Browsing by Author "Parvathy, S"

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Determination of constants in uniform flow formula for small discharges in open channels
(Department of Land and Water Resources and Conservation Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 1990) Parvathy, S; George, T P
An attempt was made to find out the constants in the general uniform flow formula for small discharges less than 10 1/s in cement lined and earthen channels. These constants were compared with the constants in the well known and widely used uniform flow formulae such as Manning’s and Chezy’s equation and checked their validity for small channels. Experiments were conducted for different discharges varying from 1 to 9 1/s and for different slopes of 1/2000, 1/3000, 1/4000 and 1/5000 in cement lined and earthen channels. With the help of a computer, analysis was made to establish a relationship between velocity v, hydraulic radius R and slope S. The expirical equation obtained are In cement lined channel V = 9.199 R0.7591 S0.1103 i.e. V = 1/0.1087 R0.7591 S0.1103 In earthen channel V = 47.2286 R0.844 S0.307 i.e. V = 1/0.0212 R0.844 S0.307 From the comparison of actual velocity with velocity obtained by using Manning’s equation, it was found that Manning’s equation was not applicable to small channels having discharges less than 10 1/s. In both the channels, actual velocity was roughly two times greater than the Manning’s velocity. The average ratio of actual and computed velocity using the best fit equations and the coefficient of determinations in the two cases were near unity. Hence the best fit equations obtained in the study are recommended for the design of small channels. Manning fixed the value of exponent of S as 0.5 based on some theoretical assumptions. So it was decided to find the value of n and the exponent of R in both the channels by fixing the value of exponent of S as 0.5. The equations obtained are In cement lined channel V = 1/0.00428 R0.7827 S0.5 In earthen channel V = 1/0.00408 R0.8696 S0.5 These equations were good but their reliability were less than that of the previous equations.Since Manning’s equation is an university accepted form, comparison was made between the recommended n values and the n values obtained in the study by fixing the value of exponent of R and S as 0.67 and 0.5 respectively. The equations obtained are In cement lined channel V = 1/0.00609 R0.67 S0.5 In earthen channel V = 1/0.00778 R0.67 S0.5 Though the reliability of these equations were comparatively less than the earlier cases, it gave reasonably good results. So these equations are also recommended for the design of small channels with different n values for cement lined and earthen channels. Chezy’s constant C was determined from the best fit equations by fixing the value of exponent of R and S as 0.5. The equations obtained in two channels are In cement lined channel V = 94.91√RS In earthen channel V = 74.771√RS These C values obtained are recommended for the design of small channels in Chezy’s equation than the C values obtained from Manning’s and Kutter’s equations using Manning’s recommended n values. Soil in which earthen channel was constructed was classified based on texture. Since the soil was sandy loam, the best fit equation obtained in earthen channel is applicable only for sandy loam soil.
Participation of women in agricultural development programmes under people`s plan in Thiruvananthapuram district
(Department of Agricultural Extension, College of Agriculture, Vellayani, 2000) Parvathy, S; Sobhana, G
Participatory action research for renumerative rice production
(Department of Agricultural extension, College of Horticulture, Vellanikkara, 2004) Parvathy, S; Ahamed, P
As with the Complex, Diverse and Risk- prone (CDR) rice systems of many Asian countries, the Kerala state of peninsular India suffers from the fast depleting paddies and the ' high cost- low remuneration syndrome'. Crucial rice technologies have been blamed by stakeholders for the insensitivity to micro farming situations A multidisciplinary stakeholder Participatory Action Research (PAR) of emancipatory type and collaborative mode was done for three years (2001-2004) on identification and prioritization of constraints to profitable rice production to explore the available cost-reducing and productivity increasing technological options. The project focussed on screening of technological modules through farmer participatory field assessment and arrived at locally adaptable and remunerative technology packages. The project also developed and standardised an extrapolatable stakeholder participatory assessment model and protocol. The programme had a blend of extension approaches, research designs and tools like "ex-post facto", benchmark appraisal through Participatory Learning and Action (PLA), exploratory, diagnostic, evaluative, field experiments and analytical studies. The PAR was done in two rice ecosystems (irrigated and rainfe:l) of the midland, laterite belt of Kerala state, India. Fourteen technology modules were fitted into the PAR, under .. , each of the three treatments, viz., farmers' practice, recommended packages of the formal research system and location specific I technology components" jointly decided by the research team extensionists and farmers. Each technology component was subjected to five types of analysis viz., agronomic, statistical, economic, farmers perceptions and reactions, post-trial follow up analysis of adoption in the succeeding cropping seasons. The participatory interventions significantly influenced the level of technical knowledge and extent of adoption of adaptable technology modules, typifying the cognitive impact of an emancipating action research. The short duration red rice varieties "Kanchana" (Ptb 50) and "Kairali" (Ptb 49) proved to be the best first crop and second crop varieties respectively, to replace the ruling cultivars. The technology modules recommended by the formal research system viz., seed treatment with fungicides for the first crop season and Pseudomonas fluorescence for the second crop season were adaptable technologies. The PAR came out with an efficient planting density and crop geometry package (line transplanting; 15 x 10 cm; 67 . , hills/m'; 2-3 seedlings/hill) to replace the conventional planting system. The existing formal recommendations including IPM and INM practices could enhance and combat weeds, pest and diseases thereby enhancing crop yield. Harvesting with self- propelled reaper and threshing with mechanised thresher were cost effective, drudgery alleviating and time saving. The net result of the action research was a set of adaptable technological package for remunerative rice production in the CDR rice production systems. Cognitive and behavioural impact on the participants; and the standard methodology and protocol for participatory technology validation for rice in particular, and for any farm enterprise in general, with extrapolative effect.