Hydrology River Ecosystems and Humans

Dimensions of river ecosystems Longitudinal Lateral Vertical Temporal 2

Longitudinal Changes in Streams Certain characteristics of streams change predictably from upstream to downsteam –Channels become wider –Flow becomes slower, but greater in volume –Streams become deeper 3

Longitudinal Changes – Reach Scale Longitudinal changes are also observed at shorter scales than the entire river length We call this shorter scale the “reach” scale One example of reach scale changes is the pool- riffle pattern found in many streams draining areas with medium gradient Riffle is an area of rapid flow over coarse substrate (rocks) whereas the pool is a slower flowing stretch with finer substrate Path of flow - thalweg 4

Lateral Patterns There are also some predictable changes laterally The stream has a low flow channel; the fastest flow is called the thalweg The stream has banks which define its frequent flow limit The stream has a floodplain which defines its flow limit on less frequent events, annual or lesser frequency 5

Lateral Patterns Some streams and rivers will have a single dominant channel while others will have a network of interwoven channels 6

Lateral Features As rivers increase in size they may develop a complex floodplain system 7

Vertical dimensions Velocity changes with depth in stream channel Discharge (Q) = VA Diagram by:Eric G. Paterson Department of Mechanical and Nuclear Engineering The Pennsylvania State University 8

Vertical Features Hyporheic (below stream) inter- actions Exchanges occur with groundwater just below the stream 9

Lateral and Vertical Patterns In many large alluvial valleys, creatures that live in ground water and hyporheic water can be found in the subsurface water kilometers from the stream. In other words the stream extends well beyond its channel. 10

Temporal dimension Stream flow changes Second by second Hourly Daily Monthly Seasonally Annually Milleniumly 11

Selected Important Habitat Factors Substrate Temperature Oxygen levels Flow velocity Food availability pH Nutrient and sediment regimes Organic input and transport 12

How are species distributed in space and time? -- Environments contributing to riverine biodiversity Surface waterSubsurface waterRiparian system Streams Springs Lakes Hyporheic Zone Ground Water Confined Reaches Unconfined Reaches 13

River  Floodplain Edge Spatial distribution of species across a floodplain (lateral dimension) (Ward and Tockner 2001 fig. 9.3) Species Richness Eg. Fish Snails, slugs, mussels, Dragonflies, damselflies Frogs, salamanders, toads Aquatic plants 14

How do humans affect watersheds and the hydrologic cycle ? 15

Human caused disturbances Agriculture Timber harvest Mining Urbanization Introduction of exotic species Harvesting of fish and wildlife 16

Land use/cover and vegetation PhysiographyClimate Landscape controls Nutrient Inputs Solar energy and Organic input Regime Gross reach morphology Habitat Forming Processes Species assemblages Stream Morphology and Conditions Biodiversity Habitat complexes and conditions e.g., pools, riffles, temperature, etc. Sediment and Hydrologic Regime Modified from Roni et al

Physical, chemical, and biological components related to water quality Light Temperature Dissolved ions Suspended solids Nutrients and gases Toxics such as metals and pesticides/herbicides Biological features PPCPs (Pharmaceuticals & Personal Care Products) 18

Photos by R.S. Lindsay Photo by Carrie Inman Agriculture 19

FORESTRY 20

Aggregate Mining In-channel mining In-channel and floodplain mining Photos by M. Kondolf 21

URBANIZATION 22

Forestry, agriculture and urbanization Remove trees and other vegetation Reduce organic matter delivery Build roads 23

Large storage in soil, channel and valley floor Recharge Natural cleaning Pollutant wash off No recharge Rapid flow limited storage Slow flow NaturalDeveloped Reduced soil storage Limited infiltration Precipitation 24

Floods and Urbanization surface runoff vs. infiltration natural land cover vs. urban area 25

How do we manage watershed? Dept of Natural Resources Regulations U.S. Forest Service Regulations Clean water act Endangered Species Act Total Maximum Daily Loads (TMDLs) 26

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Take Home Messages Understand the interactions between land use/land cover and components of the hydrologic cycle Be able to describe what is typically measured in watersheds and why 30

Hydrology Report ~ 2-3 pages due May 25 individually Include: Name, Date, Title Introduction Methods Results and Discussion (w tables) Conclusions Appendix (if needed for raw calculations) 31