These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 1

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5 Basic conservation equation: The amount of a conservative quantity entering a control volume during a defined period, minus the amount of the quantity leaving the volume during the time period, equals the change in the amount of the quantity stored in the volume during the time period

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 6 Drainage basin Boundary of a Drainage basin is referred to as a divide All of these terms are related to a point (cross-section) in a stream. The location of the cross-section that defines the watershed is determind by the purpose of the analysis

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8 Precipitation - water released back to earth from saturated region of atmosphere - Evaporation -increases in air and water temperatures, wind and solar radiation all increase evaporation - Transpiration - water used by plants in photosynthesis and released to the atmosphere by plants Evapotranspiration - - includes both water that evaporates from soil and plant surfaces and the water that moves out of the soil profile by plant transpiration -

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 9 Infiltration - entry of water into the soil - - rates depend on soil water content, texture, density, organic matter content, hydraulic conductivity, and porosity - Percolation and Groundwater recharge - - water that moves beyond the root zone is referred to as deep percolation (groundwater recharge)

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 10 Interflow - soil water flow - Groundwater flow - Runoff and overland flow - RO = what comes out of a basin - - where R.I. > I.C. depressions will fill creating depression or surface storage. As this continures overland flow will ensue -

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 11 Water balance equation P + Gin - (Q + ET + Gout) = 0 Runoff (hydrologic circulation) total amount of liquid (or solid) water leaving basin if we make the assumption that Gin is negligible (watersheds are topographically defined and ground-water flow is driven by gravity) then RO ≈ P - ET

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 12 Hydrologic Production the amount of water actually produced “in” the basin Storage - - error associated with this is minimized by 1) using long measurement periods and 2) selecting the time of the beginning and end of the measurement period such that storage values are likely to be equal (e.g. USGS water year begins October 1)

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 13 In some systems (lakes, rivers, groundwater bodies) outflow rate increases with the amount of storage: so e.g. in a linear reservoir no natural reservoirs are linear, but this is often a powerful first approximation Storage has two main effects: 1. Decreases the relative variability of outflows relative to inflows 2.

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 14 Residence time The average length of time that a “parcel” of water spends in the reservoir. holds true only when q and i are equal (average change in storage is zero) Water in the ocean has a residence time of about 3000 years in streams about 17 days

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 15

These notes are provided to help you pay attention IN class. If I notice poor attendance, fewer notes will begin to appear on these pages 16 From Dingman, 1994