Biological Objectives Tied to Physical Processes Dr. William Trush Scott McBain Arcata, CA

Outline Geomorphic-Hydrology work with Biologist Geomorphic-Hydrology work with Biologist Geomorphic-Biotic linkages Geomorphic-Biotic linkages Attributes of alluvial river integrity Attributes of alluvial river integrity Analytical techniques which include: Analytical techniques which include: Hydrograph component analysis, bar morphology, integration Reconsideration of standard techniques on assessing impacts of dams Reconsideration of standard techniques on assessing impacts of dams

Historical Perspective Need to have a good understanding of how the system historically functioned, both physical components and biotic components Need to have a good understanding of how the system historically functioned, both physical components and biotic components –Evaporation –Precipitation –Different Species –Variety of hydrologic regimen –Variable geology

Conceptual Framework Supply /Control Process Form Habitat Biota Watershed Inputs Water, sediment Fluvial Geomorphic Processes Transport, deposition Geomorphic Attributes Channel morphology (size, shape, slope) Habitat Structure, Complexity In stream aquatic habitat, woodlands Biotic Response Abundance and distribution of native/exotic species For all take note of: Human land use and flow regulation, natural disturbance For all take note of: Human land use and flow regulation, natural disturbance

Bottom-Up vs. Top-Down Bottom-Up- Biologist Bottom-Up- Biologist –Start under water, without understanding the history and geomorphic processes. They never challenge the base line of the river. Top-Down- Geologist Top-Down- Geologist –Start above water need to consider a biological stand point. Have to approach both ways- integration is the key Have to approach both ways- integration is the key

Processes You Need To Go Through… Data Data Spend time getting historical condition, land and species Spend time getting historical condition, land and species Conceptual model Conceptual model Objectives Objectives

Priority Hypothesis Geomorphic Geomorphic –Dam has eliminated upstream sediment supply, decreasing in-channel coarse sediment storage Salmonid Salmonid 1)Spawning gravel supply has been decreased 2)Spawning habitat is limiting salmonid production

Attributes of Alluvial Rivers Historical Model of “Trinity River” Historical Model of “Trinity River” –Look at conceptual models to identify key process and formation that maintained the ecosystem –The process of developing the attributes is most important and different for every river

Attributes of Alluvial Rivers cont. 1) Spatially complex channel morphology (migrate, meander, side channels) 2) Flows and water quality are predictably variable (Trends in river that are consistent per year during certain times) 3) Bed moves frequently (1-2 year) 4) Bed scour and fill (5-10 year) 5) Balance fine and coarse sediment 6) Channel migrates/avulsion

Attributes of Alluvial Rivers cont. 1) Floodplains (oxbows, fine sediment dep.) 2) Channel Resettling floods (20-50 yrs. Large scale geomorphic change) 3) Plant communities 4) Fluctuating ground water table (wetlands and animals)

Channel Complexity Very Complex Very Complex Point bars (plants), scours, oxbows, sheer zones/pools (fish), side channels, variable particle size Point bars (plants), scours, oxbows, sheer zones/pools (fish), side channels, variable particle size

Create and Maintain Channel Morphology Hydrograph Hydrograph –Print our every hydrograph for the periods of record, develop hypothesis –Conduct water year analysis to evaluate inter- annual flow variability (wet year vs. dry year) –Intra-annual flow variability with in water year, evaluate changes relate geomorphic processes and life history of key biota –Link biota to hydrology

Different water years = Different ecological functions ConditionHydrologicGeomorphicEcological ExtremelyWet Large winter floods, large snowmelt runoff peak- melting occurs through June Channel avulsion, migration, bed load transport, bed scour, lots of fine sediment, floodplain scour and dep. Vegetation removal, woody debris, greater migration up stream, high juvenile salmon growth rates, low salmon out migration mortality Normal Moderate winter floods, moderate snowmelt/runoff, moderate base flows Moderate: Channel migration, bed load transport, floodplain, fine sediment Minor veg. removal, mod salmon migration access up stream, low salmon out migration mortality CriticallyDry Small winter floods, miner snowmelt, short duration of runoff, higher water temp No channel migration, no gravel transport Veg. lower in channel, no scour, low migration up stream, mod. Water temp- stress mortality to salmon, moderate salmon out migration mortality

Other Biological Hotspots Sediment deposition Sediment deposition Channel complexity (bars, side channels) Channel complexity (bars, side channels) Riparian vegetation Riparian vegetation Spawning areas Spawning areas Amphibian egg laying locations Amphibian egg laying locations Large wood accumulation Large wood accumulation

Suggestions Historical perspective to understand how the system naturally worked Historical perspective to understand how the system naturally worked Hypotheses on how project changes the components of the system (Geomorphic-Biotic) Hypotheses on how project changes the components of the system (Geomorphic-Biotic) Use top/down and bottom/up approach with lots of coordination between physical scientist and biologist Use top/down and bottom/up approach with lots of coordination between physical scientist and biologist No river is the same, nor does every dam have the same impacts No river is the same, nor does every dam have the same impacts

Case Study 1 Overview of hydrology, geomorphology, and channel morphology of the Clavey River Overview of hydrology, geomorphology, and channel morphology of the Clavey River Develop hypotheses Develop hypotheses Illustrate some conceptual models and analytical tools useful for access dam- related impacts to steep bedrock rivers Illustrate some conceptual models and analytical tools useful for access dam- related impacts to steep bedrock rivers

Summary of Changes Substantial loss of flow volume Substantial loss of flow volume Substantial reduction on flood magnitude and frequency Substantial reduction on flood magnitude and frequency Constant year found base flows Constant year found base flows Loss of coarse sediment supply Loss of coarse sediment supply Reduction or loss of fine sediment Reduction or loss of fine sediment Downstream tributaries and valley walls still contribute fine and coarse sediment to channel Downstream tributaries and valley walls still contribute fine and coarse sediment to channel

Potential Impacts Accumulation of fine sediment and gravels in channel Accumulation of fine sediment and gravels in channel Riparian and upland vegetation intrusion Riparian and upland vegetation intrusion Abandoned side channels and ponded areas Abandoned side channels and ponded areas Reduction of residual pool volume by gravel-boulder filling Reduction of residual pool volume by gravel-boulder filling And… And…

Potential Impacts Reduced magnitude, duration, and frequency of bed mobility of alluvial features Reduced magnitude, duration, and frequency of bed mobility of alluvial features Reduced coarse sediment storage immediately downstream of the dam Reduced coarse sediment storage immediately downstream of the dam