The TOPMODEL algorithm requires a rainfall times series ($\Delta t$ = 15 min) for each subwatershed.

First attempt involved using radar data - not much luck.

Next, a network of recording rain gauges was set up in the summer of 2004. Each gauge records the time each one-hundredth inch of rain collects in its tipping bucket mechanism. The initial network had six gauges. The network was expanded to 13 gauges in 2005, and 15 gauges for the 2006 and 2007 seasons.