15_USIBWC LRGFCP Hydraulic Model Report 200306.pdf

HYDRAULIC MODEL OF THE RIO GRANDE AND FLOODWAYS

WITHIN THE

LOWER RIO GRANDE FLOOD CONTROL PROJECT

JUNE 2003

Prepared by:

INTERNATIONAL BOUNDARY AND WATER COMMISSION

UNITED STATES AND MEXICO

UNITED STATES SECTION

TABLE OF CONTENTS

A. INTRODUCTION 1

B. PURPOSE OF THE STUDY 2

C. PRESENT OPERATION OF THE LRGFCP

1. DEVELOPMENT OF THE PROJECT 3

2. DISTRIBUTION OF DESIGN FLOOD FLOW 4

D. OVERVIEW OF THE 1992 HYDRAULIC MODEL

1. EVENTS LEADING TO THE STUDY 6

2. DESCRIPTION OF THE 1992 MODEL 7

3. CONCLUSIONS FROM THE 1992 MODEL 7

E. THE 2003 HYDRAULIC MODEL

1. BACKGROUND 8

2. DESCRIPTION OF THE 2003 MODEL 8

3. MODEL RUNS 9

4. RESULTS 10

5. CONCLUSIONS 11

LIST OF TABLES

TABLE 1 HYDRAULIC MODEL RUN RESULTS FOR RIO GRANDE

FROM PEÑITAS TO BELOW BROWNSVILLE 13

TABLE 2 HYDRAULIC MODEL RUN RESULTS FOR MAIN AND

NORTH FLOODWAYS 19

TABLE 3 HYDRAULIC MODEL RUN RESULTS FOR

ARROYO COLORADO 26

LIST OF FIGURES

FIGURE 1 LOWER RIO GRANDE VALLEY 5

FIGURE 2 FLOOD PROFILE ON THE RIO GRANDE FROM PEÑITAS TO

BELOW BROWNSVILLE RESULTING FROM 250,000 CFS FLOOD

ON RIO GRANDE AT RIO GRANDE CITY 32

FIGURE 3 FLOOD PROFILE ON THE U.S. MAIN AND NORTH FLOODWAYS

OF THE RIO GRANDE RESULTING FROM 250,000 CFS FLOOD

ON RIO GRANDE AT RIO GRANDE CITY 33

FIGURE 4 FLOOD PROFILE ON THE ARROYO COLORADO FLOODWAY

OF THE RIO GRANDE RESULTING FROM 250,000 CFS FLOOD

ON RIO GRANDE AT RIO GRANDE CITY 34

FIGURE 5 RIO GRANDE LEVEE ELEVATIONS WITH RESPECT TO WATER

SURFACE ELEVATIONS 35

FIGURE 6 MAIN AND NORTH FLOODWAY LEVEE ELEVATIONS WITH

RESPECT TO WATER SURFACE ELEVATIONS 36

FIGURE 7 ARROYO COLORADO LEVEE OR HIGH BANK ELEVATIONS

WITH RESPECT TO WATER SURFACE ELEVATIONS 37

FIGURE 8 FLOOD PROFILES ON THE RIO GRANDE FROM PEÑITAS TO

BELOW BROWNSVILLE RESULTING FROM 250,000 CFS FLOOD

ON RIO GRANDE AT RIO GRANDE CITY 38

A. INTRODUCTION

The present report deals with a hydraulic modeling study of the Lower Rio Grande Flood Control Project (LRGFCP) under the occurrence of the design flood flows in the river channel and its floodways within the United States. A similar study was conducted and a report entitled “Status of Conveying Capacity of the Lower Rio Grande Flood Control Project” issued in 1992.

Since then, changes have occurred in land use and agricultural practices within the LRGFCP, and additional structures have been constructed, creating influences on the flow that were not present for the 1992 study. Also, additional geometrical data have been collected, and software capabilities have been enhanced, adding reliability to the results of the hydraulic model. The reader is directed to the 1992 report cited above for a comprehensive coverage of the history, physical characteristics, and development of the LRGFCP.

B. PURPOSE OF THE STUDY

The purpose of the present study is to determine the capability of the LRGFCP to convey the design flood flows, under existing vegetation conditions, at water surface elevations that will not encroach on the proposed 3 ft freeboard for the Rio Grande levees and 2 ft. freeboard for the floodway levees. The occurrence of such encroachment at any point would indicate a diminished capability of the LRGFCP to provide adequate flood protection at that point.

C. PRESENT OPERATION OF THE LRGFCP

1. DEVELOPMENT OF THE PROJECT

The LRGFCP was constructed under an agreement between the United States and Mexico concluded in 1932. Under that agreement, the two countries adopted a flood control plan for the lower Rio Grande prepared by the International Boundary Commission (IBC), and by which each Government committed to construct river levees and off- river floodways in its territory based on a design flood of 187,000 cubic feet per second (cfs) (5,300 cubic meters per second (cms)) at Peñitas. Later the 1944 Water Treaty renamed the IBC as the International Boundary and Water Commission (IBWC), and assigned to it the construction and operation and maintenance of flood control works in the Rio Grande/Rio Bravo. The 1944 Water Treaty also removed a prohibition for construction of dams on the Rio Grande. Pursuant to this action, the IBWC, under Minute No. 196 signed in December 1950, constructed the Anzalduas Dam diversion structure upstream of the Hidalgo/Reynosa area.

In 1967, the LRGFCP was subjected to a flood flow of 220,000 cfs (6,230 cms) at Rio Grande City, resulting from rainfall associated with Hurricane Beulah. Due to extensive flooding from this event, in 1970 the United States and Mexico, in Minute No. 238, agreed to construct improvements to the project on the basis of a design flood of 250,000 cfs (7,080 cms) at Rio Grande City. These included improvements to the interior floodway system in each country, clearing of the river channel in the Brownsville/Matamoros area, and construction of the Retamal Dam diversion structure. After construction of these various stages of improvements, at present the project consists of the following features:

$ The reach of the Rio Grande from just upstream of Peñitas at River Mile 186 to downstream of Brownsville at River Mile 28, including levees on both sides of the river and two diversion dams, the Anzalduas Dam at River Mile 169.4 and the Retamal Dam at River Mile 129.22.

$ In the United States, the Main Floodway from just upstream of Anzalduas Dam to the vicinity of Mercedes where it branches off into the North Floodway and the Arroyo Colorado, both of which end at the Gulf of Mexico.

$ In Mexico, the Mexican Floodway from just upstream of Retamal Dam to the Gulf of

Mexico.

A map of the LRGFC including the features described above and other upstream features is shown in Figure 1.

2. DISTRIBUTION OF DESIGN FLOOD FLOW

As mentioned previously, in Minute No. 238, the IBWC adopted a design flood of 250,000 cfs (7,080 cms) at Rio Grande City. This design flood was used as the basis for design of the proposed improvements and is the basis for operation of the flood control works in accordance with the distribution of flows agreed in Minute No. 238 by the Governments of the United States and Mexico, and which is as follows:

$ Rio Grande at Rio Grande City 250,000 cfs 7,080 cms $ Reduction of flow due to channel storage between

Rio Grande City and Peñitas 15,000 cfs 430 cms $ Rio Grande at Peñitas 235,000 cfs 6,650 cms $ Diversion to the Main Floodway in the United States 105,000 cfs 2,970 cms $ Rio Grande at Hidalgo/Reynosa 130,000 cfs 3,680 cms $ Reduction of flow due to channel storage between Hidalgo/Reynosa and above Retamal Dam 5,000 cfs 140 cms $ Diversion to the Mexican Floodway 105,000 cfs 2,970 cms $ Rio Grande at Brownsville/Matamoros 20,000 cfs 570 cms

Details on operation of the off-river floodway system in each country are not part of Minute No.

238. In the United States, it is proposed that the flow of 105,000 cfs (2,970 cms) diverted into the Main Floodway be distributed as 84,000 cfs (2,380 cms) to the North Floodway and 21,000 cfs (590 cms) to the Arroyo Colorado.

D. OVERVIEW OF THE 1992 HYDRAULIC MODEL

1. EVENTS LEADING TO THE STUDY

During September and October 1958, flood flows occurred in the LRGFCP with a peak discharge of 104,000 cfs (2,945 cms) at Rio Grande City that caused extensive damage to farming areas in the Lower Rio Grande Valley. It became obvious that the flood conveyance capacity of the LRGFCP had been reduced and was inadequate. It was determined that the reduction in capacity was mainly due to the growth of vegetation in the channel and floodplain.

Also, review of channel configurations indicated that their geometry had been changed resulting in reduced conveyance capacity.

To restore the conveyance capacity of the LRGFCP, the Governments of the United States and Mexico agreed in Minute No. 212, signed in December 1961, to a vegetation clearing program in both countries. The agreement was to clear vegetation from the edge of the water to the top of the channel bank or to a point 330 feet (100 meters) from the edge of the water, whichever was the shorter distance. This clearing would extend along the banks of the Rio Grande channel from Anzalduas Dam to below Brownsville/Matamoros. Clearing work as agreed in Minute No. 212 was started in 1962 and completed before the 1967 flood season. Later, the vegetation management practice in the United States was changed to clearing vegetation from selected banks in a 34.5 mile (55.5 kilometer) reach from upstream of Brownsville to downstream of this area.

In November 1989, the U.S. Section of the IBWC (USIBWC) was sued in connection with its vegetation management practices, in a civil action in which the plaintiffs alleged violations by USIBWC of the Endangered Species Act and the National Environmental Policy Act. As a result of this action, the Court issued a Consent Decree requiring USIBWC to enter into formal consultation with the U.S. Fish and Wildlife Service (USFWS). The Consent Decree also required USIBWC to prepare an Environmental Impact Statement (EIS) that would specifically address vegetation maintenance practices in the LRGFCP.

In late 1990 USIBWC initiated the Section 7 consultation process, whereby USIBWC was directed to prepare a Biological Assessment for vegetation clearing activities. In early 1993, USIBWC submitted the Biological Assessment to USFWS, and discussions between the two agencies followed to agree on a vegetation management plan. In mid-1993, USFWS issued a Biological Opinion that called for the creation of a 33 ft. (10 meters) wide, heavily vegetated wildlife travel corridor, adjacent to a 75 ft. (23 meters ) strip of land in which USIBWC would be allowed to mow, and which would be next to the water edge, in the reach of the Rio Grande from River Mile 28 to River Mile 62.5. It was in connection with the determination of the effects of this vegetation management plan on flood flows that the 1992 study was prepared.

2. DESCRIPTION OF THE 1992 MODEL

The 1992 hydraulic modeling study of flood flows in the LRGFCP was prepared with the Hydrologic Engineering Center HEC-2 software. The study contains two models, both for the same design flood of 250,000 cfs (7,080 cms) at Rio Grande City and with identical geometrical data, but with different roughness coefficients in areas where vegetation management would be different. One model is based on vegetation existing in 1988, and calibrated to the Hurricane Gilbert flows in the Rio Grande. The second model is based on a full growth vegetation condition, i.e., including full vegetation in a 33 ft. (10 meters) wildlife travel corridor, as indicated in the USFWS Biological Opinion.

3. CONCLUSIONS FROM THE 1992 MODEL

The general conclusion reached from the 1992 modeling study was that the LRGFCP is not capable of providing adequate design flood protection. It is noted here, in order to give a more complete sense of this conclusion, that approximately 70% of the length of the United States river levee provides adequate design flood protection against levee overtopping, in that there is no encroachment of the 3 ft. (0.9 meters) freeboard.

Other conclusions reached from the 1992 model are:

$ The United States river levee will be overtopped at spot locations from just upstream of

Hidalgo/Reynosa Bridge # 1 to downstream of the Santa Ana Refuge.

$ About 30 noncontiguous miles (48 kilometers) of the United States levee have less than the recommended 3 ft. (0.9 meters) of freeboard.

$ The river levee in Mexico is overtopped in at least 35 noncontiguous miles (56 kilometers), including reaches in areas adjacent to Reynosa and Matamoros.

E. THE 2003 HYDRAULIC MODEL

1. BACKGROUND

As stated previously, the Consent Decree issued pursuant to the 1989 civil action suit against USIBWC stipulated that the USIBWC should prepare an EIS specifically addressing its vegetation maintenance activities in the LRGFCP. To this end, the USIBWC entered into an agreement with the U.S. Army Corps of Engineers (USACOE) for them to prepare the required EIS. At present, a draft EIS has been delivered to and reviewed by the USIBWC. Preparation of the final EIS is awaiting resolution of various issues.

As part of the studies needed for the EIS, a hydraulic modeling study was conducted in which several alternatives were considered for vegetation management. A HEC-2 model of the Rio Grande within the LRGFCP was run for each of the alternatives, with cross section geometry and flows being identical for all the alternatives. Cross section geometry data were taken from the 1992 model, except in a reach 10.2 miles (16.4 kilometers) long in the Brownsville/Matamoros area where the United States and Mexico agreed to move the levees in and establish a Restricted Use Zone (RUZ) for the floodplains on both sides of the Rio Grande. Also, the Los Tomates and Pharr bridges, which had not been built at the time the 1992 model study was conducted, were added. Roughness coefficient values in each alternative were assigned in accordance with the current or planned vegetation management scheme, as applicable. For alternatives that involved current vegetation conditions, aerial photography of the LRGFCP taken in 1996 and 1999 was used to assess vegetation density and height.

A Hydraulic Modeling Report was delivered by USACOE to USIBWC in October 2001 containing descriptions of the various alternatives and results of the modeling study. The different alternatives were assessed in terms of the effects of the vegetation maintenance scheme on water surface elevations. Water surface profiles were compared to top of levee profiles to assess the severity of overtopping in terms of length of levee overtopped and average height of overtopping.

2. DESCRIPTION OF THE 2003 MODEL

The 2003 LRGFCP hydraulic model is based on the geometrical cross section data used in the 1992 model for the channel of the Rio Grande and the floodways in the United States. The Rio Grande data are modified from the 1992 model for the RUZ and additional bridges described earlier, and to include data for 24 additional new cross sections that were recently surveyed. The locations of the cross sections from the 1992 model and the new cross sections for the Rio Grande, the Main and North Floodways and the Arroyo Colorado are shown in Appendix A, Appendix B and Appendix C, respectively. For the Rio Grande component, the 2003 model uses roughness coefficient values as determined for the EIS Hydraulic Modeling Report alternative referred to as the Current Maintenance - A model alternative. This is a model with roughness coefficient values determined from presently existing vegetation, and a plan to control vegetation growth in areas of the floodplain outside of the wildlife travel corridor. As mentioned earlier, aerial photography taken in 1996 and 1999 was used to assess existing vegetation conditions.

For the off-river floodways in the United States, roughness coefficient values are identical to those in the 1992 model. Geometrical data for all cross sections, roughness coefficient values, and geometrical and modeling approach data for bridges and in- line weirs are given in the appendices.

Flood flows in the 2003 model for all components of the project are as per the IBWC Minute No.

238 agreed flow distribution. The actual flow distribution of flows may be affected by existing friction and structural controls, as well as by any future changes in these. Determination of any deviations from the Minute No. 238 flow distribution and any proposed improvements that would minimize these deviations are not within the scope of the present study.

The 2003 model was prepared using the recent Hydrologic Engineering Center HEC-RAS software, version 3.0. Since the model for the Current Maintenance - A alternative is in HEC-2, it was necessary to go through a data conversion process, which is performed within the HEC- RAS program. Bridge data needed to be manually input to be properly interpreted in the HEC- RAS format. Also, Anzalduas Dam and Retamal Dam were manually converted from the bridge designation in HEC-2 to an in- line weir designation in HEC-RAS. For the off-river floodways, the data were converted directly from the 1992 model to the HEC-RAS format. For these components, it was also necessary to edit the bridge data manually for proper inclusion in the HEC-RAS model.

3. MODEL RUNS

The present modeling consisted of one model run for each of the LRGFCP components, i.e., the Rio Grande, the Main and North Floodways as one continuous conveyance, and the Arroyo Colorado as a branch of the Main Floodway. The vegetation condition in all components is as presently existing, with additional vegetation growth expected only in the wildlife travel corridor between River Mile 28 and River Mile 62.5 of the Rio Grande. As mentioned previously, the flows used for each component are as specified in IBWC Minute No. 238.

4. RESULTS

Results found from the HEC-RAS model runs are shown in Table 1 for the Rio Grande, Table 2 for the Main and North Floodways, and Table 3 for the Arroyo Colorado. The water surface elevation profiles are graphically shown and compared to the top of levee or high bank profiles in Figure 2 for the Rio Grande, Figure 3 for the Main and North Floodways, and Figure 4 for the Arroyo Colorado. From the graphical presentations, it can be established that the water surface profiles overtop the levee or high bank profiles of all three components at various points along each profile.

For a better graphical depiction of levee overtopping or encroachment on freeboard in the Rio Grande and the floodways, the difference between the top of levee elevation or high bank elevation and the water surface elevation was calculated at each cross section and plotted as (Levee or High Bank Elevation - Water Surface Elevation) vs. channel distance. The plots are shown in Figure 5 for the Rio Grande, Figure 6 for the Main and North Floodways, and Figure 7 for the Arroyo Colorado. It can be readily determined that any point that plots below the 0 line indicates a point of levee or high bank overtopping, and any point that plots below the +3 ft.

(+0.9 meters) line in the Rio Grande graph and the +2ft. line in the Main and North Floodways graph indicates a point of encroachment of the proposed 3 ft. (0.9 meters) freeboard for the Rio Grande and 2 ft. freeboard for the floodways.

A comparison was also made between the resulting water surface profile from the HEC-RAS 2003 model and the profiles from the HEC-2 1992 models with 1988 vegetation and with vegetation at mature growth in the full length of the project. Graphical results are presented as water surface profiles from each model in Figure 8. It may be seen that in the lower reach of the Rio Grande between River Mile 28 and River Mile 62.5 the 1992 model with vegetation at mature growth yields higher water surface elevations than the 2003 model. This is attributable to the present condition of vegetation in this reach, as considered in the 2003 model, which is not at mature growth. Upstream of River Mile 62.5, the differences in these two profiles become smaller, since present vegetation is mostly near mature growth. The profile for the 1992 model with 1988 vegetation is between one and two feet lower than the 2003 model profile, except for a reach between River Miles 48 and 62. Also, differences in water surface elevations are introduced at the Retamal and Anzalduas dams. These result from the improved weir modeling techniques available in the HEC-RAS software.

5. CONCLUSIONS

From a point of view of flood risk generated from encroachment on the recommended 3ft. (0.9 meters) levee freeboard in the Rio Grande, it is concluded that in general the LRGFCP does not provide adequate flood risk protection along its full length for the 100-year flood of 250,000 cfs (7,080 cms) at Rio Grande City. Close examination of the results presented as noted above indicates the following:

$ In the Rio Grande, the United States levee would be overtopped along 38 river miles (61 river kilometers). This overtopping would occur in about two thirds of the levee length upstream of Anzalduas Dam, and in most of the length downstream of Anzalduas Dam to the Santa Ana National Wildlife Refuge.

$ In the Rio Grande, the United States levee would be subject to encroachment of the proposed 3 ft. (0.9 meters) freeboard along 64 river miles (103 river kilometers). This encroachment would occur mostly between Peñitas and the Santa Ana National Wildlife Refuge, about 6 miles (10 kilometers) between the Los Indios Bridge and above Brownsville, and 2 miles (3 kilometers) of the Amigoland levee in Brownsville.

$ In the Rio Grande, the Mexican levee would be overtopped along 57 river miles (92 river kilometers). The overtopping would occur along 38 river miles (61 river kilometers) between Peñitas and Retamal Dam and 19 river miles ( 31 river kilometers) between the Los Indios Bridge and above Matamoros.

$ In the Rio Grande, the Mexican levee would be subject to encroachment of a 3 ft. (0.9 meters) freeboard along 110 river miles (177 river kilometers). This encroachment would occur from Peñitas to below Retamal Dam, except for short distances in between, and from above Los Indios Bridge to Matamoros.

$ In the Main and North Floodways, the left levee would be overtopped along 1 mile (1.6 kilometers), and encroachment on the 2 ft. (0.6 meters) freeboard would occur along 10 miles (16 kilometers).

$ In the Main and North Floodways, the right levee would be overtopped along 1 mile (1.6 kilometers), and encroachment on the 2 ft. (0.6 meters) freeboard would occur along 14 miles (23 kilometers).

From examination of the Rio Grande profile and the Main Floodway profile in the vicinity of the Banker Weir, it is also concluded that under the design flood, the diversion into the Main Floodway will be more than the 105,000 cfs (2,970 cms) stipulated in IBWC Minute No. 238.

Improvements that may be proposed to control the amount of flow into the Main Floodway would require further study.

For flows into the Mexican Floodway, study of the water surface profile along the floodway resulting from a diversion of 105,000 cfs (2,970 cms) would be required before a conclusion can be reached on whether or not this would be the actual diverted flow under the design flood.

TABLE 1

HYDRAULIC MODEL RUN RESULTS FOR

RIO GRANDE FROM PEÑITAS TO BELOW BROWNSVILLE

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

186 235000 86.30 134.37 0.000061 4.42 176597 10519 0.13

184 235000 87.00 133.87 0.000115 5.78 141934 10727 0.17

182.4 235000 79.50 133.04 133.18 0.000061 5.72 206859 15361 0.16

180.3 235000 87.40 131.95 132.28 0.000112 7.37 144918 9709 0.21

178.5 235000 87.00 130.71 131.04 0.000122 7.43 157801 11045 0.22

176.8 235000 89.20 129.39 129.90 0.000184 8.12 138303 8702 0.25

174.6 235000 86.50 128.00 (ft) 0.000098 8.55 162410 10078 0.25

171.8 235000 75.60 126.92 134.47 0.000142 6.09 118054 8410 0.18

170.5 235000 74.60 123.32 134.04 0.000436 15.24 70671 4870 0.47

170.02 235000 90.00 121.71 124.45 0.000277 15.62 74840 4865 0.49

169.83 130000 90.00 122.40 123.78 0.000174 11.15 68748 4500 0.35

169.14 130000 85.00 122.51 97.41 123.19 0.000042 6.61 19751 624 0.19

169.13 Inline Weir

169.12 130000 72.50 122.51 122.89 0.000017 4.96 26193 524 0.12

169.1 130000 84.00 122.42 122.87 0.000027 5.41 24026 659 0.16

168.85 130000 72.00 122.24 122.80 0.000360 6.11 25423 1070 0.17

168.3 130000 75.70 121.01 121.36 0.000613 5.22 41066 2238 0.16

167.4 130000 74.50 119.19 119.45 0.000169 5.12 85618 8740 0.15

166.6 130000 71.70 118.81 118.90 0.000073 3.97 163080 12700 0.11

161.4 130000 70.50 117.49 117.59 0.000093 3.74 150236 14947 0.11

157.15 130000 70.00 113.49 114.20 0.000230 7.53 36055 2402 0.22

156.93 125000 57.50 112.90 81.16 113.75 0.000180 7.51 19299 541 0.19

156.915 Bridge

156.9 125000 57.50 112.40 113.22 0.000179 7.43 19029 541 0.19

156.87 125000 61.40 112.44 80.46 113.13 0.000083 7.01 24704 820 0.18

156.855 Bridge

156.84 125000 61.40 112.34 113.07 0.000088 7.17 24621 820 0.18

156.6 125000 61.30 112.25 112.91 0.000194 7.15 28470 2183 0.19

155.7 125000 69.00 111.88 112.04 0.000152 4.58 75870 7548 0.14

155.01 125000 67.30 110.96 111.17 0.000442 4.75 52391 4518 0.16

154.6 125000 56.00 109.52 110.07 0.000376 6.15 27510 1354 0.18

153.85 125000 66.80 107.96 108.52 0.000608 6.96 35912 3718 0.23

153.36 125000 67.30 107.40 107.51 0.000172 4.01 102662 14344 0.13

RIO GRANDE FROM PEÑITAS TO BELOW BROWNSVILLE

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

152.53 125000 67.00 106.70 106.76 0.000171 125000 67.00 106.70

151.7 125000 65.40 106.01 106.07 0.000134 3.26 123108 14131 0.11

151.27 125000 66.24 105.76 90.14 105.79 0.000061 2.33 136258 14891 0.08

151.255 Bridge

151.25 125000 66.24 105.75 105.78 0.000057 2.25 136118 14891 0.08

151.24 125000 66.24 105.75 105.78 0.000061 2.33 136072 14891 0.08

150.31 125000 65.00 105.32 105.37 0.000146 3.14 130193 17215 0.11

147.68 125000 60.40 104.45 104.49 0.000142 2.39 135289 15507 0.09

145 125000 61.20 102.81 102.86 0.000088 3.14 148495 14110 0.10

144.55 125000 59.00 102.62 102.66 0.000088 2.95 146419 14238 0.09

142.5 125000 57.30 101.33 101.43 0.000178 4.28 143818 13900 0.14

140.74 125000 58.10 100.06 100.10 0.000068 3.15 143291 13786 0.10

139.85 125000 60.00 99.34 99.53 0.000152 5.24 96286 11871 0.16

139.01 125000 59.80 98.83 98.90 0.000119 3.36 93649 10391 0.11

137.71 125000 57.00 98.04 98.09 0.000124 2.99 101177 10188 0.10

135 125000 58.30 96.23 96.30 0.000113 3.70 103660 10240 0.12

132.75 125000 53.90 94.28 94.56 0.000185 6.50 88900 8687 0.20

131.35 125000 55.60 92.88 93.01 0.000211 4.81 86016 8598 0.15

130.51 125000 55.50 91.70 92.01 0.000243 6.27 51218 4416 0.20

129.3 20000 55.50 91.65 91.66 0.000008 1.02 44678 4170 0.03

129.23 20000 55.50 91.55 91.62 0.000039 2.20 9118 309 0.07

129.22 20000 55.50 91.55 91.62 0.000039 2.20 9117 309 0.07

129.216 20000 56.00 90.84 68.27 91.55 0.000096 6.86 3083 162 0.20

129.215 Inline Weir

129.214 20000 56.00 84.12 85.29 0.000180 8.67 2306 82 0.29

129.213 20000 56.00 82.81 85.06 0.001012 12.03 1662 62 0.41

129.212 20000 56.00 82.78 85.03 0.001015 12.05 1660 62 0.41

129.211 20000 56.00 83.83 83.97 0.000016 3.05 6556 299 0.11

129.21 20000 56.00 83.84 83.95 0.000013 2.73 7338 327 0.10

129.2 20000 55.40 83.83 83.94 0.000175 2.67 8269 776 0.11

129.03 20000 54.20 83.63 83.72 0.000196 2.54 8534 1400 0.11

127.7 20000 50.30 82.67 82.71 0.000093 1.84 23139 6875 0.08

126.7 20000 51.30 82.06 82.14 0.000183 2.59 21128 9461 0.11

125 20000 50.60 80.86 80.97 0.000102 2.86 15509 5309 0.10

123.8 20000 50.10 79.89 79.99 0.000132 2.65 11641 2551 0.10

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

122.5 20000 52.30 79.06 79.20 0.000100 3.05 7778 577 0.11

121.46 20000 45.80 78.66 78.81 0.000117 3.38 9381 1062 0.12

120.7 20000 51.20 78.23 78.34 0.000129 2.67 8691 844 0.11

120.62 20000 46.90 78.14 58.49 78.27 0.000151 2.91 7432 615 0.11

120.605 Bridge

120.59 20000 46.90 78.13 78.26 0.000151 2.91 7427 615 0.11

120.5 20000 50.20 78.07 78.17 0.000096 2.61 10958 1286 0.10

120.38 20000 52.00 77.75 77.81 0.000081 2.33 23457 3648 0.09

117.87 20000 49.70 76.61 76.71 0.000114 2.87 21571 5098 0.11

117.2 20000 47.20 76.10 76.24 0.000141 3.09 12093 3842 0.12

116.5 20000 47.90 75.73 75.91 0.000113 3.42 8744 1576 0.13

116.1 20000 46.20 75.49 75.62 0.000124 2.97 7602 478 0.12

115.7 20000 48.50 75.24 75.39 0.000111 3.23 8022 1346 0.12

115 20000 36.50 74.73 74.88 0.000162 3.24 8864 1477 0.12

114.8 20000 47.30 74.47 74.63 0.000121 3.34 9649 1578 0.13

114.65 20000 42.90 74.44 74.53 0.000107 2.53 12265 2287 0.10

114.1 20000 42.40 73.85 73.92 0.000185 2.28 19451 9145 0.10

112.2 20000 41.20 72.40 72.51 0.000119 2.96 18765 6639 0.11

111.5 20000 37.90 71.77 71.95 0.000165 3.49 7810 1733 0.13

110.7 20000 43.10 71.12 71.30 0.000151 3.47 7991 3006 0.13

109.5 20000 41.10 70.43 70.54 0.000097 2.76 10359 3034 0.10

109.2 20000 40.10 70.22 70.32 0.000192 2.62 10617 2871 0.11

109.1 20000 37.00 70.17 70.23 0.000099 2.40 16938 3357 0.09

108.5 20000 39.30 69.86 69.94 0.000115 2.59 18478 6296 0.10

107.6 20000 38.00 69.09 69.15 0.000149 2.23 21388 7941 0.09

106.4 20000 35.40 68.19 68.26 0.000181 2.45 18722 7953 0.10

105.3 20000 24.90 67.10 67.26 0.000165 3.39 8064 999 0.12

103.1 20000 36.50 65.86 65.92 0.000089 2.39 29499 9322 0.09

100.1 20000 36.80 64.40 64.52 0.000108 3.11 17552 7629 0.12

99.51 20000 36.00 64.05 64.14 0.000130 2.82 15639 4327 0.11

99.4 20000 31.20 63.98 64.03 0.000090 1.93 17229 3940 0.07

97.5 20000 26.40 62.74 62.86 0.000201 2.97 10169 4290 0.11

96.82 20000 31.07 62.19 41.44 62.24 0.000155 2.11 19632 5959 0.09

96.805 Bridge

96.80 20000 31.07 62.09 62.14 0.000163 2.16 19013 5932 0.09

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

94.05 20000 28.00 61.58 61.66 0.000137 2.67 16869 4358 0.10

93.81 20000 28.30 61.34 61.44 0.000208 2.72 14210 4600 0.11

93.8 20000 33.81 61.26 61.40 0.000263 3.31 11300 4106 0.13

93.5 20000 27.10 60.94 61.05 0.000192 2.98 13742 4270 0.11

90.5 20000 27.40 58.60 58.70 0.000130 2.93 24623 7241 0.10

87.7 20000 20.90 57.55 57.58 0.000048 1.77 31198 7981 0.06

86.6 20000 22.90 57.23 57.25 0.000121 1.47 28086 7041 0.07

84 20000 21.50 55.68 55.77 0.000181 2.86 18968 7029 0.11

82 20000 15.40 54.41 54.44 0.000085 1.74 27376 8725 0.07

81.5 20000 22.80 54.23 54.28 0.000078 2.26 27050 8602 0.08

79.8 20000 21.30 53.42 53.46 0.000117 2.09 22079 6273 0.09

78.5 20000 15.90 52.63 52.67 0.000151 2.03 20964 6880 0.09

74.5 20000 17.10 50.84 50.88 0.000067 2.06 26323 6180 0.07

73.8 20000 15.00 50.33 50.50 0.000226 3.50 8651 1933 0.13

72.9 20000 14.50 49.67 49.71 0.000124 1.83 21624 5790 0.08

72.2 20000 11.10 49.08 49.21 0.000150 3.34 13038 3727 0.12

70.7 20000 16.00 48.13 48.21 0.000094 2.74 13534 1962 0.10

70.5 20000 12.70 47.97 48.09 0.000157 3.22 12062 2320 0.12

70.2 20000 15.80 47.81 47.89 0.000101 2.84 18317 4390 0.10

67.4 20000 16.20 45.32 45.46 0.000226 3.11 7790 6659 0.13

67.25 20000 13.50 45.07 45.30 0.000188 3.95 6485 6939 0.14

64.7 20000 12.00 43.51 43.62 0.000122 3.11 16450 5891 0.11

63.8 20000 8.20 43.17 43.22 0.000075 2.40 23764 4195 0.09

62.5 20000 10.60 42.59 42.76 0.000078 3.57 10956 3009 0.13

61.3 20000 3.40 42.01 42.09 0.000187 2.39 15814 4190 0.10

59.9 20000 9.50 40.91 41.09 0.000094 3.58 9243 2741 0.13

59 20000 4.50 40.52 40.65 0.000076 3.38 14760 3863 0.12

58.8 20000 7.00 40.48 40.56 0.000052 2.65 17709 3543 0.10

58.3 20000 6.00 40.19 40.36 0.000112 3.30 6369 406 0.13

57.7 20000 3.10 39.96 40.09 0.000065 3.10 10272 1516 0.11

56.9 20000 7.90 39.64 39.75 0.000106 2.83 10849 1542 0.12

56.7 20000 6.20 39.33 39.48 0.000175 3.15 6353 431 0.14

56.1 20000 10.00 38.59 38.79 0.000336 3.53 5668 441 0.17

55.5 20000 1.30 37.58 37.90 0.000264 4.52 4429 244 0.19

55.25 20000 3.30 37.30 37.54 0.000143 4.08 5637 446 0.15

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

55.23 20000 0.20 37.32 15.07 37.50 0.000104 3.49 6340 430 0.13

55.215 Bridge

55.21 20000 0.20 37.26 37.44 0.000105 3.50 6314 426 0.13

55.2 20000 0.20 37.25 37.44 0.000105 3.50 6313 426 0.13

54.5 20000 -1.10 36.99 37.10 0.000074 3.21 9038 720 0.11

54.49 20000 5.30 36.89 18.98 37.09 0.000108 3.85 6616 486 0.14

54.475 Bridge

54.47 20000 5.30 36.85 37.05 0.000108 3.86 6595 486 0.14

54.46 20000 5.30 36.84 37.04 0.000109 3.86 6590 485 0.14

54.45 20000 1.00 36.83 17.18 37.04 0.000097 3.86 6169 366 0.14

54.435 Bridge

54.43 20000 1.00 36.77 36.98 0.000098 3.87 6148 366 0.14

54.42 20000 1.00 36.77 36.98 0.000098 3.88 6146 366 0.14

54.4 20000 0.00 36.75 36.95 0.000122 3.65 5955 394 0.14

54 20000 4.30 36.41 36.65 0.000106 4.19 6309 679 0.14

52.4 20000 -0.40 35.69 35.81 0.000092 3.11 11290 1520 0.12

51.6 20000 5.00 35.16 35.32 0.000140 3.42 10465 2573 0.14

51.42 20000 5.24 35.14 14.14 35.17 0.000037 1.70 20997 3930 0.07

51.405 Bridge

51.40 20000 5.24 35.13 35.16 0.000037 1.70 20955 3929 0.07

50.8 20000 2.30 34.94 34.99 0.000091 2.22 18756 4998 0.10

49.6 20000 -1.60 34.52 34.59 0.000068 2.38 19288 5458 0.10

48.4 20000 1.00 33.89 34.00 0.000112 2.91 13509 3663 0.12

47.9 20000 5.60 33.66 33.81 0.000112 3.23 10019 2309 0.13

47.8 20000 9.40 33.62 33.78 0.000171 3.37 9485 2300 0.15

47.7 20000 0.10 33.52 33.67 0.000127 3.22 9754 2295 0.13

47.4 20000 -3.30 33.19 33.28 0.000058 2.42 13036 3360 0.11

46.8 20000 -2.80 32.94 33.04 0.000127 2.73 11957 3327 0.12

46.4 20000 -0.80 32.44 32.60 0.000211 3.33 8412 2293 0.15

45 20000 -9.80 31.55 31.65 0.000092 2.53 8935 2464 0.11

44 20000 -3.70 30.87 31.07 0.000154 3.73 9885 5451 0.15

42.4 20000 -4.00 29.42 29.65 0.000183 3.92 5526 1066 0.16

40.3 20000 -5.90 27.53 27.64 0.000187 2.84 12411 8246 0.12

38.9 20000 -7.80 26.51 26.64 0.000097 3.07 7994 674 0.12

36.3 20000 -6.80 24.98 25.20 0.000113 3.87 5976 566 0.15

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

34 20000 -7.80 23.19 23.39 0.000209 3.58 5590 386 0.17

31.2 20000 -8.60 20.59 20.91 0.000144 4.65 4782 397 0.18

28 20000 -6.30 18.09 3.36 18.46 0.000150 4.90 4274 288 0.20

TABLE 2

HYDRAULIC MODEL RUN RESULTS FOR

MAIN AND NORTH FLOODWAYS

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

139.03 105000 100.00 119.21 108.22 119.91 0.000686 6.72 15627 852 0.28

139.015 Inline Weir

139 105000 100.00 118.69 119.44 0.000752 6.91 15186 850 0.29

138 105000 100.10 118.58 108.63 119.26 0.000801 6.63 15849 996 0.29

137 105000 99.90 118.33 118.94 0.000708 6.25 16791 1051 0.28

136 105000 100.00 118.02 118.52 0.000580 5.70 18415 1140 0.25 135 105000 100.30 117.39 117.92 0.000635 5.82 18036 1158 0.26

134 105000 99.70 116.81 117.30 0.000594 5.64 18630 1196 0.25

133 105000 99.40 116.25 116.70 0.000577 5.44 19308 1279 0.25

132 105000 98.30 113.83 114.25 0.000564 5.17 20327 1430 0.24

131 105000 98.00 113.37 113.83 0.000620 5.40 19432 1372 0.25

130 105000 92.50 113.02 104.32 113.29 0.000389 4.86 25595 1937 0.20

129 105000 91.00 112.78 102.73 112.89 0.000161 3.02 39682 2974 0.13

128 105000 90.00 112.41 112.60 0.000317 4.26 30861 2691 0.18 127 105000 91.40 111.97 103.10 112.17 0.000287 3.99 30005 2308 0.17

126 105000 86.80 111.44 99.95 111.57 0.000146 3.14 36800 2329 0.13

125 105000 85.50 111.00 96.37 111.10 0.000100 2.67 41761 2431 0.10

124 105000 89.50 110.43 110.70 0.000342 5.08 26045 1908 0.20

123.03 105000 85.80 109.85 110.26 0.000825 6.93 20824 2065 0.29

123.02 105000 85.80 109.84 103.66 110.26 0.000923 5.63 20374 2065 0.20

123.015 Bridge

123.01 105000 85.80 109.77 110.19 0.000945 5.69 20213 2061 0.21

123 105000 85.80 109.76 110.18 0.000846 7.00 20647 2061 0.30

122.03 105000 85.90 109.83 101.24 110.07 0.000323 5.00 27537 2046 0.19

122.02 105000 85.90 109.83 101.22 110.07 0.000323 5.00 27536 2046 0.19

122.015 Bridge

122.01 105000 85.90 109.77 110.00 0.000328 5.03 27403 2045 0.19

122 105000 85.90 109.77 101.24 110.00 0.000329 5.03 27400 2045 0.19

121 105000 84.50 109.09 109.35 0.000372 5.35 26227 2018 0.20

120.03 105000 81.80 108.01 108.27 0.000342 5.36 26442 1930 0.20

120.02 105000 81.80 108.01 99.53 108.27 0.000342 5.36 26441 1930 0.20

120.015 Bridge

120.01 105000 81.80 107.96 99.53 108.22 0.000346 5.38 26346 1930 0.20

120 105000 81.80 107.96 108.22 0.000347 5.38 26343 1930 0.20

MAIN AND NORTH FLOODWAYS

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

119 105000 82.40 107.05 97.21 107.26 0.000270 4.38 28854 1993 0.17

118.03 105000 83.90 106.98 97.53 107.20 0.000318 4.43 27694 2021 0.16

118.02 105000 83.90 106.97 97.53 107.20 0.000318 4.43 27684 2021 0.16

118.015 Bridge

118.01 105000 83.90 106.97 97.53 107.20 0.000318 4.44 27674 2021 0.16

118 105000 83.90 106.97 97.53 107.20 0.000318 4.44 27674 2021 0.16

117.03 105000 83.00 105.89 97.86 106.18 0.000480 5.23 24357 1990 0.19

117.02 105000 83.00 105.89 97.86 106.18 0.000481 5.24 24349 1990 0.19

117.015 Bridge

117.01 105000 83.00 105.85 97.86 106.15 0.000484 5.25 24285 1989 0.19

117 105000 83.00 105.85 97.86 106.15 0.000484 5.25 24285 1989 0.19

116.03 105000 69.90 104.10 104.60 0.000565 7.71 22102 2072 0.26

116.02 105000 69.90 104.10 97.82 104.60 0.000565 7.71 22101 2072 0.26

116.015 Bridge

116.01 105000 69.90 104.00 104.51 0.000580 7.79 21893 2068 0.27 116 105000 69.90 104.00 104.51 0.000580 7.79 21893 2068 0.27

115.03 105000 75.70 102.11 102.42 0.000554 5.79 24729 2377 0.24

115.02 105000 75.70 102.11 96.11 102.42 0.000554 5.79 24728 2377 0.24

115.015 Bridge

115.01 105000 75.70 102.08 102.39 0.000559 5.81 24655 2376 0.24

115 105000 75.70 102.08 102.38 0.000560 5.82 24647 2376 0.24

114 105000 66.70 101.16 101.57 0.000450 6.58 23957 2130 0.23

113.03 105000 68.40 100.23 100.48 0.000475 5.94 27716 2820 0.22

113.02 105000 68.40 100.23 93.54 100.48 0.000475 5.94 27711 2820 0.22

113.015 Bridge

113.01 105000 68.40 100.19 100.44 0.000480 5.97 27608 2816 0.22

113 105000 68.40 100.19 100.44 0.000480 5.97 27606 2816 0.22

112 105000 68.90 100.03 92.70 100.14 0.000176 3.54 41883 3779 0.14

111 105000 69.40 99.03 99.21 0.000332 5.00 32338 3182 0.19

110 105000 69.80 97.99 92.20 98.06 0.000132 3.23 48443 4339 0.12

109.03 105000 68.40 97.42 97.56 0.000249 4.57 37291 3673 0.17

109.02 105000 68.40 97.42 90.93 97.56 0.000249 4.57 37291 3673 0.17

109.015 Bridge

109.01 105000 68.40 97.40 90.90 97.54 0.000251 4.58 37221 3672 0.17

109 105000 68.40 97.40 90.90 97.54 0.000251 4.58 37217 3672 0.17

108.03 105000 66.40 96.75 88.33 96.81 0.000109 2.29 55093 5076 0.10

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

108.02 105000 66.40 96.75 88.38 96.81 0.000109 2.29 55092 5076 0.10

108.015 Bridge

108.01 105000 66.40 96.75 88.34 96.81 0.000109 2.29 55087 5076 0.10

108 105000 66.40 96.75 88.35 96.81 0.000109 2.29 55085 5076 0.10

107.03 105000 67.80 96.05 87.67 96.16 0.000185 3.77 40688 3574 0.14

107.02 105000 67.80 96.05 87.67 96.16 0.000185 3.77 40686 3574 0.14

107.015 Bridge

107.01 105000 67.80 96.05 87.67 96.15 0.000185 3.77 40680 3573 0.14 107 105000 67.80 96.05 87.67 96.15 0.000185 3.77 40679 3573 0.14

106 105000 64.00 95.57 95.73 0.000220 4.21 33211 2438 0.16

105 105000 63.70 94.60 94.75 0.000214 4.53 35351 2802 0.15

104 105000 64.00 93.55 85.22 93.72 0.000247 4.65 32327 2505 0.17

103 105000 60.30 92.74 92.83 0.000133 3.58 44795 3545 0.12

102.03 105000 59.00 92.07 92.19 0.000182 4.08 38981 3195 0.14

102.02 105000 59.00 92.07 83.45 92.19 0.000182 4.08 38971 3194 0.14

102.015 Bridge

102.01 105000 59.00 92.06 92.18 0.000183 4.09 38942 3194 0.14

102 105000 59.00 92.06 92.18 0.000183 4.09 38942 3194 0.14

101 105000 57.20 90.62 83.79 90.83 0.000322 5.89 30163 2601 0.19

100 105000 60.10 89.49 90.10 0.000894 9.46 17980 1559 0.32

99 105000 57.10 89.26 81.74 89.74 0.000571 6.71 20024 1469 0.26

98 105000 54.10 87.52 87.80 0.000432 5.59 25846 2198 0.21

97.03 105000 52.00 86.88 87.21 0.000541 6.69 24953 2476 0.24

97.02 105000 52.00 86.88 81.47 87.21 0.000541 6.69 24952 2476 0.24

97.015 Bridge

97.01 105000 52.00 86.83 87.16 0.000550 6.73 24829 2474 0.25

97 105000 52.00 86.82 87.16 0.000550 6.73 24824 2474 0.25

96 105000 52.30 86.29 86.49 0.000339 4.81 30978 2888 0.19

95 105000 51.00 84.24 84.53 0.000460 5.83 27065 2781 0.23

94 105000 49.80 83.45 83.62 0.000355 4.80 34127 3913 0.20 93 105000 49.30 81.94 82.27 0.000735 6.76 27352 4245 0.28

92 105000 48.00 80.93 75.23 81.02 0.000178 3.53 47666 5338 0.14

91 105000 50.20 80.30 72.24 80.39 0.000150 3.14 46477 4348 0.13

90 105000 50.60 79.62 79.76 0.000156 3.85 37278 2597 0.14

89.03 105000 47.50 79.32 69.30 79.42 0.000119 3.23 43663 3151 0.12

89.015 Bridge

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

89 105000 47.50 79.32 79.42 0.000119 3.23 43652 3151 0.12

88 105000 49.00 78.86 69.07 78.99 0.000170 3.56 40529 3706 0.14

87 105000 49.40 78.38 78.64 0.000299 4.70 28924 2522 0.19

86 105000 47.60 77.68 77.87 0.000182 4.19 35203 3194 0.15

85.03 105000 46.70 77.04 77.20 0.000140 4.29 34850 2522 0.15

85.02 105000 46.70 77.04 67.27 77.20 0.000140 4.29 34846 2522 0.15

85.015 Bridge

85.01 105000 46.70 77.04 77.20 0.000141 4.30 34835 2522 0.15 85 84000 46.70 77.08 77.18 0.000089 3.42 34939 2523 0.12

84 84000 51.40 77.06 65.53 77.17 0.000087 3.34 33410 2154 0.12

83 84000 49.60 76.78 76.96 0.000116 3.86 26807 1639 0.14

82 84000 45.10 76.69 55.89 76.74 0.000028 2.08 57430 3928 0.07

81 84000 46.80 76.52 76.63 0.000073 3.33 34988 2260 0.11

80 84000 47.50 76.15 63.30 76.36 0.000147 4.60 24047 1463 0.16

79 84000 48.00 75.93 66.92 76.06 0.000111 3.83 32028 2415 0.13 78 84000 60.60 75.83 67.20 75.96 0.000167 3.34 29180 2441 0.15

77.03 84000 46.80 75.75 67.21 75.85 0.000106 3.75 34485 2739 0.13

77.02 84000 46.80 75.75 67.23 75.85 0.000106 3.75 34485 2739 0.13

77.015 Bridge

77.01 84000 46.80 75.73 67.21 75.84 0.000106 3.75 34447 2739 0.13

77 84000 46.80 75.73 67.21 75.84 0.000106 3.75 34447 2739 0.13

76 84000 50.00 75.62 62.97 75.68 0.000055 2.60 42258 2676 0.09

75 84000 53.00 75.58 62.39 75.65 0.000061 2.42 40168 2543 0.10

74.03 84000 52.90 75.23 62.34 75.39 0.000139 3.82 25843 1565 0.15

74.015 Bridge

74 84000 52.90 74.94 75.11 0.000147 3.90 25389 1563 0.15

73.03 84000 53.40 74.91 61.35 75.07 0.000118 3.50 26518 1474 0.13

73.015 Bridge

73 84000 53.40 74.67 74.83 0.000123 3.55 26158 1471 0.14

72.03 84000 49.10 74.61 74.75 0.000106 3.64 28320 1606 0.13

72.02 84000 49.10 74.61 61.06 74.74 0.000106 3.64 28313 1606 0.13

72.015 Bridge

72.01 84000 49.10 74.58 74.72 0.000107 3.64 28275 1606 0.13

72 84000 49.10 74.58 74.72 0.000107 3.64 28275 1606 0.13

71 84000 49.20 74.37 61.51 74.42 0.000048 2.24 46980 3148 0.09

70 84000 48.50 74.23 60.44 74.31 0.000065 2.59 38073 2323 0.10

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

69 84000 48.10 74.14 74.18 0.000029 1.86 55703 3468 0.07

68 84000 51.30 74.05 74.12 0.000057 2.52 38711 2226 0.09

67 84000 50.00 73.87 74.02 0.000094 3.28 27938 1468 0.12

66 84000 48.70 73.43 58.84 73.59 0.000125 3.75 28735 2184 0.14

65 84000 46.70 72.75 73.20 0.000273 5.40 15568 724 0.21

64 84000 46.70 72.78 58.25 72.90 0.000093 3.29 33997 2583 0.12

63 84000 52.00 72.78 60.56 72.86 0.000090 2.88 36697 2748 0.12

62.03 84000 50.30 72.47 63.88 72.57 0.000137 3.30 32855 2825 0.14

62.02 84000 50.30 72.47 63.90 72.57 0.000137 3.30 32842 2825 0.14

62.015 Bridge

62.01 84000 50.30 72.46 63.88 72.56 0.000137 3.30 32827 2825 0.14

62 84000 50.30 72.46 63.85 72.56 0.000137 3.30 32826 2825 0.14

61 84000 50.00 71.99 60.47 72.18 0.000187 4.36 24006 1620 0.17

60 84000 48.80 71.17 71.33 0.000156 3.97 25653 1676 0.15

59.03 84000 47.50 69.97 62.32 70.23 0.000373 5.42 20717 1897 0.21

59.02 84000 47.50 69.97 62.35 70.23 0.000373 5.42 20716 1897 0.21

59.015 Bridge

59.01 84000 47.50 69.97 62.32 70.23 0.000373 5.42 20711 1896 0.21

59 84000 47.50 69.97 62.32 70.23 0.000373 5.43 20709 1896 0.21

58 84000 46.80 69.67 69.79 0.000150 3.41 31014 2659 0.15

57 84000 44.60 68.84 69.06 0.000272 4.50 22508 1853 0.19

56 84000 45.60 67.53 67.80 0.000364 4.86 20710 1872 0.22

55.03 84000 44.20 67.23 67.33 0.000130 2.97 33595 2856 0.11

55.02 84000 44.20 67.23 58.49 67.33 0.000130 2.96 33597 2856 0.11

55.015 Bridge

55.01 84000 44.20 67.23 67.33 0.000130 2.96 33594 2856 0.11

55 84000 44.20 67.23 67.33 0.000130 2.97 33589 2856 0.11

54 84000 43.90 66.67 66.90 0.000270 5.24 22138 1766 0.20

53.03 84000 41.60 65.15 65.35 0.000277 4.72 24205 2268 0.18

53.02 84000 41.60 65.15 58.22 65.35 0.000277 4.71 24205 2268 0.18

53.015 Bridge

53.01 84000 41.60 65.15 65.34 0.000277 4.71 24200 2268 0.18

53 84000 41.60 65.15 65.34 0.000277 4.72 24197 2268 0.18

52 84000 42.10 64.75 55.57 64.89 0.000161 3.91 28262 2187 0.15

51.03 84000 40.50 63.74 63.95 0.000350 5.12 24419 2813 0.22

51.02 84000 40.50 63.74 58.32 63.95 0.000350 5.12 24409 2813 0.22

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

51.015 Bridge

51.01 84000 40.50 63.71 63.92 0.000353 5.14 24329 2811 0.22

51 84000 40.50 63.71 63.92 0.000354 5.15 24320 2811 0.22

50.03 84000 39.60 62.78 57.42 63.20 0.000569 7.60 16940 1626 0.29

50 84000 39.60 62.77 57.42 63.19 0.000572 7.61 16917 1625 0.29

49 84000 38.80 61.84 55.86 61.97 0.000214 3.91 29791 3160 0.17

48.03 84000 36.10 61.41 61.48 0.000099 2.46 39955 3625 0.11

48.02 84000 36.10 61.41 53.00 61.48 0.000099 2.46 39958 3625 0.11

48.015 Bridge

48.01 84000 36.10 61.41 61.48 0.000099 2.46 39951 3625 0.11

48 84000 36.10 61.41 61.48 0.000099 2.46 39945 3625 0.11

47 84000 38.30 61.28 61.34 0.000087 2.38 42683 3870 0.11

46 84000 37.00 61.03 61.15 0.000193 3.57 29879 2932 0.16

45 84000 36.00 59.85 59.98 0.000188 3.79 29536 2781 0.16

44.03 84000 33.50 58.84 58.96 0.000170 3.67 31059 2940 0.15

44.02 84000 33.50 58.84 51.17 58.96 0.000170 3.67 31038 2939 0.15

44.015 Bridge

44.01 84000 33.50 58.82 58.94 0.000171 3.68 30995 2938 0.15

44 84000 33.50 58.82 58.94 0.000171 3.68 30995 2938 0.15

43 84000 34.60 57.48 50.56 58.03 0.000645 7.66 14362 1141 0.29

42 84000 37.90 57.01 50.73 57.75 0.000865 8.61 12415 998 0.36

41 84000 28.20 56.83 57.50 0.000609 8.62 13780 1044 0.31

40 84000 26.60 56.38 49.21 56.53 0.000201 4.01 27942 2609 0.17 39 84000 26.00 54.80 54.99 0.000281 4.89 25912 2814 0.20

38 84000 25.00 54.45 48.51 54.67 0.000288 5.76 24024 2339 0.20

37.03 84000 24.40 54.39 54.64 0.000336 6.00 22533 2249 0.22

37.02 84000 24.40 54.39 48.53 54.64 0.000336 6.00 22532 2249 0.22

37.015 Bridge

37.01 84000 24.40 54.36 54.61 0.000339 6.02 22453 2248 0.22

37 84000 24.40 54.35 54.61 0.000339 6.02 22451 2248 0.22 36 84000 26.10 53.98 54.28 0.000398 5.97 20235 1926 0.23

35 84000 25.90 53.61 46.44 53.77 0.000207 4.16 27347 2485 0.17

34 84000 25.90 52.94 53.18 0.000337 5.37 23059 2425 0.22

33 84000 24.50 51.92 52.12 0.000259 4.69 24594 2279 0.19

32 84000 25.30 50.12 50.28 0.000235 4.59 26673 2567 0.18

31.03 84000 21.50 49.97 44.53 50.19 0.000343 5.21 23644 2552 0.22

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

31.015 Bridge

31 84000 21.50 49.67 49.91 0.000380 5.43 22891 2552 0.23

30.03 84000 24.40 49.58 49.86 0.000456 6.76 21362 2480 0.26

30.02 84000 24.40 49.58 44.97 49.86 0.000457 6.77 21409 2499 0.26

30.015 Bridge

30.01 84000 24.40 49.47 49.76 0.000475 6.88 21135 2495 0.26

30 84000 24.40 49.47 49.76 0.000475 6.88 21086 2477 0.26

29.03 84000 25.00 49.15 49.56 0.000735 7.31 18410 2565 0.32

29.02 84000 25.00 49.15 45.84 49.56 0.000735 7.31 18408 2565 0.32

29.015 Bridge

29.01 84000 25.00 49.06 49.48 0.000764 7.43 18169 2560 0.32

29 84000 25.00 49.06 49.48 0.000764 7.43 18167 2560 0.32

28 84000 20.40 49.00 49.30 0.000385 6.46 22309 2570 0.24

27 84000 16.60 46.14 46.41 0.000394 6.01 22049 2481 0.24

26 84000 17.00 45.17 40.60 45.39 0.000330 5.85 24755 2862 0.22

25.03 84000 15.70 43.57 43.77 0.000371 5.73 24198 2817 0.21

25.02 84000 15.70 43.57 38.52 43.77 0.000371 5.73 24197 2817 0.21

25.015 Bridge

25.01 84000 15.70 43.54 43.74 0.000374 5.75 24130 2816 0.21

25 84000 15.70 43.54 43.74 0.000374 5.75 24130 2816 0.21

24 84000 15.20 42.47 37.26 42.66 0.000309 5.09 25118 2742 0.20

23 84000 12.00 40.54 34.08 40.70 0.000222 4.35 27252 2612 0.18

22 84000 13.70 39.15 39.34 0.000289 4.78 26380 3008 0.20

21.03 84000 14.00 39.04 39.27 0.000394 5.56 23619 2872 0.23

21.02 84000 14.00 39.04 34.23 39.27 0.000394 5.56 23618 2872 0.23

21.015 Bridge

21.01 84000 14.00 39.01 39.24 0.000399 5.59 23515 2869 0.23

21 84000 14.00 39.01 39.24 0.000399 5.59 23515 2869 0.23

20 84000 11.40 37.99 38.18 0.000295 5.05 25099 2635 0.20

19 84000 7.50 36.64 36.84 0.000281 5.58 25291 2654 0.20

18.03 84000 8.10 36.35 36.79 0.000719 7.63 18197 2469 0.31

18.02 84000 8.10 36.35 32.77 36.79 0.000720 7.63 18195 2469 0.31

18.015 Bridge

18.01 84000 8.10 36.25 36.70 0.000749 7.75 17943 2465 0.32

18 84000 8.10 36.25 36.70 0.000749 7.75 17943 2465 0.32

17 84000 10.00 35.01 35.14 0.000178 3.95 30174 2801 0.16

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

16 84000 8.90 34.08 28.38 34.23 0.000266 4.34 27495 3020 0.19

15 84000 9.50 32.93 33.10 0.000292 4.76 26648 3042 0.20

14 84000 8.00 31.51 26.30 31.70 0.000285 5.11 25096 2565 0.20

13 84000 5.50 30.17 30.35 0.000265 4.44 25446 2492 0.19

12 84000 7.30 28.79 28.92 0.000174 3.88 29570 2614 0.16

11.03 84000 7.40 28.68 28.89 0.000340 5.35 23400 2445 0.22

11.02 84000 7.40 28.67 22.61 28.89 0.000341 5.35 23382 2445 0.22

11.015 Bridge

11.01 84000 7.40 28.65 28.87 0.000343 5.37 23328 2444 0.22

11 84000 7.40 28.65 28.87 0.000343 5.37 23328 2444 0.22

10 84000 4.20 26.09 26.26 0.000252 4.58 25448 2365 0.18

9 84000 2.10 24.74 24.93 0.000329 5.29 24593 2682 0.21

8 84000 1.20 22.96 17.00 23.20 0.000376 5.35 21906 2192 0.22

7.03 84000 1.60 22.90 23.16 0.000437 5.40 20611 2098 0.22

7.02 84000 1.60 22.90 17.09 23.16 0.000437 5.40 20605 2098 0.22

7.015 Bridge

7.01 84000 1.60 22.89 23.16 0.000438 5.40 20593 2098 0.22

7 84000 1.60 22.89 23.15 0.000438 5.40 20590 2098 0.22

6 84000 1.90 22.40 16.87 22.78 0.000600 6.58 17170 1695 0.28

5.1 84000 1.00 22.11 22.29 0.000288 4.62 25053 2505 0.19

5 84000 1.70 20.90 21.07 0.000299 4.61 25071 2585 0.20

4 84000 0.80 20.68 20.90 0.000409 5.38 22792 2591 0.23

3 84000 0.00 20.63 15.20 20.82 0.000344 5.01 24333 2676 0.21 2 84000 3.60 19.66 12.01 19.74 0.000125 2.79 36861 3529 0.13

1 84000 1.10 19.03 12.23 19.09 0.000117 2.35 41613 4542 0.12

TABLE 3

HYDRAULIC MODEL RUN RESULTS FOR

ARROYO COLORADO

River Sta Q Total Min Ch El

W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl

Flow Area

Top Width

Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

139 21000 64.30 77.90 78.04 0.000837 3.02 6959 636 0.16

138 21000 64.60 77.36 77.53 0.001064 3.32 6319 598 0.18

137 21000 65.50 76.15 76.38 0.001708 3.85 5461 593 0.22

136 21000 64.00 74.41 74.67 0.002417 4.09 5140 661 0.26

135 21000 65.20 73.68…