Moon H. Kim

A GIS approach for explanation of fish assemblage structure in a large river

Although using Geographic Information Systems (GIS) has become common in ecology, few river stud- ies incorporate this technology into examining habitat variables and use of habitat by individual fishes. Our goal was to demonstrate these GIS techniques and to test for the ability to predict fish and habitat relationships using the same data in a multivariate analysis. We collected channel bathymetry, water velocity, and streambed composition using an Acoustic Doppler Current Profiler (ADCP) deployed from a USGS boat and interfaced with a Differential Global Positioning System (DGPS) receiver, for a 10-km study reach of the Wabash River. Individual fishes were collected the following week and assigned spatial coordinates for latitude and longitude. We tested for the ability of a multi- variate technique to explain fish assemblage variation using environmental variables collected in a GIS context. We tested at which of three resolutions the environmental variables explained the highest proportion of fish assemblage variation. For this 10-km reach of the Wabash River, fish assemblages were best explained at a 10 by 10 m resolution with water velocity, water depth, river location, woody debris, and substrate composition. At a lower resolution (30 by 30 m) the same habitat variables provided similar but lower explanation of variation. However, at the highest resolution of 4 by 4 m, environmental variables provided relatively little explanation of fish assemblage structure. We suggest and recommend additional applications of a GIS approach to test temporal and spatial hypotheses of stream fish assemblage structure.

Flood-inundation maps for the Yellow River at Plymouth, Indiana

Digital flood-inundation maps for a 4.9-mile reach of the Yellow River at Plymouth, Indiana (Ind.), were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Office of Community and Rural Affairs. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage 05516500, Yellow River at Plymouth, Ind. Current conditions for estimating near-real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/in/nwis/uv?site_no=05516500. In addition, information has been provided to the National Weather Service (NWS) for incorporation into their Advanced Hydrologic Prediction Service (AHPS) flood-warning system (http:/water.weather.gov/ahps/). The NWS AHPS forecasts flood hydrographs at many sites that are often collocated with USGS streamgages, including the Yellow River at Plymouth, Ind. NWS AHPS-forecast peak-stage information may be used in conjunction with the maps developed in this study to show predicted areas of flood and forecasts of flood hydrographs at this site. For this study, flood profiles were computed for the Yellow River reach by means of a one-dimensional stepbackwater model. The hydraulic model was calibrated by using the current stage-discharge relations at the Yellow River streamgage, in combination with the flood-insurance study for Marshall County (issued in 2011). The calibrated hydraulic model was then used to determine eight water-surface profiles for flood stages at 1-foot intervals referenced to the streamgage datum and ranging from bankfull to the highest stage of the current stage-discharge rating curve. The 1-percent annual exceedance probability flood profile elevation (flood elevation with recurrence intervals within 100 years) is within the calibrated water-surface elevations for comparison. The simulated water-surface profiles were then used with a geographic information system (GIS) digital elevation model (DEM, derived from Light Detection and Ranging [lidar]) in order to delineate the area flooded at each water level. The availability of these maps, along with Internet information regarding current stage from the USGS streamgage 05516500, Yellow River at Plymouth, Ind., and forecast stream stages from the NWS AHPS, provides emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for postflood recovery efforts.

Flood-inundation maps for the St. Marys River at Fort Wayne, Indiana

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Flood-inundation maps for the White River at Newberry, Indiana

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