Unit 5.2: Links between Land Cover and Stream Discharge

Introduction

The first part of this Unit focuses on a classroom discussion and activity on scaling. The discussion links the tree-level water balance of Unit 5.1 with the assumptions necessary to apply environmental sensor data to water balance calculations on a catchment or regional scale. Then, in the second part you will use a model to simulate management decisions for water resources. In this unit, you will:

• use basic methodologies to scale single point measurements up to the spatial scales of interest
• list challenges to scaling water balance components
• discuss how to overcome or work around those challenges to produce usable estimates
• apply acquired water cycling knowledge to data-driven water budgeting for societal and environmental needs

Unit 5.2: Links between Land Cover and Stream Discharge

Part 1 - Scaling

Pre-class

• Read the following: Goulden, M.L., Bales, R.C. (2014): Mountain runoff vulnerability to increased evapotranspiration with vegetation expansion. Proceedings of the National Academy of Sciences. 111 (39). DOI: 10.1073/pnas.1319316111.

Lecture Discussion

• We will discuss the pre-class reading (Goulden and Bales, 2014) and then discuss how scaling up, moving from point measurement to a basin-scale average, is important to link land cover and stream discharge.

Interpolation Activity

• This activity provides the structure for a classroom discussion on scaling. You will be shown how to interpolate from point precipitation measurement to areal averages, which will be followed by class discussion on scaling water balance calculations.

Homework

• Based on the class activity, a homework assignment is designed for you to average temperatures over a basin and determine whether precipitation falls as snow or rain.
• 5.2.1 Homework - Interpolation Worksheet (Microsoft Word 2007 (.docx) 284kB Dec23 16)
• 5.2.1 Homework - Interpolation Map (Acrobat (PDF) 17kB Oct12 16)

Part 2 - Spatial Modeling

In-class

SimWater - Mountains to Valley Activity

• SimWater is an activity that directly connects environmental and societal systems by simulating water management decisions at regional scales to meet environmental standards and societal goals. In Sections 1 and 2, you will apply your knowledge of spatial scaling and forest water use to extrapolate a surface water budget covering the Sierra Nevada headwaters of the Kings River to downstream populations in the Central Valley. You will then make data-driven land and water allocation decisions for multiple users in Section 3. Finally in Section 4, you will reflect on the activity and its broader implications by answering a series of exploratory questions and designing your land allocations on a map.
• Downloadable materials:
• SimWater Activity Packet (Acrobat (PDF) 669kB Mar20 17)
• Double-sided printing recommended
• Includes activity questions (8 pages) and 2 maps for exercise (2 pages)
• Map 1 contains a satellite image of the region. You should use this for extrapolating precipitation and forest water use in Sections 1 and 2.
• Map 2 is the same map extent as Map 1 but with the satellite image removed. This map should be used for Section 4, Question 12, when you map allocations.
• SimWater Allocation Spreadsheet (Excel 2007 (.xlsx) 13kB Mar20 17)
• Required companion Excel spreadsheet for Section 3, Questions 6 and 7. Instructions are included within the spreadsheet.
• Questions 6 and 7 each have their own section in the spreadsheet; cells for Question 7 are below the cells for Question 6. It is essential that you use the correct cells to answer each question.
• Only certain cells should be filled in; these cells are listed in the spreadsheet. Many cells in the sheet are automatically calculated and should not be altered.

• Finish incomplete sections of SimWater - Mountains to Valley activity. Turn in Activity Packet including maps when complete.

Additional Resources

• Bales, R. C., N. P. Molotch, T. H. Painter, M. D. Dettinger, R. Rice, and J. Dozier (2006), Mountain hydrology of the western United States, Water Resour. Res., 42, W08432, doi:10.1029/2005WR004387.
• Hunsaker, Carolyn T., Thomas W. Whitaker, and Roger C. Bales, 2012. Snowmelt runoff and water yield along elevation and temperature gradients in California's southern Sierra Nevada. Journal of the American Water Resources Association (JAWRA) 48(4): 667-678 doi: 10.1111/j.1752-1688.2012.0064.x
• Lui, F., Hunsaker, C.T., Bales, R.B. Controls of streamflow generation in small catchments across the snow-rain transition in the southern Sierra Nevada, California. Hydrological Processes p. 1959, vol. 27, (2013). Published, doi:10.1002/hyp.9304.
• Tague, C., and H. Peng (2013), The sensitivity of forest water use to the timing of precipitation and snowmelt recharge in the California Sierra: Implications for a warming climate, J. Geophys. Res. Biogeosci., 118, 875–887, doi:10.1002/jgrg.20073.