Surface Water Chapter 9

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

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

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

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

Fate of water 2) Rate of precipitation  Heavy: soil clumps together closing pores Fills up ground to quickly and water becomes runoff  Light: allows water to gently slide through Less erosion

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

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

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

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

Mississippi Watershed

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

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

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

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