New Jersey Water Science Center

Development of the Hydroecological Integrity Assessment Process for Determining Environmental Flows for New Jersey Streams

Prepared in cooperation with the New Jersey Department of Environmental Protection

By Jonathan G. Kennen, James A. Henriksen, and Steven P. Nieswand

Scientific Investigations Report 2007-5206

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The natural flow regime paradigm and parallel stream ecological concepts and theories have established the benefits of maintaining or restoring the full range of natural hydrologic variation for physiochemical processes, biodiversity, and the evolutionary potential of aquatic and riparian communities. A synthesis of recent advances in hydroecological research coupled with stream classification has resulted in a new process to determine environmental flows and assess hydrologic alteration. This process has national and international applicability. It allows classification of streams into hydrologic stream classes and identification of a set of non-redundant and ecologically relevant hydrologic indices for 10 critical sub-components of flow. Three computer programs have been developed for implementing the Hydroecological Integrity Assessment Process (HIP): (1) the Hydrologic Indices Tool (HIT), which calculates 171 ecologically relevant hydrologic indices on the basis of daily-flow and peak-flow stream-gage data; (2) the New Jersey Hydrologic Assessment Tool (NJHAT), which can be used to establish a hydrologic baseline period, provide options for setting baseline environmental-flow standards, and compare past and proposed streamflow alterations; and (3) the New Jersey Stream Classification Tool (NJSCT), designed for placing unclassified streams into pre-defined stream classes. Biological and multivariate response models including principal-component, cluster, and discriminant-function analyses aided in the development of software and implementation of the HIP for New Jersey. A pilot effort is currently underway by the New Jersey Department of Environmental Protection in which the HIP is being used to evaluate the effects of past and proposed surface-water use, ground-water extraction, and land-use changes on stream ecosystems while determining the most effective way to integrate the process into ongoing regulatory programs. Ultimately, this scientifically defensible process will help to quantify the effects of anthropogenic changes and development on hydrologic variability and help planners and resource managers balance current and future water requirements with ecological needs.





Purpose and scope

Study area description

Technical Advisory Committee Activities

Comparison of 10 Environmental Flow Methods

Examination of Two Environmental Flow Methods

Development of the Hydroecological Integrity Assessment Process




Hydrologic Index Tool

Stream Classification Processes

Selection of Streams and Period of Record

Clustering of Streams

Development of the New Jersey Stream Classification Tool (NJSCT)

Application of the Hydroecological Integrity Assessment Process

Establishing a Hydrologic Baseline

Examples of New Jersey Hydroecological Assessment Tool (NJHAT) Application

Example A

Example B

Developing Environmental Flow Standards

Summary and Conclusions


References Cited

Appendix 1. Members of the Technical Advisory Committee

Appendix 2. Review of seminal ecological concepts

Appendix 3. Distinctive characteristics of the four stream classes in New Jersey

Appendix 4. Stream class and characteristics of gaging stations representing relatively unimpaired basins used to classify New Jersey streams

Appendix 5. Verification results for the 171 hydrologic indices

Appendix 6. Hydrologic indices with the largest absolute loading for each of the statistically significant principal component axes for each stream type in the nine sub-components of the flow regime

Appendix 7. Definitions of the 171 hydrologic indices

Download: PDF of SIR2007-5206 (3.2Mb)

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