Chapter 9 Section 1 Surface Water Movement PDF

11/13/2024 Chapter 9 Section 1 How can surface water move weathered materials? 1  11/13/2024 How does a floodpl...

11/13/2024 Chapter 9 Section 1 How can surface water move weathered materials? 1  11/13/2024 How does a floodplain develop? The Water Cycle The water cycle, also referred to as the hydrologic cycle, is a never-ending, natural circulation of water through Earth’s systems. Copyright © McGraw-Hill Education Surface Water Movement 2  11/13/2024 The Water Cycle Water molecules move continuously through the water cycle following many pathways: they evaporate from a body of water or the surface of Earth, condense into cloud droplets, fall as precipitation back to Earth’s surface, and infiltrate the ground. Copyright © McGraw-Hill Education Surface Water Movement Runoff Water flowing downslope along Earth’s surface is called runoff. A number of conditions determine whether water on Earth’s surface will infiltrate the ground or become runoff. Copyright © McGraw-Hill Education Surface Water Movement 3  11/13/2024 Runoff Soil composition The physical and chemical composition of soil affects its water-holding capacity. Copyright © McGraw-Hill Education Surface Water Movement Runoff Soil composition Soil that has open surface pores allows water to infiltrate. The particle size that makes up a soil helps determine the pore space of the soil. Large grain size Fine grain size Mixed grain size Copyright © McGraw-Hill Education Surface Water Movement 4  11/13/2024 Runoff Rate of precipitation If the rate of precipitation exceeds the rate of infiltration, the water will become runoff. Copyright © McGraw-Hill Education Surface Water Movement Runoff Vegetation Vegetation can slow the rate of runoff of surface water. Raindrops are slowed when they strike the leaves of trees or blades of grass, and they trickle down slowly. Copyright © McGraw-Hill Education Surface Water Movement 5  11/13/2024 Runoff Slope Water from precipitation falling on slopes flows to areas of lower elevation. The steeper the slope, the faster the water flows. Copyright © McGraw-Hill Education Surface Water Movement Stream Systems Some surface water flows in thin sheets and eventually collects in small channels, which are the physical areas where streams flow. Copyright © McGraw-Hill Education Surface Water Movement 6  11/13/2024 Stream Systems Tributaries Rivers that flow into other streams are called tributaries. Copyright © McGraw-Hill Education Surface Water Movement Stream Systems Watersheds and divides All of the land area whose water drains into a stream system is called the system’s watershed. A divide is an elevated land area that separates one watershed from another. Copyright © McGraw-Hill Education Surface Water Movement 7  11/13/2024 Stream Systems Watersheds and divides The watershed of the Mississippi River includes many stream systems, including the Mississippi, Missouri, and Ohio Rivers. The Continental Divide marks the western boundary of the watershed. Copyright © McGraw-Hill Education Surface Water Movement 8  11/13/2024 Stream Load The material that a stream carries is known as stream load. Stream load is carried in three ways. Copyright © McGraw-Hill Education Surface Water Movement 9  11/13/2024 Stream Load Materials in suspension Suspension is the method of transport for all particles small enough to be held up by the turbulence of a stream’s moving water. Copyright © McGraw-Hill Education Surface Water Movement Stream Load Bed load A stream’s bed load consists of sand, pebbles, and cobbles that the stream’s water can roll or push along the bed of the stream. Copyright © McGraw-Hill Education Surface Water Movement 10  11/13/2024 Stream Load Materials in solution When water runs through or over rocks with soluble minerals, it dissolves small amounts of the minerals and carries them away in the solution. Copyright © McGraw-Hill Education Surface Water Movement Stream Carrying Capacity The ability of a stream to transport material, referred to as its carrying capacity, depends on both the velocity and the amount of water moving in the stream. Copyright © McGraw-Hill Education Surface Water Movement 11  11/13/2024 Stream Carrying Capacity Discharge is the measure of the volume of stream water that flows past a particular location within a given period of time. Copyright © McGraw-Hill Education Surface Water Movement Stream Carrying Capacity Stream discharge is the product of a stream’s average width, average depth, and the velocity of the water. Copyright © McGraw-Hill Education Surface Water Movement 12  11/13/2024 Floods A flood occurs when water spills over the sides of a stream’s banks onto the adjacent land. The broad, flat area that extends out from a stream’s bank and is covered by excess water during times of flooding is known as the stream’s floodplain. Copyright © McGraw-Hill Education Surface Water Movement Floods When rivers overflow their banks, the floodwater deposits sediment. Over time, sediment accumulates along the edges of a river, resulting in natural levees. Copyright © McGraw-Hill Education Surface Water Movement 13  11/13/2024 Floods Flood stages When the water level in a stream rises higher than its banks, the river is said to be at flood stage. The flooding of a small area is known as an upstream flood. Heavy accumulation of excess water from large regional drainage systems results in downstream floods. Copyright © McGraw-Hill Education Surface Water Movement Flood Monitoring and Warning Systems In areas that are prone to severe flooding, warning systems, such as those established by the National Weather Service and the U.S. Geological Survey, are the first step in implementing emergency management plans. Copyright © McGraw-Hill Education Surface Water Movement 14 11/13/2024 15