Des Moines River Research Articles

Enterococcus in surface waters from the Des Moines River (Iowa) watershed: location, persistence and vancomycin resistance

The object of this study was to quantify vancomycin-resistant enterococci in surface water from Central Iowa obtained from April 2007 to August 2007. Water from established sampling sites in four watersheds was plated on bile-esculin agar. Presumptively identified enterococci were categorized as “above the level of concern” if the sample contained ≥107 CFU per 100 ml. Confirmation of isolates as enterococci was based on growth at elevated temperature in high salt and on Enterococcus agar. Isolates that grew on 6 μg/ml vancomycin agar were deemed resistant. PCR analysis of resistant strains characterized vancomycin resistance genes. 77.2% of surface water samples from Central Iowa contained enterococci. Among enterococcal isolates, 10.4% grew on media containing 6 μg/ml vancomycin. PCR analysis of resistance genes showed a preponderance of VanC2/C3 in the area studied and VanB was not detected. Vancomycin-resistant Enterococcus is present in Central Iowa surface waters but resistance rarely involved VanA genotypes. Nevertheless, the potential for community-acquired infections remains a risk.

A Modeling Framework for the Design of Collector Wells

We present results of a design study performed for the Saylorville Wellfield in Iowa, which is owned and operated by the Des Moines Water Works. The purpose of this study was to estimate wellfield capacity and provide a preliminary design for two radial collector wells to be constructed in the outwash aquifer along the Des Moines River near Saylorville, Iowa. After a field investigation to characterize the aquifer, regional two-dimensional and local three-dimensional, steady-state groundwater flow modeling was performed to locate and design the wells. This modeling was the foundation for design recommendations based on the relative performance of 12 collector well designs with varying lateral numbers, elevations, screen lengths, and orientations. For each site, alternate designs were evaluated based on model estimates of the capacity, the percent of surface water captured, and the production per unit length of screen. Many of our results are consistent with current design practices based on experience and intuition, but our methods allow for a quantitative approach for comparing alternate designs. Although the results are site-specific, the framework for evaluating the hydraulic design of the Saylorville radial collector wells is broadly applicable and could be used at other riverbank filtration sites. In addition, many of the conclusions from this design study may apply at other sites where construction of radial collector wells is being considered.

History of Ecological Sciences, Part 38B: Naturalists Explore North America, 1838–1850s

History of Ecological Sciences, Part 38B: Naturalists Explore North America, 1838–1850s

Risk analysis of seasonal stream water quality management

Seasonal discharge programs, which take advantage of temporal variation of stream assimilative capacity, are cost effective. However, these seasonal discharge control programs should not increase the risk of water quality violations. A method is presented to estimate the allowable pollutant loads under both seasonal and non-seasonal discharge control programs for a single discharger that maintains the same level of risk of water quality violation. An enhanced in-stream water quality model QUAL2E-UNCAS was applied to a 39-km river reach of the Des Moines River below Des Moines Sewage Treatment Plant (DMSTP) in Iowa. The model was calibrated for dissolved oxygen (DO), biological oxygen demand (BOD), and ammonia as nitrogen with standard errors of 10, 17, and 23% by comparing with the observed water quality data. Monte-Carlo simulation technique was then implemented for seasonal and non-seasonal discharge program to assess the water quality violation risk and the allowable pollutant load. The results indicated that the four-seasonal program offers about 136% increase in BOD loading and 61% increase in ammonia loading when compared with the non-seasonal program without any increase in the violation probabilities, whereas the two-seasonal program only offers 13% decrease in BOD loading and 56% increase in ammonia loading. It is found that the multi-discharge program was beneficial for both water quality indicators, and thus provides a way of reducing the overall cost of waste treatment.

Modeling Nitrate-Nitrogen Load Reduction Strategies for the Des Moines River, Iowa Using SWAT

The Des Moines River that drains a watershed of 16,175 km(2) in portions of Iowa and Minnesota is impaired for nitrate-nitrogen (nitrate) due to concentrations that exceed regulatory limits for public water supplies. The Soil Water Assessment Tool (SWAT) model was used to model streamflow and nitrate loads and evaluate a suite of basin-wide changes and targeting configurations to potentially reduce nitrate loads in the river. The SWAT model comprised 173 subbasins and 2,516 hydrologic response units and included point and nonpoint nitrogen sources. The model was calibrated for an 11-year period and three basin-wide and four targeting strategies were evaluated. Results indicated that nonpoint sources accounted for 95% of the total nitrate export. Reduction in fertilizer applications from 170 to 50 kg/ha achieved the 38% reduction in nitrate loads, exceeding the 34% reduction required. In terms of targeting, the most efficient load reductions occurred when fertilizer applications were reduced in subbasins nearest the watershed outlet. The greatest load reduction for the area of land treated was associated with reducing loads from 55 subbasins with the highest nitrate loads, achieving a 14% reduction in nitrate loads achieved by reducing applications on 30% of the land area. SWAT model results provide much needed guidance on how to begin implementing load reduction strategies most efficiently in the Des Moines River watershed.

Time-series modeling of reservoir effects on river nitrate concentrations

Saylorville Reservoir is a 24.1 km 2 impoundment of the Des Moines River located approximately 10 km north of the City of Des Moines, Iowa, USA. Surface water from the Des Moines River used for drinking water supply is impaired for nitrate–nitrogen. Monthly mean nitrate concentration data collected upstream and downstream of the reservoir for a 30-year period (1977–2006) were selected for time-series analysis. Our objectives were to (1) develop a model describing nitrate concentrations downstream of the reservoir as a function of the concentrations entering the reservoir and (2) use the model to provide a 1-month ahead forecast for downstream water quality. Results indicated that downstream nitrate can be effectively modeled using a transfer function approach that utilized inflow concentrations during the current and previous month as input variables. Inflow concentrations were modeled using an AR(20) model, with the higher order model consistent with temporal correlation noted by others. The transfer function model suggested that the reservoir is reducing nitrate concentrations by 22 ± 6%, a reduction that greatly exceeds previous estimates. Monthly nitrate forecasted with the model were nearly all within a 95% prediction interval of their actual measured values and did not appear greatly affected by flow variations.

Copula‐based flood frequency (COFF) analysis at the confluences of river systems

AbstractMany civil infrastructures are located near the confluence of two streams, where they may be subject to inundation by high flows from either stream or both. These infrastructures, such as highway bridges, are designed to meet specified performance objectives for floods of a specified return period (e.g. the 100 year flood). Because the flooding of structures on one stream can be affected by high flows on the other stream, it is important to know the relationship between the coincident exceedence probabilities on the confluent stream pair in many hydrological engineering practices. Currently, the National Flood Frequency Program (NFF), which was developed by the US Geological Survey (USGS) and based on regional analysis, is probably the most popular model for ungauged site flood estimation and could be employed to estimate flood probabilities at the confluence points. The need for improved infrastructure design at such sites has motivated a renewed interest in the development of more rigorous joint probability distributions of the coincident flows. To accomplish this, a practical procedure is needed to determine the crucial bivariate distributions of design flows at stream confluences. In the past, the copula method provided a way to construct multivariate distribution functions. This paper aims to develop the Copula‐based Flood Frequency (COFF) method at the confluence points with any type of marginal distributions via the use of Archimedean copulas and dependent parameters. The practical implementation was assessed and tested against the standard NFF approach by a case study in Iowa's Des Moines River. Monte Carlo simulations proved the success of the generalized copula‐based joint distribution algorithm. Copyright © 2009 John Wiley & Sons, Ltd.

Indice fisicoquímico de la calidad de agua para el manejo de lagunas tropicales de inundación

We propose ICA-L, a wetland physicochemical water quality index (WWQI), to be used as a management tool for seasonal-flooding lagoons in Palo Verde National Park, Guanacaste, Costa Rica. The goal is to preserve their natural role for native plants as well as migrants and local animal species. The index was developed in four steps: parameter selection, assignment of parameter weight, transformation of data to their corresponding sub indices and selection of an appropriate aggregation function. In this process, the following criteria were used as a reference: WQI from the National Sanitation Foundation, WQI for the Des Moines River, Escribano and De Frutos WQI, the international legislation on maximum acceptable concentration for different water quality variables, and the authors' personal criteria. The index includes the following parameters: dissolved oxygen percent saturation, pH, nitrate concentration, total phosphorus concentration, chemical oxygen demand, concentration of suspended solids, electrical conductivity and temperature. The index sets itself to zero if the concentration of some toxic substance exceeds the maximum allowed limit. The adjustment values were based on "weights" defined in the National Sanitation Foundation Water quality Index (ICA-NSF). In this study, the weight of fecal coliforms count was excluded, the values of turbidity and the one for total solids were integrated into one (suspended solids) and a factor of 0.08 was assigned to the conductivity parameter. The sub indices associated to suspended solids were obtained from the quality of Kahler-Royer variation graph; the values for pH and the nitrate concentration from the graphs constructed for ICA-NSF. The percentage of dissolved oxygen saturation, in sites like irrigation channels, was evaluated directly from the quality variation graph constructed for ICA-NSF, whereas the same parameter for the flooding lagoons required an adjustment based on the optimal value for similar non contaminated ecosystems. The conductivity was evaluated from adjustments in the qualification functions commented by Escribano & De Frutos. Chemical oxygen demand, total phosphorus and temperature, were qualified based on the functions developed for the ICA-L.

Evaluation of bias-correction methods for ensemble streamflow volume forecasts

Abstract. Ensemble prediction systems are used operationally to make probabilistic streamflow forecasts for seasonal time scales. However, hydrological models used for ensemble streamflow prediction often have simulation biases that degrade forecast quality and limit the operational usefulness of the forecasts. This study evaluates three bias-correction methods for ensemble streamflow volume forecasts. All three adjust the ensemble traces using a transformation derived with simulated and observed flows from a historical simulation. The quality of probabilistic forecasts issued when using the three bias-correction methods is evaluated using a distributions-oriented verification approach. Comparisons are made of retrospective forecasts of monthly flow volumes for a north-central United States basin (Des Moines River, Iowa), issued sequentially for each month over a 48-year record. The results show that all three bias-correction methods significantly improve forecast quality by eliminating unconditional biases and enhancing the potential skill. Still, subtle differences in the attributes of the bias-corrected forecasts have important implications for their use in operational decision-making. Diagnostic verification distinguishes these attributes in a context meaningful for decision-making, providing criteria to choose among bias-correction methods with comparable skill.

Distributions-Oriented Verification of Ensemble Streamflow Predictions

Abstract Ensemble streamflow prediction systems produce forecasts in the form of a conditional probability distribution for a continuous forecast variable. A distributions-oriented approach is presented for verification of these probability distribution forecasts. First, a flow threshold is used to transform the ensemble forecast into a probability forecast for a dichotomous event. The event is said to occur if the observed flow is less than or equal to the threshold; the probability forecast is the probability that the event occurs. The distributions-oriented approach, which has been developed for meteorological forecast verification, is then applied to estimate forecast quality measures for a verification dataset. The results are summarized for thresholds chosen to cover the range of possible flow outcomes. To aid in the comparison for different thresholds, relative measures are used to assess forecast quality. An application with experimental forecasts for the Des Moines River basin illustrates the app...

Revisiting nitrate concentrations in the Des Moines River: 1945 and 1976-2001.

Recent compilations of historical and contemporary riverine nitrate (NO3) concentrations indicate that concentrations in many rivers in the north-central USA increased during the second half of the 20th century. The Des Moines River near Des Moines, Iowa, however, was reported to have had similar NO3 concentrations in 1945 and the 1980s, in spite of substantially greater N input to the watershed during the latter period. The objective of this study was to reconsider the comparison of historical and contemporary NO3 concentrations in the Des Moines River near Des Moines in light of the following: (i) possible errors in the historical data used, (ii) variations in methods of sample collection, (iii) variations in location of sampling, and (iv) additional data collected since 1990. We discovered that an earlier study had compared the flow-weighted average concentration in 1945 to arithmetic annual average concentrations in the 1980s. The intertemporal comparison also appeared to be influenced by differences in sample collection methods and locations used at different times. Depending on the model used and the estimated effects of composite sample collection, the 1945 arithmetic average NO3 concentration was between 44 and 57% of the expected mean value at a similar water yield during 1976-2001. The flow-weighted average NO3 concentration for 1945 was between 54 and 73% of the expected mean value at a similar water yield during 1976-2001. The difference between NO3 concentrations in 1945 and the contemporary period are larger than previously reported for the Des Moines River.

THE PRONUNCIATION OFMISSOURI: VARIATION AND CHANGE IN AMERICAN ENGLISH

�� Why do some people say Missour-ee and others say Missour-uh? Which one is “correct”? The spellings in early documents and comments made in print since the late 1600s indicate the existence of considerable variation in the pronunciations of all three vowels and the medial consonant in the word Missouri. An individual may attempt to account for a particular pronunciation on the basis of spelling or on “how the Indians said the word.” In answering the opening questions, this article will take a brief look at “what the Indians said” to early explorers and how nineteenth-century Missouri Indians said the word and then examine evidence from several sources, the most important being the Linguistic Atlas Projects. We know that the Siouan tribe living near the Missouri River did not use the word Missouri before they had borrowed it from the French voyageurs, because a neighboring tribe from a different language family is the source of the name. When Jacques Marquette (1637–75) and Louis Jolliet (1645– 1700) were exploring the Mississippi Valley in 1673, they visited the Peorias (a group within the Illinois branch of the Algonquian Indians) near the mouth of the Des Moines River and asked them “to give us all the information that they had about the sea [Bassin de la Floride, i.e., Gulf of Mexico]

Linear Programming for Flood Control in the Iowa and Des Moines Rivers

This study addresses questions related to flood-control operating procedures followed by the U.S. Army Corps of Engineers, Rock Island District. Application is presented of a mixed integer linear programming model for a reservoir system analysis of three U.S. Army Corps of Engineers' projects on the Iowa and Des Moines rivers. A strategy for evaluating the value of coordinated reservoir operations is developed. Results of this study suggest that operating Coralville Reservoir, on the Iowa River, for flood control on the Mississippi River does not provide appreciable benefits and, therefore, an operation plan coordinating releases from Coralville Reservoir with the two reservoirs on the Des Moines River may be unnecessary. Damage-minimizing results were obtained by operating the three reservoirs independently for 8 of the 10 largest flood events on record. Also, a review of the operating procedures for the flood of 1993 illustrates how much damage could have been reduced if inflows could be predicted month...

Advanced hydrologic prediction system

As our Nation's population and infrastructure grow, natural disasters are becoming a greater threat to our society's stability. In an average year, inland flooding claims 133 lives and resulting property losses exceed $4.0 billion. Last year, 1997, these losses totaled $8.7 billion. Because of this blossoming threat, the National Weather Service (NWS) has requested funding within its 2000 budget to begin national implementation of the Advanced Hydrologic Prediction System (AHPS). With this system in place the NWS will be able to utilize precipitation and climate predictions to provide extended probabilistic river forecasts for risk‐based decisions. In addition to flood and drought mitigation benefits, extended river forecasts will benefit water resource managers in decision making regarding water supply, agriculture, navigation, hydropower, and ecosystems. It's estimated that AHPS, if implemented nationwide, would save lives and provide $677 million per year in economic benefits. AHPS is used currently on the Des Moines River basin in Iowa and will be implemented soon on the Minnesota River basin in Minnesota. Experience gained from user interaction is leading to refined and enhanced product formats and displays. This discussion will elaborate on the technical requirements associated with AHPS implementation, its enhanced products and informational displays, and further refinements based on customer feedback.

Water quality modeling in the watershed-based approach for waste load allocations

The conventional method for waste load allocations (WLA) employs spatial-differentiation, considering individual point sources, and temporal-integration, using a constant flow, typically 7Q10 low flow. This paper presents a watershed-based seasonal management approach, in which non-point source as well as point sources are incorporated, seasonal design flows are used for water quality analysis, and WLA are performend in a watershed scale. The strategy for surface water quality modeling in the watershed-based approach is described. The concept of seasonal discharge management is discussed and suggested for the watershed-based approach. A case study using the method for the Des Moines River, Iowa, USA is conducted. Modeling considerations and procedure are presented. The significance of non-point source pollutant load and its impact on water quality of the river is evaluated by analyzing field data. A water quality model is selected and validated against field measurements. The model is applied to projections of future water quality situations under different watershed management and water quality control scenarios with respect to river flow and pollutant loading rate.

Water quality modeling in the watershed-based approach for waste load allocations

The conventional method for waste load allocations (WLA) employs spatial-differentiation, considering individual point sources, and temporal-integration, using a constant flow, typically 7Q10 low flow. This paper presents a watershed-based seasonal management approach, in which non-point source as well as point sources are incorporated, seasonal design flows are used for water quality analysis, and WLA are performend in a watershed scale. The strategy for surface water quality modeling in the watershed-based approach is described. The concept of seasonal discharge management is discussed and suggested for the watershed-based approach. A case study using the method for the Des Moines River, Iowa, USA is conducted. Modeling considerations and procedure are presented. The significance of non-point source pollutant load and its impact on water quality of the river is evaluated by analyzing field data. A water quality model is selected and validated against field measurements. The model is applied to projections of future water quality situations under different watershed management and water quality control scenarios with respect to river flow and pollutant loading rate.

Late Quaternary Upper Mississippi River alluvial episodes and their significance to the Lower Mississippi River system

Late Quaternary Upper Mississippi River alluvial episodes and their significance to the Lower Mississippi River system

Hydrological applications of satellite data: 1. Rainfall estimation

In this study we investigate the ability of satellite visible and infrared data to produce reliable rainfall amount estimates that could be used by hydrological models to predict streamflow for large basins. Rainfall estimates are obtained by (1) classification of clouds to raining and nonraining clouds and (2) applying a multivariate statistical model between rainfall and indices derived from the satellite observations. Satellite data corresponding to 180 randomly selected days in the period May‐September 1982–1988 are used in this study that focuses on the estimation of daily rainfall. The Des Moines River basin in the midwestern United States is the application area. The correlation coefficient between model‐predicted and rain gauge‐observed mean areal precipitation over areas of order 10,000 km2 is found to be about 0.85. In an example application the satellite rainfall estimates are used to force the operational National Weather Service hydrologic forecast model for a subbasin of the Des Moines River basin. The model has been calibrated with rain gauge data. The results show that differences between rain gauge and satellite rainfall input generate differences in flow forecasts and upper soil water model estimates, which are a function of the antecedent soil water conditions. A companion paper [Guetter et al., this issue] quantifies the effects that the differences between rain gauge and satellite rainfall estimates have on flow and upper soil water model predictions for various spatial scales and for hydrologic models calibrated with and without satellite data.

Des Moines River Nitrate in Relation to Watershed Agricultural Practices: 1945 Versus 1980s

AbstractConcern for nitrate (NO3‐N) contamination of surface waters in Iowa has brought much speculation with regard to the source of NO3‐N. It is frequently assumed that the large percentage increase in fertilizer N use over the last 50 yr is the primary cause of high concentrations of NO3‐N in surface waters of central Iowa. We performed an analysis of data relating flow and NO3‐N concentration for the Des Moines River to identify the effect of agricultural practices on NO3‐N in the river. Annual and weekly stream flow values for the 1980‐1990 period at a site just below the city of Des Moines were positively related to the NO3‐N concentration in the river water for the 11‐yr period (r2 = 0.60, P < 0.01). From 1980 to 1991 the average annual NO3‐N concentration ranged from 2.0 mg L−1 in the low flow year of 1989 to 9.1 mg L−1 in 1982. Over the 11 yr, the river averaged 5.6 mg L−1 NO3‐N and had an average flow of 733 580 m3 h−1. In 1945, the average flow was 723 710 m3 h−1 and NO3‐N concentrations were 5.0 mg L−1. These values were similar to the 11‐yr average data obtained 35 to 45 yr later. We infer from the data that the intensive agricultural activities in 1945 and 1980 to 1990 are the major source of the NO3‐N to the river rather than solely N fertilizer. Changes in land management, cropping patterns, and land use are therefore required to markedly lower the NO3‐N levels of surface water in this basin.

Local Factors in Changing Land-Tenure Patterns

An examination of changing patterns of land tenure in a four- section area of Lake Prairie Township, south-central Iowa, reveals that land prices followed similar trends at all scales and were largely controlled by macroscale forces. Discontinuity existed between regional and local trends in farm-tenure structure. Microscale phenomena like age structure, ethnicity, and local values were the important determinants of landownership change at the local level. COMMUNITYWIDE social patterns in the rural United States affect farm systems. These patterns are especially evident among ethnically and religiously homogeneous groups who reside in agricultural regions of the Midwest. These localized value systems influence capitalization of farm enterprises, the commercial character of a farm, and farmers' risk-reduction strategies. More importantly, these value systems have led to communitywide patterns of strategies for intergenerational land transfers, the effectiveness of which is the sustainability of the farm unit. Inasmuch as landuse is tied to ownership, the continued re-creation of the farm enterprise may also be related. The goal of this article is to expand the scope of previous studies by demonstrating a methodology for analyzing local tenure patterns in the context of their interaction with larger forces. Changes in land tenure are examined for four sections or four square miles of land in Lake Prairie Township, south-central Iowa, from settlement in the 1840s to the early 1980s. These sections, part of an area settled by Dutch immigrants, contain a variety of land classes and are bounded on the northeast by a main highway and railroad and on the southwest by Red Rock reservoir on the Des Moines River (Fig. 1). County-deed records, which contain a century and a half of data on all land transactions in the four sections, form the basis of the study. The study draws on information regarding land prices; categories of transactions, such as free exchange, intrafamilial sale, inheritance, or fore- closure; types of buyers or sellers, such as private, corporate, or governmental; residence of buyers and sellers; and relationships among buyers and sellers. These data were supplemented by cemetery records and by family and oral histories. Changes in these aspects of land tenure were compared with county and regional data to analyze the interactions between the specific and the general and to assess which factors were tied to externally driven, macrosocial phenomena and which were connected with locally determined, microsocial