Tools For Drought Management Water Management in the face of droughts

Tools For Drought Management

• Water Management in the face of droughts

• require

• Skilful Hydrologic Forecasting/Simulation Tool
• Statistical or Hydrologic Models (PRMS, SWAT, etc.)
• for ~seasonal time scales
• Stochastic Flow Simulation tools for longer term (multi-year, decades) planning and management
• Decision Support tool of the agriculture/water resources system
• RiverWare

Seasonal Streamflow Forecast/ Simulation

• Hydrologic Models

• PRMS, SWAT

• Statistical Models

• Nonlinear Regression approach for ensemble forecasts
• [incorporating large-scale land-ocean-atmospheric information, Grantz et al., 2005; Regonda et al., 2006]
• Skilful, provides uncertainty estimates via ensembles

Truckee / Carson Basin - Application

• Study Area

• Hydroclimatology, Management

• Spring Streamflow Forecast Models

• [incorporating large-scale land-ocean-atmospheric information, Grantz et al., 2005]

• Decision Support Model

• Drive the streamflow forecast through the decision model. Investigate skills in the decision variables

Average Monthly Flows

• Primarily snowmelt driven basins

• (April, May, June)

• Correlate Fall/ Winter Climate Signals with AMJ Streamflow

Management Issues

• Irrigation/Agriculture decisions on the Newland Irrigation district are made in Feb much before the peak flow occurs

• So, skilful long-lead seasonal streamflow forecasts on Truckee and Carson Rivers are required

• Forecasts determine

• How storage targets will be met
• on the Lahonton reservoir for
• irrigation
• How much water to divert
• from Truckee to Carson via
• the Truckee Canal
• How much water will be
• available for Irrigation

Decision Variables

RiverWare – River and Reservoir Decision Support System

Truckee-Carson RiverWare Model

Winter Climate Link

• Identified large scale land-ocean-atmosphere predictors for Truckee/Carson spring (April-June total) streamflow

• Used a Nonlinear regression framework (local polynomials) to generate ensemble of spring streamflow forecasts

• Forecasts issued on the 1st of each month starting from Nov 1st through April 1st

• Skills evaluated using correlation coefficient and RPSS

• (RPSS = 1 implies categorical forecast, 0, no better than climatology)

Forecasting Results

Forecast Ensembles are Used to drive the Decision Support System for the Truckee/Carson Baisn (Forecast skills of the decision variables evaluated)

Decision Model Results

Dry Year: 1994

Wet Year: 1993

Normal Year: 2003

Exceedance Probabilities

Summary

• Developed a streamflow forecast framework incorporating large-scale ocean-atmospheric-land variables

• Skilful long-lead streamflow forecasts obtained on the Truckee/Carson river basin ~4-5 months ahead of the spring peak flow

• Developed a Decision Support System that incorporates all the management aspects of the water resources system

• Skilful streamflow forecasts translated into skills in the decision variables – especially the amount of flow available for irrigation

• The Integrated streamflow-Decision Support System provides a robust framework for effective management of droughts both in the

• short and longer time scales

• Streamflow scenarios can be generated conditioned on climate change, land use change, water use change etc. and management/decision strategies evaluated

Acknowledgements Ms. Katrina Grantz for USBR Truckee Office for financial support of this study CADSWES for computation and logistics support