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Open Access
Modelling the hydrology of watershed by using HEC-HMS
(Department of Irrigation and Drainage Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2016) Makkena, Jyothi; KAU; Vishnu, B
A hydrological model is a commonly used tool to estimate the hydrological response of a watershed to precipitation. Hydrologic Modeling System (HEC-HMS) is a physically based semi-distributed hydrologic modelling software developed by the Hydrologic Engineering Center (HEC) of the U.S. Army Corps of Engineers. It is designed to simulate the complete hydrologic processes of dendritic watershed systems under various widely varying geographic conditions.
Open Access
Investigations on energy conversion of waste coconut water through an Up-flow Anaerobic Hybrid Bioreactor
(Department of Farm Power, Machinery and Energy, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2016) Dayanand, Kumbar; KAU; Shaji, James P
Many Agro-industries discharges considerable amount of wastewater to water bodies. Anaerobic digestion of organic effluents from agro-industries has a great importance in pollution abatement as well for renewable energy production. Waste coconut water (WCW) is a medium strength waste water for which high rate anaerobic treatment is an affordable technology. This technology offers simultaneous production of energy in the form of biogas along with pollution control. Conventional biogas plants are slow in operation with long Hydraulic Retention Times (HRTs) in the order of 35 to 55 days, necessitating very large digester volumes. Hence, anaerobic treatment of WCW is technically and economically feasible only through high rate bioreactors, where we can reduce the HRTs in the range of 6 to 8 days. Hence, an investigation was taken up to study the performance of a high rate bioreactor viz. Up-flow Anaerobic Hybrid Bioreactor (UAHBR) for biomethanation of WCW. It was revealed that the WCW had a low pH along with high Bio-chemical Oxygen Demand (BOD) and Total Solids (TS). The semi-continuous digestion WCW was carried out in a lab scale floating gas holder digester. The digester was operated at different HRTs of 35, 30 and 25 day and performance evaluated. During all HRT there was a profound effect of pH over the working of the digester. The maximum daily biogas production and biogas productivity were 21.9 L and 3.5 L.L-1 during 30-day HRT. The TS reduction had the maximum value of 51.94 at 35-day HRT. The performance of the digester deteriorated at 25 day HRT and the minimum reduction was only 1.38 %. The system showed signs of failure. Existing full scale UAHBR was operated at different HRTs of 16.67 and 15 day and performance evaluated. The reactor was stable in operation throughout the period of operation and revealed high organic reduction with biogas production. The maximum specific biogas production and biogas productivity were 354.31 Lkg1TSadded and 13.50 L.L-1 during 15-day HRT. The TS reduction was in the range of 79.35 and 81.40 during the period of 15-day HRT.Experimental UAHBR was fabricated and performance evaluated at different HRTs of 15, 12, 10, 8 and 6 day. Reactor was stable in operation during 15, 12, 10, 8 and 6 day HRTs and exhibited high process efficiency characterised by good organic reduction and biogas production. The performance was slightly deteriorated with 8 and 6-day HRT. The maximum daily biogas production and volumetric biogas production were 114 L and 877 L.m-3 for 6-day HRT. The maximum specific biogas production and biogas productivity were 225.73 L.kg-1TSadded and 8.7 L.L-1 during 15-day HRT.
Unknown
Development of seedling uprooting unit for system of rice intensification
(Department of Farm Power Machinery and Energy, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2016) Sreerag, P M; KAU; Shivaji, K P
The present study was conducted to develop a seedling uprooting machine for System of Rice Intensification (SRI). System of Rice Intensification is a method developed in Madagascar in the early 1980’s, where, it has been shown that yields can be enhanced by suitably modifying certain management practices such as controlled supply of water, planting of younger seedlings and providing wider spacing. In this method 12 to 15 days old root washed seedlings are transplanted on the well puddled field. Only one younger seedling is transplanted per hill with row to row and hill to hill spacing of 25 cm. The preparation of seedlings for this method involves uprooting from nursery and washing the roots. This is done manually and no mechanical device for uprooting seedlings is available at present. In this circumstance, there is a need for the mechanization in the uprooting, washing and feeding the seedling to root washed transplanter. On this ground a seedling uprooting unit for system of rice intensification was developed and field tested. The seedling uprooting unit was consists of four major components namely bed cutting tool, conveyor unit, main frame and power unit. In order to cut the required thickness of soil bed, cutting tool was developed and fabricated with MS flat sheet of 2mm thickness. It consists of a rectangular base plate (25×30 cm) placed horizontally beneath the cutting blade. The cut seedling beds were conveyed through a slatted belt type conveyor having two adjacent roller chains inter linked with MS flat linkages giving overall belt width of 25 cm and 155 cm belt length. In order to drive the conveyor belt, a power unit from the existing vertical conveyor reaper was chosen. It consisted of 4 hp gasoline engine. According to the geometry of power unit a suitable frame was fabricated using MS angles (3×3 cm) to attach the cutting and conveying unit. The developed seedling uprooting unit was tested in the field to optimize the speed of operation and angle of cutting. Three levels of angle of blade viz., 20, 30 and 40 degrees and three levels of engine speed viz., 1000, 2000 and 3000 rpm were selected for the study. The thickness of bed, time of operation, wheel slip and plant damage were tested with respect to the above selected cutting angles and engine speeds. From the field observations it was found that cutting angle of 30° with engine speed of 2000 rpm was best for the effective seedling uprooting in terms of bed thickness, time of operation, wheel slip and plant damage. For this final prototype field performance characteristics like field capacity, field efficiency and fuel consumption were assessed. The theoretical field capacity was computed as 163.33 m2h-1 and field efficiency was found to be 81.2 per cent. The observed fuel consumption for the final prototype was in the range of 0.51 to 0.53 l.h-1. At the present wage rate of Rs 300 per day, the total cost for uprooting and washing of seedlings for cultivating an area of one hectare by manual method is about Rs 750. The total cost for uprooting and washing of seedlings for cultivating an area of one hectare by using machine is Rs 250. Hence a saving of Rs 500 can be expected by using the developed machine for preparing the seedlings required for cultivating one hectare.
Open Access
Impact of climate change and watershed development on river basin hydrology using SWAT – a case study
(Department of irrigation and drainage engineering, Kelappaji college of agricultural engineering and technology, Thavanur, 2016) Anu Varughese; KAU; Hajilal, M S
Climate change is considered as a global phenomenon, but investigation at the regional level is essential to understand the changes induced, and to suggest suitable adaptation strategies. This study is mainly concerned with the analysis of possible changes in the hydrology of Bharathapuzha river basin in the state of Kerala, India. Initially the trend in historic climate data was analysed to get an idea about the changes happening in the area. The trend analysis of gridded data using Mann-Kendall and t-test showed that the mean, maximum and minimum temperatures during 1951-2013 showed a significant increasing trend and the increase in mean, maximum and minimum temperatures during the period was at the rate of .07°C/decade, 0.14°C/decade and 0.04°C/decade respectively. Trend analysis of gridded rainfall data for the period 1971-2005 showed statistically significant decreasing trend, at the rate of 15 mm/year. Trend analysis of seasonal rainfall indicated that there was no significant trend in seasonal rainfall except during the south-west monsoon period when there was an increasing trend. To find out the best suitable climate model for the region, the downscaled reanalysis data on precipitation and temperature from five regional climate models (RCM’s) derived from different Global Climate Models (GCM’s) were compared with observed data of area on the basis of the four statistical parameters (standard deviation, correlation coefficient, coefficient of variation and centred root mean square difference). The GFDL-CM3 RCM gave better comparison with the observed data and hence was used for further data analysis. Bias in precipitation was corrected using power transformation which corrects the mean and coefficient of variation (CV) of the observations. Since temperature is approximately normally distributed, it was corrected by fitting it to the mean and standard deviation of the observations. The model data for two emission scenarios RCP4.5 and RCP8.5 and two scenario periods 2041-70 and 2071-99 were selected for the study. Comparison of the post-processed climate data to observed climate data was carried out. Based on the results obtained, the annual maximum and minimum temperatures is expected to increase in future. It is also predicted that there will be a decrease of 4 to 7 per cent in average annual rainfall during 2041-70 compared to the present day average values, whereas the decrease will be up to 10 to 15 per cent during 2071-99. To evaluate the surface runoff generation and soil erosion rates from the area, the Soil and Water Assessment Tool (SWAT) model was used. The model was calibrated and validated on a monthly basis using the observed data and it could simulate surface runoff and soil erosion to a good level of accuracy. The model evaluation statistics used for the calibration and validation periods were Nash-Sutcliffe Efficiency (NSE), Coefficient of determination (R2) and PBIAS. The study demonstrated that the SWAT model can be used to predict the monthly stream flow and sediment loss from the basin. So the calibrated and validated model was then used for studying the impact of changes in climate and watershed interventions on the hydrology of the river basin. The model predicts 15 to 20 per cent decrease in stream flow by the end of the century if the worst situation of climate change continues (RCP8.5). While analysing the water balance components, it is seen that ET ranges from 15 to 22 per cent of the annual rainfall in the current scenario, while it may increase to 29 to 32 per cent in the RCP4.5 scenario and 32 to 35 per cent in RCP8.5 scenario. Lateral flow component is the lowest, comprising only 8 to 10 per cent of the total rainfall and there is no much variation for this component within the scenarios. Monthly streamflow predicted for the two periods 2041-2070 and 2071-2099 when compared with the current scenario values shows that irrespective of the scenarios, the streamflow is found to be less than that of the current scenario in almost all months. During 2046-2070, the sediment loss in RCP4.5 scenario is predicted to be much less than the RCP8.5 scenario, whereas to the end of the century, the sediment loss in RCP8.5 scenario is greater than RCP4.5 scenario in almost all years, and the annual sediment loss goes up to 7 to 9 t/ha, from the present condition of 2.5 to 4 t/ha.The impact of watershed interventions on the river hydrology was studied based on 0.05, 0.1 and 0.2 per cent increase in Water Retention Structures (WRS) in the area. The monthly stream flow simulated for the period 2007 to 2011 after adding WRS showed that even though the annual river flow decreased, the flow during the summer months (base flow) increased after adding the WRS and the percent increase in flow was highest during the months of January to April when the river has a very lean flow. Rather than utilizing the stored water in the upper reaches for irrigation and domestic purpose, the increase in summer flow will be helpful for maintaining a better environmental flow regime. Though the decrease in annual streamflow due to the WRS is small (1 to 6 per cent), the redistribution of peak flow to the summer months is significant. The annual streamflow in the current scenario is found to be decreasing with increasing capacity of the water storage structures. Streamflow prediction for the period 2041-2069 under the two scenarios RCP4.5 and RCP8.5 with WRS showed that the monthly stream flow could be increased by 5 to10 per cent due to the addition of the WRS during December to March. The water stored on account of increased WRS can be utilized for irrigation and domestic purpose in the upper reaches and at the same time the increase in summer flow will be helpful for maintaining a better environmental flow regime.
Open Access
Tank mix application of cyhalofop-butyl with selected herbicides for weed control in wet seeded rice
(College of Horticulture, Vellanikkara, 2016) Atheena, A; KAU; Prameela, P
Herbicidal weed control is very common in rice cultivation. Application of pre- emergence and post emergence herbicides or two post emergence herbicides as follow up sprays is usually recommended to take care of diverse weed flora in rice. As this increases the cost incurred in spraying, farmers prefer single spray of a mixture of herbicides or a broad spectrum herbicide. Cyhalofop-butyl is a common cost effective post emergence selective herbicide that controls grass weeds, especially the rice associated weed Echinochloa spp. and Leptochloa chinensis. The present study was carried out to study the efficacy and economics of tank mix application of cyhalofop-butyl with selected herbicides (pre emergence, post emergence and early post emergence) and to study the response of weed flora to tank mix application. A field experiment was conducted in Alappad kole lands from September 2015 to January 2016, using the rice variety Uma (MO-16). There were a total of 16 treatments replicated thrice. Almix® [chlorimuron-ethyl (10%) + metsulfuron-methyl (10%)], ethoxysulfuron, carfentrazone-ethyl, pyrazosulfuron-ethyl, pretilachlor, pendimethalin were tank mixed with cyhalofop-butyl and were also applied as follow up sprays, two days after cyhalofop-butyl application. For better comparison, sole application of cyhalofop-butyl, as well as a broad spectrum post emergence herbicide, bispyribac sodium, were also included apart from hand weeded and unweeded controls. Pre emergence herbicides were sprayed at six days after sowing (DAS), and early post emergence herbicide at 10 DAS. All tank mix herbicide applications were done at 18 DAS and follow up post emergence herbicide applications at 20 DAS (i.e., two days after the application of cyhalofop-butyl). Hand weeding was carried out at 20 DAS and 40 DAS. The data on weed spectrum revealed that broad leaf weeds and grasses were dominant and at 30 DAS they constituted 47 per cent and 46 per cent of the population respectively, whereas sedges constituted only 7 per cent. Echinochloa stagnina was the dominant grass and Monochoria vaginalis, the dominant broad leaf weed. Among tank mix applications of herbicides, cyhalofop-butyl + pyrazosulfuron-ethyl recorded the least weed dry matter production while among various sequential application of herbicides, the lowest weed dry matter accumulation was noted in cyhalofop-butyl followed by (f.b.) Almix® and both were statistically comparable. Among various herbicides and herbicide mixtures, both tank mix and sequential applications of carfentrazone-ethyl caused severe phytotoxicity in rice. However, the crop recovered by seven days after spraying and plant growth parameters were not affected with all the treatments registering comparable plant height at all stages. At both 30 DAS and 60 DAS, hand weeded treatment registered the highest tiller count. However, this was on par with bispyribac sodium, pyrazosulfuron-ethyl + cyhalofop-butyl and cyhalofop-butyl f.b. Almix®. Highest and statistically superior grain yield was registered in hand weeded treatment. Application of cyhalofop-butyl + pyrazosulfuron-ethyl and bispyribac sodium were the next best treatments with respect to grain yield and were superior to all other treatments. Except for pyrazosulfuron-ethyl all other herbicides resulted in lower grain yields when tank mixed with cyhalofop-butyl with weed index in the range of 13to 18 per cent and weed control efficiency in the range of 61 to 76 per cent (at 30 DAS). Application of follow up sprays of herbicides for control of broad leaf weeds after cyhalofop-butyl resulted in grain and straw yields comparable to that of single application of bispyribac sodium, which recorded a higher B:C ratio of 2.4. From this study it can be concluded that tank mix application of cyhalofopbutyl with pyrazosulfuron-ethyl at 18 DAS can be recommended for effective control of mixed weed flora in wet seeded rice as this treatment resulted in the highest B:C ratio (2.5) as well as net returns. It is not advisable to go for tank mixing of cyhalofop-butyl with Almix® as it will lead to complete loss of activity of cyhalofopbutyl. Tank mixing of pre emergence herbicides with cyhalofop-butyl was found to be less effective than their sequential application.
Unknown
Development of seedling uprooting unit for system of rice intensification
(College of Agricultural Engineering and Technology, Kelappaji, 2016) Sreerag, P M; KAU; Shivaji, K P
The present study was conducted to develop a seedling uprooting machine for System of Rice Intensification (SRI). System of Rice Intensification is a method developed in Madagascar in the early 1980’s, where, it has been shown that yields can be enhanced by suitably modifying certain management practices such as controlled supply of water, planting of younger seedlings and providing wider spacing. In this method 12 to 15 days old root washed seedlings are transplanted on the well puddled field. Only one younger seedling is transplanted per hill with row to row and hill to hill spacing of 25 cm. The preparation of seedlings for this method involves uprooting from nursery and washing the roots. This is done manually and no mechanical device for uprooting seedlings is available at present. In this circumstance, there is a need for the mechanization in the uprooting, washing and feeding the seedling to root washed transplanter. On this ground a seedling uprooting unit for system of rice intensification was developed and field tested. The seedling uprooting unit was consists of four major components namely bed cutting tool, conveyor unit, main frame and power unit. In order to cut the required thickness of soil bed, cutting tool was developed and fabricated with MS flat sheet of 2mm thickness. It consists of a rectangular base plate (25×30 cm) placed horizontally beneath the cutting blade. The cut seedling beds were conveyed through a slatted belt type conveyor having two adjacent roller chains inter linked with MS flat linkages giving overall belt width of 25 cm and 155 cm belt length. In order to drive the conveyor belt, a power unit from the existing vertical conveyor reaper was chosen. It consisted of 4 hp gasoline engine. According to the geometry of power unit a suitable frame was fabricated using MS angles (3×3 cm) to attach the cutting and conveying unit. The developed seedling uprooting unit was tested in the field to optimize the speed of operation and angle of cutting. Three levels of angle of blade viz., 20, 30 and 40 degrees and three levels of engine speed viz., 1000, 2000 and 3000 rpm were selected for the study. The thickness of bed, time of operation, wheel slip and plant damage were tested with respect to the above selected cutting angles and engine speeds. From the field observations it was found that cutting angle of 30° with engine speed of 2000 rpm was best for the effective seedling uprooting in terms of bed thickness, time of operation, wheel slip and plant damage. For this final prototype field performance characteristics like field capacity, field efficiency and fuel consumption were assessed. The theoretical field capacity was computed as 163.33 m2h-1 and field efficiency was found to be 81.2 per cent. The observed fuel consumption for the final prototype was in the range of 0.51 to 0.53 l.h-1. At the present wage rate of Rs 300 per day, the total cost for uprooting and washing of seedlings for cultivating an area of one hectare by manual method is about Rs 750. The total cost for uprooting and washing of seedlings for cultivating an area of one hectare by using machine is Rs 250. Hence a saving of Rs 500 can be expected by using the developed machine for preparing the seedlings required for cultivating one hectare.
Open Access
Investigations on energy conversion of waste coconut water through an Up-flow Anaerobic Hybrid Bioreactor
(College of Agricultural Engineering and Technology, Kelappaji, 2016) Dayanand Kumbar, Kumbar; KAU; Shaji James P, James P
Many Agro-industries discharges considerable amount of wastewater to water bodies. Anaerobic digestion of organic effluents from agro-industries has a great importance in pollution abatement as well for renewable energy production. Waste coconut water (WCW) is a medium strength waste water for which high rate anaerobic treatment is an affordable technology. This technology offers simultaneous production of energy in the form of biogas along with pollution control. Conventional biogas plants are slow in operation with long Hydraulic Retention Times (HRTs) in the order of 35 to 55 days, necessitating very large digester volumes. Hence, anaerobic treatment of WCW is technically and economically feasible only through high rate bioreactors, where we can reduce the HRTs in the range of 6 to 8 days. Hence, an investigation was taken up to study the performance of a high rate bioreactor viz. Up-flow Anaerobic Hybrid Bioreactor (UAHBR) for biomethanation of WCW. It was revealed that the WCW had a low pH along with high Bio-chemical Oxygen Demand (BOD) and Total Solids (TS). The semi-continuous digestion WCW was carried out in a lab scale floating gas holder digester. The digester was operated at different HRTs of 35, 30 and 25 day and performance evaluated. During all HRT there was a profound effect of pH over the working of the digester. The maximum daily biogas production and biogas productivity were 21.9 L and 3.5 L.L-1 during 30-day HRT. The TS reduction had the maximum value of 51.94 at 35-day HRT. The performance of the digester deteriorated at 25 day HRT and the minimum reduction was only 1.38 %. The system showed signs of failure. Existing full scale UAHBR was operated at different HRTs of 16.67 and 15 day and performance evaluated. The reactor was stable in operation throughout the period of operation and revealed high organic reduction with biogas production. The maximum specific biogas production and biogas productivity were 354.31 Lkg1TSadded and 13.50 L.L-1 during 15-day HRT. The TS reduction was in the range of 79.35 and 81.40 during the period of 15-day HRT.Experimental UAHBR was fabricated and performance evaluated at different HRTs of 15, 12, 10, 8 and 6 day. Reactor was stable in operation during 15, 12, 10, 8 and 6 day HRTs and exhibited high process efficiency characterised by good organic reduction and biogas production. The performance was slightly deteriorated with 8 and 6-day HRT. The maximum daily biogas production and volumetric biogas production were 114 L and 877 L.m-3 for 6-day HRT. The maximum specific biogas production and biogas productivity were 225.73 L.kg-1TSadded and 8.7 L.L-1 during 15-day HRT.
Open Access
Impact of climate change and watershed development on river basin hydrology using SWAT – a case study
(Kelappaji College of Agricultural Engineering and Technology, Thavanur, 2016) Anu, Varughese; KAU; Hajilal, M S
Climate change is considered as a global phenomenon, but investigation at the regional level is essential to understand the changes induced, and to suggest suitable adaptation strategies. This study is mainly concerned with the analysis of possible changes in the hydrology of Bharathapuzha river basin in the state of Kerala, India. Initially the trend in historic climate data was analysed to get an idea about the changes happening in the area. The trend analysis of gridded data using Mann-Kendall and t-test showed that the mean, maximum and minimum temperatures during 1951-2013 showed a significant increasing trend and the increase in mean, maximum and minimum temperatures during the period was at the rate of .07°C/decade, 0.14°C/decade and 0.04°C/decade respectively. Trend analysis of gridded rainfall data for the period 1971-2005 showed statistically significant decreasing trend, at the rate of 15 mm/year. Trend analysis of seasonal rainfall indicated that there was no significant trend in seasonal rainfall except during the south-west monsoon period when there was an increasing trend. To find out the best suitable climate model for the region, the downscaled reanalysis data on precipitation and temperature from five regional climate models (RCM’s) derived from different Global Climate Models (GCM’s) were compared with observed data of area on the basis of the four statistical parameters (standard deviation, correlation coefficient, coefficient of variation and centred root mean square difference). The GFDL-CM3 RCM gave better comparison with the observed data and hence was used for further data analysis. Bias in precipitation was corrected using power transformation which corrects the mean and coefficient of variation (CV) of the observations. Since temperature is approximately normally distributed, it was corrected by fitting it to the mean and standard deviation of the observations. The model data for two emission scenarios RCP4.5 and RCP8.5 and two scenario periods 2041-70 and 2071-99 were selected for the study. Comparison of the post-processed climate data to observed climate data was carried out. Based on the results obtained, the annual maximum and minimum temperatures is expected to increase in future. It is also predicted that there will be a decrease of 4 to 7 per cent in average annual rainfall during 2041-70 compared to the present day average values, whereas the decrease will be up to 10 to 15 per cent during 2071-99. To evaluate the surface runoff generation and soil erosion rates from the area, the Soil and Water Assessment Tool (SWAT) model was used. The model was calibrated and validated on a monthly basis using the observed data and it could simulate surface runoff and soil erosion to a good level of accuracy. The model evaluation statistics used for the calibration and validation periods were Nash-Sutcliffe Efficiency (NSE), Coefficient of determination (R2) and PBIAS. The study demonstrated that the SWAT model can be used to predict the monthly stream flow and sediment loss from the basin. So the calibrated and validated model was then used for studying the impact of changes in climate and watershed interventions on the hydrology of the river basin. The model predicts 15 to 20 per cent decrease in stream flow by the end of the century if the worst situation of climate change continues (RCP8.5). While analysing the water balance components, it is seen that ET ranges from 15 to 22 per cent of the annual rainfall in the current scenario, while it may increase to 29 to 32 per cent in the RCP4.5 scenario and 32 to 35 per cent in RCP8.5 scenario. Lateral flow component is the lowest, comprising only 8 to 10 per cent of the total rainfall and there is no much variation for this component within the scenarios. Monthly streamflow predicted for the two periods 2041-2070 and 2071-2099 when compared with the current scenario values shows that irrespective of the scenarios, the streamflow is found to be less than that of the current scenario in almost all months. During 2046-2070, the sediment loss in RCP4.5 scenario is predicted to be much less than the RCP8.5 scenario, whereas to the end of the century, the sediment loss in RCP8.5 scenario is greater than RCP4.5 scenario in almost all years, and the annual sediment loss goes up to 7 to 9 t/ha, from the present condition of 2.5 to 4 t/ha.The impact of watershed interventions on the river hydrology was studied based on 0.05, 0.1 and 0.2 per cent increase in Water Retention Structures (WRS) in the area. The monthly stream flow simulated for the period 2007 to 2011 after adding WRS showed that even though the annual river flow decreased, the flow during the summer months (base flow) increased after adding the WRS and the percent increase in flow was highest during the months of January to April when the river has a very lean flow. Rather than utilizing the stored water in the upper reaches for irrigation and domestic purpose, the increase in summer flow will be helpful for maintaining a better environmental flow regime. Though the decrease in annual streamflow due to the WRS is small (1 to 6 per cent), the redistribution of peak flow to the summer months is significant. The annual streamflow in the current scenario is found to be decreasing with increasing capacity of the water storage structures. Streamflow prediction for the period 2041-2069 under the two scenarios RCP4.5 and RCP8.5 with WRS showed that the monthly stream flow could be increased by 5 to10 per cent due to the addition of the WRS during December to March. The water stored on account of increased WRS can be utilized for irrigation and domestic purpose in the upper reaches and at the same time the increase in summer flow will be helpful for maintaining a better environmental flow regime.
Open Access
Modelling the hydrology of watershed by using HEC-HMS
(Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2016) Makkena, Jyothi; KAU; Vishnu, B
A hydrological model is a commonly used tool to estimate the hydrological response of a watershed to precipitation. Hydrologic Modeling System (HEC-HMS) is a physically based semi-distributed hydrologic modelling software developed by the Hydrologic Engineering Center (HEC) of the U.S. Army Corps of Engineers. It is designed to simulate the complete hydrologic processes of dendritic watershed systems under various widely varying geographic conditions. HEC-HMS is widely used and includes both traditional hydrologic analysis procedures such as event infiltration, unit hydrographs, and hydrologic routing as well as continuous simulation procedures including evapotranspiration, snowmelt, and soil moisture accounting. It can be used in conjunction with other software for studies of water availability, urban drainage, flow forecasting, future urbanization impact, reservoir spillway design, flood damage reduction, floodplain regulation, and systems operation. In the present study, Hydrologic Modeling System (HEC-HMS) is calibrated and validated for Thuthapuzha sub basin of Bharathapuzha river basin in Kerala. The input data required for the model like precipitation, meteorological parameters, river discharge, soil characteristics, land use characteristics and topographical characteristics of the study area were collected from various agencies like Central Water Commission (CWC), Kerala State Land Use Board (KSLUB), RARS Pattambi and the Bhuvan geo-data portal of National Remote Sensing Centre (NRSC). The model performance of the calibrated HEC-HMS model for Thuthapuzha watershed was evaluated using the statistics -Nash Sutcliffe- model efficiency criterion, coefficient of determination and simulated time to peak. The analysis showed that CN, and lag time are the most sensitive parameters for the simulation of stream flow. The Nash-Sutcliffe model efficiency (E) was (0.77-0.8) and (0.86-0.88) and the coefficient of determination was (0.82- 0.91) and (0.91-0.93) before and after the calibration respectively, indicating the good performance of the model.

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