Watersheds and Hydrology What’s Water Got to Do with It? More water moves through ecosystems than any other material The materials that it carries and deposits and the energy that it expends are major drivers in shaping the contour of the land and the habitat availability/suitability for organisms. A resource that humans cannot live without Slide discussing water and ecosystems

Watersheds and Hydrology Learning Objectives Where do we find water? What is the hydrologic cycle? How many dimensions does a stream have? 4 How do we characterize stream water? 5 What do we want to know about stream flow?

Where do we find water? Question 1 Slide listing objectives for session 9, river as habitat

Global distribution of water

Global distribution of freshwater Water Storage Reservoir Percent (%) of total Percent freshwater Oceans 96.5 Ice and Permanent Snow 1.74 68.7 Groundwater 1.7 30.1 Lakes 0.013 0.91 Soil Moisture including permafrost 0.023 0.26 Atmosphere 0.001 0.04 Streams, Rivers, Swamps 0.036 Biosphere 0.0001 0.003 Igor Shikomanov “world fresh water resources in Gleick 1993 Water Crisis (Oxford Press)

Watersheds and Hydrology Where do we find water? What is the hydrologic cycle? How many dimensions does a stream have? 4 How do we characterize stream water? 5 What do we want to know about stream flow?

Question 2 What is the hydrologic cycle? Precipitation Interception Infiltration Evaporation Transpiration Runoff Ground water

Watersheds and Hydrology Where do we find water? What is the hydrologic cycle? How many dimensions does a stream have? 4 How do we characterize stream water? 5 What do we want to know about stream flow?

How many dimensions does a stream have? Question 3 How many dimensions does a stream have?

Question 3 How many dimensions does a stream have? Longitudinal (upstream to downstream) Lateral (bank to bank and valley wall to valley wall) Vertical (water surface to bed to hyporheic to ground water) Temporal (time: seconds to millennia)

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

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 gradients Riffle is an area of rapid flow over coarse substrate (rocks) whereas the pool is a slower flowing stretch with finer substrate

Lateral Patterns There are also some predictable changes laterally The stream has its low flow channel, the low point of which is 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 Thalweg

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

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

Vertical dimensions Velocity changes with depth in stream channel Diagram by:Eric G. Paterson Department of Mechanical and Nuclear Engineering The Pennsylvania State University

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

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.

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

Watersheds and Hydrology Where do we find water? What is the hydrologic cycle? How many dimensions does a stream have? 4 How do we characterize stream water? 5 What do we want to know about stream flow?

What are the major physical, chemical, Question 4 What are the major physical, chemical, and biological components used to characterize water quality? Slide outlines the objectives for session 10

Selected Important Habitat Factors Light Substrate Temperature Oxygen levels Flow velocity Food availability pH Nutrient and sediment regimes Organic input and transport Toxics and other pollutants Biological communities

Influence of temperature on growth rates 1.0 Midges Daily Growth Rate (mg/mg/day) 0.5 Blackflies Daily growth rates as a function of temperature for three aquatic insects in Georgia. Modified from Benke 1993. Mayflies 8 16 24 32 Temperature C Modified from Benke 1993

Watersheds and Hydrology Where do we find water? What is the hydrologic cycle? How many dimensions does a stream have? 4 How do we characterize stream water? 5 What do we want to know about stream flow?

What do we want to know about stream flow? Question 5 What do we want to know about stream flow? Magnitude - how much? Frequency - how often? Timing - when? Duration - how long? Rate of change – how fast? Slide of ways to characterize flow, emphasis on magnitude.

Mean Monthly Flows Juanita Creek Water Years 2005-2009

Mean daily flow (cfs) Juanita Creek Water Year 2010 Oct May

Mean May Discharge Juanita Creek

Hourly vs 15 Minute Measurements

Mean Daily Flow Juanita Creek (cfs)

15 minute flows Juanita Creek May 27-29, 2004

Unregulated Regulated

How much water is enough? Depends on who or what is using the water Historically managed for minimum flows (what is the minimum flow that keeps fish alive) Legal issue of water rights complicates situation

Stream flow functions Medium where aquatic organisms live and propagate Needs vary by species and life stage Focusing flow requirements on single species can result in unintended harm to other species Plays a role in stream temperature and oxygen levels

Stream flow functions 2. Provides the forces that create and maintain in-channel and off-channel habitat, riparian patch communities, etc. New channel formation Wood recruitment and distribution Sediment recruitment and transport Removal of fines

Stream flow functions 3. Rejuvenates floodplain soils and vegetation and recharge groundwater Maintain connectivity with hyporheic zones Redistribute soil and nutrients to floodplain forest Distribute seeds and prepare seed beds

Examples of where to locate national data for watersheds and streams Watershed data EPA Surf your watershed http://www.epa.gov/surf/ Climate data (national and international) http://www.ncdc.noaa.gov/oa/ncdc.html Climate data (Washington) http://www.wrcc.dri.edu/summary/climsmwa.html

Examples of where to locate national data for watersheds and streams Stream data- quantity and quality USGS Water Resources Data http://water.usgs.gov/data.html Soils data http://soils.usda.gov/ Aquatic biologic indicators http://www.epa.gov/bioindicators/

Take – home messages Flow regimes play a major role in habitat Land-use alters flow paths and storage components and hence, flow regimes Effects vary with spatial and temporal scales Research on which aspects of flow are most critical to various biotic responses are in progress Don’t forget the basic processes involved Summary slide of land use change and ecological effects.