• Simulation of groundwater conditions in the Colorado River Delta, Mexico

      Feirstein, Eden Jael; Zamora, Francisco; Vionnet, Leticia Beatriz; Maddock, Thomas, III; Department of Hydrology & Water Resources, The University of Arizona; Sonoran Institute; Facultad de Ingeniería y Ciencias Hídricas (FICH) - Universidad Nacional del Litoral (UNL) (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2008-05)
      The Colorado River Delta (CRD) is a large sedimentary complex within a tectonically active structurally controlled basin. The CRD lies across the U.S.-Mexico international boundary and is traversed by the Colorado River on is way to the Gulf of California. Multidisciplinary research addressing the impact of the hydrologic change in the CRD has been increasing since the 1980's. To help expand the base of this knowledge, a groundwater model for the CRD within Mexico was developed. A conceptual model was constructed and transformed within the Department of Defense Groundwater Modeling Software (GMS) into a numerical model using the MODFLOW 2005 code made available by the U.S. Geological Survey. Model results indicates that large scale flood events on the Colorado River act as a recharge to the aquifer and show that the relationship between groundwater withdrawals and capture are evident on an seasonal scale. The model will form the parent basis for further Delta studies using the Local Grid Refinement (LRG), a methodology inherent to MODFLOW 2005.
    • A riparian evapotranspiration package for MODFLOW-2000 and MODFLOW-2005

      Maddock, Thomas, III; Baird, Kathryn J.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2008-03)
      A new version of an evapotranspiration package for the U.S. Geological Survey's groundwater -flow model, MODFLOW, is documented. The Riparian Evapotranspiration Package (RIP-ET) provides flexibility in simulating riparian and wetland evapotranspiration (ET) not provided by the MODFLOW -2000 and MODFLOW 2005 traditional Evapotranspiration (EVT) Package, nor by the MODFLOW-2000 Segmented Function Evapotranspiration (ETS1) Package. This report describes how the package was conceptualized and provides input instructions, listings and explanations of the source code, and an example simulation. Traditional approaches to modeling ET processes assume a piecewise linear relationship between ET flux rate and hydraulic head. The RIP-ET replaces this traditional relationship with a segmented, nonlinear dimensionless curve that reflects the eco-physiology of riparian and wetland ecosystems. Evapotranspiration losses from these ecosystems are dependent not only on hydraulic head but on the plant types present. User -defined plant functional groups (PFGs) are used to elucidate the interactive processes of plant ET with groundwater conditions. Five generalized plant functional groups based on transpiration rates, plant rooting depth, and water tolerance ranges are presented: obligate wetland, shallow-rooted riparian, deep- rooted riparian, transitional riparian and bare ground /open water. Plant functional groups can be further divided into subgroups (PFSG) based on plant size, density or other user defined field. The RIP -ET allows for partial habitat coverage and mixtures of plant functional subgroups to be present in a single model cell. Habitat areas are designated by polygons. A polygon can contain a mixture of PFSGs and bare ground, and is assigned a calculated land surface elevation. This process requires a determination of fractional coverage for each of the plant functional subgroups present in a polygon to simulate the mixture of coverage types and resulting ET. The fractional cover within a cell has two components: 1) the polygonal fraction of active habitat in a cell, and 2) fraction of plant flux area in a polygon. The RIP -ET determines the ET rate for each plant functional group in a cell, the total ET in the cell, and the total ET rate over the region of simulation.
    • MR2K: A program to calculate drawdown, velocity, storage and capture response functions

      Maddock, Thomas, III; Lacher, Laurel J.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2008)
      A program, MR2K, used for calculating drawdown, velocity, storage loss, and capture response functions for multi -aquifer groundwater flow systems was developed. Capture is defined as the sum of the increase in aquifer recharge and decrease in aquifer discharge as a result of an applied stress from groundwater pumping. The capture phenomena treated are stream-aquifer leakance, reduction of evapotranspiration losses, reduction of drain flows, flows to and from prescribed head boundaries, and increases or decreases in natural recharge or discharge from head-dependent boundaries. The response functions are independent of the magnitude of the pumping stresses, and are dependent on the type of partial differential equation, boundary and initial conditions and the parameters thereof, and the spatial and temporal locations of stresses. The aquifers modeled may have irregular- shaped boundaries and nonhomogeneous transmissive and storage qualities. The stresses are groundwater withdrawals from wells. The utility of response functions arises from their capacity to be embedded in management models such as decision support systems. The response functions are incorporated into the objective function or constraints that couple the hydrologic system with the management system. Three response -function examples are presented for a hypothetic basin.
    • Hydrogeology in the United States 1780-1950

      Davis, Stanley N.; Davis, Augusta G.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2005-11)
      Most modern textbooks that deal with subsurface water, or hydrogeology, include a brief summary of the historical development of the science. In our book, we have expanded on this general theme without introducing the more technical aspects of the topic. We have, however, emphasized two important points that are commonly overlooked. First, most of the fundamental contributions made during the 1800's were not American but were primarily European. Second, 1885 was the date of the first ground -water publication of the United States Geological Survey, but it did not mark the birth of hydrogeology in the United States. Some American contributions were made about 80 years earlier. The authors are grateful for the assistance of many individuals. T. N. Narasimhan, M. P. Anderson, F. M. Phillips, D. B. Stephens, J. V. Brahana, C. W. Fetter, D. Deming, and D. I. Siegel were given the initial version of our book and provided numerous useful comments.
    • Characterization of aquifer heterogeneity using transient hydraulic tomography

      Zhu, Junfeng; Yeh, Tian-Chyi J.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004-11)
      Hydraulic tomography is a cost -effective technique for characterizing the heterogeneity of hydraulic parameters in the subsurface. During hydraulic tomography surveys, a large number of hydraulic heads (i.e., aquifer responses) are collected from a series of pumping or injection tests in an aquifer. These responses are then used to interpret the spatial distribution of hydraulic parameters of the aquifer using inverse modeling. In this study, we developed an efficient sequential successive linear estimator (SSLE) for interpreting data from transient hydraulic tomography to estimate three-dimensional hydraulic conductivity and specific storage fields of aquifers. We first explored this estimator for transient hydraulic tomography in a hypothetical one-dimensional aquifer. Results show that during a pumping test, transient heads are highly correlated with specific storage at early time but with hydraulic conductivity at late time. Therefore, reliable estimates of both hydraulic conductivity and specific storage must exploit the head data at both early and late times. Our study also shows that the transient heads are highly correlated over time, implying only infrequent head measurements are needed during the estimation. Applying this sampling strategy to a well -posed problem, we show that our SSLE can produce accurate estimates of both hydraulic conductivity and specific storage fields. The benefit of hydraulic tomography for ill -posed problems is then demonstrated. Finally, to affirm the robustness of our SSLE approach, we apply the SSLE approach to transient hydraulic tomography in a hypothetical two- dimensional aquifer with nonstationary hydraulic properties, as well as a hypothetical three-dimensional heterogeneous aquifer.
    • Stochastic analysis of moisture plume dynamics of a field injection experiment

      Ye, Ming; Khaleel, Raziuddin; Yeh, Tian-Chyi J.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004-10)
      A vadose zone field injection experiment was conducted in the summer of 2000 at theHanford Site, Washington. The unique moisture content database is used to identify the lithology at the field site and to interpret, visualize, and quantify the spatio- temporal evolution of the three -dimensional (3 -D) moisture plume created by the injection experiment. We conducted a hierarchical geostatistical analysis to examine the large -scale geologic structure for the entire field site, and then investigate small -scale features within different layers. Afterward, variogram analysis is applied to the O field measured for seven different days during the injection experiment. Temporal variations of sills and ranges are related to the observed moisture plume dynamics. A visualization of the 3 -D moisture plume evolution illustrates effects of media heterogeneity. Statistics of changes in moisture content as a function of distance reveals large variance near the wetting front and the coefficient of variation increases with decreasing mean.These findings support the gradient- and mean -dependent variability in the moisture content distribution as reported by existing stochastic theories. Spatial moment analysis is also conducted to quantify the rate and direction of movement of the plume mass center and its spatial spreading. The ratio of horizontal to vertical spreading at varying moisture contents suggests moisture- dependent anisotropy in effective unsaturated hydraulic conductivity, confirming existing stochastic theories. However, the principal directions of the spatial moments are found to vary as the moisture plume evolves through local heterogeneity, a feature that has not been recognized in the theories.
    • Traditional Aquifer Tests: Comparing Apples to Oranges?

      Wu, Cheng-Mau; Yeh, Tian-Chyi J.; Lee, Tim Hau; Hsu, Nein-Sheng; Chen, Chu-Hui; Sancho, Albert Folch; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004-10)
      Traditional analysis of aquifer tests uses the observed hydrograph at one well caused by pumping at another well for estimating transmissivity and storage coefficient of an aquifer. The analysis relies on Theis' or Jacob's approximate solution, which assumes aquifer homogeneity. Aquifers are inherently heterogeneous at different scales. If the observation well taps into a low permeability zone while the pumping well is located in a high permeable zone, the resulting situation contradicts the homogeneity assumption embedded in the traditional analysis. As a result, a practical but important question we ask: What do we derive from the traditional analysis? Using numerical experiments in synthetic aquifers, we answer this question. Results of the experiments indicate that the effective transmissivity, Teff , and storage coefficient, Seff , values vary with time, as well as the principal directions of the transmissivity, but both values approach their geometric means of the aquifer at large times. Analysis of the estimated transmissivity (T) and storage coefficient (S ) using well hydrographs from a single observation well shows that at early times, both the estimated T and S values vary with time. At late times, both estimates approach local averages near the observation well. The T value approaches but does not equal Teff , representing an average value over a broad area in the vicinity of the observation well while the S value converges to the value dominated by the storage coefficient near the observation wells (i.e., its average area is much smaller than that of the t value).
    • Estimation of effective unsaturated hydraulic conductivity tensor using spatial moments of observed moisture plume

      Yeh, Tian-Chyi J.; Ye, Ming; Khaleel, Raziuddin; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004-10)
      Knowledge of unsaturated zone hydraulic properties is critical for many environmental and engineering applications. Various stochastic methods have been developed during the past two decades to estimate the effective unsaturated hydraulic properties. Independent of these stochastic methods, we develop in this paper a practical approach to estimate the three-dimensional (3 -D) effective unsaturated hydraulic conductivity tensor using spatial moments of 3-D snapshots of a moisture plume under transient flow conditions. approach hydraulic hydraulic Application of the new to a field site in southeastern Washington State yields an effective unsaturated conductivity tensor that exhibits moisture- dependent anisotropy. The effective conductivities compare well with laboratory- measured unsaturated hydraulic conductivity data from small core samples; they also reproduce the general behavior of the observed moisture plume at the site. We also define a moisture diffusivity length concept which we use in conjunction with estimated correlation scales of the geological media at the field site to explain deviations between the observed and simulated plumes based on the derived effective hydraulic properties.
    • A lower San Pedro river basin groundwater flow model

      Whittier, Jonathan Douglas; Maddock, Thomas, III; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004)
      Water issues in the Lower San Pedro River basin in southeastern Arizona are becoming increasingly contentious as urban development, agriculture, and mining needs compete with the needs of the riparian habitat. To better understand the water demands in this basin, a new groundwater flow model has been created. First, the conceptual model was produced using various Geographic Information System (GIS) applications. A new method allocating digital precipitation data to the smaller drainages within the watershed was used to estimate mountain front recharge. Well data was gathered from both the United States Geological Survey (USGS) and Arizona Department of Water Resources (ADWR). Depth to bedrock was interpolated from an earlier gravity survey of the area. The current extent of riparian vegetation was determined by recent United States Forest Service aerial photography. GIS shapefiles were created depicting the data necessary for MODFLOW. Second, the numerical MODFLOW model was formed using GMS (Groundwater Modeling System), a graphical user interface for MODFLOW. GMS was used to create the grid, allocate the information from the shapefiles into MODFLOW input files, create the MODFLOW numerical model, and calibrate the model. The model results project potential impacts to the overall sustainability of groundwater within the basin. In the future, the model will be used as an administrative tool to assess alternative land management scenarios and their abilities to sustain or improve the riparian habitat along the San Pedro River.
    • Evaluation of national weather service ensemble streamflow predictions (ESP) for the Colorado river basin

      Franz, Kristie J.; Hartmann, Holly C.; Sorooshian, Soroosh; Bales, Roger; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2003-01)
      The National Weather Service (NWS) developed the Ensemble Streamflow Prediction (ESP) system to generate probabilistic water supply forecasts that consist of an ensemble of streamflow traces (scenarios) conditioned on the initial states of the basin. Uncertainty information available from ESP may be more useful to risk-based decision makers than what is currently provided by linear regression forecasts. Because the use of ESP has been limited to date, there are few operational forecasts available for verification. Therefore, it was necessary to generate simulated operational ESP forecasts to test the forecasting procedure's potential to enhance current forecasting techniques. Simulated historical forecasts were generated for 14 forecast points in the Colorado River basin. The median and best forecast traces were analyzed as representations of ESP deterministic forecasts. General scalar statistics were used to evaluate these traces. The probability information contained in the entire ensemble was analyzed using probabilistic and conditional verification methods. It was found that the information contained in the median trace is limited and that choosing one trace is not the optimal use of ESP forecast information. ESP provides a probabilistic forecast that performs better than a probabilistic forecast based on climatology. In addition, ESP can provide accurate information about the magnitude of future streamflow discharge even at lead times of up to seven months. With shorter lead times (2-3 months), the forecasts become more informative and accurate.
    • A riparian evapotranspiration package

      Maddock, Thomas, III; Baird, Kathryn J.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2002-10)
      A new evapotranspiration package for the U.S. Geological Survey's groundwater -flow model, MODFLOW, is documented. The Riparian Evapotranspiration Package (RIP-ET), provides flexibility in simulating riparian and wetland evapotranspiration (ET) not provided by the MODFLOW-96 Evapotranspiration (EVT) Package, nor by the MODFLOW-2000 Segmented Function Evapotranspiration (ETS1) Package. This report describes how the package was conceptualized and provides input instructions, listings and explanations of the source code, and an example simulation. Traditional approaches to modeling ET processes assume a piecewise linear relationship between ET flux rate and hydraulic head. The Riparian ET Package replaces this traditional relationship with a segmented, nonlinear dimensionless curve that reflects the eco-physiology of riparian and wetland ecosystems. Evapotranspiration losses from these ecosystems are dependent not only on hydraulic head but on the plant types present. User-defined plant functional groups (PFGs) are used to elucidate the interactive processes of plant ET with groundwater conditions. Five generalized plant functional groups based on transpiration rates, plant rooting depth, and drought tolerance are presented: obligate wetland, shallow-rooted riparian, deep-rooted riparian, transitional riparian and bare ground/open water. Plant functional groups can be further divided into subgroups (PFSG) based on plant size and/or density. The Riparian ET Package allows for partial habitat coverage and mixtures of plant functional subgroups to be present in a single model cell. This requires a determination of fractional coverage for each of the plant functional subgroups present in a cell to simulate the mixture of coverage types and resulting ET. The fractional cover within a cell has three components: 1) fraction of active habitat, 2) fraction of plant functional subgroup in a cell, and 3) fraction of plant canopy area. The Riparian ET package determines the ET rate for each plant functional group in a cell, the total ET in the cell, and the total ET rate over the region of simulation.
    • Stochastic fusion of information for characterizing and monitoring the vadose zone

      Yeh, T.-C. Jim; Simunek, Jirka; Van Genuchten, Martinus Th.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2002-03)
      Inverse problems for vadose zone hydrological processes are often being perceived as ill - posed and intractable. Consequently, solutions to inverse problems are often subject to skepticism. In this paper, using examples, we elucidate difficulties associated with inverse problems and the prerequisites for such problems to be well -posed so that a unique solution exists. We subsequently explain the need of a stochastic conceptualization of the inverse problem and, in turn, the conditional- effective -parameter concept. This concept aims to resolve the ill -posed nature of inverse problems for the vadose zone, for which generally only sparse data are available. Next, the development of inverse methods for the vadose zone, based on a conditional -effective -parameter concept, is explored, including cokriging, the use of a successive linear estimator, and a sequential estimator. Their applications to the vadose zone inverse problems are subsequently examined, which include hydraulic /pneumatic and electrical resistivity tomography surveys, and hydraulic conductivity estimation using observed pressure heads, concentrations, and arrival times. Finally, a stochastic information fusion technology is presented that assimilates information from unsaturated hydraulic tomography and electrical resistivity tomography. This technology offers great promise to effectively characterize heterogeneity, to monitor processes in the vadose zone, and to quantify uncertainty associated with vadose zone characterization and monitoring.
    • Investigations into the availability of additional water supplies and water storage areas for the Santa Cruz active management area, Arizona

      Pranschke, Stephanie; Mac Nish, Robert D.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2002)
      The desert climate of Southern Arizona coupled with the overdraft of its groundwater resources, led to the passing of the 1980, Groundwater Management Act. The Act mandates the creation of management plans in designated areas of heavy overdraft. Of the four initial Active Management Areas (AMAs, three had management plans that were designed to secure sustainable yield of the aquifer by 2025. In 1994, the Arizona legislature created a fifth AMA by designating the southern part of the Tucson AMA as the Santa Cruz AMA (SCAMA). The purpose for this subdivision was to facilitate the bi- national negotiations for coordinated water resource management in this internationally shared basin. Additionally, the SCAMA is to coordinate the management of surface water and groundwater rights for public health, safety and welfare. A.R.S. § 45-411.04. The legislature also assigned the SCAMA the management goals of maintaining safe -yield conditions and preventing long -term declines in local water table levels. A.R.S. § 45- 562(C) (ADWR, 1999). This study is a result of a grant award from the 1999 Augmentation and Conservation Assistance Program in an attempt to investigate the availability of additional water supplies and water storage areas within the SCAMA.
    • Hydrologic resource assessment of upper Sabino Creek basin, Pima county, Arizona

      Peters, Christopher J.; Bales, Roger C.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2001-01)
      A hydrologic resource assessment was performed for upper Sabino Creek basin, using data from a variety of local, state, and Federal agencies and organizations. Hydrologic fluxes were identified and quantified in order to create a monthly water budget. Snowmelt and rainfall are the major inputs to the watershed. Evapotranspiration accounts for the greatest loss of water. Human consumption and streamflow, while important for regulatory and aesthetic reasons, are relatively minor components of the water budget. Evapotranspiration, precipitation, and groundwater recharge / soil moisture account for the greatest fluxes of water in the basin. Precipitation is the most variable hydrologic process in the study area. Over a 47-year period, the greatest amount of water moving through the system in any one month was 6,300 acre-feet in October of 1983. The month with the lowest movement of water was December 1996, with 400 acre-feet. A comparison of Sabino Creek data with the El Niño Southern Oscillation phenomenon shows a strong correlation with precipitation and streamflow in upper Sabino Creek basin.
    • An evaluation of hydrologic and riparian resources in Saguaro National Park, Tucson, Arizona

      Baird, Kathryn J.; Mac Nish, Robert; Guertin, D. Philip; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2001)
      Within Saguaro National Park only Rincon Mountain District contains significant riparian areas. The geologic framework of the Tanque Verde Ridge and Rincon Valley exerts strong control on the hydrology of these riparian systems. Pantano fault constitutes a line of hydrogeologic separation between the occurrence and utilization of groundwater in the Rincon Valley and the main Tucson basin. No known, comparable fault isolates the upper Tanque Verde Creek alluvium from downstream pumping effects. However, east of the confluence with Agua Caliente Wash, the highly permeable alluvial materials are much thinner, and serve to dampen such downstream effects. Therefore, the ground water reservoirs supporting the riparian areas within Rincon Mountain District are not directly connected to the Tucson basin aquifer. In what is described herein as upper basin areas, high gradient tributary streams to Tanque Verde Creek and Rincon Creek have discontinuous bodies of shallow alluvium interspersed with bedrock channel. Alluvium has accumulated behind small faults or resistant bedrock ledges and contains shallow ground water basins that support small pockets of riparian or xeroriparian vegetation. The ground water in these small basins is sustained by seeps or springs, and by runoff from precipitation and is not likely to be connected to a regional ground water system. In what we have characterized as middle basin areas, the stream gradients are less than 25m/km. In these low gradient reaches, the alluvial floodplain sediments are continuous, though not thick, as ledges of more resistant bedrock formations appear in the stream channel. These low gradient reaches contain larger volumes of ground water than the high gradient basins and support more robust riparian vegetation. The ground water in the low gradient reaches is believed to be connected to the regional ground water system. Such a low gradient reach exists in a tributary to Tanque Verde Creek about 1.4 km east of Wentworth Road and extends about 1.6 km into the Park. A similar low gradient reach occurs along Rincon Creek in the Expansion Area, and at the mouths of Chiminea and Madrona Creeks.
    • An analysis of the effects of retiring irrigation pumpage in the San Pedro riparian national conservation area, Cochise county, Arizona

      Sharma, Vandana; Nish, Robert D. Mac; Maddock, Thomas, III; Department of Hydrology & Water Resources, The University of Arizona; Arizona Research Laboratory for Riparian Studies (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2000)
      A seasonal groundwater model was developed to simulate fluxes and head distributions with periodic boundary conditions within the San Pedro Riparian National Conservation Area (SPRNCA) in southeastern Arizona. This model incorporated a seasonal approach for the period 1940-1995. Two years were used to simulate streamflow, 1990 and 1995. The model, as currently calibrated, does not accurately reproduce observed baseflow conditions in the San Pedro River and simulates an exaggerated effect of retiring irrigation within the SPRNCA. The model simulated increased baseflows while the observed baseflows declined at the USGS Charleston stream gage, though increases in baseflow contributions between Hereford Bridge and Lewis Springs have been reported. The original (Corell, et al., 1996) model and the seasonal transient model suffer from over- estimation of discharge from the floodplain aquifer to the San Pedro river, as well as errors in the seasonal transient model's simulation of riparian ET, and seasonal variations in stream conductance. These problems precluded the seasonal transient model from replicating the observed baseflows in the San Pedro river at the Charleston bridge, however, the results of the simulation are thought to be qualitatively indicative of changes in the flow system resulting from the retirement of irrigated agriculture in the San Pedro Riparian National Conservation Area. Possible sources for this problem include replacement of irrigation stresses by the expansion of cones of depression more distant from the river, overestimation of mountain front recharge, poor baseflow estimates and evapotransipration calculations from the stream gages at Charleston and Palominas, and the effects of a recently discovered silt -clay body that may dampen the speed of the rivers response to changes in stress. Additional efforts to re- calibrate the model, taking these areas into account, should provide better simulated baseflow values of the observed data.
    • Simulation of Groundwater Conditions in the Upper San Pedro Basin for the Evaluation of Alternative Futures

      Goode, Tomas Charles; Maddock, Thomas, III; Department of Hydrology & Water Resources, The University of Arizona; University of Arizona Research Laboratory for Riparian Studies (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2000)
      The creation of the groundwater model of the Upper San Pedro Basin included two developmental phases: the creation of a conceptual and numerical model. The creation of the conceptual model was accomplished through the utilization of Geographic Information System (GIS) software, namely ArcView, used primarily to view and create point, line, and polygonal shapes. The creation of a numerical model was accomplished by the infusion of the conceptual model into a 3D finite difference grid used in MODFLOW groundwater software from the U.S. Geological Survey. MODFLOW computes the hydraulic head (water level) for each cell within the grid. The infusion of the two models (conceptual and numerical) was allowed through the use of Department of Defense Groundwater Modeling System (GMS) software. The time period for groundwater modeling began with predevelopment conditions, or "steady state." Steady state conditions were assumed to exist in 1940. The steady state was used as the initial condition for the subsequent transient analysis. The transient simulation applied historical and current information of pumping stresses to the system from 1940 to 1997. After modeling current conditions, Alternative Futures' scenarios were simulated by modifying current stresses and by adding new ones. The possible future impacts of to the hydrologic system were then evaluated.
    • Deciding to Recharge

      Eden, Susanna; Davis, Donald R.; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1999-12)
      Public water policy decision making tends to be too complex and dynamic to be described fully by traditional, rational models. Information intended to improve decisions often is rendered ineffective by a failure to understand the process. An alternative, holistic description of how such decisions actually are made is presented here and illustrated with a case study. The role of information in the process is highlighted. Development of a Regional Recharge Plan for Tucson, Arizona is analyzed as the case study. The description of how decisions are made is based on an image of public water policy decision making as 1) a structured, nested network of individuals and groups with connections to their environment through their senses, mediated by their knowledge; and 2) a nonlinear process in which decisions feed back to affect the preferences and intentions of the people involved, the structure of their interactions, and the environment in which they operate. The analytical components of this image are 1) the decision makers, 2) the relevant features of their environment, 3) the structure of their interactions, and 4) the products or outputs of their deliberations. Policy decisions analyzed by these components, in contrast to the traditional analysis, disclose a new set of relationships and suggest a new view of the uses of information. In context of information use, perhaps the most important output of the decision process is a shared interpretation of the policy issue. This interpretation sets the boundaries of the issue and the nature of issue-relevant information. Participants are unlikely to attend to information incompatible with the shared interpretation. Information is effective when used to shape the issue interpretation, fill specific gaps identified as issue-relevant during the process, rationalize choices, and reshape the issue interpretation as the issue environment evolves.
    • Advances in seasonal forecasting for water management in Arizona: a case study of the 1997-98 El Niño

      Pagano, Thomas; Hartmann, Holly; Sorooshian, Soroosh; Bales, Roger; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1999-11)
      This 1997-98 El Niño provided a unique opportunity for climate information and forecasts to be utilized by water management agencies in the Southwestern U.S. While Arizona has experienced high streamflow associated with previous El Niño events, never before had an event of such magnitude been predicted with advance warning of several months. Likewise, the availability of information, including Internet sources and widespread media coverage, was higher than ever before. Insights about use of this information in operational water management decision processes are developed through a series of semi -structured in -depth interviews with key personnel from a broad array of agencies responsible for emergency management and water supply, with jurisdictions ranging from urban to rural and local to regional. The interviews investigate where information was acquired, how it was interpreted and how it was incorporated into specific decisions and actions. The interviews also investigate agency satisfaction with the products available to them, their operational decisions, and intentions to utilize forecast products in the future. Study findings lead to recommendations about how to more effectively provide intended users of forecasts with information required to enact mitigation measures and utilize opportunities that some climatic events present. The material presented in this report is primarily based on the Masters Thesis of Thomas Pagano.
    • A multi-step automatic calibration scheme (MACS) for river forecasting models utilizing the national weather service river forecast system (NWSRFS)

      Sorooshian, Soroosh; Gupta, Hoshin; Hogue, Terri S.; Holz, Andrea; Braatz, Dean; Department of Hydrology & Water Resources, The University of Arizona (Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1999-10)
      Traditional model calibration by National Weather Service (NWS) River Forecast Center (RFC) hydrologists involves a laborious and time -consuming manual estimation of numerous parameters. The National Weather Service River Forecasting System (NWSRFS), a software system used by the RFCs for hydrologic forecasting, includes an automatic optimization program (OPT3) to aid in model calibration. The OPT3 program is not used operationally by the majority of RFC hydrologists who perform calibration studies. Lack of success with the traditional single - step, single-criterion automatic calibration approach has left hydrologists more comfortable employing a manual step-by-step process to estimate parameters. This study develops a Multistep Automatic Calibration Scheme (MACS), utilizing OPT3, for the river forecasting models used by the RFCs: the Sacramento Soil Moisture Accounting (SAC-SMA). and SNOW-17 models. Sixteen parameters are calibrated in three steps, replicating the progression of manual calibration steps used by NWS hydrologists. MACS is developed by minimizing different objective functions for different parameters in a step -wise manner. Model runs are compared using the MACS optimized parameters and the manually estimated parameters for six basins in the North Central River Forecast Center (NCRFC) forecast area. Results demonstrate that the parameters obtained via the MACS procedure generally yield better model performance than those obtained by manual calibration. The MACS methodology is a time-saving approach that can provide prompt model forecasts for NWS watersheds.