1. Overview of Watershed Systems
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Overview of Watershed Systems
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2. Module Outline What is a Watershed? Watersheds in Idaho
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Module Outline
What is a Watershed?
Watersheds in Idaho
Principles of Watershed Hydrology
Natural Watershed Functions and Features
In this particular module, we are going to cover these 5 topics, beginning first with what may be the most fundamental concept you’ll learn all day.

3. What is a Watershed? Presentation
First off, what is a watershed? Let’s see if we can get some help…

4. Presentation
What is a Watershed?
What do you think your neighbors and friends would say if you asked them what a watershed is. Do you think you’d get some of the same responses as we saw in the video? Probably so…
Well, the fisherman and the lady in the last clip were correct. A watershed is an area of land that water flows across, through, or under as it drains to a stream, river, lake or ocean. The important thing to remember is that a watershed is an area of land that catches rain and other types of precipitation and then directs it to neighboring bodies of water. And each body of water has its own watershed.
The cool thing is that you’re sitting in a watershed right now. All of the land on the Earth is in some way part of a watershed and all watersheds are connected across the landscape.
In essence, a watershed is like one big bathtub. Just as the picture says – we’re all in the same bathtub. Kind of a scary thought if you think about it. But it’s true. So a bathtub is a good representation of a watershed because the tub’s drain represents the outlet of the watershed or the mouth of stream, river, lake, ocean. And the watershed boundary is represented by the tub's rim.
An area of land that water flows across, through, or under on its way to a stream, river, lake, ocean or other body of water.
A watershed is like
one big bathtub...

5. WATERSHED Presentation
This is a diagram of a typical watershed. The boundary between any two watersheds is called a divide as you can see here. Watershed divides are defined by the elevational highpoints (the highest point of an area of land, such as the top of a hill or mountain) that surrounds a body of water. Any water that falls outside of a watershed divide will enter another watershed and will flow to another point. So, all of the land that drains water to a common water body is considered to be in the same watershed.
WATERSHED

6. DIVIDE DIVIDE Presentation
Here is an aerial view of what watershed divides actually looks like. And if anyone is wondering, this picture is not from Texas…Any precipitation that falls inside this watershed boundary will drain to this river system and eventually to the ocean. Any precipitation that falls outside of this particular watershed boundary will enter a different watershed and will flow to another common drainage point.
From this picture it’s easy to see how all watersheds are connected across the landscape. Each of these smaller streams and drainages that you see here each have their own small watersheds that drain water into this larger central river here...that has its own larger watershed. This river then drains to a larger river with its own even larger watershed and so on and so forth until it reaches the ocean. So, you can look at a watershed at many different scales as you see here in this diagram…

7. WATERSHED Presentation
Watersheds are nested systems and include smaller watersheds called sub-watersheds, and larger collections of watersheds called sub-basins and river basins. We can look at a watershed from any of these different scales, the smallest being the stream itself, all the way up to a scale as large as a river basin, which is simply a collection of many different watersheds.
WATERSHED

8. What Do Watersheds Look Like?
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What Do Watersheds Look Like?
Watersheds come in many different shapes and sizes:
Can include farmland, rangeland, small towns, or big cities.
Can have hills, mountains, or be nearly flat.
Can range from a few acres to millions of square miles.
So what do watersheds actually look like? Well, watersheds come in many different shapes and sizes and have many different features. They can have hills or mountains or can be nearly flat. They may include farmland, rangeland, small towns, or big cities. Watersheds can range in size from a few acres to as large as the Mississippi River Basin, which drains 1.2 million square miles.

9. Where Are Watersheds Found?
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Where Are Watersheds Found?
We find watersheds EVERYWHERE.
ALL land area is part of a watershed.
We ALL live in a watershed.
Where do we find watersheds? WE FIND THEM EVERYWHERE. All land area is part of a watershed so we all live in a watershed. If you write nothing else down from today’s training or remember nothing else….you want to remember these 3 statements.

10. Module Outline Watersheds in Idaho What is a Watershed?
Presentation
Module Outline
What is a Watershed?
Watersheds in Idaho
Principles of Watershed Hydrology
Natural Watershed Functions and Features

11. Texas River and Coastal Basins
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Texas River and Coastal Basins
15 major river basins and 8 coastal basins
191,000 miles of streams and rivers!
As we discussed previously, watersheds can be found at many different scales. Because Texas is such a huge state, it literally has thousands of watersheds and sub-watersheds. To make things a bit easier to understand, we often lump several watersheds together that all eventually drain to the same large river system such as the Brazos or the Guadalupe River, for example. And these collections of watersheds are called river basins.
So, Texas has 15 major river basins and 8 coastal basins. Within these basins, there are over 191,000 miles of streams and rivers!

12. Rivers of Idaho
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13. Presentation
Major Watersheds
HUC Watersheds:
Hydrologic Unit Codes

14. Reynolds Creek Experimental Watershed – in Idaho
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Reynolds Creek Experimental Watershed – in Idaho

15. Module Outline Principles of Watershed Hydrology What is a Watershed?
Presentation
Module Outline
What is a Watershed?
Watersheds in Idaho
Principles of Watershed Hydrology
Natural Watershed Features and Functions
So far, we’ve been talking a lot about watersheds, but clearly, water is a major part of any watershed. So let’s talk more about water and how it cycles in a watershed.

16. Principles of Watershed Hydrology
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Principles of Watershed Hydrology
Hydrology = “study of water”
Nearly 75% of the Earth’s surface is covered with water.
Water is constantly cycling via an endless process known as the water cycle, or the hydrologic cycle.
The study of water is called hydrology. Watershed hydrology, then, is the study of water as it interacts with various parts of a watershed, including the land, the sea and the sky.
Water is hugely important to everyone and everything on this planet. Nearly 75 percent of the Earth’s surface is covered by water, all of which has been around since the Earth was formed several billion years ago.
Earth's water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Who’s heard of the water cycle before?

17. The Water Cycle EVAPORATION CONDENSATION PRECIPITATION RUNOFF
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The Water Cycle
EVAPORATION
CONDENSATION
PRECIPITATION
RUNOFF
Since the water cycle is truly a "cycle," there is no beginning or end. But, it does have some major components that include evaporation, condensation, precipitation, and runoff.
And the cool thing about the water cycle is that water can change states between solid, liquid, and gas at various places in the water cycle, and these processes can happen in the blink of an eye or over millions of years.

18. Presentation
Evaporation occurs when the water in lakes, oceans, rivers and streams (surface water) is heated by the sun and converted to a gas called water vapor. Evaporation also occurs in trees and plants through a process called evapotranspiration. In this process, liquid water evaporates from plant leaves and stems and is converted to water vapor.
Condensation is the process by which water vapor returns to its original liquid state. It typically occurs in the atmosphere when warm air rises, cools, and, as a result, loses its capacity to hold water vapor. Excess water vapor then condenses to form clouds. Condensation in the atmosphere may also be visible as fog, mist, dew or frost, depending on the physical conditions of the atmosphere.
Precipitation occurs when condensed water in clouds—which is too heavy to remain suspended in the air—falls to the Earth as rain, sleet, hail or snow. Precipitation is a major component of the water cycle and it is the primary source of the fresh water found on the surface of the Earth.
Gravity Recovery and Climate Experiment, University of Texas

19. Presentation
Let’s take a look of the water cycle in action. NOTE: YOU MUST HAVE AN INTERNET CONNECTION FOR THE MOVIE TO WORK.

20. Where Does Precipitation Go?
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Where Does Precipitation Go?
It can run off
What happens to precipitation once it lands on the Earth? Well, several factors affect where it goes, and generally, it can take one of 5 different pathways:
1. It can run off into streams and rivers and become surface water that eventually makes its way to the ocean. Runoff occurs when the rate of precipitation exceeds the rate at which the water can be absorbed into the soil. Runoff also occurs when water falls onto an impermeable surface, such as a parking lot or a sidewalk, where it can’t easily be absorbed into the soil.

21. Where Does Precipitation Go?
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Where Does Precipitation Go?
It can be absorbed by plants and used for photosynthesis and other biological processes
 2. It can be absorbed by plants and utilized in various biological processes such as photosynthesis.

22. Where Does Precipitation Go?
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Where Does Precipitation Go?
It can infiltrate through the soil surface and percolate downward to groundwater aquifers
3. It can filter through the soil surface and percolate downwards into groundwater aquifers. An aquifer is an underground storage place for water that consists of layers of rock and sand.
Percolation

23. Where Does Precipitation Go?
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Where Does Precipitation Go?
It can evaporate
4. It can evaporate - both from the surface of the Earth or as it falls from the sky.

24. Where Does Precipitation Go?
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Where Does Precipitation Go?
It can be stored in ice caps, glaciers, lakes, reservoirs and other surface bodies of water
5. It can be stored in ice caps and glaciers (which have the ability to store frozen water for thousands of years), lakes, ponds, reservoirs, and other surface bodies of water.

25. Land Use/Land Cover Changes
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Land Use/Land Cover Changes
Land use = how land is used by humans:
Land cover = biological or physical features of land:
Agriculture
Forests
Industry
Grasslands
Urban
Agricultural fields
Residential
Rivers, lakes
Recreation
Buildings, parking lots
So, what affects where precipitation goes once it lands on the surface of the Earth? A lot of it has to do with how the land itself is used and hence, what kind of surface the precipitation lands on as it falls from the sky. Land use refers to how the land is used by humans. And that can include anything from agricultural purposes to recreational purposes. The point is, is that when we change how the land is used, we often change the type of land cover – that is the biological or physical features of the land - associated with that land use too. For example, when a new housing development or retail center is built, grasslands and forests are converted to a new land cover type – pavement and concrete. And you can imagine how these changes might affect how water naturally cycles in a watershed.
In addition to this, land use and land cover changes can also greatly affect the natural watershed features and functions which we’ll talk about next and perhaps even more importantly, they can greatly affect the quantity and quality of our water resources which Mark, Matt, and Nikki will get into in a little while.
Water is a universal solvent, affected by all that it comes in contact with: the land it traverses, and the soils through which it travels. The important thing about watersheds is: what we do on the land affects water quality for all communities living downstream.

26. Module Outline Natural Watershed Functions and Features
Presentation
Module Outline
What is a Watershed?
Watersheds in Texas
Principles of Watershed Hydrology
Natural Watershed Functions and Features
Now, let’s talk more about how watersheds actually work. What are they here for, and what do they do?

27. Natural Watershed Functions
Presentation
Natural Watershed Functions
Hydrological Functions
Ecological Functions
Water capture
Provide diverse sites for biogeochemical reactions
Water storage
Provide habitat for plants and animals
Water release
As we’ve already found out today, watersheds are associated with creeks, streams, rivers, and lakes; but they are much more than just that. A watershed is a highly evolved series of processes and functions that convey, store, distribute, filter, and utilize water to sustain terrestrial and aquatic life in both obvious and unseen ways.
A watershed has five primary functions – 3 of which are related to hydrology and 2 of which are related to ecology. The 5 functions include:
Let’s take a closer look at each one of these important watershed functions.

28. Hydro Function #1: Water Capture
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Hydro Function #1: Water Capture
H2O is transferred from atmosphere and is “captured” in the soil
H2O can then infiltrate through soil surface and percolate downward into soil profile
The first hydrological function of a watershed is water capture.
Water capture is the process by which water from the atmosphere is captured or stored in the soil. Water capture occurs via infiltration and percolation. Infiltration is the movement of moisture from the atmosphere directly into the surface of the soil. Percolation is the downward movement of water through the soil profile.
Several factors affect infiltration and percolation rates, including the soil type (primarily texture and depth), topography and climate, land use and land cover.

29. Hydro Function #2: Water Storage
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Hydro Function #2: Water Storage
Water is stored in the pores (air spaces) between soil particles in the soil profile.
Department of Primary Industries, Australia
clay/silt particles
Once water is captured in the soil, it is stored in the pores between soil particles which brings us to the second hydrological function of watersheds – water storage.
The amount of moisture that a soil can hold depends on the soil’s depth, texture, structure and pore size. Pore size is probably one of the most important physical features of a soil. It controls water, air movement and storage.
For example, much less water can be stored in sandy soils than in clayey soils. This is because sandy soils are made up of large soil particles with large pores in between these particles. Water drains more easily through large pores than through small pores.

30. Hydro Function #2: Water Storage
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Hydro Function #2: Water Storage
Not only does the kind of soil affect water storage in a watershed, but the kinds, amounts and distribution of vegetation on the ground also greatly affect the amount of water stored in a watershed. An area of land covered with vegetation will capture more water and hold it for a longer period of time compared to an area of land that doesn’t have any vegetation at all.

31. Hydro Function #2: Water Storage
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Hydro Function #2: Water Storage
This diagram illustrates that very point. In the built environment, when we remove vegetation, we remove nature's mechanisms for storing and cleaning water. Asphalt surfaces on rooftops, roads, and parking lots keep water from reaching soils. Instead, the water runs off the roads, streets, and buildings and into nearby waterways. Whereas in a naturally vegetated area, more water infiltrates into the soil rather than runs off the soil surface.

32. Hydro Function #3: Water Release
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Hydro Function #3: Water Release
Water moves underground, through the soil profile, or across the land surface as runoff
The third hydrological function of a watershed is water release. Water is released from a watershed when it moves through the soil profile to seeps and springs, or across the land surface as runoff, and ultimately into streams and rivers that flow to oceans. Water is safely released when it moves out of the watershed without causing adverse environmental impacts.

33. Natural Watershed Functions
Presentation
Natural Watershed Functions
Hydrological Functions
Ecological Functions
Water capture
Provide diverse sites for biogeochemical reactions
Water storage
Provide habitat for plants and animals
Water release
Now, let’s talk about the ecological functions of watersheds.

34. Eco Function #1: Biogeochemical Reactions
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Eco Function #1: Biogeochemical Reactions
Biogeochemical cycling = the biological, physical and chemical transformations of nutrients that are found in soil, water, and air.
Very complex interactions that help maintain plant and microbial communities.
The first ecological function of a watershed is to provide diverse sites for biogeochemical cycling.
Biogeochemical cycling refers to the biological, physical and chemical transformations of nutrients that are found in soil, water and air. Many of these interactions are quite complex, but they are very important in maintaining proper watershed function. Nutrients such as nitrogen, sulfur, phosphorus, carbon and hydrogen, and organic materials containing these nutrients, are constantly undergoing biological, physical and chemical reactions with the surrounding environment. These processes help maintain the plant and microbial communities found along water bodies in a watershed. These plant and microbes, in turn, fuel additional reactions and biogeochemical cycling. These communities also help maintain the global atmosphere through a complex cycle in which carbon is trapped in plant biomass, preventing its release into the atmosphere as carbon dioxide, a greenhouse gas.
University Corporation for Atmospheric Research (UCAR)

35. Eco Function #2: Habitat
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Eco Function #2: Habitat
Habitat = “home”
Watersheds provide critical habitat for all kinds of plants and animals
The second ecological function of a watershed is to provide habitat for plants and animals.
Habitat refers to the natural home of a plant or an animal. A healthy habitat contains everything a species needs to survive—food, water, cover, and a place to raise young. Our human habitat might include our home, our place of work, and the grocery store. The habitats of plants and animals, on the other hand, might include a small puddle in a backyard or a massive rainforest on another continent. Because different living things have different needs for food, water and cover, each kind of plant and animal requires a specific kind of habitat. Healthy and abundant habitat is critical not only to the survival of plants and animals, but also to the overall function of a watershed.

36. Natural Watershed Features
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Natural Watershed Features
A healthy watershed has some natural features that help it carry out the essential hydrological and ecological functions we just discussed.
These features include uplands, floodplains, riparian zones and water bodies. These features are intimately connected and work together to ensure that a watershed is functioning properly.

37. Watershed Feature #1: Upland
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Watershed Feature #1: Upland
Upland = area of land at a higher elevation above a water body
Forms watershed boundaries, or divides
Provides habitat, stabilizes soil, minimizes soil erosion, filters surface runoff
An upland is an area of land located at a higher elevation above a water body. Uplands typically form watershed boundaries, or divides that we discussed at the beginning of this presentation. The upland areas of a watershed are important habitat for mammals, birds, reptiles and amphibians. Upland vegetation stabilizes the soil surface, minimizes surface erosion, and filters and retains dissolved and suspended matter carried by surface water runoff from the surrounding land.

38. Watershed Feature #2: Floodplain
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Watershed Feature #2: Floodplain
Floodplain = flat area of land surrounding a water body that is subject to periodic flooding
Holds excess water after precipitation events, filters out sediment, provides habitat, and recreation for humans
The floodplain is the flat area of land surrounding a body of water that is subject to periodic flooding. After heavy rainfalls, the floodplain holds excess water, allowing it to be slowly released into the river system or seep into groundwater aquifers. Floodplains also help to filter out sediment from floodwaters, thereby keeping it out of water bodies. Floodplains often support an abundance of aquatic and are often used as recreation areas.

39. Watershed Feature #3: Riparian Zone
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Watershed Feature #3: Riparian Zone
Riparian = “of the river”
The non-cultivated, vegetated land that touches and immediately surrounds a body of water
Often includes wetlands which help to:
Stabilize slopes and streambanks
Filter pollutants
Maintain proper water temps.
Supplement nutrients
Provide habitat for plants/animals
The third important feature of a watershed is the riparian zone.
The word riparian means “of the river.” The riparian zone is the non-cultivated, vegetated land that touches and immediately surrounds a stream, river, lake or other body of water. This riparian zone often includes wetlands which are areas of land that are regularly saturated with water for at least part of the year and that contain vegetation adapted to living in saturated conditions.
The upper portion of Bastrop Bayou is bordered by forests and wooded glens. The middle section is fringed mostly by prairies and fields. The lower section of Bastrop Bayou flows through an extensive complex of coastal wetlands.
Wetlands and other components of the riparian zone perform vital functions that help maintain the health of the watershed. Riparian zones help to:
Stabilize watershed slopes and streambanks. The roots of trees and plants hold streambank soil in place so that ground is not lost to erosion.
Filter pollutants. The vegetation in the riparian area traps sediment and other pollutants, and absorbs nutrients from the watershed before they can reach the water.
Maintain proper water temperatures within the stream or river. Trees and plants hanging over the water shade it and help keep it cool all summer (this is critical to fish life, as many fish can’t live with a rise in temperature of even a few degrees).
Supplement nutrients. As leaves and insects fall into the water they provide food for animals living in the stream.
Provide habitat and food for wildlife. Many birds (Great Blue Herons, Kingfishers, Eagles, Osprey, etc.) and other animals rely on vegetation near water for their homes and resting places.
Provide a “transitional zone” from bank to floodplain to watershed slope. This is critical for flood mitigation, as it gives floodwater a place to slow down and soak in or enter the stream with less energy.
Provide transitional zone from bank to floodplain to watershed slope

40. Watershed Feature #4: Water Body
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Watershed Feature #4: Water Body
Any stream, river, pond, lake estuary, ocean, or other body of water
Water bodies can be flowing (lotic) or non-flowing (lentic)
Flow of water greatly affected by topography, slope, soils and vegetation
Last, but certainly not least, a major feature of a watershed is the water body itself where all of the water that falls in the watershed drains to.
A water body refers to any stream, river, pond, lake, estuary, or ocean. Water bodies can be flowing (lotic) systems (streams and rivers) or non-flowing (lentic) systems (ponds and lakes).
The flow of water in these systems, particularly in rivers and streams, is greatly affected by the natural features of the watershed including the topography, slope, soils and vegetation. For example, the natural meanders, or curves, in a stream or river help slow down the flow of water and control flash flooding. A severe, rapid release of water will occur in straight channels with little resistance to water movement. As mentioned earlier, vegetation helps protect streambanks by absorbing energy from flowing water.

41. Closing thoughts… ALL parts of a watershed are EQUALLY important.
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Closing thoughts…
ALL parts of a watershed are EQUALLY important.
Proper care of the uplands, floodplains, riparian zones, and water bodies keeps the watershed functioning properly.
The ideal condition will keep most water where it falls, reduce runoff, and allow for moderate streamflows.
Some important closing thoughts to remember. All parts of a watershed are equally important. The upland and floodplain zones capture and store water, while the riparian zone is the primary release mechanism for the watershed. Proper care of the uplands, floodplains, riparian zones and water bodies keeps the watershed functioning properly. The ideal condition will keep most water where it falls, reduce runoff, and allow for moderate streamflows.

42. Key Points to Remember…
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Key Points to Remember…
A watershed is an area of land that water flows across or under as it drains to a body of water.
Watersheds are everywhere!
Watersheds are used for many different purposes.
Watersheds are a critical component of the water cycle, which is an endless process that cycles water and distributes it across the Earth.
Watersheds have hydrological and ecological functions.
Watersheds have natural features that help them perform their hydrological and ecological functions.
If you get nothing else out of this presentation, get these key points.

43. Presentation
Thanks to Jennifer Peterson Texas Watershed Steward Program