i) I will enter USGS gaging station number

ii) Is USGS web server alive or down ?

i) I will ENTER my flow data (daily/hourly)

ii) I will UPLOAD my flow data (daily/hourly)

iii) HOURLY version - USGS Hourly Flow Database

iv) I will ENTER my flow data (monthly) for QQ plot

The prototype version of the Web-based hydrograph separation system was developed,
and is still available from https://engineering.purdue.edu/~kjlim/iSep. No change since Aug. 2002.


New hydrograph separation modules were added to the WHAT system.
- one parameter digital filter method (filter parameter) - same algorithm used in BFLOW filter - in SWAT Homepage
- two parameter digital filter method (filter parameter and BFI_max)
WHAT system was extended to include GIS capabilities for WI, MN, OH, IL, MI, and SC - July 27, 2004.
- For other states, please use 2) I will enter USGS gaging station number



Flow statistics module was added to the WHAT system.


Click here to see the overview of the WHAT GIS system using two different digital filters used in the WHAT GIS system.


K.J. Lim, B.A. Engel, Z. Tang, J. Choi, K. Kim, S. Muthukrishnan, and D. Tripathy. 2005. Web GIS-based Hydrograph Analysis Tool, WHAT. JAWRA, 41(6): 1407-1416.