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Existing stochastic rainfall generators (SRGs) are typically limited to relatively small domains due to spatial stationarity assumptions, hindering their usefulness for flood studies in large basins. This study proposes StormLab, an SRG that simulates precipitation events at 6‐hr and 0.03° resolution in the Mississippi River Basin (MRB). The model focuses on winter and spring storms caused by water vapor transport from the Gulf of Mexico—the key flood‐generating storm type in the basin. The model generates anisotropic spatiotemporal noise fields that replicate local precipitation structures from observed data. The noise is transformed into precipitation through parametric distributions conditioned on large‐scale atmospheric fields from a climate model, reflecting spatial and temporal nonstationarity. StormLab can produce multiple realizations that reflect the uncertainty in fine‐scale precipitation arising from a specific large‐scale atmospheric environment. Model parameters were fitted monthly from December–May, based on storms identified from 1979 to 2021 ERA5 reanalysis data and Analysis of Record for Calibration (AORC) precipitation. StormLab then generated 1,000 synthetic years of precipitation events based on 10 CESM2 ensemble simulations. Empirical return levels of simulated annual maxima agree well with AORC data and show an overall increase in 1‐ to 500‐year events in the future period (2022–2050). To our knowledge, this is the first SRG simulating nonstationary, anisotropic high‐resolution precipitation over continental‐scale river basins, demonstrating the value of conditioning such stochastic models on large‐scale atmospheric variables. StormLab provides a wide range of extreme precipitation scenarios for design floods in the MRB and can be further extended to other large river basins. Key Points: A nonstationary stochastic rainfall generator driven by water vapor transport is proposed to simulate storms in the Mississippi Basin1,000 synthetic years of precipitation events were simulated based on large‐scale atmospheric variables from a global climate modelSimulations showed an increase in 1‐ to 500‐year precipitation in the future (2022–2050) compared to the historical period (1979–2021) [ABSTRACT FROM AUTHOR]

AbstractRound goby Neogobius melanostomus – a small, benthic fish native to Eurasia – was first introduced to North America in the 1980s through ballast water of cargo ships. In 1990, the Round goby was first discovered in the Laurentian Great Lakes Basin and rapidly spread through all Great Lakes from 1993 to 1998. The Round goby is an aggressive, prolific, and efficient egg predator that subsequently displaced native fishes from their preferred habitats and resources in the Great Lakes, where they are well established and abundant. From Lake Michigan, Round goby moved south into the Chicago Area Waterway System in 1993 and slowly progressed down the Illinois Waterway to the Mississippi River from 2004 to 2019, where less is known about their abundance, establishment, and impact. The goal of this study was to gain a comprehensive understanding of the first large river invasion by Round goby in the Mississippi River Basin by leveraging Round goby capture data from 2019 to 2022 on all pools of the Illinois Waterway. We describe their current distribution, relative abundance (i.e., catch-per-unit-effort), frequency of occurrence, and establishment (i.e., presence of young-of-year and adults) status throughout the Illinois Waterway. Results show that catch-per-unit-effort, frequency of occurrence, and the proportion of sites where multiple life stages are present are considerably higher in the upstream pools relative to more downstream pools of the Illinois Waterway. Our data support that the Round goby has established self-sustaining populations in the Chicago Area Waterway System, the upper Illinois River (i.e. Dresden Island Pool downstream through Starved Rock Pool), and a portion of the lower Illinois River (i.e. Peoria Pool downstream through Alton Pool) of the Illinois Waterway. In the lower Illinois River, Round gobies appear to only be established in Peoria Pool, with captures occurring infrequently in La Grange Pool, and no Round gobies being captured in Alton Pool.

Apocorophium lacustre – a species of benthic amphipod native to American and European estuaries along the North Atlantic Ocean – has rapidly expanded outside of its native range and is now established in the Illinois, Upper Mississippi, and Ohio river systems, USA. A. lacustre is considered high risk for colonization and disruption of the Laurentian Great Lakes’ benthic communities. To further our understanding of factors influencing A. lacustre distribution and its threat to the Great Lakes, zoobenthic and habitat data were collected from colonization samplers (i.e., rock bags) deployed at 370 sites along the Illinois Waterway. A. lacustre was found in the lower six pools of the Illinois Waterway and was the most abundant amphipod collected in those pools. Our results parallel other studies in that A. lacustre was not observed upstream of Dresden Island Pool, but A. lacustre was found ~11 km farther upstream of any previous records. Generalized linear mixed effects modeling indicated that parameters pertaining to food availability, water quality, and impoundment influenced A. lacustre abundance. Model averaging identified five statistically significant variables: A. lacustre abundance was negatively associated with turbidity, fluorescent dissolved organic matter, and vegetation density and positively associated with temperature and downstream distance (i.e., closer to the next downstream dam). Our findings of what factors influence A. lacustre abundance should be of broad interest to risk assessment and invasion forecasting in other regions where A. lacustre have been or may be introduced. [ABSTRACT FROM AUTHOR]

Agricultural land managers in the Mississippi Alluvial Plain rely on the Mississippi River Valley Alluvial Aquifer for the majority of the water used for irrigation in the region. Pumping that outpaces recharge has resulted in significant cones of depression in the region, increasing pumping costs and forcing producers to use more surface water, often in the form of constructing on-farm storage reservoirs. At the same time, efforts are underway to improve groundwater models to run scenarios of conjunctive water management in the region. The improved models require accurate depiction of how the system is being managed including the use of on-farm storage reservoirs. This study extends our knowledge of on-farm storage reservoir construction from those established by a previous study that tracked reservoir construction between 1996 and 2015 backward an additional 20 years to 1976. This was accomplished by using older multi-band satellite and aerial imagery. The study area covers portions of two Critical Groundwater Regions in eastern Arkansas. Reservoir construction was classified into five-year bins starting in 1976 and ending in 2015. Details of how older imagery was processed and analyzed are provided. Previously, nearly 50% of the on-farm storage reservoirs had unknown construction dates, but this research study resolved construction dates for 85% and 72% of the reservoirs in the two study areas. Relationships between time and depth to groundwater, reservoir size, previous land use, and saturated aquifer thickness are described and contrasted in the two study areas across the 40-year study period. Use of the information provided will help guide policy and resource allocation for future reservoir construction activities and help improve conjunctive water management of the region. Specifically, the addition of this historic information will allow modelers to further refine groundwater-surface water models and should improve water resources scenarios that include reservoirs as a tool to reduce groundwater decline.

Soil erosion and sedimentation problems remain a major water quality concern for making watershed management policies in the Mississippi River Basin (MRB). It is unclear whether the observed decreasing trend of stream suspended sediment loading to the mouth of the MRB over the last eight decades truly reflects a decline in upland soil erosion in this large basin. Here, we improved a distributed regional land surface model, the Dynamic Land Ecosystem Model, to evaluate how climate and land use changes have impacted soil erosion and sediment yield over the entire MRB during the past century. Model results indicate that total sediment yield significantly increased during 1980–2018, despite no significant increase in annual precipitation and runoff. The increased soil erosion and sediment yield are mainly driven by intensified extreme precipitation (EP). Spatially, we found notable intensified EP events in the cropland‐dominated Midwest region, resulting in a substantial increase in soil erosion and sediment yield. Land use change played a critical role in determining sediment yield from the 1910s to the 1930s, thereafter, climate variability increasingly became the dominant driver of soil erosion, which peaked in the 2010s. This study highlights the increasing influences of extreme climate in affecting soil erosion and sedimentation, thus, water quality. Therefore, existing forest and cropland Best Management Practices should be revisited to confront the impacts of climate change on water quality in the MRB. Plain Language Summary: Climate and human activities have the potential to aggravate soil erosion and sediment yield in rivers, causing water quality degradation in the Mississippi River Basin (MRB). This study evaluated the impacts of climate and land use changes on sediment yield across the entire MRB by using a regional computer simulation model. The simulated results show that the increased extreme precipitation (EP) has amplified soil erosion and sediment yield in cropland‐dominated regions in the 2010s. Since the 1930s, climate variability has replaced land use change and become the dominant contributor to the changes in sediment yield. This study highlights the risks of EP on soil erosion and water quality in the MRB and emphasizes the need for appropriate management strategies to address these emerging challenges. Key Points: Increased extreme precipitation (EP) events have amplified soil erosion and sedimentation in the Mississippi River Basin since the 1990sA shift in the spatial pattern of EP events substantially intensified sediment yield in the Midwest in the 2010sThe major driver of soil erosion and sediment yield shifted from land use change to climate change during the past century [ABSTRACT FROM AUTHOR]

The rapid acceleration of anthropogenic phosphorus (P) loadings to watersheds has fuelled massive freshwater and coastal eutrophication and completely changed the global P cycle. Within watersheds, emitted P is transported downstream towards estuaries. Reservoirs can retain a significant proportion of this P. In the long term, this accumulated P can however be re-mobilized, a process lacking in current global P budgets. Here, we include P cycling in a coupled integrated assessment-hydrology-biogeochemistry framework with 0.5 by 0.5-degree spatial resolution and an annual time resolution, and apply it to the Mississippi River basin (MRB). We show that, while reservoirs have aided in the net retention of P, they serve as dissolved inorganic P (DIP) sources due to the transformation of legacy P in sediments. The increasing DIP sourcing in the MRB has been offsetting P retention in streams, especially towards the end of the twentieth century. Due to its bioavailability, DIP is the most likely form to trigger eutrophication. Although P inputs into the MRB have decreased since the 1970s, legacy effects are delaying positive outcomes of remediation measures. [ABSTRACT FROM AUTHOR]

As a work of social choreography, Niimikaage is meant to listen to the movement of the Mississippi River through the lives of people connected to it. Whether their story is directly connected to the river or not, water shapes the world around them.

Invasive Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix have infested and caused largescale ecological and economic damage to the Illinois, Mississippi, and Ohio rivers. We compiled demographic data from 42,995 fish from 23 pools in the Illinois, Mississippi, and Ohio rivers, which universities and management agencies previously collected as part of management, monitoring, and research activities. We used this data set to test whether demographic rates (length-weight relations including body condition, mortality, growth curves, and female maturity curves) varied among subpopulations across a gradient of invasion status. We found that length-weight relations and growth curves varied among subpopulations, whereas maturity curves did not. Our findings demonstrated spatial variability in demographic rates for Bighead and Silver carp across a broad geographic area in relation to invasion status and river conditions. Herein, we provide general subpopulation management options and present different hypotheses to explain the observed spatial variability in demographic rates. [ABSTRACT FROM AUTHOR]

The Mississippi River flows mostly south from its most northern reaches in Minnesota through the heartland of the United States down to Louisiana and the Gulf of Mexico, collecting and distributing commerce and culture with a multitude of tributaries and distributaries. The river itself is dynamic and changeable, flooding, avulsing, and remodeling its banks and channels continuously. Tentatively held in place with levees, dams, and floodways, this dynamic river is held somewhat in check, allowing towns and farms to reach right to the river’s edge, and providing some continuity and control for navigation of the famous river barges that carry a wealth of commodities up and down the river...

The Mississippi River flows mostly south from its most northern reaches in Minnesota through the heartland of the United States down to Louisiana and the Gulf of Mexico, collecting and distributing commerce and culture with a multitude of tributaries and distributaries. The river itself is dynamic and changeable, flooding, avulsing, and remodeling its banks and channels continuously. Tentatively held in place with levees, dams, and floodways, this dynamic river is held somewhat in check, allowing towns and farms to reach right to the river’s edge, and providing some continuity and control for navigation of the famous river barges that carry a wealth of commodities up and down the river...

The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On twin satellites have revealed mass variation over time by measuring Earth's gravity field anomalies since 2002. These variations can be interpreted as changes in water storage on and beneath the earth's surface. The water storage anomaly, also known as the Terrestrial Water Storage Anomaly (TWSA), has been utilized successfully to estimate a Flood Potential Index (FPI). The GRACE-based FPI (GRACE-FPI) is a good indicator of when a region is at risk of flooding. However, the GRACE data are limited by low spatial resolution, which has limited applicability to study areas smaller than 200,000 km². Since the change in storage derived from the traditional water budget equation has the same physical meaning as the GRACE TWSA, we hypothesize there are similarities in their derived FPIs. In this study, we propose another index, known as theWater Budget--based FPI (WB-FPI), which is derived using higher spatial resolution hydrological datasets and could produce similar but higherresolution results than the GRACE-FPI. When combined with the GRACE-FPI, the index could be valuable in providing flood prediction estimates on a catchment scale. Additionally, a combination of both indices could significantly reveal hydrological details for small basins. Both the GRACE-FPI and WB-FPI were applied to a case study of the flood potential of the U.S. Mississippi River Basin. Our study reveals good correlation between the resampled GRACE-FPI and WB-FPI using the Nash-Sutcliffe efficiency index to compare application efficacy. [ABSTRACT FROM AUTHOR]

Agricultural land managers in the Mississippi Alluvial Plain rely on the Mississippi River Valley Alluvial Aquifer for the majority of the water used for irrigation in the region. Pumping that outpaces recharge has resulted in significant cones of depression in the region, increasing pumping costs and forcing producers to use more surface water, often in the form of constructing on-farm storage reservoirs. At the same time, efforts are underway to improve groundwater models to run scenarios of conjunctive water management in the region. The improved models require accurate depiction of how the system is being managed including the use of on-farm storage reservoirs. This study extends our knowledge of on-farm storage reservoir construction from those established by a previous study that tracked reservoir construction between 1996 and 2015 backward an additional 20 years to 1976. This was accomplished by using older multi-band satellite and aerial imagery. The study area covers portions of two Critical Groundwater Regions in eastern Arkansas. Reservoir construction was classified into five-year bins starting in 1976 and ending in 2015. Details of how older imagery was processed and analyzed are provided. Previously, nearly 50% of the on-farm storage reservoirs had unknown construction dates, but this research study resolved construction dates for 85% and 72% of the reservoirs in the two study areas. Relationships between time and depth to groundwater, reservoir size, previous land use, and saturated aquifer thickness are described and contrasted in the two study areas across the 40-year study period. Use of the information provided will help guide policy and resource allocation for future reservoir construction activities and help improve conjunctive water management of the region. Specifically, the addition of this historic information will allow modelers to further refine groundwater-surface water models and should improve water resources scenarios that include reservoirs as a tool to reduce groundwater decline. • Construction dates of 85% and 72% of reservoirs in critical areas were resolved. • Reservoirs will likely remain small where water sources for filling are reliable. • More land will be taken out of production to accommodate reservoirs in future. • Increased reservoir construction linked to saturated aquifer lower thickness < 30%. [ABSTRACT FROM AUTHOR]

Stewardship, then, is the dialogue we have with stakeholders about their lived experiences with the same things we are studying, developing shared language and concepts, and incorporating that knowledge into our future research and outreach activities. Over time, we all see ourselves as Water People.

• TWS in southwest Arkansas-White-Red is reduced due to drought susceptibility. • Sometimes GPS is more sensitive to net precipitation than GRACE/GFO. • GPS network's PC1 can accurately detect hydrological signals (e.g., ∼0.4 cpy) The impact of climate change on terrestrial water storage (TWS) is critical for understanding the global hydrological process. The Global Positioning System (GPS) measurements, Gravity Recovery and Climate Experiment (GRACE), and GRACE Follow-On (GFO) data were used to measure the processes involved in the hydrological process in the Mississippi River Basin (MRB) from 2002 to 2021. The common-mode component (CMC) of the GPS network in the MRB obtained using principal component analysis (PCA) was utilized to study the hydrological loading deformation. The data from GRACE/GFO and hydrological models revealed a long-term trend of reduction in the TWS and obvious depletion of the groundwater storage (GWS) in the southwestern part of the MRB. Both GRACE/GFO and the GPS can accurately detect elastic land deformations in the MRB due to hydrological anomalies caused by El Niño/ Southern Oscillation (ENSO), while the sensitivity of GPS in Tennessee regions to net precipitation around 2016 is higher than that of GRACE/GFO. Furthermore, numerous interannual fluctuations and long-term periodic signals observed in both GPS and GRACE/GFO measurements are found to be intimately connected with hydrological processes and ENSO. The findings demonstrate that modern geodetic methods are useful in monitoring the impacts of climate change on hydrological process. [ABSTRACT FROM AUTHOR]

Based on satellite observations of Earth's time variable gravity field from the Gravity Recovery and Climate Experiment (GRACE), it is possible to derive variations in terrestrial water storage, which includes groundwater, soil moisture, and snow. Given auxiliary information on the latter two, one can estimate groundwater storage variations. GRACE may be the only hope for groundwater depletion assessments in data-poor regions of the world. In this study, soil moisture and snow were simulated by the Global Land Data Assimilation System (GLDAS) and used to isolate groundwater storage anomalies from GRACE water storage data for the Mississippi River basin and its four major sub-basins. Results were evaluated using water level records from 58 wells set in the unconfined aquifers of the basin. Uncertainty in the technique was also assessed. The GRACE-GLDAS estimates compared favorably with the well based time series for the Mississippi River basin and the two sub-basins that are larger than 900,000 km2. The technique performed poorly for the two sub-basins that have areas of approximately 500,000 km2. Continuing enhancement of the GRACE processing methods is likely to improve the skill of the technique in the future, while also increasing the temporal resolution. © Springer-Verlag 2006.

In late 2018, while researching the connections between environmental justice and Indigenous womxn’s activism[1], I was invited to story about how water might respond to environmental injustice and racism. In preparation, I thought about how the lands and peoples to which I belong struggle against “slow violence” brought on by the toxic effects of uranium contamination and nuclear pollution...

The 1993 summer rainfall over the Midwestern United States caused major flooding in the Upper Mississippi and Lower Missouri River basins. In this paper, a monthly comparative study of the analysis products from the European Centre for Medium-Range Weather Forecasts (ECMWF) with observations is conducted for the period September 1992 to August 1993. The model products include the ECMWF analysis for the Tropical Ocean and Global Atmosphere (TOGA) project and ECMWF reanalysis (ERA) project. Overall, the large-scale hydrological components (precipitation, evaporation, precipitable water, surface temperature, and relative humidity) appear partially improved from TOGA to ERA. Some internal inconsistencies exist in the assimilation of the ERA data from October 1992 to March 1993, in association with the dramatic prevalence of large-scale moisture divergence at 0000 UT. The separation of moisture flux into meridional and zonal components indicates that the correct description of the meridional moisture flow is of crucial importance for simulation of anomalously wet conditions. While the spatially averaged monthly fields in ERA and TOGA are reasonable (in particular, the models maintain very good mean flow), the fine-scale extremes are less accurate. The models do not reproduce observed mesoscale convective complexes due to limitations on resolution and the parameterization of precipitation processes. The new soil hydrology and boundary layer schemes of ERA work better in warm months but with no consistent improvement over TOGA. The terrestrial water budget in ERA is unrealistic, with accumulated model runoff being largely deviated from the observed streamflow. In addition to modeling internal water balance, the lack of the routing procedure and the low spatial resolution of surface hydrology are the other major reasons for this imbalance.

There is consensus that the Clean Water Act (CWA) has generally been effective in addressing point source pollution in the US. There is also consensus that non-point source (NPS) pollution, particularly from agriculture, remains a problem. The potential for the CWA framework to affect change is unclear, due to the limited power of the US federal government in addressing NPS, the contentiousness surrounding it, and the lack of funding to implement plans that have been developed. States are critical in improving water quality in the U.S. In the Mississippi River Basin, State-level Nutrient Reduction Strategies are the vehicle chosen by the Environmental Protection Agency to improve water quality. We develop an assessment of the twelve Mississippi River states' strategies. We consider three issues: whether there is science-based support for a choice, with a focus on NPS; if and how updates on progress are available; and whether there is alignment of funding and abatement priorities. We find that the use of best science is limited, the role of livestock in pollution and its abatement is ignored, and the development of Numeric Nutrient Criteria is stalled. Further, several states have not reported on their progress, and there has been little additional funding for pollution reduction. This analysis can inform broader discussions on decentralized approaches to address water quality. Unlabelled Image • Agriculture drives poor water quality in the Mississippi, the largest US watershed. • The federal government determined individual states should address the issue. • We assess the efficacy of the strategies implemented. • There is uneven use of the best science and livestock pollution is not considered. • The current approach is not effective in addressing water quality issues. [ABSTRACT FROM AUTHOR]

The Surface Water and Ocean Topography (SWOT) satellite mission will, for the first time, provide simultaneous, high‐resolution measurements of water surface elevation and extent. Here we explore the applicability of SWOT's unique sampling to capture discharge frequency behavior throughout the Mississippi River Basin. Our findings suggest the mission may capture key variability in river discharge series. SWOT orbit specifications, US Geological Survey (USGS) discharge measurements, and potential uncertainty estimates are used to generate SWOT‐like river discharges. Frequency distributions and specific quantiles derived from synthetic SWOT discharge series are compared to those derived from daily USGS discharge series. Based on the Kolmogorov‐Smirnov test, SWOT temporal sampling has essentially no impact on derived frequency distributions. When including potential uncertainty, 78% of derived distributions are statistically identical. The combined effects of temporal sampling and discharge uncertainty mitigates the negative bias used for SWOT discharge uncertainty at larger discharge quantiles (i.e., ≥75% quantiles). Plain Language Summary: The Surface Water and Ocean Topography (SWOT) satellite will, for the first time, simultaneously measure elevations and extents of the Earth's surface waters at high resolution. The satellite will measure almost everywhere on Earth as many as seven times every 21 days, with more observations at higher latitudes. In this study, we explored how nonuniform measurements in time, varying by location, impact the ability of SWOT to capture river discharge frequency behavior. Based on the comparison between discharge frequency distributions derived from daily USGS gauge measurements and synthetic SWOT observations, SWOT's unique temporal sampling does not impact observed discharge behavior. When considering both temporal sampling and uncertainty, 78% of the study locations still match the truth discharge frequency distributions. In general, SWOT temporal sampling has minimal impact on derived discharge quantiles, but the combination of both temporal sampling and uncertainty leads to underestimated discharge quantiles. The magnitude of the underestimated discharges for larger quantiles (i.e., ≥75%) is less than the negative bias used for SWOT discharge uncertainty, implying a mitigation of negative bias in discharge at larger discharge quantiles. Key Points: SWOT temporal sampling has minimal impact on derived river discharge frequency distributions throughout the Mississippi River BasinSWOT‐derived discharge distributions are statistically the same as those derived from daily in‐situ measurements in 78% of casesQuantiles derived from synthetic SWOT discharges series have RRMSE of less than 22% [ABSTRACT FROM AUTHOR]

Long chain plant waxes (n-alkanes, n-alkanoic acids, and n-alcohols) and their carbon isotopic compositions (δ13C) in geologic archives are valuable tools for paleovegetation reconstruction. However, the sensitivity of different plant wax constituents to vegetation shift is not well understood. This study explores controls on the variation in δ13C values of long-chain n-alkanes (C27 to C33) and n-alkanoic acids (C26-C30) in the Gulf of Mexico core sediments (ODP 625B) near the Mississippi River delta. n-Alkanoic acids' δ13C values were higher than those of n-alkanes by 1-2‰ on average and such a pattern is the opposite from their isotope fractionation observed in living plants: 1-2‰ smaller in n-alkanes than nalkanoic acids. We attribute this offset to contributions from aquatic plants or microbes that produce high concentrations of 13C-enriched long-chain n-alkanoic acids. The sensitivity of n-alkanes and n-alkanoic acids to vegetation and climate varied among chain lengths. The n-C33 alkanes were most sensitive to C4 grassland expansion among n-alkane homologues, while no specific trend was observed in n-alkanoic acids. This is due to the similarity in n-alkanoic acid concentrations between C3 and C4 plants by homologues and low terrestrial plant-derived n-alkanoic acid contributions to the sediments. The results of this study suggest that long chain n-alkanoic acids' δ13C values in sediments may be influenced by contributions from different sources such as aquatic plants or microbial inputs and therefore interpretations regarding this matter should be cautiously formulated. We suggest that there is a need for further studies on characterizing long-chain n-alkanoic acids (C26-C34) in aquatic plants and microbes from various climates and environments in order to investigate their production and integration into sedimentary archives. [ABSTRACT FROM AUTHOR]

Abstract A central challenge in the Mississippi River Basin is how to continue to support profitable agricultural production, provide water supply, flood control, transportation, and other benefits, while reducing the current burden of environmental degradation. Several practices have been shown to reduce nutrient runoff and water pollution, and improve soil fertility, while often yielding profits for farmers. Yet many of these beneficial practices remain underutilized. Participants at an expert workshop identified five candidate financial mechanisms that could increase adoption of these beneficial farming practices in four focal Midwest states in the next five years: crop insurance premium subsidies, transformation of the private service provider business model, expansion and targeting of 2019 U.S. Farm Bill funding, development of new state funds, and direction of post-disaster federal funds towards habitat restoration, particularly in floodplains. This study provides rough approximations of the change in nutrient runoff and greenhouse gas (GHG) emissions, the annualized costs, and the nutrient and GHG reductions per dollar likely to result from deployment of each financial mechanism. Based upon these approximations, the adoption of these programs could reduce annual nitrate flows at the outlet of the Ohio and Upper Mississippi River Basins by 25%, surpassing the intermediate 2025 target (20% reduction) and achieving more than half of the long-term target (45% reduction) set by the Mississippi River/Gulf of Mexico Hypoxia Task Force. These approximations also illustrate that these five mechanisms could provide the same GHG reductions (∼43 Tg CO 2 e yr−1) as taking 12 coal-fired energy plants offline. The total cost of these five financial mechanisms is estimated at ∼$2.6 billion, or 64 g of nitrates and ∼17 kg of CO 2 e per dollar spent. These proposed solutions all face political, financial, cultural or institutional challenges, but with industry support, creative political action, and continued communication of both private and public benefits, they can create meaningful nutrient reductions and rebuild soils by 2022. Highlights • Financial mechanisms for incentivizing land use practices that reduce impacts in Mississippi River Basin are explored. • Five mechanisms with potential to create swift and widespread change are analyzed. • These five mechanisms can achieve the intermediate 2025 target for reducing the Gulf of Mexico dead zone. • The GHG reductions achieved by these mechanisms would be equivalent to taking 13 coal fired power plants offline. • A sliding scale for crop insurance has the largest impact and is also the most cost effective. [ABSTRACT FROM AUTHOR]

A watershed model was developed using the Soil and Water Assessment Tool (SWAT) that simulates nitrogen, phosphorus, and sediment loadings in the Lower Mississippi River Basin (LMRB). The LMRB SWAT model was calibrated and validated using 21 years of observed flow, sediment, and water-quality data. The baseline model results indicate that agricultural lands within the Lower Mississippi River Basin (LMRB) are the dominant sources of nitrogen and phosphorus discharging into the Gulf of Mexico. The model was further used to evaluate the impact of biomass production, in the presence of riparian buffers in the LMRB, on suspended-sediment and nutrient loading discharge from the Mississippi River into the Gulf of Mexico. The interplay among land use, riparian buffers, crop type, land slope, water quality, and hydrology were anlyzed at various scales. Implementing a riparian buffer in the dominant agricultural region within the LMRB could reduce suspended sediment, nitrogen, and phosphorus loadings at the regional scale by up to 65%, 38%, and 39%, respectively. Implementation of this land management practice can reduce the suspended-sediment content and improve the water quality of the discharge from the LMRB into the Gulf of Mexico and support the potential production of bioenergy and bio-products within the Mississippi River Basin. [ABSTRACT FROM AUTHOR]

Improved understanding of water quality at the edge-of-field (EOF) from production-size fields is needed to better inform agriculture and resource managers regarding sustainable farming practices and environmental stewardship. We measured runoff water quality at EOF of paired commercial fields in Mississippi and Craighead counties (total of four fields) in the Mississippi Delta region of eastern Arkansas, an understudied agricultural region. The paired fields had similar size, soil properties, and crop (cotton [Gossypium hirsutum L.] or corn [Zea mays L.]). Runoff water quality (nitrate [NO3], nitrite [NO2], total nitrogen [TN], phosphate [PO4], total phosphorus [TP], and suspended sediment concentration) and quantity (discharge) were measured using sensors and automated water samplers installed in surface drainage pipes at the EOF and laboratory analysis. We monitored both precipitation and irrigation events for three years, with the first two years in cover crop and the third year in baseline study. We used the data to evaluate (1) the effectiveness of cover crops in reducing nutrients and sediment losses, (2) differences in growing season and nongrowing season losses, and (3) changes in runoff water quality from irrigation tailwater compared to rainfall event runoff during the growing seasons. We also compared variations in pollutant loadings in the paired fields under identical crop and management practices for baseline monitoring. Cover crops effectively reduced concentrations of NO3-N and PO4-P from one field pair at the Caraway location. Generally, concentrations of pollutants were lower in the growing period (May through October) than in the nongrowing period (November through April), suggesting the need for practices such as cover crops to reduce winter loads. Runoff water quality after irrigation was not different from that after rainfall. These findings support the need for baseline studies before actual evaluation of conservation practices, and practices including cover crops at the field in winter. [ABSTRACT FROM AUTHOR]

In physical space, where is the Mississippi River? This may seem like a relatively straightforward question, but from the perspective of a historian, I think a different question—What is the Mississippi River?—needs to be answered first.

What happens when you leave the confines of the classroom, step away from the whiteboards, data projectors, and PowerPoints, and move into the richness of the world itself? In August 2015, a group 17 students, staff, and faculty from Augsburg College loaded four 24-foot voyageur canoes with their gear and started paddling down the Mississippi River as part of the first River Semester.

...A movement has grown at Standing Rock, inspiring the largest gathering of American Indian tribes in over a century. In attempting to understand this historical contestation over water resources and tribal sovereignty, the question of treaty rights has been on the lips of Standing Rock water protectors, as well as scholars, community leaders, politicians, and commentators.

Nitrogen (N) export from the Mississippi River Basin contributes to seasonal hypoxia in the Gulf of Mexico (GOM). We explored monthly dissolved inorganic N (DIN) export to the GOM for a historical year (2002) and two future scenarios (year 2022) by linking macroeonomic energy, agriculture market, air quality, and agriculture land management models to a DIN export model. Future scenarios considered policies aimed at encouraging bioenergy crop production and reducing atmospheric N-emissions, as well as the effect of population growth and the states' infrastructure plans on sewage fluxes. Model-derived DIN export decreased by about 9% (from 279 to 254 kg N km year) between 2002 and 2022 due to a 28% increase in area planted with corn, 24% improvement in crop N-recovery efficiency (NRE, to 0.52), 22% reduction in atmospheric N deposition, and 23% increase in sewage inputs. Changes in atmospheric and sewage inputs had a relatively small effect on DIN export and the effect of bioenergy crop production depended on nutrient management practices. Without improved NRE, increased production of corn would have increased DIN export by about 14% (to 289 kg N km year) between 2002 and 2022. Model results suggest that meeting future crop demand while reducing the areal extent of hypoxia could require aggressive actions, such improving basin-level crop NRE to 0.62 or upgrading N-removal capabilities in waste water treatment plants beyond current plans. Tile-drained cropland could contribute up to half of DIN export; thus, practices that reduce N losses from tile drains could also have substantial benefit. [ABSTRACT FROM AUTHOR]

As a key component of the National Flood Interoperability Experiment ( NFIE), this article presents the continental scale river flow modeling of the Mississippi River Basin ( MRB), using high-resolution river data from NHD Plus. The Routing Application for Parallel computatIon of Discharge ( RAPID) was applied to the MRB with more than 1.2 million river reaches for a 10-year study (2005-2014). Runoff data from the Variable Infiltration Capacity ( VIC) model was used as input to RAPID. This article investigates the effect of topography on RAPID performance, the differences between the VIC- RAPID streamflow simulations in the HUC-2 regions of the MRB, and the impact of major dams on the streamflow simulations. The model performance improved when initial parameter values, especially the Muskingum K parameter, were estimated by taking topography into account. The statistical summary indicates the RAPID model performs better in the Ohio and Tennessee Regions and the Upper and Lower Mississippi River Regions in comparison to the western part of the MRB, due to the better performance of the VIC model. The model accuracy also increases when lakes and reservoirs are considered in the modeling framework. In general, results show the VIC- RAPID streamflow simulation is satisfactory at the continental scale of the MRB. [ABSTRACT FROM AUTHOR]

Recent studies have found insignificant or decreasing trends in time-series dissolved organic carbon (DOC) datasets, questioning the assumption that long-term DOC concentrations in surface waters are increasing in response to anthropogenic forcing, including climate change, land use, and atmospheric acid deposition. We used the weighted regressions on time, discharge, and season (WRTDS) model to estimate annual flow-normalized concentrations and fluxes to determine if changes in DOC quantity and quality signal anthropogenic forcing at 10 locations in the Mississippi River Basin. Despite increases in agriculture and urban development throughout the basin, net increases in DOC concentration and flux were significant at only 3 of 10 sites from 1997 to 2013 and ranged between −3.5% to +18% and −0.1 to 19%, respectively. Positive shifts in DOC quality, characterized by increasing specific ultraviolet absorbance at 254 nm, ranged between +8% and +45%, but only occurred at one of the sites with significant DOC quantity increases. Basinwide reductions in atmospheric sulfate deposition did not result in large increases in DOC either, likely because of the high buffering capacity of the soil. Hydroclimatic factors including annual discharge, precipitation, and temperature did not significantly change during the 17-year timespan of this study, which contrasts with results from previous studies showing significant increases in precipitation and discharge over a century time scale. Our study also contrasts with those from smaller catchments, which have shown stronger DOC responses to climate, land use, and acidic deposition. This temporal and spatial analysis indicated that there was a potential change in DOC sources in the Mississippi River Basin between 1997 and 2013. However, the overall magnitude of DOC trends was not large, and the pattern in quantity and quality increases for the 10 study sites was not consistent throughout the basin. [ABSTRACT FROM AUTHOR]