Modeling hydrologic processes

Groundwater flow and transport models

• What information can be drawn from the hydraulic head?
• where the water is flowing
• how fast it is flowing
• how much water there is -> storage coefficient
• point meaurements of the hydraulic head can be contoured and used to derive flow directions in three dimensions
• groundwater flow perpendicular to equipotential lines (lines of equal hydraulic head) if hydraulic conductivity is not dependent on direction
• groundwater flow influenced by topography (Fig)
• groundwater flow influenced by geology (Fig)
• losing and gaining streams, amn example from western Hungary (Fig)
• student excercise:
• look at the provided map that shows the hydraulic head distribution for a site in western Hungary
• put flowlines onto the map
• which streams are gaining, which are losing?
• modeling groundwater flow requires the following:
• measurement of the hydraulic head at as many locations as possible
• determination of the hyraulic conductivity at as many places as possible
• knowledge of the geology
• boundary conditions (know flow, or fixed hyraulic head)
• construction of a grid in two or three dimensions
• solving the groundwater flow (balance) equation
• adjusting parameters until the predicted and the measured hyraulic heads match as closely as possible
• model can then be used to predict the future behaviour of the aquifer system under different scenarios
• modeling groundwater transport requires in addition:
• dispersion/adsorption/decay constants
• source function of pollutants
• Demonstration of the groundwater flow/transport modeling package Visual Modflow
• Visual Modflow is a software package that allows users to model groundwater flow and transport
• it is highly interactive and allows modeling a real aquifer system in three dimensions
• site description
• grid, wells, hydraulic conductivity
• hydraulic head distribution
• contamination plume in three dimensions

Watershed Management - A computer simulation

INTRODUCTION

A watershed, or drainage basin, is the land area that delivers water, sediments, and dissolved substances to a particular body of water. Many activities occuring in a watershed contribute to the availability of water. The watershed simulator helps you learn what it takes to manage a watershed to meet the water needs you have selected. This model integrates physical properties of the watershed incl. surface waters and groundwater, as well as management parameters, like how many people are sup

INVESTIGATION 1: The natural system

Look at Rogue and Colorado @ Grand Canyon and @Hoover Dam in comparison.

• Q1: Are the rivers higher during one part of the year or another?
• Q2: Why is the seasonality different for different rivers?
• Q3: Where does the water come from?
• Q4: Do natural streams systems experience flooding or stream dewatering?

INVESTIGATION 2: Municipal use of water

Look at the Salt River

• Q5: When does the municipal demand peak?
• Q6: What is this water used for?
• Q7: How much difference is there between the minimum and maximum water demand?
• Q8: Choose GW as the sole source of water. How is the aquifer affected by this policy?
• Q9: What are the advantages and disadvantages of using SW vs GW as source? What is the most reasonable strategy?
• Q10: How many people can you support before you begin to have water shortages?

INVESTIGATION 3: Agricultural use of water

• Q11: When does the agricultural demand peak?
• Q12: What is the water used for?
• Q13: How much difference is there between the minimum and maximum water demand?

INVESTIGATION 4: Water for Electrical Power Generation

Try to operate the power plant on the salt river.

• Q14: What do you observe?

INVESTIGATION 5: Reservoir management

• Q15 : During which parts of the year should you try to save the water in the reservoir and when should you allow the reservoir to be drawn down?
• Q16 : Which size reservoir is the easiest to manage?

INVESTIGATION 6: Water quality

• Q16: How does the water quality change along the river?
• Q17: Can you explain the variation in time?

INVESTIGATION 7: Putting the ideas together

Running the simulation as a group: - mouse operator, municipal water manager, agricultural water manager, reservoir operator; (possibly add environmental monitor positions) Watershed manager: - flexible salary set priorities, you win/loose $300, 200, or 100 for meeting/not meeting the priorities.