GoldSim Technology Group LLC, 2006

Slide 1

Water Balance Modeling Techniques

GoldSim Technology Group LLC, 2006

Slide 2

Overview

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

Do you have any favorite techniques that you would like to share?