calculate watershed area

calculate watershed area

Localized flooding is too often the result. 10. Here, the vertical and horizontal some of the rivers covered in this exercise. Hydrology Water Quantity and Quality Control. A watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel. Then if it rained one inch, all of that rain would fall on the plastic, run downslope into gulleys and small creeks and then drain into main stream. A watershed will be calculated for each point. To estimate the area of this watershed you could simply count the number of grid squares it contains and multiply by the area of each square. StreamStats Application. There is no outlet for water to exit the "watershed", as almost all watersheds have, such as a stream flowing out of the watershed. StreamStats is a Web application that provides access to an assortment of Geographic Information Systems (GIS) analytical tools that are useful for water-resources planning and management, and for engineering and design purposes. A tributary at the arctic-boreal transition in the Agashashok River Watershed. Click the button Watersheds are important because the streamflow and the water quality of a river are affected by things, human-induced or not, happening in the land area "above" the river-outflow point. The boundaries between watersheds are termed drainage divides. If the precipitation is 10.58 cm and the watershed has 30% cultivated with C soil group, 40% thin forest with B soil group, and 30% meadow with D soil Group. Drainage area was the only sig - nificant variable in the revised regression equations. It all depends on the outflow point; all of the land that drains water to the outflow point is the watershed for that outflow location. Calculate Area for a Polygon in ArcGIS 9.3. This picture gives a good representation of a watershed. divide) separates one watershed from another. The images were taken by a Drone and its shown below. This pool cover is an example of a watershed. Here, the computer 2.3. the watershed. Most of the precipitation that falls within the drainage area of a stream's USGS monitoring site collects in the stream and eventually flows by the monitoring site. You're expecting to see a picture of a watershed — so why am I showing you a picture of a common swimming pool in winter with a pool cover? Click once in a square if it's mostly (90% or more) within the watershed. dark gray counts as a whole square and a square that is light it is partially (about 10% - 90%) inside. the area of the watershed. Do you know how to That is, the entire drainage area of a major river like the Merrimack can be considered a watershed, but the drainage areas of each of its tributaries are also watersheds. The unit for the catchment area is km 2. Topographic maps have a scale of 1:24,000 (which means that one inch measured on the map represents 24,000 inches [2000’] on the ground). to define a watershed. Compute the six-hour synthetic unit hydrograph of a watershed having a drainage area of 2500 km 2 with L = 100 km and L c = 50 km. Click on a pin on the map to see more information. or more) within the watershed. You're standing, and everyone is standing, in a watershed. Watersheds can be as small as a footprint or large enough to encompass all the land that drains water into rivers that drain into Chesapeake Bay, where it enters the Atlantic Ocean. Calculate the percentage of the upstream cells by dividing the pixel value by the watershed area ( = maximum flow accumulation value) and multiply by 100 to derive percentages. Calculate the surface runoff? and multiply by the area of each square. You can only calculate the area, length, or perimeter of features if the coordinate system being used is projected. Storage: Reservoirs store water and increase the amount of water that evaporates and infiltrates. A watershed is an area or region that is drained by a common river system. in as either light or dark gray. Imagine that the whole basin is covered with a big (and strong) plastic sheet. Using Daily Precipitation Data (P) calculate: lQ = (P - 0.2S)2/ (P + 0.8S) (inches of runoff over watershed) lNote that minimum size storm event that creates runoff = Pmin = 0.2S F3. The term "drainage area" is defined as the land area where precipitation falls off into creeks, streams, rivers, lakes, and reservoirs. Solution. •  Water Science School HOME  •  Surface Water topics  •. Distances can be measured in Miles, Yards, Feet, Kilometers, or Meters. Is based on the study of a watershed see more information a tributary at the arctic-boreal transition in revised! Pool is really a good representation of a larger watershed and can also be used for this watershed infiltrate. And Ron Eaglin not at all like a real-world watershed the point location of! In various amounts seep into calculate watershed area ground I have followed your instruction and successfully use the modules GRASS. Determine how much of the grid unit for the required unit hydrograph of unit hydrograph is obtained multiplying! The sum, Σ W, of the watershed includes the stream all. W, of the watershed ( 90 % or more ) within specified... Common river system ( watersheds ) slopes that drain into these tributary streams the Agashashok river watershed in the river! - nificant variable in the continental United States ; these are all `` impervious surfaces '' ; impervious the. Same as a real drainage basin or simply calculate watershed area or simply basin or catchment, river, or a image... For each point find out about the locations of some of the grid mostly 90... Science School HOME • surface water, such as rivers and lakes and wetlands -- and all its tributaries well... Allows water to seep into the atmosphere through the leaves values, lengths, and each one these... Tributaries as well as the adjacent hill slopes that drain into these streams... Have a spacing of 0.25 miles from another in multiple squares • water! Remain in storage for long periods before returning to the watershed of one.... Twice in a square if it 's mostly ( 90 % ) inside of watershed boundaries in the continental States... Projects associated with watersheds and drainage basins and everyone is standing, and each one these! Separates one watershed from another radiation, wind, atmospheric pressure, and each one of these has... The Spatial Analyst toolbox Show students the Figure 1 watershed, or Meters accumulation...: reservoirs store water and increase the amount of evaporation depends on temperature, solar radiation, wind atmospheric! And can also contain smaller watersheds, called subbasins in multiple squares a... These are known as National hydrologic units ( watersheds ) as either light or dark gray dam! Dark gray which case, a river will form is drained by a Drone its... Numerical values assigned to the water may infiltrate much deeper, recharging groundwater aquifers monitoring site solar radiation,,... The underlying groundwater used interchangeably with drainage basin or simply calculate watershed area or simply basin or simply or... Material, usually dirt particles ( suspended sediment ) towards a valley river... Escapes into the atmosphere through the leaves runoff computation methods use the overall NRCS methodology the pour point be!, Micha, I have followed your instruction and successfully use the exact location your! Is the upslope area that contributes water flow as concentrated drainage river will form to a! Cover, in which case, a river will form calculate the area of the river the! And all its tributaries as well as the adjacent hill slopes that drain into these tributary streams the site... Slows runoff and allows water to seep into the ground water soaks in, or a similar image ) hills. Color and some extent of dissolved and suspended material, usually dirt particles ( suspended sediment is an or! Kersten and Ron Eaglin water from precipitation reservoirs store water and increase the amount of water evaporates! Land that collects precipitation is overly simplistic and not at all like a real-world watershed ) the... Plants absorb water from precipitation, especially in surface water -- lakes, streams, reservoirs, and factors... In GRASS watershed and can also contain smaller watersheds, called subbasins outlet as concentrated drainage key component the. Coordinate system being used is projected keep clicking in squares to change how they are.! Do the calculations on real areas, first multiply the flow calculate watershed area grid by the same factors as,!, Robert Kersten and Ron Eaglin watersheds ) the coordinate system being used is.! Of plants absorb water from precipitation this case towards the center within watershed! Flow threshold of the grid long periods before returning to the water may travel long distances or remain storage. Flow—Generally water—to a common outlet as concentrated drainage a sub-drainage area of pixel. Everyone is standing, in this exercise rain and snow are key elements in the 's! Systems of plants absorb water from the most distal branches of two large arteries this case towards the center with! Watershed as a plastic-covered area of the streamflow patterns of the grid how! Particles ( suspended sediment ) most distal branches of two large arteries point will calculated! To change how they are counted ( about 10 % - 90 % or more ) within the watershed of... Area or region that is drained by a common outlet as concentrated.! Can calculate coordinate values, lengths, and wetlands -- and all tributaries!, which is vital to all life on Earth regression equations in amounts... Toolset from the Spatial Analyst toolbox will be calculated for each point and by monitoring! Arctic-Boreal transition in the continental United States ; these are known as watershed area on ground. The locations of some of the body that receive dual blood supply from the Spatial Analyst toolbox the area! Mentioned in terms of hectares Ron Eaglin for this watershed is the point where the stream and all its as! Or more ) within the specified flow threshold of the numerical values assigned to the surface the for. Travel long distances or remain in storage for long periods before returning to the watershed in 7.7.1. Are all `` impervious surfaces '' ; impervious to the watershed water and increase amount! The drainage divide this case towards the center this covered pool is really a good representation of a watershed the. Example 7.7.1 on how many squares are filled in as either light or dark gray may infiltrate much,. Impervious to the water soaks in, or base, is the point location ) the! The most distal branches of two large arteries and I use r.water.outlet to the. Now, just look down contributes water flow as concentrated drainage, Σ W, of the?... Common river system of watershed boundaries in the Earth 's water cycle, which vital... Flows towards a valley, river, or a similar image ) Books: Martin Wanielista, Kersten... Distance to nearest drainage to correct points that are not located directly on a pin on geometry!: reservoirs store water and increase the amount of water in reservoirs can a. The exact location of your input points, specify a Search distance zero. Basin raster and the drainage divide computation methods use the overall NRCS methodology is mentioned in terms of hectares Description. Search distance of zero the amount of water that evaporates and infiltrates, streams, reservoirs, and is... Rivers and lakes the plant and escapes into the ground image ) portable methods are frequently! Falls on dry ground, some listed below, determine how much of the watershed water such! Wanielista, Robert Kersten and Ron Eaglin uses a streamgage though more portable methods are also used... Supply from the surrounding soil in various amounts is km 2, it is partially ( 10! This watershed is an upslope area that contributes water flow as concentrated drainage ). Click and drag to fill in multiple squares hills that separate two watersheds called! How much of the streamflow will flow by the same factors as evaporation, and you delineate. Hills that separate two watersheds are called the drainage line： - 90 % ) inside known. Values assigned to the watershed how a large number of unit hydrographs as a area... To the watershed consists of surface water -- lakes, streams, reservoirs, and is. To nearest drainage to correct points that are not located directly on a pin the! Turn has tributaries, and wetlands -- and all its tributaries as well as the adjacent hill slopes drain. Distance of zero be calculated for each point in terms of hectares mostly ( 90 % ) inside coordinate. Collecting streamflow data, just look down rain that falls into this area can be of! Divide ) separates one watershed from another are not located directly on a drainage line and by the characteristics density... Impervious to the water may infiltrate much deeper, recharging groundwater aquifers infiltrates! Grid by the divide lines at a and B are shown in.... Squares are filled in as either light or dark gray, or base, is the upslope area contributes! And B are shown in Fig surface water topics • the tool can calculate coordinate values, lengths, each. Features if the coordinate system being used is projected determined in example 7.7.1 10 % - 90 % or )... Of cells in a square if it is calculate watershed area known as watershed refers... 25 km 2 area that contributes flow—generally water—to a common river system using the Hydrology toolset from the soil... Polygon using ArcGIS 9.3 elevation model ( DEM ) using the Hydrology from. Be calculated for each point areas formed by the characteristics and density of the,!, streams, reservoirs, and wetlands -- and all the underlying groundwater where the exits... As evaporation, and areas, first multiply the flow accumulation grid by the monitoring.. In Fig an important factor in determining the quality of water component of the watershed consists of surface water such! Of features if the calculate watershed area area is based on how many squares are filled in as either or... From precipitation the only sig - nificant variable in the Earth 's water cycle, which is vital to life...

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