Water Management for Kerian Irrigation Scheme Using Geographical Information System

A GIS-based model was developed to integrate the vast amounts of spatially distributed information of the Kerian Irrigation Scheme. The scheme has a command area of 24,000 ha, comprising eight compartments which is further subdivided into 28 blocks. The model requires the input of spatial and temporal information from various fields to compute irrigation deliveries for the upcoming period. It also runs periodic and seasonal monitoring and evaluation programs to improve water management of the scheme. The system permits display of information in the form of maps for easy visualization. The software Map Info Professional 4.5 was used to demonstrate the concepts and MapBasic Professional 4.5 programming language for the development of the user-interface tool. The scheduling program computes irrigation deliveries based on spatial and temporal demand of the paddy field by each compartment, block and Secondary Canal. The monitoring program gives information by compartment and by block at the end of each period on uniformity of water distribution to the field as well quantity to be delivered for the next period. The computed discharges were used to monitor the performance of irrigation delivery at the end of each period. Relative Water Supply (RWS), Water Use Efficiency (WUE), Cumulative Relative Water Supply (CRWS), Water Productivity Index (WPI) and Cropping Intensity (CI) have been used for monitoring and evaluation of the irrigation system performances. Hydro-climatological parameters like Evapotranspiration (ET), Effective Rainfall (ER), Irrigation Depth (IR) and Drainage Requirement (DR) also were computed. The post-season analysis provides weekly distribution of hydro-climatological parameters, irrigation delivery and performance by block. 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 53.6% to 96.2% 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 78.5% in the off season respectively. The average values of WPI were also found to be 0.1267 and 0.2171 kg/m3 in the main season and off season respectively. The color-coded thematic maps were produced for the monitoring of seasonal yields and cropping intensity by block and compartment of the scheme. The user-interface technique for the irrigation system promises to provide comprehensive results along with new data sets and improve the decision-making processes in the operation and management of the scheme. The computed results are rapidly displayed allowing the manager to view maps, tables and graphs in a more comprehensive form, allowing time to make appropriate decision as the season progresses. This technique was found to be for improving the irrigation system management along with the actual feedback of the field information

Dam breach parameters and their influence on flood hydrographs for Mosul dam

Dams breach geometry prediction is crucial in dam break studies. The characteristics of flood hydrographs resulting from a dam breach essentially depend on the breach geometry and the required time for breach formation. To investigate the impact of breach parameters on maximum breaching outflows, five breach prediction approaches were implemented to calculate the flood hydrographs using HEC-RAS model, for Mosul dam. Numerous reservoir water levels for each approach were considered. Sensitivity analysis was carried out to evaluate the effect of each parameter on the resulting flood hydrographs. The time and value of peak discharge for each scenario were analysed and discussed. Results show that the most suitable method for estimating breach parameters for Mosul dam was the Froehlich approach. Furthermore, the sensitivity analysis shows that the breach side slope does not affect the peak discharge time and has a minor influence on peak outflow values. Meanwhile, the required time for the breach to develop was highly sensitive to both peak discharge and peak discharge time

Irrigation management for rice using geographic information systems

Indicators and techniques of management system are important to evaluate the irrigation system. This study involves the evaluation of the management of an irrigation system spatially and temporally using Geographical Information Systems. It has great practical and application prospects, which can break down the single search method, and share graphics and databases and to present the results spatially on a map involved an efficient combination of information databases in rice irrigation system

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

Geospatial Water Productivity Index (WPI) for rice

A GIS-based user-interface programme was developed to compute the geospatial Water Productivity Index (WPI) of a river-fed rice irrigation scheme in Northwest Selangor, Malaysia. The spatial analysis includes irrigation blocks with sizes ranging from 20 to 300 ha. The amount of daily water use for each irrigation block was determined using irrigation delivery model and stored in the database for both main season (August to December) and off season (February to May). After cut-off of the irrigation supply, a sub-module was used to compute the total water use including rainfall for each irrigation block. The rice yield data for both seasons were obtained from DOA (Department of Agriculture, Malaysia) of the scheme. Then, the Water Productivity Index (WPI) was computed for each irrigation block and spatial thematic map was also generated. ArcObjects and Visual Basic Application (VBA) programming languages were used to structure user-interface in the ArcGIS software. The WPI, expressed in terms of crop yield per unit amount of water used (irrigation and effective rainfall), ranged from 0.02 to 0.57 kg/m3in the main season and 0.02 to 0.40 in off season among irrigation blocks, respectively. The development of the overall system and the procedure are illustrated using the data obtained from the study area. The approach could be used to depict the gaps between the existing and appropriate water management practices. Suitable interventions could be made to fill the gaps and enhance water use efficiency at the field level and also help in saving irrigation water through remedial measures in the season. The approach could be useful for irrigation managers to rectify and enhance decision-making in both the management and operation of the next irrigation season

A modified empirical model for estimating the wetted zone dimensions under drip irrigation

Drip irrigation system has become one of the most common irrigation systems especially in arid and semi-arid regions due to its advantages in saving water. One of the most essential considerations in designing these systems is the dimensions of the wetted soil volume under emitters. These dimensions are significant in choosing the proper emitter spacing along the laterals and the suitable distance between laterals. In this study, a modified empirical equations for estimating the horizontal and vertical extend of the wetted zone under surface emitters were suggested. Data from published papers includes different conditions of soil properties and emitter discharge were used in deriving the empirical model using the nonlinear regression. The developed model has high value for coefficient of determination, R2. The results from the developed model were compared with results of other empirical models derived by other researchers. Some statistical criteria were used to evaluate the model performance which are the mean error ME, root mean square error RMSE, and model efficiency EF. The results revealed that the modified model showed good performance in predicting the wetted zone dimensions and it can be used in design and management of drip irrigation systems

Effects of crop evapotranspiration estimation techniques and weather parameters on rice crop water requirement

Accurate estimation of crop evapotranspiration is key to determination of crop water requirements as well as water productivity. In this study, Microflex-C sensors were mounted on three sets of lysimeter to measure crop evapotranspiration in the paddy fields of the Tanjung Karang Rice Irrigation Scheme. Evapotranspiration was obtained from water level recorded at 15 minutes interval for the entire irrigation season. The readings were carried out starting from middle of January to end of April 2012. Measured crop evapotranspiration were compared with estimated evapotranspiration from weather data using penman Monteith method. These evapotranspiration values were used to determine the actual crop water requirement of MR219 rice (Oryza sativa) variety. The lysimeter and weather data estimates showed that 37% and 48% of the total water supplied was enough to meet the actual crop water requirement. Sensor based Microflex-C readings from the lysimeter measurements reveals that less water was required to meet actual crop water requirement compared to estimated methods. The actual average daily crop evapotranspiration for the growing season were 4.1, 3.9 and 4.0 mm/day for the month of February, March and April, respectively. The average water productivity index was determined using the lysimeter reading and weather data were found to be 10.1kg/ha-mm and 7.8kg/ha-mm respectively

Improving irrigation water delivery performance of a large-scale rice irrigation scheme

The availability of irrigation water and its equitable allocation in a large-scale rice irrigation scheme of Malaysia have been modeled. The model reliably estimates available water for irrigation at the intake of the main canal and simulates the recommended irrigation deliveries for 120 tertiary canals. Different water allocation and management scenarios were evaluated based on the sensitivity of the growth stages of rice to water, varying field-water demand, and perceived water shortages. The model provides a quantitative assessment not only of water allocation for irrigation but also of day-to-day or periodic irrigation delivery performances for a large-scale rice irrigation system. It provides 86% adequacy and 87% equity of irrigation delivery in the main season (August-December). The corresponding performance indicators provided by the model are 74 and 89% in the off-season (February-June). The dependability of water supply is higher in the off-season than in the main season, while the relative water supply (RWS) is the converse. RWS often becomes >1.0 in the main season, while such a RWS is rarely obtained in the off-season. The model augments the water delivery performance of the scheme and hence would serve as a useful tool for irrigation managers in decision making

Assessment of distillate water quality parameters produced by solar still for potable usage

In this study, a few field experiments were conducted on a simple solar still and water quality analyses were done in laboratory to check the contaminants removal efficiency from raw water samples. A few water quality parameters such as pH, redox, electrical conductivity (EC), salinity, total dissolved solids (TDS), Escherichia coli and arsenic for the feed (before distillation) and product water (after distillation by a solar still) were obtained. A wide range of water samples (e.g. seawater, pond water, and arsenic contaminated groundwater) were collected from various locations in Malaysia and Bangladesh. A few synthetic saline water samples (e.g. 1, 2, 3 and 5% salt) were also prepared. The values of pH (6.5-7.5), redox (100-200 mV), EC (< 750 mS/cm) of the product water were found within the standard ranges. The average removal efficiencies of more than 24 and 99% were obtained from repetitive tests run on salinity and arsenic, respectively. The still was also successful in removing pathogenic bacteria by more than 80%. These obtained parameters of the product water were then compared with various drinking water standards and found that most of the values obtained were within the acceptable ranges provided by the standards. Finally, it is concluded that the solar still is able to produce potable water and can be installed to remove the water scarcity in coastal and arid regions