U.S. Department of the Interior

U.S. Geological Survey

USGS Open-File Report 2005–1233

November 2005

Submersed Aquatic Vegetation Modeling Output Online

By Yao Yin, Jim Rogala, John Sullivan, and Jason Rohweder

The ability to predict the distribution of submersed aquatic 

vegetation in the Upper Mississippi River on the basis of physical or chemical variables is useful to resource managers. Wildlife 

managers have a keen interest in advanced estimates of food 

quantity such as American wildcelery (Vallisneria americana) 

population status to give out more informed advisories to hunters before the fall hunting season. Predictions for distribution 

of submerged aquatic vegetation beds can potentially increase 

hunter observance of voluntary avoidance zones where foraging 

birds are left alone to feed undisturbed. In years when submersed 

aquatic vegetation is predicted to be scarce in important wildlife 

habitats, managers can get the message out to hunters well before 

the hunting season (Jim Nissen, Upper Mississippi River National 

Wildlife and Fish Refuge, La Crosse District Manager, La Crosse, 

Wisconsin, personal communication).

We developed a statistical model to predict the probability of occurrence of submersed aquatic vegetation in Pool 8 of 

the Upper Mississippi River on the basis of a few hydrological, 

physical, and geomorphic variables <http://www.umesc.usgs.gov/

management/dss/sub_veg_model.html>. Our model takes into 

consideration flow velocity, wind fetch, bathymetry, growing-season daily water level, and light extinction coefficient in the river 

(fig. 1) and calculates the probability of submersed aquatic vegetation existence in Pool 8 in individual 5- x 5-m grid cells. The 

model was calibrated using the data collected in 1998 (516 sites), 

1999 (595 sites), and 2000 (649 sites) using a stratified random 

sampling protocol (Yin and others, 2000b). To validate the model, 

we chose the data from the Long Term Resource Monitoring 

Program (LTRMP) transect sampling in backwater areas (Rogers and Owens 1995; Yin and others, 2000a) and ran the model 

for each 5- x 5-m grid cell in every growing season from 1991 to 

2001. We tallied all the cells and came up with an annual average 

percent frequency of submersed aquatic vegetation occurrence 

and compared the results with actual LTRMP survey data (fig. 2). 

Both a paired Student’s test (P = 0.4620) and a Wilcoxon’s twosample test (P = 0.4738) did not contradict our null hypothesis 

that the model prediction and the sampling data are statistically the same. We have not found an effective statistical test to 

compare model-predicted spatial pattern with aerial photography 

geographic information, but we are satisfied with the model’s outcome on the basis of visual inspection (fig. 3).

A unique feature about this model is that a prediction can be 

made by the end of June each year; therefore, providing wildlife 

managers an assessment of current year vegetation growth condition 3 to 4 months ahead of the arrival of migrating waterfowl 

that feed on submersed aquatic vegetation. We are working with 

the LTRMP partnership to create a mechanism so that model predictions (fig. 4) <http://www.umesc.usgs.gov/management/dss/

sub_veg_model.html> can be updated annually and the results 

posted on the LTRMP Web site. Our model underestimated 

the prevalence of vegetation from 2001 to 2004. We speculate 

that the summer water level reduction conducted in 2001 and 

2002 triggered vegetation responses that are outside the model’s 

domain. Future enhancement of the model will incorporate the 

summer water level drawdown effects as well as the effects of 

growth conditions in previous years.

Figure 1. A conceptual expression of the submersed aquatic vegetation 

model.

Figure 2. Surveyed and predicted percent frequency of occurrence 

of submersed aquatic vegetation distribution in the transect sampling 

backwaters of Pool 8 of the Upper Mississippi River. Survey data were 

collected using a transect protocol (Yin et al. 2000b). Original data 

reported percent frequency on the basis of individual backwaters. The 

survey data used in the figure are the pooled means of all the backwaters on the basis of their respective acreages. LTRMP = Long Term 

Resource Monitoring Program. 
USGS Open-File Report 2005–1233

Surveyed Predicted

Pool 8

Figure 3. Surveyed (left) and predicted (right) distributions of submersed aquatic vegetation distribution in 

Pool 8 of the Upper Mississippi River in 1989. The survey 

data were from the land cover/land use geographic 

information created by the U.S. Geological Survey Upper 

Midwest Environmental Sciences Center on the basis of 

interpretation of aerial photography of 1989.

References

Rogers, S J., and Owens, T.W., 1995, Long Term Resource Monitoring Program procedures: Vegetation monitoring: National 

Biological Service, Environmental Management Technical 

Center, Onalaska, Wisconsin, July 1995, LTRMP 95–P002–3, 

10 p., Appendixes A–E

Yin, Y., Langrehr, H., Nelson, J., Blackburn, T., Cook, T., and 

Winkelman, J., 2000a, 1998 annual status report: Status and 

trend of submersed and floating-leaved aquatic vegetation in 

thirty-two backwaters in Pools 4, 8, 13, and 26 and La Grange 

Pool of the Upper Mississippi River System: U.S. Geological Survey Upper Midwest Environmental Science Center, 

La Crosse, Wisconsin, June 2000, LTRMP 2000–P002, 19 p., 

Appendixes A–B, (NTIS #PB2000–107875).

Yin. Y., Winkelman, J.S., and Langrehr H.A., 2000b, Long Term 

Resource Monitoring Program procedures: Aquatic vegetation 

monitoring: U.S.Geological Survey Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin, April 2000, 

LTRMP 95–P002–7, 8 p., Appendixes A–C.

Figure 4. Annual updates of predicted and surveyed status of submersed aquatic vegetation of percent frequency of submersed aquatic 

vegetation in Pool 8 of the Upper Mississippi River. LTRMP = Long Term 

Resource Monitoring Program.

For more information, please contact:

Yao Yin1, Jim Rogala2, and Jason Rohweder3

USGS Upper Midwest Environmental Science Center

2630 Fanta Reed Road

La Crosse, WI 54603

John Sullivan4

Wisconsin Department of Natural Resources

3550 Mormon Coulee Reed

La Crosse, WI 54601

Tel: 1(608)-781-6350

E-mail: 1yyin@usgs.gov

This report is a product of 

the Long Term Resource 

Monitoring Program.