Rivers throughout the United States create geological features that fascinate many people, whether for work or play. Rivers also pose a threat to many cities each year, as spring rains and melting snow fill these rivers beyond their capacity, causing them to overflow their banks; flooding the surrounding area. Rivers can cause flooding, but they also provide many benefits to society. One of the most notable is hydroelectric power, which often leads to the construction of dams on a river. A dammed river creates a reliable location for adventure companies looking to create whitewater rafting businesses that use the flow of the river through rapids and scenic views to create a thrill for seeking clients adventure. A river or "stream, ribbons of water confined to channels, or troughs dug in the ground" (Marshak, 2009) are formed from a drainage network or "a set of watercourses interconnected” which form tributaries. (Marshak, 2009). The amount of water that flows through a stream is its flow rate. Flow measurement takes the width and depths or cross-section of a river along with the downstream velocity to obtain a numerical value for the amount of water moving downstream. (Marshak, 2009) As a river flows downstream, it frequently encounters obstacles and changes in the river bed that form “rapids, particularly turbulent waters with a rough surface. Rapids also form where the channel suddenly narrows or when its slope changes, suddenly speeding up the water. » (Marshak, 2009) These changes in the dynamics of river flow create the rapids sought by modern-day thrill-seekers. a ledge in the middle of a river or on the side can obstruct the flow of the river. ("International...... middle of article...... pid formation is caused by the slope of a river. "The slope of a river is the rate at which it loses water “altitude throughout its course. This loss determines the slope of the river and, to a large extent, its flow” (“International Scale of”, 2010), this means that a river which loses a foot of. elevation over a distance of one hundred feet or with a slope of one percent will flow more slowly than a river which loses twenty-five feet of elevation over the same section of one hundred feet or a slope of twenty-five percent which will have. a much higher flow. Works Cited International River Difficulty Scale (2010, June 11). Whitewater (2011)./