Users' manual for the Hydroecological Integrity Assessment Process software (including the New Jersey Assessment Tools)

Abstract

This manual is a user’s guide to four computer software tools that have been developed for the Hydroecological Integrity Assessment Process. 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. Applying the Hydroecological Integrity Assessment Process involves four steps: (1) a hydrologic classification of relatively unmodified streams in a geographic area using long-term gage records and 171 ecologically relevant indices; (2) the identification of statistically significant, nonredundant, hydroecologically relevant indices associated with the five major flow components for each stream class; and (3) the development of a stream-classification tool and a hydrologic assessment tool. Four computer software tools have been developed. • The Hydrologic Index Tool calculates 171 biologically relevant hydrologic indices using daily and peak flow records. The indices are then used for a regional (State) stream classification analysis. The program is designed to import U.S. Geological Survey mean daily and peak flow discharges from the National Water Information System databases. • The National Hydrologic Assessment Tool is based on a hydrologic classification of streams which used 420 gaging stations across the contiguous United States. The National Hydrologic Assessment Tool has six stream classes identified. The program is used to establish a hydrologic baseline (reference time period), to establish environmental flow standards, and to evaluate past and proposed hydrologic modification. This is accomplished by using flow statistics, trend analysis, and 10 primary stream class specific indices that address the five major components of flow. • A New Jersey stream classification tool classifies any stream within the State into one of the four stream types found in the State. The four classes of streams identified in New Jersey are characterized by the relative degree of skewness of daily flows (low = stable flow, high = flashy flow) and frequency of low-flow events (low = high base flow; high = low base flow). Thus, streams belonging to stream class A are semiflashy with moderately low baseflow, class B streams are stable with high base flow, class C streams are moderately stable with a moderately high base flow, and class D streams are flashy with a low base flow. • The New Jersey Hydrologic Assessment Tool is used to establish a hydrologic baseline (reference time period), establish environmental flow standards, and evaluate past and proposed hydrologic modifications of streams in New Jersey. This is accomplished by using flow statistics, trend analysis, and 10 primary stream class specific indices that address the five major components of flow.