, specific yield, porosity and initial heads and boundary conditions of the model domain including constant head, rivers, drains, recharge and evapotranspiration were used as input of Visual MODFLOW. After uploading input parameters, the model was run for steady state and transient state subsequently. Model was developed and calibrated using four years data from 2008 to 2011 and a reasonably good agreement was obtained between computed and observed water levels. After calibration, the model was validated for t w o years data of 2012 and 2013. The root mean square error (RMSE) for almost all the wells during validation were reasonably low and within acceptable limits except a few wellsvery close to the river which are most likely to be influenced by the interflow of river. After the model development and validation, it was used to predict the flow head for the next 15 years assuming five per cent yearly decrease in recharge and also to predict the ground water condition by increasing the pumping rate by 10, 25 and 50 per cent of pumping rate of the validation period (2013). From the modelling studies, it can be concluded that the Kadalundi river basin will remain safe for next five years from the point of future ground water development and subsequently the water table may reach the bed rock. This necessitates artificial ground water recharge techniques to supplement the recharge of rainfall to the ground water.
Impact of convection over the equatorial through on Indian summer monsoon activity
(Academy of Climate Change Education and Research, Vellanikkara, 2015) Gopika, S; Kurien, E K
The existence or nonexistence of break and active cycle of rainfall over the Indian subcontinent during the mid-monsoon months of July and August decides the success and failure of Indian monsoon rainfall. Effect of active or break cycle, convective systems and convection over the equatorial trough (ET) on Indian summer monsoon rainfall (ISMR) were studied. An increased number of convective systems in the west Pacific showed high negative correlation with rainfall over equatorial trough regions. During active monsoon years, cyclones are focused between 10° - 25° N and 110° - 140° E whereas the cyclones were widely distributed during the break monsoon years. The co-occurrence of active or break spells and convective activity have considerable influence on ISMR. During an active spell, enhanced convection was observed over North Indian Ocean (NIO) while during break spell it was over ET regions. Strong, widespread and short duration cyclonic activity over North West Pacific (NWP) resulted in a break spell in ISMR. The relative influence of El-Niño Southern oscillation and Indian Ocean Dipole (IOD) events on ISMR have been further studied for the period 1950-2010. In order to look into the role of El-Niño on the monsoon, the SST data over five regions (REG-I to REG-IV) were studied. SSTs in the central Pacific (Niño 3.4; REG- II) and eastern Pacific (Niño 3; REG- III) regions were more correlated with ISMR during the observation period. Decadal analysis showed that the temperature of central Pacific region indicated rapid cooling in the recent decades and increased the temperature gradient between western and eastern Pacific Ocean. This cooling in the central Pacific could create La-Niña type conditions. During El-Niño (La-Niña) years, the weakened (strengthened) Walker circulation influence the summer monsoon rainfall over the Indian subcontinent. The newly created Walker circulation index is a promising tool to examine the strengthening (weakening) of the Walker circulation to predict the Indian summer monsoon in future research.
Impact of fertigation and drip system layout on performance of chilli(Capsicum annum)
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2012) Nadiya Nesthad; Kurien, E K
The study “Impact of fertigation and drip system layout on performance of Chilli (Capsicum annum)” was taken up with the objective of determining the effect of fertigation, drip system layout and different levels of irrigation for chilli under plastic mulch. Different fertigation equipments like ventury injector, dosmatic fertigation unit and fertilizer tank were tested to study the hydraulic performance of the system. Ventury injector for fertilizer application was found to have high suction rate in comparison with dosmatic fertigation unit. The suction rate and motive flow rate was found to vary directly with respect to the pressure drop between the inlet and outlet of the fertigation equipment. Ventury injector can be used only if the discharge rate is above 14.6 L/min. Dosmatic fertigatrion unit and fertilizer tank can be used if the discharge rate is above 1.1 L/min and 6.6 L/min. The moisture distribution pattern under different drip field layout was observed. The moisture content near to the plant base was found to be high and decreases as the distance from the emitters increased. The effect of different irrigation levels and drip system layout under plastic mulch on the performance of Chilli (Capsicum annum), Ujwala variety was also studied. The number of branches, stem girth and yield showed significant difference between the treatments. The yield showed significant difference with different levels of irrigation and drip system layout. Maximum yield of 18.32 t/ha was observed for the treatment T5. The treatments T6 (17.952 t/ha) was on par with the treatment T5. The benefit cost ratio for treatment T5, 85 per cent of the irrigation requirement with one lateral for each row of crop was 3.8 and treatment T6, 85 per cent of the irrigation requirement with one lateral in between two rows of crop was 3.9. Even though the yield for the treatment T5 was high, the benefit cost ratio stands high for treatment T6. The high value of benefit cost ratio for treatment T6 was due to the reduction in the quantity of material for drip irrigation system
Soil erosion studies under simulated rainfall conditions in a lateritic terrain
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2014) Praveena, K K; Kurien, E K
Soil erosion IS a complex phenomenon involving the detachment and transport of soil particles, storage and runoff of rainwater and infiltration. Soil erosion depends on several factors such as climate, soil type, topography, cropping and land management practices, the antecedent conditions and the size of the area under consideration. The present study was carried out in the lateritic terrain of KCAET campus, Tavanur, Malappuram District. This study was aimed at developing a rainfall simulator and studying the performance of the developed rainfall simulator, the effect of rainfall on soil loss, the effect of rainfall on runoff and developing a soil erosion model. A rainfall simulator was fabricated to study the erosion processes. Rainbird 12115118 Van Pop up sprinkler heads were used as the drop formers. The simulator evaluated for its performance. The soil was reddish brown and belonged to the textural class of sandy loam. It belonged to the Naduvattom series. The experimental set up consisted of three units viz., the runoff plot, the rainfall simulator and the runoff-sediment collection unit. Twelve runoff plots with twelve different slopes of 1.5, 2.0, 2.6, 3.0, 3.2, 4.0, 5.0, 6.0, 9.0, 10, 12 and 13 per cent in different locations, each plot with a size of2 x 1.5 m were prepared. The fabricated rainfall simulator could produce rainfall intensities varying from 8.16 to 8.80 ern/h. The uniformity of rainfall varied from 89.01 to 92.70 per cent and the average drop size varied from 1.5 to 2.8 mm. A relationship between supply pressure and intensity of rainfall as well as intensity and uniformity of rainfall was developed. Studies were conducted on soil loss and runoff at different land slopes under simulated rainfall conditions. The soil loss and runoff was found to increase with increase in rainfall intensity and land slopes and there were no much variations on runoff and soil loss at 6 to 10 per cent land slopes. A linear multiple regression analysis and 3D surface plot analysis was used to incorporate slope and rainfall intensities into a single prediction equation of soil loss and runoff using SPSS software and MATLAB package. The linear equations developed by the regression analysis are as follows: Q = 38.9451 - 11.606 S - 126.391 E = 124.356 1 - 0.807 S -951.420 (R2 = 0.649) (R 2 = 0.307) The quadratic equations developed by the 3D surface plot analysis are as follows: Q = 130.8 - 28.72 S + 48.12 1 + 2.11 S2 - 1.544 S 1 E = - 647.4 - 49.261 + 86.94 S - 0.3206 12 +6.296 S I As the variants explained were satisfactory enough to explain the runoff and soil loss, it may be concluded that the causative factors namely slope and intensity are bearing directive impact on soil erosion. A canonical analysis was worked out to determine the effect on runoff and soil loss by the vector of parameters u ing slope and intensity. Canonical R was computed and the same was 0.82034 and it is significant at 1 per cent level. Hence it may be concluded that the vector of process 'including slope and intensity as parameters together navigates the ultimate impact namely runoff and soil loss.
Trends in India summer monsoon distribution over the western ghats
(Academy of Climate Change Education and Research Vellanikkara, 2016) Abhijit Asokan; Kurien, E K
The Western Ghats with its strategic position plays a great role in channelling the summer monsoon rain into the mainland. The natural ecosystems and human livelihoods of this region are highly dependent on the Indian Summer Monsoon rainfall and even the slightest change can trigger a change in these systems. The global climate changing scenario is having its toll in the monsoonal system over this region. The extreme events in the region have been analysed for trends using Mann Kendall method and the return periods of the one day maximum rainfall has been modelled using Generalized Extreme Value (GEV) theory. The mean annual monsoonal rainfall over the region is 1616.15 mm and the standard deviation is 242.966.It was observed that the mean annual monsoonal rainfall varied from 231.4mm in grid 117 to 3416 mm in grid 253. The one day maximum rainfall extracted from the 32 constituent grids for the entire period showed a variation from 118.63 mm in 1981 to 316.63 mm in 2005. The temporal variation in one day maximum rainfall for the time series had a significant trend. The values were seen to increase steadily and a profound increase was observed in the recent decades. When the One day maximum rainfall was analysed for different latitudes, two latitudes (14°N and 21°N) had significant positive trends in One Day Maximum Rainfall in the whole region. Out of the 32 grids, 7 grids (186, 359, 394, 428, 429, 497 and 498) showed a significant rising trend in one day maximum rainfall. It was also observed that during the recent years, the occurrence of One day maximum Rainfall has shifted to the far end of the season. The number of grids getting heavy, very heavy and extreme rainfall events was found to have increased during the later years of the study. No significant trend in the instances of occurrence of heavy rainfall over the years was observed. But a significant trend was observed in the occurrences of rainfall events of very heavy and extreme magnitudes. When Split period analysis of the contribution of moderate and high intensity rainfalls was carried out, it was observed that the share of high intensity rainfalls had increased and a decrease was observed in the share of moderate events over the years. The return period analysis of the one day maximum rainfall events was done and it was observed that the 2 year, 5 year, 10 year, 25 year, 50 year and 100 year return levels of rainfall as 186.2mm, 224.3 mm, 250.2 mm, 283.8 mm, 309.3 mm and 335.1 mm for the complete region. The return levels for the two year return period were seen to be over 100 mm for the grids of 184 (118mm), 219 (114.9mm), 253 (145.8mm), 285 (104.5mm), 357 (147.6 mm), 392 (144.2mm), 427 (129.9mm) and 462 (122.4mm). A significant rising trend in the extreme events of summer monsoon rainfall over the Western Ghats was observed. This calls for better planning in all areas of livelihoods and management strategies to contain the disasters of a changing climate.