Surface Water Chapter 9 Surface water movement Water

Surface Water Chapter 9

Surface water movement: Water Cycle l Earths water supply is constantly recycled

Surface Water Movement l 1) Runoff ¡Water flowing down slope along Earth’s surface or seep into the ground l Run off speed determined by slope of the hill ¡Ends up in a stream or lake, evaporate, or accumulate into puddles

Movement l Seep into ground ¡Ground must have large enough pores – loose soil l Evaporate

Fate of water: Run off or Seep l Certain characteristics will determine whether not water will either seep into or become runoff l 1) Vegetation ¡Vegetation allows for loose soil ¡ Loose soil allows water to enter ground ¡ Gardeners do not pack their soil

Fate of water l 2) Rate of precipitation ¡Heavy: lsoil clumps together closing pores l. Fills up ground to quickly and water becomes runoff ¡Light: lallows water to gently slide through l. Less erosion

Fate of Water l 3) Soil Composition ¡Effects the waters holding capacity ¡Decayed organic matter (humus) l. Creates the pores in soil – Increases retain ability ¡Minerals l. Clay – fine mineral which clump together • Few Spaces l. Sand – large pores

Fate of Water l 4) Slopes ¡Steep: allows for high runoff & little absorption ¡Little: low runoff and high absorption

Formation of Stream systems l Runoff l Surface water flows in thin sheets and eventually collects in small channels l Runoff increases, channels widen and become deeper and longer l Channels fill up again each time with rain l Channel can become a stream

l Water sheds: ¡drainage basin ¡Land where all water drains into l Divide ¡High land area that separates watersheds

Mississippi Watershed

Stream Load l All the materials that the stream carries l Solution ¡Material that has been dissolved ¡Depends on area where the steam runs through ¡Erosion of rocks and dirt

Stream Load l Suspension ¡Small particles held up by the turbulence of stream ¡Clay, silt, sand ¡Depends on volume and velocity of water l Bed Load ¡Turbulence of water pushes heavy things ¡Pebbles and cobbles ¡Larger velocity – large objects ¡B/c of abrasion, rocks are smooth

Stream Velocity & Carrying Capacity l Discharge = width x depth x velocity (m) (m/s) l As discharge increases so does carrying capacity

Floods l Water fills over the sides of a stream banks l Floodplain: broad flat area of land that extends out from streams for excess flooding