Geological Survey Streamgages Research Articles

Updating estimates of low-streamflow statistics to account for possible trends

ABSTRACT Accurate estimators of streamflow statistics are critical to the design, planning, and management of water resources. Given increasing evidence of trends in low-streamflow, new approaches to estimating low-streamflow statistics are needed. Here we investigate simple approaches to select a recent subset of the low-flow record to update the commonly used statistic of 7Q10, the annual minimum 7-day streamflow exceeded in 9 out of 10 years on average. Informed by low-streamflow records at 174 US Geological Survey streamgages, Monte Carlo simulation experiments evaluate competing approaches. We find that a strategy which estimates 7Q10 using the most recent 30 years of record when a trend is detected, reduces error and bias in 7Q10 estimators compared to use of the full record. This simple rule-based approach has potential as the basis for a framework for updating frequency-based statistics in the context of possible trends.

Estimation of Base Flow by Optimal Hydrograph Separation for the Conterminous United States and Implications for National-Extent Hydrologic Models

Optimal hydrograph separation (OHS) uses a two-parameter recursive digital filter that applies specific conductance mass-balance constraints to estimate the base flow contribution to total streamflow at stream gages where discharge and specific conductance are measured. OHS was applied to U.S. Geological Survey (USGS) stream gages across the conterminous United States to examine the range/distribution of base flow inputs and the utility of this method to build a hydrologic model calibration dataset. OHS models with acceptable goodness-of-fit criteria were insensitive to drainage area, stream density, watershed slope, elevation, agricultural or perennial snow/ice land cover, average annual precipitation, runoff, or evapotranspiration, implying that OHS results are a viable calibration dataset applicable in diverse watersheds. OHS-estimated base flow contribution was compared to base flow-like model components from the USGS National Hydrologic Model Infrastructure run with the Precipitation-Runoff Modeling System (NHM-PRMS). The NHM-PRMS variable gwres_flow is most conceptually like a base flow component of streamflow but the gwres_flow contribution to total streamflow is generally smaller than the OHS-estimated base flow contribution. The NHM-PRMS variable slow_flow, added to gwres_flow, produced similar or greater estimates of base flow contributions to total streamflow than the OHS-estimated base flow contribution but was dependent on the total flow magnitude.

Adding invasive species biosurveillance to the U.S. Geological Survey streamgage network

AbstractThe costs of invasive species in the United States alone are estimated to exceed US$100 billion per year, so a critical tactic in minimizing the costs of invasive species is the development of effective, early‐detection systems. To this end, we evaluated the efficacy of adding environmental (e)DNA surveillance to the U.S. Geological Survey (USGS) streamgage network, which consists of >8200 streamgages nationwide systemically visited by USGS hydrologic technicians. Incorporating strategic eDNA sample collection during routine streamgage visits could provide early‐detection surveillance of aquatic invasive species with minimal additional cost. For this evaluation, USGS hydrologic technicians collected monthly eDNA water samples, May–September 2018, from streamgages downstream of reservoirs in the Columbia River Basin thought to be vulnerable to invasive dreissenid mussel (Dreissenidae spp.) establishment. We tested water samples for dreissenid mussel DNA and also for kokanee (Oncorhynchus nerka) and yellow perch (Perca flavescens) DNA; the two fishes were used to assess if streamgages are adequately located to provide early‐detection eDNA surveillance of taxa known to be present in upstream reservoirs. No Columbia River Basin streamgage samples met our criteria for being scored as positive for dreissenid DNA. We did detect kokanee and yellow perch DNA at all streamgages downstream of reservoirs where these species are known to occur. Field collection, laboratory analyses, and personnel time required for collection of four eDNA samples at a streamgage site cost US$500–US$600 (net). Given these results, incorporating eDNA biosurveillance into routine streamgage visits might decrease costs associated with an invasion since early detection maximizes the potential for eradication, containment, and mitigation.

Assessing Retrospective National Water Model Streamflow with Respect to Droughts and Low Flows in the Colorado River Basin

AbstractStreamflow monitoring in the Colorado River Basin (CRB) is essential to ensure diverse needs are met, especially during periods of drought or low flow. Existing stream gage networks, however, provide a limited record of past and current streamflow. Modeled streamflow products with more complete spatial and temporal coverage (including the National Water Model [NWM]), have primarily focused on flooding, rather than sustained drought or low flow conditions. Objectives of this study are to (1) evaluate historical performance of the NWM streamflow estimates (particularly with respect to droughts and seasonal low flows) and (2) identify characteristics relevant to model inputs and suitability for future applications. Comparisons of retrospective flows from the NWM to observed flows from the United States Geological Survey stream gage network over 22 years in the CRB reveal a tendency for underestimating low flow frequency, locations with low flows, and the number of years with low flows. We found model performance to be more accurate for the Upper CRB and at sites with higher precipitation, snow percent, baseflow index, and elevations. Underestimation of low flows and variable model performance has important implications for future applications: inaccurate evaluations of historical low flows and droughts, and less reliable performance outside of specific watershed/stream conditions. This highlights characteristics on which to focus future model development efforts.

Downstream‐Propagating Channel Responses to Decadal‐Scale Climate Variability in a Glaciated River Basin

AbstractRegional climate is an important control on the rate of coarse sediment mobilization and transport in alpine river systems. Changes in climate are then expected to cause a cascade of geomorphic responses, including adjustments in downstream channel morphology. However, the mechanics and sensitivity of channel response to short‐term climate variability remain poorly documented. In the Nooksack River, which drains a glaciated stratovolcano in Washington State, bed elevation changes were inferred from shifting stage‐discharge relations at seven U.S Geological Survey stream gages. Decadal‐scale elevation trends can be explained as a downstream‐propagating channel response to regional climate variability, where periods of persistent warm, dry (cool and wet) conditions corresponded to periods of aggradation (incision). The channel elevation response propagated downstream at a rate of 1 to 4 km per year; propagation rate scaled closely with channel slope. Historical trends in glacier extent and flood intensity both show some potential to explain climate‐sediment linkages, though assessing causation is complicated by the shared climate signal in both records. Results show the influence of the Pacific Decadal Oscillation, with relatively high coarse sediment yields prior to 1950 and since 1980, and notably lower sediment yields from 1950 to 1980. Measured sediment yields from nearby glaciated basins corroborate this history, suggesting a regional consistency to these climate‐sediment linkages. These results document consistent relations between climate, sediment supply, and downstream channel response at the basin scale, with channel responses propagating downstream over periods of decades with little apparent attenuation.

Mapped Hydroclimatology of Evapotranspiration and Drainage Runoff Using SMAP Brightness Temperature Observations and Precipitation Information

AbstractThe partitioning of incident precipitation into evapotranspiration, runoff, drainage, storage change, and hydrologic fluxes depends on the soil moisture state. With the availability of global remotely sensed soil moisture fields, the functional dependence of each flux on soil moisture may be identifiable. In this study we develop an observation‐driven approach to map key hydroclimatology fields using remotely sensed soil moisture and gauge‐based precipitation data only. National Aeronautics and Space Administration's Soil Moisture Active Passive (SMAP) low‐frequency microwave brightness temperature observations and precipitation fields, from the National Centers for Environmental Prediction, are the sole inputs into an adjoint‐state variational estimation framework. Furthermore, the proposed methodology does not rely on micrometeorological information, or land surface models. The approach is flexible by design so that almost any partitioning pattern can result from estimation and corresponding evapotranspiration and drainage fields can be quantified. Three‐year averaged summer season evapotranspiration estimates are compared with available vapor flux at in situ AmeriFlux eddy‐covariance sites. Basin‐averaged drainage over major U.S. hydrologic units is also compared with U.S. Geological Survey streamgages measurements. The remote sensing‐based estimated hydroclimate fields explain about 70% of the variance in the in situ measurements. This exploratory study adds to the body of evidence emerging in literature that a significant amount of hydrologic information is encoded in the dynamic fields of remotely sensed soil moisture. Observation‐driven hydroclimate data fields that are independent of land surface models can provide valuable insights into the state of the water cycle and guide future development of land surface models.

Quantifying model uncertainty using Bayesian multi-model ensembles

Watershed models are essential tools to understand, quantify, and predict hydrologic processes and water quality responses from scales ranging from field to large river basins. However, the reliability of watershed models in a management context depends largely on inherent uncertainties in model predictions. The objective of this study is to quantify prediction uncertainty for flow, sediment, total nitrogen (TN), and total phosphorus (TP) resulting from model structure. We do this using using three process-based models: the Soil and Water Assessment Tool-Variable Source Area model (SWAT-VSA), the standard Soil and Water Assessment Tool (SWAT-ST), and the Chesapeake Bay Program’s Phase 6 Watershed Model (CBP-Model). We initialize each of the models using meteorological, soil, and land use data, and analyze outputs of flow, sediment, TN, and TP fluxes at the U.S. Geological Survey stream gauge at the downstream end of the Susquehanna River Basin in Conowingo, Maryland. Using these three models, we develop and compare two types of Bayesian models, a Bayesian Generalized (Non-) Linear Multilevel Model (BGMM), and a Bayesian Model Averaging (BMA) for flow, sediment, TN, and TP and 95% credible intervals. We compare the Bayesian models results against the individual model results, and straight model averaging (SMA) using a split time period analysis to assess their predictive strengths. Both Bayesian models provided substantially better predictions than the individual process-based models, and estimates of prediction uncertainty, which can enhance decision-making and improve watershed management by providing a risk based assessment of outcomes.

Geomorphic Responses to Extreme Rainfall, Catastrophic Flooding, and Dam Failures across an Urban to Rural Landscape

The extreme rainfall of October 2015 in South Carolina generated numerous dam failures and spawned the flood of record at most U.S. Geological Survey stream gauges. Detailed field sampling and systematic image analysis are used to document the immediate and sustained geomorphic adjustments at four failed dams within the urbanized Gills Creek watershed. That urban focus is augmented with a similar analysis at five failed dams in more rural settings where less urban infrastructure exists. We also document the magnitude and type of geomorphic adjustments throughout the Gills Creek watershed unrelated to dam failures. Despite the extreme rainfall and associated flooding, the geomorphic effects were limited and localized, manifesting primarily at dam failures but not progressing significantly downstream, especially along Gills Creek, where the combination of intact dams, frequent urban roughness elements, thick floodplain vegetation, and numerous wetlands explains the lack of significant morphologic adjustments or major deposition. Dam failures in rural settings showed greater overbank deposition but the geomorphic effects were still limited to dam proximal locations because of the thick vegetal cover below the dam. Because these dams in rural and urban settings were constructed to maximize waterfront property, low gradient sites were selected; therefore, the geomorphic effects were unlike planned dam removals where massive headcutting, knickpoint migration, and sediment evacuation tend to occur. The most significant effect of the dam failures was the shift from an initial braided channel to a single thread channel within the emptied reservoirs, which occurred quickly, often within the first few months.

Strange Floods: The Upper Tail of Flood Peaks in the United States

AbstractWe examine the upper tail of flood peak distributions through analyses of annual peak observations from more than 8,000 U.S. Geological Survey (USGS) stream gaging stations and through hydrometeorological analyses of the storms that produce the most extreme floods. We focus on the distribution of the upper tail ratio, which is defined as the peak discharge for the flood of record at a stream gaging station divided by the sample 10‐year flood magnitude. The 14 June 1903 Heppner storm, which produced an upper tail ratio of 200, was the product of a hailstorm that formed along the Blue Mountains in eastern Oregon, a region dominated by snowmelt flooding. A striking contrast between record flood peaks and the larger distribution of annual flood peaks in the United States is in the seasonality of flood occurrence, with record floods reflecting a much stronger contribution from warm season thunderstorm systems. Mountainous terrain and intense convective rainfall are important elements of the geography and hydrometeorology of extreme upper tail ratio flood peaks. The distribution of upper tail ratio values for USGS stream gaging stations does not depend on basin area, a result which is consistent with scaling results based on extreme value theory. Downscaling simulations with the Weather Research and Forecasting model are used to examine the storm environment of the 1903 Heppner storm, along with two other record flood peaks near the Blue Mountains of eastern Oregon from the USGS miscellaneous flood record, the July 1956 Meyers Canyon flood and the July 1965 Lane Canyon flood.

Using United States Geological Survey stream gages to predict flow and temperature conditions to maintain freshwater mussel habitat

AbstractHabitat conditions necessary to support freshwater mussels can be difficult to characterize and predict, particularly for rare or endangered species such as the federally endangered dwarf wedgemussel, Alasmidonta heterodon. In this study, we evaluate flow and temperature conditions in three areas of the mainstem Delaware River known to consistently support A. heterodon, and we develop predictive models using the U.S. Geological Survey (USGS) stream gages and thermal stations in order to identify conditions under which habitat alteration could threaten the species. Flow and temperature prediction models based on nearby existing USGS gage and thermal stations were predictive for all three sites. Both discharge prediction and water depth profile models indicate one location (Site 3) was the most vulnerable to low‐flow conditions as it requires the highest discharge rate (26.3 cms) at the USGS Callicoon gage to maintain both the full wetted perimeter (Pfull) and minimal wetted perimeter (Pmin) and prevent occlusion of areas that contain A. heterodon. Flow management targets aimed at protecting Site 3 should also protect Sites 1 and 2. Although analyses indicated significant benthic habitat available in all three sites even under low discharge rates, specific mussel locations could be vulnerable to dewatering and thermal stress if only Pmin values were maintained. Results indicate the magnitude of site temperature deviations from thermal stations varied by site and river temperature. In general, our results suggest that existing temperature and stream gage infrastructure may be used predictively to evaluate the effects of different flow targets on mainstem Delaware River A. heterodon habitat.

Contribution of eastern North Pacific tropical cyclones and their remnants on flooding in the western United States

Recent studies have focused on identifying the spatial coverage of heavy rainfall associated with tropical cyclones (TCs) and their remnants (TC‐events) throughout the southwestern United States from eastern North Pacific storms. Yet little is known about the larger spatial contribution of these storms among extreme floods over the western United States. This paper examines the spatial and fractional contribution of 103 TC‐events among annual maximum streamflow at 1,429 long‐term U.S. Geological Survey (USGS) streamgages with at least 30 years of daily discharge data over the 1958–2010 water years. The highest fractional contributions to annual daily maxima by these storms (~5–14%) are found in southern California, Arizona, southernmost Nevada and Utah, southern and western New Mexico, central Colorado, and Texas. While nearly 32% of the streamgages have at least one annual maximum that was generated by a TC‐event, TC‐events play a limited role in contributing to the upper tail of the flood peak distribution across the western United States.

Riverine discharges to Chesapeake Bay: Analysis of long-term (1927–2014) records and implications for future flows in the Chesapeake Bay basin

The Chesapeake Bay (CB) basin is under a total maximum daily load (TMDL) mandate to reduce nitrogen, phosphorus, and sediment loads to the bay. Identifying shifts in the hydro-climatic regime may help explain observed trends in water quality. To identify potential shifts, hydrologic data (1927–2014) for 27 watersheds in the CB basin were analyzed to determine the relationships among long-term precipitation and stream discharge trends. The amount, frequency, and intensity of precipitation increased from 1910 to 1996 in the eastern U.S., with the observed increases greater in the northeastern U.S. than the southeastern U.S. The CB watershed spans the north-to-south gradient in precipitation increases, and hydrologic differences have been observed in watersheds north relative to watersheds south of the Pennsylvania—Maryland (PA-MD) border. Time series of monthly mean precipitation data specific to each of 27 watersheds were derived from the Precipitation-elevation Regression on Independent Slopes Model (PRISM) dataset, and monthly mean stream-discharge data were obtained from U.S. Geological Survey streamgage records. All annual precipitation trend slopes in the 18 watersheds north of the PA-MD border were greater than or equal to those of the nine south of that border. The magnitude of the trend slopes for 1927–2014 in both precipitation and discharge decreased in a north-to-south pattern. Distributions of the monthly precipitation and discharge datasets were assembled into percentiles for each year for each watershed. Multivariate correlation of precipitation and discharge within percentiles among the groups of northern and southern watersheds indicated only weak associations. Regional-scale average behaviors of trends in the distribution of precipitation and discharge annual percentiles differed between the northern and southern watersheds. In general, the linkage between precipitation and discharge was weak, with the linkage weaker in the northern watersheds compared to those in the south. On the basis of simple linear regression, 26 of the 27 watersheds are projected to have higher annual mean discharge in 2025, the target date for implementation of the TMDL for the CB basin.

Body-shape variation ofAcroneuria lycorias(Plecoptera∶Perlidae) nymphs across magnitude and frequency stream flows

AbstractMorphological variation across environmental gradients can indicate an organismal phenotypic response to the surrounding environment. The interaction of body shape and water movement creates physical forces that can affect the ecology and evolution of benthic organisms in stream systems. Magnitude and frequency components of flow regimes have been linked to morphological variation in body shape of fish and macrophytes, but very few attempts have been made to evaluate similar relationships in stream insects. The aim of our study was to evaluate body-shape variation in large nymphs of an insect species and to test for a correlation with natural streamflow fluctuations in a regional geographic space. We sampled Acroneuria lycorias (Plecoptera∶Perlidae) populations at 9 stream sites (8 systems) with an associated US Geological Survey stream gage. We calculated ecological flow statistics from daily discharge data, and we used 2-dimensional geometric morphometrics to describe variation in A. lycorias bo...

Coupling fine particle and bedload transport in gravel-bedded streams

Fine particles in the silt- and clay-size range are important determinants of surface water quality. Since fine particle loading rates are not unique functions of stream discharge this limits the utility of the available models for water quality assessment. Data from 38 minimally developed watersheds within the United States Geological Survey stream gauging network in California, USA reveal three lines of evidence that fine particle release is coupled with bedload transport. First, there is a transition in fine particle loading rate as a function of discharge for gravel-bedded sediments that does not appear when the sediment bed is composed of sand, cobbles, boulders, or bedrock. Second, the discharge at the transition in the loading rate is correlated with the initiation of gravel mobilization. Third, high frequency particle concentration and discharge data are dominated by clockwise hysteresis where rising limb discharges generally have higher concentrations than falling limb discharges. These three observations across multiple watersheds lead to a conceptual model that fine particles accumulate within the sediment bed at discharges less than the transition and then the gravel bed fluidizes with fine particle release at discharges above the transition discharge. While these observations were individually recognized in the literature, this analysis provides a consistent conceptual model based on the coupling of fine particle dynamics with filtration at low discharges and gravel bed fluidization at higher discharges.

Streamflow alteration and habitat ramifications for a threatened fish species in the Central United States

AbstractIn the Central United States, the Arkansas darter (Etheostoma cragini) is listed as a threatened fish species by the State of Kansas. Survival of the darter is threatened by loss of habitat caused by changing streamflow conditions, in particular flow depletion. Future management of darter populations and habitats requires an understanding of streamflow conditions and how those conditions may have changed over time in response to natural and anthropogenic factors. In Kansas, streamflow alteration was assessed at 9 U.S. Geological Survey streamgages in 6 priority basins with no pronounced long‐term trends in precipitation. The assessment was based on a comparison of observed (O) and predicted expected (E) reference conditions for 29 flow metrics. The O/E results indicated a likely or possible diminished flow condition in 2 basins; the primary cause of which is groundwater‐level declines resulting from groundwater pumping for irrigated agriculture. In these 2 basins, habitat characteristics adversely affected by flow depletion may include stream connectivity, pools, and water temperature. The other 4 basins were minimally affected, or unaffected, by flow depletion and therefore may provide the best opportunity for preservation of darter habitat. Through the O/E analysis, anthropogenic streamflow alteration was quantified and the results will enable better‐informed decisions pertaining to the future management of darters in Kansas.

Use of sacrificial embankments to minimize bridge damage from scour during extreme flow events

The leading cause of bridge failure has often been identified as bridge scour, which is generally defined as the erosion or removal of streambed and/or bank material around bridge foundations due to flowing water. These scour critical bridges are particularly vulnerable during extreme flood events, and pose a major risk to human life, transportation infrastructure, and economic sustainability. Retrofitting the thousands of undersized and scour critical bridges to more rigorous standards is prohibitively expensive requiring effective yet economical countermeasures. This research tested the efficacy of using approach embankments as intentional sacrificial “fuses” to protect the bridge integrity and minimize damage during large flow events by allowing the streams to access their natural floodplain and reduce channel velocities. This countermeasure concept was evaluated using the Hydrologic Engineering Center’s River Analysis System models. Steady flow models were developed for three specific bridges on two river reaches. Streamflow return period estimators for both river reaches were developed using Bayesian analysis and available United States Geological Survey stream gauge data to evaluate sacrificial embankments under non-stationary climatic conditions. The use of sacrificial embankments was determined to be a cost-effective scour mitigation strategy for bridges with suboptimal hydraulic capacity and unknown or shallow foundations. Additional benefits of sacrificial embankments include reductions in upstream flood stage and velocity.

The Historic South Carolina Rainfall and Major Floods of October 1-5, 2015

A record setting and historic rainfall event occurred October 1-5, 2015, producing widespread and significant flooding across much of South Carolina. The rainfall resulted from several atmospheric and hydrometeorological factors. The record rainfall triggered flash floods and riverine flooding that resulted in emergency evacuations, travel disruptions, personal property damage, business losses, bridge collapses, dam failures and tragic loss of life. Precipitation records were broken from the midlands to the coast, with totals ranging from 10 to over 26 inches of rain. Sixteen National Weather Service Cooperative Weather Stations set new 24-hour rainfall records for October. The amount of rainfall during the event at various locations and for various durations (6-, 24-, 48-, 72-, 96- hours) had a statistical probability of occurrence of 0.1% or 1 in 1,000 chance of happening in any given year, according to the National Oceanic and Atmospheric Administration (NOAA) Atlas 14. Streams and creeks swelled out of their banks with at least 17 U.S. Geological Survey (USGS) stream gages reaching record peaks. The event was the worst flooding most residents had ever experienced. This report will provide a synoptic and chronological overview of how the historic rain and flooding unfolded with documentation of the meteorological and hydrological records. A comprehensive interactive journal of the event is available on-line at http://www.dnr.sc.gov/flood2015.

Continental U.S. streamflow trends from 1940 to 2009 and their relationships with watershed spatial characteristics

AbstractChanges in streamflow are an important area of ongoing research in the hydrologic sciences. To better understand spatial patterns in past changes in streamflow, we examined relationships between watershed‐scale spatial characteristics and trends in streamflow. Trends in streamflow were identified by analyzing mean daily flow observations between 1940 and 2009 from 967 U.S. Geological Survey stream gages. Results indicated that streamflow across the continental U.S., as a whole, increased while becoming less extreme between 1940 and 2009. However, substantial departures from the continental U.S. (CONUS) scale pattern occurred at the regional scale, including increased annual maxima, decreased annual minima, overall drying trends, and changes in streamflow variability. A subset of watersheds belonging to a reference data set exhibited significantly smaller trend magnitudes than those observed in nonreference watersheds. Boosted regression tree models were applied to examine the influence of watershed characteristics on streamflow trend magnitudes at both the CONUS and regional scale. Geographic location was found to be of particular importance at the CONUS scale while local variability in hydroclimate and topography tended to have a strong influence on regional‐scale patterns in streamflow trends. This methodology facilitates detailed, data‐driven analyses of how the characteristics of individual watersheds interact with large‐scale hydroclimate forces to influence how changes in streamflow manifest.

New streams and springs after the 2014 Mw6.0 South Napa earthquake.

Many streams and springs, which were dry or nearly dry before the 2014 Mw6.0 South Napa earthquake, started to flow after the earthquake. A United States Geological Survey stream gauge also registered a coseismic increase in discharge. Public interest was heightened by a state of extreme drought in California. Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin. Following the earthquake we repeatedly surveyed the new flows, collecting data to test hypotheses about their origin. We show that the new flows originated from groundwater in nearby mountains released by the earthquake. The estimated total amount of new water is ∼106 m3, about 1/40 of the annual water use in the Napa–Sonoma area. Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

Exploring storage and runoff generation processes for urban flooding through a physically based watershed model

AbstractA physically based model of the 14 km2 Dead Run watershed in Baltimore County, MD was created to test the impacts of detention basin storage and soil storage on the hydrologic response of a small urban watershed during flood events. The Dead Run model was created using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) algorithms and validated using U.S. Geological Survey stream gaging observations for the Dead Run watershed and 5 subbasins over the largest 21 warm season flood events during 2008–2012. Removal of the model detention basins resulted in a median peak discharge increase of 11% and a detention efficiency of 0.5, which was defined as the percent decrease in peak discharge divided by percent detention controlled area. Detention efficiencies generally decreased with increasing basin size. We tested the efficiency of detention basin networks by focusing on the “drainage network order,” akin to the stream order but including storm drains, streams, and culverts. The detention efficiency increased dramatically between first‐order detention and second‐order detention but was similar for second and third‐order detention scenarios. Removal of the soil compacted layer, a common feature in urban soils, resulted in a 7% decrease in flood peak discharges. This decrease was statistically similar to the flood peak decrease caused by existing detention. Current soil storage within the Dead Run watershed decreased flood peak discharges by a median of 60%. Numerical experiment results suggested that detention basin storage and increased soil storage have the potential to substantially decrease flood peak discharges.