The Effects of Fires on Runoff and Infiltration

THE EFFECTS OF FIRES ON RUNOFF AND INFILTRATION

IN THE NAPA RIVER WATERSHED

A Project

Presented to the faculty of the Department of Civil Engineering

California State University, Sacramento

Submitted in partial satisfaction of the requirements for the degree of

MASTER OF SCIENCE

Civil Engineering

Vivian Esmeralda Gaxiola

SPRING 2018

Vivian Esmeralda Gaxiola

THE EFFECTS OF FIRES ON RUNOFF AND INFILTRATION

IN THE NAPA RIVER WATERSHED

A Project

Vivian Esmeralda Gaxiola

Approved by:

______, Committee Chair Dr. Cristina Poindexter

______, Committee Chair Dr. Tyler Hatch

______Date

iii

Student: Vivian Esmeralda Gaxiola

I certify that this student has met the requirements for format contained in the University format manual, and that this project is suitable for shelving in the Library and credit is to be awarded for the project.

______, Department Chair ______Dr. Benjamin Fell Date

Department of Civil Engineering

Abstract

THE EFFECTS OF FIRES ON RUNOFF AND INFILTRATION

IN THE NAPA RIVER WATERSHED

Vivian Esmeralda Gaxiola

During October 2017, the North Bay Wildfires wreaked havoc and tragedy across northern

California. The North Bay Wildfires were a series of wildfires that burned over 100,000 acres and killed over 20 civilians within the Mendocino, Napa, Lake, Solano, and Sonoma counties of

Northern California. The North Bay Wildfires had a disastrous impact on the natural resources within each county they burned. For engineers, environmentalists, and water managers, determining the impact that a wildfire has on a watershed within a region is crucial as it can cause

a greater risk of erosion, mudslides, and flooding. Wildfires have the potential to impact the

evaporation, transpiration, infiltration, runoff, water quality, and water supply of a watershed. This

study focused on the impact that the North Bay Wildfires had on infiltration and runoff within the

Napa River Watershed of Napa County, California. A hydrologic model was prepared to simulate

infiltration and runoff within the watershed and their impact from the North Bay Wildfires using

United States Army Corps of Engineering (USACE) Hydrologic Engineering Center Hydrologic

Modeling System (HEC-HMS). HEC-HMS simulated three scenarios: no fires, post-fire with low

severity and post-fire high severity for a 1-year storm event in March 2018. Simulating the no fire

condition help demonstrate the impact of the low and high severity post-fires. The results indicate

that the North Bay Wildfires increased runoff by 3.4% and could have potentially increased runoff

by 12.8% if fires had been high severity. The results also indicate that the North Bay Wildfires

decreased infiltration by 2-8% and could have potentially decreased infiltration by 10-35% if fires were high severity. By considering and understanding the impacts that fires have within a watershed, engineers, environmentalists, and water managers can work together to manage and improve the water infrastructure to control the release of water, protect the water supply (i.e. stored in reservoirs and groundwater) and natural resources.

______, Committee Chair Dr. Cristina Poindexter

______Date

ACKNOWLEDGEMENTS

First, I want to thank God for the good health, strength and wellbeing throughout these years. My

family members: Joel, Blanca, Byanka, Joel Jr. and Bryan Gaxiola, for their love and moral support.

My partner, Andres Guillen, for his love and advice, and always being available for me. My faculty

advisor, Dr. Cristina Poindexter, for advising me with the Masters Project. My committee member,

Dr. Tyler Hatch, for providing feedback on the Masters Project. Lastly, to all professors who taught

me new material at Sac State. I wouldn’t have finished the Graduate Program without any of their

help.

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TABLE OF CONTENTS

Page

Acknowledgements ...... vii

List of Tables ...... x

List of Figures ...... xi

Chapter

1. INTRODUCTION ...... 1

2. BACKGROUND ...... 2

2.1 Napa River Watershed ...... 2

2.2 North Bay Wildfires ...... 4

2.3 Impact of Atlas Fire on Napa River Watershed ...... 6

2.4 Impact of Nuns Fire on Napa River Watershed ...... 7

2.5 Impact of Tubbs Fire on Napa River Watershed ...... 9

2.6 Period of Interest for Simulation: March 2018 ...... 10

2.7 Previous Studies ...... 11

3. DATA COLLECTION ...... 13

3.1 Subbasins ...... 13

3.2 Reservoirs ...... 14

3.3 Precipitation ...... 17

3.4 Streamflow ...... 20

3.5 Runoff Curve Number ...... 21

4. MODEL ...... 24

4.1 Scenario 2 (Post-Fire with Low Severity) ...... 25

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4.2 Scenario 1 (No Fire) ...... 29

4.3 Scenario 3 (Post-Fire with High Severity) ...... 29

5. ANALYSIS OF RESULTS ...... 30

6. CONCLUSION AND RECOMMENDATIONS ...... 33

Appendix A. Subbasins ...... 37

Appendix B. Subbasins Summary ...... 38

Appendix C. Precipitation Gage Data Table ...... 42

Appendix D. Precipitation Areal Distribution ...... 45

Appendix E. Land Use Cover ...... 46

Appendix F. Soil Hydrology ...... 47

Appendix G. Jurisdictional Dams for State of California ...... 49

Appendix H. Reservoir Data ...... 50

Appendix I. Results Table ...... 53

References ...... 62

LIST OF TABLES

Tables Page

1. Fires in Napa River Watershed……………….… ...... ……………………………. 5

2. Rector Reservoir Information……………….… ...... ……………………………. 16

3. Curve Numbers (Pre-Fire) ...... ………….…………………………………. 21

4. Curve Numbers Summary………….……… ...... …………………………. 23

5. Infiltration Rates Summary……………………….……… …………………………. 32

LIST OF FIGURES

Figures Page

1. Map of Watersheds in Napa County… .... ………….…………………………………. 3

2. October 2017 Fires in Napa River Watershed ……… .………………………………. 5

3. Atlas Fire Perimeter… ...... ………….…………………………………. 7

4. Nuns Fire Perimeter… ...... ………….…………………………………. 8

5. Tubbs Fire Perimeter… ...... ………….…………………………………. 10

6. Creeks, Rivers, and Major Reservoirs…………….…………………………………. 15

7. Precipitation and Streamflow Gages… .. ………….…………………………………. 18

8. Thiessen Polygon……………………………….……… .. …………………………. 20

9. HEC-HMS Background Map ……………….……… ...... …………………………. 25

10. Subbasin-1 Information ...... ………….…………………………………. 26

11. Subbasin-1 Loss Tab… ...... ………….…………………………………. 26

12. Subbasin-1 Transform Tab ...... ………….…………………………………. 27

13. Reservoir Information ...... …………………………. 27

14. Reach Information ...... ………….…………………………………. 27

15. Junction-1...... ………….…………………………………. 28

16. Junction-1 Calibration… ...... ………….…………………………………. 29

17. Junction-2 Calibration ...... ………….…………………………………. 29

18. Total Outflow from Watershed ...... …………………………. 30

19. Subbasin-1 Soil Infiltration ...... ………….…………………………………. 31

20. Subbasin-2 Soil Infiltration ...... ………….…………………………………. 31

21. Subbasin-3 Soil Infiltration… ...... ………….…………………………………. 32

CHAPTER 1

INTRODUCTION

During October 2017, the North Bay Wildfires wreaked havoc and tragedy across northern

California. The North Bay Wildfires were a series of wildfires that burned over 100,000 acres and

killed over 20 civilians within the Mendocino, Napa, Lake, Solano, and Sonoma counties of

Northern California. The North Bay Wildfires had a disastrous impact on the natural resources

within each county they burned. For engineers, environmentalists, and water managers,

determining the impact that a wildfire has on a watershed within a region is crucial as it can cause

a greater risk of erosion, mudslides, and flood. Wildfires have the potential to impact the

evaporation, transpiration, infiltration, runoff, water quality, and water supply of a watershed. This

study focused on the impact that the North Bay Wildfires had on infiltration and runoff within the

Napa River Watershed (watershed) of Napa County, California.

A hydrologic model was prepared to simulate runoff and infiltration within the Napa River

Watershed and impacts from the North Bay Wildfires. The hydrologic model was built using the

United States Army Corps of Engineers (USACE) Hydrologic Engineering Center Hydrologic

Modeling System (HEC-HMS). HEC-HMS is a commonly used model for rainfall-runoff by the

Federal Emergency Management Agency (USGS 2005) and has been used in post-fire case studies

(Cydzik 2009). HEC-HMS was used to perform an analysis of the watershed under three scenarios for the month of March 2018. The first scenario simulated a condition in which no fires occurred within the watershed. The second scenario simulated post-fire conditions with a low severity burn impact. The third scenario simulated post-fire conditions with a high severity burn impact. The three conditions were compared to determine the impact that the North Bay Wildfires had on the watershed.

CHAPTER 2

BACKGROUND

2.1 NAPA RIVER WATERSHED

Napa River Watershed (watershed) is approximately 430 square miles and made up of 101

subbasins as determined by the Watershed Information and Conservation Council (WICC) (see

Appendix A). The watershed is located in the northern region of San Francisco Bay Hydrologic

Region and in the western region of Napa County. The largest river within the watershed is the

Napa River. Napa River is located between the cities of Calistoga and Napa and is over 50 miles long. Hundreds of creeks drain into Napa River, while the Napa River drains into the San Pablo

Bay (SWRCB 2011).

The Napa River Watershed is one of three watersheds within Napa County (see Figure 1). The

Napa River Watershed covers the western region, Putah Creek Watershed covers the northeast region, and Suisun Creek Watershed covers the southeast region of the county. According to the

Watershed Information and Conservation Council (WICC), 95% of the population living in Napa

County are located within Napa River Watershed boundaries, that is 129,670 people based on the

2010 Census. Some of the major cities within the watershed include: American Canyon, Calistoga,

St. Helena, Napa, and Yountville.

Figure 1 – Map of Watersheds in Napa County

As of 2017 (prior to the North Bay Wildfires), the United States Geological Survey (USGS) listed the majority of land coverage within the watershed as: Grasslands/Herbaceous (22.6%), Evergreen

Forest (21.5%), Orchards/Vineyards (12.9%), and Mixed Forest (9.3%) (see Appendix E).

Grasslands/Herbaceous land coverage is mostly located within the southern region of the watershed near American Canyon and Napa city. Evergreen Forest land coverage is mostly located within the mountainous regions that border the northern half of the Napa Valley. Orchards/Vineyards land coverage is mostly located within Napa Valley. Mixed Forest land coverage was located all across

the watershed but large continuous coverage was identified in the southern regions of the

watershed. According to the WICC, most of the soil within the watershed is identified as loam,

which is composed of a mixture of clay, sand, and silt.

The climate that Napa County experiences has a major impact on the characteristics of the

watershed. WICC describes Napa County having a Mediterranean climate, where it experiences

warm to hot dry summers and cold moist winters. The watershed experiences an annual rainfall

average of 24 inches in the northern region and 37 inches in the southern region (WRCC 2012).

2.2 NORTH BAY WILDFIRES

California Department of Forestry and Fire Protection (Cal Fire) grouped the North Bay Wildfires into three major fire complexes defined by their proximities to Mendocino and Sonoma Lake:

• Southern Cal Fire Sonoma-Lake Unit (Southern LNU Complex); comprised of the Atlas

Fire

• Central Cal Fire Sonoma-Lake Unit (Central LNU Complex); comprised of the Nuns,

Tubbs, and Pocket Fires

• Mendocino Lake Complex; comprised of the Redwood and Sulphur Fires

Of the three major complexes, those with Atlas, Nuns, and Tubbs Fires impacted Napa County (see

Figure 2 and Table 1).

Figure 2 – October 2017 Fires in Napa River Watershed

Table 1 – Fires in Napa River Watershed FIRE AREA BURNED* (AC) % BURNED IN WATERSHED Atlas Fire 4,614.06 1.97% Nuns Fire 19,969.12 8.53% Tubbs Fire 28,038.84 12.0% TOTAL 52,622.02 22.5% *Calculations using ArcGIS

2.3 IMPACT OF ATLAS FIRE ON NAPA RIVER WATERSHED

The Atlas Fire began on October 8, 2017 off of Atlas Peak Road, south of Lake Berryessa in Napa

County (see Figure 3). It lasted over 19 days until it was declared as 100% contained on October

27, 2017. According to the Watershed Emergency Response Team Report for the Atlas Fire

(WERT-AF), the fire destroyed 481 structures and burned over 51,000 acres of land under government and private ownership. The vegetation within the affected area mostly consisted of hardwood woodland and shrubland. Sparse amounts of agricultural land, coniferous forest, and grassland were also identified vegetation types with the burned area. Soils within the eastern region of the burn area were described as fine grained with deep profiles and within the western region of the burn area were described as gravelly with shallow profiles. It is important to note that the western region was described as having significant amounts of soil defined as bare rock outcrop.

These areas were sparsely populated by vegetation. The WERT-AF found that lands that drain into the Napa River, Putah Creek, and Suisun Creek Watersheds were burned by the fire. Specifically, the fire burned more than 28,000 acres of the Napa River watershed.

Figure 3 – Atlas Fire Perimeter

2.4 IMPACT OF NUNS FIRE ON NAPA RIVER WATERSHED

The Nuns Fire began on October 8, 2017 northwest of the Mayacamas Mountains, just east of Santa

Rosa and west from Yountville (see Figure 4). It lasted over 23 days until it was declared as 100% contained on October 31, 2017. According to the Watershed Emergency Response Team Report for the Nuns Fire (WERT-NF), the fire destroyed 486 structures and burned over 50,000 acres of land under private ownership. The vegetation within the affected area mostly consisted of coastal oak woodland. Sparse amounts of vineyards and grassland were also identified vegetation types

8 with the burned area. Soils in areas above 30% slopes were generally shallow with most common soil types being Goulding and Forward Gravelly Loam. The WERT-NF found that lands that drains into the Napa River, Sonoma Creek and Carneros Creek watersheds (Sonoma County) were burned by the fire.

Figure 4 – Nuns Fire Perimeter

2.5 IMPACT OF TUBBS FIRE ON NAPA RIVER WATERSHED

The Tubbs Fire began on October 8, 2017 off of Highway 120 and Bennett Lane, Calistoga (see

Figure 5). The fire was 97% contained on October 28, 2017. According to the Watershed

Emergency Response Team Report for the Tubbs Fire (WERT-TF), the fire destroyed 317 structures and burned over 36,000 acres of land under private ownership. The vegetation within the affected area mostly consisted of oak woodland, chaparral, conifer/hardwood, conifer, and urban environments. Most of the riparian vegetation did not burn at high intensity and will recover rapidly compared to other burned areas. Soils within the central and northern region of the burn area were described as clayey to gravelly soils. Those soils located on slopes exceeding 40% are most likely to be susceptible to an increase of erosion. The WERT-TF found that the fire began in upper Napa

River Watershed then burned watersheds draining to Putah Creek and Russian River (Sonoma

County). WERT-TF determined that the Tubbs Fire burned 3.5% of the Napa River Watershed area and 0.1% of the Putah Creek Watershed area. Specifically, the fire burned more than 4,600 acres of the Napa River watershed.

Figure 5 – Tubbs Fire Perimeter

2.6 PERIOD OF INTEREST FOR SIMULATION: MARCH 2018

December 2017 and March 2018 were two time periods considered for analyzing the post-fire effects. The month with the largest rainfall, following the North Bay Wildfires, was selected to observe the greatest impact. December 2017 had a monthly rainfall of 0.08 inches while March had

5.5 inches in the entire watershed.

2.7 PREVIOUS STUDIES

Three studies were used to understand and assess the study of interest. The studies focused on

how post-fire effect the watersheds and runoff, post-fire runoff and erosion response, and methods used for estimating runoff using curve numbers.

2.7.1 Fire Effects on Watersheds

DeBano (2009) identified two ways in which fire effects watersheds. Processes of the hydrologic

cycle that are controlled by vegetation and the soil will be most affected by the fire, including

interception (from trees and plants), infiltration, evapotranspiration, soil moisture storage, and

overland flow of water (runoff). The destruction of vegetation and soil surface exposes the soil to

“raindrop impact” which increases runoff and can create erosion. The fire also forms a water-

repellent soil layer that reduces the water from infiltrating to the ground. This water-repellent layer

will cause an increase of runoff and streamflow since water is no longer leaving the system through

infiltration or evapotranspiration from the plants.

2.7.2 Post-Fire Runoff and Erosion Response

Vieira et al. (2015) performed a meta-analysis on soil burn severity and post-fire runoff and erosion response. In the study, soil burn is the heating-induced alterations to soil properties caused by fire.

The soil burn severity is used as an indicator for the direct impacts on the hydrological and erosion response from recent burnt areas. Mapping soil burn severities has become an operational process in the United States to assess risks from soil erosion. The findings of Vieira et al. show that the fire and its severity increased the runoff compared to unburnt conditions, but no significant differences were observed for fire events after 3 years or for different fire severities. The study indicates that fire effects can be significantly stronger between 0.5 to 1.5 years after the fire.

Based on these results, runoff in March 2018, just 5 months (0.4 years) after the North Bay

Wildfires of October 2017, would be expected to be significantly increased compared to unburnt

(no fire) conditions.

2.7.3 Pre-and Post-Fire Curve Number Methods

Foltz et al. (2009) identified the most commonly used Curve Number (CN) method for pre-fire runoff and researched methods for estimating post-fire runoff as part of their post-fire road treatment study. The Soil Conservation Service (SCS) was considered as the most used method for calculating pre-fire runoff by the Burned Area Emergency Response team. This method considers: rainfall, Hydrologic Soil Group, land use cover, hydrologic conditions, and topography. There are limited amount of studies on post-fire Curve Number, but this study identified 3 methods that were considered:

1. Livingston et al (2005) created a post-fire Curve Number table for various burn severities.

The table was created by using small watersheds of 0.12 to 2.5 square miles. The table

suggest using Curve Numbers between 80 to 83 for low severity, 89 for moderate severity,

and 95 for high severity.

2. Cerrelli (2005) performed an initial study on post-fire Curve Numbers, but no calibration

occurred. Therefore, this method was not recommended.

3. Higginson and Jarnecke (2007) used the following rules to determine post-fire Curve

Numbers:

• High severity CN = pre-fire CN + 15

• Moderate severity CN = pre-fire CN + 10

• Low severity CN = pre-fire CN + 5

CHAPTER 3

DATA COLLECTION

Data collection is a crucial component towards building any hydrologic model. The degree to which data accurately reflects a scenario it simulates has a profound impact on a model’s results and the validity of those results. The United States Army Corps of Engineers (USACE) Hydrologic

Engineering Center Hydrologic Modeling System (HEC-HMS) was used to build a hydrologic model that simulates infiltration and runoff within the Napa River Watershed (watershed). In order to build a model that simulates a watershed, HEC-HMS requires information on the watershed land use coverage, precipitation that the watershed receives, reservoirs within the watershed, and streamflow within the watershed. The following sections will elaborate on how the data was collected, processed and applied to the watershed model.

3.1 SUBBASINS

To define the model, subbasins need to be built to describe the area within the watershed. In HEC-

HMS, subbasins split a watershed into smaller components by area and describe the area within it with generalized characteristics (i.e. calculation methods, baseflows, curve number, land area, permeability, etc.). HEC-HMS performs a series of calculation within each subbasin to determine a series of outputs (i.e. loss due to infiltration, runoff as outflow, etc.). Each subbasin provides an average description of the land within it. The accuracy of a watershed’s description in HEC-HMS can increase with the amount of subbasins used to describe it.

The Watershed Information and Conservation Council (WICC) splits the watershed into 101 subbasins. The 101 subbasins were grouped into three larger subbasins in order to simplify the construction of the model, speed up its processing, and location of the streamflow gages. The three

14 subbasins were labeled as Subbasin-1, Subbasin-2 and Subbasin 3. Subbasin-1 represented the northern subbasins, Subbasin-2 represented the central subbasins, and Subbasin-3 represented the southern subbasins (see Appendix A).

3.2 RESERVOIRS

The Napa River Watershed houses over 20 reservoirs within its boundaries. Only four reservoirs were used to build the model: Bell Canyon Reservoir, Lake Hennessey, Milliken Reservoir and

Rector Reservoir (see Figure 6). The four major reservoirs supply water to the major cities in Napa

River Watershed. The remaining reservoirs were omitted from the model for two reasons:

1. The storage capacities for the omitted reservoirs were too small to have a meaningful

impact on the model (e.g. Kimball Reservoir has a storage capacity of 345 acre-feet).

2. Access to the data for the omitted reservoirs was very limited (i.e. incomplete or not found).

The state of California only collects data on reservoirs with a storage capacity of 10,000

acre-feet or greater.

Including the omitted reservoirs would improve the accuracy of the model. However, the construction of the model proceeded with only the four listed models because the improvement of accuracy gained from the including the omitted reservoirs would be minimal and the time required to collect that information would not be feasible relative to the time required to complete this study.

Figure 6 – Creeks, Rivers, and Major Reservoirs

3.2.1 Lake Hennessey

Built in the 1940’s, Lake Hennessey is currently the largest reservoir in the watershed and supplies water to the City of Napa. It has a storage capacity of 31,000 acre-feet (AF) and has an average annual inflow of 19,692 AF and a watershed area of 35,000 acres (County of Napa). The City of

Napa provided the December 2016 daily storage-outflow-elevation curve that was used in the

model (see data in Appendix H). The reservoir is part of the California Department of Water

Resources (DWR) jurisdictional dams. Reservoir characteristics are summarized in Appendix G.

3.2.2 Rector Reservoir

Rector Reservoir is the second largest reservoir and supplies water to Yountville. It is operated by

the California Department of Veterans Affairs (Cal Vet). It has a total a storage capacity of 4,400

AF. There’s no data available from Cal Vet, which led to the estimating of values for the storage-

outflow-elevation curve. It was assumed that the spillway is a broad-crested weir with spillway

discharge calculated by Equation 1.

= / (Eq. 1) 3 2 Where, Q is the spillway flowrate (cubic feet𝑄𝑄 per𝐶𝐶𝐶𝐶 𝐻𝐻second; cfs), C is the coefficient that has been

measured to be 2.66 for H/L values less than 0.5, L is the width of the spillway (ft.), and H is the

head of the weir (ft.). Table 2 provides information on the reservoir. See Appendix H for storage-

outflow-elevation curve table.

Table 2 – Rector Reservoir Information Reservoir Area at Normal Storage 82 acres Hydraulic Height 155 feet Normal Storage Elevation and Storage 372.5 feet and 4587 acre-feet Spillway Crest Elevation 372.5 Freeboard 3 feet

3.2.3 Bell Canyon Reservoir

Bell Canyon Reservoir supplies water to Saint Helena and is operated by the City of Saint Helena.

The reservoir has a storage capacity of 2,530 AF. Reservoir and dam information were collected online from the City of Saint Helena’s website. See Appendix H for storage-outflow-elevation curve table.

3.2.4 Milliken Reservoir

Milliken Reservoir is the smallest reservoir of the four major reservoirs. It has a storage capacity

of 1,390 AF. It has been supplying water to the City of Napa since early 1920’s and was its only source of supply until Lake Hennessey was formed. It has an average annual inflow of 2,350 AF and a watershed area of 6,000 acres (County of Napa). The City of Napa provided data on the storage-outflow curve for January 2018 and provided elevation-storage chart to help determine the elevation. See Appendix H for storage-outflow-elevation curve table.

3.3 PRECIPITATION

Precipitation data was retrieved from Napa County’s real-time rainfall and river-stream data network called “Napa Valley Regional Rainfall and Stream Monitoring System”. The system provided data for 17 precipitation gages within Napa River Watershed for the month of March

2018. Figure 7 shows the location for each precipitation gage: 5 gages are within Subbasin-1 (Gages

32, 34, 35, 41, and 43), 5 gages within Subbasin-2 (Gages 24, 26, 29, 31, and 42), and 7 gages within Subbasin-3 (Gages 13, 14, 15, 17, 22, 25, and 28).

Figure 7 – Precipitation and Streamflow Gages

March 2018 had a total of 5.6 inches recorded with the most rainfall occurring on March 22, 1.42

inches (26% of the month’s rainfall). This amount constitutes slightly less than a 1-year rainfall for this area (NOAA 2017). Appendix C shows a summary of rainfall collected by the 17 precipitation gages.

An arithmetic average of the gage data was calculated to find the areal distribution of precipitation

in the watershed. The Thiessen Polygon Method was used as the calculation method to determine

the areal rainfall. The polygons were constructed through the following steps:

1. Connecting precipitation gages (gray line)

2. Drawing perpendicular bisectors (black line)

3. Calculating Thiessen weights (using grid lines)

17 polygons were created to represent an area for each precipitation gage (see Figure 8). The area for each polygon was estimated and weighted for the three subbasins (see Appendix D). It is important to note that the Thiessen Polygon method is prone to producing a margin of error from the creation of its polygons. The polygons estimate the area of the land within their boundaries.

These areas don’t account for vertical changes (i.e. mountains) and other features that could impact the surface area with the polygons as well as the distribution of rainfall due to the orographic effect.

The accuracy of this method can be improved by including gages outside of the watershed that can represent the areal distribution of precipitation for the polygons on the outer edges of the watershed.

Figure 8 – Thiessen Polygon

3.4 STREAMFLOW

Streamflow data was retrieved from the DWR California Data Exchange Center (CDEC) and the

United States Geological Survey (USGS). The two systems provided data for two streamflow gages within Napa River Watershed for the month of March 2018. Figure 7 shows the location for each streamflow gages: one gage within Subbasin-2 (Gage 11456000) and one gage within Subbasin-3

(Gage 11458000).

The streamflow gages were used as the “observed flows” in the HEC-HMS model. Gage 11456000 represented the outflow (runoff) for Subbasin-1 and Gage 11458000 represented the outflow

(runoff) for Subbasin-2. The observed flows were used to calibrate the model between the actual

(observed) and the simulated flows.

3.5 RUNOFF CURVE NUMBER

The HEC-HMS model was set up to use the United States Department of Agriculture (USDA) Soil

Conservation Service (SCS) Curve Number (CN) method to calculate the loss as infiltration. The

SCS CN method requires a Curve Number for each subbasin which is determined by the land use cover and Hydrologic Soil Group (HSG) using the USDA Technical Release 55 (TR-55) (see Table

3).

Table 3 – Curve Numbers (Pre-Fire) CURVE NUMBERS FOR HSG COVER TYPE NATIONAL LAND COVER DATASET TYPES A B C D Water Open Water 100 100 100 100 Open Space (Good) Developed, Open Space 39 61 74 80 Residential - 1/2 acre Developed, Low Intensity 54 70 80 85 Residential - 1/8 acre Developed, Medium Intensity 77 85 90 92 Commercial & Business Developed, High Intensity 89 92 94 95 Fallow Bare Soil Barren Land 77 86 91 94 Aspen (Good) Deciduous Forest 30 30 41 48 Woods (Good) Evergreen Forest 30 55 70 77 Woods (Fair) Mixed Forest 36 60 73 79 Brush (Fair) Shrub/ Scrub 35 56 70 77 Pasture, Grassland (Fair) Grassland/Herbaceous 49 69 79 84 Meadow Pasture, Hay 30 58 71 78 Row Crops - SR (Good) Cultivated Crops 67 78 85 89 Wetlands Woody Wetlands 100 100 100 100 Wetlands Emergent Herbaceous Wetlands 100 100 100 100 Small Grain 65 76 84 88

The land use cover for Napa River Watershed (pre-fire) was obtained from USGS as an ArcGIS shapefile. The area for each land use cover was determined for the entire watershed and for 101 subbasins.

The HGS is divided into four groups: A, B, C, and D. USDA defines each group as:

• Group A: Soils having a high infiltration rate (low runoff potential) when thoroughly wet.

These consist mainly of deep, well drained to excessively drained sands or gravelly sands.

These soils have a high rate of water transmission.

• Group B: Soils having a moderate infiltration rate when thoroughly wet. These consist

chiefly of moderately deep or deep, moderately well drained or well drained soils that have

moderately fine texture to moderately coarse texture. These soils have a moderate rate of

water transmission.

• Group C: Soils having a slow infiltration rate when thoroughly wet. These consist chiefly

of soils having a layer that impedes the downward movement of water or soils of

moderately fine texture or fine texture. These soils have a slow rate of water transmission.

• Group D: Soils having a very slow infiltration rate (high runoff potential) when thoroughly

wet. These consist chiefly or clays that have a high shrink-swell potential, soils that have a

high-water table, soils that have a clay later at or near the surface. These soils have a slow

rate of water transmission.

The HSG information for each subbasin (101) was estimated from a map of soil hydrologic conditions derived from the Natural Resources Services’ Soil Survey Geographic Database provided by SoilsTeamRC through ArcGIS.

The HSG and the land use cover determined an estimated CN for each of the 101 subbasins. The

101 Curve Numbers were weighted averaged to get a Curve Number for each of the three subbasins in the model (Subbasin-1, Subbasin-2, and Subbasin-3). These Curve Numbers were assigned to

Scenario 1 since the land use cover data was only valid before fires occurred.

The Curve Numbers change for post-fires because of the burned land cover. Some studies but not all Vieira et al. (Year) indicate that the Curve Numbers increase as soil burn severity worsen (i.e. very low, low, moderate, and high). The method from Higginson and Jarnecke (2007) suggest adding 5 CNs for post-fire with low severity and 15 CNs to post-fire with high severity. The additional 5 and 15 CNs for post-fire low severity and high severity were applied to the 44 partially or completely burned subbasins of the 101 total subbasins. A weighted average was taken to calculate the final CNs used in the model for Scenarios 2 and 3. Table 4 summarizes the average curve numbers assigned to each subbasin (see Appendix B for detailed data).

Table 4 – Curve Numbers Summary Subbasin-1 Subbasin-2 Subbasin-3 Scenario 1: Pre-Fire (No Fire) 67 75 76 Scenario 2: Post-Fire (Low Severity) 68 76 79 Scenario 3: Post-Fire (High Severity) 71 80 86

CHAPTER 4

MODEL

A hydrologic model was chosen for the analysis to simulate the hydrologic process in the

watershed. The analysis focused on runoff and infiltration and the properties that would affect it directly. The hydrologic model was built using the United States Army Corps of Engineers

(USACE) Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) version

4.2.1. The model simulated the hydrologic process for three scenarios for March 2018. The first scenario simulated a condition in which no fires occurred within the watershed. The second scenario simulated post-fire conditions with a low severity burn impact. The third scenario simulated post-fire conditions with a high severity burn impact.

A background map was added to the basin model (shown in Figure 9) to visually display where each element (i.e. subbasins, reservoirs, river reach, and junctions) is located. The first simulation that was constructed was the second scenario. The second scenario was simulated first because it was considered to be closest to the existing condition. According to the WERT fire reports, the

North Bay Wildfires were identified as mainly low severity with few moderate and high severity areas. This scenario was then calibrated and this calibration was used as the basis for simulating the first and third scenario.

Figure 9 – HEC-HMS Background Map

4.1 SCENARIO 2 (POST-FIRE WITH LOW SEVERITY)

4.1.1 Set up

The construction of the first simulation (second scenario) took the longest because it required all of the information for each element to be entered and calibrated. The first step was to define the subbasins by area, downstream, junction, loss and transform methods. Figure 10 shows a screen shot of Subbasin-1 input values.

Figure 10 – Subbasin-1 Information

The second step was to define the initial abstraction, curve number, and permeability information

(see Figure 11). The initial abstraction (which is defined as the fraction of rainfall depth intercepted or stored in depression before runoff begins (Ponce 2015)) was set as 0.001 during the calibration process. The impervious value was set as 1%.

Figure 11 – Subbasin-1 Loss Tab

The transform method used a lag time of 30 minutes (see Figure 12). The lag time is used to delay the runoff (from a rainfall event) to the time it reaches the maximum peak (USDA 2010).

Figure 12 – Subbasin-1 Transform Tab

The next step was to enter the four major reservoirs’ information which included the downstream junction, storage-elevation-outflow table, and an initial elevation (see Figure 13).

Figure 13 – Reservoir Information

The next element was the river reach. Three reaches (Reach-1, Reach-2, and Reach-3) were added to represent the stream through each subbasin.

Figure 14 – Reach Information

After identifying the subbasins, reservoirs, and river reach, the last step is to add the junctions to

the model and link the elements to the junctions downstream (see Figure 15).

Figure 15 – Junction-1

4.1.2 Calibration

When running the model, there were several errors that were triggered for precipitation gages.

USACE released a note stating that values set as zero were interpreted as missing data by the model.

To fix the error, a setting had to be selected to replace missing data with default values. This change

avoided any negative precipitation that was being calculated. A few other errors occurred with

storage-elevation-outflow table because of the model’s calculated storage was lower than the

minimum storage provided on the table. The errors were fixed by assuming that that at a low storage

(0 acre-feet) there was no outflow (0 cfs).

After running the model, Junction-1 was calibrated by comparing its results with Gage 11456000

(observed flow) and Junction-2 was calibrated by comparing its results with Gage 11458000

(observed flow) (see Figures 16 and 17; the blue solid line represents the flows calculated by the

model and black solid line represents the observed flows from the gages). There’s a discrepancy

between Junction-2 and the gage, and that’s possibly from beaver activity downstream from the

gage that could have cause inconsistent flows.

Figure 16 – Junction-1 Calibration

Figure 17 – Junction-2 Calibration

4.2 SCENARIO 1 (NO FIRE)

The model remained the same as Scenario 2, but only the Curve Numbers changed to reflect the pre-fire/no fire condition. Results are provided in Chapter 5.

4.3 SCENARIO 3 (POST-FIRE WITH HIGH SEVERITY)

The model remained the same as Scenario 2, but only the Curve Numbers changed to reflect the post-fire with high severity burned condition. Results are provided in Chapter 5.

CHAPTER 5

ANALYSIS OF RESULTS

The HEC-HMS results indicate a similar runoff pattern and infiltration rates for each subbasin for the month of March 2018 for all three scenarios. There were three peaks where the outflow increased significantly. The three peaks occurred on March 13, 15, and 22; the same day that the watershed received the most rainfall.

The runoff increased by 3.4% for low severity and 12.8% for high severity (see Figure 18). It was expected that the runoff would increase as the Curve Number increases by the severity of the burns.

Total Outflow from Watershed

No Fires Post-Fire with Low Severity Post-Fire with High Severity

12000

10000

8000

6000

Flow (cfs) 4000

2000

0 1-Mar-18 6-Mar-18 11-Mar-18 16-Mar-18 21-Mar-18 26-Mar-18 31-Mar-18 Date

Figure 18 – Total Outflow from Watershed

The infiltration rate decreased throughout the watershed by 2-8% for Scenario 2 and 10-35% for

Scenario 3. See results for each subbasin in Figures 19-21 and Table 5.

Soil Infiltration Subbasin-1

No Fires Post-Fire with Low Severity Post-Fire with High Severity

0.7 0.6 0.5 0.4 0.3 Loss (in) 0.2 0.1 0 1-Mar-18 6-Mar-18 11-Mar-18 16-Mar-18 21-Mar-18 26-Mar-18 31-Mar-18 Date

Figure 19 – Subbasin-1 Soil Infiltration

Soil Infiltration Subbasin-2

No Fires Post-Fire with Low Severity Post-Fire with High Severity

0.6 0.5 0.4 0.3

Loss (in) 0.2 0.1 0 1-Mar-18 6-Mar-18 11-Mar-18 16-Mar-18 21-Mar-18 26-Mar-18 31-Mar-18 Date

Figure 20 – Subbasin-2 Soil Infiltration

Soil Infiltration Subbasin-3

No Fires Post-Fire with Low Severity Post-Fire with High Severity

0.6 0.5 0.4 0.3

Loss (in) 0.2 0.1 0 1-Mar-18 6-Mar-18 11-Mar-18 16-Mar-18 21-Mar-18 26-Mar-18 31-Mar-18 Date

Figure 21 – Subbasin-3 Soil Infiltration

Table 5 – Infiltration Rates Summary Infiltration Rate (inch/day) Scenario Subbasin-1 Subbasin-2 Subbasin-3 Scenario 1: No Fires 0.093 0.069 0.060 Scenario 2: Post-Fire with Low Severity 0.091 0.067 0.055 Scenario 3: Post-Fire with High Severity 0.084 0.057 0.039

The storm event used in this model was a 1-year storm event. If a larger storm event had been used

(i.e. 5-year, 10-year, etc.), a greater percentage increase in runoff would be expected. This is because the environmental conditions would remain the same (i.e. evaporation and ground coverage). When comparing a smaller storm (i.e. 1-year) with a larger storm (i.e. 5-year or higher) during the same time period, the ground coverage, permeability, and evaporation rates would be the same. Since the difference between evaporation rates and difference between infiltration rates are negligible, a similar amount of water would evaporate and infiltrate during both storm events leaving the varying difference as the surface runoff for each storm event. This would indicate that the larger storm event generates more runoff.

CHAPTER 6

CONCLUSION AND RECOMMENDATIONS

This study focused on the impacts that the North Bay Wildfires had on the infiltration and runoff

within the Napa River Watershed. The infiltration and runoff within the Napa River Watershed were simulated using the hydrologic model HEC-HMS with pre-and post-fire conditions. The hydrologic model was built and calibrated using land coverage, permeability, precipitation, reservoirs, and streamflow data from the Napa River Watershed for March 2018. The first condition simulated post-fire with a low-severity burn impact (scenario 2) using the calibration dataset. The second simulation assumed no fires (scenario 1) using pre-fire land coverage. The last condition simulated post-fire conditions with high-severity burn impact (scenario 3) using Curve Numbers associated to its high severity burn impact. Scenario 1 was used as the baseline condition to compare the impact of post-fire conditions simulated in scenarios 2 and 3. Upon comparison, the differences noted for infiltration and runoff between each of the three scenarios were substantial. In a subbasin level, infiltration decreased between 2% and 8% in scenario 2 and 10% and 25% in scenario 3. In the Napa River Watershed, runoff increased by 3.4% and 12.8% in scenario 2 and scenario 3, respectively. These impacts can have damaging effects within the watershed.

A decrease in infiltration will reduce the amount of recharge in groundwater and the amount of groundwater available for pumping. This becomes a critical issue for a watershed that depends on groundwater for water supply and for groundwater subbasins trying to reach sustainability by 2040 as described in the 2014 California Sustainable Groundwater Management Act.

An increase in runoff increases the amount of erosion and potential for flooding or mud sliding to

occur during a storm event. According to ABC News, a flood warning was announced on March

22, 2018 in Napa and Sonoma County for a 1-year storm event. This storm event occurred within

the same areas that had been burned by the North Bay Wildfires. No indications of erosion or mudslides were observed during this storm event and little to no damage from the storm event was recorded within the two counties. However, the region still faced risk from the increase in erosion and potential for mud sliding to occur. That risk would have been far greater had a larger storm event struck as opposed to the 1-year storm event or if greater burn severity had occurred. To mitigate risk of damage posed by the burn impact left from the North Bay Wildfires, the residents of the Napa River Watershed should do the following:

• Be informed of the potential after effects caused by wildfires (i.e. increase risk of flooding,

erosion, and mudslides)

• Develop and implement a safety plan for post fire flooding (i.e. communication, emergency

supplies, evacuations, road impacts, etc.)

• Stay aware and vigilant (i.e. news, radio) of upcoming storm events for 6-18 months

following the wildfire

• Use sandbags as barriers around property to reduce water damage from flooding

This study used modeling to consider and understand those impacts but modeling does have

limitations that one must consider. For this study, the data collection portion of building the Napa

River Watershed in HEC-HMS was limited to publicly available data and field studies not

performed as part of the study. Additionally, there was a lack of data for certain elements needed

to describe the watershed to a greater precision. The following elements are listed below:

• Few streamflow gages - Not having more streamflow gages made the calibration process

challenging. Junction-1 was compared with Gage 11456000 and Junction-2 was compared

with Gage 11458000. Gage 11458000 had beaver activity downstream of gage which

affected the data. This event led to having one gage with accurate data to calibrate, but the

results still showed a higher runoff than the observed flows from the gages.

• Few subbasins –Three subbasins were used to define the watershed within HEC-HMS as

opposed to the 101 subbasins provided by Watershed Information and Conservation

Council (WICC). These three subbasins were developed from the 101 subbasins. Each of

the three subbasins used aggregated values from each of the smaller subbasins within

them. As a result, the three subbasins with their aggregated characteristics are less precise

than using the 101 minor subbasins with their own characteristics.

• No post-fire land use cover data - Having land use cover data after the North Bay Wildfires

would have given a better estimation on the post-fire Curve Numbers. Also, having a

national land use cover for post-fire table, as there’s one from USDA on pre-fire, would

have been useful to identify the appropriate Curve Number for each land use cover.

• Assumptions made on permeability and initial abstraction - Knowing the permeability and

initial abstraction on the burning areas would give the modeler an idea of the assumptions

being made. The permeability and initial abstraction coefficients were used in the analysis

as a parameter to calibrate scenario 2 in the model. Using these parameters for each of the

scenarios would have increased accuracy in the results.

Rebuilding the model by considering the limitations above should provide a more accurate reflection on the impact that the North Bay Wildfires had on the infiltration and runoff within the

Napa River Watershed. Modeling is a powerful tool for simulating and understanding

36 watershed. By considering and understanding the impacts that fires have within a watershed, engineers, environmentalists, and water managers can work together to manage and improve the water infrastructure to control the release of water, protect water supply (i.e. stored in reservoirs and groundwater) and natural resources, and improve emergency response.

APPENDIX A

SUBBASINS

APPENDIX B

SUBBASINS CURVE NUMBER SUMMARY

AREA CURVE FID SUBBASIN NAME AREA HSG BURNED NUMBER (acres) (acres) PRE-FIRE NF LS HS SUBBASIN-1 0 Kimball Reservoir 2159 1997 B 59 64 74 1 Jericho Creek 1155 238 B 56 61 71 2 Garnett Creek - Main Fork 2663 5 B 58 63 73 3 Napa River - Upper Calistoga Reach 1507 283 C 75 80 90 4 Garnett Creek - East Fork 968 0 B 56 56 56 5 Bennett Creek 810 642 C 74 79 89 6 Simmons Canyon Creek 2097 0 C 71 71 71 7 Dutch Henry Creek 2571 0 D 77 77 77 8 Blossom Creek 1683 1091 C 71 76 86 9 Bell Canyon Reservoir 3526 0 B 56 56 56 10 Biter Creek 1189 0 C 70 70 70 12 Oat Hill Creek 1191 0 C 71 71 71 13 Napa River - Lower Calistoga Reach 1369 0 C 71 71 71 14 Maple Lane Area 1179 0 C 72 72 72 16 Cyrus Creek 1956 357 C 70 75 85 17 Rattlesnake Ridge Creek 813 0 D 77 77 77 18 Napa River - Larkmead Reach 1142 0 A 41 41 41 19 Kortum Canyon Creek 1852 0 B 56 56 56 20 Kellet Mine Creek 608 0 C 72 72 72 21 Napa River - Bale Mill Reach 1232 0 C 71 71 71 22 Canon Creek 1901 0 B 56 56 56 25 Bell Creek 772 0 C 70 70 70 26 Schramsberg Creek 495 0 C 72 72 72 27 Nash Creek 400 0 C 72 72 72 28 Ritchie Creek 1565 0 C 72 72 72 30 Mill Creek 1417 0 C 70 70 70 33 Hirsch Creek 850 0 B 56 56 56 35 Napa River - Upper St. Helena Reach 1985 0 C 76 76 76 36 Meadowood Creek 866 0 C 70 70 70 39 York Creek 2525 0 C 71 71 71 42 Sulphur Creek - Main Fork 3435 0 C 71 71 71 43 Sulphur Creek - North Fork 662 0 C 71 71 71 46 Heath Creek 1786 8 C 68 73 83 SUBBASIN-1 Curve Number Weighted Average 67 68 71

CURVE FID SUBBASIN NAME AREA BURNED HSG NUMBER (acres) (acres) PRE-FIRE NF LS HS SUBBASIN-2 11 Conn Creek - Upper Reach 2623 0 B 57 57 57 15 Moore Creek 4571 0 C 71 71 71 23 Chiles Creek - Main Fork 4126 0 C 73 73 73 24 Conn Creek - Main Fork 4436 0 C 71 71 71 29 Conn Creek - East Fork 1531 0 C 70 70 70 31 Chiles Creek - East Fork 1720 0 C 75 75 75 32 Elder Valley Creek 1845 0 B 64 64 64 34 Sage Creek 4247 0 D 82 82 82 37 Spring Valley Creek 898 0 C 70 70 70 38 Lake Hennessey 5165 0 C 76 76 76 40 Clear Creek 1485 0 C 70 70 70 Napa River - Lower St. Helena 41 3483 0 B 64 64 64 Reach 44 Conn Creek - Lower Reach 5219 17 C 76 81 91 45 Bale Slough 3853 0 D 77 77 77 47 Fir Canyon 1566 604 D 77 82 92 48 Vinehill Creek 2078 0 D 80 80 80 49 Rector Reservoir 6972 3335 D 77 82 92 50 Bear Creek 2290 1591 D 79 84 94 51 Napa River - Oakville Reach 1205 0 B 79 84 94 52 Bella Oak's Creek 1570 41 D 79 84 94 55 Doak Creek 1311 539 C 76 81 91 56 Caymus Creek 903 370 C 80 85 95 58 Yount Mill Creek 2230 0 D 79 79 79 59 Chase Creek 2839 1196 C 79 84 94 61 Napa River - Yountville Reach 2610 395 B 78 83 93 62 Hopper Creek 3003 0 C 77 77 77 SUBBASIN-2 Curve Number Weighted Average 75 76 80

AREA CURVE FID SUBBASIN NAME AREA HSG BURNED NUMBER (acres) (acres) PRE-FIRE NF LS HS SUBBASIN-3 53 Dry Creek 9603 5425 D 78 83 93 54 Milliken Reservoir 6141 5774 C 72 77 87 57 Campbell Flat Creek 826 437 B 55 60 70 60 Soda Creek 2966 2885 A 71 76 86 63 Montgomery Creek 1359 1110 C 70 75 85 64 Veteran's Creek 2676 0 C 77 77 77 65 Milliken Creek - West Fork 1200 1024 D 80 85 95 66 Wing Canyon 959 959 C 70 75 85 67 Hardman Creek 1715 841 B 65 70 80 68 Milliken Creek - Main Fork 4504 3217 D 79 84 94 69 Oak Knoll Creek 696 404 D 80 85 95 70 Redwood Creek 4509 2688 C 72 77 87 71 Napa River - Upper Napa City Reach 1778 0 B 78 78 78 72 Pickle Canyon 1807 1011 C 71 76 86 73 Sarco Creek 2825 1994 B 60 65 75 74 Salvador Channel 4614 0 C 78 78 78 75 Hagen Creek 2601 1125 B 62 67 77 76 Carneros Creek 5718 3148 C 75 80 90 77 Browns Valley Creek 1381 275 C 77 82 92 78 Napa River - Lower Napa City Reach 7321 19 C 76 81 91 79 Spencer/Murphy Creek 2427 1619 D 78 83 93 80 Tulucay Creek 2752 349 B 62 67 77 81 Huichica Creek 4070 2716 C 73 78 88 82 Congress Valley Creek 2129 2 C 78 83 93 83 Kreuse Creek 980 671 D 80 85 95 84 Cayetano Creek 2001 1202 D 82 87 97 85 Horseman's Creek 787 0 C 77 77 77 86 Buhman Creek 2438 0 C 78 78 78 87 Napa River Marshes - East 4738 0 D 86 86 86 88 Arroyo Creek 1306 299 C 77 82 92 89 Central Creek 430 43 D 84 89 99 90 South Creek 797 0 B 69 69 69 91 Suscol Creek 2075 490 D 83 88 98 92 Mud Slough 1573 0 C 74 74 74 93 Fagan Creek 4198 186 C 78 83 93 94 Sheehy Creek 2714 0 C 79 79 79 95 No Name Creek 1206 0 D 84 84 84 96 North Slough 2076 0 C 83 83 83 97 Rancho del Mar Creek 1951 0 D 86 86 86

AREA CURVE FID SUBBASIN NAME AREA HSG BURNED NUMBER (acres) (acres) PRE-FIRE NF LS HS 98 Newell Creek 905 0 C 79 79 79 99 American Canyon Creek 2450 0 C 79 79 79 100 Walsh Creek 882 0 C 79 79 79 SUBBASIN-3 Curve Number Weighted Average 76 79 86

APPENDIX C

PRECIPITATION GAGE DATA TABLE

Napa River Redwood Hopper GAGE City of Napa Milliken at Lincoln Creek at Mt Mt Veeder Creek at NAME Corp Yard Reservoir Ave Veeder Rd Hwy 29 STATION ID 13 14 17 19 22 24 SUBBASIN 3 3 3 3 3 2 3/1/18 0.2 0.2 0.2 0.28 0.28 0.2 3/2/18 0.04 0.08 0.08 0.2 0.16 0 3/3/18 0 0 0 0 0 0.12 3/4/18 0 0 0 0 0 0 3/5/18 0 0 0 0 0 0 3/6/18 0 0 0 0.08 0 0 3/7/18 0.2 0.16 0.2 0.2 0.24 0.12 3/8/18 0 0 0 0 0 0 3/9/18 0 0 0 0 0 0 3/10/18 0 0 0 0 0 0 3/11/18 0 0 0 0 0 0 3/12/18 0.16 0.2 0.24 0.36 0.16 0.24 3/13/18 0.64 0.68 0.64 0.96 0.72 0.48 3/14/18 0.24 0.2 0.16 0.16 0.12 0.12 3/15/18 0.4 0.4 0.84 0.76 0.52 0.44 3/16/18 0.16 0.08 0.12 0.16 0.24 0.08 3/17/18 0 0 0.08 0.12 0 0.24 3/18/18 0 0 0 0 0 0 3/19/18 0 0 0 0 0 0 3/20/18 0.28 0.32 0.36 0.56 0.28 0.48 3/21/18 0.6 0.6 1.12 1.28 0.48 1 3/22/18 0.76 0.68 1.4 1.64 0.84 1.44 3/23/18 0.08 0.08 0.04 0.08 0.08 0 3/24/18 0.04 0.04 0.04 0.04 0.04 0.04 3/25/18 0 0 0 0.04 0 0 3/26/18 0 0 0 0 0 0 3/27/18 0 0 0 0 0 0 3/28/18 0 0 0 0 0 0 3/29/18 0 0 0 0 0 0 3/30/18 0 0 0 0 0 0 3/31/18 0 0 0 0 0 0

CONTINUATION OF TABLE Sulphur Napa River at Conn Creek at GAGE Dry Creek ATLAS Lake Yountville Dam White NAME Fire Station PEAK Hennessey Cross Rd Spillway Sulphur Springs Rd STATION ID 25 26 28 29 31 32 SUBBASIN 1 2 2 2 2 1 3/1/18 0.56 0.12 0.28 0.32 0.36 0.72 3/2/18 0.16 0.08 0.16 0.12 0.12 0.16 3/3/18 0.04 0.04 0 0 0 0 3/4/18 0 0 0 0 0 0 3/5/18 0 0 0 0 0 0 3/6/18 0.04 0 0 0 0 0.04 3/7/18 0.08 0.12 0.32 0.08 0.08 0.12 3/8/18 0 0 0 0 0 0 3/9/18 0 0 0 0 0 0 3/10/18 0 0 0 0 0 0 3/11/18 0 0 0 0 0 0 3/12/18 0.2 0.2 0.2 0.24 0.24 0.12 3/13/18 1 0.48 1.04 0.56 0.6 0.76 3/14/18 0.16 0.12 0.12 0 0.04 0.16 3/15/18 1 0.56 1.08 0.44 0.44 1.12 3/16/18 0.12 0.08 0.12 0.16 0.08 0.28 3/17/18 0 0.04 0 0 0.04 0.04 3/18/18 0.04 0 0 0 0 0 3/19/18 0 0 0 0 0 0 3/20/18 0.64 0.52 0.28 0.52 0.48 0.64 3/21/18 1.16 1.04 1.12 0.88 0.88 1.04 3/22/18 1.76 1.48 1.44 1.12 1.16 2.08 3/23/18 0.04 0 0 0 0 0.08 3/24/18 0.04 0 0.04 0 0.04 0.08 3/25/18 0.04 0 0 0 0 0 3/26/18 0 0 0 0 0 0 3/27/18 0 0 0 0 0 0 3/28/18 0 0 0 0 0 0 3/29/18 0 0 0 0 0 0 3/30/18 0 0 0 0 0 0 3/31/18 0 0 0 0 0 0

CONTINUATION OF TABLE GAGE ST. HELENA Sulphur Creek Napa River at Petrified ANGWIN NAME 4WSW at Pope St Dunaweal Ln Forest STATION ID 34 35 41 42 43 SUBBASIN 1 1 1 2 1 3/1/18 0.6 0.68 0.56 0.56 0.6 3/2/18 0.12 0.12 0.12 0.28 0.2 3/3/18 0 0 0 0 0 3/4/18 0 0 0 0 0 3/5/18 0 0 0 0 0 3/6/18 0.08 0.04 0.08 0.04 0.16 3/7/18 0.2 0.12 0.12 0.16 0.16 3/8/18 0 0 0 0 0 3/9/18 0 0 0 0 0 3/10/18 0 0 0 0 0 3/11/18 0 0 0 0 0 3/12/18 0.16 0.12 0.16 0.28 0.28 3/13/18 1.12 0.6 0.96 1 1.12 3/14/18 0.16 0.16 0.2 0.12 0.4 3/15/18 1.16 0.68 0.72 0.84 0.76 3/16/18 0.28 0.16 0.16 0.28 0.12 3/17/18 0 0.04 0 0.08 0 3/18/18 0 0 0 0 0 3/19/18 0 0 0 0 0 3/20/18 0.72 0.64 0.56 0.84 0.52 3/21/18 1.04 0.84 0.76 1.08 0.68 3/22/18 2.56 1.64 2.16 2.44 1.76 3/23/18 0.12 0.04 0.08 0.04 0.16 3/24/18 0.08 0.04 0.12 0.12 0.12 3/25/18 0.04 0.08 0.04 0 0.08 3/26/18 0 0 0 0.04 0 3/27/18 0 0 0 0 0 3/28/18 0 0 0 0 0 3/29/18 0 0 0 0 0 3/30/18 0 0 0 0 0 3/31/18 0 0 0 0 0

APPENDIX D

PRECIPITATION AREAL DISTRIBUTION

Subbasin 1 Subbasin 2 Subbasin 3 Total Sta. Sub- Wghtd. Wghtd. Wghtd. Gage Name Area Area Area Area ID basin Avg. Avg. Avg. (mi2) City of Napa 13 62.5 3 - - - - 62.5 0.4 Corp Yard 14 Napa River at 26.6 3 - - - - 26.56 0.17 Lincoln Ave 0.6 2 - - 0.63 0.01 - - Redwood 17 Creek at Mt 23.4 3 - - - - 23.44 0.15 Veeder Rd 19 Mt Veeder 9.4 3 - - - - 9.38 0.06 Milliken 22 6.3 3 - - - - 6.25 0.04 Reservoir 24 Hopper Creek 9.4 2 - - 9.38 0.08 - - at Hwy 29 3.1 3 - - - - 3.13 0.02 25 Dry Creek 10.9 2 - - 10.94 0.1 - - Fire Station 8.6 3 - - - - 8.59 0.06 26 Napa River at 12.5 2 - - 12.5 0.11 - - Yountville Cross Rd 3.1 3 - - - - 3.13 0.02 28 ATLAS 23.4 2 - - 23.44 0.21 - - PEAK 12.5 3 - - - - 12.5 0.08 Lake 29 10.9 2 - - 10.94 0.1 - - Hennessey Conn Dam 31 12.5 2 - - 12.5 0.11 - - Spillway 32 Sulphur Creek 1.6 1 1.56 0.02 - - - - at White Sulphur 4.7 2 - - 4.69 0.04 - - Springs Rd 34 ST. HELENA 9.4 1 9.38 0.14 - - - - 4WSW 0.8 2 - - 0.78 0.01 - - 35 Sulphur Creek 6.3 1 6.25 0.09 - - - - at Pope St 3.1 2 - - 3.13 0.03 - - Napa River at 41 12.5 1 12.5 0.18 - - - - Dunaweal Ln 42 ANGWIN 12.5 1 12.5 0.18 - - - - 23.4 2 - - 23.44 0.21 - - Petrified 43 26.6 1 26.56 0.39 - - - - Forest TOTAL 336.6 68.75 1.00 112.34 1.00 155.47 1.00

APPENDIX E

LAND USE COVER

APPENDIX F

SOIL HYDROLOGY

Definitions from Natural Resources Conservation Services – Soil Survey Manual Ch. 3 EXCESSIVELY Water is removed very rapidly. The occurrence of internal free water DRAINED commonly is very rare or very deep. The soils are commonly coarse-textured and have very high hydraulic conductivity or are very shallow. SOMEWHAT Water is removed from the soil rapidly. Internal free water occurrence EXCESSIVELY commonly is very rare or very deep. The soils are commonly coarse-textured DRAINED and have high saturated hydraulic conductivity or are very shallow. WELL Water is removed from the soil readily but not rapidly. Internal free water DRAINED occurrence commonly is deep or very deep; annual duration is not specified. Water is available to plants throughout most of the growing season in humid regions. Wetness does not inhibit growth of roots for significant periods during most growing seasons. The soils are mainly free of the deep to redoximorphic features that are related to wetness. MODERATELY Water is removed from the soil somewhat slowly during some periods of the WELL year. Internal free water occurrence commonly is moderately deep and DRAINED transitory through permanent. The soils are wet for only a short time within the rooting depth during the growing season, but long enough that most mesophytic crops are affected. They commonly have a moderately low or lower saturated hydraulic conductivity in a layer within the upper 1 m, periodically receive high rainfall, or both. SOMEWHAT Water is removed slowly so that the soil is wet at a shallow depth for POORLY significant periods during the growing season. The occurrence of internal free DRAINED water commonly is shallow to moderately deep and transitory to permanent. Wetness markedly restricts the growth of mesophytic crops, unless artificial drainage is provided. The soils commonly have one or more of the following characteristics: low or very low saturated hydraulic conductivity, a high water table, additional water from seepage, or nearly continuous rainfall. POORLY Water is removed so slowly that the soil is wet at shallow depths periodically DRAINED during the growing season or remains wet for long periods. The occurrence of internal free water is shallow or very shallow and common or persistent. Free water is commonly at or near the surface long enough during the growing season so that most mesophytic crops cannot be grown, unless the soil is artificially drained. The soil, however, is not continuously wet directly below plow-depth. Free water at shallow depth is usually present. This water table is commonly the result of low or very low saturated hydraulic conductivity of nearly continuous rainfall, or of a combination of these. VERY POORLY Water is removed from the soil so slowly that free water remains at or very DRAINED near the ground surface during much of the growing season. The occurrence of internal free water is very shallow and persistent or permanent. Unless the soil is artificially drained, most mesophytic crops cannot be grown. The soils are commonly level or depressed and frequently ponded. If rainfall is high or nearly continuous, slope gradients may be greater.

APPENDIX G

JURISDICTIONAL DAMS FOR STATE OF CALIFORNIA

Dam Owner Dam Reservoir Certified Condition Dam Name County Number Name Height Capacity Status Assessment National Owner Crest Dam Downstream Reservoir Year Lat. Long. ID. No. type Length Type Hazard Restrictions Built

City of 16.003 Bell Canyon Saint 95 2,530 Certified Satisfactory Napa Helena

CA00149 38.56 -122.48 City 500 ERTH Significant No 1959

City of 7.003 Conn Creek 125 31,000 Certified Fair Napa Napa Extremely CA00104 38.48 -122.37 City 700 ERTH No 1946 High

City of 7.000 Milliken 110 1,980 Certified Satisfactory Napa Napa Extremely CA00102 38.38 -122.23 City 647 CORA No 1924 High

CA Dpt. 1.021 Rector Creek of Veteran 164 4,587 Certified Satisfactory Napa Affairs State Extremely CA00011 38.44 -122.35 890 ERTH No 1946 Agency High DATA PROVIDED BY: CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS

APPENDIX H

RESERVOIR DATA

Lake Hennessey Reservoir Operation – Dec. 2016 Report LAKE TOTAL SPILLWAY ACTUAL DATE CREEK INFLOW ELEV. INFLOW FLOW RELEASE (FEET) (CFS) (CFS) (CFS) (CFS) CONN CHILES SAGE 1 306.99 2.59 0.35 0.29 3.22 0 0.52 2 306.99 2.47 0.32 0.29 3.07 0 0.52 3 306.99 2.35 0.29 0.29 2.92 0 0.57 4 306.99 2.24 0.32 0.29 2.84 0 0.57 5 306.99 2.13 0.32 0.29 2.73 0 0.57 6 306.99 2.13 0.29 0.29 2.7 0 0.57 7 306.99 2.02 0.29 0.29 2.59 0 0.57 8 307.03 2.97 0.63 0.29 3.89 0 0.57 9 307.08 3.53 0.84 0.29 4.66 0 0.57 10 307.35 12.97 10.9 0.62 24.49 0 0.57 11 307.52 25.45 3.45 0.36 29.26 0 0.57 12 307.6 11.72 1.37 0.36 13.45 0 0.57 13 307.65 8.18 0.96 0.36 9.5 0 0.57 14 307.7 7.02 0.84 0.36 8.22 0 0.57 15 307.8 212.9 90.74 11.72 315.4 0 0.57 16 310.2 76.44 19.36 1.2 97 0 0.57 17 310.41 26.83 3.86 0.4 31.08 1.48 2.06 18 310.62 12.34 2.48 0.36 15.18 0 0.57 19 310.7 8.93 1.79 0.52 11.24 0 0.57 20 310.76 6.37 1.45 0.32 8.14 0 0.57 21 310.82 5.19 1.23 0.32 6.73 0 0.57 22 310.88 4.48 1.02 0.32 5.82 0 0.57 23 310.92 6.8 1.62 0.32 8.73 0 0.57 24 310.95 8.93 1.45 0.32 10.7 0 0.57 25 310.98 6.8 1.16 0.32 8.28 0 0.57 26 311.01 5.37 1.02 0.32 6.72 0 0.57 27 311.04 4.65 0.9 0.32 5.87 0 0.57 28 311.08 4.15 0.84 0.32 5.31 0 0.57 29 311.15 3.99 0.84 0.32 5.15 0 0.57 30 311.2 3.83 0.79 0.32 4.94 0 0.57 31 311.25 3.83 0.79 0.32 4.94 0 0.57 TOTAL 489.6 152.49 22.69 664.77 1.48 19.15 DATA PROVIDED BY: THE CITY OF NAPA PUBLIC WORKS – WATER DIVISION

Milliken Reservoir Operation – Jan. 2018 Report LAKE HEAD OF DIV. DAM AT DATE INLET OUTLET DAM SPILL VOL. LK OUTLET TO STREAM (AF) (CFS) (CFS) (AF) (FT) (FT) 1 907.6 0 0 0 0 0 2 907.5 0 0 0 0 0 3 907.5 1.78 75.01 0 0.56 2.5 4 916.8 5.21 75.01 0 0.86 2.5 5 922.3 0.14 60.89 0 0.2 2.3 6 923.4 0 48.51 0 0.01 2.1 7 910.8 1.09 37.77 0 0.46 1.9 8 923.8 22.3 20.92 0 1.54 1.5 9 923.2 7.59 14.63 0 1 1.3 10 920.6 23.4 14.63 0 1.57 1.3 11 918.2 12.0 14.63 0 1.2 1.3 12 915.4 2.30 14.63 0 0.62 1.3 13 912.3 0.24 11.97 0 0.25 1.2 14 908 0 16.67 0 0.02 1.37 15 904.8 0 17.60 0 0.01 1.4 16 900.7 0 28.60 0 0 1.7 17 896.6 0 24.58 0 0 1.6 18 892.5 2.69 28.60 0 0.66 1.7 19 905.1 0.31 32.99 0 0.28 1.8 20 912.6 0.06 32.99 0 0.14 1.8 21 914.1 0 32.99 0 0 1.8 22 916.5 0.44 28.60 0 0.32 1.7 23 919.6 0 32.99 0 0.01 1.8 24 923.5 0 20.92 0 0.01 1.5 25 917.1 0 14.63 0 0 1.3 26 912.2 0 5.36 0 0 0.87 27 910.5 0 3.82 0 0 0.76 28 909.4 0 2.12 0 0 0.6 29 908.6 0 1.34 0 0 0.5 30 908.1 0 1.21 0 0 0.48 31 908 0 0.77 0 0 0.4 TOTAL 79.6 715.35 0 DATA PROVIDED BY: THE CITY OF NAPA PUBLIC WORKS – WATER DIVISION

Bell Canyon Reservoir ELEVATION DISCHARGE STORAGE (FT) (CFS) (AF) 410.3 0.80 1,552.6 410.88 1.82 1,589.1 410.96 1.84 1,594.3 410.99 1.90 1,596.3 411.03 2.65 1,598.9 411.1 3.18 1,603.4 411.28 4.13 1,615.2 413.2 4.17 1,746.0 414.0 4.49 1,797.0 421.23 4.43 2,383.7 422.02 4.49 2,383.7 DATA PROVIDED BY: THE CITY OF SAINT HELENA

Rector Reservoir ELEVATION FLOW STORAGE (FT) (CFS) (AF) 226.5 - 0 372.5 0 4,587 373.5 537.02 4,669.7 374.5 1,668.83 4,752.4 375.5 3,239.38 4,835.1 376.5 5,186.05 4,917.8 377.5 7,470.71 5,000.4 378.5 10,066.69 5,083.1 379.5 12,953.83 5,165.8 380.5 16,116.16 5,248.5 381.5 19,540.55 5,331.2

APPENDIX I

RESULTS TABLE

SCENARIO 1: NO FIRES

Subbasin-1 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.18 0.17 0.01 12.7 0 12.7 3-Mar-18 0:00 0 0 0 3.6 0 3.6 4-Mar-18 0:00 0 0 0 0.7 0 0.7 5-Mar-18 0:00 0 0 0 0.1 0 0.1 6-Mar-18 0:00 0.1 0.09 0.01 15 0 15 7-Mar-18 0:00 0.15 0.13 0.02 37.8 0 37.8 8-Mar-18 0:00 0 0 0 10.2 0 10.2 9-Mar-18 0:00 0 0 0 2 0 2 10-Mar-18 0:00 0 0 0 0.4 0 0.4 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.18 0.04 69.4 0 69.4 13-Mar-18 0:00 1.02 0.66 0.35 574.7 0 574.7 14-Mar-18 0:00 0.25 0.13 0.12 346.1 0 346.1 15-Mar-18 0:00 0.82 0.38 0.45 786.2 0 786.2 16-Mar-18 0:00 0.19 0.07 0.11 388.2 0 388.2 17-Mar-18 0:00 0.02 0.01 0.01 107.8 0 107.8 18-Mar-18 0:00 0 0 0 22.4 0 22.4 19-Mar-18 0:00 0 0 0 2.9 0 2.9 20-Mar-18 0:00 0.63 0.22 0.4 631.2 0 631.2 21-Mar-18 0:00 0.84 0.25 0.59 1095.7 0 1095.7 22-Mar-18 0:00 2.06 0.46 1.6 2801.4 0 2801.4 23-Mar-18 0:00 0.11 0.02 0.09 896.2 0 896.2 24-Mar-18 0:00 0.11 0.02 0.09 323.4 0 323.4 25-Mar-18 0:00 0.05 0.01 0.04 139.7 0 139.7 26-Mar-18 0:00 0.01 0 0.01 36.9 0 36.9 27-Mar-18 0:00 0 0 0 7.8 0 7.8 28-Mar-18 0:00 0 0 0 1.2 0 1.2 29-Mar-18 0:00 0 0 0 0.1 0 0.1 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-2 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.15 0.14 0.01 18.6 0 18.6 3-Mar-18 0:00 0.02 0.02 0 9.3 0 9.3 4-Mar-18 0:00 0 0 0 2.2 0 2.2 5-Mar-18 0:00 0 0 0 0.4 0 0.4 6-Mar-18 0:00 0.02 0.01 0 4 0 4 7-Mar-18 0:00 0.16 0.13 0.02 56 0 56 8-Mar-18 0:00 0 0 0 15.6 0 15.6 9-Mar-18 0:00 0 0 0 3.1 0 3.1 10-Mar-18 0:00 0 0 0 0.6 0 0.6 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.17 0.05 119.2 0 119.2 13-Mar-18 0:00 0.8 0.48 0.32 770.1 0 770.1 14-Mar-18 0:00 0.11 0.05 0.06 339.7 0 339.7 15-Mar-18 0:00 0.77 0.31 0.45 1116.4 0 1116.4 16-Mar-18 0:00 0.15 0.05 0.1 538.5 0 538.5 17-Mar-18 0:00 0.05 0.02 0.03 196.1 0 196.1 18-Mar-18 0:00 0 0 0 50.6 0 50.6 19-Mar-18 0:00 0 0 0 8.3 0 8.3 20-Mar-18 0:00 0.55 0.17 0.38 885.5 0 885.5 21-Mar-18 0:00 1.03 0.24 0.79 2059.4 0 2059.4 22-Mar-18 0:00 1.66 0.27 1.38 3738.2 0 3738.2 23-Mar-18 0:00 0.02 0 0.02 1037.5 0 1037.5 24-Mar-18 0:00 0.05 0.01 0.04 305.6 0 305.6 25-Mar-18 0:00 0.01 0 0.01 78.6 0 78.6 26-Mar-18 0:00 0.01 0 0.01 26.3 0 26.3 27-Mar-18 0:00 0 0 0 6.5 0 6.5 28-Mar-18 0:00 0 0 0 1.1 0 1.1 29-Mar-18 0:00 0 0 0 0.2 0 0.2 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-3 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.08 0.08 0 12.9 0 12.9 3-Mar-18 0:00 0.01 0.01 0 5 0 5 4-Mar-18 0:00 0 0 0 1.1 0 1.1 5-Mar-18 0:00 0 0 0 0.2 0 0.2 6-Mar-18 0:00 0.01 0.01 0 1.9 0 1.9 7-Mar-18 0:00 0.19 0.17 0.02 86.4 0 86.4 8-Mar-18 0:00 0 0 0 24.1 0 24.1 9-Mar-18 0:00 0 0 0 4.7 0 4.7 10-Mar-18 0:00 0 0 0 0.9 0 0.9 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.2 0.15 0.04 152.1 0 152.1 13-Mar-18 0:00 0.72 0.44 0.28 992.1 0 992.1 14-Mar-18 0:00 0.19 0.09 0.1 610.3 0 610.3 15-Mar-18 0:00 0.59 0.24 0.34 1323.1 0 1323.1 16-Mar-18 0:00 0.13 0.05 0.09 654.3 0 654.3 17-Mar-18 0:00 0.02 0.01 0.02 206.8 0 206.8 18-Mar-18 0:00 0 0 0 50.1 0 50.1 19-Mar-18 0:00 0 0 0 7.8 0 7.8 20-Mar-18 0:00 0.35 0.11 0.23 802.1 0 802.1 21-Mar-18 0:00 0.81 0.22 0.59 2252 0 2252 22-Mar-18 0:00 1.04 0.21 0.83 3466.1 0 3466.1 23-Mar-18 0:00 0.06 0.01 0.05 1095.8 0 1095.8 24-Mar-18 0:00 0.04 0.01 0.03 340.4 0 340.4 25-Mar-18 0:00 0 0 0 86.1 0 86.1 26-Mar-18 0:00 0 0 0 11.9 0 11.9 27-Mar-18 0:00 0 0 0 2 0 2 28-Mar-18 0:00 0 0 0 0.2 0 0.2 29-Mar-18 0:00 0 0 0 0 0 0 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

SCENARIO 2: POST-FIRE WITH LOW SEVERITY

Subbasin-1 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.18 0.17 0.01 13.1 0 13.1 3-Mar-18 0:00 0 0 0 3.7 0 3.7 4-Mar-18 0:00 0 0 0 0.7 0 0.7 5-Mar-18 0:00 0 0 0 0.1 0 0.1 6-Mar-18 0:00 0.1 0.09 0.01 15.6 0 15.6 7-Mar-18 0:00 0.15 0.13 0.02 39.3 0 39.3 8-Mar-18 0:00 0 0 0 10.6 0 10.6 9-Mar-18 0:00 0 0 0 2.1 0 2.1 10-Mar-18 0:00 0 0 0 0.4 0 0.4 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.18 0.05 72 0 72 13-Mar-18 0:00 1.02 0.65 0.36 593.2 0 593.2 14-Mar-18 0:00 0.25 0.13 0.12 356.4 0 356.4 15-Mar-18 0:00 0.82 0.36 0.46 805.9 0 805.9 16-Mar-18 0:00 0.19 0.07 0.11 397.4 0 397.4 17-Mar-18 0:00 0.02 0.01 0.01 110.3 0 110.3 18-Mar-18 0:00 0 0 0 22.9 0 22.9 19-Mar-18 0:00 0 0 0 3 0 3 20-Mar-18 0:00 0.63 0.22 0.41 643.9 0 643.9 21-Mar-18 0:00 0.84 0.24 0.6 1115.4 0 1115.4 22-Mar-18 0:00 2.06 0.44 1.62 2840.8 0 2840.8 23-Mar-18 0:00 0.11 0.02 0.09 908.3 0 908.3 24-Mar-18 0:00 0.11 0.02 0.09 327.4 0 327.4 25-Mar-18 0:00 0.05 0.01 0.04 141.3 0 141.3 26-Mar-18 0:00 0.01 0 0.01 37.3 0 37.3 27-Mar-18 0:00 0 0 0 7.8 0 7.8 28-Mar-18 0:00 0 0 0 1.3 0 1.3 29-Mar-18 0:00 0 0 0 0.1 0 0.1 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-2 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.15 0.14 0.01 19.4 0 19.4 3-Mar-18 0:00 0.02 0.02 0 9.7 0 9.7 4-Mar-18 0:00 0 0 0 2.3 0 2.3 5-Mar-18 0:00 0 0 0 0.4 0 0.4 6-Mar-18 0:00 0.02 0.01 0 4.2 0 4.2 7-Mar-18 0:00 0.16 0.13 0.02 58.5 0 58.5 8-Mar-18 0:00 0 0 0 16.3 0 16.3 9-Mar-18 0:00 0 0 0 3.2 0 3.2 10-Mar-18 0:00 0 0 0 0.6 0 0.6 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.17 0.05 124.4 0 124.4 13-Mar-18 0:00 0.8 0.47 0.33 797.8 0 797.8 14-Mar-18 0:00 0.11 0.05 0.06 351.2 0 351.2 15-Mar-18 0:00 0.77 0.3 0.46 1146.7 0 1146.7 16-Mar-18 0:00 0.15 0.05 0.1 552.2 0 552.2 17-Mar-18 0:00 0.05 0.01 0.03 200.8 0 200.8 18-Mar-18 0:00 0 0 0 51.8 0 51.8 19-Mar-18 0:00 0 0 0 8.4 0 8.4 20-Mar-18 0:00 0.55 0.16 0.39 903.8 0 903.8 21-Mar-18 0:00 1.03 0.23 0.8 2095 0 2095 22-Mar-18 0:00 1.66 0.26 1.4 3787.2 0 3787.2 23-Mar-18 0:00 0.02 0 0.02 1050.8 0 1050.8 24-Mar-18 0:00 0.05 0.01 0.04 309.3 0 309.3 25-Mar-18 0:00 0.01 0 0.01 79.5 0 79.5 26-Mar-18 0:00 0.01 0 0.01 26.6 0 26.6 27-Mar-18 0:00 0 0 0 6.6 0 6.6 28-Mar-18 0:00 0 0 0 1.1 0 1.1 29-Mar-18 0:00 0 0 0 0.2 0 0.2 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-3 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.08 0.08 0 11.4 0 11.4 3-Mar-18 0:00 0.01 0.01 0 4.6 0 4.6 4-Mar-18 0:00 0 0 0 1 0 1 5-Mar-18 0:00 0 0 0 0.2 0 0.2 6-Mar-18 0:00 0.01 0.01 0 1.9 0 1.9 7-Mar-18 0:00 0.19 0.17 0.03 92.8 0 92.8 8-Mar-18 0:00 0 0 0 25.9 0 25.9 9-Mar-18 0:00 0 0 0 5.1 0 5.1 10-Mar-18 0:00 0 0 0 1 0 1 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.2 0.15 0.05 168 0 168 13-Mar-18 0:00 0.72 0.41 0.3 1092.2 0 1092.2 14-Mar-18 0:00 0.19 0.09 0.11 667.8 0 667.8 15-Mar-18 0:00 0.59 0.22 0.37 1429 0 1429 16-Mar-18 0:00 0.13 0.04 0.09 703.5 0 703.5 17-Mar-18 0:00 0.02 0.01 0.02 221.7 0 221.7 18-Mar-18 0:00 0 0 0 53.7 0 53.7 19-Mar-18 0:00 0 0 0 8.4 0 8.4 20-Mar-18 0:00 0.35 0.1 0.25 853.8 0 853.8 21-Mar-18 0:00 0.81 0.18 0.62 2376.9 0 2376.9 22-Mar-18 0:00 1.04 0.17 0.87 3621.7 0 3621.7 23-Mar-18 0:00 0.06 0.01 0.05 1143.2 0 1143.2 24-Mar-18 0:00 0.04 0.01 0.03 354.3 0 354.3 25-Mar-18 0:00 0 0 0 89.5 0 89.5 26-Mar-18 0:00 0 0 0 12.4 0 12.4 27-Mar-18 0:00 0 0 0 2.1 0 2.1 28-Mar-18 0:00 0 0 0 0.2 0 0.2 29-Mar-18 0:00 0 0 0 0 0 0 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

SCENARIO 3: POST-FIRE WITH HIGH SEVERITY

Subbasin-1 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.18 0.17 0.01 14.6 0 14.6 3-Mar-18 0:00 0 0 0 4.1 0 4.1 4-Mar-18 0:00 0 0 0 0.8 0 0.8 5-Mar-18 0:00 0 0 0 0.2 0 0.2 6-Mar-18 0:00 0.1 0.09 0.01 17.6 0 17.6 7-Mar-18 0:00 0.15 0.13 0.02 44.2 0 44.2 8-Mar-18 0:00 0 0 0 12 0 12 9-Mar-18 0:00 0 0 0 2.4 0 2.4 10-Mar-18 0:00 0 0 0 0.4 0 0.4 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.17 0.05 80.6 0 80.6 13-Mar-18 0:00 1.02 0.61 0.4 652.9 0 652.9 14-Mar-18 0:00 0.25 0.12 0.13 389.2 0 389.2 15-Mar-18 0:00 0.82 0.33 0.49 867.2 0 867.2 16-Mar-18 0:00 0.19 0.06 0.12 425.7 0 425.7 17-Mar-18 0:00 0.02 0.01 0.01 117.9 0 117.9 18-Mar-18 0:00 0 0 0 24.5 0 24.5 19-Mar-18 0:00 0 0 0 3.2 0 3.2 20-Mar-18 0:00 0.63 0.19 0.43 682.5 0 682.5 21-Mar-18 0:00 0.84 0.21 0.63 1174.3 0 1174.3 22-Mar-18 0:00 2.06 0.38 1.68 2956.6 0 2956.6 23-Mar-18 0:00 0.11 0.02 0.09 944 0 944 24-Mar-18 0:00 0.11 0.02 0.09 339.2 0 339.2 25-Mar-18 0:00 0.05 0.01 0.04 146 0 146 26-Mar-18 0:00 0.01 0 0.01 38.5 0 38.5 27-Mar-18 0:00 0 0 0 8.1 0 8.1 28-Mar-18 0:00 0 0 0 1.3 0 1.3 29-Mar-18 0:00 0 0 0 0.1 0 0.1 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-2 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.15 0.14 0.01 23.4 0 23.4 3-Mar-18 0:00 0.02 0.02 0 11.7 0 11.7 4-Mar-18 0:00 0 0 0 2.7 0 2.7 5-Mar-18 0:00 0 0 0 0.5 0 0.5 6-Mar-18 0:00 0.02 0.01 0 5.1 0 5.1 7-Mar-18 0:00 0.16 0.13 0.03 70.9 0 70.9 8-Mar-18 0:00 0 0 0 19.7 0 19.7 9-Mar-18 0:00 0 0 0 3.9 0 3.9 10-Mar-18 0:00 0 0 0 0.8 0 0.8 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.22 0.16 0.06 148.7 0 148.7 13-Mar-18 0:00 0.8 0.42 0.38 922.5 0 922.5 14-Mar-18 0:00 0.11 0.04 0.06 402.5 0 402.5 15-Mar-18 0:00 0.77 0.25 0.51 1275.2 0 1275.2 16-Mar-18 0:00 0.15 0.04 0.11 609.4 0 609.4 17-Mar-18 0:00 0.05 0.01 0.04 220.3 0 220.3 18-Mar-18 0:00 0 0 0 56.8 0 56.8 19-Mar-18 0:00 0 0 0 9.2 0 9.2 20-Mar-18 0:00 0.55 0.13 0.42 978.1 0 978.1 21-Mar-18 0:00 1.03 0.18 0.85 2236.3 0 2236.3 22-Mar-18 0:00 1.66 0.19 1.46 3976.1 0 3976.1 23-Mar-18 0:00 0.02 0 0.02 1102 0 1102 24-Mar-18 0:00 0.05 0 0.05 323.2 0 323.2 25-Mar-18 0:00 0.01 0 0.01 82.8 0 82.8 26-Mar-18 0:00 0.01 0 0.01 27.6 0 27.6 27-Mar-18 0:00 0 0 0 6.8 0 6.8 28-Mar-18 0:00 0 0 0 1.1 0 1.1 29-Mar-18 0:00 0 0 0 0.2 0 0.2 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

Subbasin-3 Date Time Precip. Loss Excess Direct Flow Baseflow Total Flow (in) (in) (in) (cfs) (cfs) (cfs) 1-Mar-18 0:00 - - - 0 0 0 2-Mar-18 0:00 0.08 0.08 0 16.6 0 16.6 3-Mar-18 0:00 0.01 0.01 0 6.7 0 6.7 4-Mar-18 0:00 0 0 0 1.5 0 1.5 5-Mar-18 0:00 0 0 0 0.3 0 0.3 6-Mar-18 0:00 0.01 0.01 0 2.8 0 2.8 7-Mar-18 0:00 0.19 0.15 0.04 138.3 0 138.3 8-Mar-18 0:00 0 0 0 38.7 0 38.7 9-Mar-18 0:00 0 0 0 7.6 0 7.6 10-Mar-18 0:00 0 0 0 1.5 0 1.5 11-Mar-18 0:00 0 0 0 0 0 0 12-Mar-18 0:00 0.2 0.13 0.07 241.6 0 241.6 13-Mar-18 0:00 0.72 0.31 0.4 1452.2 0 1452.2 14-Mar-18 0:00 0.19 0.06 0.13 859.7 0 859.7 15-Mar-18 0:00 0.59 0.14 0.45 1739.5 0 1739.5 16-Mar-18 0:00 0.13 0.03 0.11 842.9 0 842.9 17-Mar-18 0:00 0.02 0 0.02 263.3 0 263.3 18-Mar-18 0:00 0 0 0 63.6 0 63.6 19-Mar-18 0:00 0 0 0 9.8 0 9.8 20-Mar-18 0:00 0.35 0.06 0.29 989.5 0 989.5 21-Mar-18 0:00 0.81 0.1 0.7 2688.4 0 2688.4 22-Mar-18 0:00 1.04 0.09 0.95 3986.8 0 3986.8 23-Mar-18 0:00 0.06 0 0.06 1253 0 1253 24-Mar-18 0:00 0.04 0 0.04 386 0 386 25-Mar-18 0:00 0 0 0 97 0 97 26-Mar-18 0:00 0 0 0 13.3 0 13.3 27-Mar-18 0:00 0 0 0 2.2 0 2.2 28-Mar-18 0:00 0 0 0 0.2 0 0.2 29-Mar-18 0:00 0 0 0 0 0 0 30-Mar-18 0:00 0 0 0 0 0 0 31-Mar-18 0:00 0 0 0 0 0 0

REFERENCES

ABC News. 2018. Storm Triggers Flooded Roadways, Warning in North Bay. http://abc7news.com/weather/storm-triggers-flooded-roadways-warnings-in-north- bay/3246157/.

ArcGIS. 2017. Soil Hydrology of the United States (beta). http://www.arcgis.com/home/webmap/viewer.html?webmap=d1c04fef017f4cfc95e69f71 84625744.

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