instrumentation and monitoring Exam 2

Describe the process by which raindrop impact detaches soil.

Raindrops hit the soil with a lot of energy because of that the soil particles get detached. A raindrop can be described by a soil bomb with speeds up to 30 miles per hour. The particles are thrown up and out. They are thrown in all directions evenly

Describe the process by which runoff flow detaches soil.

Runoff flow detaches soil by creating turbulent jets that are created when particles move down the slope. These turbulent eddies break down over time into smaller eddies two eddies are strong enough to break particles apart

What 2 factors control whether runoff will have enough power density to detach soil?

1) Velocity of Flow

2)Depth of flow

If runoff doesnt have nearly enough energy to detach particles, how can it still transport them downslope?

Gravity still have enough energy to drag the sediment down slow as it slows

Two common ways of surface cover

1) Lay down a grid

2)Remote with images

What happens if sediment load is larger than transport capacity?

Means you are going to get deposition

In lecture we mentioned 9 important characteristics of good rainfall simulators.  List 4 of these.

1) Drop Distribution

2) uniformity

3) Continuous

4) Impact is vertical

5)Repeatable

6) Portable

How do we measure rainfall uniformity over the area?

Cans that you put out on a grid

How do we know whether our sample extracted at a point in the stream cross-section is really representative?

We don't have to assume it is

What is the general rule lower limit on DO?

5 parts per million

Saturation is 9 ppm

What are 2 of the basic problems with measuring pesticide contamination of water?

1) Bound to the sediment

2) Has a short half-life constantly changing

3) often working in low concentrations

What does BOD stand for?

Biochemical oxygen demand

BOD is a measure of what (not what the abbreviation stands for, but what it means)?

Measure of the amount of food in the water

Describe a case in which you might be most interested in the mass transport of your contaminant.

Nitrogen and Phosphorus for algae blooms

Describe a case in which you might be most interested in whether your contaminant level exceeds some threshold value.

BOD- If you have a spike in it the fish are dead

Exceeding of a value or dropping below a value it will instally kill something the average does not matter

Describe at least 2 problems often experienced when looking for a contaminant threshold level.

1) You have to be able to catch a peak

2) How to catch something changing really quickly

Familiarization with a model

Understand Limitations, assumptions

The lecture description of how to use a model included 7 steps. Describe step use of results

Answer your question

The lecture description of how to use a model included 7 steps. Describe step #5: model validation

Use data not used in calibration and compare with model results

On what is the USDA-NRCS Soil Conditioning Index (SCI) based?

Based on a series of places where organic residue were added and soil organic carbon was measured.

Why are soil health and biotic integrity indices considered interpretive measures?

Measure and model things then have to decide if it is good or not. They need to be interprated.

In the study that looked at a multitude of factors affecting soil health, many of the chemical and physical factors were

determined to be secondary because they were strongly correlated to what easily-measured parameter?

1) Erosion

2) Soil Organic Carbon

In the study that looked at a multitude of factors affecting soil health, microbial activity (defined by community counts or CO2 production) and changes in bulk density were both discarded as having the wrong time scale. Explain

Microbial communities change fast they do not give a change in time period

Bulk density is to long term

Stream ecological health is defined on the basis of comparison to what?

Similar stream, Healthy Stream a good one to compare

List the 3 things we discussed that are very important in establishing a good relationship between turbidity readings and sediment concentration.

Calibrate it by doing both over a wide verity of storms with multiple data points in each storm

In order to be a good reference stream for this study stream, the reference stream should have what 2 characteristics?

Similar. Relatively unimpacted

We discussed 5 things that should be similar between the current and reference stream in order for a comparison to be meaningful. List 3 of those.

1) Climate

2) Geology in soils

3) Exposure to different species

Describe what causes overturn of lakes/reservoirs, and when it can normally occur.

Happens when you have cold over warm

Spring when Ice melts

Fall when temperature drop

In order to understand where in the lake/reservoir to take samples, need to account for 3 things. Name 2 of those.

1) Sources

2) Losses

3) Driving forces

Describe the steps in a paired watershed study.

Collect data to see if you really have similarity

Management changes on one of those collected data to see change.

What is the normal target velocity to maintain in sampler inlet tubes, and why is it so high?

Velocity is 5ft per second. Sediment could be falling out faster then it is going up

I mentioned two techniques used to collect runoff at the bottom of a plot. Very briefly describe one of these

Collection slot

Collection triangle

How do we keep sediment from settling in the collection area at the bottom of a field plot?

2% slope

Why is it hard to hydrologically isolate many watersheds in East Tennessee?

Karst topography

What is the biggest issue of concern when using a pumped sampler to extract a stream sample and sediment is a primary contaminant?

Where can you take it to get an accurate reading Ideally have something that does depth integration

What is isokinetic sampling?

The velocity in the sampler inlet is the same as stream velocity

In a study in West Tennessee looking at how often samples should be extracted so as to not miss important information, they found that you should take a sample every ______________________

5 minutes

How do we control the subsurface hydrology of field plot

Cutoff wall

Describe the steps in a calibration or before-after watershed study

Collect data before treatment and collect data after treatment to see if what you implemented change

weakness how it is going to change

What are some of the factors controlling lake/reservoir trapping efficiencies?

Sediment inflow rate

Sediment size distributions

Basin depth

basin storage

Describe why flow patterns through lakes/reservoirs can be very hard to predict.

multiple inlands that do not come in a channel baseflow into lake Impact of Lake stratification

Scientific model

Management model

Scientific model- Gain an idea of the whole ecosystem every factor included

Management model- Make a good management decisions

In lecture we mentioned 6 weaknesses of lab-scale studies. List 3 of these.

To Be reasonable it has to be really small and really heavy

1) Limited by weight and size

2) Hard to make conditions exactly right

3) Hard to get deep soil

4) Edge effects

Why will any collection scheme at the bottom of a plot affect sheet and rill erosion measurements?

It ends them the rills have to get out of the rill and come up and over the edge

Why is it hard to hydrologically isolate many watersheds in East Tennessee?

Karst Topography

Why is it not really possible to replicate watersheds?

Replicate behave the exact same everything even across the watershead

Describe how the channel system itself can affect watershed response.

It takes a log time for the channel to equilibrate

Describe the steps in a calibration or before-after watershed study.

Collect data for years before treatment

Put the treatment on and see how the data has changed

Understand how your site changed the location

Describe what sorts of contaminants appear with the first flush

Loose things on the surface Hydrocarbons are loose sediment

Describe what sorts of contaminants show a delayed concentration response.

Sediment it takes time to erode it always moving slower then the water

Anything that takes time to get in the water nutrients that travel with sediment

We mentioned 4 benefits of using a flow divider to sample runoff, rather than a flume and sampler. List 2 of those.

1) Cheaper

2) Continuous sample

3) Accurate

4) Measures sediment and runoff one device

What is the primary benefit of using a flume and sampler to sample runoff, rather than a flow divider?

It gives you a time variation value

We mentioned 3 problems associated with using a flume and sampler to sample runoff, rather than a flow divider. List two

Where to put the small sampler

When to take the Samplers

Flumes are expensive

How does the combination of baseflow and runoff in streamflow make sampling more difficult?

Baseflow is moving subsurface contamination

Erosion is moving surface they meet in a storm event

When sampling a stream for the impact of a factorys discharge, why would we not want to measure the concentration immediately downstream of the discharge point

It has not mixed in so it is not representative

When sampling a stream for the impact of a factorys discharge, what is the problem with measuring the concentration a calculated mixing distance downstream of the discharge point?

A lot of things interring in between

When sampling a stream for the impact of a factorys discharge, why do we also need to sample upstream of the discharge point?

Need to know what was actually added so you can change the factory accordantly

If we are interested in the impact of runoff coming into a stream from a field on one side, why why can we not just measure the contaminant in the stream above and below that field?

It does not account what is coming from the other side

Once we have decided where along a stream reach to take a sample, what must we do to get a representative sample within that cross-section?

Depth intergrated sampler take multiple readings across the cross section

How do we know whether our sample extracted at a point in the stream cross-section is really representative?

We dont

I extract a sample from a stream. What time period does the contaminant concentration in that sample really represent and what time period do we say it represents

It is that exact moment it represents from one sample from the next

In relation to the hydrograph, how would sediment from a distant upland source appear at the watershed mouth?

Later

Why is it probably a good idea to do intense sampling of several storm events at the beginning of a study?

Find out when stuff appears Know what times we need to look at for sediment

What is the biggest issue of concern when using a pumped sampler to extract a stream sample and sediment is a primary contaminant?

Where to put the inlet

Normal sediment

55-99

Lake and inflow rate

sediment flow rate base and depth

Why are flow patters in lake hard to predict

Base flow

Multiple inlet

Sediment

Flow coming in directly

What information does a reservoir bottom survey generally give us?

Sediment change over time

What information does lake turbidity measurement generally give us?

Suspended sediment and plankton

What information do you get by using a depth-integrated sampler in a lake or reservoir?

Average containment concentration over depth

What information do you get by using a bottom grab or dredge in a lake or reservoir?

Sediment properties benthic counts in benthic layer

What information do you get by using a bottom corer in a lake or reservoir?

Change in sediment over time

In order to understand where in the lake/reservoir to take samples, need to account for 3 things. Name 2 of those.

Flow patterns

Sources and Sinks

Describe how modeling data collection is an iterative process.

Collect data sometimes changes the model changes

Requireing more data

What is the primary difference between a soil scorecard and a soil sheet?

Scoresheet is more complex then a scorecard

Scoresheet required more lab tests

In the study that looked at a multitude of factors affecting soil health, what 2 specific indicators of soil health were shown

to be most important?

Organic matter and erosion

Stream ecological health is defined on the basis of comparison to what?

A healthily controlled stream

We mentioned 4 advantages of using a direct measurement of ecosystem health rather than trying to model it based on all the possible inputs (e.g., BOD, DO, nutrient levels, etc.). Describe 3 of those advantages.

question of ultimate interest

Integrates over time

Reacts to acute levels

Wide variety of life forms for different measures

What is the primary key to an ecosystem with good health or integrity?

System is stable

We mentioned 7 specific measure that tend to change as ecosystem integrity deteriorates. List 4 of those.

Biomass down

Abundance down

Diversity down

Sensitive species down

Generalists up

In order to be a good reference stream for this study stream, the reference stream should have what 2 characteristics?

Relative and un impacted

Exposed to similar species

What are the 3 questions to answer when considering using an ecological index?

Does scoring represent local conditions

Answer question

easily measured

List the 3 things we discussed that are very important in establishing a good relationship between turbidity readings and sediment concentration.

Wide variety of storms

Major toporography change

Multiple points within each storm