A simple, rapid method for mapping bathymetry of small wetland basins

Many tools exist for determining and mapping the bathymetry and topography of aquatic systems, such as freshwater wetlands. However, these tools often require time-consuming survey work to produce accurate maps. In particular, the large quantity of data necessary may be prohibitive for projects where determining bathymetry is not a central focus, but instead a necessary step in achieving some other goal. We present a method to produce bathymetric surface maps with a minimum amount of effort using global positioning system receiver and laser transit survey data. We also demonstrate that this method is surprisingly accurate, given the small amount of data we use to generate the bathymetry maps.

The Hi content of compact groups of galaxies

The Hi content of Hickson Compact Groups in the southern hemisphere is measured using data from the Hi Parkes All-Sky Survey (HIPASS), and dedicated observations using the narrow band filter on the Multibeam instrument on the Parkes telescope. The expected Hi mass of these groups was estimated using the luminosity, diameter, and morphological types of the member galaxies, calibrated from published data. Taking careful account of non-detection limits, the results show that the compact group population that has been detected by these observations has an Hi content similar to that of galaxies in the reference field sample. The upper limits for the undetected groups lie within the normal range; improvement of these limits will require a large increase in sensitivity.