Hydrologic Conditions in Kansas, Water Year 2015

The U.S. Geological Survey, with federal, state and local partners, runs a long-term network of hydrologic monitoring sites in Kansas. In 2015 it included about 200 real-time streamgauges, 12 real-time reservoir-level stations and 30 groundwater wells. The data, checked through the year with regular measurements, help protect life and property and manage water for farms, industry, public supply, ecosystems and recreation. Each year's conditions are judged by comparing that water year (WY), the 12 months from October 1 to September 30, named for the year in which it ends, with the historical record.

Precipitation and drought

Kansas had been in drought early in the decade. Conditions improved with more rain in WY 2013 and held nearly steady in WY 2014, despite below-average precipitation, as the drought shifted from the western half of the state to the southwest and south-centre.

In WY 2015 most of Kansas got average or above-average precipitation, and May to July 2015 was the seventh-wettest such period in 121 years of state records. The west, southwest, north-centre and northeast were wetter than normal all year; the southeast and a diagonal band across the middle were at or slightly below normal.

Percent of normal (1981–2010) precipitation, water year 2015. National Oceanic and Atmospheric Administration.

At the start of the year about 17 percent of Kansas was in severe drought, 27 percent in moderate drought and 35 percent abnormally dry. By the end only about 4 percent was in moderate drought and 15 percent abnormally dry. The biggest change came in the south and southwest, where the drought had been worst; by year's end nearly all of that area was out of drought, and only the northwest, where precipitation was below normal, was still affected.

Streamflow and runoff

Monthly streamflow was mostly normal at the start of the year, but by April it was below normal, much below normal or at record lows in more than half the state. By May most of Kansas was normal or above, apart from parts of the northwest, and most of the south and east ended the year normal while other regions stayed low.

Monthly streamflow percentiles in September 2014, April 2015, May 2015 and September 2015. USGS.

Runoff, streamflow per unit of area, is a good indicator of a basin's precipitation and streamflow. Kansas runoff in WY 2015 was more than twice that of WY 2014, at the 59th percentile of runoff computed since 1901. It was normal at first except in parts of the west and south-centre; in the second quarter most of the state was below normal, with much-below-normal and record-low runoff in the western half; then third-quarter rains pushed runoff above and much above normal in the east and northeast, a pattern that held to the end of the year, when only the northwest and centre stayed below normal. Runoff does not follow precipitation alone: water soaking into the ground, lost to aquifers or held in reservoirs never leaves the basin, which is probably why above-normal precipitation in parts of the west produced less runoff.

Reservoirs

Many of the main federal reservoirs began the year at normal levels. Intense rain in May and June pushed 10 of the 12 USGS-monitored reservoirs above their conservation (multi-purpose) pools and partly into their flood-control pools, and nearly all released more water, raising annual streamflow downstream. By year's end five held less water than at the start, six more, and one the same.

Horsethief Reservoir, near Jetmore in the southwest where rain ended the drought, filled its conservation pool for the first time since it was completed in 2009: 34 percent full at the start of the year, 104 percent at the end of May, 83 percent at the end.

USGS lake-level stations in reservoirs, and streamgauges, water year 2015. USGS.

Three streams, west to east

• Arkansas River at Syracuse (western Kansas): normal flow in WY 2015, after four years below and much below normal; in WY 2013 the river stopped flowing for a short time, a first in 98 years of record.
• Saline River near Russell (central Kansas, where precipitation and runoff stayed low and drought persisted): mostly below normal since WY 2012, and still below normal in WY 2015 except in late April and mid-May.
• Kansas River at De Soto (eastern Kansas): mostly normal in WY 2015, except for above and much above normal flow from May to July.

Floods and record flows

In May and June 2015 several sites flooded, and two gauges with 30 or more years of record set peak flows. The Little Blue River at Hollenberg reached 59,000 cubic feet per second on May 7, the highest in 40 years of record, after intense rain, and the gauge downstream near Barnes reached 56,000 cubic feet per second on May 8, the highest in 57 years. Cumulative flow near Barnes stayed above the 75th percentile for the rest of the year.

Cumulative discharge at the Little Blue River near Barnes (drainage area 3,351 square miles, 57 years of record) in water year 2015, against the median, the 25th–75th percentile band, the lowest year (2006) and the highest (1993). USGS.

Summary

Drought ended for most of Kansas in WY 2015, leaving the smallest area affected since WY 2010. Despite high flows in May and June, many gauges ended the year below normal. The northwest and centre, with below-normal precipitation, stayed in drought with low streamflow; the rest of the state had normal to above-normal streamflow and runoff, and the west recovered from drought. Most monitored reservoirs filled their conservation pools, though five in northern Kansas ended the year with less water than they began with.

Sources

• Madison R. May, Summary of Hydrologic Conditions in Kansas, Water Year 2015, USGS Fact Sheet 2016–3015, March 2016. https://doi.org/10.3133/fs20163015
• The maps, graph and table are taken from the fact sheet's PDF; its drought charts and maps, from the National Drought Mitigation Center, are not reproduced here.
• The original dates the earlier severe drought to water years 2011–12 in one place and 2011–13 in another.