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Water: Healthy Watersheds

Hydrologic/Geomorphic Assessments

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Healthy Watersheds Home Concept, Approach & Benefits Aquatic Biodiversity Aquatic Resource Surveys Biotic Condition Assessment Framework Examples of Assessments Habitat and Biodiversity Conservation Hydrology/Geomorphology Green Infrastructure Conservation Approaches & Tools Where You Live Integrated Assessments Landscape Condition Local Land Use Ordinances Publications Outreach Tools Natural Disturbance Regimes Nonpoint Source Pollution River Corridor Protection

Hydrology and geomorphology are intricately linked through erosional and depositional processes that create a dynamic equilibrium in healthy watersheds. The dynamic equilibrium of the physical system establishes the dynamic equilibrium of the biological system, thus maintaining the ecological integrity of the system as a whole. Reference conditions are important for hydrologic/geomorphic assessments of aquatic ecosystems.

Ecological Limits of Hydrologic Alteration (PDF) (4 pp, 227K, About PDF) Exit EPA Disclaimer
The Ecological Limits of Hydrologic Alteration (ELOHA) is a new framework offering a flexible, scientifically defensible compromise for broadly assessing environmental flow needs when in-depth studies cannot be performed for all rivers in a region. ELOHA is especially useful for state-level assessments. Follow the link to read case studies of the ELOHA methodExit EPA Disclaimer

Hydroecological Integrity Assessment Process
The Hydroecological Integrity Assessment Process is a framework and set of tools developed by the USGS to characterize the 5 major components of the Natural Flow Regime. As streamflow is a “master variable” in aquatic ecosystems, this assessment provides valuable information regarding the ecological integrity of the system.

Watershed Assessment of River Stability and Sediment Supply (WARSS)
WARSSS is a technical procedure developed by Dr. David L. Rosgen for water quality scientists to use in evaluating streams and rivers impaired by excess sediment.


Characteristics and Classification of Least Altered Streamflows in Massachusetts
USGS presents a method for developing a hydrologic classification of rivers in Southern New England. This method identifies the degree of alteration of streamflows.

New Jersey Hydroecological Integrity Assessment Software (PDF) (80 pp, 1.69MB, About PDF)
The Hydroecological Integrity Assessment Process recognizes that streamflow is strongly related to many critical physiochemical components of rivers, such as dissolved oxygen, channel geomorphology, and water temperature, and can be considered a “master variable” that limits the disturbance, abundance, and diversity of many aquatic plant and animal species.

The Massachusetts Sustainable-Yield Estimator (10 pp, 376K, About PDF) Exit EPA Disclaimer
A decision-support system to assess surface-water resources in Massachusetts.

A Regional-scale Habitat Suitability Model to Assess the Effects of Flow Reduction on Fish Assemblages in Michigan Streams (50 pp, 5.4MB, About PDF) Exit EPA Disclaimer
An ecological classification of river segments, catchment size, and July river temperature is used to assess the effects of reduced baseflow on fish species and assemblages. The method is useful for identifying streams with healthy baseflows and streams vulnerable to ecological disruption as a result of reduced baseflow. The method provides a framework for developing regional environmental flow standards across Michigan rivers that parallels ELOHA.

Minnesota DNRs Stream Habitat Program Exit EPA Disclaimer
The Minnesota Department of Natural Resources assesses shape, flow, connectivity, biology, and water quality of its 90,000 miles of rivers and streams to provide a holistic view of the state’s water resources.

Vermont Stream Geomorphic Assessment Exit EPA Disclaimer
Vermont has produced a River Corridor Protection Guide to explain the science behind river corridors and offer detailed procedures and tools for corridor delineation. Vermont uses the river corridor in its work with landowners and town, state, and federal agencies as a science-based river and riparian land use planning, conservation, and management tool to avoid conflicts between human investments and the dynamics of rivers.

MesoHABSIM Exit EPA Disclaimer
A physical habitat simulation model that simulates the consequences of ecosystem alteration due to changing spatial distributions of physical attributes of a river and variations in flow. MesoHABSIM builds upon the PHABSIM model.

Proper Functioning Condition (PFC) (PDF) (58 pp, 1.91MB, About PDF)
PFC tool is a qualitative watershed assessment tool developed by BLM that assesses proper functioning of riparian-wetland areas and the condition of these areas based on observations focusing on the physical condition of the channel and riparian-wetland area. PFC is used widely in the West as a quick assessment tool to determine the stream’s stability and identify management practices that need to be changed in order to improve channel conditions. The basic questions PFC answers is whether or not at stream channel and its wetland-riparian area can withstand high flow events, e.g., 5-, 10-, and 20-year events without significant loss of integrity. PFC can be used to identify riparian-wetland systems for protection.

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