A linked water supply/water quality model of the New York City reservoir system was used to
evaluate the feasibility of modifying reservoir operations to reliably control turbidity in NYC's Catskill
System. In particular, the model was used to evaluate operating rules to meet turbidity and temperature
targets in diversions from Schoharie Reservoir to Esopus Creek, a Class A trout stream that conveys
Schoharie water downstream to Ashokan Reservoir. Schoharie Reservoir supplies up to 615 mgd of
water to the NYC system, and is a critical source of supply for the City. Additionally, Schoharie
diversions are required to maintain minimum flows in Esopus Creek and are critical to the health of the
trout fishery. However, discharges of occasionally turbid Schoharie water subsequent to storm events
may compromise the overall quality of NYC's unfiltered drinking water supply and may have a
potential negative impact on aquatic habitat and recreation in Esopus Creek.
The water supply model, OASIS (HydroLogics, Inc., Columbia, MD), simulates the routing of water
through the entire NYC reservoir system (including the Catskill, Delaware, and Croton systems and the
entire Delaware River basin). The model accounts for environmental constraints and physical
limitations as well as operating rules for water supply reliability. A linear programming module
optimizes flow routing operations under user-defined targets and constraints. OASIS is linked to a two-dimensional
hydrodynamic water quality model for Schoharie Reservoir, CE-QUAL-W2 (Upstate
Freshwater Institute, Syracuse, New York), which predicts daily turbidity and temperature profiles in the
reservoir. Various operating rules, making use of the turbidity and temperature profiles, storage, time
of year, and inflow forecasts, are programmed into OASIS which then models the effects on water
supply reliability. Such operating rules include reducing discharges from Schoharie during elevated
turbidity conditions, reducing drawdown, and reducing withdrawals during early summer to preserve
the cold water bank for release to Esopus Creek in late summer. This paper provides a review of the
linked model and demonstrates how it can be used to develop reservoir operating rules that balance
water supply reliability, drinking water quality, and environmental release objectives. Includes abstract only.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 210 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 1 |
| Published : | 06/01/2006 |
