Overview of DEP Climate Change Integrated Modeling Project: Present Activity and Future Goals Watershed Science and Technical Conference West Point, New York September 14-15, 2009 Donald C. Pierson, Elliot M. Schneiderman, Mark S. Zion, David Lounsbury, and Donald Kent Bureau of Water Supply, New York City Department of Environmental Protection Hampus Markensten Upstate Freshwater Institute Allan Frei, Aavudai Anandhi, and Adao H. Matonse Institute for Sustainable Cities, City University of New York New York City Department of Environmental Protection Bureau of Water Supply Water Quality

Effects of Climate Change on the New York City Water Supply Climate Change is happening and will continue to occur. But we don’t know what the effects will be on: –The Quantity of Water Stored in the Water Supply –The Quality of Water Stored in the Reservoir System. Speculation is easy. Projections of changes are difficult, and are inherently uncertain. The purpose of this project is to move from speculation to projection.

GCM - Emission Scenario Current Conditions Scenario 65 Year into Future Scenario 100 Year into Future Scenario ECHAM-A1B ECHAM-A2“““ ECHAM-B1“““ GISS-A1B GISS-A2“““ GISS-B1“““ NCAR-A1B NCAR-A2“““ GCM/Emission Scenario data obtained from IPCC AR4 (2007) For each GCM/Emission Scenario, precipitation and air temperature are compared in control vs. future periods to derive monthly delta change factors. Climate Change Scenarios Delta Change Method Applied for 8 GCM/Emission Scenarios

GCM - Emission Scenario Current Conditions Scenario 65 Year into Future Scenario 100 Year into Future Scenario ECHAM-A1B °C+ 4.1 °C ECHAM-A2“+ 2.1 °C+ 4.3 °C ECHAM-B1“+ 1.8 °C+ 2.8 °C GISS-A1B °C+ 2.7 °C GISS-A2“+ 2.1 °C+ 3.4 °C GISS-B1“+ 1.3 °C+ 1.7 °C NCAR-A1B °C+ 3.5 °C NCAR-A2“+ 3.0 °C+ 4.8 °C GCM/Emission Scenario data obtained from IPCC AR4 (2007) For each GCM/Emission Scenario, precipitation and air temperature are compared in control vs. future periods to derive monthly delta change factors. Climate Change Scenarios Change in Mean Annual Air Temperature (°C)

GCM - Emission Scenario Current Conditions Scenario 65 Year into Future Scenario 100 Year into Future Scenario ECHAM-A1B % % ECHAM-A2“+ 9.1 %+ 8.9 % ECHAM-B1“+ 4.6 % % GISS-A1B % % GISS-A2“ % % GISS-B1“+ 9.5 % % NCAR-A1B %+ 6.3 % NCAR-A2“+ 6.0 % % GCM/Emission Scenario data obtained from IPCC AR4 (2007) For each GCM/Emission Scenario, precipitation and air temperature are compared in control vs. future periods to derive monthly delta change factors. Climate Change Scenarios Percent Change in Mean Annual Precipitation

GCM Derived Changes in Air Temperature and Precipitation and Watershed Model Derived Projections of Stream flow and Snowpack Sum of Delaware and Catskill System Watersheds 100 Year Forward Scenarios Mean Air Temperature ( o C) Based on 8 GCM/Emission Scenarios. Upper and lower bars are max and min of these. Box is the range of the remaining 6 scenarios. Bar within box is the median. Line shows baseline run. Mean Precipitation (cm/day) Mean Snowpack (cm) Mean Streamflow (cm/day) min max median 87.5 %tile 12.5 %tile

Start With Speculation

Air Temperature Magnitude Seasonality Precipitation Magnitude Intensity Timing Other Climate Data Solar Radiation Humidity Wind Potential Climate Change Effects on NYC Water Supply Climate Forcing

Hydro-thermal Effects Increased Water Temperature Reduced Ice Cover Longer Period of Thermal Stratification Changes in Reservoir Water level and Residence Time Air Temperature Magnitude Seasonality Hydrology Effects Increased Evapotranspiration Increased Precipitation Changes in Winter Precipitation, Snow Accumulation, and Timing of Snowmelt Changes in Antecedent Conditions Changes in Partitioning Between Sub- surface and Surface Runoff Changes in the Amount and Seasonality of Stream Flow Precipitation Magnitude Intensity Timing Other Climate Data Solar Radiation Humidity Wind Potential Climate Change Effects on NYC Water Supply Hydrology and Hydrodynamics

Hydro-thermal Effects Increased Water Temperature Reduced Ice Cover Longer Period of Thermal Stratification Changes in Reservoir Water level and Residence Time Air Temperature Magnitude Seasonality Hydrology Effects Increased Evapotranspiration Increased Precipitation Changes in Winter Precipitation, Snow Accumulation, and Timing of Snowmelt Changes in Antecedent Conditions Changes in Partitioning Between Sub- surface and Surface Runoff Changes in the Amount and Seasonality of Stream Flow Precipitation Magnitude Intensity Timing Other Climate Data Solar Radiation Humidity Wind Potential Climate Change Effects on NYC Water Supply Turbidity Turbidity Loading Effects Changes in the Frequency and Magnitude of Storm Events Changes in runoff:rainfall response Changes in Stream Channel Erosion Changes in Landscape Erosion Reservoir Turbidity Changes in the Frequency and Magnitude of Turbidity Inputs Changes in the Transport of Turbidity Due to Changes in Hydrodynamics Changes in Reservoir Operations Changes in Alum Use

Hydro-thermal Effects Increased Water Temperature Reduced Ice Cover Longer Period of Thermal Stratification Changes in Reservoir Water level and Residence Time Air Temperature Magnitude Seasonality Hydrology Effects Increased Evapotranspiration Increased Precipitation Changes in Winter Precipitation, Snow Accumulation, and Timing of Snowmelt Changes in Antecedent Conditions Changes in Partitioning Between Sub- surface and Surface Runoff Changes in the Amount and Seasonality of Stream Flow Precipitation Magnitude Intensity Timing Other Climate Data Solar Radiation Humidity Wind Potential Climate Change Effects on NYC Water Supply Eutrophication Nutrient Loading Effects Changes in the Frequency and Magnitude of Storm Events Changes in the Timing of Nutrient Loading Changes in Proportion of Surface Runoff Changes in Watershed Biogeochemistry Reservoir Trophic Status Changes in the Timing and Magnitude of Nutrient Inputs Changes in the Nutrient Availability Due to Changes in Stratification and Mixing Changes Phytoplankton Growth and Succession Due to Changes in Water Temperature and Light Extinction Changes in Hypolimnetic Oxygen and Nutrients

How to Make Projections

Integrated Modeling System

Watershed Models (GWLF-VSA, SWAT) Models Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Flows WQ Loads Watershed Models

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure Watershed and Reservoir Models Time Series –Historical Reservoir Operations

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations System Performance - Storage - Demand - Spills Watershed, Reservoir and System Models Results Flows System -Operating Rules -Demand

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Analysis of Watershed Management and Eutrophication Flows System -Operating Rules -Demand System Performance - Storage - Demand - Spills

Turbidity -Freq / Magnitude -Alum Decisions Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Climate Change (Delta Change, SDM,RCM) Climate Change Analysis – Phase I Flows System -Operating Rules -Demand System Performance - Storage - Demand - Spills Demand Projections System Infrastructure Operating Rules

Produce preliminary results in 18 months System Indicators of Water Quantity Upstream reservoir simulations Schoharie – effects on turbidity Cannonsville – effects on eutrophication Use existing models Develop preliminary model coupling to OASIS GCM data and simple downscaling CCIMP Phase I Watershed Model GWLF Water Quantity System Indicators Reservoir Models 1D (Eutrophication) 2D (Turbidity) System Operation Model OASIS Climate Data Historical GCM Predictions Simulated Reservoir Operations Turbidity System Indicators Eutrophication System Indicators Historical Reservoir Operations

Phase I Study Areas Quantity – Focus on West-Of-Hudson watersheds and reservoirs Location Map NY State NY City Turbidity – Focus on Schoharie Reservoir Eutrophication – Focus on Cannonsville Reservoir A. Anandhi et al. Future climate projections of NYC watershed: GCM selection and downscaling. A.Matonse et al. Climate change impacts on water availability in NYC water supply M. Zion et al. Potential Impacts of Climate Change on Water Quality in New York City Water Supply System H. Markensten et al. Climate Change Effects on Phytoplankton Composition in Cannonsville Reservoir Results Presented Here

Continuation of Phase I Improved Downscaling Expanded reservoir simulations Catskill System – effects on turbidity Delaware System – effects on eutrophication Expanded system operation modeling More explicit accounting of EOH and Delaware River Basin Explicit Feedback between Water Quality and Operation – Use of OST CCIMP Phase II Watershed Model Expanded in scope and greater testing GWLF SWAT Concepts Reservoir Models 1D (Eutrophication) 2D (Turbidity) Expanded in scope and greater testing Climate Data Historical GCM Predictions Improved Downscaling Turbidity System Indicators Eutrophication System Indicators Additional Tasks Watershed erosion sediment transport modeling Forest Modeling Explicit modeling of watershed biogeochemistry Model evaluation for climate sensitivity What model processes are most sensitive to Climate Change? Are these processes adequately represented in models? Forest Model Water Quantity System Indicators System Operation Model OASIS Simulated Reservoir Operations Optimization for future climate

Summary DEP’s system of watershed, reservoir and system operation models are valuable tools to project potential climate change effects on the NYC Water Supply, and to define the climate mediated processes that will be of greatest importance An Initial phase of analysis is nearing completion and results will be presented in the remainder of this session Future analysis will make use of improved climate data sets and improved models. New modeling of watershed erosion and forest processes will be undertaken Phase I analysis, while a valuable initial step, and the best estimate we can make at this time, can not be used to make definitive climate change predictions Modeling improvements and enhancements to improve climate change projections will lead to improvements in our other modeling missions such as evaluation of watershed management programs and management of reservoir turbidity

Aknowledgements DEP for funding of CCIMP project as a joint effort with CUNY. Columbia University and NASA GISS for support in planning CCIMP, and for initial GCM data Outside reviewers of CCIMP project

Extra

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State System -Operating Rules -Demand Water Quality Operational Support Flows System Performance - Storage - Demand - Spills Turbidity -Freq / Magnitude -Alum Decisions

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Demand Projections System Infrastructure Water System Planning Flows System -Operating Rules -Demand System Performance - Storage - Demand - Spills Turbidity -Freq / Magnitude -Alum Decisions Operating Rules

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Operating Decisions Flow Forecasts Operation Support Tool (OST) Flows System -Operating Rules -Demand Turbidity -Freq / Magnitude -Alum Decisions Demand Projections System Infrastructure Operating Rules

Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Climate Change Adaptation - OST Flows System -Operating Rules -Demand System Performance - Storage - Demand - Spills Turbidity -Freq / Magnitude -Alum Decisions Climate Change (Delta Change, SDM,RCM) Demand Projections System Infrastructure Operating Rules

Climate Change (Delta Change, SDM,RCM) Watershed Models (GWLF-VSA, SWAT) Models Flows WQ Loads Integrated Modeling System Watershed - Land Use - Soils - Topography - Hydrography - GIS Based - Management Data Time Series - Meteorology - Flows - WQ Reservoir Models (1D Hydrothermal Eutrophication, CEQUAL-W2) Reservoir WQ Reservoir - Bathymetry - Infrastructure System Model (OASIS) Flows Operations Results Watershed Management Land Use Changes Changes Trophic State Climate Change Analysis – Phase II Watershed -Sediment -Nutrients -Ecosystem Flows System -Operating Rules -Demand System Performance - Storage - Demand - Spills Turbidity -Freq / Magnitude -Alum Decisions Demand Projections System Infrastructure Operating Rules

Potential Climate Change Effects on NYC Water Supply System Operation Hydro-thermal Effects Increased Water Temperature Reduced Ice Cover Longer Period of Thermal Stratification Changes in Reservoir Water level and Residence Time Hydrology Effects Increased Evapotranspiration Increased Precipitation Changes in Winter Precipitation, Snow Accumulation, and Timing of Snowmelt Changes in Antecedent Conditions Changes in Partitioning Between Sub- surface and Surface Runoff Changes in the Amount and Seasonality of Stream Flow Nutrient Loading Effects Changes in the Frequency and Magnitude of Storm Events Changes in the Timing of Nutrient Loading Changes in Proportion of Surface Runoff Changes in Watershed Biogeochemistry Reservoir Trophic Status Changes in the Timing and Magnitude of Nutrient Inputs Changes in the Nutrient Availability Due to Changes in Stratification and Mixing Changes Phytoplankton Growth and Succession Due to Changes in Water Temperature and Light Extinction Changes in Hypolimnetic Oxygen and Nutrients Reservoir System Operation Changes in Water Inputs Changes in Water Loss (Spill) Water Quality Related Restrictions on Use Changes in System Operation Future Demand