7. Using Python to Access Hydrologic Data from Web Services

Learning Objectives

1. Discover and access data from major hydrologic data sources
2. Create reproducible data visualizations
3. Write and execute computer code to automate difficult and repetitive data related tasks
4. Manipulate data and transform it across file systems, flat files, databases, programming languages, etc.
5. Retrieve and use data from Web services

Computer and Data Requirements

1. You will need Python and PyCharm installed for this assignment. You should have them already from previous assignments.
2. You will need the following Python modules installed: suds, pandas, and matplotlib. You can install these using the PyCharm package manager.
3. The data needed for this assignment are available via a WaterOneFlow web service. You can access the web service at: http://hydroportal.cuahsi.org/nwisuv/cuahsi_1_1.asmx Links to an external site.

Task

Explore the data available from the USGS Unit Values WaterOneFlow web service, retrieve a time series of 15-minute discharge values, calculate daily summarized data, and then visualize your outputs.  Use the following steps to complete the assignment:

1. Modify the Python script presented in class to retrieve a time series of 15-minute discharge data from an active, realtime USGS monitoring site of your choosing for the past 3 months (August 2015 – Present).  Use the USGS Unit Values web service listed above.  The Network code for this service is “NWISUV”.  The SiteCode for a USGS gage would be it’s USGS identifier (e.g., “10109000” for the gage in the Logan River above State Dam Near Logan, UT).
2. Write Python code to calculate the daily min, max and average discharge values for each day within the time period of data you retrieve from the 15-minute instantaneous values.
3. Using the skills that you have learned with Matplotlib, write Python code to generate a plot of the resulting summarized flows.  Your plot should have three lines, one for min, max, and average flows. You may choose to add the 15-minute values to your plot as well. Add a legend to your plot to distinguish the lines.  Make sure you include appropriate x- and y-axis labels and a title for your plot.

Deliverable

Submit the following to complete this assignment:

1. A one-page briefing that includes
   1. A description of the USGS gage site that you chose.
   2. A statement of your methodology for calculating the daily summary flows (minimum, maximum, and average) from the 15-minute values
   3. A statement of your methodology for creating the figure
   4. A description of the characteristics of flow at the site you chose. Was any interesting behavior observed?
2. An appendix with your figure with an appropriate caption.
3. An appendix with a listing of your Python code.
4. Your Python code (a separate .py file) submitted to Canvas as a separate upload so that your instructor can run your code.

A PDF of this assignment for printing purposes is available here: Assignment7.pdf Download Assignment7.pdf