HYDROLOGIC PROCESSES

PURPOSE:
This lab examines 1) the data and methods used to analyze the potential for and causes of flooding by examining a case history and 2) the migration of contaminants in the groundwater.

KEY TERMS AND CONCEPTS: Be sure you understand these.
Physical:
• Stream
• Channel, bank, floodplain
• Meandering vs. braided streams
• Inside vs. outside of meander bends
• Cross sectional area = Width * Depth
• Watershed-drainage area
• Gauging station
• Storm intensity; runoff
• Watershed, headwaters
• Tributary creek
• Water velocity (V) e.g. ft/sec Hydrological:
• Discharge (Q = A x V)
e.g. cfs = cubic feet per second
• Hydrograph
• Bankfull discharge
• Flood
• Stage (water height above channel bottom)
• Lag time
• Groundwater contour line
• Groundwater flow line
• Thalweg
• Point Bar
• Cut Bank

INTRODUCTION:
About 97% of the Earth’s water is in the oceans. The remaining 3% is fresh H2O, ice, liquid, and water vapor. Of that 3%, the majority, about 69%, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining fresh water, almost all of it is below your feet, as ground water. Practically anywhere on Earth, at some depth underground the rock/sediment is saturated with water. Of all the fresh water on Earth, only about 0.3 percent is contained in rivers and lakes—yet rivers and lakes are what we are most familiar with.

San Joaquin Valley residents rely heavily on groundwater as our primary source of drinking water. Keeping the groundwater supply safe and free of contaminants is vital to our wellbeing. Understanding how groundwater flows and what contaminant risks exist in our valley can aid us in keeping up the quality of our drinking water.

Water is our most valuable commodity but also can pose various hazards, including flooding and groundwater contamination. If one lumps together all kinds of flooding, including that caused by hurricanes and other severe weather, it is the most lethal of all the natural disasters. Each year, inundations result in thousands of deaths and billions of dollars in damages. Most of these could be prevented by understanding the causes of flooding, wise land use planning, and developing adequate emergency procedures.

Groundwater contamination in the San Joaquin Valley can come from many sources including septic systems, storage tanks, fertilizers, pesticides, and landfills. The U.S. today, is thought to contain 20,000 known abandoned and uncontrolled hazardous waste sites, with the numbers increasing annually. Such sites can lead to groundwater contamination, when containers like hazardous materials storage tanks and barrels leak onto/into the ground and the contents eventually make their way down through the soil and into groundwater.

SECTION 1. SURFACE WATER: FLOODING

BACKGROUND:
In the early morning of September 18, 1998 floodwaters from Green and Blue Creeks surged down Rush Creek, hitting the town of Woodhaven with unprecedented force (Fig. 11.1). Woodhaven, situated on the inside of a meander bend, was severely damaged. Downstream, the town of Millbrook, also situated on the inside of a meander bend, fared only slightly better; Vista Bluffs on the outside of a meander bend was unaffected save for severe bank erosion that required stabilization. The floodwater levels on Rush Creek are indicated by the three cross sections A-A’, B-B’, and C-C’ on Figure 11.1.

The flood was initiated by a brief but intense thunderstorm that began about midnight and dropped nearly an inch of water onto the watershed. The ground was dry before the storm. Flooding of this extent had not been recorded since Woodhaven was founded in 1922.

The area’s economy is almost entirely supported by logging; the foothills north of town are heavily forested in fir trees (conifers). However, clear cutting removed most of the timber in the headwaters of Green Creek during the summer of 1998.

Basic Stream Hydrology:
How water flows in a stream depends on the shape of the stream’s channel. The channels of meandering streams are fairly deep and narrow, and they wind and curve, forming meander bends whose inside banks are lower elevation than on the outside of the bend. Consequently, floodwaters will first inundate the inside banks. The channel network of braided streams are shallow, broad, and fairly straight. Their banks are usually the same height, so flood waters flow out of both sides of the channel equally.

Water does not flow uniformly down a stream channel, but rather, it varies in velocity and volume. The volume of water that flows past a certain point in the channel in a given time is called the discharge (Q), and is the product of the water’s velocity (V) multiplied by the cross sectional area of the channel (A); therefore, Q=V*A. 

Sample Solution

HYDROLOGIC PROCESSES

PURPOSE:
This lab examines 1) the data and methods used to analyze the potential for and causes of flooding by examining a case history and 2) the migration of contaminants in the groundwater.

KEY TERMS AND CONCEPTS: Be sure you understand these.
Physical:
• Stream
• Channel, bank, floodplain
• Meandering vs. braided streams
• Inside vs. outside of meander bends
• Cross sectional area = Width * Depth
• Watershed-drainage area
• Gauging station
• Storm intensity; runoff
• Watershed, headwaters
• Tributary creek
• Water velocity (V) e.g. ft/sec Hydrological:
• Discharge (Q = A x V)
e.g. cfs = cubic feet per second
• Hydrograph
• Bankfull discharge
• Flood
• Stage (water height above channel bottom)
• Lag time
• Groundwater contour line
• Groundwater flow line
• Thalweg
• Point Bar
• Cut Bank

INTRODUCTION:
About 97% of the Earth’s water is in the oceans. The remaining 3% is fresh H2O, ice, liquid, and water vapor. Of that 3%, the majority, about 69%, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining fresh water, almost all of it is below your feet, as ground water. Practically anywhere on Earth, at some depth underground the rock/sediment is saturated with water. Of all the fresh water on Earth, only about 0.3 percent is contained in rivers and lakes—yet rivers and lakes are what we are most familiar with.

San Joaquin Valley residents rely heavily on groundwater as our primary source of drinking water. Keeping the groundwater supply safe and free of contaminants is vital to our wellbeing. Understanding how groundwater flows and what contaminant risks exist in our valley can aid us in keeping up the quality of our drinking water.

Water is our most valuable commodity but also can pose various hazards, including flooding and groundwater contamination. If one lumps together all kinds of flooding, including that caused by hurricanes and other severe weather, it is the most lethal of all the natural disasters. Each year, inundations result in thousands of deaths and billions of dollars in damages. Most of these could be prevented by understanding the causes of flooding, wise land use planning, and developing adequate emergency procedures.

Groundwater contamination in the San Joaquin Valley can come from many sources including septic systems, storage tanks, fertilizers, pesticides, and landfills. The U.S. today, is thought to contain 20,000 known abandoned and uncontrolled hazardous waste sites, with the numbers increasing annually. Such sites can lead to groundwater contamination, when containers like hazardous materials storage tanks and barrels leak onto/into the ground and the contents eventually make their way down through the soil and into groundwater.

SECTION 1. SURFACE WATER: FLOODING

BACKGROUND:
In the early morning of September 18, 1998 floodwaters from Green and Blue Creeks surged down Rush Creek, hitting the town of Woodhaven with unprecedented force (Fig. 11.1). Woodhaven, situated on the inside of a meander bend, was severely damaged. Downstream, the town of Millbrook, also situated on the inside of a meander bend, fared only slightly better; Vista Bluffs on the outside of a meander bend was unaffected save for severe bank erosion that required stabilization. The floodwater levels on Rush Creek are indicated by the three cross sections A-A’, B-B’, and C-C’ on Figure 11.1.

The flood was initiated by a brief but intense thunderstorm that began about midnight and dropped nearly an inch of water onto the watershed. The ground was dry before the storm. Flooding of this extent had not been recorded since Woodhaven was founded in 1922.

The area’s economy is almost entirely supported by logging; the foothills north of town are heavily forested in fir trees (conifers). However, clear cutting removed most of the timber in the headwaters of Green Creek during the summer of 1998.

Basic Stream Hydrology:
How water flows in a stream depends on the shape of the stream’s channel. The channels of meandering streams are fairly deep and narrow, and they wind and curve, forming meander bends whose inside banks are lower elevation than on the outside of the bend. Consequently, floodwaters will first inundate the inside banks. The channel network of braided streams are shallow, broad, and fairly straight. Their banks are usually the same height, so flood waters flow out of both sides of the channel equally.

Water does not flow uniformly down a stream channel, but rather, it varies in velocity and volume. The volume of water that flows past a certain point in the channel in a given time is called the discharge (Q), and is the product of the water’s velocity (V) multiplied by the cross sectional area of the channel (A); therefore, Q=V*A. 

Sample Solution

HYDROLOGIC PROCESSES

PURPOSE:
This lab examines 1) the data and methods used to analyze the potential for and causes of flooding by examining a case history and 2) the migration of contaminants in the groundwater.

KEY TERMS AND CONCEPTS: Be sure you understand these.
Physical:
• Stream
• Channel, bank, floodplain
• Meandering vs. braided streams
• Inside vs. outside of meander bends
• Cross sectional area = Width * Depth
• Watershed-drainage area
• Gauging station
• Storm intensity; runoff
• Watershed, headwaters
• Tributary creek
• Water velocity (V) e.g. ft/sec Hydrological:
• Discharge (Q = A x V)
e.g. cfs = cubic feet per second
• Hydrograph
• Bankfull discharge
• Flood
• Stage (water height above channel bottom)
• Lag time
• Groundwater contour line
• Groundwater flow line
• Thalweg
• Point Bar
• Cut Bank

INTRODUCTION:
About 97% of the Earth’s water is in the oceans. The remaining 3% is fresh H2O, ice, liquid, and water vapor. Of that 3%, the majority, about 69%, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining fresh water, almost all of it is below your feet, as ground water. Practically anywhere on Earth, at some depth underground the rock/sediment is saturated with water. Of all the fresh water on Earth, only about 0.3 percent is contained in rivers and lakes—yet rivers and lakes are what we are most familiar with.

San Joaquin Valley residents rely heavily on groundwater as our primary source of drinking water. Keeping the groundwater supply safe and free of contaminants is vital to our wellbeing. Understanding how groundwater flows and what contaminant risks exist in our valley can aid us in keeping up the quality of our drinking water.

Water is our most valuable commodity but also can pose various hazards, including flooding and groundwater contamination. If one lumps together all kinds of flooding, including that caused by hurricanes and other severe weather, it is the most lethal of all the natural disasters. Each year, inundations result in thousands of deaths and billions of dollars in damages. Most of these could be prevented by understanding the causes of flooding, wise land use planning, and developing adequate emergency procedures.

Groundwater contamination in the San Joaquin Valley can come from many sources including septic systems, storage tanks, fertilizers, pesticides, and landfills. The U.S. today, is thought to contain 20,000 known abandoned and uncontrolled hazardous waste sites, with the numbers increasing annually. Such sites can lead to groundwater contamination, when containers like hazardous materials storage tanks and barrels leak onto/into the ground and the contents eventually make their way down through the soil and into groundwater.

SECTION 1. SURFACE WATER: FLOODING

BACKGROUND:
In the early morning of September 18, 1998 floodwaters from Green and Blue Creeks surged down Rush Creek, hitting the town of Woodhaven with unprecedented force (Fig. 11.1). Woodhaven, situated on the inside of a meander bend, was severely damaged. Downstream, the town of Millbrook, also situated on the inside of a meander bend, fared only slightly better; Vista Bluffs on the outside of a meander bend was unaffected save for severe bank erosion that required stabilization. The floodwater levels on Rush Creek are indicated by the three cross sections A-A’, B-B’, and C-C’ on Figure 11.1.

The flood was initiated by a brief but intense thunderstorm that began about midnight and dropped nearly an inch of water onto the watershed. The ground was dry before the storm. Flooding of this extent had not been recorded since Woodhaven was founded in 1922.

The area’s economy is almost entirely supported by logging; the foothills north of town are heavily forested in fir trees (conifers). However, clear cutting removed most of the timber in the headwaters of Green Creek during the summer of 1998.

Basic Stream Hydrology:
How water flows in a stream depends on the shape of the stream’s channel. The channels of meandering streams are fairly deep and narrow, and they wind and curve, forming meander bends whose inside banks are lower elevation than on the outside of the bend. Consequently, floodwaters will first inundate the inside banks. The channel network of braided streams are shallow, broad, and fairly straight. Their banks are usually the same height, so flood waters flow out of both sides of the channel equally.

Water does not flow uniformly down a stream channel, but rather, it varies in velocity and volume. The volume of water that flows past a certain point in the channel in a given time is called the discharge (Q), and is the product of the water’s velocity (V) multiplied by the cross sectional area of the channel (A); therefore, Q=V*A. 

Figure 11.1. Map of the Rush Creek watershed and cross sections of the 1998 flood levels.

The height that water rises above the channel bottom is called the stage. When the channel is completely full of water it is at bankfull stage; flooding occurs when the stage is over bankfull. Floodwaters will flow across the stream’s floodplain, causing drowning and extensive property damage. Eventually, the waters either evaporate, flow back into the stream, or infiltrate (seep into groundwater), reducing the flow below bankfull.

How much water runs off and how much infiltrates during a particular rainstorm depends on the geological conditions where the rain falls. On hard, impermeable surfaces like rock, pavement, or dry soil, the water runoff is high and velocity is rapid, causing flooding. Vegetation slows runoff and vegetated soil is soft and loose, promoting infiltration., Therefore, floods are less common and less severe in densely-vegetated areas compared to paved or rocky areas, given the same rainfall.

Not all floods are of equal severity. Fortunately, the most severe floods occur the least often. A system has been developed to predict the discharge and frequency of floods based on stream discharge data. The most common use of this is to characterize the “100-year flood”, the maximum discharge that is likely to occur in any 100-year period. This doesn’t mean that this discharge will occur only once in 100 years because there is a 1% chance that this discharge will occur in any year. 100-year flood could occur on consecutive years, but it’s unlikely. Just like flipping a coin a getting multiple “heads” in a row is unlikely, but possible. It is important to remember that these discharges are based on past flows. Any changes to the channel volume or shape, or to the runoff characteristics of the watershed, can greatly affect the discharge of the particular flow events. For instance, if runoff is increased, the magnitude of the 100-year flood will be greater than the historical averages, and can occur more often than once per 100 years.

METHOD:
In this lab, you will undertake an analysis of the 1998 Rush Creek flood. This requires that you make mathematical calculations in addition to plotting and interpreting graphs. Read through the questions and text carefully, and be certain you understand the math. Do all calculations neatly on the worksheet. Be sure you include the correct units!

A. CONSTRUCTING THE STREAM HYDROGRAPHS FOR GREEN AND BLUE CREEKS
Stream hydrographs plot the discharge of water vs. time. The shape of the curve conveys how quickly the water rises and falls in the channel, and how long a particular discharge continues in the channel. The top of the curve is the peak discharge, indicating the time and amount of the highest flow. The watersheds of Green and Blue Creeks are about the same size. As well, the two creeks are of similar length and depth.

A1) Refer to Table 11.1 on p. 11-11, noting the discharges and times for flows on Green Creek and Blue Creek as measured every hour at the automatic gauging stations indicated on Figure 11.1. The units of discharge are measured in cubic feet per second (cfs).

Using the values from table 11.1, plot the discharge vs. time for the two creeks on Figure 11.2 on page 11-11.  After plotting the points, connect them with a smooth curve. Make sure to differentiate the line for Green Creek from the one for Blue Creek.

A2) Examine the two curves. What was the maximum-recorded discharge for Green Creek gauging station? Blue Creek gauging station? Were these flows actually measured?

A3) Do these values represent the maximum discharges that actually occurred? Explain.

A4) What, in your estimation, was the maximum discharge of each creek?

A5) The lag time is the difference between the time the storm began and the peak discharge. Recall that the storm began about midnight. What was the lag time of the peak flow at Green Creek gauging station? At Blue Creek gauging station? (Note: all times are AM.)

A6) Why are the lag times for the two streams different?

B. DETERMINING THE BANKFULL DISCHARGE OF RUSH CREEK
Determining the bankfull discharge is important because it conveys the discharge of water above which flooding will occur. Figure 11.3 below, shows an enlarged view of the A-A’ cross section from Figure 11.1 depicting the cross section of Rush Creek at the Woodhaven gauging station. Note that Woodhaven sits on the inside of a meander bend where the banks are low and flat. The gray area represents the water level at bankfull. The channel’s cross sectional area at bankfull can be approximated by a rectangle 8 ft deep and 12 ft across as shown.

Figure 11.3. Cross section of Rush Creek at Woodhaven gauging station at bankfull discharge. For location, refer to Figure 11.1.

B1) Determine the cross sectional area of Rush Creek at bankfull stage based on the dimensions of the rectangle. Remember that the area is calculated by width x depth.

B2) At the Woodhaven gauging station, previous measurements of the water velocity during bankfull stage were 2.5 ft/sec (feet per second). Using Equation 11.1 below, calculate the bankfull discharge at Woodhaven in cfs.

Eq. 11.1            Area    x   Velocity  = Discharge
                    A     x       V        =      Q 

            Units:      ft2    x    ft/sec     =     ft3/sec (or cfs)

C. DETERMINING THE FLOOD STAGE
The stage of a stream is the height of the water above its channel bottom. Stage is measured on a stream staff (like a vertical ruler) during rising and falling discharges. Knowing the stage is critical to determining how high the floodwaters could be across a floodplain.

During the Woodhaven flood, water from both Green and Blue Creeks combined and flowed down Rush Creek where the peak discharge was measured at 970 cfs. Figure 11.4 relates discharge to stage at the Woodhaven gauging station based on previous data. The point plotted represents bankfull discharge; at bankfull, the stage is 8 ft -the channel depth based on Figure 11.3.

Figure 11.4. Stage-discharge (Q) plot of Rush Creek at Woodhaven gauging station. Plotted point is bankfull discharge.

C1) Examine Figures 11.3 and 11.4. Why does stage increase sharply up to bankfull, then increase more gradually beyond that?

C2) Based on Figure 11.4, what was the floodwater stage at Woodhaven during the peak discharge of 970 cfs? How deep was the water in the town of Woodhaven?

C3) Determine the number of gallons of water that passed during the peak flood hour assuming an average flow during that time of 900 cfs. To do this, first, determine the number of seconds in an hour and multiply by the discharge to get the number of cubic feet per hour. Then, multiply by 7.5 gallons per cubic foot.

D. THE FLOOD WARNING SYSTEM

Automatic flood warning systems are installed on tributary streams so that a flood alert can be sent via radio to towns on the main stream if waters on the tributary rise above a certain stage. In 1987, the State decided to install such a system for towns on Rush Creek. Since the devices are very expensive, only one was installed. At the time, both Green and Blue Creeks had similar flow characteristics, so either stream would give sufficient warning; Blue Creek was arbitrarily chosen.

D1) The warning was set to go off when the discharge on Blue Creek reached 250 cfs. Examine the flood hydrograph you plotted (Fig. 11.2). What time did Green Creek’s discharge reach 250 cfs? What time did Blue Creek’s discharge reach 250 cfs? At what time did the first alarm go off?

D2) Calculate the time it takes the water to leave the gauging station and reach Woodhaven. Woodhaven is 3.5 miles downstream of the gauging station on Blue Creek. Based on the measured velocity of 10 ft/sec, calculate the elapsed time (in minutes) between the first alarm and the time floodwaters “should have” arrived at Woodhaven. (1 mi=5,280 ft)

D3) At what time did the first floodwaters actually arrive at Woodhaven? Explain. Since floodwaters from either Green or Blue Creeks would flow down Rush Creek, did the residents have sufficient warning of the flood? (Hint: examine the hydrograph, Fig. 11.2 Check which creek hit flood stage (250 cfs) first.)

SECTION 2. GROUNDWATER CONTAMINATION

METHOD: Read through the questions and answer each in the space provided on the worksheet.

E1) Imagine that you live in the country and your neighbor’s septic system is 0.25 miles up the groundwater flow path from your water well. If the groundwater is in gravel beds and the water flows at 42 inches per hour, how long would it take for tasty dissolved material from your neighbor’s septic system to reach your water well?

E2) If you and your neighbor lived in houses built on granite (a solid crystalline rock) in which groundwater flow at 0.13 inches per day (through cracks), and your neighbor’s septic system was 0.25 miles up the groundwater flow path from your well, how long would it take for dissolved material to reach your water well?

E3) What accounts for the difference in arrival time between scenarios (1) and (2) above?

The attached map (Figure 11-5) is a depiction of a hypothetical area underlain by well-sorted coarse sand crossed by a permanent stream, Clear Creek, flowing in a southeasterly direction. The ground surface is gently sloping to the southeast, and the shallow water table is defined by the water table contours. The location of a dump is shown on the map. The dump is privately owned and operated by a small company that hauls trash and garbage for residents of a nearby small town. The dump is an excavated pit, the bottom of which lies just above the water table.

The Jones property lies southeast of the dump, and its west property line borders on Clear Creek. Mr. Jones owns horses that he keeps in the barn and corral part of the time. The rest of the time the horses graze on the property and occasionally drink the water from Clear Creek.

The Smith estate lies west of Clear Creek and also has frontage on the creek. Both Jones and Smith derive their domestic water supplies from wells that penetrate the shallow water table. To assure themselves that the water was suitable for human consumption, Jones and Smith had well-water samples analyzed by the county health department at the time their wells were completed. Both Smith and Jones owned their respective properties for many years prior to the establishment of the dump and enjoyed potable water until recently.

Recently, Jones’ well water quality began to deteriorate. T Jones verified this b having his water tested at the county health department. Jones attributed this to pollution of the groundwater from leaching of domestic waste deposited in the dump. In talking with his neighbor Smith, Jones suggested that the two of them should file suit against the owner of the dump and obtain a court injunction that would require cessation of all further dumping.

So, Smith had water from his well tested again and found that it had not changed in quality since the tests conducted prior to the creation of the dump. Yet stream samples along the stretch that forms the boundary between the Jones and Smith properties were also analyzed by the health department and were found to be contaminated by materials similar to those found in the recent samples from the Jones well. This was sufficient evidence to convince Smith that he ought to join in the suite with Jones against the dump operator. Smith reasoned that if the creek were contaminated with the same materials found in the Jones well, it would be only a matter of time until his well would also be polluted.

At this point, Jones and Smith hired an attorney to file the suit. The attorney sought the advice of a geologist at a nearby university who had access to USGS publications in the school’s library. There the geologist discovered a report of the geology of the area. A section of the report on groundwater contained a map showing water table contours based on static water levels in other wells not shown in the figure. The geologist transferred those contours to a map he was preparing for the lawyer. This map is shown below.

Using the following rules, sketch a network of flow lines of the map:

  • Flow lines cross groundwater contour lines at right angles (90º).
  • Flow lines curve in toward streams and or lakes where groundwater is discharged.

(Use a soft black pencil because you may have to erase several times before you are satisfied with your results.) Extend the flow lines across the entire map area so that the movement of groundwater can be ascertained. A sample flow line has been drawn on the map for you.

On the basis of the flow line network that you have constructed, answer the following questions on the worksheet.

E4) Is there reasonable evidence to conclude that seepage from the dump has contaminated the Jones well? Explain.

E5) Is there reasonable evidence that the stretch of Clear Creek adjoining the Jones and Smith properties has been contaminated by seepage from the dump? Explain.

E6) Is there reasonable evidence that the Smith well will be contaminated by seepage from the dump at some time in the future? Explain.

E7) Is it possible that the animal waste in the corral on the Jones property is responsible for polluting the Jones well, any part of Clear Creek, or the Smith well, eventually? Explain.

Name: Day & Time:

ANSWER SHEET – LAB #11: HYDROLOGIC PROCESSES

SECTION 1. SURFACE WATER: FLOODING

A. CONSTRUCTING THE STREAM HYDROGRAPHS FOR GREEN AND BLUE CREEKS

A1) •= Green Creek = Blue Creek.

Table 11.1 Stream discharge measurements.

00:00   01:00   02:00   03:00   04:00   05:00   06:00   Time

Green Ck 45 545 355 135 70 60 50 cfs
Blue Ck 55 130 370 415 125 105 85 cfs

Figure 11.2 Stream hydrographs for 1998 flood event on Blue and Green Creeks.

A2) Maximum discharge recorded for Green Ck? Blue Ck?

A3) Were these values the actual maxima that occurred? Explain.

A4) Your estimation for Green Creek? Blue Creek?

A5) Lag time of peak flow on Green Creek Blue Creek

A6) Why different?

B. DETERMINING THE BANKFULL DISCHARGE OF RUSH CREEK

B1) Cross-sectional area of Rush Creek at bankfull stage:

B2) Bankfull discharge A x V= Q x =

C. DETERMINING THE FLOOD STAGE

C1) Why stage increases sharply to bankfull, then increases gradually:

C2) Floodwater stage at peak discharge of 970 cfs:

Water depth in town                                 

C3) Gallons of water per hour at 900 cfs:
(1 cu ft = 7.5 gal) Hint: reread the question for specific direction.)

D. THE FLOOD WARNING SYSTEM

D1) Green Creek: Blue Creek: Time of alarm:

D2) Elapsed time (in minutes)
(1 mi=5,280 ft)

D3) Flood arrival time:
Hint: Look at table 11.1 for the first flood waters.

Sufficient warning? Explain.

E. GROUNDWATER CONTAMINATION

E1) Time:

E2) Time:

E3) Difference:
E4) Jones well contaminated? Explain:
E5) Clear Creek contaminated? Explain:
E6) Future contamination:
E7) Contamination from corral:

Sample Solution