What’s ahead for our region’s weather?

By Mike Ekberg, Manager for Water Resources Monitoring and Analysis

In my August 1, blogpost, “Climate Change: Is It Real?” we noted that our climate is always changing. Some people want to debate the cause, but that’s not nearly as important as planning for the changes that are expected.

A warming trend will amplify the extremes in our region’s climate, according to the Third National Climate Assessment. We can expect more intense summer heat waves, more droughts, and more floods.

More rain when we don’t need it and less rain when we do
The Third National Climate Assessment says here’s what we can expect over the next 35 years:

  • Annual average temperature in our region is expected to increase as much as 4.9 degrees Fahrenheit.
  • Winter and spring precipitation is expected to increase 10-20 percent.
    • We’ll see less snow and more rain.
    • Storms are likely to be stronger, increasing the chance of flooding.
  • Summer rainfall is expected to drop 8 percent, increasing the chance of droughts.
    • Summer droughts can increase water demands on utilities for lawn irrigation.
    • More frequent summer droughts can increase water demand for crop irrigation.

The Miami Valley will need to cope with intense winter and spring rain events when human water demand is low. Likewise, we’ll need to cope with hotter – and sometimes drier – summers when human water demand is high.

Making changes now key to coping in the future
How can our region successfully cope with these challenges?

Planning and wise infrastructure investment is the key. Here are some steps communities in our region can take to prepare for a warmer future.

  • Minimize paved surfaces to reduce flash flooding and streambank erosion.
  • Encourage infiltration areas such as pervious pavement, rain gardens, and drainage swales to reduce urban runoff.
  • Install flood warning systems in areas prone to flash flooding.

    rain garden

    Rain gardens reduce storm water runoff by using the rain water on your property, allowing it to soak into the ground and recharge the aquifer.

  • Invest in more water storage to meet summer demands.
  • Manage summer water demand through regulations, rate structures, or consumer incentives.
  • Use the most efficient irrigation technologies to reduce summer water demand.
  • Provide cooling shelters for people who do not have access to air conditioning during summer heat waves.

The time to act is now
Taking steps now is the key to preparing for a changing world. Our region is fortunate to have sufficient water resources and should be able to weather the forecasted changes if we manage those resources well. If we don’t prepare now, we’ll be playing catch up later, and that could prove to be costly.

 

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

Winter 2016 and “The Mother of all El Niños”

El Niño is getting a lot of media attention these days being blamed for floods, famine, and the spread of diseases. This year’s El Niño is shaping up to be one of the stronger, if not the strongest, El Niño in history. In fact, it’s drawing comparisons to the 1997 El Niño event, which is the strongest El Niño on record and sometimes called “The Mother of all El Niños.”

According to the National Oceanic and Atmospheric Administration (NOAA), the current El Niño event in the Pacific Ocean is expected to peak in December, but the impacts of El Niño are expected to last well into the spring of 2016. These impacts are likely to influence weather in our region.

El Nino comparison

Comparison of 1997 El Niño (left) and 2015 El Niño

When it comes to Earth’s climate, weather phenomena happening in faraway places can sometimes have dramatic impacts locally. El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific Ocean. The image above shows areas of the Pacific Ocean with above-normal water temperatures colored in red in August of the 1997 El Niño event and August of 2015.

When El Niño occurs, very warm waters in the Pacific Ocean pump more moisture into the atmosphere. This impacts and changes the direction of major wind currents, steering weather systems across the United States. In other words, the typical storm paths in the United States are shifted. Typically, El Niño shifts storm tracks south during the winter months resulting in increased precipitation across the southern tier of the United States. At the same time, El Niño tends to bring warmer-than-normal temperatures to Alaska, Canada, and the northern tier of the United States. 

2016 3 month precipitation outlook

2016 3-month precipitation outlook

So what El Niño effects can our region expect
to see for the upcoming winter and spring?  According to NOAA’s climate prediction
center
, our region is likely to experience a mild winter temperature-wise with below-normal precipitation. The image on the right shows areas of the United States expected to have above-normal precipitation in green and
below-normal precipitation in brown over the next three months. Most of Ohio is colored in brown. The outlook for spring is similar, with near-normal temperatures and below-normal precipitation.

Is this forecast a sure bet? It isn’t. The Earth’s climate systems are extremely complex, and El Niño is only one of many factors influencing our weather. The temperature and precipitation outcomes we experience this winter are a result of a multitude of complex interactions among the Earth’s weather systems. We can only wait and see!

Region’s water levels more stable than other parts of the U.S.

By Mike Ekberg, MCD water resources manager

Stories about droughts, water shortages, and aquifers drying up are in the news with regularity these days, especially in places throughout the western United States.

What are the chances that our aquifer could run dry? Are the water levels in the Great Miami River Watershed and its buried valley aquifer increasing, declining or staying the same?

According to the measurements taken by MCD over the last 30 years, the water supplies in the Great Miami River (GMR) Watershed are in what’s called a steady state. That means the amount of water that flows into and out of the watershed – the 4,000 square miles of land that drain to the Great Miami River – is relatively constant over the last 30 years.

2014 Great Miami River Watershed precipitation totals

2014 Great Miami River Watershed precipitation totals

In 2014, the Great Miami River Watershed received 39.05 inches of rain and snowmelt (inflows) – which matches the long-term average. That amount of water equals 2.7 trillion gallons of water.

Water leaving the region through evaporation and plant uptake (outflows) averages about 26 inches or nearly 1.8 trillion gallons.

On average, another 900 billion gallons of water flows into the Great Miami River through runoff each year. Runoff is water that flows over the land (overland flows), runs through soils (interflow) and into the aquifers (groundwater flow).

That’s 2.7 million gallons into the watershed and another 2.7 million gallons out of the watershed.

Groundwater levels in aquifer

Graph shows seasonal fluctuations in the depth to groundwater. Over the last 30 years, there is no upward or downward trend.

There are fluctuations in water levels year to year, but over the long term, precipitation and runoff balance each other out, leaving the total amount of water stored in the Great Miami River Watershed essentially the same.

Another factor in water usage is human use. The Ohio Department of Natural Resources says people use about 124 billion gallons of water per year, mostly for public water supply, industry, and cooling water for power generation. Most of that water returns to the Great Miami River Watershed through municipal sewer and industrial wastewater treatment plants. Of the 124 billion gallons of water used by people, MCD estimates only about 23 billion gallons of water is actually consumed or removed from the watershed before it reaches the Great Miami River. Although 23 billion gallons of water sounds like a huge quantity, it’s only a small amount when compared with the 2.7 trillion gallons that enter and exit the watershed each year.

While our water levels are steady today, that’s no guarantee for the future. Changing weather patterns and increasing water uses by people are unknown. That’s why it’s critical to track water over time and why MCD measures precipitation and river flows throughout the watershed using a network of gages.

Keeping an eye on water levels is vital to detecting trends so that policies and programs can safeguard our water supplies.