Riparian Zone Nitrogen Management through the Development of the Riparian Ecosystem Management Model (REMM) in a Formerly Glaciated Watershed of the US Northeast

The Riparian Ecosystem Management Model (REMM) was developed, calibrated and validated for both hydrologic and water quality data for eight riparian buffers located in a formerly glaciated watershed (upper Pawcatuck River Watershed, Rhode Island) of the US Northeast. The Annualized AGricultural Non-Point Source model (AnnAGNPS) was used to predict the runoff and sediment loading to the riparian buffer. Overall, results showed REMM simulated water table depths (WTDs) and groundwater NO3-N concentrations at the stream edge (Zone 1) in good agreement with measured values. The model evaluation statistics showed that, hydrologically REMM performed better for site 1, site 4, and site 8 among the eight buffers, whereas REMM simulated better groundwater NO3-N concentrations in the case of site 1, site 5, and site 7 when compared to the other five sites. The interquartile range of mean absolute error for WTDs was 3.5 cm for both the calibration and validation periods. In the case of NO3-N concentrations prediction, the interquartile range of the root mean square error was 0.25 mg/L and 0.69 mg/L for the calibration and validation periods, respectively, whereas the interquartile range of d for NO3-N concentrations was 0.20 and 0.48 for the calibration and validation period, respectively. Moreover, REMM estimation of % N-removal from Zone 3 to Zone 1 was 19.7%, and 19.8% of N against actual measured 19.1%, and 26.6% of N at site 7 and site 8, respectively. The sensitivity analyses showed that changes in the volumetric water content between field capacity and saturation (soil porosity) were driving water table and denitrification

Evaluation of AnnAGNPS Model for Runoff Simulation on Watersheds from Glaciated Landscape of USA Midwest and Northeast

Runoff modeling of glaciated watersheds is required to predict runoff for water supply, aquatic ecosystem management and flood prediction, and to deal with questions concerning the impact of climate and land use change on the hydrological system and watershed export of contaminants of glaciated watersheds. A widely used pollutant loading model, Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) was applied to simulate runoff from three watersheds in glaciated geomorphic settings. The objective of this study was to evaluate the suitability of the AnnAGNPS model in glaciated landscapes for the prediction of runoff volume. The study area included Sugar Creek watershed, Indiana; Fall Creek watershed, New York; and Pawcatuck River watershed, Rhode Island, USA. The AnnAGNPS model was developed, calibrated and validated for runoff estimation for these watersheds. The daily and monthly calibration and validation statistics (NSE \u3e 0.50 and RSR \u3c 0.70, and PBIAS ± 25%) of the developed model were satisfactory for runoff simulation for all the studied watersheds. Once AnnAGNPS successfully simulated runoff, a parameter sensitivity analysis was carried out for runoff simulation in all three watersheds. The output from our hydrological models applied to glaciated areas will provide the capacity to couple edge-of-field hydrologic modeling with the examination of riparian or riverine functions and behaviors

The impact of flooding on aquatic ecosystem services

Flooding is a major disturbance that impacts aquatic ecosystems and the ecosystem services that they provide. Predicted increases in global flood risk due to land use change and water cycle intensification will likely only increase the frequency and severity of these impacts. Extreme flooding events can cause loss of life and significant destruction to property and infrastructure, effects that are easily recognized and frequently reported in the media. However, flooding also has many other effects on people through freshwater aquatic ecosystem services, which often go unrecognized because they are less evident and can be difficult to evaluate. Here, we identify the effects that small magnitude frequently occurring floods (\u3c 10-year recurrence interval) and extreme floods (\u3e 100-year recurrence interval) have on ten aquatic ecosystem services through a systematic literature review. We focused on ecosystem services considered by the Millennium Ecosystem Assessment including: (1) supporting services (primary production, soil formation), (2) regulating services (water regulation, water quality, disease regulation, climate regulation), (3) provisioning services (drinking water, food supply), and (4) cultural services (aesthetic value, recreation and tourism). The literature search resulted in 117 studies and each of the ten ecosystem services was represented by an average of 12 ± 4 studies. Extreme floods resulted in losses in almost every ecosystem service considered in this study. However, small floods had neutral or positive effects on half of the ecosystem services we considered. For example, small floods led to increases in primary production, water regulation, and recreation and tourism. Decision-making that preserves small floods while reducing the impacts of extreme floods can increase ecosystem service provision and minimize losses

TESTING A SIMPLE FIELD METHOD FOR ASSESSING NITRATE REMOVAL IN RIPARIAN ZONES

Being able to identify riparian sites that function better for nitrate removal from groundwater is critical to using efficiently the riparian zones for water quality management. For this purpose, managers need a method that is quick, inexpensive, and accurate enough to enable effective management decisions. This study assesses the precision and accuracy of a simple method using three ground water wells and one measurement date for determining nitrate removal characteristics of riparian buffer zones. The method is a scaled-down version of a complex field research method that consists of a large network of wells and piezometers monitored monthly for over two years. Results using the simplified method were compared to those from the reference research method on a date-by-date basis on eight sites covering a wide range of hydrogeomorphic settings. The accuracy of the three-well, 1 day measurement method was relatively good for assessing nitrate concentration depletion across riparian zones, but poor for assessing the distance necessary to achieve a 90% nitrate removal and for estimating water and nitrate fluxes compared to the reference method. The simplified three-well method provides relatively better estimates of water and nitrate fluxes on sites where ground-water flow is parallel to the water table through homogeneous aquifer material, but such conditions may not be geographically widespread. Despite limited overall accuracy, some parameters that are estimated using the simplified method may be useful to water resource managers. Nitrate depletion information may be used to assess the adequacy of existing buffers to achieve nitrate concentration goals for runoff. Estimates of field nitrate runoff and buffer removal fluxes may be adequate for prioritizing management toward sites where riparian buffers are likely to have greater impact on stream water quality

RZ TRADEOFF software

RZ-TRADEOFF Water and Air Quality Model is a riparian zone model aiming to predict key riparian functions (NO3- and phosphate [PO43-] concentration and removal in subsurface flow, total phosphorus [TP] removal in overland flow, nitrous oxide [N2O], methane [CH4], and carbon dioxide [CO2] emissions, water table) based on landscape hydrogeomorphic characteristics, weather, and land cover/land use. USDA-NIFA Award # 2015-67019-23586

Impact of Urbanization on Large Wood Sizes and Associated Recruitment Zones

Although the presence of large wood (LW) has long been recognized to enhance watershed function, land use impact on LW remains poorly understood. Using a series of six watersheds, we investigate the relationships between LW recruitment zones, LW size, and LW jam occurrence and land use. Although the results in general show urban land use to severely limit LW, they also stress that agricultural land use may be positively correlated to LW. Occurrence of potentially productive LW recruitment zones is nevertheless best correlated to total forest land cover and forested riparian area. However, the lack of mature forest due to previous widespread deforestation linked to historical agricultural land use is likely a limiting legacy effect. Since the pattern of land use seen in the study area is typical of much of the developed world, our results suggest the limiting of LW may be a major way in which watersheds are impacted in many regions. Accordingly, reintroduction of LW represents a significant opportunity to restore watersheds on a broad scale. Specifically, we propose a mix of passive conservation and active restoration of LW sources and that the targeting of these tactics be planned using the spatial analysis methods of this study

Isoproturon movement and dissipation in undisturbed soil cores from a grassed buffer strip

Grassed buffer strips can efficiently reduce pesticide runoff, but questions remain concerning the behavior of trapped pesticides. Incubation and leaching experiments were carried out under laboratory controlled conditions to study the dissipation and mobility of the herbicide isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] in undisturbed soil columns from a grassed strip (GS) and a cultivated plot (CP). After surface application with $^{14}$C-labeled herbicide, soil columns were incubated for 44 d, then eluted for 15 d with water. Non-incubated columns were similarly eluted immediately after herbicide application. Isoproturon recovery in leachates was less from incubated GS soil columns (4% of applied herbicide) compared with unincubated columns (30% ). Herbicide leaching was greater in CP soil columns than in GS soil columns. Isoproturon degradation was enhanced in the GS soil, as was the formation of non-extractable (bound) residues. After incubation and leaching, 90% of initially added $^{14}$C remained in the GS columns and in particular within the surface 2 cm of soil (60% ).Mobilité et dissipation de l'isoproturon dans des colonnes de sol de bandes enherbés. Les bandes enherbées réduisent efficacement les pertes de pesticides par ruissellement mais le devenir des produits retenus est mal connu. La mobilité et la dissipation de l'isoproturon ont été étudiées en conditions controlées de laboratoire dans des colonnes de sols non perturbés provenant d'une bande enherbée (GS) et d'un sol cultivé (CP). Après application de $^{14}$C-isoproturon, les colonnes ont été incubées pendant 44 j, puis ont subi une percolation de 15 j. Des colonnes non-incubées ont été éluées de façon identique après application d'herbicide. La mise en incubation des colonnes réduit fortement la lixiviation de l'isoproturon. Pour le sol enherbé, le taux de récupération dans les solutions percolées passe de 30 % de l'herbicide appliqué sans incubation à 4 % après incubation. Par rapport au sol cultivé, la lixiviation de l'isoproturon est moindre dans le sol enherbé alors que sa dégradation et la formation de résidus liés sont fortement augmentées. Après incubation et percolation, 90 % de la radioactivité appliquée reste dans les colonnes, majoritairement localisée dans les premiers 2 cm du sol enherbé (60 % )

Unrestricted cattle access to streams and water quality in till landscape of the Midwest

Unrestricted cattle access to streams in traditionally pastoral regions has been linked to increased concentrations of bacteria, suspended sediments and associated contaminants in streams. However, there is a dearth of data available regarding the impact of cattle access to streams in poorly drained landscapes of the Midwest. In this study, we investigate changes in water quality on a 1005 m long stream section impacted by cattle grazing on the upper 130 m. We monitor discharge, water quality [nitrate, ammonium, total Kjeldahl nitrogen (TKN), total phosphorus (TP), total suspended sediments (TSS), turbidity, Escherichia coli] and chloride, atrazine, silica and major cation concentrations over a 12-month period. Cattle access to the stream does not significantly affect nitrate concentration but leads to large increases in TKN (fourfold increase), TP (fivefold increase), ammonium (fourfold increase), TSS (11-fold increase), turbidity (13-fold increase) and E. coli (36-fold increase) in the summer/fall period. In particular, E. coli concentration in the stream in the summer/fall period exceeds 235 colony forming unit (CFU)/100 ml 64% of the time upstream from the section impacted by cattle, but exceeds this same threshold 89% of the time immediately downstream. Despite the negative impact of cattle access to the stream on water quality, data indicate that dilution, in-stream processes, and natural stream geometry downstream from the impacted section help mitigate this pollution. We expect that this study will be an incentive for policy makers to promote stream rehabilitation and develop more stringent guidelines limiting cattle access to streams in many Midwestern states and other regions with poorly drained soils where the impact of cattle access to streams on water quality is often ignored.

Storm Dissolved Organic Carbon Dynamics in an Artificially Drained Watershed of the US Midwest

This study investigates changes in the nature, concentrations, and fluxes of dissolved organic carbon (DOC) in tile drains (aka subsurface drains), overland flow, and stream flow for 6 spring storms in an artificially drained agricultural watershed. For moderate size storms, DOC concentrations are primarily affected by variations in antecedent moisture conditions. Generally, DOC concentrations and aromaticity increase with flow, especially for storms associated with high antecedent moisture conditions. A shift in the source of DOC to the stream and tile drains from low aromaticity DOC at baseflow, to more aromatic DOC during storms was observed. Data indicates that increases in the frequency and intensity of large precipitation events as well as wetter conditions in spring would likely lead not only to an increase in DOC fluxes (simply because of higher discharge) but also to an increase in the amount of DOC exported for every unit of flow

A new approach to generalizing riparian water and air quality function across regions

There is growing interest in generalizing the impact of hydrogeomorphology and weather variables on riparian functions. Here, we used RZ-TRADEOFF to estimate nitrogen, phosphorus, water table (WT) depth, and greenhouse gas (GHG: N 2 O, CO 2 , CH 4 ) functions for 80 riparian zones typical of the North American Midwest, Northeast (including Southern Ontario, Canada), and Mid-Atlantic. Sensitivity to weather perturbations was calculated for temperature and precipitation-dependent functions (CO 2 , phosphate concentration, and water table), and multivariate statistical analysis on model outputs was conducted to determine trade-offs between riparian functions. Mean model estimates were 93.10 cm for WT depth, 8.45 mg N L −1 for field edge nitrate concentration, 51.57% for nitrate removal, 0.45 mg PO 43− L −1 for field edge phosphate concentration, 1.5% for subsurface phosphate removal, 91.24% for total overland phosphorus removal, 0.51 mg N m −2 day −1 for N 2 O flux, 5.5 g C m −2 day −1 for CO 2 fluxes, and − 0.41 mg C m −2 day −1 and 621.51 mg C m −2 day −1 for CH 4 fluxes in non-peat sites and peat sites, respectively. Sites in colder climates were most sensitive to weather perturbations for CO 2 , sites with deep water tables estimates had the highest sensitivity for WT, and sites in warm climates and/or with deep confining layers had the lowest sensitivity for phosphate concentration. Slope, confining layer depth, and temperature were the primary characteristics influencing similarities and trade-offs between sites. This research contributes to understanding how to optimize riparian restoration and protection in watersheds based on both water (nitrogen, phosphorus) and air quality (GHG) goals