Introduction
The selected strategy is crop evapotranspiration irrigation. This irrigation strategy is based on the ability of crops to use water and lose the water to the atmosphere (evapotranspiration) as they grow (Hao 2006). Crop evapotranspiration is calculated by determining the crop factor and collecting climatic data. Crop factor involves consideration of development stages, variety, and crop type since these influence water intake rate of a crop. Moreover, crop water use is also influenced by climatic factors such as radiation, humidity, wind speed, and temperature. This enables the use of climatic data. The data obtained from crop factor and climatic conditions are fed to an irrigation control program in the form of millimetres (mm) of water usage. Such information is essential in triggering the occurrence of an irrigation event at a pre-set limit. This irrigation strategy helps in effective monitoring of rainfall events and soil moisture depletion.
The selected strategy has the advantages of ensuring a higher degree of uniformity in terms of water application (Hao 2006). This ensures that crops have an even uptake of water in the whole irrigation area. Further, the strategy ensures that the control of water application is effective. This limits instances of having under or over-irrigation of the land area. This occurs along having a higher distribution rate in comparison with other irrigation methods like surface and sprinkler irrigation. Moreover, the high rate of irrigation provides an opportunity for ensuring that soil moisture content is maintained at optimum levels within the root zone. This contributes towards the elimination of soil fluctuation, which is associated with inducing stress to crops.
In addition, this irrigation strategy requires smaller lateral and mains diameters, lower pressures, and low flow rates. This aids in saving energy, which would be used in the process of irrigation. These benefits prevail at all weather conditions. As such, wind conditions do not limit the strategy its ability to achieve the desired performance level. Furthermore, crop evapotranspiration irrigation is applicable to a range of different paddock shapes and sizes.
Nevertheless, this strategy has inherent limitations. One of these limitations is emitter clogging, which may develop because of insufficient water filtration, chemical injection or lateral flushing (Sharma, & Irmak 2012). Salt accumulation is another limitation when saline water is used for irrigation purposes. Salt accumulates at the laterals and results in hindering effective crop growth. Finally, soil structure is affected while using this strategy. This is evidenced in cases where clay content increases, magnesium: calcium ration changes, and sodium percentage increases. This needs periodic monitoring of the soil nutrient composition to ensure that the soil nutrient level is within the anticipated range.
Irrigation System
The irrigation system, which is to, be used for Melbourne has a structure as shown in figure 1. This system will comprise of five components, which are interlinked in order to perform the task of irrigating the land. These include pumping station, field application, and distribution, conveyance, and drainage systems. The pumping station acts as the intake point for water from a river or reservoir to the irrigation system (Hao 2006). The water then flows to a conveyance system, which transports water to ditches that act as the distribution system. Water within the distribution system is then transported to the field application system. The field application system is characterised of sprinklers, which ensure effective distribution and use of water for all crops within the irrigation system. The irrigation system has a drainage system, which will enable in the removal of excess water.
Alternatives
Viable alternative to crop evapotranspiration strategy is the use of the Crop Water Stress Index (CWSI). CWSI determines the temperature of the canopy in order to evaluate and measure crop water stress, which develops because of radiation, wind speed, air temperature, evaporative cooling and humidity. This strategy provides room for direct measurement of the usage of water by plants and determination of crop water stress in order to improve the timing of an irrigation event. Unfortunately, the strategy has limitations of not indicating the required volume of water, which should be applied, and it is only suitable for commercial scale use. This occurs since technological factors such as cost and availability of sensors, which are used in determining CWSI, influence the adoption of the strategy.
Potential
This irrigation strategy will contribute towards generating more water through water conservation. Water conservation will be ensured through adoption of an effective irrigation scheduling. Further, conservation of water will occur through residue management, increasing infiltration, minimizing surface runoff, and adopting minimum tillage strategies (Sharma, & Irmak 2012). These measures will ensure that the irrigation system does not take more water than it is expected to take. Moreover, the proposed strategy has the ability of covering a large acreage, which will ensure that Melbourne will attain cost effectiveness while using the strategy and solve its water problems in an effective manner.
Implementation
The implementation of the irrigation efficiency strategy for Melbourne, Australia is a task, which will contribute towards solving of the water problems in the region. This will involve ensuring that all the requirements for the irrigation system to be used as outlined in the cost section are available. This should be followed by accessing sufficient labour and machinery for land preparation for the irrigation system layout. This includes an access to tractors and professionals or experts on irrigation systems design. This will ensure that primary research on the potentiality of the location benefiting from irrigation efficiency as a means of solving water problems is conducted in an effective manner. Experts may also provide measures, which need to be taken in order to ensure that the irrigation system is designed in an effective manner in order to attain the desired success. The layout for the irrigation system should be implemented as indicated on figure 1. However, there is a room for alteration of the same in order to suit the terrain and soil structure of Melbourne land area.
The pump station for the irrigation system will deserve to have a power source. This means that energy will have been used in this strategy. Therefore, the source of energy for the pump station is recommended to be any of the renewable energy sources such as solar energy or wind energy. This will ensure that this strategy does not contribute towards enlargement of the global problem of the energy crisis. Operation of the pump station will call for training and education of community members. This is essential in order to ensure that community members are able to take data, feed on the control program, and run the pump station effectively. This will contribute towards attainment of cost savings in running the irrigation system.
Cost
The initial cost for this system may be high. This is because intensive labour is needed during the process of installation and laying out of the irrigation system structure. Further, crop evapotranspiration sensors for crop factor and climatic data collection will need to be acquired. This will be inclusive of the pump for the pumping station and equipping of the pump station with the necessary equipment and devices. Moreover, sprinklers for the application system will have to be purchased. Based on these requirements for the drainage system, it is estimated that the initial cost for the system has to be high, but the benefits from the system will surpass the cost within a short span of time.
Prior use
Texas is one state, which has recently completed a water planning strategy (Michelsen 2009). As such, the state has adopted crop evapotranspiration as an irrigation strategy, which will contribute towards improvement of production of crops and meeting the high demand for water, in the state. This indicates that the same strategy will attain success in Melbourne, Australia and solve water problems.
Problems
On the problems in adoption of this strategy is that decline of water levels for rivers and reservoirs may affect the performance of the drainage system in a negative way. This will occur since the drainage system will not have water being transported, and consequently, crops may dry due to lack of water. Another problem is that heavy rainfall may lead to destruction of the constructed ditches, which are used for water transport. This may compromise the ability of the system to ensure effective transportation of water occurs. Moreover, the strategy demands that a personnel be outsourced who will be monitoring data from crop factors and climate and feed this data to the irrigation control program in order to trigger an irrigation event.
List of References
Hao, S 2006, Irrigation System. Web.
Michelsen, A 2009, Evaluation of Irrigation Efficiency Strategies for far West Texas: Feasibility, Water Savings and Cost Considerations. Web.
Sharma, V, & Irmak, S 2012, ‘mapping Spatially Interpolated Precipitation, Reference Evapotranspiration, Actual Crop Evapotranspiration, And Net Irrigation Requirements In Nebraska: Part Ii. Actual Crop Evapotranspiration And Net Irrigation Requirements’, Transactions Of The ASABE, 55, 3, pp. 923-936. Web.