ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

The Reason We are Seeing 100-year Rain, Wind and Seismic Events

Updated on July 13, 2013

What is a 50-year Rain Storm? What is a 100-year Storm?

California Civil Engineer here. When a 50-year storm hits, it means there is a 2% chance of that event in any given year. There is a 1% chance for a 100-year event to occur this year.

These events are predicted based upon records of past events. All large cities and counties have their own records of rain fall. Some cities have 50 years worth of data. Some of the longest record keeping goes back more than 100 years. These rainfall levels are usually recorded at airports and public engineering departments. It is possible for two 50-year rain events to dump water on the same city in the same year. Statistically, it is a reasonable series of events; it is not statistically improbable.

Each city keeps its own data and produces its own tables to predict rainfall. Most cities’ new underground storm water systems are designed to move a 50-year rain event. Other municipalities have some common problems: older cities have very old pipes underground. Many of these are too small. Another common problem is lack of elevation available to create slope to move water quickly. Increased velocity moves more water.

If two large events arrive together, more flooding results. The first downpour soaks the soil. The second event, with reduced ground absorption, produces more runoff.

For example, the annual rainfall, and the maximum event that has a 2% chance of occurring in Riyadh, Saudi Arabia, is much smaller than for Seattle, Washington. A 100-year event in Riyadh is likely a 10-year event in Seattle. Is this beginning to make sense?

When someone says there is a "record" rain storm, or "the biggest in 20 years", it doesn't really mean much without knowing other factors.


Rains in Excess of Natural and Man-made Systems Create Floods

Wind is Measured and Predicted Same as Rain

Wind predictions, similarly, are predicted based upon historical events. Airports famously have excellent wind data. Additionally, a wind design may be based upon locally collected wind data, and not on national tables provided by professional organizations such as the American Society of Civil Engineers (ASCE) and the International Building Code (IBC).

The phrase, “a fifty year event” is professional engineering jargon. To have major events occur suddenly together is nothing to alarm the people.

Why are Recent Rain and Wind Events Different than in Past Decades?

This is what should receive attention: These events are only infrequent in the places where they are happening. Rain events in the proportions being reported in news channels as 100-year events in New York are much more common in other regions and other latitudes. Events change according to geography. For example, mountains cause clouds to rise as they pass over. This condenses the moisture and creates rain and snow. This is why California is green and Nevada is desert chaparral. Clouds moving in from the ocean dump on the western side, and carry very little to the east of the Sierra Nevadas. A common rain storm in a California foothill town might be very rare in a Nevada city east of the mountain range.

Rainfall levels also change according to the latitude & longitude of a location such as a city. Today, the earth is tilting off the axis it has been on for thousands of years. The latitude and longitude of locations is changing. Because of this relocation of cities within the lat-long matrix, weather events are going to change.

What is the Engineering Community Doing?

Within the engineering community, this natural phenomenon is largely going unnoticed. However, there are some engineers who recognize that seismic, wind, and rain/flood events are becoming slightly less predictable. I think the major organizations will begin to discuss this in the next decade. However, it is unlikely that the ASCE or the IBC will address this before then. For these leading design procedure codifiers to institute new processes of design, some substantial data, theory, and remedies will need to be proposed in the engineering community.

Comments

    0 of 8192 characters used
    Post Comment

    • profile image

      Ausseye 

      6 years ago

      To the MAN: To weather this storm I am referring people to your hub, a hum dinger. Great to hear a reasonable voice in a country that created the Al Doom of climate…….a wealth of useful information. I see this hub as a sunny disposition opposed to a DARK sky…..some real information is appreciated. Keep the Hurricane blowing. A sensible discussion is noted here, good on you mate. Cheers Ausseye.

    • BWD316 profile image

      Brian Dooling 

      7 years ago from Connecticut

      great hub! and great explanation of 100 year storm events. So weird i posted a few hubs about the extreme weather in the northeast about four hours before you posted this hub. voted up!

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)