SEARCH · USGS Science

Results for “Agricultural Water Management”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources

USGS2021

Ungaged inflow and loss patterns in urban and agricultural sub‐reaches of the Logan River Observatory

Streams in semi‐arid urban and agricultural environments are often heavily diverted for anthropogenic purposes. However, they simultaneously receive substantial inflows from a variety of ungaged sources including stormwater returns, tile drainage, and irrigation runoff that help sustain flow during dry periods. Due to the inability to identify sources or directly gage many of these inflows, there is a clear need for methods to understand source origination while quantifying potential gains and losses over highly impacted reaches. In the context of the Logan River Observatory, historical gage data illustrate the importance of ungaged and unidentified inflows on maintaining or enhancing flows in both urban and agricultural reaches containing large diversions. To understand the inflows in this portion of the Logan River, we first analysed water samples for ions collected from a subset of representative inflow sources and applied clustering analyses to establish inflow source classifications and associated ion concentration ranges. These representative concentration ranges, combined with mainstem flow and river ion samples taken at sub‐reach scales, allow for the application of flow and mass balances to quantify inflow rates from different sources as well as any losses. These calculations demonstrate significant gains and losses occurring in many sub‐reaches during three sampling events. The dominant land use (urban or agriculture) and flow regime at the time of sampling were the primary drivers of gains and losses. These exchanges were found to be most important below large diversions during low flow conditions. This highlights the need to classify inflow sources (urban or agriculture, surface or groundwater) and estimate their contributions to anticipate instream consequences of land use and water management decisions. As irrigation and water conveyance practices become more efficient, a portion of these ungaged inflows could be diminished or eliminated, thus further depleting streamflow during dry periods.

Utah↗

USGS2011

From deposition to erosion: Spatial and temporal variability of sediment sources, storage, and transport in a small agricultural watershed

The spatial and temporal variability of sediment sources, storage, and transport were investigated in a small agricultural watershed draining the Coast Ranges and Sacramento Valley in central California. Results of field, laboratory, and historical data analysis in the Willow Slough fluvial system document changes that transformed a transport-limited depositional system to an effective erosion and transport system, despite a large sediment supply. These changes were caused by a combination of factors: (i) an increase in transport capacity, and (ii) hydrologic alteration. Alteration of the riparian zone and drainage network pattern during the past ~ 150 years included a twofold increase in straightened channel segments along with a baselevel change from excavation that increased slope, and increased sediment transport capacity by ~ 7%. Hydrologic alteration from irrigation water contributions also increased transport capacity, by extending the period with potential for sediment transport and erosion by ~ 6 months/year. Field measurements document Quaternary Alluvium as a modern source of fine sediment with grain size distributions characterized by 5 to 40% fine material. About 60% of an upland and 30% of a lowland study reach incised into this deposit exhibit bank erosion. During this study, the wet 2006 and relatively dry 2007 water years exhibited a range of total annual suspended sediment load spanning two orders of magnitude: ~ 108,500 kg/km 2 /year during 2006 and 5,950 kg/km 2 /year during 2007, only 5% of that during the previous year. Regional implications of this work are illustrated by the potential for a small tributary such as Willow Slough to contribute sediment – whereas large dams limit sediment supply from larger tributaries – to the Sacramento River and San Francisco Bay Delta and Estuary. This work is relevant to lowland agricultural river–floodplain systems globally in efforts to restore aquatic and riparian functions and where water quality management includes reducing fine sediment contributions that can couple with other pollutants.

California↗

USGS2014

Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

The Edwards-Trinity aquifer, a major aquifer in the Pecos County region of western Texas, is a vital groundwater resource for agricultural, industrial, and public supply uses. Resource managers would like to better understand the future availability of water in the Edwards-Trinity aquifer in the Pecos County region and the effects of the possible increase or temporal redistribution of groundwater withdrawals. To that end, the U.S. Geological Survey (USGS), in cooperation with the Middle Pecos Groundwater Conservation District, Pecos County, City of Fort Stockton, Brewster County, and Pecos County Water Control and Improvement District No. 1, completed a comprehensive, integrated analysis of available hydrogeologic data to develop a groundwater-flow model of the Edwards-Trinity and related aquifers in parts of Brewster, Jeff Davis, Pecos, and Reeves Counties. Following calibration, the model was used to evaluate the sustainability of recent (2008) and projected water-use demands on groundwater resources in the study area.

Texas↗

USGS2020

Minnesota and Landsat

Landsat land-imaging satellites underpin public and private sector decisions in the Minnesota and across the Nation for effective adaptation to changing landscapes. Those decisions often lead to enhanced agricultural productivity, smart urban development, and sustainable forest management. Landsat also enables more accurate inland lake water-quality monitoring, increased disaster resilience and risk assessment, effective water use, more-informed climate research, and other applications.

Minnesota↗

USGS2024

The 3D Elevation Program—Supporting Michigan’s economy

High-quality elevation data are proving to be a resource of value in addressing many important economic issues in Michigan. The expanding statewide availability of current and accurate high-resolution elevation data can help support agriculture and precision farming, natural resource conservation, flood risk management, and geologic resource assessment and hazard mitigation. Water supply and quality assessment, coastal zone management, infrastructure and construction management, solar potential and other renewable energy programs, and identification of features of interest or concern such as archaeological and historical sites are other notable areas that are supported with accurate, high-resolution elevation data. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features.

Michigan↗

USGS2019

Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Efforts to restore water quality in Chesapeake Bay and its tributaries often include extensive Best Management Practice (BMP) implementation on agricultural and developed lands. These BMPs include a variety of methods to reduce nutrient and sediment loads, such as cover crops, conservation tillage, urban filtering systems, and other practices. Estimates of BMP implementation throughout the Chesapeake Bay watershed were provided for each year from 1985 through 2014 by the Chesapeake Bay Program (CBP). This dataset of BMP implementation is a compilation of actions reported by New York, Maryland, Pennsylvania, Delaware, West Virginia, Virginia, and the District of Columbia, and includes a wide array of management activities. Management actions vary among the jurisdictions and generally reflect the typical land use in each region. The amount of implementation also varies according to different priorities, reporting practices, and special programs within each jurisdiction. For example, extensive cover crop implementation was reported in Maryland whereas Pennsylvania, in general, has lower levels of BMP implementation reported on cropland. Pennsylvania and Maryland have higher levels of infiltration BMPs on developed land compared to those in Virginia. Conservation tillage BMPs accounted for the majority of reported agricultural BMP implementation in 1985. By 2014, however, a more diverse collection of agricultural BMPs was reported and conservation tillage BMPs accounted for a smaller proportion of overall reported agricultural BMP implementation. After the year 2000, land-use change BMPs, such as land retirement, pasture fencing, and forest buffers, were more commonly reported across the Chesapeake Bay watershed. Expected changes in nutrient and sediment loads in the Chesapeake Bay watershed due to BMP implementation were estimated by use of specially designed annual scenarios of the CBP Partnership Phase 5.3.2 Watershed Model. Nitrogen loads to streams were estimated to be reduced by 11 percent from 1985 to 2014 due to the implementation of BMPs. Compared with 1985, phosphorus loads were estimated to be 19 percent lower and sediment loads were estimated to be 23 percent lower by 2014 due to the effects of BMPs. Reductions in total nitrogen from 1985 to 2014 due to BMPs varied spatially across the watershed and were estimated to be as high as 42 percent in areas of the Eastern Shore of the Chesapeake Bay. Reductions in phosphorus and sediment also varied spatially, with the largest reductions occurring in the Potomac watershed upstream of Washington, D.C. and the Eastern Shore of Maryland, according to the CBP model results. Additional model scenarios were developed to estimate the effect of individual BMP types. The largest estimated reductions in total nitrogen loads on agricultural lands in 2014 were attributed to land retirement, animal waste management systems, and conservation tillage. The largest estimated reductions in total phosphorus loads on agricultural lands were attributed to animal waste management systems, pasture fencing, and phytase feed additives in 2014. The largest estimated reduction in total sediment loads on agricultural lands was attributed to conservation tillage, pasture fencing, and conservation plans. Dry ponds, wet ponds, and constructed wetlands were reported extensively throughout the watershed. These BMPs accounted for about half of the reduction in nitrogen loads from developed land to streams, half of the phosphorus reduction, and about a third of the sediment reduction.

Chesapeake Bay Watershed↗

USGS2021

Evaluation of hydrologic simulation models for fields with subsurface drainage to mitigated wetlands in Barnes, Dickey, and Sargent Counties, North Dakota

Proper identification of wetlands, along with a better understanding of the hydrology of mitigated wetlands, is needed to assist with conservation efforts aimed at maintaining the productivity and ecological function (wetland mitigation) of agricultural lands. The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Natural Resources Conservation Service, completed a study to evaluate two models for simulating hydrologic conditions in fields with subsurface drainage to mitigated wetlands at several sites in North Dakota. These two models were evaluated as possible tools for water resource managers to use for designing wetland mitigation projects in the area in the future. The Soil-Plant-Atmosphere-Water (SPAW) model simulates the daily hydrologic water budgets of agricultural landscapes by two linked routines, one for farm fields (field hydrology) and one for impoundments such as wetlands and ponds (pond model). The DRAINMOD model was used in conjunction with the SPAW model because although the SPAW model can be used to simulate the hydrology of small drainage basins containing wetlands, the SPAW model does not contain routines to simulate drainage, either subsurface drainage or surface (drainage ditches), that can directly affect the wetland hydrology. The wetlands in the study areas in this report are all downstream from and adjacent to drained agricultural fields. SPAW and DRAINMOD models were developed and calibrated at three study areas (study areas B, D, and S) to evaluate how the models simulated field-scale hydrologic characteristics and the water balance in wetlands from January 1, 2003, through December 31, 2018. The SPAW model developed for study area B included five modeled fields in the field hydrology portion of SPAW that contributed inflow to one wetland simulated in the pond model portion of SPAW. Simulated wetland water depths were most similar to water depths measured at site BWET1, with an absolute mean error of 0.10 foot and a root mean square error of 0.14 foot. Site BWET2 had slightly larger errors, with an absolute mean error of 0.22 foot and a root mean square error of 0.28 foot. Simulated water depths were similar to the pattern of measured water depths at BWET1 and BWET2 from about mid-April 2018 through about mid-September 2018, but overpredicted water depths in the fall from about mid-September 2018 through about mid-October 2018. The SPAW model developed for study area D included six modeled fields in the field hydrology portion of SPAW that contributed inflow to five wetlands connected in series in the pond model portion of SPAW. Simulated water depths compared relatively well to water depths in the five wetlands, with the absolute mean error ranging from 0.17 foot (DWET1) to 0.39 foot (DWET2), and the root mean square error ranging from 0.28 foot (DWET1) to 0.56 foot (DWET5). The SPAW model developed for study area S included one modeled field in the field hydrology portion of SPAW that contributed inflow to one wetland in the pond model portion of SPAW. Among the SPAW models developed for the three study areas, the model for study area S had the best comparison between simulated and measured water depths, with an absolute mean error of 0.06 foot and a root mean square error of 0.10 foot. DRAINMOD models were developed and calibrated at the three study areas and provided inflow from subsurface drainage discharge to the SPAW models for simulating water levels in wetlands in the study areas. The calibrated DRAINMOD model for study area B showed the variability of hydrologic processes in the modeled field throughout the wide range of hydrologic conditions from January 1, 2003, through December 31, 2018. In general, the discharge through the modeled subsurface drainage system was in the spring and early summer (April through June) most years, with little to no discharge later in the year. Although the subsurface drainage system in study area D was the most complex among the three study areas and was simplified into a uniform system within DRAINMOD, simulated water table depths at study area D correlated better to measured water table depths compared to results from the model applications at the other two study areas. Simulated water table depths had an absolute mean error of 0.30 foot and root mean square error of 0.37 foot at site DGW1 and an absolute mean error of 0.29 foot and a root mean square error of 0.34 foot at site DGW2. Although the subsurface drainage system in study area S was the simplest and the modeled field was the smallest among the three study areas, simulated water table depths at study area S did not correlate as well to measured water table depths compared to results from the model applications at the other two study areas. The SPAW and DRAINMOD model applications at the three study areas in southeast North Dakota adequately simulated the hydrologic processes for fields with subsurface drainage that are connected to adjacent wetlands. However, more measured data would be needed to fully evaluate the models throughout the range of possible climatic conditions.

North Dakota↗

USGS2011

Sulfur in the South Florida ecosystem: Distribution, sources, biogeochemistry, impacts, and management for restoration

Sulfur is broadly recognized as a water quality issue of significance for the freshwater Florida Everglades. Roughly 60% of the remnant Everglades has surface water sulfate concentrations above 1 mg l-1, a restoration performance measure based on present sulfate levels in unenriched areas. Highly enriched marshes in the northern Everglades have average sulfate levels of 60 mg l-1. Sulfate loading to the Everglades is principally a result of land and water management in South Florida. The highest concentrations of sulfate (average 60-70 mg l-1) in the ecosystem are in canal water in the Everglades Agricultural Area (EAA). Potential sulfur sourcesin the watershed are many, but geochemical data and a preliminary sulfur mass balance for the EAA are consistent with sulfur presently used in agricultural, and sulfur released by oxidation of organic EAA soils (including legacy agricultural applications and natural sulfur) as the primary sources of sulfate enrichment in the EAA canals. Sulfate loading to the Everglades increases microbial sulfate reduction in soils, leading to more reducing conditions, greater cycling of nutrients in soils, production of toxic sulfide, and enhanced methylmercury (MeHg) production and bioaccumulation. Wetlands are zones of naturally high MeHg production, but the combination of high atmospheric mercury deposition rates in South Florida and elevated sulfate loading leads to increased MeHg production and MeHg risk to Everglades wildlife and human consumers. Sulfate from the EAA drainage canals penetrates deep into the Everglades Water Conservation Areas, and may extend into Everglades National Park. Present plans to restore sheet flow and to deliver more water to the Everglades may increase overall sulfur loads to the ecosystem, and move sulfate-enriched water further south. However, water management practices that minimize soil drying and rewetting cycles can mitigate sulfate release during soil oxidation. A comprehensive Everglades restoration strategy should include reduction of sulfur loads as a goal because of the many detrimental impacts of sulfate on the ecosystem. Monitoring data show that the ecosystem response to changes in sulfate levels is rapid, and strategies for reducing sulfate loading may be effective in the near term. A multifaceted approach employing best management practices for sulfur in agriculture, agricultural practices that minimize soil oxidation, and changes to stormwater treatment areas that increase sulfate retention could help achieve reduced sulfate loads to the Everglades, with resulting benefits.

Florida↗

USGS2012

Assessing future risks to agricultural productivity, water resources and food security: How can remote sensing help?

Although global food production has been rising, the world sti ll faces a major food security challenge. Over one billion people are currently undernourished (Wheeler and Kay, 2010). By the 2050s, the human population is projected to grow to 9.1 billion. Over three-quarters of these people will be living in developing countries, in regions that already lack the capacity to feed their populations . Under current agricultural practices, the increased demand for food would require in excess of one billion hectares of new cropland, nearly equivalent to the land area of the United States, and would lead to significant increases in greenhouse gases (Tillman et al. , 2011). Since climate is the primary determinant of agricultural productivity, changes to it will influence not only crop yields, but also hydrologic balances and supplies of inputs to managed farming systems, and may lead to a shift in the geographic location of some crops . Therefore, not only must crop productivity (yield per unit of land; kg/m 2 ) increase, but water productivity (yield per unit of water or "crop per drop"; kg/m 3 ) must increase as well in order to feed a burgeoning population against a backdrop of changing dietary consumption patterns, a changing climate and the growing scarcity of water and land (Beddington, 2010). The impact from these changes wi ll affect the viability of both dryland subsistence and irrigated commodity food production (Knox, et al. , 2010a). Since climate is a primary determinant of agricultural productivity, any changes will influence not only crop yields, but also the hydrologic balances, and supplies of inputs to managed farming systems as well as potentially shifting the geographic location for specific crops . Unless concerted and collective action is taken, society risks worldwide food shortages, scarcity of water resources and insufficient energy. This has the potential to unleash public unrest, cross-border conflicts and migration as people flee the worst-affected regions to seck refuge in "safe havens", a situation that Beddington described as the "perfect storm" (2010).

Photogrammetric Engineering and Remote Sensing↗

USGS2010

Avian foods, foraging and habitat conservation in world rice fields

Worldwide, rice (Oryza sativa) agriculture typically involves seasonal flooding and soil tillage, which provides a variety of microhabitats and potential food for birds. Water management in rice fields creates conditions ranging from saturated mud flats to shallow (<30 cm) water, thereby attracting different guilds of birds. Grain not collected during harvest (i.e. waste rice) is typically the most abundant potential food of birds in rice fields, with estimates of seed mass from North America ranging from 66672 kg/ha. Although initially abundant after harvest, waste rice availability can be temporally limited. Few abundance estimates for other foods, such as vertebrate prey or forage vegetation, exist for rice fields. Outside North America, Europe and Japan, little is known about abundance and importance of any avian food in rice fields. Currently, flooding rice fields after harvest is the best known management practice to attract and benefit birds. Studies from North America indicate specific agricultural practices (e.g. burning stubble) may increase use and improve access to food resources. Evaluating and implementing management practices that are ecologically sustainable, increase food for birds and are agronomically beneficial should be global priorities to integrate rice production and avian conservation. Finally, land area devoted to rice agriculture appears to be stable in the USA, declining in China, and largely unquantified in many regions. Monitoring trends in riceland area may provide information to guide avian conservation planning in rice-agriculture ecosystems.

Waterbirds↗

USGS2015

U.S. conterminous wall-to-wall anthropogenic land use trends (NWALT), 1974–2012

This dataset provides a U.S. national 60-meter, 19-class mapping of anthropogenic land uses for five time periods: 1974, 1982, 1992, 2002, and 2012. The 2012 dataset is based on a slightly modified version of the National Land Cover Database 2011 (NLCD 2011) that was recoded to a schema of land uses, and mapped back in time to develop datasets for the four earlier eras. The time periods coincide with U.S. Department of Agriculture (USDA) Census of Agriculture data collection years. Changes are derived from (a) known changes in water bodies from reservoir construction or removal; (b) housing unit density changes; (c) regional mining/extraction trends; (d) for 1999–2012, timber and forestry activity based on U.S. Geological Survey (USGS) Landscape Fire and Resource Management Planning Tools (Landfire) data; (e) county-level USDA Census of Agriculture change in cultivated land; and (f) establishment dates of major conservation areas. The data are compared to several other published studies and datasets as validation. Caveats are provided about limitations of the data for some classes. The work was completed as part of the USGS National Water-Quality Assessment (NAWQA) Program and termed the NAWQA Wall-to-Wall Anthropogenic Land Use Trends (NWALT) dataset. The associated datasets include five 60-meter geospatial rasters showing anthropogenic land use for the years 1974, 1982, 1992, 2002, and 2012, and 14 rasters showing the annual extent of timber clearcutting and harvest from 1999 to 2012.

Data Series↗

USGS2016

Nutrients in the nexus

Synthetic nitrogen (N) fertilizer has enabled modern agriculture to greatly improve human nutrition during the twentieth century, but it has also created unintended human health and environmental pollution challenges for the twenty-first century. Averaged globally, about half of the fertilizer-N applied to farms is removed with the crops, while the other half remains in the soil or is lost from farmers’ fields, resulting in water and air pollution. As human population continues to grow and food security improves in the developing world, the dual development goals of producing more nutritious food with low pollution will require both technological and socio-economic innovations in agriculture. Two case studies presented here, one in sub-Saharan Africa and the other in Midwestern United States, demonstrate how management of nutrients, water, and energy is inextricably linked in both small-scale and large-scale food production, and that science-based solutions to improve the efficiency of nutrient use can optimize food production while minimizing pollution. To achieve the needed large increases in nutrient use efficiency, however, technological developments must be accompanied by policies that recognize the complex economic and social factors affecting farmer decision-making and national policy priorities. Farmers need access to affordable nutrient supplies and support information, and the costs of improving efficiencies and avoiding pollution may need to be shared by society through innovative policies. Success will require interdisciplinary partnerships across public and private sectors, including farmers, private sector crop advisors, commodity supply chains, government agencies, university research and extension, and consumers.

Journal of Environmental Studies and Sciences↗

USGS2003

An introduction to the San Francisco Estuary tidal wetlands restoration series

Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter “Estuary”). Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period. However, many other changes have also occurred in the Estuary concurrent with the declines of native species. Other factors that might be important in species declines include the effects of construction of upstream dams, large and small water diversions within the Sacramento-San Joaquin Delta, agricultural pesticides, trace elements from industrial and agricultural activities, and invasions of alien species. Discussions among researchers, managers, and stakeholders have identified a number of uncertainties regarding the potential benefits of tidal wetland restoration. The articles of the Tidal Wetlands Restoration Series address four major issues of concern. Stated as questions, these are: 1. Will tidal wetland restoration enhance populations of native fishes? 2. Will wetland restoration increase rates of methylation of mercury? 3. Will primary production and other ecological processes in restored tidal wetlands result in net export of organic carbon to adjacent habitats, resulting in enhancement of the food web? Will the carbon produced contribute to the formation of disinfection byproducts when disinfected for use as drinking water? 4. Will restored tidal wetlands provide long-term ecosystem benefits that can be sustained in response to ongoing physical processes, including sedimentation and hydrodynamics? Reducing the uncertainty surrounding these issues is of critical importance because tidal wetland restoration is assumed to be a critical tool for enhancement of native species and ecosystem processes in the Estuary.

California↗

USGS2009

Simulation of Water Quality in the Tull Creek and West Neck Creek Watersheds, Currituck Sound Basin, North Carolina and Virginia

A study of the Currituck Sound was initiated in 2005 to evaluate the water chemistry of the Sound and assess the effectiveness of management strategies. As part of this study, the Soil and Water Assessment Tool (SWAT) model was used to simulate current sediment and nutrient loadings for two distinct watersheds in the Currituck Sound basin and to determine the consequences of different water-quality management scenarios. The watersheds studied were (1) Tull Creek watershed, which has extensive row-crop cultivation and artificial drainage, and (2) West Neck Creek watershed, which drains urban areas in and around Virginia Beach, Virginia. The model simulated monthly streamflows with Nash-Sutcliffe model efficiency coefficients of 0.83 and 0.76 for Tull Creek and West Neck Creek, respectively. The daily sediment concentration coefficient of determination was 0.19 for Tull Creek and 0.36 for West Neck Creek. The coefficient of determination for total nitrogen was 0.26 for both watersheds and for dissolved phosphorus was 0.4 for Tull Creek and 0.03 for West Neck Creek. The model was used to estimate current (2006-2007) sediment and nutrient yields for the two watersheds. Total suspended-solids yield was 56 percent lower in the urban watershed than in the agricultural watershed. Total nitrogen export was 45 percent lower, and total phosphorus was 43 percent lower in the urban watershed than in the agricultural watershed. A management scenario with filter strips bordering the main channels was simulated for Tull Creek. The Soil and Water Assessment Tool model estimated a total suspended-solids yield reduction of 54 percent and total nitrogen and total phosphorus reductions of 21 percent and 29 percent, respectively, for the Tull Creek watershed.

North Carolina, Virginia↗

USGS2014

Northwest

Key Messages 1. Changes in the timing of streamflow related to changing snowmelt are already observed and will continue, reducing the supply of water for many competing demands and causing far-reaching ecological and socioeconomic consequences. 2. In the coastal zone, the effects of sea level rise, erosion, inundation, threats to infrastructure and habitat, and increasing ocean acidity collectively pose a major threat to the region. 3. The combined impacts of increasing wildfire, insect outbreaks, and tree diseases are already causing widespread tree die-off and are virtually certain to cause additional forest mortality by the 2040s and long-term transformation of forest landscapes. Under higher emissions scenarios, extensive conversion of subalpine forests to other forest types is projected by the 2080s. 4. While the agriculture sector’s technical ability to adapt to changing conditions can offset some adverse impacts of a changing climate, there remain critical concerns for agriculture with respect to costs of adaptation, development of more climate resilient technologies and management, and availability and timing of water.

Idaho, Oregon, Washington↗

USGS2006

Fate and effects of nitrogen and phosphorus in shallow vegetated aquatic ecosystems

Nitrate concentrations have greatly increased in streams and rivers draining agricultural regions of the Midwestern United States, increasing nitrate transport to the Gulf of Mexico has been implicated in the hypoxic conditions that threaten the productivity of marine fisheries. Increases in nitrate concentrations have been attributed to a combination of factors including agricultural expansion, increased nitrogen application rates, increased tile drainage, and loss of riparian Wetlands, These landscape-level changes have resulted in a decreased natural capacity for nitrogen uptake, removal, and cycling back to the atmosphere. Land managers are increasingly interested in using wetland construction and rehabilitation as a management practice to reduce loss of nitrate from the terrestrial systems. Yet, relatively little is known about the limnological factors involved in nitrate removal by Wetland systems. We conducted a series of studies from 1999-2000 to investigate the functional capacity of shallow, macrophyte-dominated pond wetland systems for uptake, assimilation, and retention of nitrogen (N) and phosphorus (P). We evaluated four factors that were hypothesized to influence nutrient uptake and assimilation: 1) nitrate loading rates; 2) nitrogen to phosphorus (N.P) ratios; 3) frequency of dosing/application; and 4) timing of dose initiation. Nutrient assimilation was rapid; store than 90% of added nutrients were removed from the water column in all treatments. Neither variation in N:P ratios (evaluated range, <13:1 to -114.1), frequency of application (weekly or bi-weekly), nor liming of dose initiation relative to macrophyte development (0%, 15-25%, or 75-90% maximum biomass) had significant effects on nutrient assimilation of wetland community dynamics. Maximum loading of nitrate (60 g N/m 2 2.4 g P/m 2 ) applied as six weekly doses stimulated algal communities, but inhibited macrophyte communities. Predicted shifts from a stable state of macrophyte- to phytoplankton-dominance did not occur due to nutrient additions. Macrophytes, phytoplankton, and the sediment surface were all significant factors in the removal of nitrate from the Water column. Overall, these shallow macrophyte-dominated systems provided an efficient means of removing nutrients from the water column. Construction or rehabilitation of shallow, vegetated wetlands may offer promise as land management practices for nutrient removal in agricultural watersheds.

Report↗

USGS2006

A water-budget approach to restoring a sedge fen affected by diking and ditching

A vast, ground-water-supported sedge fen in the Upper Peninsula of Michigan, USA was ditched in the early 1900s in a failed attempt to promote agriculture. Dikes were later constructed to impound seasonal sheet surface flows for waterfowl management. The US Fish and Wildlife Service, which now manages the wetland as part of Seney National Wildlife Refuge, sought to redirect water flows from impounded C-3 Pool to reduce erosion in downstream Walsh Ditch, reduce ground-water losses into the ditch, and restore sheet flows of surface water to the peatland. A water budget was developed for C-3 Pool, which serves as the central receiving and distribution body for water in the affected wetland. Surface-water inflows and outflows were measured in associated ditches and natural creeks, ground-water flows were estimated using a network of wells and piezometers, and precipitation and evaporation/evapotranspiration components were estimated using local meteorological data. Water budgets for the 1999 springtime peak flow period and the 1999 water year were used to estimate required releases of water from C-3 Pool via outlets other than Walsh Ditch and to guide other restoration activities. Refuge managers subsequently used these results to guide restoration efforts, including construction of earthen dams in Walsh Ditch upslope from the pool to stop surface flow, installation of new water-control structures to redirect surface water to sheet flow and natural creek channels, planning seasonal releases from C-3 Pool to avoid erosion in natural channels, stopping flow in downslope Walsh Ditch to reduce erosion, and using constructed earthen dams and natural beaver dams to flood the ditch channel below C-3 Pool. Interactions between ground water and surface water are critical for maintaining ecosystem processes in many wetlands, and management actions directed at restoring either ground- or surface-water flow patterns often affect both of these components of the water budget. This approach could thus prove useful in guiding restoration efforts in many hydrologically altered and managed wetlands worldwide.

Journal of Hydrology↗

USGS2022

Secretive marsh bird habitat relationships at mid-continent spring migration stopover sites

Despite several secretive marsh bird (SMB) species being listed as critically imperiled throughout the mid-continent of North America, limited information on SMB distribution and habitat use within primary migratory corridors results in uncertainty on contributions of wetlands in mid-latitude states toward their annual cycle needs. Our objectives were to quantify temporal patterns of SMB wetland occupancy during spring migration at a mid-latitude state and evaluate the relationships between SMB colonization probability and water-level management practices, and the resulting habitat conditions during spring migration. We conducted a 2-year, dynamic occupancy study (2013–2014) that included 6 rounds of repeated call-back surveys to detect the presence of 5 SMB species (i.e., Virginia rail [ Rallus limicola ], sora [ Porzana carolina ], king rail [ R. elegans ], least bittern [ Ixobrychus exilis ], and American bittern [ Botaurus lentiginosus ]) during spring (Apr–Jun) on 107 wetlands across 8 conservation areas and 4 national wildlife refuges throughout Missouri, USA. We detected sora most frequently, followed by least bittern, American bittern, Virginia rail, and king rail. Coefficient estimates indicated colonization probability for all species was positively associated with emergent vegetation cover and negatively associated with amount of open water. Open water was the only variable in the best supported model explaining American bittern site colonization, to which they were negatively associated. Virginia rail colonization had a strong positive association with vegetation height, whereas least bittern and sora site colonization were influenced positively by water depth and agriculture, respectively. Based on the habitat associations within and among SMB species identified in this study, wetland managers can tailor management strategies to optimize spring migration habitat for single- or multi-species objectives.

Missouri↗