Bersiap untuk bahaya banjir
'To Be or Not To Be' - Prepared for FloodsWritten by Jeremy Duensing & Jeff JohnsonApril 25, 2014
It’s safe to say that most of the country has experienced extremely volatile weather within the last few years. Research shows that weather patterns are, and will continue to be, increasingly volatile due to changing climate trends. Whether it’s dauntingly cold temperatures or unexpected heavy snowfall, it’s no longer a question of if severe weather will occur, but rather when, and when it will affect your assets.
The risk of floods are increasing as the climate becomes more volatile, and now more than ever, it is important to understand what led us to this point and how to stay ahead of flooding waters. Information is power, and preparation is key to protecting assets in an emergency situation.
Climate Change – Human vs. Natural Factors
The earth’s climate is influenced both by natural and human factors, with the impact of each still a hotly debated topic. Natural factors that cause climate variability influence the atmospheric circulation patterns. Seasonal ocean cycles like El Niño and La Niña create wetter or drier and colder or warmer patterns when the prevailing jet stream wind shifts locations.
The North Atlantic Oscillation is another naturally-occurring seasonal influence. The upper-level circulation pattern in the polar latitudes can produce abnormally warm and cold periods throughout North America depending on its location. Ocean temperature patterns, volcanoes, and the sun’s cycles can also influence the climate.
Deforestation, agriculture, and urbanization are several human factors that can influence climate change. When a city replaces a forest, the land’s temperature is raised due to increased heat absorption and retention while agriculture provides the opposite effect of cooling an area, especially when irrigated. Increased run-off from land-use changes more quickly fills streams and rivers.
Impacts of Climate Change
Communities, infrastructure, and governments are all at risk of negative impacts due to a changing climate. One of the most devastating results is the increase in the frequency of volatile weather events such as flooding. Scientists have taken note of a greater number of the more extreme weather occurrences in recent years. New research suggests that warming in the arctic region is resulting in a weaker temperature contrast that is slowing down the jet stream. This has led to slower moving weather systems or ones that have been persisting for longer periods of time over the same areas. Extreme weather tends to occur more often with these stalled weather systems.
In 2007, the Intergovernmental Panel on Climate Change (IPCC) concluded that intense rain events have become more frequent in the last 50 years. This, combined with increased run-off from land use changes, means more significant flash flood events can and will occur. In addition, as the oceans warm, scientists predict that the number of hurricanes, and potentially their intensity, could increase. Higher sea levels from warmer waters also can lead to greater storm surges.
According to the U.S. Geological Survey, flooding already costs the U.S. more than $7 billion in damages, killing more than 90 people annually. Increased flooding has potential to wreak even more havoc on dense populations, with 3,800 towns and cities in the flood plain.
From that, it’s not surprising that floods claimed more in terms of number of lives and property damage than any other type of natural disaster during the last century. By the end of the century, assuming no change in built infrastructure or values, a 2013 article in the Journal of Flood Risk Management projected an increase of approximately 30 percent in damages from flooding alone.
These trends in flooding frequency and severity are likely to continue, meaning federal state and local governing bodies and agencies must be prepared. An article in Nature found the recent emergence of a statistically significant positive trend in the risk of great floods is consistent with results from a climate model, and that model suggests that the trend will persist.
Public safety officials must arm themselves with accurate, real-time data that gives a complete picture of conditions they face in order to properly prepare for an increase in frequency and severity of floods. Improved visibility allows officials to make faster, more informed decisions based on aggregated data rather than estimating when a disaster will affect certain assets. Traditionally, several disparate sources were needed to gather information on the two key factors that determined flood conditions: flooding parameters and weather conditions. Today, software can integrate all dire information into a single source that provides a clear, real-time snapshot of the environment.
Flooding Parameters: What to Watch for
A clear understanding of the most critical parameters to monitor for a potential flood is essential: water level, tide prediction, and wave height. New technology gives asset managers the ability to set alert parameters and to be notified whenever one of these factors crosses a threshold that triggers a response.
Tide prediction: Tide predictions are based on the gravitational force of the moon and sun acting on large bodies of water at a given time. These are especially helpful when severe weather and rainfall are approaching, as the tide can significantly impact the severity of conditions. For example, a storm that hits at low tide may not require the same level of preparation and resources as a storm that arrives at high tide.
Water level: The measurement of a body of water’s level is an obvious factor when determining the likelihood of a flood, but quick access to accurate readings may be difficult. Plotting water level observations from thousands of ocean buoys and river gauges alongside other high-impact weather information such as radar and local storm reports, a public safety manager increases his or her situational awareness with a real-time, geographic representation of high-impact ocean tides and river depths.
In addition, hourly forecasts of ocean water levels give critical guidance on where large-scale weather patterns will have an impact on tide levels in the future. This pinpoints specific times of day where a normal tide may be higher than expected due to strong storms and winds.
Wave height: Not only should an official have the technology that indicates exactly when high tide will occur and its level, but he or she should also have an understanding of wave conditions during that time to better predict how communities and infrastructure may be impacted. High waves may have little impact if they are predicted to occur during low tide. These same high waves occurring during a higher than normal tide may have a much higher impact and will direct the size and type of response necessary.
Weather Forecasting is Essential
Current technologies can combine real-time data with accurate weather forecasting to give public safety officials an even more powerful tool for storm preparedness. Operators now have the ability to use a real-time map of water conditions that can also display hourly forecasts to achieve optimal awareness of when water levels, tides, and wave heights will coincide with high-impact weather.
The climate is changing, and with it the frequency and increasing severity of extreme weather events, including floods. Emergency managers must have a clear view of current circumstances in their territory, as well as an accurate understanding of how forecasted weather events will strengthen or mitigate the impact of severe weather. With an aggregated view of flooding parameters and integrated weather forecasts, resources can be mobilized more quickly, communities can receive more advanced warning, and managers can be better informed to protect people and infrastructure.
Jeremy Duensing is the transportation product manager at Schneider Electric based in Minneapolis, Minn. Duensing joined Schneider Electric in September 1998 and has worked in the weather department since he graduated from the University of Nebraska in Lincoln with a bachelor’s degree in meteorology. In addition to several years on the forecast desk, he has also started a forecast verification program and most recently has been involved in expanding weather products and services to the transportation community and is a member of the American Meteorological Society ITS/Surface Transportation Weather Committee.
Jeff Johnson has been with Schneider Electric for more than 30 years and currently serves as the company’s chief science officer. In addition, Johnson is a Certified Consulting Meteorologist, who’s certification illustrates the highest level of professionalism and overall knowledge of the science of meteorology.