Water Balance Modeling Techniques
GoldSim Technology Group LLC, 2006
Slide 1
Overview
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Reservoir basics
– Overflow_Rate, Withdrawal_Rate, changing upper bound
– Using Extrema elements to track high and low extremes
– Using Status elements to track the status of a Reservoir (and
control actions such as pumping)
Using Time Series elements for precipitation and other
histories
Using Material Delay elements to simulate seepage and flow
Using Convolution elements to simulate a runoff using a
unit hydrograph
Generating stochastic precipitation, evaporation and flow
histories
Using Allocators and Splitters
Using the Reliability Module to simulate equipment failure
Share your own techniques
GoldSim Technology Group LLC, 2006
Slide 2
Reservoir Basics
 Overflow Rate
 Using the Withdrawal Rate output
 Varying the Upper Bound (to simulate silting
up)
 Using an Extrema to track peaks/valleys
 Using a Status element to track status of a
Reservoir and control actions (such as
pumping)
GoldSim Technology Group LLC, 2006
Slide 3
Using Time Series Elements in Water
Balance Models
 Useful for inputting precipitation,
evaporation and other time series
 Important to:
– Differentiate between rates and values
– Differentiate between instantaneous flows
and averages flows
 Can import data from spreadsheets
GoldSim Technology Group LLC, 2006
Slide 4
Using Material Delay Elements to
Simulate Seepage and Flow
 Delay Time is mean velocity of flow
 Dispersion can simulate spreading
– Both can be specified as a function of
hydrogeologic properties
– Both may change with time (e.g., is material
at field capacity?)
GoldSim Technology Group LLC, 2006
Slide 5
Using Convolution Elements to Simulate a
Runoff Using a Unit Hydrograph
 A Convolution element converts an input
signal to an output signal via a transfer
function
– You provide an input signal (e.g., rainfall rate)
and a transfer function (the unit hydrograph)
– The convolution integral applies the transfer
function and computes an output (e.g.,
runoff)
 A Delay is a specialized instance of a
convolution integral
GoldSim Technology Group LLC, 2006
Slide 6
Generating Stochastic Precipitation,
Evaporation and Flow Histories
 Option1: Build your own Markov (or other)
model manually
 Option2: Using autocorrelated Stochastics
 Option3: Use the History Generator element
GoldSim Technology Group LLC, 2006
Slide 7
Splitters and Allocators
 Should be very powerful elements for water
balance models
 Splitters split (distribute) flows
 Allocators route flows based on specified
demands and priorities
GoldSim Technology Group LLC, 2006
Slide 8
Using the Reliability Module to Simulate
Pumps and Other Equipment
 Simulate pump failure, as well as pumps
turning on and off
GoldSim Technology Group LLC, 2006
Slide 9
Do you have any favorite techniques that
you would like to share?
GoldSim Technology Group LLC, 2006
Slide 10