ABSTRACT
Surface
water is the greatest contributor to many water supplies in urbanized areas. Understanding
local water sources and seasonality is important in evaluating water resource
management, which is essential to ensure the sustainability of water supplies
to provide potable water. Here we describe the municipal water cycle of
Columbus, Ohio, USA, using δ18O, δD, and d-excess, and follow water
from precipitation through surface reservoirs to a residential tap between May
2010 and November 2011. We show that trends in water isotopic composition of
Ohio precipitation have a seasonal character with more negative values during
the winter months and more positive values during the summer months. The year
of 2011 was the wettest year on record in Central Ohio, with many months having
high d-excess values (>+15‰), suggestive of increased moisture recycling,
and possibly moisture introduced from more local sources. Tap waters
experienced little lag time in the managed system, having a residence time of
~2 months in the reservoirs. Tap waters and reservoir waters preserved the
isotopic signal of the precipitation, but the reservoir morphology also
influenced the water residence time, and hence, the isotopic relationship to
the precipitation. The reservoirs supplied by the Scioto River function like a
river system with a fast throughput of water. The other reservoirs display more
constant solute concentrations, longer flow-through times, and more lacustrine
qualities. This work provides a basic understanding of a regional water supply
system in Central Ohio and helps characterize the water flow in the system. These
data will provide useful baseline information for the future as urban
populations grow and the climate and hydrologic cycle changes.