Lake Level Changes in the Arid West


Summary

Many basins in the arid West today contain small lakes, but also contain shoreline deposits that indicate these lakes were once much larger. In this lab students explore the impact of changes in climate on the level of lakes in the Owens River system. These lakes, which were separated by bedrock sills and which were fed by runoff from the eastern flank of the Sierra Nevada mountains in California, were headed by Owens Lake. When Owens Lake filled to its maximum level, it overflowed into the China Lake Basin, which in turn overflowed into Searles Lake. During particularly wet periods in the geologic past Searles overflowed into Panamint Lake, which ultimately overflowed into Manly Lake in Death Valley. Students use the STELLA modeling software to see what combinations of runoff and evaporation might have led to Pleistocene lake level oscillations.

Learning Goals

The Owens Lake Chain exercise has the following purposes:
  • To teach the importance of boundary conditions. Each of the lakes in the chain is limited in the volume, depth, and area it can attain by the presence of a spillway in its drainage basin. Students have to learn how to deal with these boundary conditions by using conditional statements.
  • To convey the concept of response time and what it is dependent on.
  • To experiment with oscillatory behavior.

Context for Use

This activity was developed for a class introducing dynamical systems modeling to upper level undergraduate students.

Description and Teaching Materials

lake_modeling_lab_2003.pdf (Acrobat (PDF) 12kB Jun7 05)
Owens_Lake_Chain_Model_Image.pdf (Acrobat (PDF) 142kB Jun7 05)
owens_lake_chain_v7.STM ( 280kB Jun7 05)
owens_chain.f90 ( 4kB Jun7 05)
hypsometry_dat.xls (Excel 59kB Jun7 05)

Teaching Notes and Tips

Instructor Notes (Acrobat (PDF) 12kB Apr10 06)
Note: All the math for the model is laid out fully in the Menking and Anderson chapter listed in the References and Resources section.

Assessment

lake_modeling_lab_answer_key.pdf (Acrobat (PDF) 222kB Jun7 05)
assignment_assessment__6.pdf (Acrobat (PDF) 5kB Jun7 05)

References and Resources

Menking, K.M. and R.S. Anderson (1995). A Model of Runoff, Evaporation, and Overspill in the Owens River System of Lakes, Eastern California (Acrobat (PDF) 900kB Jun7 05). Department of Earth Sciences and Institute of Tectonics, University of California, Santa Cruz.