SMALL ARTIFICAL WATER BODIES: A NEGLECTED BUT IMPORTANT FACTOR IN WATER SUPPLY AND ENVIRONMENTAL QUALITY R. W. Buddemeier 1,2, R. O. Sleezer 3, D. P. Young 1, S. Egbert 2,4, F. J. deNoyelles 4,5, X. Zhan 1, W. H. Renwick 6, and S. V. Smith 7 1. Kansas Geological Survey 2. Dept. of Geography, KU 3. Emporia State Univ. 4. Kansas Biological Survey & KARS 5. Dept. of Ecology & Evolutionary Biology, KU 6. Miami Univ. (Ohio) 7. CICESE (Mexico) Acknowledgements: Technical contributions: Z. Andereck,, M. Dunbar, B.N. Mosiman, P. Taylor, M. Houts, J. Vopata, E. Wilson Funding: Kansas NASA EPSCoR Program (KNEP) – US NASA and KTEC

Relatively large dams and reservoirs have been extensively studied because of their effects on water and sediment budgets at scales from regional to global. Cumulatively, these artificial water bodies are an important factor in biogeochemical fluxes at global scales– -- in addition to providing water supplies that profoundly influence patterns of development, population and land use

Small impoundments, which are many times more numerous, have received little attention. Recent studies* have improved estimates of both inventory and the importance of small water bodies, and have been the basis for a KNEP-sponsored project reported here. *Smith, S. V., Renwick, W. H., Buddemeier, R. W., and Crossland, C. J Budgets of soil erosion and deposition for sediments and sedimentary organic carbon across the conterminous United States. Global Biogeochemical Cycles 15(3): Smith, S. V., Renwick, W. H., Bartley, J. D., and Buddemeier, R. W Distribution and significance of small, artificial water bodies across the United States landscape. The Science of the Total Environment 299:21-36 Renwick, W.H., S.V. Smith, J.D. Bartley and R.W. Buddemeier, in press. The Role of Small Impoundments in the Sediment Budget of the Conterminous United States. Geomorphology.

What is the role of small impoundments on a local scale? How many small impoundments exist, and what is their distribution? How have they developed over time? What ecological and water quality characteristics can be determined remotely? How best can local studies of detection and functional description be used to calibrate and upscale results to national and global scales?

Detailed comparison of multiple generally available and widely- used datasets along a transect between 32 o and 41 o N resulted in the refined estimate of small impoundment densities and distributions mapped below (Smith et al. 2003) As the center of the region of highest pond density, Eastern Kansas offers an ideal opportunity for study. Two regions were selected, and a focus area within each region.

Small impoundments serve many water- related functions directly, and have indirect influence on others. FUNCTION Stock water supply Sediment and erosion control Water/environmental quality Fish production Recreation and aesthetics Habitat and conservation WATER SUPPLY ROLE Local source Reservoir/stream ‘protection’ --- (+) Diversity (“wetland”) (-) Invasive and pest species

DatasetNumber of lakes (10 3 ) Total surface area (1000 km 2 ) Average area (m 2 ) NLCD (Small WBs only) x 10 3 National Inventory of Dams x 10 7 National Atlas x 10 7 Census Tiger x 10 6 USGS 1:24000 DLG For comparison with these generally available data sets, we sampled two E. KS quadrangles (Midland and Allen SE) using: Landsat TM (30 m res.) ASTER (15 m) Duncan-Tech multi-spectral aerial photography (< 1 m) Available aerial photographs (DOQQs, crop slides, archived county records, etc.) (< 1 m) We developed historical estimates of pond development from the 1940s… …and compared with NRCS and other recent detailed coverages. Number and area of water bodies in various data sets Mapped national density estimates were developed by applying scaling factors from the DLGs to the nationally available NLCD

Results – detection and inventory (comparison areas) Data Set# Water Bodies % of Actual Number Total Sfc. Area (sq. km.) % of Actual Area Duncan Tech 97100% % ASTER8386% % ETM+5860% % KSWD33%26.115% SWIMS11%23.613%

Results – time histories and total inventory Two test Quadrangles – Midland in SE Jefferson Co., and Allen SE in NE Lyon Co. – have similar inventories, but rather different histories. Allen SE, with generally stable population and agricultural land use, showed an earlier onset of pond building, which reached a plateau by Midland, with mixed and changing land use, started later and has reached numbers similar to Allen SE with a nearly linear increase.

Midland 1941 Midland 1954 Midland 1991 Midland 2002

False-color images of NE Kansas farm ponds taken with the MS3100 multispectral camera. Left: moderately turbid water, some vegetation at edges. Center: clear water, little vegetation. Right: pond clogged with vegetation and sediment, but with moderately clear water in places. Results – ecological and biogeochemical function Ground-truth comparisons have shown that multi-spectral images can reliably identify many aspects of water quality and pond ecology, as well as characterizing the surrounding landscape.

Filtration and reaction – biogeochemical effects of pond density (W. H. Renwick)

Relation between impoundment density and area tributary to impoundments ( W. H. Renwick ) DLG-based estimates – lower than but comparable to results of this study M91M A91 A03 Although the graphed points would have higher densities if they were derived with our techniques, the conclusion is inescapable – most of the area of E KS watersheds drains through one or (often) more ponds before reaching a perennial stream or a water body large enough to appear in most of the statewide datasets or maps.

Observations and Conclusions Millions of small artificial impoundments now dot the landscape of the conterminous U.S., at an average density of 0.3 per km 2 but reaching densities of >5 per km 2 in many regions. -These represent profound alterations to the landscape, mostly within the past 50 years. -The “norms” used for the design of most major reservoirs did not include the effects of these ponds Although relatively small in cumulative area and volume, their high surface/volume ratio and proximity to the source of runoff makes them efficient distributed reactors. -Calculations show they play a major role in sediment and carbon sequestration; effects on dissolved chemicals are significant but more difficult to estimate.

Observations and Conclusions, continued The high concentration of ponds coincident with the geographic transition from water surplus to water testifies to their water supply functions. -Considered alone, ponds have a beneficial effect on downstream water quality, but they may accompany or facilitate detrimental land uses. The combination of remote sensing and modeling with limited ground-truth calibration can inventory and classify ponds, and evaluate their landscape-scale effects on water quality and the general ecosystem -- more to follow!