Read Me for Mass Balance Data:

These files contain data regarding a daily (midnight-to-midnight) mass 
balance for an infiltration basin that collects stormwater runoff. The inputs 
to the system are: water flowing through a culvert and precipitation falling 
into the basin. The outputs from the system are: infiltration into the ground
and evapotranspiration (ET).

VolChange = Precipitation + Inflow - Infiltration - ET
Infiltration = Precipitation + Inflow - VolChange - ET

Each file is named with the corresponding water year (WY). A water year runs
from 1 October - 30 September; for example water year 2012 (WY12) is 
1 October 2011 - 30 September 2012.

Each file has twelve columns of data. 

The first column indicates the water day (1 through 365), where water day 1
 = October 1. 
 
The second column indicates the total volume of precipitation that fell in the
infiltration basin, in cubic feet.

The third column contains the daily volume of ET in cubic feet. Each day, the
total ET was estimated as the minimum of daily recorded precipitation and PET
measured at a local CIMIS station (http://www.cimis.water.ca.gov/)

The fourth column contains the daily volume of water flowing into the infiltration
basin through the culvert (calculated independently). 

The fith column conatins change in volume of water in the infiltration basin
from one day to the next, in cubic feel. The volume of water in the infiltration
basin is calculated using a measurement of pressure in the basin (converted 
to water depth) and a detailed survey of the field site that allows us to convert
water depth to volume in the basin.

The sixth column indicates the average wetted area of the infiltration basin on
each day. This is also calculated using survey data. Note: the area measurement
is pegged at 25,000 ft^2 at the lowest value, because this is approximately
the wetted area at which we first start recording water in the basin with our
pressure gauges.

The seventh column contains a solution to the mass balance, solving for volume
infiltration flux (cubic feet).

The eighth column contains the daily average infiltration rate (ft/day) based
on the infiltration flux and wetted area.