James K. Koelliker

Integrated numerical modeling for basin-wide water management: The case of the Rattlesnake Creek basin in south-central Kansas

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. The agriculturally-based watershed model SWAT and the ground-water model MODFLOW with stream-aquifer interaction routines, suitably modified, were linked into a comprehensive basin model known as SWATMOD. The hydrologic response unit concept was implemented to overcome the quasi-lumped nature of SWAT and represent the heterogeneity within each subbasin of the basin model. A graphical user-interface and a decision support system were also developed to evaluate scenarios involving manipulation of water rights and agricultural land uses on stream-aquifer system response. An extensive sensitivity analysis on model parameters was conducted, and model limitations and parameter uncertainties were emphasized. A combination of trial-and-error and inverse modeling techniques were employed to calibrate the model against multiple calibration targets of measured ground-water levels, streamflows, and reported irrigation amounts. The split-sample technique was employed for corroborating the calibrated model. The model was run for a 40 y historical simulation period, and a 40 y prediction period. A number of hypothetical management scenarios involving reductions and variations in withdrawal rates and patterns were simulated. The SWATMOD model was developed as a hydrologically rational low-flow model for analyzing, in a user-friendly manner, the conditions in the basin when there is a shortage of water.

Development and application of a comprehensive simulation model to evaluate impacts of watershed structures and irrigation water use on streamflow and groundwater: the case of Wet Walnut Creek Watershed, Kansas, USA

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, which in turn affect availability of water for the Cheyenne Bottoms Wildlife Refuge Management area. The surface-water flow model, POTYLDR, and the groundwater flow model, MODFLOW, were combined into an integrated, watershed-scale, continuous simulation model. Major revisions and enhancements were made to the POTYLDR and MODFLOW models for simulating the detailed hydrologic budget for the Wet Walnut Creek Watershed. The computer simulation model was calibrated and verified using historical streamflow records (at Albert and Nekoma gaging stations), reported irrigation water use, observed water-level elevations in watershed structure pools, and groundwater levels in the alluvial aquifer system. To assess the impact of watershed structures and irrigation water use on streamflow and groundwater levels, a number of hypothetical management scenarios were simulated under various operational criteria for watershed structures and different annual limits on water use for irrigation. A standard “base case” was defined to allow comparative analysis of the results of different scenarios. The simulated streamflows showed that watershed structures decrease both streamflows and groundwater levels in the watershed. The amount of water used for irrigation has a substantial effect on the total simulated streamflow and groundwater levels, indicating that irrigation is a major budget item for managing water resources in the watershed. q 2000 Elsevier Science B.V. All rights reserved.

An integrated approach for water quality assessment of a Kansas watershed

An integrated modeling process was used to estimate the nutrient loadings of different sub-watersheds of the Cheney Reservoir watershed, Kansas, USA. The Agricultural Nonpoint Source Pollution (AGNPS)-ARC INFO interface was used to extract input parameters from various Geographic Information System (GIS) layers, including a landcover layer prepared from Landsat TM image, for the AGNPS model during selected storm events. The curve numbers (CNs) were adjusted depending on the antecedent moisture condition (AMC) of the sub-watershed before each storm. The storm energy intensity (EI) values were computed using a probability method from a rainfall-EI relationship for the location of the study area. Several sensitive parameters of the AGNPS model were then calibrated to match the model-estimated total nitrogen (total-N) and total phosphorous (total-P) with the measured data on a sub-watershed basis during various runoff events. This process was validated by running the calibrated AGNPS model on each sub-watershed of the Cheney Reservoir watershed. This integrated modeling process was found to be effective for smaller watersheds that had adequate rainfall data.

Watershed-scale AMC selection for hydrologic modeling

The Natural Resources Conservation Service curve–number (CN) method commonly uses three discrete levels (1, 2, and 3) of antecedent moisture condition (AMC) to describe soil moisture at the time of a runoff event. However, this may not adequately represent soil water conditions for watershed modeling purposes. The objectives of this study were to evaluate the use of individual–event watershed–scale AMC values to adjust field–scale CN, and to assess which hydrologic parameters would provide the best estimate of individual–event AMC. Landsat Thematic Mapper images from 1997 and 1998 were used to obtain 10 landcover classes for Red Rock Creek watershed, Kansas. The canopy growth of crops was used to provide temporal adjustment of CNs in the watershed. Stream–flow data for 1997–1999 was collected from a U.S. Geological Survey gaging station near the watershed outlet, and base flow was separated to obtain surface–runoff amounts. Watershed–average AMC factors were estimated from measured rainfall and surface runoff amounts for each of 23 events and used to adjust CNs in the AGNPS watershed model. For individual runoff events, calibration was achieved with AMCs that averaged 1.5 and ranged from 0.9 to 2.4. Therefore, an AMC of 2, as used in many hydrologic models, would overestimate the surface runoff amounts in this sub–humid Kansas watershed. Generally, AMC increased with 5-day antecedent rainfall above 5 mm. Soil moisture and 5–day antecedent rain were found to be significantly correlated to AMC.

Applicability of linearized Boussinesq equation for modeling bank storage under uncertain aquifer parameters

Abstract Boussinesqs equation is frequently employed to study the influence of flood-stage hydrographs in streams on bank storage effects. This equation is nonlinear and no analytical solutions are available for arbitrarily shaped stage hydrographs. Analytical solutions are presented for the linearized form of the equation, and expressions for the flow rate from the stream to the aquifer are developed. Results indicate that these analytical solutions may not be very accurate (as much as 10% error) when compared with numerical solution of the nonlinear equation. These deterministic analytical solutions lead to analytical expressions for the mean and variance of flux rates when the hydraulic properties of the aquifer are treated as random quantities. Monte-Carlo simulation results show that linearized analytical solutions are potentially useful for predicting mean flux rates when aquifer properties exhibit a large degree of variability.

Linearised Boussinesq equation for modelling bank storage – a correction

In a recent paper, Govindaraju and Koelliker used the Boussinesq equation to describe the horizontal one-dimensional flow of water into an unconfined aquifer from a channel. An improved analytical approach is suggested both for constant and time dependent boundary conditions using the linearised Boussinesq equation. The results are compared with those of Govindaraju and Koelliker and the numerical solution of the Boussinesq equation. The new analytical approach yields better results, especially for positive fluxes from stream to aquifer, and is as easy to apply as the method of Govindaraju and Koelliker. When the flux is negative more theoretical studies are needed.

Effect of Cell Size on AGNPS Predictions

This paper presents a study of Agricultural NonPoint Source Pollution (AGNPS) model using different cell sizes of 4-ha, 16-ha, 65-ha, and 260-ha with geomorphic calculation to study the effects of cell sizes on the predicted results. Red Rock Creek watershed of Kansas has been selected for running different sized storms of 0.05-, 0.5-, 1-, 2-, 20-, and 200-year storms. This study incorporated remotely sensed Landsat TM image to obtain landcover and different C-factors based on rangeland quantity and residue cover on cropland. AGNPS model input parameters were extracted from different GIS layers using the AGNPS-ARC/INFO interface. Five cells of 260-ha sizes were randomly selected for comparing the different average AGNPS parameters computed with each cell size. The peak flow rate, sediment yield, and nutrients outputs observed at the outlet of the watershed were found to decrease with cell size from 4-ha to 16-ha and then increase with the cell size. The flow path length computed by AGNPS decreased with the cell size.

A hydrologic balance approach to saline seep remediation design.

Concern about saline seeps is increasing in the dryland production regions of Kansas and the North American Great Plains. To reclaim salt-affected seep areas, site hydrologic factors must be modified to reduce seep recharge. A simple method is needed to help design effective remediation treatments. A hydrologic balance model, POTYLDR (Potential Yield Model, Revised), was modified and used to estimate the water balance in a saline seep recharge area and to estimate the effectiveness of various acreages of alfalfa treatments in reducing seep recharge. This model uses readily available data, such as daily rainfall and temperature, NRCS runoff curve numbers, NRCS soil irrigation classes, Penman evapotranspiration parameters and Blaney-Criddle crop coefficients, to determine runoff, evapotranspiration, soil moisture, and percolation from the root zone. According to the assumed seep mechanism, deep percolation from the local recharge area was used to estimate seep recharge. Various percentages of the seep recharge area were shifted from the current wheat cropping to alfalfa to determine the reductions in total recharge and number of months contributing to recharge. A 50% reduction in total recharge required 14 to 32% alfalfa acreage depending upon site-specific factors of five targeted fields. A given alfalfa acreage reduced total recharge volume more effectively than it reduced the number of months contributing to recharge. The major limitation in application of these results is selection of the percentage seepage reduction needed to provide seep control. The modeling approach provides an important indication of a system’s responsiveness to changes in vegetation and quantifies this response in a way that is useful for designing bioremediation treatments that require control of seepage or shallow groundwater recharge.

KANSAS WATER-CEMENT RATIO METER: PRELIMINARY RESULTS

The water-cement ratio of fresh concrete is recognized as the one factor that affects the strength and durability of an adequately compacted concrete mix. Although water-cement ratio is the predominant factor affecting strength of hardened concrete, currently no widely used, reliable method is available for measuring water-cement ratio in the field. A prototype device has been developed to measure the water-cement ratio of a plastic concrete mix. The method is based on the measurement of turbidity of water-cement slurry separated out of a concrete mixture by pressure sieving. Consistent results were obtained for air-entrained and non-air-entrained concrete. Statistical analyses of the test results have shown that this meter can measure the water-cement ratio of fresh concrete with an accuracy of ±0.01 on the water-cement ratio scale for a single test at a 90 percent confidence interval. The equipment will cost less than

Modeling Alternative Treatments Systems for CAFOs in Kansas

10,000. If the method works as well in the field as it does in the laboratory, accura...