Category: Irrigation

Introduction

The essay is a critical examination of advantages and disadvantages of dewatering techniques. The various techniques analyzed in the essay are general sump pumping, open dewatering, well points, deep well and submersible, ground freezing and electro osmosis. Dewatering typically refers to the act of removing water from solid materials or even soils. This is done mainly by “classification, centrifugation, filtration or similar solid-liquid separation processes” (Turovskiĭ & Mathai, 2006). In construction, it refers to removing or draining water either found under the ground or on earth surface from place of construction, river beds or mine shafts among other related works. All the mentioned techniques of dewatering do have advantages as well as disadvantages.

General sump pumping

Generally speaking sump pumping has been used by individuals to remove water from their houses or compounds. The pumps are less noisy; for instance submersible sump pump have been shown to be quieter when under operation. Additionally, there is a provision in which it turns on automatically provided that water has reached a certain level. On the same note, the way the pumps have been build ensures that when there is need for repairing then it does not require a lot of labor and also it is less expensive. The automation mechanism makes the technique more reliable.

The method works well in tight and soils having a fine grain as well as course and boulder deposits. However, the problem with this technique is that it only pumps water that is not solid. Another draw back of using general sump pumping technique is that the amount of water removed entirely depends on how reliable is the pump as well as the supply of power. This can be a problem when the later is in short supply. Sump dewatering is also characterized by backfilling that hinders construction works as it compromises the sub-grade substrate.

Open dewatering

As suggested by Powers, 1992 it is applicable in situations where one wishes to bring down level of groundwater table where the soils are cohesive and have lower permeability. The technique can be temporary installed, work well in toughest environment especially when gravel, sand and other particles are present. It also works well in greater depths. Similarly, it has been noted that open dewatering is the simplest methods of dewatering since it entails placing of a suction hose and the water is then removed. It takes little space and due to the ability to temporary installs them and being easy to remove it can serve several areas or locations. The major limitation of this method is the lack of ability to be used in hard strata. Similarly construction work cannot go on till the ground is completely dry and stable.

Well points

The technique helps control level of water in an aquifer. The advantage of this technique rests mostly in its ability to cut cost. Additionally it is suitable for removing water from shallow excavations approximately 6.5 m in soils that are stratified (Powers, 1992). This can also be seen as a disadvantage especially when the excavations are deep than 7.0 m. However, the provision of installing it in stages can address this problem. Additionally the ability of the technique to perform better in a wide range of soils is an advantage. Well points also make it possible to have “a much thicker width free from seepage forces” (Turovskiĭ & Mathai, 2006). One major disadvantage of this technique is that it is somewhat expensive when compared to sump pumping method.

Deep well and submersible

Using this technique to remove water has been shown to be effective as well as having a higher capacity. It is suitable in water that has no particles. Additionally the maintenance of the equipment used is chap and easy. Finally it works well in deep wells > 80fts or more. The major limitations or drawbacks of this technique are; impellers as well as diffuser cannot stand the presence of particles for instance sand (Powers, 1992). Similarly, when the water being removed contains gases it may lock the pump and finally the pump can malfunction if the well runs dry.

Ground freezing

According to Harris, 1995 the technique uses heat transfer to stabilize the ground; soil water is turned into ice. The advantages include; can be applied in any type of soils as well as varying groundwater conditions, has no known long term consequences on subsurface environment. Additionally, the technique can be easily and completely removed, suitable in controlling water movement from one region to another only in temporal basis and it can completely cut of water. Lastly it is the most effective method in situations where other techniques such as pumping cannot be attained. The ability to completely cut off water makes it possible for work to continue without worrying about seepage. One major disadvantage of this technique is that it uses a lot of energy in trying to maintain the frozen condition.

Electro osmosis

Unlike mechanical dewatering techniques, electro osmosis dewatering has several advantages which include; it can successfully remove water from sludge characterized by very fine particles as well as materials deemed to be gelatinous. The method is also very economical since it utilizes minimal power and yield tremendous results. In areas where the water being removed contains pathogens and bad smell, then the technique can help come up with high quality biomass (Yoshida, 1993). Similarly the equipment used in the process of dewatering is easy to use and maintain. Although it has the mentioned advantages, the technique cannot completely remove water in sludge since a discontinuous of a liquid state cut electric flow hence stopping electro-osmosis process.

References

Harris, J. (1995). Ground Freezing in Practice. London: Thomas Telford Services Ltd.

Powers, J. (1992). Construction dewatering: new methods and applications. New York City: John Wiley & Sons.

Turovskiĭ, I. & Mathai, P. (2006). Dewatering: Wastewater sludge processing. Hoboken, New Jersey: John Wiley & Sons.

Yoshida, H. (1993). “Practical aspects of dewatering enhanced by electro-osmosis: Drying Technology” An International Journal, 11(4): 784-814.

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.

Irrigation involves supplementing rainwater or substituting it with water from other sources. Irrigation systems are established in order to ensure that plants do not utilise a lot of unnecessary water. Scarcity of water in many places makes it necessary to conserve it and avoid over-usage where possible.

Implementation of an irrigation system ensures that water is used sparingly and also acts as a natural weed control method (Sudha, 2007). This essay will focus on irrigation system strategy as a method of conserving water.

To understand how an irrigation system works, it is important to look at the different types of irrigation systems available. The first type of irrigation is known as ditch irrigation. This method was used to carry out irrigation before modern irrigation methods were discovered. It involves planting crops in trenches.

The watering process is conducted by constructing canals between the crops or plants. Water is transferred from the large ditch by the use of siphon tubes. It is then directed to the canals. It is an irrigation system that was widely used in the United States but it has been taken over by other modern irrigation systems.

The second type of irrigation is referred to as terraced irrigation. This type of irrigation requires a lot of labor. This type of irrigation involves digging numerous steps anchored by walls on the sides. Planting is done on the flat pieces of land. As each individual plot is watered, water flows down in all the steps. This type of irrigation makes it possible for steep lands to produce crops.

The third common form of irrigation is known as drip irrigation. Among all irrigation systems, this is the one that uses water most efficiently. Water collects at the bottom of plants through a dripping motion. Proper installation of this irrigation system ensures that water is not lost through runoff and evaporation (Yakubov, 2012).

The fourth type of irrigation is sprinkler irrigation. It is usually based on sprays and overhead sprinklers which are fixed on risers. The system can also be buried underground where the sprinklers only rise due to pressure. It is commonly used in parks and golf courses. The pipes used can either be fixed permanently or mobile (Warrick, 1983).

However, in some situations they are fixed in a manner that allows them to move freely. The operations of the watering system are either automatic or partially automatic. The following diagram shows how sprinkler irrigation takes place.

Generally, the purpose of irrigation is to ensure that crops get enough water for growth. This is mostly applied in places where plants or crops are likely not to get enough rainwater. However, to maintain this balance excess water is used, causing some of it to become deep percolation.

Deep percolation is water that passes vertically through the water zone to deeper soil layers below the root zone of the crop. The water can also become surface runoff which is the water that does not enter the soil and flows off a lower portion of the field. Both deep percolation and surface runoff are not used by the crops.

The amount of water that is applied during irrigation depends on certain factors among them the type of the crop, variability and type of soil, field size, labor needs and the method used in applying the irrigation water to crops (Stine & Gerba, 2005). The irrigation system is expected to save up to 60 % of water that would have gone to waste had there been no irrigation.

Since water is a scarce commodity and not all farmers can afford irrigation, some farming methods can be used as alternatives. The first alternative to irrigation is crop rotation. This allows the soil to regain its fertility and also gives it a chance to retain enough water for the crops.

The second alternative that can be used instead of irrigation is no-till farming. This farming method allows farmers to till more acres since the method is not labor intensive. No-till farming is advantageous to farmers in that when the stubble from the crops harvested in the previous year is left in the fields, the soil collects the moisture from crops grown in the previous season.

In addition, the stubble creates a canopy that prevents the soil from the formation of a hard layer that inhibits penetration of moisture. These are some of the alternative methods that can be used instead of irrigation (Mishra & Kannan, 2012).

In order to understand how much water is saved by the application of irrigation systems, it is important to look at different irrigation methods and the methods they use to transport water from the source to the crops in the field. The efficiency with which various irrigation methods save water is based on the differences that define them.

This is because the physical qualities of various irrigation methods differ. The effectiveness of surface irrigation methods in saving water is determined by making a comparison between the amount of applied irrigation water and the amount of water required to refill the root zone of the crop.

When the amount of water that gets into the soil is more than the amount required to restore the soil moisture, the excess water becomes deep percolation. Surface runoff occurs when water is applied at a high speed that does not give it a chance to get into the soil completely.

Establishment of irrigation systems is an important way of boosting agricultural production. Irrigation has therefore been applied in different parts of the world. One of the countries where it has been widely used is China. The Chinese irrigation schemes are famous for their good design apart from being on a large scale.

The Chinese perfected the use of primitive techniques in irrigating their land, something that contributed towards the formation of fundamental farmland irrigation systems that were able to irrigate the land.

The systems have been a great success in China since they have boosted agricultural productivity remarkably. As a result, they have been spread throughout the country. Most of the irrigation schemes serve the functions they were designed for.

The cost of an irrigation system is determined by various factors and considerations. As a result, there is no standard cost. The first factor that determines the cost of an irrigation system is the type of irrigation method used. Different irrigation methods have different requirements with their unique costs.

There are also fixed operational costs which include taxes, insurance, depreciation and interests. Other factors that are factored in during the process of costing include pumping costs, since the water must be pumped from its source to the field (Hussein, 2000).

However, based on the above mentioned factors, it is possible to estimate the cost of the entire irrigation strategy. It is important to have an estimate of the total money required in order to look for it before the project starts. The whole project is estimated to cost $ 20,000.

Irrigation efficiency is determined when records of how crops use water during irrigation are studied. Accurate results are obtained when the studies are conducted for a certain period of time. These methods indicate that the various irrigation types save a lot of water that normally goes to waste.

During the implementation of the irrigation system, some problems are encountered. The first problem associated with irrigation is salinisation. This is the process through which salts build up in the soil until they become toxic for the survival of plants. Presence of salt in the soil is associated with decreased osmotic potential, which prevents the soil from absorbing water (Bordovsky & Eduardo, 2000).

Salty soil increases the solute concentration of the soil compared with that of the root, thus plants are unable to absorb water. In most cases, salinisation occurs when excess water is applied.

Water used in irrigation is usually rich in salts which are absorbed as it moves through the land. Rainwater is also rich in salts whose concentration is low in water. Instead of increasing productivity, salinisation leads to reduced productivity (Irrigation Systems, 2012).

Another problem that occurs as a result of irrigation is waterlogging. This occurs mostly in soils whose drainage is poor, making it difficult for water to penetrate into the soil. It also takes place in topographies that do not allow proper drainage to take place.

Water used in irrigation ultimately causes the water table to go up. Rise in the water table causes waterlogging of the soil. This fills air spaces present in the soil with water, leading to suffocation of plant roots due to lack of oxygen. In order to reduce salinisation and waterlogging, it is important to improve irrigation efficiency.

An irrigation system is one of the best strategies that should be implemented in Kingston suburb which is in Melbourne, Australia. As discussed earlier, water is a scarce resource that should be preserved and used sparingly. Kingston neighborhood is a suburb where many middle class people live.

Implementing an irrigation strategy is of great importance to this population since they can engage in productive agricultural activities. In addition, an irrigation strategy would ensure that they conserve the little water they have thus avoiding water shortages.

Another important reason why this strategy should be implemented in Kingston is that there are different types of irrigation patterns. Some of them do not require a lot of money and expertise knowledge to implement. This implies that the residents can work on the irrigation strategy successfully without incurring huge expenses or looking for experts to assist them. In addition, they can choose an irrigation strategy that suits their needs.

Through an irrigation strategy, the residents of Kingston suburb will be able get rid of some diseases associated with stagnant water. This is because the water that collects in trenches and shallow depressions will be harnessed and used for irrigation. Generally, it is a good strategy that will benefit the residents of the suburb once implemented.

Reference List

Bordovsky, J. & Eduardo, S., 2000, “Economic Evaluation of Texas High Plains Cotton Irrigated by LEPA and Subsurface Drip.” Texas Journal of Agriculture and Natural Resources, 15: 76-73.

Hussein, A. 2000, Principles of environmental economics. New York: Routledge. Irrigation Systems 2012. Web.

Mishra, A. & Kannan, K., 2012, Improving Existing Practices of Water Delivery in a Run-of-the-River Based Canal System for Better Water Use Efficiency. Irrigation and Drainange, 5: 30–340.

Stine, S. & Gerba, C., 2005, Application of microbial risk assessment to the development of standards for enteric pathogens in water used to irrigate fresh produce: Journal of food protection, 68: 913-918.

Sudha V., 2007, Reservoir Operation Management through Optimization and Deficit Irrigation. Irrigation and Drainage System, 55: 20-100.

Warrick, A.1983, Interrelationships of Irrigation Terms. Journal of Irrigation and Drainage Engineering, 109: 317-332.

Yakubov, M., 2012, Assessing Irrigation Performance from the Farmers’ Perspective: A Qualitative study, Irrigation and Drainage, 10: 316–329.

There can be no project without taking risks. Each idea presupposes dealing with certain difficulties, and implementing these ideas is doubtlessly a challenge.

Despite the fact that both Hydroelectric Development and Irrigation Scheme offer a fair assessment of the possible risks and provide a detailed account of the challenges that one can face in the course of putting these projects to practice, one of the two projects is definitely superior, which calls for conducting comparison between the two case studies.

To start with, each of the projects identifies the risks which can be faced rather accurately. It is essential that each of them offers a table in which every possible risky occasion is considered.

However, it seems that the Irrigation Scheme offers a better identification of risks, since it not only provides a detailed account of every risk involved, but also splits the risks into categories according to their types and, thus, provides a better estimation of the threats which the project can possibly face.

The same can be said about the way the case studies quantify the risks. One must give credit to both case studies, since they offer a detailed description of the risks assessment and provide the risks percentage.

Nevertheless, it is worth mentioning that the Hydroelectric Development project offers the percentage of all possible costs in the summary of the hydro cost estimate, which makes it more comprehensible than the Irrigation Scheme.

However, speaking of which case study is easier to understand, one has to admit that in the given case, numbers and rates are enough only to give the general idea of the situation which the authors of the projects face. For a better understanding of the situation specifics, hoverer, a more explicit description of the factors, the risks and the circumstances is required, which the Irrigation Scheme project provides in a much better way.

In addition, it is worth mentioning that a good assessment presupposes considering the costs which the project can possibly spend. While Hydroelectric Development suggests only the table of the probable risks, Irrigation Scheme offers the information concerning the financial resources which the project will probably need. Such data as “Expected cost $20 million, standard deviation $3 million” is essential to fully realize the scale of risks.

Finally, speaking of the risk assessment, one must mention that the Hydroelectric Development takes the winning position again, because it takes into account not only the inside factors, but also the outside ones, such as weather conditions. In contrast to Hydroelectric Development, Irrigation Scheme provides only the information concerning the risks which come from within the project.

Therefore, it can be considered that the Hydroelectric Development project is by far more compelling and offers much better analysis of the risk factors. In addition, the assessment offered by the above-mentioned project covers not only the major issues, but also the details, which altogether makes it much more plausible than the alternative.

Once all the probable risks are properly evaluated, a project can be considered a success, which, as one can assume, is the case with the Hydroelectric Development.

Although it is not clear yet which of the projects will prove more efficient, and the opinion in the given paper is based solely on the facts offered by the case studies, it can still be assumed that the Hydroelectric Development project is bound to take the first prize in the contest for a better risk evaluation.