Importance of Rainfall Data and Analysis in Civil Engineering; and Rain Gauges PDF

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In your opinion, what do you think is the importance of rainfall data and analysis in civil engineering? What is the main purpose of installing rain gauges.? What are the basic rules for the installation of rain gauges? Describe the different types of instruments used to measure precipitation and pr...

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Optional, Karl Christian A. Hydrology Assignment #2 1. In your opinion, what do you think is the importance of rainfall data and analysis in civil engineering? - Precipitation is most commonly termed rain and includes rain, drizzle, hail and snow. The type of precipitation (when observed) is recorded along with the amount of precipitation. Rainfall includes all forms of water particles, whether liquid (for example, rain or drizzle) or solid (hail or snow), that fall from clouds and reaches the ground. It is important for civil engineers to know rainfall data since their projects will be affected by water. In every civil engineering project, one of the fundamental duties of the design/ engineering team is to make sure that there is no issue with the site. 2. What is the main purpose of installing rain gauges.? What are the basic rules for the installation of rain gauges? - A rain gauge (also known as a udometer, pluviometer, or an ombrometer, or a cup) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over an area in a predefined period of time. A rain gauge (also known as a udometer, pluviometer, or an ombrometer, or a cup) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over an area in a predefined period of time. 3. Describe the different types of instruments used to measure precipitation and provide pictures/diagrams of each type. a) Standard Rain Gauge - standard gauges measure precipitation at or near the ground, and are observed at least once a day. The sizes of the gauges are made big enough to collect more than the average one-day or maximum 1-2-hour precipitation which differs according to various climatic conditions.

b) Automated Rain Gauge - There are electronic rain gauges that measures rain fall, and are also self-emptying and frost proof. The basic idea is the rain collector’s measuring spoon being automatically tipped and emptied when the pre-adjusted water weight has been reached.

c) Weather Radar - A weather radar is a type of radar used to locate precipitation, calculate its motion, estimate its type (rain, snow, hail, etc.), and forecast its future position and intensity.

d) Weather Satellite - is a type of satellite that is primarily used to monitor the weather and climate of the Earth. These meteorological satellites, however, see more than clouds and cloud systems. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc., are other types of environmental information collected using weather satellites.

4. Name, describe and distinguish the main sources of error in measurements of rainfall. - INSTRUMENT ERRORS - A well-adjusted siphon rain gauge has an accuracy of 0.2 mm for precipitation of up to 20 mm per hour. A tipping bucket rain gauge has an accuracy of 0.5 mm for precipitation of up to 20 mm per hour, but may have errors of up to 3% for stronger precipitation. In Japan, the minimum observation unit is 0.5 mm, and precipitation less than this amount is not measured. Errors increase with higher precipitation intensity, and exceed 3% for precipitation of more than 150 mm per hour. - ERRORS FROM WETTING - If the inner wall of the receptacle and the funnel surface are not sufficiently water-repellent, rainwater

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adheres to them and does not reach the storage bottle or the tipping bucket, thereby causing errors. Residual rainwater in the storage bottle or storage vessel of a storage rain gauge causes measurement errors. If rainwater is measured repeatedly with the measuring glass, the residual water for each measurement also causes measurement errors. Dirt, dust and other contaminants adhering to the inside of the storage tank in a siphon rain gauge absorb water, resulting in residual water that causes errors. If the inside of the siphon is soiled, it will not operate properly and will result in errors. Water remaining in a tipping bucket after tipping also causes errors. ERRORS FROM EVAPORATION - Water remaining in the tipping bucket and subsequently evaporating causes errors. If a heater attached to a tipping bucket rain gauge to melt snow heats the gauge by +5 to +10°C, weak precipitation or snowfall may evaporate, thereby causing errors. ERRORS FROM THE LACK OF A WINDSHIELD - As the amount of weak precipitation entering the receptacle is reduced by wind, the lack of a windshield causes significant errors. ERRORS RELATED TO TIPPING BUCKET RAIN GAUGES IN HEAVY RAIN - In tipping bucket rain gauges, rainwater enters the bucket even when it in a tipping state, and water that is drained without being measured causes errors. These errors increase with heavier precipitation, and the amount measured becomes less than the actual amount. Water equivalent to precipitation of 50 mm was dripped from a standard rainfall simulator vessel with different precipitation intensities, and the number of resulting tips was found to decrease almost linearly with increasing precipitation intensity. The error exceeded the allowable level of 3% when the intensity was more than 150 mm/h, causing the precipitation amount measured to be less than the actual amount. Review and study about linear regression. Show the computation of Example #2 using linear regression in calculating for the slope m=0.8045....