DELINEATING THE HYPORHEIC ZONE

ALISSA JAMES

INTRODUCTION

How have the fields of ecology and hydrogeology attempted to delineate the hyporheic zone?

It is hard to define something we cannot immediately see.

Different definitions of the hyporheic zone (HZ) exist, based upon the field of science concerned

Importance within hydrology?

HYPO = UNDER/ BENEATHRHEO = TO FLOW

MEANWHILE IN GREECE…

FAUNAL HABITAT

A distinct habitat was detected and named the ‘hyporheic biotope’.

This habitat was identified within the interface between surface and groundwater (Orghidan, 1959).

Identification of a large and diverse collection of fauna (Danielopo, 1989).

A REFUGE

Biocenosis between organisms (Sabater and Vila, 1990).

A temporary refuge for organisms in times of physical and biological adversity (Stanford and Ward, 1988).

An ‘ecotone’ (Williams, 2010)

DELINEATION ATTEMPTS In-situ microbe calculations (Hynes, 1974)

and correlation with concentrations of DO. The ‘hyporheic corridor’ concept (Stanford

and Ward, 1993). Slower level of biological processes then

that of the surface (Gibert et al, 1994) Complex and temporally variable distribution

of ecology within the hyporheic zone.

DEFINING THE HYPORHEIC ZONE

Combining the factors of groundwater flow/exchange with populations of hyporheic invertebrates (Stanley and Boulton, 1993).

?

THE GROUNDWATER SYSTEM

The hyporheic zone represents an area with increased mixing of surface and groundwater.

Dynamic and interesting zone

An important site of solute retention, metabolism and mineralization (Bencala, 1993).

Considers geomorphological and sedimentological structure

DELINEATION ATTEMPTS

Quantification within hydrogeology has been attempted through identification of hyporheic depth or length of flow path.

But also, in a more detailed manner, through consideration of the amount of water present through the surface and groundwater components (Triska et al).

METHODS OF DELINEATION Examined at a wide range of scales;

from riffles to whole drainage basins. Delineated through exchange processes

that occur.

INTERCONNECTIVITY

Hyporheic

Zone

Ecology

Faunal Assemblage

Residence Times

Hydrogeology

Groundwater-Surface

Interactions

Interconnected Processes

Physical Properties

CONCLUSIONS

Inter-system connectivity, used to be considered as distinct entities.

Heterogeneity; varied spatially and temporally

The characteristics of running water are controlled by the interaction with their surroundings.

A WORKING DEFINITION The zone below and adjacent to a streambed

in which water from the open channel exchanges with interstitial water in the bed sediments (White, 1993). It is the zone around a stream in which fauna characteristic of the hyporheic zone are distributed and live (Danielopo, 1989). It is a zone in which groundwater and surface water mix (Orghidan, 1959, Triska et al, 1993). The boundaries of the hyporheic zone vary in time and space

REFERENCES Bencala, K. E., 1993, A perspective on stream-catchment connections; Journal of the North

American Benthological Society, p.44-47. Danielopo D.L.,1989,Groundwater fauna associated with riverine aquifers: Journal of North.

American Benthological Society, v.8, p18-35. Gibert J, Danielopo D.L and Stanford J.A. (eds),1994, Groundwater Ecology: San Diego, Academic Orghidan, 1959, Ein neur Leben-sraum des unterirdischen Wassers: der hyporheische Biotop: Arch.

Hydrobiology; v. 55, p392-414 Sabater F. and Vila P.B., 1991, The Hyporheic Zone considered as an ecotone: Oecologia Aquatica,

v.10, p.35-43 Stanford J.A. and Ward J.V., 1993, An ecosystem perspective of alluvial rivers: connectivity and the

hyporheic corridor, Journal. North. American. Benthological Society, v. 12, p. 48-60 Stanley, E. H., and Boulton, A. J. ,1993, Hydrology and the distribution of hyporheos: perspectives

from a mesic river and a desert stream: Journal of the North American Benthological Society, p. 79-83.

Triska F.J, Duff, J.H, and Avanzino R.J., 1993, The role of water exchange between a stream channel and its hyporheic zone in nitrogen cycling at the terrestrial-aquatic interface: Hydrobiologia, v. 251, p.167-184.

Ward, J. V.,1989, The four-dimensional nature of lotic ecosystems: Journal of the North American Benthological Society, v.8, p.2-8.

White D.S., 1993, Perspectives on defining and delineating hyporheic zones: Journal of the North American Benthological Society v. 12, p.79-83.

Williams D.D, Febria C.M, and Wong J.C.Y., 2010, Ecotonal and other properties of the Hyporheic Zone: Fundamentals. Applied. Limnology., Arch. Hydrobiol. v.176-4, p. 349–364