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At least 469 records · Page 26Linked to original sources

Flood of July 12-13, 2004, Burlington and Camden Counties, South-Central New Jersey

Intense rainfall inundated south-central New Jersey on July 12-13, 2004, causing major flooding with heavy property, road, and bridge damage in Burlington and Camden Counties. Forty-five dams were topped or damaged, or failed completely. The affected areas were in the Rancocas Creek, Cooper River, and Pennsauken Creek Basins. The U.S. Geological Survey (USGS) documented peak stream elevations and flows at 56 selected sites within the affected area. With rainfall totals averaging more than 6 inches throughout the three basins, peak-of-record flood elevations and streamflows occurred at all but one USGS stream gage, where the previous record was tied. Flood-frequency recurrence-intervals ranged from 30 to greater than 100 years and maximum streamflow per square mile ranged from 13.9 to 263 cubic feet per second per square mile (ft3/s/mi2). Peak streamflow at USGS stream gages surrounding the affected basins are associated with considerably lower recurrence intervals and demonstrate the limited extent of the flood. A high tide of about 1 foot above monthly mean high tide did not contribute to high-water conditions. Low ground-water levels prior to the rainfall helped to mitigate flooding in the affected basins. Compared with historical floods in the Rancocas Creek Basin during 1938-40, the July 2004 flood had greater streamflow, but lower stream elevations. Property damage from the event was estimated at $50 million. Governor James E. McGreevy declared a State of Emergency in Burlington and Camden Counties on July 13, 2004. After assessment of the damage by the Federal Emergency Management Agency (FEMA), President George W. Bush declared Burlington and Camden Counties disaster areas on July 16, 2004.

Scientific Investigations Report↗

The Amphibian Research and Monitoring Initiative (ARMI): 5-year report

The Amphibian Research and Monitoring Initiative (ARMI) is an innovative, multidisciplinary program that began in 2000 in response to a congressional directive for the Department of the Interior to address the issue of amphibian declines in the United States. ARMI’s formulation was cross-disciplinary, integrating U.S. Geological Survey scientists from Biology, Water, and Geography to develop a course of action (Corn and others, 2005a). The result has been an effective program with diverse, yet complementary, expertise. ARMI’s approach to research and monitoring is multiscale. Detailed investigations focus on a few species at selected local sites throughout the country; monitoring addresses a larger number of species over broader areas (typically, National Parks and National Wildlife Refuges); and inventories to document species occurrence are conducted more extensively across the landscape. Where monitoring is conducted, the emphasis is on an ability to draw statistically defensible conclusions about the status of amphibians. To achieve this objective, ARMI has instituted a monitoring response variable that has nationwide applicability. At research sites, ARMI focuses on studying species/environment interactions, determining causes of observed declines, and developing new techniques to sample populations and analyze data. Results from activities at all scales are provided to scientists, land managers, and policymakers, as appropriate. The ARMI program and the scientists involved contribute significantly to understanding amphibian declines at local, regional, national, and international levels. Within National Parks and National Wildlife Refuges, findings help land managers make decisions applicable to amphibian conservation. For example, the National Park Service (NPS) selected amphibians as a vital sign for several of their monitoring networks, and ARMI scientists provide information and assistance in developing monitoring methods for this NPS effort. At the national level, ARMI has had major exposure at a variety of meetings, including a dedicated symposium at the 2004 joint meetings of the Herpetologists’ League, the American Society of Ichthyologists and Herpetologists, and the Society for the Study of Amphibians and Reptiles. Several principal investigators have brought international exposure to ARMI through venues such as the World Congress of Herpetology in South Africa in 2005 (invited presentation by Dr. Gary Fellers), the Global Amphibian Summit, sponsored by the International Union for Conservation of Nature (IUCN) and Wildlife Conservation International, in Washington, D.C., 2005 (invited participation by Dr. P.S. Corn), and a special issue of the international herpetological journal Alytes focused on ARMI in 2004 (edited by Dr. C.K. Dodd, Jr.). ARMI research and monitoring efforts have addressed at least 7 of the 21 Threatened and Endangered Species listed by the U.S. Fish and Wildlife Service (California red-legged frog [Rana draytonii], Chiricahua leopard frog [R. chiricahuensis], arroyo toad [Bufo californicus], dusky gopher frog [Rana sevosa], mountain yellow-legged frog [R. muscosa], flatwoods salamander [Ambystoma cingulatum], and the golden coqui [Eleutherodactylus jasperi]), and 9 additional species of concern recognized by the IUCN. ARMI investigations have addressed time-sensitive research, such as emerging infectious diseases and effects on amphibians related to natural disasters like wildfire, hurricanes, and debris flows, and the effects of more constant, environmental change, like urban expansion, road development, and the use of pesticides. Over the last 5 years, ARMI has partnered with an extensive list of government, academic, and private entities. These partnerships have been fruitful and have assisted ARMI in developing new field protocols and analytic tools, in using and refining emerging technologies to improve accuracy and efficiency of data handling, in conducting amphibian disease, malformation, and environmental effects research, and in implementing a network of monitoring and research sites. Accomplishments from these endeavors include more than 40 publications on amphibian status and trends, nearly 100 publications on amphibian ecology and causes of declines, and over 30 methodological publications. Several databases have emerged as a result of ARMI and its partnerships; one, a digital atlas of ranges for all U.S. amphibian species, was used by the IUCN to display amphibian distribution maps in the Global Amphibian Assessment Project. Given the scope of ARMI and the panoply of projects, findings have had implications for policy. Investigations that demonstrate amphibian declines or illuminate causes of declines provide valuable information about habitat management, environmental effects, mechanisms for the spread of disease, and human/amphibian interfaces. This information has been made available to land managers, scientists, educators, Congress and other policymakers, and the public. The support afforded ARMI by Congress has been influential in the program’s development and success. The value of ARMI’s efforts will continue to increase as we are able to extend our studies spatially and temporally to answer critical questions with more confidence. We are using ARMI’s resources efficiently and continuing to develop innovative mechanisms for leveraging resources for maximum effectiveness during challenging financial times. This report is a 5-year retrospective of the structure, methodology, progress, and contributions to the broader scientific community that have resulted from this national USGS program. We evaluate ARMI’s success to date, with regard to the challenges faced by the program and the strengths that have emerged. We chart objectives for the next 5 years that build on current accomplishments, highlight areas meriting further research, and direct efforts to overcome existing weaknesses.

Scientific Investigations Report↗

Peak Discharge, Flood Profile, Flood Inundation, and Debris Movement Accompanying the Failure of the Upper Reservoir at the Taum Sauk Pump Storage Facility near Lesterville, Missouri

The Taum Sauk pump-storage hydroelectric power plant located in Reynolds County, Missouri, uses turbines that operate as pumps and hydraulic head generated by discharging water from an upper to a lower reservoir to produce electricity. A 55-acre upper reservoir with a 1.5- billion gallon capacity was built on top of Proffit Mountain, approximately 760 feet above the floodplain of the East Fork Black River. At approximately 5:16 am on December 14, 2005, a 680-foot wide section of the upper reservoir embankment failed suddenly, sending water rushing down the western side of Proffit Mountain and emptying into the floodplain of East Fork Black River. Flood waters from the upper reservoir flowed downstream through Johnson's Shut-Ins State Park and into the lower reservoir of the East Fork Black River. Floods such as this present unique challenges and opportunities to analyze and document peak-flow characteristics, flood profiles, inundation extents, and debris movement. On December 16, 2005, Light Detection and Ranging (LiDAR) data were collected and used to support hydraulic analyses, forensic failure analyses, damage extent, and mitigation of future disasters. To evaluate the impact of sedimentation in the lower reservoir, a bathymetric survey conducted on December 22 and 23, 2005, was compared to a previous bathymetric survey conducted in April, 2005. Survey results indicated the maximum reservoir capacity difference of 147 acre-feet existed at a pool elevation of 730 feet. Peak discharge estimates of 289,000 cubic feet per second along Proffit Mountain and 95,000 cubic feet per second along the East Fork Black River were determined through indirect measurement techniques. The magnitude of the embankment failure flood along the East Fork Black River was approximately 4 times greater than the 100-year flood frequency estimate of 21,900 cubic feet per second, and approximately 3 times greater than the 500-year flood frequency estimate of 30,500 cubic feet per second. Dynamic wave unsteady flow models Dam Break (DAMBRK) and Unsteady NETwork (UNET) were used to route the flood wave from the embankment failure breach of the upper reservoir to the spillway of the lower reservoir. Simulated velocities ranged from 20 to 51 feet per second along Proffit Mountain and 12 to 32 feet per second along the East Fork Black River. Simulated arrival time of the flood wave took approximately 5.5 to 6.0 minutes to enter into the floodplain of the East Fork Black River, and roughly 29 minutes to begin filling the lower reservoir. Simulated shear stress values reached as high as 232 pounds per square foot along the slope of Proffit Mountain and 144 pounds per square foot within the Shut-Ins. Flood depths from the embankment failure may have reached greater than 50 feet along Proffit Mountain and as much as 30 to 40 feet along the East Fork Black River. A steady-state model was used to develop 2-, 5-, 10-, 25-, 50-, 100-, and 500-year flood frequency profiles along the East Fork Black River. A similar flood event, hypothetically resulting from a breach of the east embankment above Taum Sauk Creek, was simulated along with the 100- and 500-year flood profiles on Taum Sauk Creek. Estimated extents of flood inundation were developed for each profile. Debris movement was extensive as a result of the flood wave moving down Proffit Mountain and through Johnson's Shut-Ins State Park. A quantitative assessment of debris movement was conducted to benefit rehabilitation efforts within the park. Approximately 180 acres of timber were affected as a result of the embankment failure flood.

Scientific Investigations Report↗

Flood of April 2-4, 2005, Delaware River Main Stem from Port Jervis, New York, to Cinnaminson, New Jersey

Several conditions, including saturated soils, snowmelt, and heavy rains, caused flooding on the Delaware River on April 2-4, 2005. The event occurred 50 years after the historic 1955 Delaware River flood, and only six months after a smaller but equally notable flood on September 18-19, 2004. The Delaware River flooded for a third time in 22 months in June, 2006. The peak flows and elevations of the 2005 flood were similar to those on June 28-29, 2006. The following report describes the April 2-4, 2005, Delaware River flood, and includes the associated precipitation amounts, peak flows and elevations, and flood frequencies. A comparison of historic Delaware River floods also is presented. The appendix of the report contains detailed information for 156 high-water mark elevations obtained on the main stem of the Delaware River from Port Jervis, New York, to Cinnaminson, New Jersey, for the April 2-4, 2005 flood. The April 2005 event originated with frequent precipitation from December 2004 to March 2005 which saturated the soils in the upper Delaware River Basin. The cold winter froze some of the soils and left a snowpack at higher elevations equivalent to as much as 10 inches of water in some areas. Temperatures rose above freezing, and heavy rains averaging 1 to 3 inches on March 27, 2005, melted some of the snow, causing the Delaware River to rise; however, peak elevations were still 2 to 7 feet below flood stage. Another round of rainfall averaging 2-5 inches in the basin on April 2, 2005, melted the remaining snowpack. The combination of snowmelt and runoff from the two storms produced flood conditions along the main stem of the Delaware River. Flood frequencies of flows at selected tributaries to the Delaware River did not exceed the 35-year recurrence intervals. The Delaware River main stem peak-flow recurrence intervals ranged from 40 to 80 years; flows were approximately 20 percent less than those from the peak of record in 1955. Peak elevations exceeded National Weather Service flood stages defined at continuous-record streamflow-gaging stations by 5 to 7 feet, but were on average 3 to 5 feet lower than the peak of record in August 1955. Peak elevations determined at 48 sites along the main stem of the Delaware River defined the flood profile between the gaging stations. The peak elevation in the tide-effected portion of the Delaware (downstream of Trenton, New Jersey), occurred on April 2, 2 days before the riverine peak, as a result of water pushed into the bay by a low-pressure system situated just off the coast. Every county located along the main stem of the Delaware River was declared a Federal disaster area. Property damage estimates in Pennsylvania, New York, and New Jersey exceeded $200 million.

Scientific Investigations Report↗

Flood of June 22-24, 2006, in North-Central Ohio, With Emphasis on the Cuyahoga River Near Independence

Heavy rains caused severe flooding on June 22-24, 2006, and damaged approximately 4,580 homes and 48 businesses in Cuyahoga County. Damage estimates in Cuyahoga County for the two days of flooding exceed $47 million; statewide damage estimates exceed $150 million. Six counties (Cuyahoga, Erie, Huron, Lucas, Sandusky, and Stark) in northeast Ohio were declared Federal disaster areas. One death, in Lorain County, was attributed to the flooding. The peak streamflow of 25,400 cubic feet per second and corresponding peak gage height of 23.29 feet were the highest recorded at the U.S. Geological Survey (USGS) streamflow-gaging station Cuyahoga River at Independence (04208000) since the gaging station began operation in 1922, exceeding the previous peak streamflow of 24,800 cubic feet per second that occurred on January 22, 1959. An indirect calculation of the peak streamflow was made by use of a step-backwater model because all roads leading to the gaging station were inundated during the flood and field crews could not reach the station to make a direct measurement. Because of a statistically significant and persistent positive trend in the annual-peak-streamflow time series for the Cuyahoga River at Independence, a method was developed and applied to detrend the annual-peak-streamflow time series prior to the traditional log-Pearson Type III flood-frequency analysis. Based on this analysis, the recurrence interval of the computed peak streamflow was estimated to be slightly less than 100 years. Peak-gage-height data, peak-streamflow data, and recurrence-interval estimates for the June 22-24, 2006, flood are tabulated for the Cuyahoga River at Independence and 10 other USGS gaging stations in north-central Ohio. Because flooding along the Cuyahoga River near Independence and Valley View was particularly severe, a study was done to document the peak water-surface profile during the flood from approximately 2 miles downstream from the USGS streamflow-gaging station at Independence to approximately 2 miles upstream from the gaging station. High-water marks were identified and flagged in the field. Third-order-accuracy surveys were used to determine elevations of the high-water marks, and the data were tabulated and plotted.

Scientific Investigations Report↗

Earth science and public health: Proceedings of the Second National Conference on USGS Health-Related Research

The mission of the U.S. Geological Survey (USGS) is to serve the Nation by providing reliable scientific information to describe and understand the earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. As the Nation?s largest water, earth, and biological science and civilian mapping agency, the USGS can play a significant role in providing scientific knowledge and information that will improve our understanding of the relations of environment and wildlife to human health and disease. USGS human health-related research is unique in the Federal government because it brings together a broad spectrum of natural science expertise and information, including extensive data collection and monitoring on varied landscapes and ecosystems across the Nation. USGS can provide a great service to the public health community by synthesizing the scientific information and knowledge on our natural and living resources that influence human health, and by bringing this science to the public health community in a manner that is most useful. Partnerships with health scientists and managers are essential to the success of these efforts. USGS scientists already are working closely with the public health community to pursue rigorous inquiries into the connections between natural science and public health. Partnering agencies include the Armed Forces Institute of Pathology, Agency for Toxic Substances Disease Registry, Centers for Disease Control and Prevention, U.S. Environmental Protection Agency, Food and Drug Administration, Mine Safety and Health Administration, National Cancer Institute, National Institute of Allergy and Infectious Disease, National Institute of Environmental Health Sciences, National Institute for Occupational Safety and Health, U.S. Public Health Service, and the U.S. Army Medical Research Institute of Infectious Diseases. Collaborations between public health scientists and earth scientists can lead to improved solutions for existing and emerging environmental health problems. This report summarizes the presentations and discussions held at the Second National Conference on USGS Health-Related Research, held at the USGS national headquarters in Reston, Virginia. The report presents 68 abstracts of technical presentations made at the conference and summaries of six topical breakout sessions. The abstracts cover a broad range of issues and demonstrate connections between human health and the quality and condition of our environment and wildlife. The summaries of the topical breakout sessions present ideas for advancing interdisciplinary science in areas of earth science and human health.

Scientific Investigations Report↗

Flood of May 2006 in York County, Maine

A stalled low-pressure system over coastal New England on Mother's Day weekend, May 13-15, 2006, released rainfall in excess of 15 inches. This flood (sometimes referred to as the 'Mother's Day flood') caused widespread damage to homes, businesses, roads, and structures in southern Maine. The damage to public property in York County was estimated to be $7.5 million. As a result of these damages, a presidential disaster declaration was enacted on May 25, 2006, for York County, Maine. Peak-flow recurrence intervals for eight of the nine streams studied were calculated to be greater than 500 years. The peak-flow recurrence interval of the remaining stream was calculated to be between a 100-year and a 500-year interval. This report provides a detailed description of the May 2006 flood in York County, Maine. Information is presented on peak streamflows and peak-flow recurrence intervals on nine streams, peak water-surface elevations for 80 high-water marks at 25 sites, hydrologic conditions before and after the flood, comparisons with published Flood Insurance Studies, and places the May 2006 flood in context with historical floods in York County. At sites on several streams, differences were observed between peak flows published in the Flood Insurance Studies and those calculated for this study. The differences in the peak flows from the published Flood Insurance Studies and the flows calculated for this report are within an acceptable range for flows calculated at ungaged locations, with the exception of those for the Great Works River and Merriland River. For sites on the Mousam River, Blacksmith Brook, Ogunquit River, and Cape Neddick River, water-surface elevations from Flood Insurance Studies differed with documented water-surface elevations from the 2006 flood.

Scientific Investigations Report↗

Flood of April 2007 in Southern Maine

Up to 8.5 inches of rain fell from April 15 through 18, 2007, in southern Maine. The rain - in combination with up to an inch of water from snowmelt - resulted in extensive flooding. York County, Maine, was declared a presidential disaster area following the event. The U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency (FEMA), determined peak streamflows and recurrence intervals at 24 locations and peak water-surface elevations at 63 sites following the April 2007 flood. Peak streamflows were determined with data from continuous-record streamflow-gaging stations where available and through hydraulic models where station data were not available. The flood resulted in peak streamflows with recurrence intervals greater than 100 years throughout most of York County, and recurrence intervals up to 50 years in Cumberland County. Peak flows for selected recurrence intervals varied from less than 10 percent to greater than 100 percent different than those in the current FEMA flood-insurance studies due to additional data or newer regression equations. Water-surface elevations observed during the April 2007 flood were bracketed by elevation profiles in FEMA flood-insurance studies with the same recurrence intervals as the recurrence intervals bracketing the observed peak streamflows at seven sites, with higher elevation-profile recurrence intervals than streamflow recurrence intervals at six sites, and with lower elevation-profile recurrence intervals than streamflow recurrence intervals at one site. The April 2007 flood resulted in higher peak flows and water-surface elevations than the flood of May 2006 in coastal locations in York County, and lower peak flows and water-surface elevations than the May 2006 flood further from the coast and in Cumberland County. The Mousam River watershed with over 13 dams and reservoirs was severely impacted by both events. Analyses indicate that the April 2007 peak streamflows in the Mousam River watershed occurred despite the fact that up to 287 million ft3 of runoff was stored by 13 dams and reservoirs.

Scientific Investigations Report↗

Flood of April 2007 and flood-frequency estimates at streamflow-gaging stations in western Connecticut

A spring nor’easter affected the East Coast of the United States from April 15 to 18, 2007. In Connecticut, rainfall varied from 3 inches to more than 7 inches. The combined effects of heavy rainfall over a short duration, high winds, and high tides led to widespread flooding, storm damage, power outages, evacuations, and disruptions to traffic and commerce. The storm caused at least 18 fatalities (none in Connecticut). A Presidential Disaster Declaration was issued on May 11, 2007, for two counties in western Connecticut—Fairfield and Litchfield. This report documents hydrologic and meteorologic aspects of the April 2007 flood and includes estimates of the magnitude of the peak discharges and peak stages during the flood at 28 streamflow-gaging stations in western Connecticut. These data were used to perform flood-frequency analyses. Flood-frequency estimates provided in this report are expressed in terms of exceedance probabilities (the probability of a flood reaching or exceeding a particular magnitude in any year). Flood-frequency estimates for the 0.50, 0.20, 0.10, 0.04, 0.02, 0.01, and 0.002 exceedance probabilities (also expressed as 50-, 20-, 10-, 4-, 2-, 1-, and 0.2- percent exceedance probability, respectively) were computed for 24 of the 28 streamflow-gaging stations. Exceedance probabilities can further be expressed in terms of recurrence intervals (2-, 5-, 10-, 25-, 50-, 100-, and 500-year recurrence interval, respectively). Flood-frequency estimates computed in this study were compared to the flood-frequency estimates used to derive the water-surface profiles in previously published Federal Emergency Management Agency (FEMA) Flood Insurance Studies. The estimates in this report update and supersede previously published flood-frequency estimates for streamflowgaging stations in Connecticut by incorporating additional years of annual peak discharges, including the peaks for the April 2007 flood. In the southwest coastal region of Connecticut, the April 2007 peak discharges for streamflow-gaging stations with records extending back to 1955 were the second highest peak discharges on record; the 1955 annual peak discharges are the highest peak discharges in the station records. In the Housatonic and South Central Coast Basins, the April 2007 peak discharges for streamflow-gaging stations with records extending back to 1930 or earlier ranked between the fourth and eighth highest discharges on record, with the 1936, 1938, and 1955 floods as the largest floods in the station records. The peak discharges for the April 2007 flood have exceedance probabilities ranging between 0.10 to 0.02 (a 10- to 2-percent chance of being exceeded in a given year, respectively) with the majority (80 percent) of the stations having exceedance probabilities between 0.10 to 0.04. At three stations—Norwalk River at South Wilton, Pootatuck River at Sandy Hook, and Still River at Robertsville—the April 2007 peak discharges have an exceedance probability of 0.02. Flood-frequency estimates made after the April 2007 flood were compared to flood-frequency estimates used to derive the water-surface profiles (also called flood profiles) in FEMA Flood Insurance Studies developed for communities. In general, the comparison indicated that at the 0.10 exceedance probability (a 10-percent change of being exceeded in a given year), the discharges from the current (2007) flood-frequency analysis are larger than the discharges in the FEMA Flood Insurance Studies, with a median change of about +10 percent. In contrast, at the 0.01 exceedance probability (a 1-percent change of being exceeded in a year), the discharges from the current flood-frequency analysis are smaller than the discharges in the FEMA Flood Insurance Studies, with a median change of about -13 percent. Several stations had more than + 25 percent change in discharges at the 0.10 exceedance probability and are in the following communities: Winchester (Still River at Robertsville, +50 percent change); Hamden (Mill River near Hamden, +46 percent change); Woodbury (Weekeepeemee River at Hotchkissville, +29 percent change); and Newtown (Pootatuck River at Sandy Hook , +28 percent change). Although the majority of the streamflow-gaging stations had discharges at the 0.01 exceedance probability smaller than in the Flood Insurance Studies, the (2007) flood-frequency estimates were larger than in the Flood Insurance Studies for stations in the following communities: Hamden (Mill River near Hamden, +53 percent change); Thomaston (Naugatuck River at Thomaston, +27 percent change); Newtown (Pootatuck River at Sandy Hook, +18 percent change); and Wallingford (Quinnipiac River at Wallingford, +13 percent change). The 1-percent exceedance probability (100-year flood) elevations at streamflow-gaging stations exceeded the FEMA projected 100-year flood elevations by more than +0.5 feet in two Flood Insurance Studies in the communities of Wallingford (Quinnipiac River at Wallingford, +0.6 feet change) and Hamden (Mill River near Hamden, + 2.3 feet change).

Connecticut↗

Porphyry copper assessment of Southeast Asia and Melanesia: Chapter D in Global mineral resource assessment

The U.S. Geological Survey collaborated with member countries of the Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP) on an assessment of the porphyry copper resources of Southeast Asia and Melanesia as part of a global mineral resource assessment. The region hosts world-class porphyry copper deposits and underexplored areas that are likely to contain undiscovered deposits. Examples of known porphyry copper deposits include Batu Hijau and Grasberg in Indonesia; Panguna, Frieda River, and Ok Tedi in Papua New Guinea; and Namosi in Fiji. This assessment covers the countries of Cambodia, Indonesia, Lao People&rsquo;s Democratic Republic, Malaysia, Myanmar, Papua New Guinea, Singapore, Thailand, and parts of southeastern China, India, the Solomon Islands, Vanuatu, and Fiji. Twenty-two geographic areas were delineated as tracts that are permissive for porphyry copper deposits in Southeast Asia. Permissive tracts are grouped into four broadly defined geographic/geologic areas, as follows: (1) the Indochina Peninsula area, (2) Indonesian and Malaysian Islands, (3) New Guinea Island and Papuan New Guinea islands, and (4) Melanesia. Individual tracts range from less than 1,000 to more than 350,000 square kilometers in area. Permissive tracts are based on mapped and inferred subsurface (<1 kilometer depth) distributions of igneous rocks of specific age ranges that define magmatic arcs and magmatic belts that are likely to contain porphyry copper deposits. Most of these magmatic arcs are subduction-related, although some have porphyry-style deposits occurring in postcollisional and (or) poorly understood tectonic settings. Although maps at a variety of different scales were used in the compilation, the final tract boundaries are intended for use at a scale of 1:1,000,000. Global grade and tonnage models for porphyry copper deposits were evaluated. Most of the known deposits are best described as fitting the copper-gold (Cu-Au) subtype of porphyry copper deposit. For some permissive tracts, a general porphyry copper-gold-molybdenum (Cu-Au-Mo) model was used. Assessment participants estimated numbers of undiscovered deposits at different levels of confidence for most of the permissive tracts. These estimates were combined with grade and tonnage models using a Monte Carlo simulation to estimate undiscovered resources. Additional resources in extensions of deposits with identified resources were not evaluated. Assessment results, presented in tables and graphs, show mean amounts of metal and mineralized rock in undiscovered deposits at different quantile levels, as well as the arithmetic mean for each tract. This assessment estimated a mean of 89 undiscovered porphyry copper deposits for the assessed permissive tracts in Southeast Asia and Melanesia. About 288 million metric tons (Mt) of copper and 18,000 metric tons (t) of gold, as well as byproduct molybdenum and silver, could be associated with undiscovered deposits. This represents about four times the number of deposits with identified resources (23) already discovered in Southeast Asia; reliable reported identified resources for those 23 deposits total 84 Mt of copper and 6,000 t of gold. Eleven permissive tracts have no known porphyry copper deposits with reported resources. Three of those 11 tracts lacked sufficient information for a probabilistic assessment and are discussed in qualitative terms. On a regional basis, both the Indochina Peninsula area and the Indonesian-Malaysian Islands area are estimated to contain about 10 times as much in place copper in undiscovered porphyry copper deposits as has been identified to date. For the New Guinea Island areas, the ratio of undiscovered to identified copper resources is about 2. Some parts of the region have a long history of porphyry exploration cycles and mine development, interrupted at times by political and social unrest, environmental concerns, and natural disasters. Changes in mining laws within the region and the recent high price of gold on the world market have prompted renewed interest in porphyry copper deposits in Southeast Asia and Melanesia. However, predicted undiscovered deposits may not be found, and if found, may not be developed. This assessment includes an overview of the assessment results with summary tables. Detailed descriptions of each tract are included in appendixes, with estimates of numbers of undiscovered deposits, and probabilistic estimates of amounts of copper, molybdenum, gold, and silver that could be contained in undiscovered deposits for each permissive tract. A geographic information system (GIS) that accompanies the report includes tract boundaries and a database of known porphyry copper deposits and significant prospects.

Scientific Investigations Report↗

Porphyry copper assessment of East and Southeast Asia: Philippines, Taiwan (Republic of China), Republic of Korea (South Korea), and Japan

The U.S. Geological Survey collaborated with member countries of the Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP) on an assessment of the porphyry copper resources of East and Southeast Asia as part of a global mineral resource assessment. The assessment covers the Philippines in Southeast Asia, and the Republic of Korea (South Korea), Taiwan (Province of China), and Japan in East Asia. The Philippines host world class porphyry copper deposits, such as the Tampakan and Atlas deposits. No porphyry copper deposits have been discovered in the Republic of Korea (South Korea), Taiwan (Province of China), or Japan. Thirteen geographic areas were delineated as tracts that are permissive for porphyry copper deposits in the assessed area. Individual tracts range from about 3,000 to 100,000 square kilometers in area. Permissive tracts are delineated on the basis of mapped distributions of igneous rocks of specific age ranges that define subduction-related magmatic arcs or magmatic belts that might contain porphyry copper deposits. Most of these magmatic arcs are subduction related, although some porphyry deposits and prospects are present in back-arc or poorly understood tectonic settings. Maps at various scales were used in the compilation; however, the final tract boundaries are intended for use at a scale of 1:1,000,000. Numbers of undiscovered deposits were estimated at different levels of confidence for 10 permissive tracts in the Philippines including one area that extends to eastern Taiwan (Republic of China); permissive tracts in South Korea and Japan are discussed qualitatively. Estimates of numbers of undiscovered deposits were combined with grade and tonnage models using Monte Carlo simulation to estimate amounts of undiscovered resources. Grades and tonnages of known porphyry copper deposits in the study area were compared with global grade and tonnage models to determine the appropriate model for simulation of undiscovered resources. Most of the known deposits are best described as copper-gold subtypes of porphyry copper deposits. For some permissive tracts, a general porphyry copper-gold-molybdenum model was used. Thirty-eight porphyry copper deposits are known in the Philippines; the mean number of undiscovered deposits was estimated to be 28. Mean (arithmetic) resources that could be associated with the undiscovered deposits are 90 million metric tons of copper and 5,800 metric tons of gold, as well as byproduct molybdenum and silver. Additional resources that could be discovered in extensions to known deposits were not evaluated. Assessment results, presented in tables and graphs, indicate expected amounts of total contained metal and mineralized rock in undiscovered deposits at different quantile levels, as well as the arithmetic mean for each tract. The Philippines have a long history of porphyry exploration cycles and mine development, interrupted at times by political and social unrest, environmental concerns, and natural disasters. Changes in mining laws within the region and the recent high price of gold on the world market have prompted renewed interest in porphyry copper deposits in the region. South Korea and Japan have been thoroughly explored for many types of mineral deposits. Available data suggest that the permissive rocks in South Korea typically are too deeply eroded to preserve porphyry copper deposits. Porphyry copper systems may be present in Japan, but are likely to lie at depths greater than the 1 kilometer from the surface protocol adopted for this study. Descriptions of the geologic basis for delineating each tract, the data used, the geologic criteria and rationale for the assessment, and results of the assessment are included in appendixes along with the description of a geographic information system (GIS) that includes tract boundaries, known porphyry copper deposits and significant prospects, and assessment results.

Scientific Investigations Report↗

Magnitude and extent of flooding at selected river reaches in western Washington, January 2009

A narrow plume of warm, moist tropical air produced prolonged precipitation and melted snow in low-to-mid elevations throughout western Washington in January 2009. As a result, peak-of-record discharges occurred at many long-term streamflow-gaging stations in the region. A disaster was declared by the President for eight counties in Washington State and by May 2009, aid payments by the Federal Emergency Management Agency (FEMA) had exceeded $17 million. In an effort to document the flood and to obtain flood information that could be compared with simulated flood extents that are commonly prepared in conjunction with flood insurance studies by FEMA, eight stream reaches totaling 32.6 miles were selected by FEMA for inundation mapping. The U.S. Geological Survey?s Washington Water Science Center used a survey-grade global positioning system (GPS) the following summer to survey high-water marks (HWMs) left by the January 2009 flood at these reaches. A Google Maps (copyright) application was developed to display all HWM data on an interactive mapping tool on the project?s web site soon after the data were collected. Water-surface profiles and maps that display the area and depth of inundation were produced through a geographic information system (GIS) analysis that combined surveyed HWM elevations with Light Detection and Ranging (LiDAR)-derived digital elevation models of the study reaches and surrounding terrain. In several of the reaches, floods were well confined in their flood plains and were relatively straightforward to map. More common, however, were reaches with more complicated hydraulic geometries where widespread flooding resulted in flows that separated from the main channel. These proved to be more difficult to map, required subjective hydrologic judgment, and relied on supplementary information, such as aerial photographs and descriptions of the flooding from local landowners and government officials to obtain the best estimates of the extent of flooding.

Scientific Investigations Report↗

Floods of September 2010 in Southern Minnesota

During September 22-24, 2010, heavy rainfall ranging from 3 inches to more than 10 inches caused severe flooding across southern Minnesota. The floods were exacerbated by wet antecedent conditions, where summer rainfall totals were as high as 20 inches, exceeding the historical average by more than 4 inches. Widespread flooding that occurred as a result of the heavy rainfall caused evacuations of hundreds of residents, and damages in excess of 64 million dollars to residences, businesses, and infrastructure. In all, 21 counties in southern Minnesota were declared Federal disaster areas. Peak-of-record streamflows were recorded at nine U.S. Geological Survey and three Minnesota Department of Natural Resources streamgages as a result of the heavy rainfall. Flood-peak gage heights, peak streamflows, and annual exceedance probabilities were tabulated for 27 U.S. Geological Survey and 5 Minnesota Department of Natural Resources streamgages and 5 ungaged sites. Flood-peak streamflows in 2010 had annual exceedance probabilities estimated to be less than 0.2 percent (recurrence interval greater than 500 years) at 7 streamgages and less than 1 percent (recurrence interval greater than 100 years) at 5 streamgages and 4 ungaged sites. High-water marks were identified and tabulated for the most severely affected communities of Faribault along the Cannon and Straight Rivers, Owatonna along the Straight River and Maple Creek, Pine Island along the North Branch and Middle Fork Zumbro River, and Zumbro Falls along the Zumbro River. The nearby communities of Hammond, Henderson, Millville, Oronoco, Pipestone, and Rapidan also received extensive flooding and damage but were not surveyed for high-water marks. Flood-peak inundation maps and water-surface profiles for the four most severely affected communities were constructed in a geographic information system by combining high-water-mark data with the highest resolution digital elevation model data available. The flood maps and profiles show the extent and height of flooding through the communities and can be used for flood response and recovery efforts by local, county, State, and Federal agencies.

Minnesota↗

Observed and forecast flood-inundation mapping application-A pilot study of an eleven-mile reach of the White River, Indianapolis, Indiana

Near-real-time and forecast flood-inundation mapping products resulted from a pilot study for an 11-mile reach of the White River in Indianapolis. The study was done by the U.S. Geological Survey (USGS), Indiana Silver Jackets hazard mitigation taskforce members, the National Weather Service (NWS), the Polis Center, and Indiana University, in cooperation with the City of Indianapolis, the Indianapolis Museum of Art, the Indiana Department of Homeland Security, and the Indiana Department of Natural Resources, Division of Water. The pilot project showed that it is technically feasible to create a flood-inundation map library by means of a two-dimensional hydraulic model, use a map from the library to quickly complete a moderately detailed local flood-loss estimate, and automatically run the hydraulic model during a flood event to provide the maps and flood-damage information through a Web graphical user interface. A library of static digital flood-inundation maps was created by means of a calibrated two-dimensional hydraulic model. Estimated water-surface elevations were developed for a range of river stages referenced to a USGS streamgage and NWS flood forecast point colocated within the study reach. These maps were made available through the Internet in several formats, including geographic information system, Keyhole Markup Language, and Portable Document Format. A flood-loss estimate was completed for part of the study reach by using one of the flood-inundation maps from the static library. The Federal Emergency Management Agency natural disaster-loss estimation program HAZUS-MH, in conjunction with local building information, was used to complete a level 2 analysis of flood-loss estimation. A Service-Oriented Architecture-based dynamic flood-inundation application was developed and was designed to start automatically during a flood, obtain near real-time and forecast data (from the colocated USGS streamgage and NWS flood forecast point within the study reach), run the two-dimensional hydraulic model, and produce flood-inundation maps. The application used local building data and depth-damage curves to estimate flood losses based on the maps, and it served inundation maps and flood-loss estimates through a Web-based graphical user interface.

Indiana↗

Floods of June 2012 in northeastern Minnesota

During June 19–20, 2012, heavy rainfall, as much as 10 inches locally reported, caused severe flooding across northeastern Minnesota. The floods were exacerbated by wet antecedent conditions from a relatively rainy spring, with May 2012 as one of the wettest Mays on record in Duluth. The June 19–20, 2012, rainfall event set new records in Duluth, including greatest 2-day precipitation with 7.25 inches of rain. The heavy rains fell on three major watersheds: the Mississippi Headwaters; the St. Croix, which drains to the Mississippi River; and Western Lake Superior, which includes the St. Louis River and other tributaries to Lake Superior. Widespread flash and river flooding that resulted from the heavy rainfall caused evacuations of residents, and damages to residences, businesses, and infrastructure. In all, nine counties in northeastern Minnesota were declared Federal disaster areas as a result of the flooding. Peak-of-record streamflows were recorded at 13 U.S. Geological Survey streamgages as a result of the heavy rainfall. Flood-peak gage heights, peak streamflows, and annual exceedance probabilities were tabulated for 35 U.S. Geological Survey streamgages. Flood-peak streamflows in June 2012 had annual exceedance probabilities estimated to be less than 0.002 (0.2 percent; recurrence interval greater than 500 years) for five streamgages, and between 0.002 and 0.01 (1 percent; recurrence interval greater than 100 years) for four streamgages. High-water marks were identified and tabulated for the most severely affected communities of Barnum (Moose Horn River), Carlton (Otter Creek), Duluth Heights neighborhood of Duluth (Miller Creek), Fond du Lac neighborhood of Duluth (St. Louis River), Moose Lake (Moose Horn River and Moosehead Lake), and Thomson (Thomson Reservoir outflow near the St. Louis River). Flood-peak inundation maps and water-surface profiles were produced for these six severely affected communities. The inundation maps were constructed in a geographic information system by combining high-water-mark data with high-resolution digital elevation model data. The flood maps and profiles show the extent and depth of flooding through the communities and can be used for flood response and recovery efforts by local, county, State, and Federal agencies.

Minnesota↗

Analysis and inundation mapping of the April-May 2011 flood at selected locations in northern and eastern Arkansas and southern Missouri

Precipitation that fell from April 19 through May 3, 2011, resulted in widespread flooding across northern and eastern Arkansas and southern Missouri. The first storm produced a total of approximately 16 inches of precipitation over an 8-day period, and the following storms produced as much as 12 inches of precipitation over a 2-day period. Moderate to major flooding occurred quickly along many streams within Arkansas and Missouri (including the Black, Cache, Illinois, St. Francis, and White Rivers) at levels that had not been seen since the historic 1927 floods. The 2011 flood claimed an estimated 21 lives in Arkansas and Missouri, and damage caused by the flooding resulted in a Federal Disaster Declaration for 59 Arkansas counties that received Federal or State assistance. To further the goal of documenting and understanding floods, the U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency, the U.S. Army Corps of Engineers–Little Rock and Memphis Districts, and Arkansas Natural Resources Commission, conducted a study to summarize meteorological and hydrological conditions before the flood; computed flood-peak magnitudes for 39 streamgages; estimated annual exceedance probabilities for 37 of those streamgages; determined the joint probabilities for 11 streamgages paired to the Mississippi River at Helena, Arkansas, which refers to the probability that locations on two paired streams simultaneously experience floods of a magnitude greater than or equal to a given annual exceedance probability; collected high-water marks; constructed flood-peak inundation maps showing maximum flood extent and water depths; and summarized flood damages and effects. For the period of record used in this report, peak-of-record stage occurred at 24 of the 39 streamgages, and peak-of-record streamflow occurred at 13 of the 30 streamgages where streamflow was determined. Annual exceedance probabilities were estimated to be less than 0.5 percent at three streamgages. The joint probability values for streamgages paired with the Mississippi River at Helena, Ark., streamgage indicate a low probability of concurrent flooding with the paired streamgages. The inundation maps show the flood-peak extent and water depth of flooding for two stream reaches on the White River and two on the Black River; the vicinities of the communities of Holly Grove and Cotton Plant, Ark.; a reach of the White River that includes the crossing of Interstate 40 north of De Valls Bluff, Ark.; and the Tailwaters of Beaver Dam near Eureka Springs, Ark., Table Rock Dam near Branson, Mo., and Bull Shoals Dam near Flippin, Ark. The data and inundation maps can be used for flood response, recovery, and planning efforts by Federal, State, and local agencies.

Arkansas;Missouri↗

Evaluation of the expected moments algorithm and a multiple low-outlier test for flood frequency analysis at streamgaging stations in Arizona

Flooding is among the costliest natural disasters in terms of loss of life and property in Arizona, which is why the accurate estimation of flood frequency and magnitude is crucial for proper structural design and accurate floodplain mapping. Current guidelines for flood frequency analysis in the United States are described in Bulletin 17B (B17B), yet since B17B’s publication in 1982 (Interagency Advisory Committee on Water Data, 1982), several improvements have been proposed as updates for future guidelines. Two proposed updates are the Expected Moments Algorithm (EMA) to accommodate historical and censored data, and a generalized multiple Grubbs-Beck (MGB) low-outlier test. The current guidelines use a standard Grubbs-Beck (GB) method to identify low outliers, changing the determination of the moment estimators because B17B uses a conditional probability adjustment to handle low outliers while EMA censors the low outliers. B17B and EMA estimates are identical if no historical information or censored or low outliers are present in the peak-flow data. EMA with MGB (EMA-MGB) test was compared to the standard B17B (B17B-GB) method for flood frequency analysis at 328 streamgaging stations in Arizona. The methods were compared using the relative percent difference (RPD) between annual exceedance probabilities (AEPs), goodness-of-fit assessments, random resampling procedures, and Monte Carlo simulations. The AEPs were calculated and compared using both station skew and weighted skew. Streamgaging stations were classified by U.S. Geological Survey (USGS) National Water Information System (NWIS) qualification codes, used to denote historical and censored peak-flow data, to better understand the effect that nonstandard flood information has on the flood frequency analysis for each method. Streamgaging stations were also grouped according to geographic flood regions and analyzed separately to better understand regional differences caused by physiography and climate. The B17B-GB and EMA-MGB RPD-boxplot results showed that the median RPDs across all streamgaging stations for the 10-, 1-, and 0.2-percent AEPs, computed using station skew, were approximately zero. As the AEP flow estimates decreased (that is, from 10 to 0.2 percent AEP) the variability in the RPDs increased, indicating that the AEP flow estimate was greater for EMA-MGB when compared to B17B-GB. There was only one RPD greater than 100 percent for the 10- and 1-percent AEP estimates, whereas 19 RPDs exceeded 100 percent for the 0.2-percent AEP. At streamgaging stations with low-outlier data, historical peak-flow data, or both, RPDs ranged from −84 to 262 percent for the 0.2-percent AEP flow estimate. When streamgaging stations were separated by the presence of historical peak-flow data (that is, no low outliers or censored peaks) or by low outlier peak-flow data (no historical data), the results showed that RPD variability was greatest for the 0.2-AEP flow estimates, indicating that the treatment of historical and (or) low-outlier data was different between methods and that method differences were most influential when estimating the less probable AEP flows (1, 0.5, and 0.2 percent). When regional skew information was weighted with the station skew, B17B-GB estimates were generally higher than the EMA-MGB estimates for any given AEP. This was related to the different regional skews and mean square error used in the weighting procedure for each flood frequency analysis. The B17B-GB weighted skew analysis used a more positive regional skew determined in USGS Water Supply Paper 2433 (Thomas and others, 1997), while the EMA-MGB analysis used a more negative regional skew with a lower mean square error determined from a Bayesian generalized least squares analysis. Regional groupings of streamgaging stations reflected differences in physiographic and climatic characteristics. Potentially influential low flows (PILFs) were more prevalent in arid regions of the State, and generally AEP flows were larger with EMA-MGB than with B17B-GB for gaging stations with PILFs. In most cases EMA-MGB curves would fit the largest floods more accurately than B17B-GB. In areas of the State with more baseflow, such as along the Mogollon Rim and the White Mountains, streamgaging stations generally had fewer PILFs and more positive skews, causing estimated AEP flows to be larger with B17B-GB than with EMA-MGB. The effect of including regional skew was similar for all regions, and the observed pattern was increasingly greater B17B-GB flows (more negative RPDs) with each decreasing AEP quantile. A variation on a goodness-of-fit test statistic was used to describe each method’s ability to fit the largest floods. The mean absolute percent difference between the measured peak flows and the log-Pearson Type 3 (LP3)-estimated flows, for each method, was averaged over the 90th, 75th, and 50th percentiles of peak-flow data at each site. In most percentile subsets, EMA-MGB on average had smaller differences (1 to 3 percent) between the observed and fitted value, suggesting that the EMA-MGB-LP3 distribution is fitting the observed peak-flow data more precisely than B17B-GB. The smallest EMA-MGB percent differences occurred for the greatest 10 percent (90th percentile) of the peak-flow data. When stations were analyzed by USGS NWIS peak flow qualification code groups, the stations with historical peak flows and no low outliers had average percent differences as high as 11 percent greater for B17B-GB, indicating that EMA-MGB utilized the historical information to fit the largest observed floods more accurately. A resampling procedure was used in which 1,000 random subsamples were drawn, each comprising one-half of the observed data. An LP3 distribution was fit to each subsample using B17B-GB and EMA-MGB methods, and the predicted 1-percent AEP flows were compared to those generated from distributions fit to the entire dataset. With station skew, the two methods were similar in the median percent difference, but with weighted skew EMA-MGB estimates were generally better. At two gages where B17B-GB appeared to perform better, a large number of peak flows were deemed to be PILFs by the MGB test, although they did not appear to depart significantly from the trend of the data (step or dogleg appearance). At two gages where EMA-MGB performed better, the MGB identified several PILFs that were affecting the fitted distribution of the B17B-GB method. Monte Carlo simulations were run for the LP3 distribution using different skews and with different assumptions about the expected number of historical peaks. The primary benefit of running Monte Carlo simulations is that the underlying distribution statistics are known, meaning that the true 1-percent AEP is known. The results showed that EMA-MGB performed as well or better in situations where the LP3 distribution had a zero or positive skew and historical information. When the skew for the LP3 distribution was negative, EMA-MGB performed significantly better than B17B-GB and EMA-MGB estimates were less biased by more closely estimating the true 1-percent AEP for 1, 2, and 10 historical flood scenarios.

Arizona↗

Methods for estimating magnitude and frequency of floods in Arizona, developed with unregulated and rural peak-flow data through water year 2010

Flooding is among the worst natural disasters responsible for loss of life and property in Arizona, underscoring the importance of accurate estimation of flood magnitude for proper structural design and floodplain mapping. Twenty-four years of additional peak-flow data have been recorded since the last comprehensive regional flood frequency analysis conducted in Arizona. Periodically, flood frequency estimates and regional regression equations must be revised to maintain the accurate estimation of flood frequency and magnitude. Annual peak-flow data collected through water year 2010 were compiled from 448 unregulated streamflow-gaging stations, hereafter referred to as streamgages, in Arizona having a minimum of 10 years of record. Flood frequency estimates were first computed with station (or at-site) skew using the Expected Moments Algorithm with a multiple Grubbs-Beck test to identify multiple potentially influential low flows to fit a Pearson Type III distribution. Next, a multiple step Bayesian least-squares-regression approach was used to determine a new statewide regional skew of &minus;0.09. No basin characteristics analyzed were statistically significant in explaining the variation in skew and as a result, the constant model was chosen as the best regional skew model for the Arizona study area. The mean square error used in Bulletin 17B (B17B) of the Interagency Advisory Committee on Water Data is used to describe the precision of the regional skew. The constant model had a mean square error equal to 0.08, which corresponds to an effective record length of 85 years. This is a marked improvement over a previous Arizona regional skew analysis, with a reported mean square error of 0.31, for a corresponding effective record length of around 17 years. Thus the new regional model had almost five times the information content (as measured by effective record length) of that calculated in USGS Water Supply Paper 2433, published in 1997, or the value of 0.302 reported in the B17B generalized skew map. The flood frequency estimates were recalculated using a weighted skew of the station and regional skew. Station flood frequency estimates for each streamgage are presented for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities. Geographical information systems were used to compute basin characteristic information for each streamgage for the purpose of developing regional equations to estimate flood statistics at ungaged basins. Five hydrologic flood regions in Arizona were defined in a multivariate regionalization process based on mean basin elevation, mean annual precipitation, and soil permeability. A regional generalized least-squares-regression analysis was used to develop five sets of equations from 344 nonredundant streamgages, corresponding to five regions, for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities at ungaged basins in Arizona. The regression equations developed for these five regions were based on one or more of the statistically significant explanatory variables: drainage area, mean basin elevation, and mean annual precipitation. Average standard errors of prediction for the regression regions for the five regions ranged from 27 to 122 percent and the pseudo-coefficients of determination (pseudo-R 2 ), a measure of the proportion of peak-flow variation that is explained by the basin characteristics, ranged from 68 to 98 percent. Regression equations for Central Highlands (region 4) had the lowest model error and the greatest pseudo-R 2 metrics. The equations for Colorado Plateau (region 2) regression equations generally had greater model error and lower pseudo-R 2 metrics. The improvement of regional regression equation model error and pseudo-R 2 metrics was related to higher numbers of streamgages, longer period of record, and even spatial coverage within a region. The regional regression equations were integrated into the U.S. Geological Survey&rsquo;s StreamStats program. The StreamStats program is a national map-based web application that allows the public to easily access published flood frequency and basin characteristic statistics. The interactive web application allows a user to select a point within a watershed (gaged or ungaged) and retrieve flood-frequency estimates derived from the current regional regression equations and geographic information system data within the selected basin. StreamStats provides users with an efficient and accurate means for retrieving the most up to date flood frequency and basin characteristic data. StreamStats is intended to provide consistent statistics, minimize user error, and reduce the need for large datasets and costly geographic information system software.

Arizona↗