Distribution and biogeochemical impact of small water bodies in the United States.  We have identified about 2.6 million water bodies in 30-meter-resolution USGS land use/land cover (NLCD) data. About half of these are single-pixel features. A sample of 1:24,000 USGS quadrangles, which show features as small as 5 meters across, suggests a total number of water bodies >3 times greater than shown in the NLCD data. They are most heavily concentrated in the eastern Great Plains and the southeastern states, where they reach densities of over 3 per square kilometer. While this analysis does not separate natural from artificial water bodies, it is clear that the overwhelming majority are of human origin—predominantly farm ponds. These features locally elevate evaporation, divert and delay downstream water flow, and modify groundwater interactions and local biotic habitats. They apparently intercept about as much eroded soil as larger, better-documented reservoirs. Collaborators include Steve Smith (CISESE, Ensenada, Mexico), Bob Buddemeier (Univ. of Kansas), and Rich Sleezer (Emporia State Univ.).  Project web site.

Sediment and nutrient fluxes in an agricultural landscape.  This work focuses on movement of sediment and nutrients through the hydrologic system, and the linkages between these fluxes and reservoir ecosystems.  We have been monitoring streamflow and sediment transport in the 260 km2 Upper Four Mile Creek watershed in southwestern Ohio since 1992. The watershed is >85% agricultural, and land management practices dominate material fluxes.  Changing agricultural practices such as conservation tillage, nutrient management, and livestock management practices are having dramatic effects on sediment and nutrient yields from the landscape, with significant decreases in phosphorus and sediment fluxes.  These changes in stream water quality are having significant effects on the ecology of Acton Lake.  The project is currently funded by a NSF Long-Term Research in Environmental Biology (LTREB) grant.  Collaborators include Mike Vanni and Maria Gonzalez. Stream flow data are available for streams draining to Acton Lake -- contact Bill Renwick.

Ponds and Reservoirs in Southwestern Ohio.  Three counties in southwest Ohio--Preble, Butler, and Hamilton--represent a gradient of land use and topography within which the effects of artificial impoundments on the hydrologic landscape and biogeochemical cycling can be studied.  Preble County, in the north, is relatively flat and agricultural.  Hamilton County, in the south, is relatively hilly and urban (metropolitan Cincinnati) with large forest areas.  Butler County is intermediate in topography and land use.  In the last century several reservoirs and over 4,000 small ponds and several larger reservoirs have been built in the three-county region.  Ponds are most common in Butler County, which has a large portion of land that is neither ideal for agriculture nor dense urban settlement.  Ponds built in the mid-20th century served mostly agricultural purposes, but today most pond construction is associated with suburban development.  Ponds are dynamic features on the landscape.  The number of ponds has grown steadily, but of 835 ponds that existed in the three-county region in the mid-1950s over 90% had disappeared by 2000.