11 6 15 and 11 9 15 Dr Frauenfeld a Water is constantly circulating through the atmosphere hydrosphere lithosphere and Chapter 9 Water Resources I Hydrologic Cycle biosphere b More than 97 of water is in the ocean i Ocean dominates evaporation c More than 70 of the world is covered by ocean i Ocean also dominates precipitation i Precipitation Evaporation and transpiration more water arrives than leaves i Evaporation Precipitation i Each year the land gains 8 of water while the oceans lose 8 of water ii Water lost by the ocean is replaced by runoff which balances the process d Over Land e Over Water f Advection g h i Atmospheric Moisture Balance Source Evapotranspiration Ocean Evapotranspiration Land Precipitation Ocean Precipitation Land Input 86 14 Output 78 22 Total 100 100 11 6 15 and 11 9 15 Dr Frauenfeld j Actual Evaporation ACTET i Evaporation 1 Open Water 2 Soil 3 Vegetation Surfaces ii Transpiration 1 Plants release water evaporates 2 Cooling mechanism iii Global Areas of Evapotranspiration Higher where there are the most plants and where it is the wettest k Potential Evapotranspiration POTET i The amount of water that would evaporate transpire under optimum moisture conditions when there is adequate precipitation and soil moisture supply 1 What that means maximum ET that could theoretically occur ii Determined by 1 Latitude solar angle length of day the more sunlight the more ET 2 Temperature II Water Budget a Components of the hydrologic cycle vary greatly from one location to another i Precipitation vs POTET Supply Demand 11 6 15 and 11 9 15 Dr Frauenfeld b Surface Water Budget c Annual River Runoff high amounts of runoff where the most precipitation happens 11 6 15 and 11 9 15 d Soil Moisture Storage Dr Frauenfeld Gravitation water only happens with saturation percolated down e Soil Moisture Availability f Water Balance Equation 11 6 15 and 11 9 15 Dr Frauenfeld g Sample Water Budget Kingsport TN Can t get surplus till soil is at its field capacity POTET will always peak in the summer because it follows the insolation curve III Drought a Less precipitation than expected or needed i Compared to climate normal ii Demand exceeds supply b A naturally recurring feature of the global climate system c Four Main Types i Meteorological less precipitation than expected ii Agricultural longer lasting less water than needed for agriculture iii Hydrological start dipping into the water reserves ground water lakes reservoirs etc not enough water for day to day activities iv Socioeconomic not enough water to survive d Lake Mead i 1983 1229 ft ii 2009 1086 ft IV Ground Water a Largest Potential Freshwater Source b Linked to surface supplies recharge i Accumulates over millions of years i 22 of freshwater ii Technically the cryosphere ice and glaciers is 77 but it is not really available 11 6 15 and 11 9 15 Dr Frauenfeld c Groundwater Storage in the U S d High Plains Aquifer 11 6 15 and 11 9 15 e Global Water Withdrawal Dr Frauenfeld f Global Water Scarcity
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