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Open Access
Spatial mapping of flood prone areas and risk assessment of Chalakudy river basin using HEC-HMS and HEC-RAS models
(Department of Irrigation and Drainage Engineering, Kelappaji college of Agricultural Engineering and Technology,Tavanur, 2021-10-17) Gudidha Gopi.; Rema, K P.
Floods are one among the most devastating natural disasters that affects life on the globe. For the planning and design of water resources projects in the preferred area, planners and engineers usually require reliable estimates of flood magnitude and frequency. Kerala state in the Indian sub continent received a catastrophic flood in the year 2018. The present study attempts to model the flood flows and map the flood prone areas of a river basin in Kerala. The Chalakudy river basin, one of the worst-affected river basins due to heavy rains and floods was selected for the present study. This is the fifth largest river in Kerala. The basin is predominant with agricultural land and falls under the humid tropical zone, where water resources planning and management is necessary for irrigation scheduling, flood control and design of various engineering structures. In order to address the above issues, an attempt was made to calibrate and validate HEC-HMS model for simulating the flood hydrograph for the Chalakudy river basin. Flood frequency analysis was carried out to estimate the flood peak values using frequency distributions in HEC-SSP software. The results were compared with the estimated flood peak values for different return periods obtained from the HEC-HMS model. Hydraulic routing was done in HEC-RAS model and the flood inundation maps were prepared. The cadastral level risk areas were identified based on water surface profiles of velocity and depth of flood extent and its characteristics. Food vulnerability maps based on land use patterns were developed in order to identify the severely affected land uses. The HEC-HMS model for the basin was developed using SCS-UH, SCSCN, Recession and Muskingum methods to find out the loss rate, runoff transformation and routing of flood respectively. Statistical performance indices of the model, Nash-Sutcliffe efficiency (NSE) and Coefficient of correlation (R²) values were obtained above 0.7, Error in Peak Flow (%) and Error in Volume (%) were figured below 20% and Root Mean Square Error-Standard Deviation Ratio (RSR) was acquired as 0.5 and below. These values indicated that HEC-HMS model simulation performed well in both calibration and validation. The frequency discharge values calculated using Log Pearson type-III distribution indicated a high degree of similarity to the HEC-HMS generated values with an R 2 value of 0.862. The results of the Log Normal and Gumbel distributions are significantly lower than those of the HEC-HMS model values. The assessment of the vulnerability due to the flooding was made with regard to the land use pattern and cadastral level risk map of Chalakudy river basin was developed for different return periods. Kadukutty Panchayat located in the downstream of Chalakudy river basin was found to be the maximum flood inundated area for 10 year return period ( 557 ha) and for 200 year return period (681 ha). Manjapra Panchayat located in upstream was found to be the least flood inundated area for 10 year return period (6 ha) and for 200 year return period (9 ha). Annamanada, Kadukutty, Melur and Pariyaram panchayats were under high risk areas, with depths greater than 20 m. Ayyampuzha, Chalakudy, Mala, Kuzhur, Parakkadavu and Puthenvelikara panchayats were under medium risk areas with depths varying from 10 to 20 m. Athirappilly, Manjapra and Karukutty panchayats were under low risk areas with depths less than 10 m. The flood vulnerability maps were generated by intersecting the flood plain land use map with the flooded area polygons. Paddy land near to the river banks was found to be the highest inundated by different return period floods, followed by forest and other vegetation, barren land and other land use classes
Open Access
Assessment of greenhouse cultivation problems in Kerala
(Department of Soil and Water Conservation Engineering, KCAET, Tavanur, 2021) Deepthi S, Nair; KAU; Jinu, A
Greenhouses are framed or inflated structure covered with transparent or translucent material large enough to grow crops under partial or fully controlled environmental conditions to get optimum growth and productivity. Greenhouse have many advantages and some limitations also. Due to this farmer are abandoning this cultivation method citing crop failures after the initial phase. Thus, a survey was conducted to explore the reasons of failures of greenhouse farmers in Kerala covering all fourteen districts. Major problem faced by farmers was crop failure due to ageing of cladding material. So that fungal growth and dust deposit over the cladding material reduce the light transmission to the greenhouse which affect its microclimate and growth and yield parameters. To prove this, a field experiment was conducted during the period from April to June 2021 in the instructional farm of KCAET, Tavanur, Kerala. CO-1(Amaranthus green variety) was planted inside both cleaned greenhouse and uncleaned greenhouse (greenhouse without cleaned cladding material) and compared the microclimate and performance of Amaranthus in both conditions. Mean monthly values of light intensity and temperature were higher inside the cleaned greenhouse than the uncleaned one while relative humidity was higher inside the old greenhouse. Thus, crop growth parameters like plant height, number of leaves, number of branches and average yield per plant were higher inside the cleaned greenhouse than the old one whereas the inter nodal length of the plant was higher inside the old greenhouse. From this experiment, it was clear that the aging of cladding material has much influence on crop performance under the greenhouse. Other major problems faced by farmers were a decrease in soil fertility, Fungal/Insect attack inside the greenhouse, high maintenance cost 101 and structural problems of greenhouse, no demand and marketing facility of greenhouse products, etc. From the statistical analysis of survey details, it was clear that farmers are not satisfied with the greenhouse.
Open Access
Effect of Bakkikayam regulator on groundwater using geophysical techniques and visual modflow
(Department of Soil and Water Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2020) Smegha, N C; Sajeena, S
A study on ‘Effect of Bakkikayam Regulator on groundwater using Geophysical Techniques and Visual MODFLOW’ was conducted at the ayacut areas of Bakkikayam regulaor, situated across the Kadalundi River at Pandikasala, Vengara, Malappuram district. The objectives of the research work were to study the aquifer characteristics of the area using earth resistivity studies, to assess the groundwater flow variation due to the presence of Bakkikayam Regulator, to develop ground water resource map of the study area using Visual MODFLOW and to identify the potential ground water zones of the study area. In order to analyze the aquifer characteristics of the study area, Vertical Electrical Sounding (VES) survey was carried out using Signal Stacking Resistivity Meter (MODEL-SSR-MP-ATS at 18 locations and were interpreted using IPI2WIN software. The sounding curve obtained from the interpretation of resistivity studies revealed that most part of the study area showed H and HK type curve indicating the presence of good to moderate quality ground water. From the VES studies it could be concluded that, top soil of the study area is either laterite soil or hydromorphic soil of thickness 0.75 to 4 m, followed by laterites with varying hardness to a depth of 4 m to 17 m. Lithomargic clay of thickness less than 2 m is seen below the laterites in some places. These layers are overlying weathered rock of 2 to 14 m thickness followed by hard rock with or without fractures. Major aquifer formations in the study area are identified as laterite, clay and weathered rock. Effect of bakkikayam regulator on ground water variation was analyzed based on pre and post monsoon water table data. The ground water level during pre and post monsoon from dug wells located in upstream and downstream side of the Bakkikayam regulator were observed and the difference between pre and post monsoon water table (water table fluctuations) were noted .It was observed that the water table fluctuation in the wells located in downstream side ranged from 5.41 to 5.62 m. Visual MODFLOW software version 2.8.1 was used for the groundwater modeling of the study area. A base map was prepared and imported in to the model as bmp format. The conceptual model for the study area was developed using base map, well logs and the data collected by conducting geophysical survey of the study area and the study area was discretized by dividing into 50 rows and 50 columns with a grid spacing of 530 m x 520 m. By comparing the water table contour map obtained from the validated model before and after the implementation of Bakkikayam Regulator, it could be seen that the light blue color is changed to green color, indicating that there was a decline of 3 to 4 m water table in the downstream side of the regulator. The validated model was used to predict the water table contour map of the study area for the next five years by increasing the recharge rate 10, 20 and 30 percent of the recharge rate of the validated period (2019). An increase in water table of 2m was observed during the predicted period due to 20% increase of ground water recharge rate. Beyond that there was no significant change in water table and remained more or less constant. This is due to the reason that topography of the downstream area of the Bakkikayam regulator especially parts of Nannambra and Tirurangadi Panchayaths comes under low land. The ground water flow from this area is towards the river and from where water drains into Arabian Sea. This necessitates some obstructions to check the flow of river or any other water conservation measures at downstream side. From the velocity vector map obtained using the Visual MODFLOW model, it was observed that the flow direction and magnitude were maximum in two water bodies locally named ‘Morya Kappu’ and ‘Venchali Kappu’, which can be identified as high ground water potential area. At present these water bodies and their drainage channels of around 10,000 m are filled with sediment deposits. Hence it is recommended that the deepening of two water bodies upto 3 m and their drainage channels upto 1.6 m, is essential to solve the problems encountered for paddy cultivation in Nannambra Panchayath to a large extent.
Open Access
Water availability and climatic water balance for a selected cropped area
(Department of Irrigation and Drainage Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2018) Venkata Sai, K; KAU; Asha Joseph
Rainfall is the main source available for water. The knowledge of the rainfall analysis is crucial for crop planning in a region and designing of water conservation structures. The changes in rainfall, its distribution, probability and trends would influence the spatial and temporal distribution of runoff, soil moisture and groundwater reserves. Crop production in an area has a direct relation with the amount and distribution of rainfall. So correct evaluation of water availability period is an important pre-requisite for crop planning. Climatic water balance is widely used for determining the water surplus, water deficit and water availability period for agricultural planning. Hence in the present research work, the rainfall data of Pattambi was analysed to study the variability, trends and probability of rainfall. A weekly climatic water balance was also assessed to determine the surplus/deficit of rainwater. The rainfall variability analysis showed that the mean annual rainfall of Pattambi region was found 2377.96 mm with a CV of 19.29 % which indicated that the rainfall is highly stable in the region. The South-West monsoon season contributed the highest (74.09 %) amount of rainfall. June and July were the months recorded the highest percentage of rainfall of 25.39 % and 24.06 % respectively. Weekly rainfall variability showed that rainfall was stable during 21st to 45th SMWs as the CV ranges from 90 % to 110 % only. The trend analysis of annual, seasonal and monthly rainfall according to Mann-Kendall test revealed that there was a rising and falling trends. But there was no significant trend observed at 5 % level of significance except in summer season. The Sen’s slope estimator revealed that a rising trend was observed in summer season whereas falling trend was observed in annual, South-West and North-East monsoon season and no trend was observed at winter season. The rainfall probability at different levels of exceedance were found by fitting “Incomplete gamma distribution” using Weather Cock software. The weekly rainfall probability at 75 % level of exceedance varied from 10.3 to 72.6 mm during the weeks 21st to 46th. The highest monthly rainfall at 75 % exceedance occurred during June (471.1 mm) and lowest during January (3.1 mm). The highest seasonal rainfall at 75 % exceedance occurred during South-West monsoon (1466.4 mm) and lowest during winter season (10.8 mm). The annual rainfall at 75 % level of exceedance was found to be 2051.6 mm. Weibull distribution was identified as the best fit for weekly rainfall distribution in the region. The total ETc demand of rice, banana and vegetable crops at 50 % probability levels of ETo was estimated as 469.162 mm, 1124.81 mm and 267.92 mm whereas the rainwater availability at 75 % probability level was 933.85 mm, 1107.53 mm and 59.18 mm respectively. It was observed that there was a surplus of 464.688 mm for rice, deficit of 17.28 mm for banana and deficit of 208.74 mm for vegetable crop. The climatic water balance indicated that water surplus (SUR) and water deficit (DEF) components are significant. The total climatic water surplus and deficit in the region was estimated as 1985.54 mm and 155.08 mm. The Moisture Adequacy Index (MAI) of the region indicated that the most of the weeks were of in good potential for growing crops. The determination of water availability period revealed that 1,4,5,8, 9, 11 and 50th SMWs were in water deficit whereas the remaining weeks were in water surplus.
Open Access
Soil erosion risk assessment in Kunthippuzha sub-watershed using remote sensing and gis
(Department of Soil and Water Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology Tavanur, 2018) Shaheemath Suhara, K K; KAU; Abdul Hakkim, V M
This study mainly focused to identify the erosion prone areas in Kunthippuzha sub-basin using RUSLE as well as MMF model. The effect of spatial and temporal variations of land use-land cover on soil erosion was analysed with the help of NDVI values. The estimation was performed for the year 2000 and 2013. The mean soil erosion estimated for the year 2000 was 18.30 and 20.58 t/ha/y respectively by MMF as well as by RUSLE model. Similarly in the year 2013, it was 32.78 and 35.10 t/ha/y respectively. To find the erosion prone areas in the sub-watershed factorial scoring method was chosen, in which pixel based scoring was done based on mean soil erosion value obtained under each layers of landuse, rainfall, slope and topographic raster. From the study based on the RUSLE model, 0.15% of the area experienced very slight erosion. 40.70% of the area was with slight erosion, 28.76% area was under moderate erosion, 22.61% of the area was under severe range and 6.15% area was under very severe range. According to MMF model, the areal extent observed under slight, moderate, severe and very severe risk categories was 39.02%, 36.94%, 14.92%, 7.50% respectively. NDVI values corresponding to land use were identified, in which negative NDVI values correspond to water pixels whereas higher NDVI values represents the thick vegetation. From the analysis of the temporal variation in land use over the NDVI, it was observed that NDVI value decreased at the points where density of the canopy decreased. The spatial variation of soil erosion varies pixel to pixel according to the landuse pattern. Highest soil erosion risk was observed under built-up plus barren land. Sediment Delivery Ratio (SDR) was calculated for the entire sub- watershed, which shows that most of the eroded sediments get deposited at intermediate location before reaching the outlet. The SDR calculation enhances the importance of adopting GIS technology in soil erosion assessment.
Open Access
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; KAU; 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.
Open Access
Development of a filter system for roof water harvesting
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2014) Shijila, Erikottil; KAU; Sathian, K K
This thesis work was undertaken to study the performance of modified mesh filter under rainfall. The mesh filter was modified with two other filters such as sand and charcoal filter and their combination study was conducted on artificial rainwater and evaluated the quality of filtered water. The two filters are fabricated with naturally available material such as above 1 mm size coarse sand and small pieces of burned coconut shell. These materials are freely available from surroundings and each material was filled in each PVC pipes of 25 cm length. From the first study four buildings are selected in the campus have different impurity levels that because of rain fall events, purposes or constructed material. It was found that there are small variations in the quality of harvested water but after filtration all results are same because filter was not depends on the roofing material and impurity level. The quality parameter like pH of the rainwater harvested after the filtration with mesh filter for all roofs met the USEPA secondary drinking water standard range of 6.5-8.5. The electrical conductivity, turbidity and suspended solids are also met the drinking water standards by WHO and the calculated average filter efficiency of mesh filter was 81.3 %. From the filter combination study the quality parameter such as pH, electrical conductivity, turbidity and suspended .,olids also examined through water quality analyzer of collected samples. As per the BIS 10500 of 2004 and WHO all the results are in the permissible range. The BOD test result was ranging from 44 to 92 mg/l and compared to inflow the filtered water has drastic reduction in the values. From the coliform test it was cleared that there were no colifirms (011 OOml) in the filtered water after 24 hour incubation period where as in inflow water coliforms were detected. It was found that there is a marked reductio'. .n the concentration of impurities, The reduction in im urities ranges from 84 to 86 % and the charcoal tilter has highest filtration rate of 9.42 m3/minlm2 compared to others. The results clearly. revealed that combined filters remove the impurities in a more efficient manner than of the mesh filter developed earlier. There is only minor difference between the both filters. The results clearly revealed that combined filters remove the impurities in a mo: e efficient manner than of the mesh filter developed earler. There is only minor difference between the both filters.
Open Access
Design and evaluation of a horizontal filter unit for ground water recharge through abandoned tube well
(Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2016) Jomol, T Joseph; KAU; Rema, K P
The groundwater table is declining at an alarming rate and it is essential to replenish the dried out aquifers by adopting proper artificial recharge methods. Field experiment on the design and evaluation of a horizontal filter unit for groundwater recharge through abandoned tube well was conducted in the research field of Nodal Water Technology Centre, College of Horticulture, Vellanikkara. The specific objectives of the study were to design and develop a horizontal filter unit with alternate filter media for treating storm water runoff, and to evaluate the developed filter for hydraulic and pollutant removal efficiencies. Suitability of the tube well for recharging and availability of adequate amount of source water were analysed in the primary stages of study. The peak runoff expected from the area was computed and compared with the carrying capacity of the existing conveyance channel. Thus the existing channel was modified and a masonry structure with a filter unit for treating runoff and a recharging section was constructed. The filter unit had five compartments filled with Gravel, Sand, Charcoal, Synthetic fibre and Coir fibre combinations as treatments, T1: Gravel, Sand, Coir fibre, Gravel; T2: Gravel, Sand, Synthetic fibre, Gravel; T3: Gravel, Charcoal, Sand and Gravel. Three sets of length variation in three different media combinations were selected as factors, F1: 80 cm, 80 cm, 80 cm, 80 cm; F2: 80 cm, 100 cm, 60 cm, 80 cm; F3: 80 cm, 60 cm, 100 cm, 80 cm Inflow and outflow water quality was analysed for evaluating filter hydraulic and pollutant removal efficiencies in simulated and actual runoff conditions. Treatment T1F1 was better in pH normalising efficiency, T1F2 removed Nitrate and Sulphates effectively, T1F3 was better in Total hardness and Calcium removal efficiency, T2F1 performed well for Magnesium and Chloride removal efficiencies. Treatments T2F2 and T3F3 were effective for EC, TDS, Salinity, TSS, Turbidity, Acidity, Fluoride, Alkalinity, Iron removal and Hydraulic efficiencies. 135 The Gravel (80 cm), Charcoal (100 cm), Sand (60 cm) and Gravel (80 cm) combination was selected as best filter media combination and it was installed in the field for recharging. With an average annual rainfall of 2795 mm in the study area, a runoff depth of 1118 mm can be expected. Accordingly a runoff volume of 2.3 million litres of water can be diverted from the study area to the recharge well annually. Comparison of this enormous benefit from the artificial recharge structure with the cost incurred is indicating the promising future of the artificial recharge schemes. If the abandoned open wells and tube wells in Kerala are utilised as recharge wells, a large quantity of water can be recharged annually and it will improve the groundwater potential of the state for future benefits.
Open Access
Studies on the effect of alternate growing systems and irrigation schedules for soilless culture of salad cucumber
(Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2015) Sabeena, Shahul; KAU; Rema, K P
Field study on the effect of alternate growing systems and irrigation schedules for soilless culture of salad cucumber under drip irrigation was conducted inside the naturally ventilated polyhouse in the research plot of Precision Farming Development Centre, in the Instructional Farm of KCAET, Tavanur, during November 2013 to March 2014. In this study coirpith was the media used. The crop water requirement of salad cucumber was determined using CROPWAT model. The data on micro climate inside the polyhouse were periodically recorded on daily basis. The physico chemical and engineering properties of coirpith were studied. The experiment was laid out in a two factor completely randomized block design. The plot was divided into three rectangular sections with three treatments each replicated thrice. The treatments were F1T1 (Black poly bag with daily irrigation), F1T2 (Black poly bag with alternate day irrigation), F1T3 (Black poly bag with irrigation once in 3 days), F2T1 (Lay flat grow bags with daily irrigation), F2T2 (Lay flat grow bags with alternate day irrigation), and F2T3 (Lay flat grow bags with irrigation once in 3 days). Fertigation in coir pith include both macro and micro nutrients applied as water soluble fertilizers from two tanks (tank A and tank B) through fertigation system with venturi. Data about vegetative parameters for each treatment were observed during different stages of crop growth. The results on the effect of alternate growing systems used, irrigation frequency and their combined effect on crop growth and yield parameters were statistically analyzed. Analyzing the effect of alternate growing systems, it was found that vertical type growbag filled with coirpith showed better performance than lay flat type growbag. In case of irrigation interval, crops under once in three days irrigation showed better performance at the initial stage (winter season). But during mid-season (summer season) alternate day irrigation resulted in better growth and yield than once in three days irrigation. The highest yield was for F1T2 (7.56 kg/plant) followed by F1T1 (6.34 kg/plant). Irrigation interval significantly affected irrigation water use efficiency (IWUE). The highest IWUE was for F1T3 (2590 kg/ ha.mm) and lowest was for F2T1 (446.14 kg/ ha.mm). Even though crops under alternate day irrigation were identified with remarkable yield, once in three days irrigation can be suggested in the areas experiencing water shortage. The results of this experiment showed that it is possible to obtain satisfactory yields of hybrid cucumber Hilton variety grown under polyhouse conditions in coirpith filled vertical growbags. The study also revealed that crops with once in three days irrigation at initial stages followed by alternate day irrigation during mid-stage and late stage in vertical type growbag resulted in better performance. Using inert growing media like coirpith demands full fertigation with all macro and micro nutrients for good FUE.

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