Prepared in cooperation with the Department of Transportation

Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

16 631.5

River stage 9 2

631.0 9 1 14 Channel bed D V 630.5 N G ZERO GAGE 12 E V E O

V 630.0 B O A B

A 10 629.5 E T F E T F N I

N 8 629.0 I

N , O N , O T I

628.5 A T I 6 A E V

E V 628.0 4 627.5 2 627.0 CHANNEL-BED E L RIVER STAGE E L 0 626.5 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 AUGUST SEPTEMBER 2007 2007

Scientific Investigations Report 2009–5254

U.S. Department of the Interior U.S. Geological Survey Cover photograph. River channel-bed monitor installation and channel-bed elevation at the downstream side of the upstream column of pier 4 and river stage from August 21 through September 9, 2007, for the Chariton River near Prairie Hill, Missouri (structure L-344). Photograph by Paul H. Rydlund, Jr., U.S. Geological Survey. Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

By Paul H. Rydlund, Jr.

Prepared in cooperation with the Missouri Department of Transportation

Scientific Investigations Report 2009–5254

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2009

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Suggested citation: Rydlund, P.H., Jr., 2009, Real-time river channel-bed monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09: U.S. Geological Survey Scientific Investigations Report 2009–5254, 27 p.

.

ISBN 978–1–4113–2634–7 iii

Contents

Abstract ...... 1 Introduction...... 1 Purpose and Scope...... 4 Description of River Channel-Bed Monitors...... 4 River Channel-Bed Monitor Installation and Data Collection...... 4 Chariton River near Prairie Hill (Structure L-344)...... 4 Chariton River at Novinger (Structure L-534)...... 7 at Mehlville (Structures A-1850 and A-4936)...... 7 River Channel-Bed Monitor Results...... 11 Chariton River near Prairie Hill (Structure L-344)...... 11 Chariton River at Novinger (Structure L-534)...... 13 Mississippi River at Mehlville (Structures A-1850 and A-4936)...... 18 River Channel-Bed Monitor Uncertainty and Limitations...... 18 Summary and Conclusions...... 26 References Cited...... 27

Figures

1. Map showing location of river channel-bed monitors in Missouri...... 2 2. Internal configuration, installation, and data dissemination of a river channel-bed monitor...... 3 3. Graph showing cross sections from historic flood measurements made at the downstream face of structure L-344 crossing the Chariton River near Prairie Hill, Missouri...... 5 4. Photgraphs showing installation of a river channel-bed monitor on structure L-344 over the Chariton River near Prairie Hill, Missouri...... 6 5. Graph showing cross sections from historic flood measurements made at the downstream face of structure L-534 crossing the Chariton River at Novinger, Missouri...... 8 6. Photgraphs showing installation of river channel-bed monitors on structure L-534 over the Chariton River at Novinger, Missouri...... 9 7. Predicted contraction and pier scour depths based on the 1993 flood for piers 1 through 14 and river channel-bed monitor design at pier 12 at structures A-1850 and A-4936 over the Mississippi River at Mehlville...... 10 8. Photgraphs showing installation of river channel-bed monitors on structures A-1850 and A-4936 over the Mississippi River at Mehlville, Missouri...... 12 9–10. Graphs showing— 9. River channel-bed elevation at the downstream side of the upstream column of pier 4 and river stage from August 21, 2007, through August 21, 2009, for the Chariton River near Prairie Hill, Missouri (structure L-344)...... 14 10. River channel-bed elevation at the downstream side of the upstream and downstream columns of pier 7 and river stage from May 22, 2008, through August 22, 2009, for the Chariton River at Novinger, Missouri (structure L-534).....19 iv

11–13. Graphs showing— 11. River channel-bed elevation at the downstream nose of pier 12 and river stage from October 24, 2008, through August 24, 2009, for the Mississippi River near Mehlville, Missouri (structures A-1850 and A-4936)...... 22 12. River channel-bed elevation at the upstream nose of pier 12 and river stage during the period of October 24, 2008, through December 31, 2008, for the Mississippi River near Mehlville, Missouri (structures A-1850 and A-4936)...... 24 13. Bathymetric surveys conducted October 2, 2008, May 13, 2009, and July 8, 2009, using multibeam sonar at the Mississippi River near Mehlville, Missouri (structures A-1850 and A-4936)...... 25

Table

1. Depth soundings near locations of river channel-bed monitors on the downstream side of the indicated column of bridges on the Chariton River in Missouri...... 13

Conversion Factors

Inch/Pound to SI Multiply By To obtain Length inch (in.) 2.54 centimeter (cm) inch (in.) 25.4 millimeter (mm) foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometer (km) Flow rate foot per second (ft/s) 0.3048 meter per second (m/s) cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s) hertz (Hz) 0.001 kilohertz (kHz)

Left and right pertain to an observer facing downstream. Vertical coordinate information is referenced and noted as either “National Geodetic Vertical Datum of 1929” (NGVD 29) or the “North American Vertical Datum of 1988” (NAVD 88). Elevation, as used in this report, refers to the distance above the vertical datum. Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

By Paul H. Rydlund, Jr.

Abstract Introduction

Scour and depositional responses to hydrologic events Channel-bed dynamics of scour and deposition are have been important to the scientific community studying natural phenomena in alluvial systems in which bed and bank sediment transport as well as potential effects on bridges materials erode and re-deposit through the action of moving and other hydraulic structures within riverine systems. water. For a given hydrographic event, bed scouring is typi- A river channel-bed monitor composed of a single-beam cally observed on the rising limb of the hydrograph. At some transducer was installed on a bridge crossing the Chariton point beyond the peak of the hydrograph, deposition begins River near Prairie Hill, Missouri (structure L-344) as a to occur on the receding limb. The addition of a hydraulic pilot study to evaluate channel-bed change in response to structure, such as a bridge, exacerbates scouring conditions the hydrologic condition disseminated from an existing due to a change in flow area and velocity. To better understand streamgage. Initial results at this location led to additional the effects of scour around bridges, classifications such as installations in cooperation with the Missouri Depart- local and contraction scour (Richardson and Davis, 2001) need ment of Transportation at an upstream Chariton River to be defined. The primary classification of scour associated streamgage location at Novinger, Missouri (structure with piers or pile bents is defined as local scour, which is the L-534) and a Mississippi River streamgage location near result of increased velocities caused by flow impinging on an Mehlville, Missouri (structures A-1850 and A-4936). In impediment. Contraction scour, which is a result of a reduction addition to stage, channel-bed elevation was collected at in flow area from a bridge, may also exist at piers or pile bents all locations every 15 minutes and transmitted hourly to as an additive effect to produce total scour. a U.S. Geological Survey database. Bed elevation data Prior assessment methods conducted by the U.S. Geo- for the Chariton River location at Novinger and the Mis- logical Survey (USGS) in cooperation with the Missouri sissippi River location near Mehlville were provided to Department of Transportation (MoDOT) have been used to the World Wide Web for real-time monitoring. Channel- estimate overall scour depths in the state of Missouri since bed data from the three locations indicated responses to 1991 (Huizinga and Rydlund, 2004). Assessments by the hydrologic events depicted in the stage record; however, USGS were conducted in three approaches: potential-scour notable bedforms apparent during inter-event flows also assessment (Level 1), rapid estimation assessment (Level 1+), may have affected the relation of scour and deposition and a detailed hydraulic assessment (Level 2). Level 2 assess- to known hydrologic events. Throughout data collection ments were used to compute contraction, local, and abutment periods, Chariton River locations near Prairie Hill and scour depths and ultimately were used to determine which Novinger reflected bed changes as much as 13 feet and 5 bridges were scour critical and would require further moni- feet. Nearly all of the bed changes correlated well with the toring or application of scour countermeasures (Richardson hydrographic record at these locations. The location at the and Davis, 2001; Huizinga and Rydlund, 2004). As a result Mississippi River near Mehlville indicated a much more of these assessments conducted to determine “scour-critical” stable channel bed throughout the data collection period. bridges, resource managers associated with the maintenance of Despite missing data resulting from damage to one of the state-owned bridges have had a need to monitor channel-bed river channel-bed monitors from ice accumulation at the scour in the vicinity of pier and pile bents as well as abutments upstream nose of the bridge pier early in the record, the at existing and newly constructed bridges. record from the downstream river channel-bed monitor River channel-bed monitoring historically has been demonstrated a good correlation (regardless of a 7 percent conducted during pre- and post-flood conditions requiring the high bias) between bedform movement and the presence of deployment of personnel to known scour-critical bridges. The bedforms surrounding the bridge as indicated by coinci- limitation of personnel, resources, and time, make effective dent bathymetric surveys using multibeam sonar. channel-bed monitoring before, during, and after substantial 2 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 flood events difficult. Technological advances in sonar, location on the Mississippi River (fig. 1) between August 20, coupled with the use of data collection platforms (hereinafter 2007, and August 24, 2009. referred to as DCP’s), satellite telemetry and dissemination The integration of an RCBM with a DCP used to record through the World Wide Web (hereinafter referred to as the and transmit river stage at streamgages has allowed the moni- Web), allow channel-bed monitoring in a real-time manner. toring of bed dynamics as a function of river stage (fig. 2). High-frequency single-beam transducers, the primary compo- On an hourly basis, the DCP transmits stage sensor and bed nents of river channel-bed monitors (hereinafter referred to as monitoring inputs collected every 15 minutes through a series RCBM’s), provide good channel bottom definition and depth of satellites to a USGS office where the data are automatically range and have been used extensively in marine environments uploaded into the USGS National Water Information System as a reliable means of navigation. Well-protected RCBM’s, (NWIS) database (http://waterdata.usgs.gov/nwis). Data are installed and operated by the USGS in cooperation with updated to the Web from NWIS, resulting in a total time from MoDOT, have provided monitoring at critical locations near field transmission to Web in approximately 7 to 8 minutes bridge piers for two locations on the Chariton River and one (U.S. Geological Survey, 2009, fig. 2).

95° 93° 91°

06904500 - Chariton River at Novinger

40° Chariton River Chariton 06905500 - Chariton River near Prairie Hill

Missouri River

07010200 - Mississippi River at Mehlville Mississippi River

38°

36°

Base from U.S. Geological Survey digital data, 1992, 1:24,000 0 40 80 120 160 MILES Universal Transverse Mercator projection Zone 15 0 60 120 180 240 KILOMETERS

EXPLANATION

06904050 Streamgage with river channel-bed monitor and station number Southern extent of glaciation (Missouri Division of Geology and Land Survey, 1979) Study area rivers

Figure 1. Location of river channel-bed monitors in Missouri. Introduction 3 Encapsulating material Sound absorbing material Piezoceramic element Acoustic window Housing CABLE Local Readout Ground Station (LRGS) Shielded cable National Water Information System (NWIS) Downstream bridge face Bed monitor cable conduit Command and data acquisition Streamgage housing stage sensor, data collection platform, data string conversion device, and wiring power supply Flow Stage sensor conduit Water stage Water Downstream bridge face Internal configuration, installation, and data dissemination of a river channel-bed monitor.

Bed monitor cable conduit To stage sensor To Figure 2. 4 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

Purpose and Scope River Channel-Bed Monitor Installation The purpose of this report is to document RCBM instal- and Data Collection lations and real-time acquisition of data during 2007–09 accessed from an internal Web link at two locations on the Site selections for RCBM installations were based on Chariton River and one location on the Mississippi River. This known occurrences of substantial scour and deposition and report provides a method of evaluating channel-bed elevation locations identified as potentially scour critical from Huizinga change throughout a hydrograph at discrete locations under- and Rydlund (2004) in cooperation with MoDOT. Glacial till neath bridges. The installation of RCBM’s, integrated with covers the majority of the landscape surrounding the Chariton existing 15-minute recording DCP’s and hourly telemetry, and Mississippi River Basins within Missouri (Raisz, 1957; provide a means by which to investigate the relation between fig. 1) and is composed of a mixture of clay, sand, and gravel. scour and deposition of the channel bed hydrographically in Eroded glacial till sediments of sand and silt dominate channel comparison with river stage. Documentation of the scour and beds within the Chariton and Mississippi River Basins, which deposition relation illustrates overall channel-bed stability, the have a short-duration scour and deposition process as velocity, presence of bedforms, and an indication of bed equilibrium at bed shear stress, and sedimentation occur during rising and the Chariton and Mississippi River locations. receding river stages (Leopold and others, 1964). For effective monitoring of the river channel bed, instal- lations were site-specific. The RCBM’s used in this data Description of River Channel-Bed Monitors collection effort could not receive a message sending protocol known as a “ping” less than 1.5 feet without a resonating The RCBM’s used in this application are composed of effect of the sonar, which produced a false, secondary depth a single-beam transducer commonly used in the light- and echo that would offset the actual depth of the channel bed. As leisure-marine markets. The transducer utilizes Smart TM a result, the installation of the RCBM had to occur in a pool sensor technology composed of active electronics within the with sufficient depth to provide the necessary 1.5 feet of clear- transducer body allowing functionality of both the transducer ance below the RCBM. In addition to depth concerns, protec- element and signal processor. The structure of the transducer is tion from debris was needed to avoid an intermittent loss of a piezoceramic element partially surrounded by sound-absorb- data or damage to the RCBM. Installations at the Chariton ing material such as cork or foam that aids in dampening River sites and one installation at the Mississippi River site unwanted vibrations. The piezoceramic element and sound- occurred on the downstream side of columns or piers that absorbing material are contained within encapsulating material existed within a sufficient pool to ensure protection and con- composed of urethane and sealant that fills the housing. The tinual monitoring. housing is a sturdy composition of stainless steel that protects the brittle ceramic element within (Airmar Technology Cor- Chariton River near Prairie Hill (Structure L-344) poration, 2006; fig. 2). A shielded cable enclosing conductors of electrical current is permanently attached to the transducer. A USGS streamgage located on structure L-344 over the RCBM’s installed at the Chariton and Mississippi River loca- Chariton River near Prairie Hill (06905500) has been in opera- tions are optimized to transmit at a frequency of 235 kilohertz tion since September 1953. Historic flood discharge measure- with a narrow beam angle of 7 degrees through a urethane ments made with a current meter suspended above a sounding acoustic window (Airmar Technology Corporation, 2006). weight were used to obtain depth measurements at approxi- To ensure data communication, a conversion device was mately 20 to 30 locations across the channel during each used to convert the depth value, expressed as the National discharge measurement at the downstream face of structure Marine Electronics Association (NMEA 0183) data string, L-344 (fig. 3). Historic high-flow measurements have indi- from the RCBM’s to the Serial Data Interface at 1200 Baud cated the frequent accumulation of a sizeable debris raft on the (SDI-12) required by the DCP. The DCP sends an address center pier, which effectively increases pier width, decreases query at programmed intervals of 15 minutes to the conver- the bridge-opening area, and ultimately contributes to scour sion device. Once submitted, the conversion device “wakes and potential long-term degradation (Becker, 1994). Cross up” from a lower-power “sleep” mode to collect NEMA 0183 sections depicted in figure 3 illustrate substantial channel-bed depth value data from the RCBM. The data are then stored in change, indicating frequent scour and deposition, making this a temporary buffer, converted to SDI-12, then sent to the DCP. a good pilot study location for an RCBM. The conversion device allows the user to enter an offset value The existing streamgage utilizes a pressure sensor that when installing the RCBM and evaluating the current water is used to collect water stage measurements. The data from depth. The DCP receives the depth value data string as SDI-12 an RCBM installed on the downstream side of the upstream from the conversion device and transmits it along with other conical column of pier bent 4 (fig. 4) was integrated with real- resident streamgage parameters every hour by satellite telem- time disseminated parameters of the existing streamgage. A etry to the USGS NWIS database. 3-inch section of schedule 40 galvanized steel pipe was used River Channel-Bed Monitor Installation and Data Collection 5 WEST Pier 5

abutment

Pier 4 Pier Pier 3 Pier

DISTANCE FROM LEFT END OF END OF FROM LEFT IN FEET BRIDGE, DISTANCE Pier 2 Pier Description As-built, June 23, 1949 September 24, 1959 March 29, 1960 July 10, 1969 April 22, 1973 May 8, 1978 June 9, 1993 July 8, 1993 July 23, 1993 August 19, 1993 May 24, 1995 November 23, 1999 Pier 1 abutment bed Channel EAST Cross sections from historic flood measurements made at the downstream face of structure L-344 crossing Chariton River near Prairie Hill,

20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 -

670 660 650 640 630 620 610 600 590 580 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 3. Missouri. 6 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

Installation of 3-inch galvanized steel pipe encasing the transducer Installation of 1-inch to 3-inch galvanized steel pipe encasing the head and shielded cable on the downstream side of the upstream transducer head and shielded cable on the downstream side of the conical column of pier 4. upstream conical column of pier 4 and between girders.

Three-inch galvanized steel pipe with offset encasing the transducer head, which is flush with pipe. Offset designed to prevent acoustic signal interference from pier and footing.

Figure 4. Installation of a river channel-bed monitor on structure L-344 over the Chariton River near Prairie Hill, Missouri. River Channel-Bed Monitor Installation and Data Collection 7 as conduit to protect the transducer head and shielded cable at Mississippi River at Mehlville (Structures the lower portion of the pier (fig. 4). A-1850 and A-4936) Schedule 40 steel pipe was used to protect the transducer head and cable from debris, in addition to providing stability The Mississippi River crossing near the town of and rigidity in the overall installation. Once the installation Mehlville, Missouri, is better known as the Jefferson Barracks was complete, the power, data, and ground wires were con- Bridge (hereinafter referred to as the JBB), which is composed nected to the NEMA 0183 to SDI-12 conversion device, which of east- and west-bound structures on I-255 that span the Mis- was subsequently wired to the DCP and programmed as an sissippi River south of St. Louis. The JBB was a location used additional SDI-12 parameter to be received and transmitted. for monitoring channel-bed changes resulting from the 1993 The initial depth measurement acquired by the data collector flood. Scour measurements made during the 1993 flood indi- was checked in the field for accuracy. At this location, there cated dunes as high as 6 to 8 feet located upstream from piers was no offset that was needed. The initial and three subsequent 8 and 9 (Mueller and others, 1995), and a scour assessment depth measurements were verified using a measuring rod dur- conducted by the USGS in 2003 (Huizinga and Rydlund, 2004) ing the next hour (four 15-minute readings). for the 1993 flood indicated potential local pier scour at piers 7 In addition to existing streamgage parameters received through 12 (fig. 7). Installations of RCBM’s at overbank piers through a Local Readout Ground Station (LRGS), decoded 7 through 11 were not feasible because the pier columns are 15-minute data from the RCBM were populated into a newly substantially recessed underneath the bridge deck and a large established data descriptor, then converted to the current oblique angle is required for the transducer head to be unob- streamgage datum within the USGS Automated Data Process- structed by the footer and seal course. The scour assessment ing System (ADAPS) (Bartholoma and others, 2003). These conducted in 2003, based on the 1993 flood, predicted a larger data were not disseminated by the Web, but resided internally amount of scour at overbank piers 7 through 11 (as a result of within the USGS to be monitored as a pilot study. partially exposed foundations) than at navigation channel piers 12 and 13 (fig. 7). However, preliminary soundings at pier 12 identified a partially exposed foundation in 2008, which, Chariton River at Novinger (Structure L-534) when coupled with the feasibility of RCBM installations at the upstream and downstream nose of the pier, made this pier an Structure L-534 crossing the Chariton River at Novinger acceptable location to monitor channel-bed change. was considered to be a good location for monitoring because Substructure details from MoDOT bridge plans (Mis- of a partially exposed foundation at pier 7 detected in a 1995 souri Department of Transportation, 1977) provided the basis channel-bed survey, a non-cohesive sand channel bed, and for an RCBM design at pier 12 (fig. 7). The complication in an indication of potential pier and contraction scour during a this design was ensuring that the acoustic signal had adequate 1995 scour assessment conducted by the USGS (Huizinga and clearance from the footer and seal course, yet minimizing the Rydlund, 2004). A USGS streamgage (06904500) has been in angle of the RCBM so that the signal would be returned and operation at this location since October 1956. Historic flood not reflected off the channel bottom in a direction away from discharge measurements (fig. 5) indicate a dynamic sand chan- the RCBM. Another concern was ensuring adequate protection nel bed that has scour and deposition, and has migrated later- to the RCBM (particularly at the upstream nose) on a large ally as a result of a riprap blanket constructed underneath the river (approximately 2,000 feet wide; Huizinga and Rydlund, left approach span between 1993 and 1995 based on MoDOT 2004) with substantial hydrodynamic force and potential float- records (Ken Foster, Federal Highway Administration, oral ing debris. commun., 2009). Based on the upstream and downstream protruding Infrastructure associated with the USGS streamgage length of the footer and seal course from pier 12, an angle shelter was mounted on the cap at the downstream side of pier of 22 degrees was determined to provide adequate clearance 7, which provided accessibility for the installation of the steel to the channel bottom (fig. 7). Independent tests were con- pipe that houses the RCBM at the upstream and downstream ducted in the field with an RCBM positioned at a variety of side of pier 7. A section of 1-inch pipe was installed on the vertical departures. The results of these tests showed that this downstream side of the downstream conical column parallel- angle (22 degrees) was sufficient to ensure signal return from ing the existing pressure sensor conduit (fig. 6) and another the channel bottom without reflection from the transducer section of 1-inch pipe was installed on top of the cap and on head. Proper protection of the RCBM and shielded cable was the downstream side of the upstream conical column (fig. 6). afforded by a 3-inch pipe used to encase the RCBM. The Similar to the installation on structure L-344 near Prairie 3-inch pipe transitioned to a 1-inch pipe protected by 3- by Hill, a reducer allowed the transition from the 1-inch pipe 3-inch steel angle. The 3- by 3-inch angle provided protec- to the 3-inch pipe, which ultimately housed the transducer tion to the location of a beveled edge (fig. 7), identified as a heads below the water surface at the downstream side of the location of observed high water of record in MoDOT bridge upstream and downstream columns (fig. 6). Transmitted data plans (Missouri Department of Transportation, 1977). Above from this location were processed in ADAPS and disseminated the beveled edge on the upstream and downstream nose of pier through the Web. 12, polyvinylchloride (PVC) conduit was used to house the 8 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 ,

WEST

Pier 1 Pier Pier 2 Pier

Description Pier 3 Pier 1953As-built, January 21, March 14, 1961 April 21, 1973 October 2, 1986 June 14, 1990 May 12, 2002 March 18, 1998 July 17, 1995 bed

Channel Pier 4 Pier

Pier 5 Pier

Pier 6 Pier Pier 7 Pier

DISTANCE FROM LEFT END OF END OF FROM LEFT IN FEET BRIDGE, DISTANCE

Pier 8 Pier

Pier 9 Pier Pier 10 Pier

50 100 150 200 250 300 350 400 450 500

Pier 11 Pier Pier 12 Pier 0 EAST Cross sections from historic flood measurements made at the downstream face of structure L-534 crossing Chariton River Novinger

50

780 770 760 750 740 730 720 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 5. Missouri. River Channel-Bed Monitor Installation and Data Collection 9

Existing pressure sensor conduit

Galvanized steel pipe

Existing streamgage shelter on the downstream side of pier 7. Note the galvanized steel pipe fastened on the conical column encasing the river channel-bed monitor shielded cable. Installation of pipe junction to accommodate the downstream and the upstream river channel-bed monitor cables. Note the galvanized steel pipe that is parallel to the existing conduit for the pressure transducer on the downstream column.

1-inch to 3-inch pipe Wiring of NEMA 0183 to SDI-12 conversion devices necessary to ensure transition recording and transmission of river channel-bed monitor depth soundings.

Installation of galvanized steel pipe along the top of the cap and continuing along the downstream side of the upstream conical column. Note the 1-inch to 3-inch pipe transition to accommodate the transducer head below the water surface.

Figure 6. Installation of river channel-bed monitors on structure L-534 over the Chariton River at Novinger, Missouri. 10 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

700

650

600

550

500 Pier 13 Pier 12 West abutment West Pier 14 Pier 11 Pier 10 Pier 9 Pier 8 Pier 7 Pier 6 Pier 5 Pier 4 Pier 3

450 Pier 2 Pier 1 East abutment

Ground 400 surface Ground surface 1977 11/19/2002 350

Approximate rock line 300 (from MoDOT core logs)

250 Water surface elevation at upstream bridge face = 422.8 feet Contraction scour 200 NOTE: Pier numbers correspond to Missouri Department of Transportation (MoDOT) plans.

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM ELEVATION, NOTE: Abutment scour is not shown. Pier scour 150 -250 0 250 500 750 1,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750 3,000 3,250 3,500 3,750 4,000 4,250 DISTANCE FROM LEFT END OF BRIDGE, IN FEET

Top view of front of lower section of pier 12

Pier caps 180 feet from upstream to downstream end

90˚ bend 1-inch steel pipe inside 3-inch by 3-inch steel angle Pier cap 2-foot 3-inch 12 feet radius 90˚ bend in 1-inch steel pipe Construction joint 4 - 10-foot sections and Column 1 - 5 foot section of 16 feet 8 inches 1-inch PVC pipe 45 feet (minimum of two 6.5 feet to beveled edge of pier sections of steel Construction on bottom) joint

Column 2 - 90˚ bends 16 feet 8 inches in steel pipe Additional sections 10 feet long: Construction joint 1-inch steel pipe behind 3-inch by 3-inch steel angle with 4 - 10-foot sections and 2-inch by 2-inch tabs for mounting Pointed-nose 2 - 6 foot sections of 3-inch by 3-inch steel Offset conduit based column on lowest section (with 26 feet angle and 1-inch steel pipe (depending on transducer mount) length of lowest section) For top section, cut 52 feet Construction conduit flush with joint top of angle (thread for 90˚ bend)

Pointed-nose Transducer head mounted 1-inch steel pipe behind column 6 feet above lower 3-inch by 3-inch steel 26 feet construction joint angle welded to top of transducer mount with 2-inch by 2-inch tabs 6 feet Construction for mounting joint Transducer mount Allow 1 foot of steel pipe Pedestal to extend beyond top 10 feet of steel angle Footer 8 feet Acoustic footprint Figure 7. Predicted contraction and 36 feet 11˚ on each side pier scour depths based on the 1993

Seal course flood for piers 1 through 14 and river 18 feet 3-inch steel pipe with channel-bed monitor design at pier 12 wedge cut out to make 22˚ angle at structures A-1850 and A-4936 over the Mississippi River at Mehlville. Side view of front of pier 12 River Channel-Bed Monitor Results 11 shielded cable along the remainder of the pier nose, along the of bed material is done in such a way that new resistance is pier cap, and into the shelter. created, ultimately returning a steady state to the channel. Installation of RCBM’s at the JBB required a crane and These dynamics describe the foundation for development and suspended basket in which to work from the water surface up migration of bedforms (Leopold and others, 1964). to the cap along the upstream and downstream nose of pier 12 Movement in the channel-bed record during inter-event (fig. 8). Expandable anchor bolts were used to mount the steel flows indicated the existence of these bedforms. Other anoma- pipe and angle along the pier nose through pre-drilled holes in lies observed in the channel-bed record may indicate debris the 2- by 2-inch tabs located at increments along the 10-foot accumulation. Although the timing for scouring and deposition sections (figs. 7 and 8). In contrast to the Chariton River sites, was not always expected based on the shape of the hydro- this location did not have a pre-existing continuous stage graph, overall results for most monitoring locations indicated recording device. This required the installation of a water direct responses to hydrologic events. stage sensor and DCP to provide corresponding hydrographic RCBM’s identified some noise and backscatter, primarily record. A non-contact water surface sensor was clamped to the as a result of sediment transport and periodic events of sub- substructure girders of the bridge and the attached shielded merged debris movement. In addition, substantial noise was cable consisting of power, data, and ground wires was run to evident during periods where sounding depths were approxi- the shelter housing the DCP (fig. 8). mately 1.5 feet or less. At shallow depths, the 235 kilohertz frequency transmitting from the RCBM caused “vibration” or “ringing” as the transducer head “pinged” the channel bottom at close distances. During these periods (specifically for struc- River Channel-Bed Monitor Results ture L-344), a false second return, or echo, which was offset in the channel bottom record, was evident with accompany- All monitoring locations were established to provide ing noise. Depth soundings that occurred every 15 minutes channel-bed data near bridge piers. General channel-bed resulted in a large data set. The amount of data allowed the behavior, such as scour and deposition, are somewhat altered observation of well-defined trends through periodic noise and because of the effect of a bridge pier as a flow impediment. ultimately justified a smoothing of the record without compro- Typically, the scouring condition of the channel bed is exacer- mising the true representation of the channel bed. To further bated from a horseshoe vortex caused by increased velocities ensure accurate channel-bed record during excessive noise or near the base of the pier at the upstream nose that contributes offset channel-bed signatures resulting from shallow depths, to the removal of bed material (Richardson and Davis, 2001). physical depth measurements periodically were made to the Data received from RCBM’s outside the vicinity of impedi- channel bed and translated to datum. RCBM data were always ments likely would illustrate a better correlation of scour and within 0.4 foot of the physical measurement (table 1). deposition to the rising and falling limb of a hydrograph rather than monitoring channel-bed change downstream or upstream from a pier during a hydrologic event. Chariton River near Prairie Hill (Structure L-344) In addition to the effects of an impediment, channel- bed changes inconsistent with theoretical expectations of On August 20, 2007, an RCBM was installed behind the scouring and deposition based on the hydrographic record upstream conical column of pier 4 as a pilot study. Within a might indicate the presence of bedforms, which are structures few days, a 12-foot rise in stage triggered approximately 3 to 4 resulting from the movement of bed material due to flow. In feet of scour (fig. 9). The scoured bed condition was sustained sand channel beds, the sequence of bedform development can for nearly 17 days (fig. 9) until the presence of a bedform be correlated to an increase in velocity (Leopold and others, began to fill the hole during the middle of September 2007. 1964). In most sand-bed channels, ripples or dunes exist as Although the majority of the channel-bed record reflected a result of velocities present during median or base flows; some sort of direct hydrologic response at this location, the however, as velocities begin to increase, dunes tend to dis- presence of bedforms as well as the flow impediment on which sipate to a point where flow begins to approach a state where the RCBM was installed (pier 4) had contradictory or additive forces, including gravity and viscosity, are overcome by the effects on expected scour and depositional behavior. A poten- increasing movement of water. At this point (known as critical tial migrating bedform appeared before substantial scouring flow), antidunes begin to form in relation to surface waves that occurred July 24, 2008, as a result of increasing velocities and these antidunes progressively move upstream, continu- associated with the rising limb of the peak. The presence of ally forming, dissipating, and reforming (Leopold and others, this bedform may have produced an additive effect whereby 1964). In general, erosion of ripples and dunes occurs as a scour was increased at the peak as the dune trough crossed the result of a lack of resistance of bed material with increasing scour hole. Conversely, a filling effect can arise from cases fluid stress. However, the amount eroded cannot be conveyed where the crest of the bedform is passing through the scour as bed load without an increase in applied stress; therefore, hole (Pittaluga and others, 2004). For example, the rising limb bed material is re-deposited, initially representing an unstable of a prior peak on June 24, 2008, possessed nearly the same channel condition (Leopold and others, 1964). A re-deposition magnitude and duration as compared to the July 24, 2008, 12 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 Suspended personnel basket Suspended personnel basket Safety boat used during installation of river channel-bed monitors. Note basket used to install pipe along the upstream and downstream pier nose. Installation of shielded cable in 1-inch steel pipe under 3-inch steel angle along the upstream nose of pier bent 12 using a suspended basket. Installation of shielded cable in 1-inch steel pipe under 3-inch steel angle with expandable anchor bolts. Installation of non-contact water surface sensor clamped to girders underneath bridge. Installation of river channel-bed monitors on structures A-1850 and A-4936 over the

Three-inch galvanized steel pipe angled to clear footer and seal course, with enclosed transducer head flush pipe. Note 3-inch angle welded to casing. Wiring of river channel-bed monitors and non-contact water surface sensor to a shelter housing the NEMA 0183 SDI-12 data conversion devices and data collection platform. Figure 8. Mississippi River at Mehlville, Missouri. River Channel-Bed Monitor Results 13

Table 1. Depth soundings near locations of river channel-bed monitors on the downstream side of the indicated column of bridges on the Chariton River in Missouri

[ft, feet; RCBM, river channel-bed monitor; NGVD 29, National Geodetic Vertical Datum of 1929; --, no measurement]

Upstream column of pier 4 Upstream column of pier 7 Downstream column of pier 7 of structure L-344 of structure L-534 of structure L-534

Date Measured RCBM bed Date Measured RCBM bed Measured RCBM bed bed elevation elevation bed elevation elevation bed elevation elevation (NGVD 29) (NGVD 29) (NGVD 29) (NGVD 29) (NGVD 29) (NGVD 29) (ft) (ft) (ft) (ft) (ft) (ft) 21-Aug-07 631.2 631.1 22-May-08 733.3 733.1 731.8 731.6 18-Sep-07 631.7 631.8 2-Jul-08 -- -- 728.8 728.6 6-Mar-08 627.7 627.4 7-Jan-09 -- -- 729 729.3 28-Sep-08 632.6 632.5 8-Jul-09 730.3 729.9 730.6 730.9 21-Jul-09 630.8 630.5 peak event, yet showed a minimal scouring response possibly Chariton River at Novinger (Structure L-534) as a result of the presence of bedforms. From August 21, 2007, through February 21, 2008, On May 22, 2008, RCBMs were installed on the down- channel-bed records depict channel-bed elevation changes as stream side of the upstream and downstream columns of large as 4 feet and the presence of bedforms evident during pier 7. After the installation, the channel-bed record appeared inter-event flows in September, November, and the begin- to be depicting bed changes for the upstream column (fig. 10), ning of December (fig. 9). From February 21 through August but progressively became steady and flat, indicating exposure 21, 2008, channel-bed changes were as large as 13 feet, of the footer behind the upstream column. After the installa- and indications of substantial bedforms occurred during the tion of the RCBM at the downstream column, the RCBM was middle of May and toward the end of July during inter-event sounding the footing. The transducer head was moved beyond flows (fig. 9). The maximum channel-bed change of 13 feet the footer an additional foot (extended from 2 to 3 feet) at both was attributable to a record peak flood event at this location upstream and downstream columns to ensure adequate sound- of 38,400 cubic feet per second that occurred on July 27, ing of the channel bed (fig. 10). 2008. This was the largest recorded peak flood in 78 years of The downstream channel-bed record depicted an eleva- record and was statistically defined within a 0.2 to 1 percent tion of 731.5 feet, which was within 0.2 foot from the elevation annual exceedence probability or between a 500- and 100-year of the top of the footer of 731.7 feet, as indicated from MoDOT recurrence (Robert Holmes, U.S. Geological Survey, written bridge plans. As bed monitoring continued at the downstream commun., 2009). From August 21, 2008, through February column from May 22 through November 22, 2008, depositional 21, 2009, bed changes as large as 10 feet and the presence of responses to hydrologic events occurred near the end of June, end bedforms during inter-event flows in November were noted of July, and middle of September. A period of record peak flood (fig. 9). Finally, from February 21 through August 21, 2009, event of 30,200 cubic feet per second occurred July 25, 2008, channel-bed changes were as large as 5 feet, but bedforms and was the largest recorded flood in 83 years of record, with a could not be distinguished during this period (fig. 9). As previ- statistically defined annual exceedence probability between 2 to ously stated, the channel bed responded to hydrologic events, 4 percent, or in the range of a 50- to 25-year recurrence (Robert including an event beginning August 17, 2009, that depicted Holmes, U.S. Geological Survey, written commun., 2009). The scouring on the rising limb, which continued through the end RCBM at the upstream column revealed an exposed footing, but of the data collection period on August 21, 2009. the channel-bed record at the downstream column did not indicate Channel-bed data collection at this location was com- any substantial response to the magnitude of this peak (fig. 10). promised from August 15 to September 12, 2008, as a result Channel-bed monitoring at the downstream column indicated of deposition of sediments close to the transducer head of the channel-bed changes as large as 3 feet and difficulty in ascertain- RCBM (fig. 9). The occurrence of this deposition produced ing the presence of bedforms from May 22 through November an indistinguishable channel-bed signature as a result of noise 22, 2008. For the same period of time, the footer at the upstream and secondary echoes. In addition, no valid data were col- column was progressively more exposed, which was made appar- lected during middle and late January 2009 because of ice ent by a steady and flat channel-bed signature during July through accumulation (fig. 9). Another period of missing channel-bed October. Channel-bed fluctuations at the upstream column were and stage record occurred March 14 through March 16, 2009, as much as 1.5 feet before the footer was exposed and after the as a result of equipment power failure. transducer was moved during this period. 14 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 FEBRUARY 4 8 12 16 20 2008 River stage Channel bed Channel-bed verification ough August 21, 2009, for the JANUARY 4 8 12 16 20 24 28 Elevation of transducer head = 632.9 feet DECEMBER 4 8 12 16 20 24 28 NOVEMBER 4 8 12 16 20 24 28 2007 OCTOBER 4 8 12 16 20 24 28 SEPTEMBER 4 8 12 16 20 24 28 August 21, 2007–February 2008 24 28 River channel-bed elevation at the downstream side of upstream column pier 4 and river stage from August 21, 2007, thr AUGUST

647.5 645.0 642.5 640.0 637.5 635.0 632.5 630.0 627.5 625.0 622.5 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 9. Chariton River near Prairie Hill, Missouri (structure L-344). River Channel-Bed Monitor Results 15 AUGUST 4 8 12 16 20 Missing data resulting from shallow depth noise Period of record (78 years) peak JULY ough August 21, 2009, for the 4 8 12 16 20 24 28 JUNE 4 8 12 16 20 24 28 2008 MAY 4 8 12 16 20 24 28 February 21–August 21, 2008 APRIL 4 8 12 16 20 24 28 Elevation of transducer head = 632.9 feet MARCH River stage Channel bed Channel-bed verification 4 8 12 16 20 24 28 24 28 River channel-bed elevation at the downstream side of upstream column pier 4 and river stage from August 21, 2007, thr

FEBRUARY

657.5 655.0 652.5 650.0 647.5 645.0 642.5 640.0 637.5 635.0 632.5 630.0 627.5 625.0 622.5 620.0 617.5 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 9. Chariton River near Prairie Hill, Missouri (structure L-344).—Continued 16 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 FEBRUARY 4 8 12 16 20 River stage Channel bed Channel-bed verification Missing data resulting from ice accumulation 2009 ough August 21, 2009, for the JANUARY 4 8 12 16 20 24 28 DECEMBER 4 8 12 16 20 24 28 Elevation of transducer head = 632.9 feet NOVEMBER 4 8 12 16 20 24 28 2008 OCTOBER 4 8 12 16 20 24 28 August 21, 2008–February 2009 SEPTEMBER 4 8 12 16 20 24 28 Missing data resulting from shallow depth noise (generated by deposition of sediments close to the transducer head) 24 28 River channel-bed elevation at the downstream side of upstream column pier 4 and river stage from August 21, 2007, thr AUGUST

657.5 655.0 652.5 650.0 647.5 645.0 642.5 640.0 637.5 635.0 632.5 630.0 627.5 625.0 622.5 620.0 617.5 615.0 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 9. Chariton River near Prairie Hill, Missouri (structure L-344).—Continued River Channel-Bed Monitor Results 17 AUGUST 4 8 12 16 20 River stage Channel bed Channel-bed verification JULY ough August 21, 2009, for the 4 8 12 16 20 24 28 JUNE 4 8 12 16 20 24 28 2009 MAY 4 8 12 16 20 24 28 Elevation of transducer head = 632.9 feet APRIL 4 8 12 16 20 24 28 MARCH 4 8 12 16 20 24 28 February 21–August 21, 2009 Missing data resulting from equipment power failure 24 28 River channel-bed elevation at the downstream side of upstream column pier 4 and river stage from August 21, 2007, thr

FEBRUARY

660.0 657.5 655.0 652.5 650.0 647.5 645.0 642.5 640.0 637.5 635.0 632.5 630.0 627.5 625.0 622.5 620.0 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 9. Chariton River near Prairie Hill, Missouri (structure L-344).—Continued 18 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

During November 22, 2008, through May 22, 2009 stage must be below 370 feet (NAVD 88), which was not (fig. 10), RCBM data at both upstream and downstream col- reached throughout the remainder of data collection. umns were examined for correlation with hydrologic events. The downstream monitoring location documented Channel-bed scouring at both upstream and downstream channel-bed changes as large as 5 feet over the 182-day period columns appeared to be a response to increasing velocities of data collection. Monitoring from April 24 through August associated with rising limbs of hydrologic events occurring 24, 2009, continued to reveal subtle changes in bed elevation December 22, 2008, March 8, March 24, April 27, and May at the downstream nose (fig. 11). Grounding issues with equip- 16, 2009 (fig. 10). A subtle time lag appears to be evident ment during electrical storms caused missing data for several between event-related scouring from the upstream to down- complete and partial days during this data-collection period. stream monitoring locations. Overall, channel-bed elevation Bathymetric surveys were conducted on October 2, changes were as much as 5 feet at the upstream column and May 13, and July 8, 2009, using a multibeam sonar unit that 3 feet at the downstream column. Although bedforms may provided high-resolution bathymetry depicting a detailed be “concealed” as they contribute to the scour and deposition three-dimensional representation of the Mississippi River processes observed, a distinguishable bedform is evident at channel bed around the JBB. The multibeam sonar unit uses the upstream column during inter-event flows in late January acoustic energy and records reflected echo from a series and through the month of February. During the latter part of of pulses that are distributed in a swath across the riverbed February to the beginning of March, the transition (occurring (National Oceanic and Atmospheric Administration, 2009). February 26) of a bedform, as depicted from the upstream Sound pulse generators and receivers used in this application monitoring location to the downstream monitoring location, created a swath that was 130 degrees wide perpendicular to, may be apparent (fig. 10). and 0.5 degrees wide parallel to, a survey line, and contained During May 22 through August 22, 2009, channel-bed 512 individual points representing depth across the swath changes as large as 6 feet occurred at the upstream column, (Richard Huizinga, U.S. Geological Survey, written com- and changes as large as 3 feet occurred at the downstream mun., 2009). A bathymetric survey conducted on October 2, column (fig. 10). An inter-event flow period occurred July 12 2008, did not indicate any change in channel-bed elevation or through August 12, 2009, for which there was no channel- presence of distinguishable bedforms; however, subsequent bed change or potential bedform movement. Hydrologic surveys conducted May 13 and July 8, 2009, revealed the events occurring earlier in this data collection period (May 22 presence of a bedform upstream from pier 12 (from the May through August 22, 2009) demonstrated channel-bed responses 13, 2009, survey) and the migration and presence of additional that were atypical compared to scour and depositional bedforms upstream and downstream from pier 12 (from the responses observed from November 22, 2008, through May July 8, 2009, survey) (fig. 13). The presence of bedforms from 22, 2009 (fig. 10). the bathymetric survey can be correlated to notable bedform movement (fig. 11) occurring June 7 through June 14, June 27 through June 30, and August 6 through August 23, 2009. Mississippi River at Mehlville (Structures A-1850 and A-4936)

Completion of the installation of RCBM’s at the upstream River Channel-Bed Monitor and downstream nose of pier 12 occurred on October 24, Uncertainty and Limitations 2008. Overall data collection at this location indicated mini- mal channel-bed elevation changes, without response to flow The Smart TM sensor transducer used in these applications events depicted in the hydrographic record. At the downstream has a depth range limitation from 0.5 meter to 100 meters nose, bed-elevation changes were less than 0.7 foot from Octo- (1.6 feet to 328.1 feet) and an accuracy of +/- 20 centimeters ber 24, 2008, through April 24, 2009 (fig. 11). Similar to the (7.9 inches) up to a depth of 5 meters (16.4 feet) and 3 per- downstream nose, the channel-bed elevation never changed cent of the depth from 5 meters to 100 meters (16.4 feet to more than 1.5 feet at the upstream nose of pier 12 during 68 328.1 feet) (Irene Robb, Airmar Technology Corporation, oral days of data collection from October 24 through December commun., 2009). The sensors assume a fixed speed of sound 31, 2008 (fig. 12). From December 22 through December 31, in water (1,500 meters per second; 4,921.3 feet per second); 2008, suspected ice accumulation began to interfere with the that in reality changes due to temperature and pressure (Irene RCBM, resulting in false channel-bed signatures and eventual Robb, Airmar Technology Corporation, oral commun., 2009; damage to the transducer head (fig. 12). Floating ice sheets John Bauchat, Airmar Technology Corporation, written com- were documented within the vicinity of the JBB during the mun., 2009). Physical measurements using a leveling rod at latter part of December 2008 throughout the middle of January both Chariton River locations never varied more than 0.4 foot 2009. A site visit was made February 6, 2009, to inspect the from the RCBM measurement (table 1). Readings from the RCBM above the water surface. Some damage had occurred rod were subtracted from the water surface elevation datum to the steel angle protecting the 1-inch pipe that housed the (NGVD 29) to obtain a channel-bed elevation that was com- shielded cable. To inspect and service the RCBM, the river pared to the current reading from the RCBM. The leveling River Channel-Bed Monitor Uncertainty and Limitations 19 NOVEMBER River channel- bed monitor extended beyond footer 4 8 12 16 20 , 2008, through August 22, Elevation of upstream transducer head = 737.1 feet River stage Channel bed at the upstream column Channel bed at the downstream column Channel-bed verification OCTOBER 4 8 12 16 20 24 28 SEPTEMBER 4 8 12 16 20 24 28 2008 AUGUST Exposed footer 4 8 12 16 20 24 28 JULY Period of record (83 years) peak 4 8 12 16 20 24 28 , Missouri (structure L-534).

JUNE 4 8 12 16 20 24 28 River channel- bed monitor extended beyond footer transducer head = 735.3 feet Elevation of downstream May 22–November 22, 2008 River channel-bed elevation at the downstream side of upstream and columns pier 7 river stage from May 22 MAY 24 28

770.0 767.5 765.0 762.5 760.0 757.5 755.0 752.5 750.0 747.5 745.0 742.5 740.0 737.5 735.0 732.5 730.0 727.5 725.0 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 10. 2009, for the Chariton River at Novinger 20 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 MAY 4 8 12 16 20 , 2008, through August 22, APRIL Elevation of downstream transducer head = 735.3 feet River stage Channel bed at the upstream column Channel bed at the downstream column Channel-bed verification 4 8 12 16 20 24 28 MARCH 2009 4 8 12 16 20 24 28 FEBRUARY 4 8 12 16 20 24 28 JANUARY 4 8 12 16 20 24 28 , Missouri (structure L-534).—Continued Elevation of upstream transducer head = 737.1 feet DECEMEBER 2008 4 8 12 16 20 24 28 River channel-bed elevation at the downstream side of upstream and columns pier 7 river stage from May 22 November 22, 2008–May 2009 24 28

NOVEMBER

765.0 762.5 760.0 757.5 755.0 752.5 750.0 747.5 745.0 742.5 740.0 737.5 735.0 732.5 730.0 727.5 725.0 722.5 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 10. 2009, for the Chariton River at Novinger River Channel-Bed Monitor Uncertainty and Limitations 21 AUGUST , 2008, through August 22, 2009, 3 6 9 12 15 18 21 River stage Channel bed at the upstream column Channel bed at the downstream column Channel-bed verification Elevation of downstream transducer head = 735.3 feet JULY 2009 3 6 9 12 15 18 21 24 27 30 JUNE , Missouri (structure L-534).—Continued 3 6 9 12 15 18 21 24 27 30 Elevation of upstream transducer head = 737.1 feet MAY 24 27 30 River channel-bed elevation at the downstream side of upstream and columns pier 7 river stage from May 22 May 22–August 22, 2009

750.0 747.5 745.0 742.5 740.0 737.5 735.0 732.5 730.0 727.5 725.0 722.5 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 10. for the Chariton River at Novinger 22 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 APRIL River stage Channel bed 4 8 12 16 20 24 MARCH 4 8 12 16 20 24 28 2009 FEBRUARY Elevation of transducer head = 369.3 feet 4 8 12 16 20 24 28 JANUARY 4 8 12 16 20 24 28 DECEMBER 4 8 12 16 20 24 28 2008 NOVEMBER 4 8 12 16 20 24 28 River channel-bed elevation at the downstream nose of pier 12 and river stage from October 24, 2008, through August 2009, f or Mississippi near October 24, 2008–April 2009

24 28 OCTOBER

405.0 402.5 400.0 397.5 395.0 392.5 390.0 387.5 385.0 382.5 380.0 377.5 375.0 372.5 370.0 367.5 365.0 362.5 360.0 357.5 355.0 352.5 350.0 ELEVATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1988 OF DATUM VERTICAL GEODETIC NATIONAL ABOVE FEET IN ELEVATION, Figure 11. Mehlville, Missouri (structures A-1850 and A-4936). River Channel-Bed Monitor Uncertainty and Limitations 23 River stage Channel bed AUGUST 4 8 12 16 20 24 369 368 364 365 367 366

nose of pier 12

DownstreamDOWNSTREAM NOSE OF PIER 12 357 356 355 358 July 8, 2009 359 360 361 362 363 353 354 354 JULY 356 4 8 12 16 20 24 28 Missing data resulting from equipment grounding issues 2009 (inset not to scale) Elevation of transducer head = 369.3 feet JUNE elevation contours in feet above NAVD 88 Sounding footprint location from bathymetric survey, 370 368 369 4 8 12 16 20 24 28 366 367 365 364

nose of 363 Downstream pier 12 362 361 360 359 358 357 May 13, 2009 356 355 356 354 MAY 4 8 12 16 20 24 28 April 24–August 24, 2009 River channel-bed elevation at the downstream nose of pier 12 and river stage from October 24, 2008, through August 2009, f or Mississippi near

APRIL 24 28

410.0 407.5 405.0 402.5 400.0 397.5 395.0 392.5 390.0 387.5 385.0 382.5 380.0 377.5 375.0 372.5 370.0 367.5 365.0 362.5 360.0 357.5 355.0 352.5 350.0 ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 OF DATUM VERTICAL AMERICAN NORTH ABOVE FEET IN ELEVATION, Figure 11. Mehlville, Missouri (structures A-1850 and A-4936).—Continued 24 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 River stage Channel bed End of transmission as a result of damage to transducer head ecember 31, 2008, for the Mississippi False channel bed signature as a result of suspected ice accumulation DECEMBER 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Elevation of transducer head = 369.3 feet 2008 356 355 NOVEMBER 354 353 352 353

of pier 12 October 2, 2008

Upstream nose 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Sounding footprint location from bathymetric survey, elevation contours in feet above NAVD 88 (inset not to scale) OCTOBER October 2,–December 31, 2008 River channel-bed elevation at the upstream nose of pier 12 and river stage during period October 24, 2008, through D

24 26 28 30

400.0 397.5 395.0 392.5 390.0 387.5 385.0 382.5 380.0 377.5 375.0 372.5 370.0 367.5 365.0 362.5 360.0 357.5 355.0 352.5 350.0 347.5 345.0 342.5 340.0 ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 OF DATUM VERTICAL AMERICAN NORTH ABOVE FEET IN ELEVATION, Figure 12. River near Mehlville, Missouri (structures A-1850 and A-4936). River Channel-Bed Monitor Uncertainty and Limitations 25 FEET 500 METERS 400 100 300 200 50 100 25 Bedforms 0 0 90°16'30" Bedforms 356 to 358 354 to 356 352 to 354 350 to 352 348 to 350 346 to 348 344 to 346 342 to 344 340 to 342 338 to 340 336 to 338 334 to 336 332 to 334 330 to 332 328 to 330 326 to 328 324 to 326 322 to 324 320 to 322 July 8, 2009                    38°29'20" 38°29'10" 394 to 396 392 to 394 390 to 392 388 to 390 386 to 388 384 to 386 382 to 384 380 to 382 378 to 380 376 to 378 374 to 376 372 to 374 370 to 372 368 to 370 366 to 368 364 to 366 362 to 364 360 to 362 358 to 360                    Channel-bed elevation, in feet above North American Vertical Datum of 1988 EXPLANATION Bedforms Vicinity of pier 12 Vicinity 90°16'30" Direction of flow May 13, 2009 Location of pier 12 90°16'30" 38°29'20" 38°29'10" 90°16'30" Bathymetric surveys conducted October 2, 2008, October 2, 2008

Figure 13. May 13, 2009, and July 8, using multibeam sonar at the Mississippi River near Mehlville, Missouri (structures A-1850 and A-4936). 38°29'20" 38°29'10" 26 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09 rod was positioned at the side of the transducer, as opposed the Mississippi River during the latter part of December to obtaining a depth directly underneath the head, which 2008 into the middle of January 2009 affected the RCBM at may have contributed a small amount of additional error. the upstream nose. A voltmeter, used to conduct a continu- Referring to the specifications mentioned earlier and physi- ity check in the shielded cable through the transducer head, cal measurements made during the period of data collection indicated a closed circuit. In addition, diagnostics of the DCP for both Chariton River sites, the monitored channel bottom and wiring did not provide any more evidence of why no was typically within 0.5 foot of the physical measurement data were being received. Although a field inspection indi- and never varied more than 1 foot of the true value during cated no damage near the water surface, the transducer head substantial hydrologic events. For the Mississippi River loca- needed to be examined and was not serviceable because of tion, coincident bathymetric surveys were compared with high river stage throughout the data collection period. Unlike the channel-bed measurement from the RCBM. Referring to the monitor at the upstream nose which reported only 68 figure 11, bathymetric surveys occurring May 13 and July days (37 percent of the data collection period), channel-bed 8, 2009, depicted channel-bed elevations at the downstream record on the downstream nose was continuous throughout nose that correlated well (within 0.5 foot) with RCBM mea- the 182-day data collection period. surements. Data from a prior bathymetric survey on October 2, 2008 appeared reasonable at the upstream nose consider- ing the channel-bed record of the RCBM did not begin until October 24, 2008 (fig. 12). However, assuming a flat channel Summary and Conclusions bottom at the upstream and downstream nose, channel-bed record from RCBMs at the Mississippi River location have A single-beam sonar technology, used primarily for approximately 7 percent error due to the angle in which the marine applications, was adopted as a river channel-bed moni- transducer head was mounted and the signal interface with tor (RCBM) to evaluate channel-bed behavior in response to the channel bottom. Depth measurements did not take into hydrologic conditions at two locations crossing the Chariton account the angle of the installation; therefore, relative dis- River and one location crossing the Mississippi River. The TM tortions of bedforms or scour holes could be biased high as RCBM used for this data collection effort utilized Smart much as 7 percent. sensor technology, a technology composed of active electron- Challenges in adopting use of single-beam sonar tech- ics in the transducer head allowing function of the transducer nology are primarily location and environmental factors. The element as well as signal processing. The RCBM was inte- location of the RCBM needs to be in a pool with sufficient grated with an existing streamgage data collection platform depth at a base-flow condition so that during hydrologic that collected readings every 15 minutes and transmitted events, the deposition of sediment does not accumulate too hourly. As a result of historically documented channel-bed close to the transducer head and cause excessive noise and changes, an initial location crossing the Chariton River near additional echo returns as discussed in the river channel-bed Prairie Hill (structure L-344) was chosen as a pilot study for monitor results section. For periods when channel-bed data nearly a year until additional sites crossing the Chariton River are indicating noise from shallow monitoring, more frequent at Novinger (structure L-534) and the Mississippi River near field inspections are needed to help smooth and estimate data Mehlville (structures A-1850 and A-4936) were monitored by during periods of excessive noise. Environmental factors, such the U.S. Geological Survey in cooperation with the Missouri as ice accumulation and floating debris, are potential concerns Department of Transportation. Bed elevation data for the that may cause periods of missing record. A proper design can Chariton River at Novinger and the Mississippi River near mitigate damage as well as accumulation from floating ice and Mehlville were provided to the World Wide Web for real-time debris; however, the reliability of the RCBM can be affected monitoring. during occasions where ice and debris collect at depths below With the exception of ice on the transducer head, noise the transducer head. generated from shallow depth monitoring and brief equip- Overall, the Chariton River installations had minor ment power failure, both Chariton River locations provided limitations in providing continuous channel-bed record. The continuous channel-bed record that demonstrated responses Chariton River near Prairie Hill (structure L-344) had 39 to hydrologic events. At both locations, the presence of days of missing record out of 730 days, or about 5 percent. bedforms was identifiable during inter-event flows, which Although footing exposure was evident for both monitors may have provided an additive effect in the evaluation of the at the Chariton River at Novinger (structure L-534), neither scour and deposition in relation to known hydrologic events. monitor had any missing record over the period of 457 days. At the Chariton River near Prairie Hill (structure L-344), an The Mississippi River near Mehlville (structures A-1850 RCBM was installed on the downstream side of the upstream and A-4936) location presented challenges during the instal- column of pier 4. During data collection from August 21, lation of RCBMs; specifically, ensuring adequate depths of 2007, through August 21, 2009, the channel-bed scoured as the transducer head and sufficient clearance of the acoustic much as 13 feet from a period of record (78 years) peak flood signal over the footer and seal course to the channel bot- event of 38,400 cubic feet per second that occurred on July tom. The frequency and magnitude of ice accumulation on 27, 2008, and had an annual exceedence probability within 0.2 References Cited 27 to 1 percent (500- and 100-year recurrence). At the Chariton Becker, L.D., 1994, Investigation of bridge scour at selected River at Novinger (structure L-534), RCBM’s were installed sites on Missouri streams: U.S. Geological Survey Water- on the downstream side of the upstream and downstream col- Resources Investigations Report 94–4200, 40 p. umns of pier 7. The initial offset had to be extended horizon- tally at the downstream column in late June as a result of an Huizinga, R.J., and Rydlund, P.H., Jr., 2004, Potential-scour exposed footer depicting a steady and flat representation of the assessments and estimates of scour depth using different channel bottom. The RCBM at the upstream column had to be techniques at selected bridge sites in Missouri: U.S. Geo- extended horizontally in late October because this footer pro- logical Survey Scientific Investigations Report 2004–5213, gressively became more exposed. Channel-bed record at both 42 p. columns reflected as much as 3 to 5 feet of scouring as a result of hydrologic events occurring December 22, 2008, March Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial 8, March 24, April 27, and May 16, 2009, as well as a subtle processes in geomorphology: San Francisco, Calif., W.H. time lag between event-related scouring from the upstream to Freeman and Company, 522 p. downstream monitoring locations. RCBM’s also were installed at the Mississippi River near Missouri Division of Geology and Land Survey, 1979, Mehlville (structures A-1850 and A-4936) on the upstream and Geologic map of Missouri: Rolla, Missouri Department of downstream nose of pier 12. As a result of the complexity of Natural Resources, scale 1:500,000. the foundation of pier 12, the transducer head was positioned at a 22 degree departure from vertical to avoid interference Missouri Department of Transportation, 1977, Plans for from the footer and seal course when sounding the channel proposed Federal Aid Interstate Highway Bridge over Mis- bottom. The upstream monitoring location documented chan- sissippi River, Jefferson Barracks, Missouri: Jefferson City, nel-bed changes less than 1.5 foot over a 68-day period of data Missouri State Highway Department, F.A.I. Route 270 Proj- collection before suspected damage at the upstream monitor. ect EACI–1–270–9(1)84, Bridge Nos. A-1850 and A-4936. The downstream monitoring location documented channel- bed changes as large as 5 feet over a 182-day period of data Mueller, D.S., Landers, M.N., and Fischer, E.F., 1995, Scour collection. Bedforms that were documented in bathymetric measurements at bridge sites during 1993 Upper Missis- surveys using multibeam sonar on May 13 and July 8, 2009, sippi River Basin flood: Transportation Research Record indicated potential correlation to bedform movement observed No. 1,483, p. 47–55. June 7 through June 14, June 27 through June 30, and August National Oceanic and Atmospheric Administration, 2009, 6 through August 23, 2009, as documented from the RCBM at the downstream nose. Coastal Services Center: Remote sensing for coastal man- Based on manufacturing specifications and independent agement, accessed data August 25, 2009, at http://www.csc. depth measurements, the monitored channel bottom was typi- noaa.gov/crs/rs_apps/sensors/multi_beam.htm cally within 0.5 foot of the physical measurement and never Pittaluga, B.M., Maffei, M., and Seminara, G., 2004, The varied more than 1 foot during substantial hydrologic events at effect of migrating bedforms on local scour around bridge both Chariton River locations. For the Mississippi River loca- tion, depth measurements did not account for the 22 degree piers, in Greco, M., Carravetta, A., and Della Morte, R., installation angle of the RCBM, required to provide adequate eds., River flow 2004: International Conference on Fluvial clearance to the channel bottom. Based on the 22 degree angle, Hydraulics, 2d, Napoli, Italy, 2004, Proceedings: London, relative distortions of bedforms or scour holes could be biased England, Taylor and Francis Group, v. 2, p. 575–584. high as much as 7 percent. Raisz, E., 1957, Landforms of the United States physiographic map, in Pirkle, E.C., Yoho, W.H., Henry, J.A., eds., Natural landscapes of the United States (4th ed.): Dubuque, , References Cited Kendall/Hunt Publishing Company, 411 p.

Airmar Technology Corporation, 2006, Theory of operations Richardson, E.V., and Davis, S.R., 2001, Evaluating scour at manual: Milford, N.H., 24 p. bridges (4th ed.): U.S. Federal Highway Administration Publication FHWA NHI 01–001 Hydraulic Engineering Bartholoma, S.D., Kolva, J.R., and Nielsen, J.P., 2003, User’s Circular no. 18, 378 p. manual for the National Water Information System of the U.S. Geological Survey Automated Data Processing Sys- U.S. Geological Survey, 2009, Overview of satellite data tem (ADAPS): U.S. Geological Survey Open-File Report collection system, accessed data August 25, 2009, at http:// 2003–123, version 4.3, 407 p. wa.water.usgs.gov/data/realtime/realtime_view.html. 28 Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09

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For more information concerning this publication, contact: Director, USGS Missouri Water Science Center 1400 Independence Road Rolla, MO 65401 (573) 308–3667

Or visit the Missouri Water Science Center Web site at: http://mo.water.usgs.gov References Cited 29 Rydlund—Real-Time River Channel-Bed Monitoring at the Chariton and Mississippi Rivers in Missouri, 2007–09—Scientific Investigations Report 2009–5254