# Presentation: 796098

## Developing A Low Flow Impacts Database For 

***Advanced Hydrologic Prediction Service (AHPS) ***
***Forecast Points***
***A Riverine Reporting System for Drought Impacts***

**Cody Knutson****1****, Mark Svoboda****1****, Melissa Higgins****1**** **
**and Doug Kluck****2**** **
**/****1****National Drought Mitigation Center; ****2****National **
**Weather Service CRHQ/NOAA**

**Photo courtesy of Ken Dewey, HPRCC**

## Low Flow Project

- Partnership between NDMC and NWS Central Region Headquarters
- Collect low flow river impacts for NWS forecast sites
- Upper Mississippi (2004), North Platte (2005) and Upper Missouri (2006-in progress) River basins
- Collected information from 115 federal, state, local and private water experts
- 38 NWS AHPS forecast sites analyzed (04 & 05)

## Low Flow Project

- Electronic survey and phone follow ups conducted
- What were the experts asked?
- What are the impacts of low river levels and at what stage/flow do these impact occur?
- Is there a specific time of year when the impacts will occur?
- Which AHPS site (or sites) best reflect conditions at the locale?
- Are there any other factors that affect low flow impacts at the locale?

## Database Structure

| Flow (cfs) | Stage (ft) | Impacts | Timing/Other Considerations | Information Sources |
| --- | --- | --- | --- | --- |
| 2000  |  | Recreational activities such as boating may become difficult |  | DNR Trails and Waterways Division (2004) |
| 1400 |  | Hydropower facilities at Champion Dam and St. Cloud Dam will implement measures to adjust river flows as part of the Mississippi River System-Wide Low-Flow Management Plan |  | DNR System-Wide Low-Flow Management Plan (2004) |
|  | 974 | The St. Cloud Water Treatment Facility can meet a maximum pumping demand of 16 million gallons of water per day |  | Lisa Vollbrecht, St. Cloud Water Services Manager |
|  | 973.5 | The North Intake Structure for the St. Cloud Water Treatment Facility will not be able to draw water | February 2004 – low flows and ice buildup blocked the North Intake – the hydroelectric facility raised the pool depth for the intake to function |  |
|  | 970.5 | The St. Cloud Water Treatment Facility can meet a maximum pumping demand of 12 million gallons of water per day |  |  |
|  | 970 | The South Intake Structure for the St. Cloud Water Treatment Facility will not be able to draw water |  |  |

**Database Structure**

## Low Flow Project Key Findings

- Several potential impacts were identified:
- Loss of municipal, industrial, and agricultural water supplies
- Reduced recreational opportunities
- Hydropower and power generation losses
- Dredging to maintain navigation
- Fish and wildlife losses
- Activation of state and local drought response plans
- River basins have common and unique low flow vulnerabilities
- Local water authorities could not establish at what stage/flow impacts at some sites would occur...more research needed

## Low Flow Conclusions

**Developing a better understanding of low river**
**impacts at the local level will provide more**
**detailed information for water resources**
**planning applications at all levels of**
**government, as well as in advancing the**
**development of the AHPS system**

## Some Possible Future Uses In the National Weather Service

- Levels Graphically Represented on Forecasts (short and long term)
- Drought Prediction and Substantiation
- Listing Drought Impact Levels On Internet Pages (like flood levels)
- Other Ideas?

## A Future Use of the Impacts Database

**An example of a seven-day river forecast hydrograph with indicators of critical low flow and flood levels. The ****red line**** indicates the flood level.  The ****tan line**** indicates the critical low flow level at this forecast point. The ****blue line**** shows the current river level and the ****green line**** is the actual forecast.**

**A Future Use of the Impacts Database**

## A Future Use of the Impacts Database

**Figure 4. An example of a 90-day streamflow outlook for low water. The values along the x axis show the probability of reaching a particular flow (y axis). The brown zone at the bottom of the graph shows the critical level for this forecast point at which low water impacts begin to take effect. CS = conditional simulation; HS = historical simulation. **

**A Future Use of the Impacts Database**

## Reporting Critical Flood LevelsWe will be able to do the same for low flows

- 33.0  THE BUSINESS DISTRICT IN LASALLE FLOODS
- 31.0  FLOOD DAMAGE BEGINS IN OTTAWA
- 30.0  WATER OVERTOPS THE LASALLE WATER PUMPING STATION PIT
- 29.0  FLOODING BEGINS IN SECTIONS OF PERU
- 27.5  HENNEPIN LEVEE IS OVERTOPPED AT ROAD CROSSING
- 27.0  SOME BASEMENT FLOODING BEGINS TO LOW LYING RESIDENTS IN OTTAWA
- 21.0  LOW LYING AGRICULTURAL AREAS FROM 6 MILES UPSTREAM TO 12 MILES DOWNSTREAM ARE FLOODED
- 20.0  AGRICULTURAL AREAS IN LASALLE, SPRING VALLEY, AND PERU LOWLANDS ARE FLOODED
- 17.5  SOME FLOODING OF AGRICULTURAL LAND BEGINS

## Low Flow Categories and Historical Low Stages Similar to Flood Information

**Flood Categories (in feet)**	Major Flood Stage: 31	Moderate Flood Stage: 27	Flood Stage: 20	Action Stage: 19.5
**Top 5 Historical Crests**(1) 32.05 ft on 12/05/1982(2) 31.75 ft on 03/21/1979(3) 31.70 ft on 03/06/1985(4) 31.00 ft on 05/22/1943(5) 30.83 ft on 02/23/1997

## First Steps: North Central River Forecast Center’s New Page

**http://www.crh.noaa.gov/ncrfc/ahps/ESPMAPS/map/m10000.html**

## Slide 13

## Three Month Probability of Falling to Low Levels

## The End

- _[http://www.crh.noaa.gov/ncrfc/ahps/ESPMAPS/map/m10000.html](http://www.crh.noaa.gov/ncrfc/ahps/ESPMAPS/map/m10000.html)_
- _[http://www.nws.noaa.gov/climate/xmacis.php?wfo=eax](http://www.nws.noaa.gov/climate/xmacis.php?wfo=eax)_

## North Platte Basin

## Upper Mississippi Basin