MCD has its eye on water

By Mike Ekberg, MCD manager for water resources monitoring and analysis

Did you know MCD tracks precipitation, groundwater levels, and flow in rivers and streams?

This information helps MCD and its partner agencies with flood forecasting, groundwater quantity monitoring, and understanding water movement into and out of the Great Miami River Watershed.

Here’s what we tracked in 2016 and what we’ve seen in 2017.

Water in 2016

  • Precipitation for the year was right around 37 inches or about 2.5 trillion gallons of water.
    • Average annual precipitation for the Miami Valley is about 43 inches.
  • Precipitation was below average eight of 12 months in 2016.
    • August was a notable exception with nearly 6 inches of rain. The average for that month is a little more than 3 inches.
  • Runoff from the Great Miami River Watershed into the Ohio River was about 12 inches or 823 billion gallons of water. Runoff includes water from rainfall and groundwater water that seeps into the river.
    • Average annual runoff is about 15 inches.
  • Water levels in the buried valley aquifer began the year near average at most observation wells. They declined to below-average levels during the summer and then returned to average levels in the fall.
  • Water recharge to Miami Valley aquifers averaged a little more than 6 inches or about 411 billion gallons.
    • Average annual recharge for the watershed is around 8 inches. Despite the lower average for 2016, the region has an abundance of groundwater.

What are we seeing in 2017?

We’re not even halfway through the year, and precipitation and runoff are trending above average. At the end of May, MCD had recorded nine high water events this year, which is above average for the entire year. MCD recorded only five high water events during all of 2016.

MCD defines a high water event as a time when:

  • Any single dam goes into storage, meaning the elevation of the water upstream of the dam exceeds the top of the dam’s conduit.
  • Or the river at any of our cities reaches an “action stage” as defined by the MCD Emergency Action Plan, such as closing a floodgate.

All of the dams except Huffman Dam have stored floodwaters at least once this year:

  • Germantown Dam – 7 storage events
  • Englewood Dam – 9 storage events
  • Lockington Dam – 1 storage event
  • Taylorsville Dam – 1 storage event

According to the National Oceanic and Atmospheric Administration’s Ohio River Forecast Center, there’s an equal chance of above- or below-average precipitation for the next three months. Beyond that, it’s anyone’s guess.

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2015 in Review: A Wet Year

The year 2015 has come to a close and before we get too far into 2016, I thought it might be interesting to review the year from a hydrologic perspective given all the recent attention to El Niño and the December 27-30 high water event on the Great Miami River and its tributaries.

The Great Miami River Watershed received an average of 45.26 inches of precipitation in 2015. The 30- year average annual precipitation is 41.18 inches, so 2015 was well above average.

Precipitation was significantly above average during the months of April, June, July, and December. February, May, and September were significantly drier than normal. No record highs or lows were set in 2015.

Above-average precipitation in 2015 led to above average runoff. Runoff is the amount of water carried out of a drainage area by streams. Runoff for the Great Miami River was measured at 18.37 inches for the year, which is 5.34 inches above average.

At least one Miami Conservancy District dam stored water on 12 different occasions in 2015. The average number of annual storage events for the MCD flood protection system is eight. The largest storage event was the December 27–30 event when all five of MCD’s dams were storing floodwaters. Together the dams stored 14.2 billion gallons of water behind the dams. This event ranked as the 32nd largest storage event in MCD history.

All in all, 2015 was a continuation of a rising trend in precipitation for our region. The chart below shows how the 30-year average annual precipitation for the Great Miami River has changed since 1985, and has been rising sharply since the 1990s. What can we expect if this trend continues? The answer is more rain, more runoff, and more high-water events.

30-year precip chart