Development of a GIS Based Water Management Tool for a Large Scale Rice Irrigation Scheme

A GIS based model was developed to integrate the vast amounts of spatially distributed information from the Kerian Irrigation Scheme comprising eight compartments which are further subdivided into 28 blocks. The model consists of three modules. The "Scheduling" program computes irrigation deliveries based on spatial and temporal demand of the paddy field by each compartment, block or secondary canal. The "Monitoring" program gives information by compartment and by block on the uniformity of water distribution and the shortfall or excess. Relative Water Supply (RWS), Water Use Efficiency (WUE), Cumulative Relative Water Supply (CRWS), and Water Productivity Index (WPI) were computed by the "Evaluation" module. The post-season analysis uses weekly information on hydro-climatic parameters, irrigation delivery and irrigation indices by block within each compartment. On a weekly basis, RWS and WUE were found to range from 1.01 to 2.24 and 45% to 99% respectively in the main season and 1.01 to 1.87 and 53.57% to 96.15% respectively in the off season. The average values of RWS and WUE were found to be 1.53 and 68.15% in the main season and 1.33 and 78.47% in the off season respectively. The average values of WPI were also found to be 0.13 and 0.22 kg/m3 in the main season and off seasons respectively. Color-eoded thematic maps were produced for the monitoring of Seasonal Yields and Cropping Intensity (CI) by block and compartment of the scheme. The results are displayed allowing the manager to view maps, tables and graphs in a comprehensible form to ease decision making as the season progresses. This study would be useful to improve the irrigation system management based on feedback of field information

The influence of magnetized water on soil water dynamics under drip irrigation systems

Soil water dynamics under drip irrigation systems are of considerable importance in designing, managing and operating these systems. Emitter discharge, soil type, soil chemical properties, crop water-requirements, and quality of applied water are the main factors affecting soil water dynamics under drip irrigation. In this study, laboratory experiments were conducted to study the effect of magnetized water on wetting pattern dimensions and water content distributions under surface emitter. Passing water through permanent or electro magnets installed on feeding pipeline resulted in producing magnetized water. Two emitter discharges (3 and 4.5 l/h, in average), two soil types (sand and clay), two soil profiles (homogeneous and layered-textural) and two water types (plain and magnetized water) were considered in the experiments. It was found that using magnetized water led to increase surface wetted radius by 6.2% and decrease vertical wetted depth by 6.3% in homogeneous soil profiles. In layered-textural soil profiles, the surface wetted radius slightly decreased by 1.8% while the vertical wetted depth increased by 7.0% in case of sand over clay and decreased by 2.0% in case of clay over sand when using magnetized water. As a result of using magnetized water, the total wetted area decreased for homogeneous profiles and increased for layered-textural profiles. It was concluded that the impact of magnetized water is statistically significant on wetted bulb dimensions and not statistically significant on water content distributions. The results revealed that using magnetized water is recommended especially in homogeneous soil profiles

Optimization of equitable irrigation water delivery for a large-scale rice irrigation scheme

Equitable water allocation is essential in an irrigation scheme for obtaining potential crop yields from the entire scheme, especially when water supply is inadequate. An optimization model achieved this goal by coupling an optimal water allocation model with available water supply and irrigation water demand for a river-fed rice irrigation system in Malaysia. This model consists of a paddy field water balance module and an optimization module. The outputs from the module are daily irrigation demand and surface runoff, if there is any. The optimization module consists of an objective function, which minimizes water shortage across the scheme area while maintaining equity in water allocation. This model performs optimization subject to several system constraints, and the decision variable of the model is daily releases or supply to the tertiary canals. Performance of this model remained unaffected under different water supply conditions, and the optimization model reliably examined the effects of alternate water allocation and management rules with field information. It improves efficiency and equity in water allocation with respect to crop growth stages and water shortages rather than simply cutting irrigation supply on a proportional basis to overcome water shortages

Simulation of future daily rainfall scenario using stochastic rainfall generator for a rice-growing irrigation scheme in Malaysia

Rainfall is an important component in paddy water demand model for determining daily irrigation requirements. Knowledge of how it is likely to evolve in future is therefore indispensable for paddy farming. This paper presents a quantitative assessment of the possible changes in future rainfall performed by downscaling GCM simulations for the Tanjung Karang irrigation scheme in Malaysia. The stochastic rainfall generator model (WGEN), never applied in Malaysia before, was adopted for downscaling and simulation of future daily rainfall using 16 simulations developed from 10 GCMs driven by the latest Representative Concentration Pathways scenarios (RCPs), 6.0 and 8.5 for two future periods (2030s and 2060s). Change factors were computed from the GCMs using the delta change method which were used in perturbing model parameters for future simulationof rainfall. The results obtained show a wide spread among GCMs, although they all agree in the direction of future rainfall changes. Overall annual rainfall is predicted to increase by 6% and 14% for dry and wet seasons, respectively under RCP6.0 and 8.5 scenarios. Additionally, seasonal effective rainfall projections show a decreasing change of 5% during dry season under RCP6.0, while an increase change of 8 to 13%is predicted in wet season from moderate (RCP6.0) to the most severe (RCP8.5) scenarios respectively. This is an area of concern that farmers and water managers may need to keep alert so as to secure future paddy irrigation water. Theprojected changes in rainfall regimerequire further work before concluding whether these changes have negative or positive consequences for the paddy sector. The stochastic model will be adopted as a component in a future study aimed at developing a water management-support tool for modeling water allocations and irrigation schedules in paddy fields

Thin layer drying of hybrid rice seed

This paper presents thin layer drying characteristics of hybrid rice seed and quality of the dried rice seed in terms of germination capacity and colour. Thin layer drying of hybrid rice seed was conducted at the temperature levels of 40 °C, 50 °C and 60 °C, relative humidity ranging 10 to 15% and air velocity ranging 0.55 to 0.65 m/s. Drying rate increases with the increase in drying air temperature and the drying air temperature has a significant effect on the seed quality. Five thin-layer drying models were fitted to the experimental data of thin layer drying of hybrid rice seed. Midilli equation was found to be the best followed by two term exponential equation, Page equation, Henderson and Pabis equation and Newton model. The agreement between the predicted and experimental results was excellent. Germination capacity was the highest for the drying air temperature of 40 °C and then it decreased significantly with the increase of drying air temperature above 40 °C. Colour of the hybrid rice seed did not change with the increase of drying temperature. Lightness, hue angle and chroma were found to be almost same for these three drying air temperatures. It is recommended that hybrid rice seed should not be dried above 40 °C

Municipal solid waste generation, composition and management: issues and challenges: a case study

Khulna is the third largest metropolitan city in Bangladesh and a centre with intensive commercial and industrial activities. Rapid urbanization and increased migration of people from rural and coastal areas has put tremendous pressure on its existing solid waste management. The status of the existing municipal solid waste (MSW) management tiers such as generation, source storage, collection, on-site storage, transportation, and open dumping has been identified in this study. The daily generation of MSW is estimated as 520 Mg, of which food and vegetable wastes are the main components (79% on average). The major source of generated MSW is residential areas, which is 85.87% of total generation, whereas 11.60% in commercial areas, 1.02% in institutional areas, 0.55% in street sweeps and 0.96% in other areas. About 50% of total generated waste is disposed daily to the dumping site and the rest remains uncollected and unmanaged. Non-governmental organizations and community based organizations play an important role in primary collection, composting of organic wastes and medical waste management

Uncertainty analysis of rainfall depth duration frequency curves using the bootstrap resampling technique

Rainfall depth duration frequency (DDF) curves are used extensively in many engineering designs. However, due to the sampling error and the uncertainty associated with the parameter estimation process, the DDF curves are subjected to parameter uncertainty. In this study, an evaluation of the uncertainty of the DDF curves in the Kelantan river basin was performed using the bootstrap resampling method. Annual maximum rainfall series for durations of 24, 48, 72, 96 and 120 h were derived from the stochastic rainfall model outputs and fitted to the generalised extreme value (GEV) distribution. The bootstrap samples were generated by resampling with replacement from the annual maximum rainfall series. The relationships that describe the GEV parameters as a function of duration were used to establish the DDF curves. The 95% confidence intervals were used as an indicator to quantify the uncertainty in the DDF curves. The bootstrap distribution of the rainfall depth quantiles was represented by a normal probability density function. The results showed that uncertainty increased with the return period and there was significant uncertainty in the DDF curves. The suggested procedure is expected to contribute to endeavours in obtaining reliable DDF curves, where the uncertainty features are assessed. © 2019, Indian Academy of Sciences