Drought is generally defined as decreased precipitation resulting in a water shortage. These deficits can result in decreases in groundwater levels, causing drinking water shortages, or decreased agricultural production when lack of rainfall or limited irrigation water sources lead to reduced crop growth. Hydrological drought, or decreased flow in rivers and streams, is another way to identify regional water shortages.
The Spokane River depends on spring runoff from winter snowpack to sustain flows. At the end of March, the snow water equivalent, or the amount of liquid water stored in snowpack, for the Spokane River Basin was 105% of normal (based on 1981-2010 median). Relying on snowpack alone, Spokane could not predict drought conditions this year. Warmer spring temperatures are causing snow to melt early, leaving no water to replenish summer riverflow. That is why locally we cannot rely solely on precipitation to predict drought. To protect our river, we need to prioritize and respond to low river flows, especially when they occur in late spring or early summer. Status of the river should guide how we manage water resources in Spokane.
Map above shows the Spokane River Basin (HUC 170103) and snow water equivalent for each of the snow monitoring stations at the end of March 2021. As you can see, most stations had near or above normal amounts of water stored in snowpack, making it difficult to predict the drought conditions we are currently experiencing.
https://www.nrcs.usda.gov/wps/portal/wcc/home/quicklinks/imap
The river is warning us that water supplies are low, and we need to listen. Since the river is connected to our water supply, the SVRP aquifer, increased water consumption in the months of June through September also influences the severity of drought conditions in the river. Hydrologic drought creates poor conditions for fishing and boating and less cool water for native trout, which is especially detrimental in early summer for young fish. By using water wisely, as a community we can benefit summer river flow, ensuring healthy habitat for native fish and other wildlife; season-long fishing, floating, and kayaking; a place to cool off in the heat; and a beautiful, rushing river for everyone to enjoy.
This year exemplifies why we need to use river flow as an indicator of drought in order to better manage our water consumption. The graph above shows how average monthly flow this year (in orange) compares to the average monthly flow over the last 129 years (in blue). Flow rates in June were less than 50% of the normal and in July the average was one-third of the normal.
Data obtained from https://waterdata.usgs.gov/nwis/uv?site_no=12422500
The graph above shows the monthly average flow rate of the Spokane River, at the downtown USGS gauge (river mile 72.9), during the spring and summer months (April-September) in 2011, 2015, and 2021. If you compare river flow rates during a non-drought year like 2011 to drought years like 2015 or 2021, you can see how much lower river flow is during a drought.
Data obtained from https://waterdata.usgs.gov/nwis/uv?site_no=12422500
Read on to learn a little more about the different types of drought and how it can affect our community…
Spokane River in a drought
Photo taken at Sandifur Bridge on August 21, 2021, at 6pm. River flow was at 733 cubic feet per second.
There are many definitions and types of drought. The four most common classifications are meteorological drought, hydrological drought, agricultural drought, and socioeconomic drought.
· Meteorological drought is typically based on decreases in precipitation from the average or “normal” amount for a given time period
· Hydrological drought is a result of decreased rain or snow that leads to reduced flow in streams or rivers, falling lake or reservoir levels, and diminished groundwater supply
· Agricultural drought becomes evident when plant growth and crop production declines
· Socioeconomic drought occurs when the supply of economic goods/services (e.g., drinking water, crops, fish, or hydroelectricity) cannot meet demand because of shortages in water supply
Drought can cause many problems for the economy, society, and the environment. Here in Spokane County, this year’s drought could reduce wheat production or hay available for livestock; cause hydroelectricity shortages or power outages; increase possibility of dust storms or haboobs; and affect summer recreational activities like fishing, rafting, or kayaking. We are already seeing abnormally low flows and high temperatures in the Spokane River and several wildfires in the region resulting in poor air quality locally; drought contributes to all these conditions.
Photo credit: Tim Connor
References
Natural Resources Conservation Service. (2021, March 31). Western US SNOTEL Snow/Precipitation Update Report. United States Department of Agriculture. https://wcc.sc.egov.usda.gov/reports/UpdateReport.html?textReport=Western+US&textRptKey=14&textFormat=SNOTEL+Snow%2FPrecipitation+Update+Report&StateList=Select+a+State&RegionList=14&SpecialList=Select+a+Special+Report&MonthList=March&DayList=31&YearList=2021&FormatList=N0&OutputFormatList=HTML&textMonth=March&textDay=31&CompYearList=select+a+year
National Centers for Environmental Information. (2021). Did you know? Monitoring references: Definition of drought. https://www.ncdc.noaa.gov/monitoring-references/dyk/drought-definition
National Drought Mitigation Center. (n.d.). Types of drought. University of Nebraska School of Natural Resources. https://drought.unl.edu/Education/DroughtIn-depth/TypesofDrought.aspx
National Drought Mitigation Center. (2021). Washington: Historic impacts. University of Nebraska-Lincoln, United States Department of Agriculture, and National Oceanic and Atmospheric Administration. https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?WA