Once Upon a River

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Why We Love It

This map application is deceptively simple upon first glance, but rewards your curiosity with every mouse click. As you explore each river you find rich details and stunning patterns. Move your cursor over a river to see its network and a month-by-month chart of water flow for 2014. We also love this feature: Put your cursor at the center of the radial chart, and slowly pull downward to navigate a river from where it meets the ocean or international border.

Why It Works

On this map, every pixel is data. It does not have unnecessary ornamentation, not even the traditional basemap, borders, and text labels. Now the data and its patterns take center stage. This interactive map shows us how river flow changes throughout the year, and how the timing of maximum flow changes based on geographic region. This same technique could be used to map rail, logistics, shipping, or telecommunications.

Important Steps

Create a river network from the USGS National Hydrographic Dataset.

Adjust features to ensure connectivity, direction of flow, and generalization for use in small scale mapping.

Attribute the features with flow data, from USGS WaterWatch website.

Download the source code for this application and configure it to the river network you created.



You need a river network, represented as connected linear features, each with a direction of flow and volume of flow.


Validate that all network segments are connected, and that direction of flow is correctly indicated. Volume of flow is joined to the features.


It will take several days, depending on the size and complexity of the source data and experience with network datasets.

Fast Performance


The fast performance of the application is due to the connectivity information being pre-processed and made available in a JavaScript file.



The connectivity allows the application to show upstream and downstream flow statistics from any point on the map or graph.

More Information

Map Author

Richie Carmichael

Richie Carmichael

@KiwiRichie | LinkedIn

A 13-year veteran at Esri and the Applications Prototype Lab. Trained as a New Zealand land surveyor. Striving for world peace one map at a time.

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