The Water Cycle… from clouds to sea.. from sea to clouds…

The hydrologic cycle: Water cycle as an active model Active processes –Precipitation events: rain, fog, mist, snow –Infiltration and ground and surface water flow events – eventual discharge into creeks and rivers –root adsorption –Water enters back into the atmosphere in the form of water vapor –Vapors condense, form clouds, and result in another precipitation event Animation from:

The Water Cycle on the Coast…. from sea to land …….. is a microcosm of the global cycle

The Water Cycle Globally

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage and “Residence time” in a reservoir 4. Water and climate change 5. Environmental frameworks for thinking about water

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage and “Residence time” in a reservoir 4. Water and climate change 5. Environmental frameworks for thinking about water

A Simple overview of the hydrologic cycle

Ocean Storage What percent of Earth’s water is stored in the oceans?

20,000 years ago: LOWER Sea level ~400 ft lower ) than today 120,000 years ago: HIGHER Sea level 18 ft higher than today 3M years B.P.: HIGHER Sea level 165 ft higher Does the volume of the world’s oceans ever change?

ICE AND SNOW: glaciers, ice fields, and snowfields Glacial ice covers 11% of all land Represents a large % of all freshwater Mountain snowfields are “reservoirs” for many water-supply systems –75% in Western States How much of all freshwater?

How much ground water? Ground water occurs only close to the surface

Surface Water: Lakes & Swamps & Rivers Lakes swamps account for less than 0.3% of all fresswater: - 20% is in the Great Lakes - 20% is in Lake Baikal in Siberia

Storage in the atmosphere: 0.001% Water vapor Clouds, condensed water vapor 463/f07/proj2/www/aaiordac/images/clouds.jpg

Distribution of Earth’s Water

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage in a reservoir 4. Water and climate change 5. Environmental frameworks for thinking about water

The hydrologic cycle: Active model

Processes moving water through the cycle… key Atmosphere Transport EvaporationEvaporation TranspirationTranspiration 90% 10% What percent of the water in the atmosphere comes from evaporation?

Subsurface Water movement

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage in a reservoir 4. Water and climate change 5. Environmental frameworks for thinking about water

Mass Balance: Storage, a consequence of movements Generally: Inflow (I) – Outflow (O) = Net balance Globally, we turn this around:: Outflow (O) – Inflow (I) = Net balance Evaporation (E) - Precipitation (P) E – P = Net Balance (Also called the continuity equation, conservation of mass.)

mm/day Evaporation Precipitation Evap-Precip Latitude Tropics: Convergence Subtropics: Divergence High Latitude: Convergence GLOBAL NET WATER BALANCE

Mass Balance: Storage, a consequence of movements When thinking on a local scale of land use: Inflow (I) – Outflow (O) = ± Change in storage (S) I - O = ± ∆S (Also called the continuity equation, conservation of mass.)

26 Source: NASA Earth Observatory Lake Mead: May, 2000

27 Source: NASA Earth Observatory Lake Mead: May, 2003

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage in a reservoir 4. Limitations: Water and climate change 5. Framework for thinking about water

29 Climate Change: Increases Water Vapor in the atmosphere Source: Chow et al., 1988 Atmosphere can hold more water

30 Climate Change: water balance Evaporation (E) –generally increases across the Earth Precipitation (P) – more locations specific, increases and decreases Runoff/recharge (P-E) Source: Held and Soden, 2006 CRB Model predictions of change in runoff for double CO 2 concentrations. Runoff Evaporation Precipitation

31 Climate Change – Runoff Precipitation trends controlled by wind circulation Trends intensify due to climate change: –dry areas become drier – wet areas become wetter Source: Maidment CE 394K.2 class notes, 2008

Climate Change: Modeled runoff Annual average of change in runoff compared to the global modeling average. Source: Milly et al., 2008

33 Climate Change: Water Vapor The atmosphere can “hold more water vapor” at higher temperatures This produces more clouds, which can act to both warming Therefore, increased water vapor in the atmosphere will further act to increase surface temperature and evaporation This will further increase atmospheric water vapor concentrations BUT, same amount of water, redistributed in reservoirs

Outline: 1. Reservoirs 2. Movement among reservoirs 3. Storage in a reservoir 4. Water and climate change 5. Environmental framework for thinking about water

A framework for thinking about water issues quantityquality direct human health environment

The example of Grazing

A breakdown of water use in the US, consumptive + returned Public supply, 11% from USGS, 2000 Domestic, >1% Agriculture, 36% Mining, >1% Industrial, 5% Thermoelectric, 48%

US water withdrawals and consumptive use,

Consumptive use vs. renewable water supply 1995 USGS

Irrigation in the US Total withdrawals, 2000 USGS

Water use in Illinois , excluding power generation Illinois State Water Survey

The Ogallala, the largest freshwater aquifer in the world. Saturated thickness  Regional changes in storage

Regional to global effects on precipitation: model results from deforesting Amazonia before after Teleconnections in the hydrologic cycle Jan Dec Jul Jan Dec Jul Precip, mm/yr before after Avissar and Werth (2004), Journal of Hydrometeorology Grasslands Croplands Forests

Hydrological Cycle