An analysis of the Iowa City Ralston Creek hourly precipitation record is made prior to construction of data generation models to be used in an urbanization-flooding hazard study. The historical record of hourly precipitation has been constructed from a high density recording gage network within the watershed, with an unbroken length of 33 years (50 years with some discontinuities). A stochastic precipitation model is proposed on phenomenological terms for the time occurrence of storm events. Wet time intervals are scheduled using models for inter-arrival times. Traditional computation difficulties are circumvented in modeling certain time-related persistence effects through the use of independent random variables. The models are presented, described, fit to the data, discussed, and future work is outlined.

The U.S.D.A. SCS (now the NRCS) Curve Number method has been in continuous use for about 50 years. As originally developed, the method yields a direct runoff depth from the accumulated 24 hour rainfall depth as function of the curve number CN. The method has since been extended to hydrograph generation and is found in commonly used hydrologic models applied to urban drainage design (e.g., WinTR55, SWMM and HEC-HMS). A number of recently published studies, including Curve Number Hydrology - State of the Practice, by the ASCE/EWRI Curve Number Hydrology Task Committee, have warned that it is inappropriate to use the method to generate runoff hydrographs, yet the practice continues with little awareness of this limitation by most users. A common misconception is that the CN method is an infiltration model, which can lead to significant errors in peak discharge predictions. CN values can be converted into equivalent physically based infiltration model parameters used in the Green-Ampt method in SWMM (or HEC-HMS), or in the infiltration component used in the PERLND module of EPA's HSPF model, each of which can produce a more acceptable hydrograph that matches CN method direct runoff depth.

The watershed characterization and modeling system (WCMS) was developed to support decision making and the management of water resources at a statewide level in West Virginia. Specific hydrological analysis functions were combined within a customized GIS interface to provide decision support capabilities to both technical and non-technical users. Components of the current system include: an overland flow path model that indicates optimum water quality sampling locations, flow estimation for all streams in an identified area, an instream water quality and loading model for pollutant levels, and a ranking model to prioritize treatment alternatives based on user defined criteria and preferences. The primary goals of this system are to provide consistent technical information related to natural watershed processes and to predict the impacts of alternative management scenarios for decision makers. WCMS is currently used by the West Virginia Department of Environmental Protection (WVDEP) to guide policy development and management decisions that address watershed and water quality issues throughout the state.

The West Virginia Department of Environmental Protection (WVDEP) and the U.S. Office of Surface Mining, Reclamation and Enforcement (OSMRE) have identified a need for a groundwater modeling capability within the existing WCMS (Watershed Characterization and Modeling System). WCMS is a combination of software and data developed by the Natural Resource Analysis Center (NRAC) at West Virginia University (WVU). The software component of WCMS adds GIS tools to ESRI ArcGIS 9.x software to support the analysis of water quantity and quality issues throughout the state of West Virginia at a watershed scale consistent with the 1:24,000 scale NHD stream segmentation. WCMS is currently used by permit writers in the WVDEP Divisions of Water and Waste Management (DWWM) and Mining and Reclamation (DMR). The EPA HSPF (Hydrologic Simulation Program - Fortran) watershed model, a recent tool addition to WCMS, is accepted by state and federal agencies as one of the standards of surface water hydrology and water quality modeling. The WCMS- HSPF groundwater model component currently under development supports the use of MODFLOW as an option where adequate data are available and the additional analysis time can be justified. Although USGS MODFLOW is a universally accepted standard for groundwater modeling, MODFLOW applications are to be imbedded within a proposed spatially larger, more approximate WCMS routine, coined as the "Regional Groundwater Recharge Model" (RGRM), which effectively replaces the existing groundwater component within WCMS-HSPF. RGRM is to be calibrated jointly with HSPF using the recessionary portion of stream flow data, and will execute together with HSPF to close the groundwater mass balance portion of the watershed model. A new WCMS toolbar is being developed to support the addition of underground mine features and data input specific to the RGRM groundwater hydraulics.

Highway drainage channels often approach slopes of 0.5 (50%). Single layer riprap-lined channels at this slope have been constructed for highway drainage and appear to perform satisfactorily, but no quantitative information is available to guide their hydraulic design. A 1/6 scale laboratory hydraulic model, using a single layer of sized crushed limestone, was constructed to determine the relationship between depth of flow and discharge. The flow range investigated took place at depths near or below the top of the riprap, since riprap instability occurred at greater depths. Standing waves and localized hydraulic jumps dominated the surface of the flow, which held streamwise-averaged Froude numbers in a narrow range near the critical condition for those flow depths for which the channel is designed. This resulted in a simple relationship between unit discharge and depth of flow that applies to the model and prototype channels.

As defined by the Surface Mining Control and Reclamation Act (SMCRA), a Cumulative Hydrologic Impact Assessment (CHIA) is required for all proposed coal mine permits. The Natural Resource Analysis Center (NRAC) at West Virginia University, with support from the West Virginia Department of Environmental Protection (WVDEP) and the U.S. Office of Surface Mining, Reclamation and Enforcement (OSMRE), has developed a suite of tools based on ERSI ArcGIS software to assist in this process. The EPA watershed model Hydrologic Simulation Program-Fortran (HSPF) has been added to NRAC's Watershed Characterization and Modeling System (WCMS) to predict changes in water quality and quantity caused by surface mining. HSPF is a comprehensive watershed model containing over 20 parameters. A joint calibration approach was adopted using historical stream flow records from five calibration watersheds and four additional verification watersheds throughout West Virginia. This resulted in one parameter set representative of the entire coal mining region. Because of the lack of available stream flow data from active mine sites, a link between the NRCS Curve Number (CN) and HSPF parameters was developed based on an established empirical method. Segmentation of the study site watersheds is based on the 1:24,000 NHD stream maps. The area draining to each individual reach was delineated for the entire state by NRAC. A table defining the flow connectivity between each "reachshed" was also created. The input control file for HSPF is automatically created using the reachshed physical attribute and flow connectivity tables. This results in a faster, more efficient method of creating HSPF input files than traditional raster-based methods.

The suitability of applying the NRCS curve number (CN) to continuous runoff prediction is examined using a new technique of back-calculating CN values from the output of a complex nonlinear hydrolo...

This paper reports on a laboratory experiment conducted more than 30 years ago (Eli, 1974, unpublished), and recent Computational Fluid Dynamics (CFD) investigations, focusing on the properties of a plane tangential jet produced by an apparatus called a "centrifugal nozzle." The authors believe that the centrifugal nozzle has potential industrial applications in several areas related to fluid mixing and particulate matter suspension in mixing tanks. It is also believed that this experiment, or one similar, may provide data useful for benchmarking CFD models.

The West Virginia Department of Environmental Protection (WVDEP) with the cooperation of the Office of Surface Mining (OSM) in the U.S. Department of the Interior (USDOI) is supporting the development of GIS-based hydrologic modeling tools to conduct Cumulative Hydrologic Impact Assessments (CHIAs) of mining activities on watersheds within the coal regions of West Virginia. Approximately 235 watersheds have been established within the coal fields based on Trend Station water quality and flow monitoring points. Designed to develop baseline data to support the CHIA process, these Trend Station Watersheds (TSW) cover an area equal to approximately 40% of the state. The Natural Resource Analysis Center (NRAC), West Virginia University, is developing modeling tools to provide predictive capability for assessing the hydrologic and water quality impact of new mining permits on streams. This capability is being provided by a new set of GIS tools developed to supplement the basic functions of the Watershed Characterization and Modeling System (WCMS), an ArcGIS extension developed by NRAC. WCMS GIS tools have been used by WVDEP staff to analyze coal mine permit applications for a number of years. New WCMS tools create input files for the Hydrological Simulation Program - FORTRAN (HSPF) watershed model. These tools include mine site modeling capabilities that simulate NPDES outflows from both underground and surface coal mines. Each TSW is divided into subwatersheds consistent with the 1:24,000 NHD (National Hydrography Dataset) stream segments. The hydrology and landcover are modified to reflect the proposed impacts of mining based on information provided in permit applications. Surface mine discharges are modeled in a fashion consistent with the specific runoff curve numbers, limits, and discharges specified in the permit application. HSPF components are also used to model the watershed hydrology from underground mine discharges contribution consistent with NPDES permit effluent limitations and WV in-stream water quality standards. Water quality components of HSPF were modified to improve the simulation of acid mine drainage (AMD) discharges.

Spatially distributed rainfall patterns can now be detected using a variety of remote-sensing techniques ranging from weather radar to various satellite-based sensors. Conversion of the remote-sensed signal into rainfall rates, and hence into runoff for a given river basin, is a complex and difficult process using traditional approaches. Neural-network models hold the possibility of circumventing these difficulties by training the network to map rainfall patterns into various measures of runoff that may be of interest. To investigate the potential of this approach, a very simple 5 X 5 grid cell synthetic watershed is used to generate runoff from stochastically generated rainfall patterns. A backpropagation neural network is trained to predict the peak discharge and the time of peak resulting from a single rainfall pattern. Additionally, the neural network is trained to map a time series of three rainfall patterns into a continuum of discharges over future time by using a discrete Fourier series fit to the runoff hydrograph.

In this investigation the practicality of applying a backpropagation neural network to modeling watershed response characteristics is examined. Two separate tests were performed. One test involved testing the ability of a neural network to predict time to peak and peak discharge resulting from unique storms produced with spatially distributed rainfall. The other test involved training a neural network to predict volumetric discharge from a time series of rainfall.

It has been demonstrated elsewhere that the simple interaction of a two dimensional field of discrete particles traveling on a regular lattice yields large scale behavior closely approximating the continuum Navier-Stokes equations. Numerical experiments have been encouraging, yielding results that seem to represent complex flow fields accurately. Initial investigations into free surface fluid dynamics behaviour shows promise of appropriate flow field and surface wave representation. Experiments involving condensation of a dispersed gas to a free surface liquid, wave oscillations in a closed basin, and an unsteady uniform open channel flow, point out potential problems as well as opportunities.

A two-dimensional fluid continuum system can be modeled using a discrete field of particles that interact according to simple deterministic rules. The methodology is called Cellular Automata. The particles move in discrete space and time increments on a triangular lattice according to a limited number of nearest neighbor interaction rules. Interaction of the fluid particles occurs at the lattice nodes and conserves mass and momentum. The scheme can be shown to lead to the two-dimensional Navier-Stokes equations. A 150 by 300 node lattice is used to perform experiments of flow past a rectangular plate placed normal to the flow direction. The pressure distribution along the lateral boundaries is computed from change in particle momentum. A time series record of velocity at a fixed point in the wake illustrates a qualitative similarity to the unsteady flow observed during physical experiments.

Monitoring of wastewater discharge requires measurements of both quality and quantity to satisfy federal regulations. The use of 90-degree V-notch weirs to measure discharge at outfalls is common. In many instances the weirs are placed in culverts or other space-limited locations such that the traditional calibration parameter, head over the weir notch, is difficult to measure. Two other parameters can be specified, which involve measurements at the weir plate. These have the advantage of not requiring that an elevation datum be established. The first is measurement of depth of flow over the weir notch using a common meter stick. The second is the measurement of width of flow at the weir crest using a modified machinist's caliper. Both techniques yielded reliable measurements using a sample data set obtained from 12 students asked to perform the measurements. Measured discharge varied no more than ± 5% from actual at one standard deviation, and no more than ± 10% at two standard deviations. It was concluded that the two new parameters were adequate substitutes for traditional weir head measurements.

With the more recent development of high performance microcomputers, efforts have been made to adapt. Information Systems (GIS) software to microcomputers for application to a wide variety of Civil Engineering problems. Little problem has been encountered in fitting the software component of these systems, however, file handling limitations are requiring innovative changes in the way spatial data is stored and retrieved. Limited memory size and magnetic media storage have driven the development of data compression and segmentation techniques that will have beneficial effects in the development of both mainframe and microcomputer GIS.