2024-018 - Emergency Operations Plan

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City of Santa Ana Emergency Operations Plan Part I Basic Plan deficiency in precipitation, usually over several seasons, which proves insufficient to meet the demand that people place on the water supply. The U.S. Drought Monitor is a weekly map of drought conditions that is jointly produced by the National Drought Mitigation Center at the University of Nebraska -Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration and the current map can be located at www.droughtmoiiitor.unl.edu. U.S. Drought Monitor maps provide a consolidated depiction of national drought conditions based on a combination of drought indicators and field reports. The assessment can be broken out by state or region. The Drought Monitor summary map identifies general drought areas, labeling droughts by intensity, with DI being the least intense and D4 being the most intense. Drought intensity categories are based on five key indicators, numerous supplementary indicators including drought impacts, and local reports from more than 350 expert observers around the country. The drought severity classification table shows the ranges for each indicator for each dryness level: Drought Severity Classification Ranges Category I Descrlp0on Possible impacts Palmer Drought cPc Soil usG weekly Smndardbed I ay..nre anon and IIMdx Moisture Model SOeamtmw Preclp0atlon index eoneanm n o gtd ' �PercerHimE) )Percen0les) ISPQ IMb.W mend. 1 ' ( IPam.rrdb.l i I �a.�e eb eA.9nr. srm.re�arvn.u.n.'ns i � ',,. pp�ny ." 9melnol_P. P.m.., W_,..1 4.010 �19 21-30 2130 -0510-07 ', 21-30 Do Dry 'p m n.upl..rr. r,9.m9.aa. e.kda (wwp. rolNh r.w..r.d �Sorra da 9 b wp P una urearre, � I i 01 '+Moeerate Dmbgm. !b xal.r.naM1e9as -z.om-za n-zD n-zo adm 12 11-20 dawbpYrq.rnnnanl', w4nlarymlawu � i w str.[Y ns nod-..d i D2 Severe 1 omugbt �Gnpwpasluia by.. awy: wel.,,n.nav>• � ., ..urr..eamn..rpn..e 3.9 -&10 Historical Drought Events — The State of California averages 23 inches of precipitation (snowfall in the mountains and rainfall in other areas) per year and Orange County averages about half that with 12-14 inches per year. Approximately 75% of precipitation falls between November and March and approximately 50% falls in the months of December, January and February. Significantly reduced precipitation in these fall and winter months is the primary cause of drought. Since actual precipitation varies widely from year to year, drought is usually a cumulative effect of several dry years. California has experienced five significant multi -year drought periods in the last century. With the progressive effects of climate change altering precipitation patterns and causing wanner temperatures, combined with the constantly growing population of Southern California consuming more and more of the available water supply, water shortages may occur more often or more severely in future years. 1929-1934 - This drought occurred during a decade -long dry period associated with the "Dust Bowl" conditions that spanned the western United States in the early 1930's. 1931 was the second driest year in recorded state history. Because of the annual variability in precipitation levels, precipitation is often measured in three-year periods to provide more of an average. Of the top 10 driest three-year periods on record, five occurred between the years 1922 and 1933 (1922-24, 1923-25, 1924-26, 1929-31 and 1931-33). Though this drought was severe by hydrological measures, its impact was limited by the much smaller population, agriculture and urban development levels of the state at that time period. 103