SPATIAL RELATIONS OF TOPOGRAPHY, LITHOLOGY AND WATER QUALITY IN A LARGE RIVER FLOODPLAIN

Floodplains exert important controls on water and nutrient processing, yet spatial heterogeneities in floodplain characteristics result in variable effectiveness. In this study, we evaluated the spatial relations among topographic, lithologic and water quality features within the Cedar River floodplain located in southeastern Iowa. Floodplain topography and lithology were dominated by a series of sandy ridges and fine-textured swales typical of a natural meandering river floodplain complex. Groundwater sampling results from 10 monitoring wells placed in representative ridge and swale environments indicated that water quality varied systematically. Beneath sand-dominated ridges, water was aerobic and had low specific conductance, and higher concentration of NO3–N and lower concentrations of PO4–P and dissolved organic carbon (DOC). Groundwater beneath swales was anaerobic and typified by high specific conductance, and higher concentrations of NH4–N, PO4–P and DOC. We extrapolated the results from point measurements to the entire floodplain area using surface geophysics and light detection and ranging using co-kriging to map the distribution of groundwater geochemical environments at the study site. Results are seen to provide an approach to better predict shallow groundwater quality in large river floodplains and improve our ability to manage ecosystem services in these strategic locations. Copyright © 2011 John Wiley & Sons, Ltd.

[1]  Olivier Gimenez,et al.  Patterns of denitrification rates in European alluvial soils under various hydrological regimes , 2007 .

[2]  Nancy B. Grimm,et al.  Spatial Heterogeneity of Denitrification in Semi-Arid Floodplains , 2009, Ecosystems.

[3]  T. Burt,et al.  Denitrification in riparian buffer zones : the role of floodplain hydrology , 1999 .

[4]  L. Solórzano.  DETERMINATION OF AMMONIA IN NATURAL WATERS BY THE PHENOLHYPOCHLORITE METHOD 1 1 This research was fully supported by U.S. Atomic Energy Commission Contract No. ATS (11‐1) GEN 10, P.A. 20. , 1969 .

[5]  K. Schilling,et al.  Groundwater nutrient concentrations near an incised midwestern stream: effects of floodplain lithology and land management , 2008 .

[6]  Klement Tockner,et al.  Biodiversity of floodplain river ecosystems: ecotones and connectivity1 , 1999 .

[7]  Peter J. Dillon,et al.  The influence of hydrologic conditions and peat oxia on the phosphorus and nitrogen dynamics of a conifer swamp , 1993 .

[8]  D. Nielsen,et al.  Associations between the plant communities of floodplain wetlands, water regime and wetland type , 2010 .

[9]  C. Richardson,et al.  A spatially explicit investigation of phosphorus sorption and related soil properties in two riparian wetlands. , 2004, Journal of environmental quality.

[10]  K. Schilling,et al.  Water uptake and nutrient concentrations under a floodplain oak savanna during a non‐flood period, lower Cedar River, Iowa , 2009 .

[11]  Alan R. Hill,et al.  Groundwater phosphate dynamics in a river riparian zone: effects of hydrologic flowpaths, lithology and redox chemistry , 2001 .

[12]  Arthur J. Gold,et al.  Challenges to incorporating spatially and temporally explicit phenomena (hotspots and hot moments) in denitrification models , 2009 .

[13]  Kelly K. Caylor,et al.  On soil moisture–vegetation feedbacks and their possible effects on the dynamics of dryland ecosystems , 2007 .

[14]  James M. Tiedje,et al.  Denitrification in north temperate forest soils: Spatial and temporal patterns at the landscape and seasonal scales , 1989 .

[15]  G. Pinay,et al.  Seasonal dynamics of denitrification along topohydrosequences in three different riparian wetlands. , 2002, Journal of environmental quality.

[16]  A. Gallardo.  Spatial Variability of Soil Properties in a Floodplain Forest in Northwest Spain , 2003, Ecosystems.

[17]  S. E. Block,et al.  Biogeochemistry at the zone of intermittent saturation: Field-based study of the shallow alluvial aquifer, Rio Grande, New Mexico , 2007 .

[18]  A. Planty‐Tabacchi,et al.  Geomorphic control of denitrification in large river floodplain soils , 2000 .

[19]  H. Olde Venterink,et al.  Role of active floodplains for nutrient retention in the river Rhine. , 2003, Journal of environmental quality.

[20]  Olivier Bour,et al.  Hydrological flowpaths and nitrate removal rates within a riparian floodplain along a fourth‐order stream in Brittany (France) , 2003 .

[21]  R. Naiman,et al.  A Quantitative Model of Soil Organic Matter Accumulation During Floodplain Primary Succession , 2009, Ecosystems.

[22]  R. Naiman,et al.  Basic Principles and Ecological Consequences of Changing Water Regimes on Nitrogen Cycling in Fluvial Systems , 2002, Environmental management.

[23]  Connie L. Dettman,et al.  Lessons Learned about Research and Management: A Case Study from a Midwest Lowland Savanna, U.S.A. , 2008 .

[24]  Stephen R. Carpenter,et al.  Do dams and levees impact nitrogen cycling? Simulating the effects of flood alterations on floodplain denitrification , 2005 .

[25]  James R. Crum,et al.  SOIL RESOURCES, MICROBIAL ACTIVITY, AND PRIMARY PRODUCTION ACROSS AN AGRICULTURAL ECOSYSTEM , 1997 .

[26]  S. Hobbie,et al.  Spatial and temporal variation in islands of fertility in the Sonoran Desert , 2005 .

[27]  C. Hupp,et al.  CARBON, NITROGEN, AND PHOSPHORUS ACCUMULATION IN FLOODPLAINS OF ATLANTIC COASTAL PLAIN RIVERS, USA , 2005 .

[28]  N. Grimm,et al.  Nutrient dynamics at the interface between surface waters and groundwaters , 1998 .

[29]  Klement Tockner,et al.  River flood plains are model ecosystems to test general hydrogeomorphic and ecological concepts , 2010 .

[30]  Arthur J. Gold,et al.  LANDSCAPE ATTRIBUTES AS CONTROLS ON GROITHD WATER NITRATE REMOVAL CAPACITY OF RIPARIAN ZONES 1 , 2001 .

[31]  E. Tabacchi,et al.  Reciprocal interactions and adjustments between fluvial landforms and vegetation dynamics in river corridors: A review of complementary approaches , 2007 .

[32]  William H. McDowell,et al.  Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems , 2003, Ecosystems.

[33]  E. Stanley,et al.  Rapid Nitrate Loss and Denitrification in a Temperate River Floodplain , 2005 .

[34]  J. Sánchez-Pérez,et al.  Spatial and temporal variations of nutrient concentration in the groundwater of a floodplain : effect of hydrology, vegetation and substrate , 1999 .

[35]  G. J. Palacky,et al.  Use of airborne electromagnetic methods for resource mapping , 1993 .