Channelizing streams for agricultural drainage impairs their nutrient removal capacity

In agricultural basins, fluvial ecosystems can work as filters when retaining the nutrient excess from agricultural activities, mitigating the impacts downstream. In frequently flooded areas, like the Pampas Region of Argentina, natural streams are being channelized to reduce flood frequency and intensity, thus increasing land suitability for crop production, but the impact of these interventions on nutrient removal capacity by streams is unknown. To evaluate the effects of channelizing streams on the assimilation rate of nitrate, ammonia, and phosphorus, nutrient addition experiments were performed in streams of the southern Pampas under three different conditions: (i) channelized reaches without Schoenoplectus californicus (C.A. Mey.) Palla (reeds), (ii) unchannelized reaches without reeds, and (iii) unchannelized reaches with reeds. Assimilation rates were estimated by applying the one-dimensional transport with inflow and storage (OTIS) model, which considers the solute transport with lateral flow and storage. Nitrate and ammonia uptake rates were higher in unchannelized than in channelized stream reaches, and a higher nitrate assimilation rate was found in the presence of reeds, indicating an important role of this macrophyte in the nitrate uptake. In the case of phosphorous, uptake rates were higher in unchannelized reaches with reeds than in the channelized reaches. These results suggest that channelizing first-order streams in agricultural landscapes of the Argentine Pampas may significantly reduce the ability of streams to mitigate nutrients loss to continental and marine water sinks.Fil: Booman Zugarramurdi, Gisel Carolina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Laterra, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Indicators of nutrient removal efficiency for riverine wetlands in agricultural landscapes of Argentine Pampas

Main objectives of this study were (a) to assess wetlands contribution to regulation of surface water quality of riverine wetlands in agricultural landscapes through their nutrient removal efficiency (RE), (b) to understand how RE of wetlands is related to hydrological, morphological, chemical and biological attributes, and (c) to identify RE indicators suitable for remote RE assessment. Macrophytes composition, hydrological, chemical, and morphological properties were estimated for 14 riverine wetlands of the Argentinean Pampas, and related to empirically estimated removal-exportation levels of phosphorus (dissolved and total) and nitrogen (inorganic and total). Nutrient inputs and outputs were assessed in four opportunities, two under baseline and two after storm events. A discriminant function based on remotely assessed wetland attributes was able to discriminate three wetland groups according to their contrasting mean RE for total phosphorus and total nitrogen. Descriptors of wetland size (area, length, perimeter) and vegetation (cover of the tall emergent macrophytes) showed the main weights and hence the main value as indicators for conservation and/or management of wetlands according to their nutrient removal capacities.Fil: Laterra, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Booman Zugarramurdi, Gisel Carolina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Picone, Liliana Inés. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Videla, Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Orue, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Areal changes of lentic water bodies within an agricultural basin of the Argentinean Pampas. Disentangling land management from climatic causes

Wetland loss is a frequent concern for the environmental management of rural landscapes, but poor disentanglement between climatic and land management causes frequently constrains both proper diagnoses and planning. The aim of this study is to address areal changes induced by non-climatic factors on lentic water bodies (LWB) within an agricultural basin of the Argentinean Pampas, and the human activities that might be involved. The LWB of the Mar Chiquita basin (Buenos Aires province, Argentina) were mapped using Landsat images from 1998-2008 and then corrected for precipitation variability by considering the regional hydrological status on each date. LWB areal changes were statistically and spatially analyzed in relation to land use changes, channelization of streams, and drainage of small SWB in the catchment areas. We found that 12 % of the total LWB in the basin had changed (P < 0.05) due to non-climatic causes. During the evaluated decade, 30 % of the LWB that changed size had decreased while 70 % showed steady increases in area. The number of alteredLWB within watersheds lineally increased or decreased according to the proportion of grasslands replaced by sown pastures, or the proportion of sown pastures replaced by crop fields, respectively. Drainage and channelization do not appear to be related to the alteration of LWB; however some of these hydrologic modifications may predate 1998, and thus earlier effects cannot be discarded. This study shows that largescale changes in land cover (e.g., grasslands reduction) can cause a noticeable loss of hydrologic regulation at the catchment scale within a decade. © Springer Science+Business Media, LLC 2012.Fil: Booman Zugarramurdi, Gisel Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: Calandroni, Mirta. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Laterra, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Cabria, Fabián Néstor. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Iribarne, Oscar Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: Vázquez, Pablo. Instituto Nacional de Tecnología Agropecuaria; Argentin

Identification of wetland areas in the context of agricultural development using Remote Sensing and GIS

This study aims to determine the wetland potential on a pixel basis on the floodplain of the Leon River: hydrology, hydrophytic vegetation and hydromorphic soils were taken into account. Field measurements and spatially explicit models were used to model surface hydrology and piezometric levels. Satellite data were used to derive inundated areas and vegetation. Existing maps from the national geographic institute (IGAC) were used to define the spatial distribution of hydromorphic soils. Special attention was paid to agricultural infrastructure, levees and diversion channels used to modify surface hydrology in order to promote plantations and cattle grazing. A total of 536 km2 meet one or more wetland conditions according to biophysical variables, but only 393 km2 were selected, using logical rules, as wetland pixels. The combination of biophysical variables to define wetland potential is discussed in terms of the spatial distribution and the implications for environmental resource management.El presente estudio tiene como fin determinar el potencial de humedales a nivel de pixel en la llanura de inundación del Río León, se consideraron aspectos de hidrología, vegetación hidrofítica y suelos hidromórficos. Se utilizaron mediciones en campo y modelos distribuidos espacialmente para modelar la hidrología superficial y los niveles piezométricos. También se utilizaron imágenes de satélite para determinar áreas inundadas y vegetación. Los mapas existentes del instituto geográfico Agustín Codazzi fueron utilizados para definir la distribución espacial de los suelos hidromórficos. Se prestó atención especial a la infraestructura agrícola, donde los diques artificiales y trasvases han sido utilizados para modificar la hidrología superficial con el fin de promover el establecimiento de plantaciones y pastoreo. Un total de 536 km2 cumplieron una o más condiciones de humedal según las variables biofísicas, pero solo 393 km2 fueron seleccionados mediante reglas lógicas como pixeles de humedal. La combinación de variables biofísicas para la definición del potencial de humedal es discutida en términos de la distribución espacial y las implicaciones para el manejo de los recursos naturales

Identification of wetland areas in the context of agricultural development using Remote Sensing and GIS

This study aims to determine the wetland potential on a pixel basis on the floodplain of the Leon River: hydrology, hydrophytic vegetation and hydromorphic soils were taken into account. Field measurements and spatially explicit models were used to model surface hydrology and piezometric levels. Satellite data were used to derive inundated areas and vegetation. Existing maps from the national geographic institute (IGAC) were used todefine the spatial distribution of hydromorphic soils. Special attention was paid to agricultural infrastructure, levees and diversion channels used to modify surface hydrology in order to promote plantations and cattle grazing. A total of 536 km2 meet one or more wetland conditions according to biophysical variables, but only 393 km2 were selected, using logical rules, as wetland pixels. The combination of biophysical variables to define wetland potential is discussed in terms of the spatial distributionand the implications for environmental resource management.El presente estudio tiene como fin determinar el potencial de humedales a nivel de pixel en la llanura de inundación del Río León, se consideraron aspectos de hidrología, vegetación hidrofítica y suelos hidromórficos. Se utilizaron mediciones en campo y modelos distribuidos espacialmente para modelar la hidrología superficial y los niveles piezométricos. También se utilizaron imágenes de satélite para determinar áreas inundadas y vegetación. Los mapas existentes del instituto geográfico Agustín Codazzi fueron utilizados para definir la distribución espacial de los suelos hidromórficos. Se prestó atención especial a la infraestructura agrícola, donde los diques artificiales y trasvases han sido utilizados para modificar la hidrología superficial con el fin de promover el establecimiento de plantaciones y pastoreo. Un total de 536 km2 cumplieron una o más condiciones de humedal según las variables biofísicas, pero solo 393 km2 fueron seleccionados mediante reglas lógicas como pixeles de humedal. La combinación de variables biofísicas para la definición del potencial de humedal es discutida en términos de la distribución espacial y las implicaciones para el manejo de los recursos naturales