Monday, May 09, 2016

The Interactive Watershed Map


FernLeaf Interactive has created an interactive map which allows you to view over 100,000 watershed regions. The map shows the topological relationships between the USGS level 12 hydrologic units for the entire United States.

The Watersheds Map allows you to visualize watershed regions throughout the USA. As you mouse-over the map it automatically updates to show upstream areas in red and downstream areas in blue. You can click on the map at anytime to freeze the map view (click on the map again to unfreeze & re-enable the dynamic loading of the watershed data).

The map also includes a dynamic URL facility. This means that you can share a watershed view highlighted on the map simply by cutting and pasting the map's current URL.


Hydro Hierarchy is a map of the largest rivers in the United States and their monthly river flows. Select a river segment on the map and you can view a chart of its 2014 monthly river flow.

The horizontal red line on the bar chart represents the ten year mean monthly flow, which means you can compare each month's river flow to its yearly average. The 2014 drought means that on a lot of river segments many of the months will be below the ten year average.

The radial chart to the left of the map is a hierarchical representation of the stream network. If you mouse over to the center of the chart you can view river terminations at the ocean or international borders.


Hydro Hierarchy only visualizes rivers and streams with a Strahler stream order classification of four or greater. Andrew Hill has created a map of all United States rivers in which the rivers are colored by the direction of flow. The U.S. Rivers Colored by the Direction they Flow map shows the colored river locations on a black background to create a visually striking map of the United States.

The map uses data from Nelson Minar's Vector River Map, which in turn uses river flow data from NHDPlus. Andrew has also used the same river data to create another beautiful map. Rivers with Rainfall. This map shows U.S. rivers and rainfall in the last hour. The rain data comes from a National Weather Service data feed.
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