Geology topics

Christopher F. Smith

Publications and source records attributed to Christopher F. Smith.

6 recordsLinked to original sources

USGS2026

Loss and transformation of coastal wetlands due to global change in the conterminous United States: Past, present, and future

Coastal wetlands are being transformed by global change, impacting the ecological and societal benefits provided by these ecosystems. Synthesizing knowledge of historical and expected future transformations in coastal wetlands can help inform forward-looking planning and stewardship efforts. Here, we review anticipated future ecological transformations in coastal wetlands of the conterminous United States and contrast them with past transformations. We examine trends at the national scale but focus in detail on the following six wetland-rich regions: (1) Everglades, (2) Mississippi River delta, (3) Chesapeake Bay, (4) San Francisco Estuary, (5) Puget Sound, and (6) Great Lakes. This review is among the first to integrate and compare coastal wetland transformations in the Great Lakes with their oceanic counterparts. Between 1850 and 1970, wetland losses across the nation were high because coastal wetlands were viewed as flooded wastelands needing to be drained, filled, or excavated to make room for other land uses. Over the last 50 years, growing public and scientific appreciation of the ecological and societal benefits provided by coastal wetlands has fostered tremendous gains in wetland restoration and legal protection. Looking to the future, climate change and accelerated sea-level rise have become critical threats to coastal wetlands and are emerging as major drivers of ecological loss and transformation. This review synthesizes regional knowledge regarding past, present, and future changes to help coastal scientists, environmental managers, and the public better anticipate and prepare for future coastal wetland transformations due to climate change, accelerated sea-level rise, land-use change, and other aspects of global change.

conterminous United States↗

USGS2025

An expert elicitation to inform coastal management decision-making for mitigating future hazards

A scientific expert elicitation was conducted to address the feasibility of restoring coastal environments in response to future hazards to best meet management objectives. Subject matter experts produced probabilistic estimates of coastal change metrics used to evaluate decision objectives and alternatives informed by a stakeholder advisory group. Changes in salt marsh extents, storm surge flooding and barrier island morphology by the year 2050 were estimated for three scenarios of management actions (no action, interior headland restoration, beach and dune nourishment), while also considering the effects of future sea level rise (SLR). Collectively the participants were confident in their expectations of increased storm surge flooding with SLR, regardless of management interventions. Estimates of marsh response had large uncertainty, but experts generally hypothesized that marsh area would decrease with increasing SLR if no action was taken, especially in areas already experiencing marsh deterioration. There was agreement that dune heights and barrier island widths would decrease with SLR if no action was taken. Experts felt that beach and dune nourishment may reduce the amount of erosion under future SLR. All experts recognized the dynamic effects of SLR and feedback between bio-geo-physical processes that govern coastal systems. Participants agreed that size and location of management actions were important factors for influencing the coastal response. Expert elicitation is novel in the context of coastal management decision making and can be a useful tool for informing future scientific needs and providing rapid results to end users to inform reallocation of resources surrounding research and application.

Alabama, Mississippi↗

USGS2015

Continuous slope-area discharge records in Maricopa County, Arizona, 2004–2012

Continuous slope-area (CSA) streamgages have been developed and implemented by the U.S. Geological Survey (USGS) to enable the recording of discharge hydrographs in areas where direct discharge measurements cannot be made. The flashy nature of streamflow in parts of the arid Southwest and remote location of many sites make discharge measurements difficult or impossible to obtain. Consequently, available discharge measurements may be insufficient to develop accurate rating curves, which relate discharge to continuously recorded stage measured at standard streamgages. Nine CSA streamgages have been installed in Maricopa County, Arizona, since 2004 in cooperation with the Flood Control District of Maricopa County. This report presents the data and analysis of computed discharges from those streamgages, along with descriptions of the streamgage site and stream properties. Analyses of sources of errors and the impact stage data errors have on calculated discharge time series are considered, along with issues in data reduction. Steeper, longer stream reaches are generally less sensitive to measurement error. Other issues considered are pressure transducer drawdown, capture of flood peaks with discrete stage data, selection of stage record for development of rating curves, and minimum stages for the calculation of discharge.

Arizona↗

USGS2012

Use of the continuous slope-area method to estimate runoff in a network of ephemeral channels, southeast Arizona, USA

The continuous slope-area (CSA) method is an innovative gaging method for indirect computation of complete-event discharge hydrographs that can be applied when direct measurement methods are unsafe, impractical, or impossible to apply. This paper reports on use of the method to produce event-specific discharge hydrographs in a network of sand-bedded ephemeral stream channels in southeast Arizona, USA, for water year 2008. The method provided satisfactory discharge estimates for flows that span channel banks, and for moderate to large flows, with about 10–16% uncertainty, respectively for total flow volume and peak flow, as compared to results obtained with an alternate method. Our results also suggest that the CSA method may be useful for estimating runoff of small flows, and during recessions, but with increased uncertainty.

Arizona↗

USGS2010

The continuous slope-area method for computing event hydrographs

The continuous slope-area (CSA) method expands the slope-area method of computing peak discharge to a complete flow event. Continuously recording pressure transducers installed at three or more cross sections provide water-surface slopes and stage during an event that can be used with cross-section surveys and estimates of channel roughness to compute a continuous discharge hydrograph. The CSA method has been made feasible by the availability of low-cost recording pressure transducers that provide a continuous record of stage. The CSA method was implemented on the Babocomari River in Arizona in 2002 to monitor streamflow in the channel reach by installing eight pressure transducers in four cross sections within the reach. Continuous discharge hydrographs were constructed from five streamflow events during 2002-2006. Results from this study indicate that the CSA method can be used to obtain continuous hydrographs and rating curves can be generated from streamflow events.

Scientific Investigations Report↗

USGS1998

Statistical summaries of streamflow data and characteristics of drainage basins for selected streamflow-gaging stations in Arizona through water year 1996

Statistical summaries of streamflow data are given for 142 unregulated or partly regulated continuous-record streamflow-gaging stations and 178 peak-flow partial-record stations in Arizona through water year 1996. Streamflow statistics were generated for stations with a minimum period of record of 10 years. Summaries for continuous-record stations include: (1) station description, (2) statistics of mean monthly and annual discharges, (3) magnitude and probability of annual peak discharge, (4) magnitude and probability of annual low and high flow, (5) mean daily flow duration, and (6) basin and climatic characteristics. Statistical summaries for peak-flow partial-record stations include: (1) station description, (2) magnitude and probability of annual peak discharge, and (3) basin and climatic characteristics.

Arizona↗