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In this paper, the feasibility of managed aquifer recharge (MAR) for southwestern Kansas was investigated. Multiple sources of water for MAR were investigated, including rainfall-runoff from fields, use of low-flow or ephemeral rivers and streams, and use of a large regional river. Use of the Arkansas River was found to be the most viable source of water. Construction of infiltration basins in existing sand mines was found to be the best MAR alternative in this region. The requirement for the reclamation of sand mines set out by the State of Kansas fits the requirements of infiltration basins, and there exists a local ditch system that can convey Arkansas River flows to the basins with little need of new construction. The salinity of the Arkansas River is of concern. The negative impact of this could be reduced by selecting salt-tolerant crops. This investigation is relevant throughout the State of Kansas, leading to the possibility that another region would have more suitable conditions. [ABSTRACT FROM AUTHOR]

This article explores collaborative pedagogical approaches to museum exhibit design through a partnership between an anthropology class and the Blackwater Draw Museum at Eastern New Mexico University. This collaboration brought together faculty, staff, undergraduate, and graduate students to showcase the regionally relevant issues of water overuse and the conservation of the Ogallala Aquifer. Students employed anthropological research methods to develop a mini-exhibit in the Blackwater Draw Museum that incorporated data collected from the Portales and Clovis communities concerning water usage patterns of the past and present. Ultimately, this case study seeks to build a bridge between pedagogy and museum studies, showcasing opportunities for collaboration between the social sciences and regional heritage institutions. [ABSTRACT FROM AUTHOR]

Context: Conversion of native vegetation to cropland is one of the most widespread anthropogenic landscape alterations, particularly in the Great Plains region of the United States. Mule deer occur throughout the Great Plains; however, it is the south-eastern edge of their geographical distribution, and few populations coincide with dense cropland. The rapidly depleting Ogallala Aquifer supplies irrigation to row-crops throughout the region, which will likely shift towards dryland agricultural practices in the near future. Aims: We sought to understand how cropland use influences morphology, body condition indices, reproductive output, and survival of free-ranging mule deer. Methods: We accumulated a multi-year, longitudinal dataset of movement and morphology for 146 mule deer in the Texas Panhandle. We linked seasonal cropland use with observed morphology, body condition metrics, and reproductive output via linear mixed-effect modelling and assessed the influence of cropland on annual survival by using Cox proportional hazard models. Key results: Mule deer that did not use cropland at any time during the year exhibited morphological and nutritional indices similar to those that did; except body-fat percentage being greater for mature (≥4-year-old) males that used cropland. Further, cropland use did not predict survival probability. Analyses of cropland use during seasons defined by life-stage showed context-dependent nutritional benefits. Use of cropland during winter following reproduction demonstrated an increase in young (≤3-year-old) male antler size and body mass and summer crop use increased body condition for all males. Female mule deer that utilised cropland before pregnancy had increased probability of successful reproduction, demonstrating a potential capital investment strategy in reproduction. Conclusions: Cropland does not limit morphology or survival of mule deer; however, additive use of row-crops can provide a nutritional buffer and enhanced reproductive output for individuals that choose to utilise it. Implications: Our study demonstrates important population-level interactions with the environment for a species near the extent of their geographical distribution. Conversion of row-crop farming from aquifer depletion or climate shifts may not diminish mule deer populations, but these changes may alter specific habitat-nutritional health relationships that can influence population performance and future conservation efforts. The rapidly depleting Ogallala Aquifer supplies irrigation to row-crops throughout the United States Great Plains, which will likely shift towards dryland agricultural practices in the next 20 years. These areas are the fringe of the mule deer distribution and cropland serves as a nutritional buffer against naturally occurring periods of nutrient limitation. Row-crop farming conversion from aquifer depletion may not diminish mule deer populations, but these changes may alter specific habitat–nutritional relationships that influence population performance and conservation efforts. [ABSTRACT FROM AUTHOR]

The aim of this study is to visualize the historical changes in wheat and corn cropping patterns in the Texas High Plains from the perspective of geographical concentration and spatial autocorrelation. Historical county-level agricultural census data were collected from the United States Department of Agriculture and the National Agricultural Statistics Service from 1978 to 2017. Exploratory data analysis techniques were employed to examine the geographical concentration and spatial dependence of crop production among nearby locations. The results of temporal changes indicate that the harvested acres of corn and wheat tended to decrease throughout the study period. Total and irrigated harvested corn and wheat acreages were concentrated in a smaller number of counties over time while wheat production was mainly concentrated in the northern part of the region. The Moran's I test statistic for total and irrigated areas of cropland suggest that there was spatial dependence among the neighboring counties in crop production in this region. In summary, there was a spatiotemporal change in cropping patterns in the Texas High Plains over the study period. Based on the results of the spatiotemporal changes in cropping patterns in the Texas High Plains, policy makers should promote and support non-irrigated varieties of crops in order to decrease the dependence on irrigation water from the Ogallala Aquifer. [ABSTRACT FROM AUTHOR]

Climate change has increased agricultural drought risk in arid/semi-arid regions globally. One of the common adaptation strategies is shifting to more drought-tolerant crops or switching back to grassland permanently. In many drought-prone areas, groundwater dynamics play a critical role in agricultural production and drought management. This study aims to help understand how groundwater level decline affects the propensity of cropland switching back to grassland. Taking Union County of New Mexico (US) as a case study, field-scale groundwater level projections and high-resolution remote sensing data on crop choices are integrated to explore the impact of groundwater level decline in a regression analysis framework. The results show that cropland has been slowly but permanently switching back to grassland as the groundwater level in the Ogallala Aquifer continues to decline in the area. Specifically, for a one-standard-deviation decline in groundwater level (36.95 feet or 11.26 m), the average likelihood of switching back to grassland increases by 1.85% (the 95% confidence interval is [0.07%, 3.58%]). The findings account for the fact that farmers usually explore other options (such as more drought-tolerant crops, land idling, and rotation) before switching back to grassland permanently. The paper concludes by exploring relevant policy implications for land (soil) and water conservation in the long run. [ABSTRACT FROM AUTHOR]

The southern Ogallala Aquifer continues to deplete due to decades of irrigation with minimal recharge. Recently enacted regulations limiting groundwater withdrawals and the potential for farm profitability with cotton production systems indicate driving forces for increased cotton production acreage in the Northern High Plains of Texas (NHPT). This study focused on evaluating the land-use change from corn or winter wheat to cotton under irrigation and dryland conditions in the Palo Duro watershed (PDW) in the NHPT using an improved Soil and Water Assessment Tool (SWAT) model. Land-use change from irrigated corn to irrigated cotton led to reductions in average (2000–2014) annual irrigation, actual evapotranspiration (ETa), and surface runoff by 21%, 7%, and 63%, respectively. Nevertheless, the replacement of irrigated wheat with irrigated cotton caused irrigation and ETa to increase by 46% and 18%, respectively. Land-use conversion from dryland wheat to dryland cotton showed 0.1% and 15% decreases in ETa and surface runoff, respectively. More than 40% reductions in simulated cotton yields were found when the cotton planting area was moving northward to the cooler NHPT. The ongoing change in land use provided an option to lengthen the water availability of the southern Ogallala Aquifer for irrigation. [ABSTRACT FROM AUTHOR]

The Ogallala Aquifer is one of the most productive agricultural regions and is referred to as the "breadbasket of the world". It covers approximately 225,000 square miles beneath the Great Plains region spanning the states of Texas, New Mexico, Oklahoma, Kansas, Nebraska, South Dakota, Wyoming, and Colorado. The aquifer is a major water source for the region, with its use exceeding recharge. Previous studies have documented climate changes and their impacts in the region. However, this is the first study to document temperature and precipitation changes over the entire Ogallala region from 35 General Circulation Models participating in Phase 5 of the Climate Model Intercomparison Project (CMIP5). The main study objectives were (1) to provide estimates of present and future climate change scenarios for the High Plains Aquifer, (2) to translate the temperature and precipitation changes to agro-ecosystem indicator changes for Kansas using scenario funnels, and (3) to make recommendations for water resource and ecosystem managers to enable effective planning for the future availability of ecosystem services. The temperature change ranged from −4 °C to 8 °C, while the precipitation changes were between −50% to +50% over the region. This study improves the understanding of climate change on water resources and agro-ecosystems. This knowledge can be used to evaluate similar resources where the replenishment rate is slow. [ABSTRACT FROM AUTHOR]

The aim of this study is to visualize the historical changes in wheat and corn cropping patterns in the Texas High Plains from the perspective of geographical concentration and spatial autocorrelation. Historical county-level agricultural census data were collected from the United States Department of Agriculture and the National Agricultural Statistics Service from 1978 to 2017. Exploratory data analysis techniques were employed to examine the geographical concentration and spatial dependence of crop production among nearby locations. The results of temporal changes indicate that the harvested acres of corn and wheat tended to decrease throughout the study period. Total and irrigated harvested corn and wheat acreages were concentrated in a smaller number of counties over time while wheat production was mainly concentrated in the northern part of the region. The Moran’s I test statistic for total and irrigated areas of cropland suggest that there was spatial dependence among the neighboring counties in crop production in this region. In summary, there was a spatiotemporal change in cropping patterns in the Texas High Plains over the study period. Based on the results of the spatiotemporal changes in cropping patterns in the Texas High Plains, policy makers should promote and support non-irrigated varieties of crops in order to decrease the dependence on irrigation water from the Ogallala Aquifer.

The southern Ogallala Aquifer continues to deplete due to decades of irrigation with minimal recharge. Recently enacted regulations limiting groundwater withdrawals and the potential for farm profitability with cotton production systems indicate driving forces for increased cotton production acreage in the Northern High Plains of Texas (NHPT). This study focused on evaluating the land-use change from corn or winter wheat to cotton under irrigation and dryland conditions in the Palo Duro watershed (PDW) in the NHPT using an improved Soil and Water Assessment Tool (SWAT) model. Land-use change from irrigated corn to irrigated cotton led to reductions in average (2000–2014) annual irrigation, actual evapotranspiration (ETa), and surface runoff by 21%, 7%, and 63%, respectively. Nevertheless, the replacement of irrigated wheat with irrigated cotton caused irrigation and ETa to increase by 46% and 18%, respectively. Land-use conversion from dryland wheat to dryland cotton showed 0.1% and 15% decreases in ETa and surface runoff, respectively. More than 40% reductions in simulated cotton yields were found when the cotton planting area was moving northward to the cooler NHPT. The ongoing change in land use provided an option to lengthen the water availability of the southern Ogallala Aquifer for irrigation.

Climate change has increased agricultural drought risk in arid/semi-arid regions globally. One of the common adaptation strategies is shifting to more drought-tolerant crops or switching back to grassland permanently. In many drought-prone areas, groundwater dynamics play a critical role in agricultural production and drought management. This study aims to help understand how groundwater level decline affects the propensity of cropland switching back to grassland. Taking Union County of New Mexico (US) as a case study, field-scale groundwater level projections and high-resolution remote sensing data on crop choices are integrated to explore the impact of groundwater level decline in a regression analysis framework. The results show that cropland has been slowly but permanently switching back to grassland as the groundwater level in the Ogallala Aquifer continues to decline in the area. Specifically, for a one-standard-deviation decline in groundwater level (36.95 feet or 11.26 m), the average likelihood of switching back to grassland increases by 1.85% (the 95% confidence interval is [0.07%, 3.58%]). The findings account for the fact that farmers usually explore other options (such as more drought-tolerant crops, land idling, and rotation) before switching back to grassland permanently. The paper concludes by exploring relevant policy implications for land (soil) and water conservation in the long run.

The Ogallala Aquifer is one of the most productive agricultural regions and is referred to as the “breadbasket of the world”. It covers approximately 225,000 square miles beneath the Great Plains region spanning the states of Texas, New Mexico, Oklahoma, Kansas, Nebraska, South Dakota, Wyoming, and Colorado. The aquifer is a major water source for the region, with its use exceeding recharge. Previous studies have documented climate changes and their impacts in the region. However, this is the first study to document temperature and precipitation changes over the entire Ogallala region from 35 General Circulation Models participating in Phase 5 of the Climate Model Intercomparison Project (CMIP5). The main study objectives were (1) to provide estimates of present and future climate change scenarios for the High Plains Aquifer, (2) to translate the temperature and precipitation changes to agro-ecosystem indicator changes for Kansas using scenario funnels, and (3) to make recommendations for water resource and ecosystem managers to enable effective planning for the future availability of ecosystem services. The temperature change ranged from −4 °C to 8 °C, while the precipitation changes were between −50% to +50% over the region. This study improves the understanding of climate change on water resources and agro-ecosystems. This knowledge can be used to evaluate similar resources where the replenishment rate is slow.

High Plains Aquifer is one of the most important aquifers in the United States, accounting for one-fourth of total annual freshwater withdrawal, and one-fifth of crop production of some major crops. But the area above this aquifer has not been extensively researched for determining the risk of groundwater pollution. Therefore, this study was undertaken to determine the groundwater pollution potential using DRASTIC model in a Geographic Information System (GIS) environment, ESRI ArcGIS. Instead of difficulty of obtaining data, it was possible to run the DRASTIC model in ArcGIS for this aquifer. The results indicated that large portions of southwestern Texas, central Kansas, eastern Colorado, eastern Wyoming, western and north-western Nebraska were highly vulnerable to groundwater pollution whereas Oklahoma had lowest vulnerability. [Fundam Appl Agric 2019; 4(3.000): 933-942]

Groundwater levels across parts of western Kansas have been declining at unsustainable rates due to pumping for agricultural irrigation despite water‐saving efforts. Accelerating this decline is the complex agricultural landscape, consisting of both categorical (e.g., management boundaries) and numerical (e.g., crop prices) factors that drive irrigation decisions, making integrated water budget management a challenge. Furthermore, these factors frequently change through time, rendering management strategies outdated within relatively short time scales. This study uses boosted regression trees to simultaneously analyze categorical and numerical data against annual irrigation pumping to determine the relative influence of each factor on groundwater pumping across both space and time. In all, 45 key water use variables covering approximately 19,000 groundwater wells were tested against irrigation pumping from 2006 to 2016 across five categories: (1) management/policy, (2) hydrology, (3) weather, (4) land/agriculture, and (5) economics. Study results showed that variables from all five categories were included among the top 10 drivers to irrigation, and the greatest influence came from variables such as irrigated area per well, saturated thickness, soil permeability, summer precipitation, and pumping costs (depth to water table). Variables that had little influence included regional management boundaries and irrigation technology. The results of this study are further used to target the factors that statistically lead to the greatest volumes of groundwater pumping to help develop robust management strategy suggestions and achieve water management goals of the region. Plain Language Summary: Water use for crops has lowered groundwater levels in western Kansas. Past studies have shown that this water use is driven by many factors spanning policy, economics, and the physical environment. Because of this complexity, it has been difficult to fully understand which factors most drive irrigation use relative to each other. This study uses a machine‐learning model to rank the influence of 45 factors on irrigation pumping. These factors are analyzed over space (∼19,000 wells across western Kansas) and time (2006–2016). Based on this study, drivers to water use include total irrigated area, summer rainfall, and depth to the water table. Factors that have little influence include management district boundaries and irrigation system type. These results are used to make water management suggestions for the region. Key Points: The relative influence of drivers to irrigation pumping in western Kansas is modeled from 2006 to 2016 using boosted regression treesSite‐specific factors are more influential than regional policies, and weather‐related factors are more influential at longer time scalesIrrigation decision making largely follows resource availability and operation cost considerations over localized management schemes [ABSTRACT FROM AUTHOR]

Recent interest in improving soil health and agricultural sustainability recognizes the value of soil organic carbon (SOC) sequestration and nutrient cycling. The main goal of this study was to evaluate the response of various SOC and nitrogen (N) components in semiarid cropping systems transitioning from limited-irrigation to dryland and a restored grassland in the Southern High Plains of USA. Cropping systems evaluated include dryland winter wheat (Triticum aestivum L.)–sorghum (Sorghum bicolor L.)–fallow with conventional tillage (DLCTF) and no-tillage (DLNTF), limited-irrigation winter wheat–sorghum–fallow with no-tillage and cover cropping (LINTC) and no-tillage fallow (LINTF), and an undisturbed grassland (NG). Soil samples were collected from 0–15 cm and 15–30 cm depths and analyzed for SOC, total N, inorganic N, and soil microbial biomass carbon (SMBC) contents. The CO2 and N2O release during a eight-weeks long laboratory incubation were also analyzed. Results show 14% and 13% reduction in SOC and total N from 0–30 cm depth with the transition from limited-irrigation to dryland cropping systems while 51% more SOC and 41% more total N with the transition to grassland. The SMBC was 42% less in dryland cropping systems and 100% more in NG than the limited-irrigation cropping systems. However, the grassland was N limited, with 93% less inorganic N in NG compared to only 11% less in dryland cropping systems than in limited-irrigation cropping systems. The microbial respiration measured as CO2-C was highest in NG, followed by limited-irrigation and dryland cropping systems. The N2O-N release showed the lowest rate of N loss from dryland cropping systems, followed by NG and limited-irrigation cropping systems. This study demonstrated loss of SOC and N in agroecosystems transitioned to dryland crop-fallow systems, with greater magnitude of change observed in the biologically active fraction of soil organic matter. Grassland restoration could be an important strategy to increase SOC and nutrients in hot, dry, semiarid agroecosystems transitioning to dryland.

Irrigated agriculture contributes 40% of total global food production. In the US High Plains, which produces more than 50 million tons per year of grain, as much as 90% of irrigation originates from groundwater resources, including the Ogallala aquifer. In parts of the High Plains, groundwater resources are being depleted so rapidly that they are considered nonrenewable, compromising food security. When groundwater becomes scarce, groundwater withdrawals peak, causing a subsequent peak in crop production. Previous descriptions of finite natural resource depletion have utilized the Hubbert curve. By coupling the dynamics of groundwater pumping, recharge, and crop production, Hubbert-like curves emerge, responding to the linked variations in groundwater pumping and grain production. On a state level, this approach predicted when groundwater withdrawal and grain production peaked and the lag between them. The lags increased with the adoption of efficient irrigation practices and higher recharge rates. Results indicate that, in Texas, withdrawals peaked in 1966, followed by a peak in grain production 9 y later. After better irrigation technologies were adopted, the lag increased to 15 y from 1997 to 2012. In Kansas, where these technologies were employed concurrently with the rise of irrigated grain production, this lag was predicted to be 24 y starting in 1994. In Nebraska, grain production is projected to continue rising through 2050 because of high recharge rates. While Texas and Nebraska had equal irrigated output in 1975, by 2050, it is projected that Nebraska will have almost 10 times the groundwater-based production of Texas. [ABSTRACT FROM AUTHOR]

The question of how much longer groundwater can support large‐scale agricultural production is one of global significance. Many of the world's regional aquifers supporting irrigated agriculture are on a trajectory toward resource depletion. In the absence of alternative water supplies, the only viable near‐term (few to several decades) option for redirecting these heavily stressed systems on to more sustainable paths is to reduce pumping. The key issues therefore become how much should pumping be reduced to significantly extend an aquifer's lifetime and what is the likelihood of attaining a sustainable condition. We have developed a water‐balance approach to glean insights into these issues and chart pathways toward more sustainable states. An aquifer's response to pumping reductions heavily depends on the net inflow component of an aquifer's water budget, both in terms of its magnitude and how it decreases with time in response to reductions. If a reduction leads to a pumping rate that is above net inflow, the aquifer lifespan can often be extended by a factor of two or more, but depletion will be the final outcome. In contrast, if a reduction results in a pumping rate more than 10% below net inflow, a lengthy period of apparent sustainability will result. In that case, the aquifer lifespan may be extended long enough so that other options, such as large‐scale water transfers or development of more sustainable crop mixes, become viable. These concepts are demonstrated using examples based on an ongoing experiment in pumping reductions in the High Plains aquifer. Key Points: A new approach for gleaning insights into the pumping reductions required to redirect heavily stressed aquifers on to more sustainable pathsAn aquifer's response to pumping reductions heavily depends on the net inflow, both its magnitude and how it changes with timeStrategies for significantly extending aquifer lifespans are evaluated using data from an ongoing field experiment in pumping reductions [ABSTRACT FROM AUTHOR]

Eighty-three years after the Dust Bowl, residents of America's High Plains face a dire threat: their primary aquifer faces depletion, and entire sections of the country are set to run out of groundwater by the end of the century or sooner. The Ogallala Aquifer provides a significant amount of America's agricultural irrigation water and is a primary source of drinking water for Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This Article argues that policymakers should slow the Aquifer's depletion rate by implementing changes to irrigation technology, crop choice, consumer behavior, legal doctrine, and legislation. This Article recommends specific legislative and legal solutions. First, the 2020 Farm Bill should expand water conservation incentives through voluntary metering and with-drawal limits, improved irrigation equipment investments, and high-water crop subsidy eliminations. Second, policymakers should encourage long-term planning through doctrinal changes, such as changing the "safe-yield" time horizon from decades to centuries. Third, Congress should empanel a National Aquifer Commission to spearhead collective management of this precious resource. Fourth, state and federal entities should work together to coordinate both informationgathering processes and reporting on groundwater depletion. [ABSTRACT FROM AUTHOR]

As policy is developed to manage the declining Ogallala Aquifer, it is imperative to understand and manage the relationship between irrigated agriculture and human well-being in the High Plains region. We use a path analysis model to estimate the impact of the gallons of groundwater extracted for agricultural use and the percentage of irrigated farmland on Human Development Index scores for 234 High Plains counties between 1980 and 2010. Controlling for population, state, and the previous decade's Human Development Index score, we find that the prevalence of irrigated agriculture on the High Plains, as measured by the percentage of farm acres irrigated and the number of gallons of groundwater extracted, has a negligible impact on county-level human development, as measured by the Human Development Index. This suggests that policymakers may employ a range of strategies for managing irrigation withdrawals from the Ogallala Aquifer without harming the well-being of area residents. [ABSTRACT FROM AUTHOR]

Water plays an immensely important role in human life, from household to agriculture and industrial development. Due to the heavy utilization and growing demands of water, the availability of water has become a high priority. Besides sources of surface water, such as streams, lakes, and rivers, aquifers are a significant source of water on Earth through the essential groundwater supply. In the United States, the Ogallala Aquifer, a primary geologic unit of the High Plains Aquifer System, is under massive exploitation, and the water level has decreased substantially. Analysis of the saturated thickness of this aquifer is urgently essential. Thus, an interactive visual analytics tool is necessary to enable users to visualize water availability and variation overtime at multiple locations within the region. Our interactive analytic tool carries out this by first retrieving and processing the data derived from the saturated thickness of groundwater using sensors integrated into the wells. Subsequently, a visualization consisting of a contour map and a time series heatmap is created based on the sensor data, to capture the trends and patterns, such as underground water distribution, spatial and temporal changes, and sudden decreases or increases of the water level. The visual components allow users to explore observational data, which organize the visual structure in supporting making an inference to gain insights. insights. This approach can be extended to apply for any geographic areas for water-level monitoring and controlling. [ABSTRACT FROM AUTHOR]

Beneath the high plains of the Llano Estacado lies the southern extension of the Ogallala aquifer, which provides a key source of groundwater for the region. Along the eastern fringes of the Llano Estacado one can find numerous natural springs that discharge from the Ogallala formation and provide a valuable source of freshwater. Large-scale irrigation has altered hydrological conditions, which has influenced the flow of springs along the eastern escarpment. In late 2012, the author began a study of one such spring located at Silver Falls in Blanco Canyon, east of Crosbyton, Texas. The goal was to monitor the discharge of this naturally flowing spring over a period of many years to establish temporal patterns. Measurements of spring flow rates over a seven-year period did not show an appreciable reduction associated with the depletion of the Ogallala aquifer; however, discharge was found to follow a seasonal pattern of declining flow during the summer followed by a recovery starting in late fall and reaching maximum discharge during winter and early spring. Whereas seasonal variations of spring discharge can be measured precisely, the cause of these seasonal patterns is less certain. It is likely that the combined effects of seasonal groundwater extraction for irrigation and the growth and transpiration of natural vegetation contribute to the observed seasonal patterns of groundwater discharge at Silver Falls. [ABSTRACT FROM AUTHOR]

• Great Plains minnows need elevated summer spawning flows for successful recruitment. • Impoundments and groundwater development, exacerbated by drought, altered flows. • Downward streamflow trend still allows species' persistence but may become too low. • Mixed-effects regression models and Poisson regression reveal causes of alteration. • Upstream impoundments increased zero-flow days and reduced mean daily flows. Alteration of natural flow regimes from surface water and groundwater resource development has adversely impacted aquatic habitats of resident fish throughout the Great Plains. Two endangered cyprinids, Sharpnose Shiner Notropis oxyrhynchus and Smalleye Shiner N. buccula , were historically found throughout the Brazos River Basin in Texas. However, their range has been greatly reduced by construction of impoundments and stream depletion from groundwater pumping. Successful recruitment requires flowing, unobstructed river reaches of sufficient velocity to suspend semi-buoyant fertilized fish ova. The wide, shallow stream habitats the shiners utilize are now limited to the Upper Brazos River Basin upstream of Possum Kingdom Reservoir. This study assesses the relative importance of long-term climate variability, reservoir construction, and groundwater development on Upper Brazos streamflow regimes by (1) calculating flow metrics (2) evaluating groundwater-surface water interactions and long-term groundwater inflows, and (3) using mixed-effects regression models and Poisson regression. Results show that fish habitat has been threatened through several impacted hydrologic processes: (1) groundwater development has resulted in reduced mean daily flows, peak flows, and zero-flow days, (2) upstream impoundments have increased zero-flow days and reduced mean daily flows, and (3) lower mean daily flows and peak flows now occur during droughts, suggesting water resource development—particularly after 1970—has exacerbated drought effects. We illustrate this approach using the Upper Brazos River Basin; however, the methodology applied can inform management actions to maintain spawning flows for streams in similar altered basins. [ABSTRACT FROM AUTHOR]

Groundwater from the Ogallala-High Plains Aquifer supports one of the most productive agriculture regions in the world. Yet, despite nearly 40 years of policies designed to conserve and sustain this vital resource, the Aquifer continues to be depleted at an unsustainable rate. We integrate propositions from treadmill of production theory and ecological modernization theory to develop a structural model, focusing especially on the role of technological modernization as a key mechanism motivating depletion. A time-sequenced path analysis of all counties in the Ogallala Aquifer region reveals that groundwater depletion has a strong internal momentum characteristic of an agricultural production treadmill. Technological modernization promotes depletion through Jevon's Paradox. Increases in water efficiency—more crop per drop—are associated with less groundwater consumption, but more extensive deployments of irrigation infrastructures overwhelm the beneficial effects of increased water efficiency. An income-subsidy mechanism supports the treadmill dynamic. Agricultural production and increased water efficiency do not influence incomes. Instead, incomes are influenced mainly by expansions of irrigation technologies, which generates subsidies, and this dynamic puts further "spin" on the treadmill. The implications of the findings for theory and policy are discussed. [ABSTRACT FROM AUTHOR]

Decreased groundwater levels of the Ogallala Aquifer have increased interest in simulating crop responses to deficit irrigation strategies to evaluate the sustainable irrigation management for profitable crop production. However, the ability of widely used simulation models to accurately represent crop responses to deficit irrigation is not thoroughly evaluated. Therefore, the objective of this research was to evaluate the efficacy of the plant stress algorithms in Soil and Water Assessment Tool (SWAT) to simulate corn (Zea mays L.) responses to deficit irrigation treatments. Results showed simulated corn leaf area index (LAI), biomass, and yield under full irrigation scenarios matched measured data reasonably well at two study sites. However, clear reductions in model performance statistics for corn LAI simulations were found under the deficit irrigation scenarios for both sites (Nash- Sutcliffe efficiency [NSE] <0.49; percent bias [PBIAS] >14%). Additionally, considerable overestimation of yield occurred in the deficit irrigation scenarios for both sites (PBIAS >30% in most years). The unsatisfactory results from simulations of both LAI and yield under the deficit irrigation scenarios suggested potential deficiencies of the plant stress algorithms in SWAT. Two apparent limitations of the plant stress algorithms were (i) the equation for computing actual plant growth factor using a singular stress factor, determined by the maximum value of four plant stress factors of water, temperature, nitrogen, and phosphorus, and (ii) the computed actual plant growth factor only adjusting potential daily accumulations of LAI rather than modifying the shape of the LAI development by adjusting related parameters. [ABSTRACT FROM AUTHOR]

Highlights • Water productivity for maize increased under higher irrigation capacity. • Water productivity for grain sorghum was greater than for winter wheat. • Income from dryland wheat was greater than from irrigated wheat. • Maize was more profitable when grown under full than deficit irrigation conditions. • Income from growing maize may not last long due to rapidly depleting groundwater. Abstract Crop water productivity and return after variable cost for three major crops (winter wheat, grain sorghum and maize) in the southwest Kansas were evaluated based on simulated yield using the Decision Support System for Agrotechnology Transfer - Cropping System Model (DSSAT-CSM). Winter wheat and grain sorghum were treated with four irrigation capacities (ICs) (zero, 1.7, 2.5 and 5 mm/day) and an automatic irrigation (irrigation when required). Maize was treated with three ICs (0, 2.5 and 5 mm/day) and an automatic irrigation. Long-term simulations showed that average winter wheat, grain sorghum and maize yields can be stabilized under 1.7–2.5, 2.5 and 5 mm/day ICs with corresponding irrigation of 100–150, 100–250 and 450–500 mm, respectively. The crop water productivities of winter wheat, grain sorghum and maize ranged from 9.8 to 11.8, 12.8–15.0 and 4.2–19.1 kg/ha/mm, respectively. Maize was found to be profitable when grown under both deficit and full irrigation conditions although optimal irrigation application for maize substantially increased the net return after variable cost (RAVC). The median net return after variable cost for rainfed wheat ($252/ha) and grain sorghum ($180/ha) was greater than that for irrigated wheat ($169–$192/ha) and grain sorghum ($104–$110/ha). The RAVC for wheat and grain sorghum did not rise with increase in irrigation and IC, whereas the RAVC for maize increased with irrigation and IC. The lowest and highest RAVC for maize corresponded to IC of 0 ($16/ha) and 5 mm/day ($530/ha). However, this income from growing maize under higher IC may not last long due to rapidly depleting groundwater levels in the underlying Ogallala aquifer. Therefore, the short-term benefits of growing maize under higher ICs need to be compared with the long-term environmental impact, food security and employment opportunities including sustaining the growing municipal and industrial water needs. [ABSTRACT FROM AUTHOR]

The article argues for Kansas to modify its existing water banking program to help extend the life of aquifers in Kansas. Topics discussed include current status of water and water law in Kansas; fixing prices for water right use, and empowering Kansas water banks to purchase and lease water rights; and hydrological structure of Ogallala aquifer.

The imminent depletion of the Ogallala Aquifer demands innovative cropping alternatives. Even though the benefits of cover crops are well recognized, adoption has been slow in the Southern High Plains (SHP) of the United States because of concerns that cover crops withdraw soil water to the detriment of the summer crops. This small plot experiment tested the interacting effects—production, soil water depletion of the cover crops, and subsequent teff [Eragrostis tef (Zucc.) Trotter] summer hay crops—of irrigation and tillage management with five cover crop types to identify low-risk cover crop practices in the drought-prone SHP. Dryland rye (Secale cereale L.) produced modest forage biomass (>1000 kg ha−1), even in a dry year, but it was found that light irrigation should be used to ensure adequate forage supply (>1200 kg ha−1) if winter grazing is desired. No-till management and timely termination of the winter cover crops were crucial to reducing the negative impact of winter crops on summer teff production. The results indicated no detriment to soil water content that was attributable to planting no-till cover crops compared with the conventional practice of winter fallow. Therefore, producers could take advantage of the soil-conserving attributes of high-quality winter forage cover crops without experiencing significant soil water depletion.

A bivariate kernel density estimation (KDE) method was utilized to develop a stochastic framework to assess how agricultural droughts are related to unfavorable meteorological conditions. KDE allows direct estimation of the bivariate cumulative density function which can be used to extract the marginal distributions with minimal subjectivity. The approach provided excellent fits to bivariate relationships between the standardized soil moisture index (SSMI) computed at three- and six-month accumulations and standardized measures of precipitation (P), potential evapotranspiration (PET), and atmospheric water deficit (AWD = P − PET) at 187 stations in the High Plains region of the US overlying the Ogallala Aquifer. The likelihood of an agricultural drought given a precipitation deficit could be as high as 40–65% within the study area during summer months and between 20–55% during winter months. The relationship between agricultural drought risks and precipitation deficits is strongest in the agriculturally intensive central portions of the study area. The conditional risks of agricultural droughts given unfavorable PET conditions are higher in the eastern humid portions than the western arid portions. Unfavorable PET had a higher impact on the six-month standardized soil moisture index (SSMI6) but was also seen to influence three-month SSMI (SSMI3). Dry states as defined by AWD produced higher risks than either P or PET, suggesting that both of these variables influence agricultural droughts. Agricultural drought risks under favorable conditions of AWD were much lower than when AWD was unfavorable. The agricultural drought risks were higher during the winter when AWD was favorable and point to the role of soil characteristics on agricultural droughts. The information provides a drought atlas for an agriculturally important region in the US and, as such, is of practical use to decision makers. The methodology developed here is also generic and can be extended to other regions with considerable ease as the global datasets required are readily available.

A fit for purpose (FFP) framework has been developed to evaluate the suitability of brackish water resources for various competing uses. The suitability or the extent of unsuitability for an intended use is quantified using an overall compatibility index (OCI). The approach is illustrated by applying it to evaluate the feasibility of the Dockum Hydrostratigraphic Unit (Dockum-HSU) as a water supply alternative in the Southern High Plains (SHP) region of Texas. The groundwater in Dockum-HSU is most compatible for hydraulic fracturing uses. While the water does not meet drinking water standards, it can be treated with existing desalination technologies over most of the study area, except perhaps near major population centers. The groundwater from Dockum-HSU is most compatible for cotton production, but not where it is currently grown. It can be a useful supplement to facilitate a smoother transition of corn to sorghum cropping shifts happening in parts of the SHP. Total Dissolved Solids (TDS), Sodium Absorption Ratio (SAR), sodium, sulfate, and radionuclides are major limiting constituents. Dockum-HSU can help reduce the freshwater footprint of the Ogallala Aquifer in the SHP by supporting non-agricultural uses. Greater regional collaboration and more holistic water management practices are however necessary to optimize brackish groundwater use.

Agricultural production in the Great Plains provides a significant amount of food for the United States while contributing greatly to farm income in the region. However, recurrent droughts and expansion of crop production are increasing irrigation demand, leading to extensive pumping and attendant depletion of the Ogallala aquifer. In order to optimize water use, increase the sustainability of agricultural production, and identify best management practices, identification of food–water conflict hotspots in the Ogallala Aquifer Region (OAR) is necessary. We used satellite remote sensing time series of agricultural production (net primary production, NPP) and total water storage (TWS) to identify hotspots of food–water conflicts within the OAR and possible reasons behind these conflicts. Mean annual NPP (2001–2018) maps clearly showed intrusion of high NPP, aided by irrigation, into regions of historically low NPP (due to precipitation and temperature). Intrusion is particularly acute in the northern portion of OAR, where mean annual TWS (2002–2020) is high. The Oklahoma panhandle and Texas showed large decreasing TWS trends, which indicate the negative effects of current water demand for crop production on TWS. Nebraska demonstrated an increasing TWS trend even with a significant increase of NPP. A regional analysis of NPP and TWS can convey important information on current and potential conflicts in the food–water nexus and facilitate sustainable solutions. Methods developed in this study are relevant to other water-constrained agricultural production regions.

The Ogallala Aquifer extends beneath eight states in the Great Plains region of North America. It stretches from Texas to South Dakota and is among the largest aquifers in the world. In Texas, extraction of groundwater, primarily for cropland irrigation, far exceeds recharge resulting in a significant decline of the water table. In the Texas High Plains, this decline prompted restrictions set by a local water conservation agency in 2009 stating that in 50 years about 50% of the saturated thickness of the Ogallala Aquifer should be preserved. However, this restriction only addressed the quantity and not the quality of the remaining water. The quality of water extracted from the Ogallala Aquifer has been observed to change over time, especially over the length of a crop’s growing season. We measured water quality over a three-year period using an electrical conductivity sensor and measured depth to water at 20 locations across five counties in the Texas High Plains. Results show that when wells are actively pumping, water quality can change in complex and unpredictable ways. In some cases, water quality declined and in others water quality improved. This result has prompted us to further investigate the mechanisms involved in observed seasonal water quality changes.

The Ogallala Aquifer is one of the largest freshwater aquifers in the world. It acts as a valuable resource in agriculture, animal production, and public water supplies across eight Great Plains states. However, with high irrigation demand, low recharge rates across most of the region, and extreme climate variability, the Ogallala Aquifer has become an exhaustible resource. Some areas of the Ogallala Aquifer region (OAR) are challenged with the transition of irrigated crop systems to dryland production and how to select sustainable management practices to conserve water and soil health. The main goal of this review is to identify the role of soil health in adapting to extreme climate variability with reduced irrigated water. We will describe the OAR, define roles of microorganisms and soil organic matter (SOM) in soil health, outline potential soil health indicators and common methodology, and discuss the importance of soil health assessments and management challenges facing the OAR. Information on this arid to semiarid region will aid in future soil health assessments in regions facing similar challenges. [ABSTRACT FROM AUTHOR]

Depletion of the Ogallala aquifer in the U.S. Great Plains demands information on water usage in forage-fed beef production. We compared a summer grazing system for beef steers consisting of warm-season grasses vs. grasses growing with lucerne (Medicago sativa L.). The water footprint averaged 39 and 26 m3 of water kg−1 of beef liveweight gain, respectively, when water included rainfall, irrigation, and livestock drinking. Including lucerne reduced the water footprint of beef weight gain thanks to its ability to alleviate protein deficiency in the associated grasses, thus diminishing an important source of inefficiency in converting feed to meat. [ABSTRACT FROM AUTHOR]

Water is an essential natural resource. Among many stressors, altered climate is exerting pressure on water resource systems, increasing its demand and creating a need for vulnerability assessments. The overall objective of this study was to develop a novel tool that can translate a theoretical concept (vulnerability of water resources (VWR)) to an operational framework mainly under altered temperature and precipitation, as well as for population change (smaller extent). The developed tool had three stages and utilized a novel systems thinking approach. Stage-1: Translating theoretical concept to characteristics identified from studies; Stage-2: Operationalizing characteristics to methodology in VWR; Stage-3: Utilizing the methodology for development of a conceptual modeling tool for VWR: WR-VISTA (Water Resource Vulnerability assessment conceptual model using Indicators selected by System’s Thinking Approach). The specific novelties were: 1) The important characteristics in VWR were identified in Stage-1 (target system, system components, scale, level of detail, data source, frameworks, and indicator); 2) WR-VISTA combined two vulnerability assessments frameworks: the European’s Driver–Pressure–State–Impact–Response framework (DPSIR) and the Intergovernmental Panel on Climate Change’s framework (IPCC’s); and 3) used systems thinking approaches in VWR for indicator selection. The developed application was demonstrated in Kansas (overlying the High Plains region/Ogallala Aquifer, considered the “breadbasket of the world”), using 26 indicators with intermediate level of detail. Our results indicate that the western part of the state is vulnerable from agricultural water use and the eastern part from urban water use. The developed tool can be easily replicated to other regions within and outside the US. [ABSTRACT FROM AUTHOR]

The Ogallala Aquifer extends beneath eight states in the Great Plains region of North America. It stretches from Texas to South Dakota and is among the largest aquifers in the world. In Texas, extraction of groundwater, primarily for cropland irrigation, far exceeds recharge resulting in a significant decline of the water table. In the Texas High Plains, this decline prompted restrictions set by a local water conservation agency in 2009 stating that in 50 years about 50% of the saturated thickness of the Ogallala Aquifer should be preserved. However, this restriction only addressed the quantity and not the quality of the remaining water. The quality of water extracted from the Ogallala Aquifer has been observed to change over time, especially over the length of a crop's growing season. We measured water quality over a three-year period using an electrical conductivity sensor and measured depth to water at 20 locations across five counties in the Texas High Plains. Results show that when wells are actively pumping, water quality can change in complex and unpredictable ways. In some cases, water quality declined and in others water quality improved. This result has prompted us to further investigate the mechanisms involved in observed seasonal water quality changes. [ABSTRACT FROM AUTHOR]

We introduce a model that incorporates two important elements to estimating welfare gains from groundwater management: stochasticity and a spatial stock externality. We estimate welfare gains resulting from optimal management under uncertainty as well as a gradual stock externality that produces the dynamics of a large aquifer being slowly exhausted. This groundwater model imposes an important aspect of a depletable natural resource without the extreme assumption of complete exhaustion that is necessary in a traditional single cell (bathtub) model of groundwater extraction. Using dynamic programming, we incorporate and compare stochasticity for both an independent and identically distributed as well as a Markov chain process for annual rainfall. We find that the spatial depletion of the aquifer is significant to welfare gains for a parameterization of a section of the Ogallala Aquifer in Kansas, ranging from 2.9% to 3.01%, which is larger than those found previously over the region. Surprisingly, the inclusion of stochasticity in rainfall increases welfare gains only slightly. [ABSTRACT FROM AUTHOR]

Groundwater reliant and agriculturally dominant environments (GRADEs) utilize exhaustible aquifer resources to supply food and fiber demands. The sustainability of these GRADES is threatened by over‐exploitation of fresher groundwater resources. There is an interest in exploring deeper brackish groundwater resources to sustain agricultural based economies in these regions. Using the southern high plains of Texas (SHP) as a test‐bed, the interlinkages between food‐energy‐water on improving water resiliency through brackish groundwater development is explored. Three scenarios—(1) direct use of deeper formations; (2) blending deeper and shallower groundwaters and 3) desalination of blended resources were evaluated in a spatially explicit manner. The results indicate that direct reuse of deeper water is possible over 30% of the study area, but it is not available in areas of critical need. The parameters limiting the suitability of deeper groundwater for agriculture in the order of decreasing importance are EC > TDS > SAR > B > Na > Cl. Simple blending of water from deeper and shallower aquifers improve water quality over roughly 900,000 acres. While blending greatly reduces the specific ion toxicities caused by sodium absorption ratio (SAR) and boron (B), the limitations of total dissolved solids (TDS) cannot be overcome. The over‐burden pressures in the deeper confined aquifer somewhat alleviate the blending energy requirements, especially in the southern portions of SHP. Desalination increases the energy requirements by several fold and is not suitable to sustain current agricultural practices which are focused mostly on lower valued staple crops. Using desalinated water for municipal and industrial uses can help ameliorate the stresses on the Ogallala Aquifer and enhance its longevity. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 21–36, 2018 Novelty or Significance: The study is focused on the linkages between food, energy and water in groundwater dependent agricultural economies. Using the Southern High Plains of Texas as a test‐bed, the work evaluates whether a deeper brackish groundwater resource (Dockum geological unit) can be used to augment water supplies to sustain intensive agricultural production. The study identifies various factors that limit the use of this deeper resource and quantifies the energy footprint associated with three progressively complex approaches to improve water resiliency in the region and prolong the life of the Ogallala Aquifer. [ABSTRACT FROM AUTHOR]

Geochemistry and lithium isotope compositions (δ 7 Li) of Permian Basin produced water and potable groundwater from overlying aquifers at an enhanced oil recovery (EOR) site in Gaines County, northwest Texas, are used to evaluate the effects of brine-groundwater-rock interactions, identify sources of dissolved solids, and characterize fluid flow and mixing processes. δ 7 Li values (per mil deviations from the LSVEC standard 7 Li/ 6 Li ratio) for produced water from dolostones of the San Andres Formation ranged from +10.9 to +15.6‰ and fall within the range of formation waters from other sandstone/carbonate reservoir rocks in North America, Europe and the Middle East. These differ from produced waters from hydraulically fractured shales from the U.S. Appalachian Basin, including the Marcellus Shale, which tend to have lower δ 7 Li values and higher Li/Cl, possibly indicating greater interaction with a terrigenous component. The San Andres produced water chemistry and Li isotope ratios are consistent with Neogene meteoric water interacting with marine and continentally-derived evaporites (e.g., portions of the Guadalupian Salado Formation), as well as other terrestrial sources along the flow path. Groundwater from the Triassic Dockum Group-Santa Rosa aquifer (δ 7 Li range of +20.6 to +23.5‰) is isotopically distinct from waters from the overlying Ogallala Formation (+10.6 to +16.5‰) and the deeper San Andres Formation, indicative of hydrologic isolation from both meteoric recharge and from deeper brines in the field area. In addition to tracking groundwater-brine mixing and water-rock interaction, temporal changes in the δ 7 Li composition of deep groundwater in the study area has potential use in the early detection of upward or injection-induced brine migration, prior to its incursion into the sensitive overlying Ogallala aquifer. [ABSTRACT FROM AUTHOR]

Texas High Plains (THP), one of the most important food and fiber producing regions in the Ogallala Aquifer Region, currently faces rapid decline of groundwater levels. Predicted climate extremes and high temporal variability in growing season precipitation may require growers to pump more groundwater from the Ogallala Aquifer to meet higher crop water demand. The Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM) is a widely used crop simulation tool for evaluating impacts of different water and crop management practices, including irrigation on crop yield and water use efficiency. In this study, CROPGRO-Cotton module of the DSSAT was calibrated and validated using 2000, 2001, 2002, and 2010 irrigated lysimeter field data managed by the USDA-ARS (United States Department of Agriculture - Agricultural Research Service) Conservation and Production Research Laboratory at Bushland, TX. The lysimeter field consisted of four equal plots designated as NE, SE, NW, and SW. Crop growth characteristics including leaf area index (LAI), above ground biomass (AGB), evapotranspiration (ET), soil moisture, and lint yield of 2000-NE, 2000-SE, and 2001-NE, were used for calibration and 2002-NE, 2010-NE, and 2010-SE were used for validation. The calibrated and validated model was used to simulate the long term (1924-2012) crop yield and seasonal crop ET. During the calibration process, some of the cultivar and ecotype parameters that influence LAI, AGB, and lint yield were adjusted for better statistical results. Measured and simulated LAI, AGB, ET, soil moisture, and lint yield showed good agreement during calibration and validation as indicated by performance statistics such as r 2 from 0.70 to 0.82, and percent error (PE) = −0.85 to 17.3% for LAI; r 2 = 0.89 to 0.95, and PE = −7.36 to −13.66% for AGB; and r 2= 0.90 to 0.94, and PE = 3.20 to 3.44% for ET during calibration and validation, respectively. The model underestimated ET during peak vegetative growth and development stage except in some circumstances. The calibrated and validated model was able to simulate lint yield and seasonal ET during a long term (1924-2012) historic period for Bushland, TX, under irrigated conditions. The calibrated model could be used to schedule ET based irrigation management practices in the THP and to estimate future ET for other modeling experiments. [ABSTRACT FROM AUTHOR]

The Ogallala Aquifer is the only reliable source of freshwater in the Southern High Plains (SHP) and is used extensively to build a strong agricultural economy with a significant impact on global food security. Groundwater models capable of simulating human-hydrologic-climate interactions are crucial to guide future water management and policy planning endeavors in this water stressed region. A well-defined conceptual model is a necessary first-step in that direction. Conceptual modeling should not be limited to compiling necessary datasets but must also focus on generating critical insights pertaining to human-climate-aquifer interactions especially when the emphasis is on guiding future policy. Model integration and the feasibility of coupling available tools and techniques must be explored to fill-in critical data gaps and capture interactions with a high degree of fidelity. A conceptual modeling framework built on this premise was applied to guide an on-going regional-scale groundwater modeling study in the SHP. The paucity of groundwater production data was identified as a major limiting factor. A linked Decision Support System for Agro-Technology Transfer (DSSAT) model with MODFLOW is expected to be useful in obtaining groundwater production estimates through detailed crop modeling. The time to recharge is long (decades to centuries) over most of the SHP. As such, the coupling of watershed and groundwater models is perhaps not warranted. Baseflow separation indicated that surface water-groundwater interactions have diminished over the last six decades due to declining water tables. While groundwater withdrawals generally increased during droughts, the aquifer also buffered climatic influences at some locations. [ABSTRACT FROM AUTHOR]

The purpose of this research is to provide input into the water planning process for select subareas in southwest Kansas. Stakeholder input suggests that a reduction in groundwater use may be desirable in order to preserve the Ogallala Aquifer and extend its economic contribution to both the producer and the regional economy. In an endeavor to define the benefits and costs of water conservation policy, this research estimates measures of producer net profits and regional value added and places a monetary value on the conserved groundwater. The results of the models that assume the goal is to maximize producer profits, suggest that the Local Enhanced Management Areas (LEMAs) framework of groundwater management will provide benefits to both the agricultural producer and rural communities. Subarea 1 will receive the greatest benefit, increasing cumulative net revenue by 6.3%, while Subareas 2 and 3 increase cumulative net revenue by 2.1% and 2.7%, respectively. The results suggest that generally, the rural economy receives as much, if not more, benefits from groundwater conservation than the agricultural producer. Subareas 1, 2, and 3 generated 8.3%, 2.7%, and 1.8%, respectively, more cumulative value added under the LEMA scenario as compared to the Status Quo scenario. If Subarea 3 were to manage their groundwater based on implementing a LEMA plan and maximizing value added, cumulative value added would increase from a 1.8% gain to an increase of 18.7%. [ABSTRACT FROM AUTHOR]

We used Landsat imagery to examine surface-water dynamics over the past 27 years in 39 salt lakes (salinas) of the Southern High Plains of the U.S. These groundwater- and precipitation-fed wetlands are regionally unique habitats with high salt concentrations and halophytic biota that may be vulnerable to hydrological changes from groundwater extraction for agriculture coupled with drought. We documented amounts and occurrences of water within the 39 salinas, comparing summer and winter (representing periods of high and low groundwater demand, respectively) in 1986-2013. During this span in our study area, total and irrigated cropland acreage increased, and the saturated thickness of the Ogallala Aquifer decreased by ~18.3%. There was variation in inundation frequency by salina, with two never holding water during our study. A third of the salinas went dry at least once, slightly more in summer than winter. Occurrence of water was not simply a function of basin size or to depth to the aquifer. These wetlands are being impacted by human changes to the landscape that are diminishing groundwater inputs, effectively creating novel wetlands that are now primarily supplied by precipitation rather than groundwater, with altered hydrological and ecological traits that may exacerbate regional vulnerability to climate change. [ABSTRACT FROM AUTHOR]

The impact of water policy on conserving the Ogallala Aquifer in Groundwater Management District 3 (GMD3) in southwestern Kansas is analyzed using a system-level theoretical approach integrating agricultural water and land use patterns, changing climate, economic trends, and population dynamics. In so doing, we (1) model the current hyper-extractive coupled natural-human (CNH) system, (2) forecast outcomes of policy scenarios transitioning the current groundwater-based economic system toward more sustainable paths for the social, economic, and natural components of the integrated system, and (3) develop public policy options for enhanced conservation while minimizing the economic costs for the region's communities. The findings corroborate previous studies showing that conservation often leads initially to an expansion of irrigation activities. However, we also find that the expanded presence of irrigated acreage reduces the impact of an increasingly drier climate on the region's economy and creates greater long-term stability in the farming sector along with increased employment and population in the region. On the negative side, conservation lowers the net present value of farmers' current investments and there is not a policy scenario that achieves a truly sustainable solution as defined by Peter H. Gleick. This study reinforces the salience of interdisciplinary linked CNH models to provide policy prescriptions to untangle and address significant environmental policy issues. [ABSTRACT FROM AUTHOR]