Marios Sophocleous

University of Kansas | KU · Kansas Geological Survey

The Ogallala Formation of Miocene/Pliocene age is present over a large area of the Great Plains in the central US. The formation is composed of mostly clastic material eroded and transported eastward from the Rocky Mountains by eastward flowing rivers and streams. It contains the life-giving water that supports the population and farming activities...

The water-level decline of the High Plains/Ogallala aquifer is one of the largest water management concerns in the United States. The economy and livelihood of people living in that vast region depend almost exclusively on water extracted from that aquifer. A debate about its future is ongoing, and questions remain as to how best to conserve the gr...

An aquifer system, when perturbed, has a tendency to evolve to a new equilibrium, a process that can take from just a few seconds to possibly millions of years. The time scale on which a system adjusts to a new equilibrium is often referred to as "response time" or "lag time." Because groundwater response time affects the physical and economic viab...

The sustainability of crucial earth resources, such as groundwater, is a critical issue. We consider groundwater sustainability a value-driven process of intra- and intergenerational equity that balances the environment, society, and economy. Synthesizing hydrogeological science and current sustainability concepts, we emphasize three sustainability...

A method of estimating groundwater recharge, based on water-balance components using the SWAT-MODFLOW model (an integrated surface water-groundwater model), is described. A multi-reservoir storage routing module is suggested instead of a single storage routing module in SWAT; this represents a more realistic delay in the travel of water through the...

Groundwater evaporation can play an important role in crop-water use where the water table is shallow. Lysimeters are often used to quantify the groundwater evaporation contribution influenced by a broad range of environmental factors. However, it is difficult for such field facilities, which are operated under limited conditions within limited tim...

Understanding and explaining surface tension and capillarity are not easy tasks. In this manuscript, an attempt is made to explain such phenomena for the generally educated professional. Following a conceptual explanation of the molecular basis of surface tension, it is shown that the true force exerted by the solid walls of a capillary tube on the...

Aquifers are the primary source of drinking water for up to two billion people. To avoid overexploitation, lengthy renewal periods of some aquifers must be taken into account.

In general, there have been various methods of estimating groundwater recharge such as baseflow separation approaches, water budget analyses based on lumped conceptual models, and the water table fluctuation method (WTF) by using data from groundwater monitoring wells. However, groundwater recharge rates show spatial-temporal variability due to cli...

Use of secondary-treated municipal wastewater for crop irrigation south of Dodge City, Kansas, where the soils are mainly of silty clay loam texture, has raised a concern that it has resulted in high nitrate-nitrogen concentrations (10–50 mg/kg) in the soil and deeper vadose zone, and also in the underlying deep (20–45 m) ground water. The goal of...

Groundwater is an important component of the freshwater system and its role is becoming even more prominent as the more accessible surface water resources become increasingly exploited to support increasing populations and development. Yet despite its significance, there has been comparatively little research conducted on groundwater relative to su...

The US High Plains aquifer, one of the largest freshwater aquifer systems in the world, continues to decline, threatening the long-term viability of the region's irrigation-based economy. The eight High Plains States take different approaches to the development and management of the aquifer based on each state's body of water laws that abide by dif...

The use of treated wastewater for irrigation of crops could result in high nitrate-nitrogen (NO(3)-N) concentrations in the vadose zone and ground water. The goal of this 2-yr field-monitoring study in the deep silty clay loam soils south of Dodge City, Kansas, was to assess how and under what circumstances N from the secondary-treated, wastewater-...

SWAT, a physically-based, hydrological model simulates crop growth, soil water and groundwater movement, and transport of sediment and nutrients at both the process and watershed scales. While the different versions of SWAT have been widely used throughout the world for agricultural and water resources applications, little has been done to test the...

Conflicts between ecosystems and human needs for fresh water are increasing. The purpose of this paper is to raise awareness in the hydrogeologic community of environmental flows (EFs) and to address the major challenges involved in their protection. Ground water is a key component of EFs, and therefore hydrogeologists are called upon to get involv...

1] Past land use changes have greatly impacted global water resources, with often opposing effects on water quantity and quality. Increases in rain-fed cropland (460%) and pastureland (560%) during the past 300 years from forest and grasslands decreased evapotranspiration and increased recharge (two orders of magnitude) and streamflow (one order of...

Static pore water pressures in confined aquifers vary in response to ground surface loading changes, including precipitation and evaporation. Under certain hydrogeological conditions such aquifers can function as giant natural weighing lysimeters, referenced here as ‘geological weighing lysimeters’. The extent of the land area ‘weighed’ increases w...

Sustainability and sustainable pumping are two different concepts that are often used interchangeably. The latter term refers to a pumping rate that can be maintained indefinitely without mining an aquifer, whereas the former term is broader and concerns such issues as ecology and water quality, among others, in addition to sustainable pumping. Ano...

Sustainable use of groundwater must ensure not only that the future resource is not threatened by overuse, but also that natural environments that depend on the resource, such as stream baseflows, riparian vegetation, aquatic ecosystems, and wetlands are protected. To properly manage groundwater resources, accurate information about the inputs (rec...

One of the most pressing global issues currently facing mankind is the increase in world population and its impact on the availability of freshwater. Recent estimates of water stocks and flows through the world's hydrologic cycle and their spatiotemporal variability illustrate the nature of current and projected water disparities throughout the wor...

Ground-water chemistry and water levels at three levels in a well nest were monitored biweekly for two and a half years in a shallow unconfined floodplain aquifer in order to study the dynamics of such shallow aquifers. The aquifer, in northeastern Kansas, consists of high porosity, low hydraulic conductivity fine-grained sediments dominated by sil...

This paper presents the results of a comprehensive modeling study of surface and groundwater systems, including stream–aquifer interactions, for the Wet Walnut Creek Watershed in west-central Kansas. The main objective of this study was to assess the impacts of watershed structures and irrigation water use on streamflow and groundwater levels, whic...

Increased irrigation in Kansas and other regions during the last several decades has caused serious water depletion, making the development of comprehensive strategies and tools to resolve such problems increasingly important. This paper makes the case for an intermediate complexity, quasi-distributed, comprehensive, large-watershed model, which fa...

This paper presents a synthesis of water sustainability issues from the hydrologic perspective. It shows that safe yield is a flawed concept and that sustainability is an idea that is broadly used but perhaps not well understood. In general, the sustainable yield of an aquifer must be considerably less than recharge if adequate amounts of water are...

We developed a model code to simulate a watershed's hydrology and the hydraulic response of an interconnected stream-aquifer system, and applied the model code to the Lower Republican River Basin in Kansas. The model code links two well-known computer programs: MODFLOW (modular 3-D flow model), which simulates ground water flow and stream-aquifer i...

The objective of this article is to develop and implement a comprehensive computer model that is capable of simulating the surface-water, ground-water, and stream-aquifer interactions on a continuous basis for the Rattlesnake Creek basin in south-central Kansas. The model is to be used as a tool for evaluating long-term water-management strategies....

A relatively simple ground water decision support system (DSS) was developed to assist in identifying salt-water vulnerable areas and in developing management policies to prevent salt-water intrusion in central Kansas. The DSS is based on a combination of numerical modeling sensitivity analyses, multiple regression analyses, and classification proc...

The Great Bend Prairie freshwater alluvial aquifer in south-central Kansas overlies a bedrock brine aquifer of Permian age. The continuous extraction of freshwater mainly for irrigation in this area has accelerated the upward movement of the saltwater, resulting in the deterioration of water quality. Predicting saltwater upconing is critical for ma...

The writers analyze the hydrologic budget and quantify the ground-water recharge impact of the Great Flood of 1993 on the Great Bend Prairie aquifer of south-central Kansas. During the summer of 1993, rainfall totals exceeded normal levels by 200% in the northern portion of the study area, while air temperature and evapotranspiration were below nor...

We assess the predictive accuracy of Glover's (1974) stream-aquifer analytical solutions, which are commonly used in administering water rights, and evaluate the impact of the assumed idealizations on administrative and management decisions. To achieve these objectives, we evaluate the predictive capabilities of the Glover stream-aquifer depletion...

We address the problem of declining streamflows in interconnected stream-aquifer systems and explore possible management options to address the problem for two areas of central Kansas: the Arkansas River valley from Kinsley to Great Bend and the lower Rattlesnake Creek Quivira National Wildlife Refuge area. The approach we followed implements, cali...

The results of a 6 year recharge study in the Great Bend Prairie of central Kansas are statistically analyzed to regionalize the limited number of site-specific but year-round measurements. Emphasis is placed on easily measured parameters and field-measured data. The results of the statistical analysis reveal that a typical recharge event in centra...

The hypothesis is explored that groundwater-level rises in the Great Bend Prairie aquifer of Kansas are caused not only by water percolating downward through the soil but also by pressure pulses from stream flooding that propagate in a translatory motion through numerous high hydraulic diffusivity buried channels crossing the Great Bend Prairie aqu...

A relatively simple and practical approach for calculating groundwater recharge in semiarid plain environments with a relatively shallow water table, such as the Kansas Prairies, is outlined. Major uncertainties in the Darcian, water balance, and groundwater fluctuation analysis approaches are outlined, and a combination methodology for reducing so...

Two flooding experiments were conducted at two sites with different soils to study the transport and fate of the commonly used herbicide atrazine and inorganic chemicals in the Great Bend Prairie croplands of south-central Kansas. The instantaneous profile method supplemented by the use of an organic (atrazine) and an inorganic (bromide) tracer che...

During the last several years, streamflows of a number of Kansas streams have been reduced as a result of groundwater declines. In order to better understand and quantify stream-aquifer interrelationships, an eight-day comprehensive stream-aquifer pumping test, followed by recovery monitoring, was conducted along the Arkansas River near Great Bend,...

A detailed but simple hydrologic budget for the entire Rattlesnake Creek basin (3,768 km2) in south-central Kansas was developed. With this budget, using minimal daily-weather input data and the soil-plant-water system-analysis methodology, we were able to characterize the spatial distribution of the hydrologic components of the water balance withi...

Seismic reflection surveys were used to follow the drawdown in a shallow aquifer during a pumping test. Using severe analog low-cut filters and 1/4-m geophone spacings, 335 Hz reflections were obtained from the top of the saturated zone 2.7 m deep. The reflections moved down in time as the saturated zone dropped in response to pumping. The dominant...

The amounts and time distribution of groundwater recharge from precipitation over an approximately 19-month period were investigated at two instrumented sites in south-central Kansas. Precipitation and evapotranspiration sequences, soil-moisture profiles and storage changes, water fluxes in the unsaturated zone and hydraulic gradients in the satura...

This paper numerically demonstrates and quantifies the importance of capillary-fringe and variable specific yield phenomena in ground-water recharge estimations. A one-dimensional numerical experiment consisting of a soil either with a capillary fringe or without it was set up using a finite-element code. A prescribed infiltrating flux was superimp...

To quantify and model the natural groundwater-recharge process, two sites in south-central Kansas, U.S.A., were instrumented with various modern sensors and data microloggers. The atmospheric-boundary layer and the unsaturated and saturated soil zones were monitored as a unified regime. Data from the various sensors were collected using micrologger...

Aquifers found in glacial buried valleys are a major source of good-quality ground water in northeastern Kansas. The extent and character of many of these deposits are not precisely known, so a detailed study of the buried valleys was undertaken. Test drilling, Landsat imagery, shallow-earth temperature measurements, seismic refraction, surface ele...

The use of ground water increased rapidly in the Pawnee Valley, Kansas, during the last two decades, causing ground-water levels to decline and streamflow to diminish. Therefore, this study was undertaken to evaluate the impact of present and future ground-water withdrawals in the region. This report documents the depleting water resource of the ar...