Coastal Change Rates and 

Patterns: Kaloko-Honokohau 

National Historical Park, Hawai’i 

U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

Open-File Report 2005-1069 

Coastal Change Rates and Patterns: 

Kaloko-Honokohau NHP, Kona 

Coast, Hawai’i 

By Cheryl J. Hapke,1 Rick Gmirkin,2 and Bruce M. Richmond1

Open-File Report 2005-1069 

2005

Any use of trade, firm, or product names is for descriptive purposes only and does not 

imply endorsement by the U.S. Government. 

U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY 

1

 U.S. Geological Survey, Pacific Science Center, 400 Natural Bridges Drive, Santa 

Cruz, CA 95060. 

2

 Kaloko-Honokohau National Historic Park, 73-4786 Kanalani Street, Suite #14, KailuaKona, HI 96740. 
LIST OF FIGURES 

FIGURE 1. Index map of Kaloko-Honokohau NHP showing specific locations discussed 

in text. 

FIGURE 2. Photographs showing the recreational, cultural and ecological resources at 

Kaloko-Honokohau NHP. 

FIGURE 3. Photographs showing the two different beach types in the park. 

FIGURE 4. Photomosaic of an intertidal beach forming a sand barrier spit across the 

mouth of Aimakapa Fishpond. 

FIGURE 5. Photographs showing evidence of sea-level rise and coastal erosion 

affecting resources in Kaloko-Honokohau NHP. 

FIGURE 6. Examples of the digitized shoreline erosion reference feature. 

FIGURES 7 -12. Change in beach area through time. 

FIGURE 13. Beach areas for all seven time periods. 

FIGURE 14. Along-shore erosion rates and variation in shoreline position. 

FIGURE 15. Variation in average shoreline change rates through time. 

FIGURE 16. Variation in beach area through time. 

FIGURE 17. Stability map of beaches in Kaloko-Honokohau NHP. 

ADDITIONAL DIGITAL INFORMATION

For additional information about Kaloko-Honokohau NHP, please see: 

http://www.nps.gov/kaho/

For additional information about NPS Geologic Resources Inventories, please see: 

http://www2.nature.nps.gov/geology/inventory/

For an online PDF version of this report, please see: 

http://pubs.usgs.gov.of/2005/2005-1069/

For more information on the U.S. Geological Survey Western Region’s Coastal and 

Marine Geology Team, please see: http://walrus.wr.usgs.gov/
INTRODUCTION

 A collaborative project between the U.S. Geological Survey’s Coastal and Marine 

Geology Program and the National Park Service (NPS) has been developed to create 

an inventory of geologic resources for National Park Service lands on the Big Island of 

Hawai'i. The NPS Geologic Resources Inventories are recognized as essential for the 

effective management, interpretation, and understanding of vital park resources. In 

general, there are three principal components of the inventories: geologic 

bibliographies, digital geologic maps, and geologic reports. The geologic reports are 

specific to each individual park and include information on the geologic features and 

processes that are important to the management of park resources, including 

ecological, cultural and recreational resources. This report summarizes a component of 

the geologic inventory concerned specifically with characterizing the coastal 

geomorphology of the beach system within Kaloko-Honokohau National Historical Park 

(NHP) and describes an analysis that utilizes georeferenced and orthorectified aerial 

photography to understand the spatial and temporal trends in shoreline change from 

1950 to 2002. In addition, spatial patterns of beach change were examined and a 

beach stability map was developed. Both the shoreline change rates and the beach 

stability map are designed to help Park personnel effectively manage the valuable park 

resources within the context of understanding natural changes to the KAHO beach 

system.

Study Area 

 Kaloko-Honokohau NHP (KAHO) is one of three national park lands along the 

Kona Coast of the Big Island of Hawai’i (Figure 1). KAHO was established in 1978 in 

order to preserve and protect traditional native Hawaiian culture and cultural sites. The 

park, a site of an ancient Hawaiian settlement, occupies 1160 acres and is considered a 

locale of considerable cultural and historical significance. Cultural resources include 

historic fishponds, petroglyphs and heiau (religious site). The fishponds are also

recognized as exceptional birding areas and are important wetlands for migratory birds. 

The ocean and reef have been designated as a Marine Area Reserve, and green sea 

turtles commonly come ashore to rest. The park is also a valuable recreational 

resource, with approximately 4-km of coastline and a protective cove ideal for 

snorkeling and swimming (Figure 2). 

 The park is underlain by three Holocene basalt flows (Wolfe and Morris, 1996) 

that originated from Hualalai Volcano. Both pahoehoe and a’a type flows are 

represented and age ranges for the flows are 1.5-3.0 ka (ka = thousand years), 3-5 ka, 

and 5-10 ka. They form a gently seaward-sloping surface upon which the park is 

situated. The geomorphology of the coast consists of a low-lying basalt platform or 

bench overlain by carbonate and basalt sand and gravel beaches. Two types of beach 

are present: intertidal accumulations of beach sediment subjected regularly to wave 

interaction, and perched beaches that are typically active (movement of sediment by 

waves) only during large-wave events (Figure 3). The perched beaches make up 

approximately 60% of the beach resource in the park. They consist of a thin veneer of 

sand and gravel deposited on the elevated basalt platform. The thickness is presently 

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unknown, but probably ranges between less than one to several meters. They are 

clearly lensoid in shape, pinching out both landward and seaward. Ultimately, the 

landward extent of the perched beach deposits is controlled by the elevation of the 

gradually sloping basalt flow and exposure to wave run-up. Locally, basalt flow 

topography influences where perched beaches are deposited. The intertidal beaches 

dominate in the southern portion of the park, where the basalt platform is lower in 

elevation. At Aimakapa Fishpond in the south-central portion of the park, the intertidal 

beach forms a barrier spit across the mouth of the fishpond (Figure 4). 

 There is clear evidence of sea-level rise and coastal erosion hazards within the 

park that threaten park resources (Figure 5). While there is no long-term water level 

data for the Kona Coast, tide gauge data from near Hilo (NOAA, 2004) indicates that 

average annual mean high water increased at a rate of 0.34 cm/yr between 1946 and 

2002.

METHODS

Aerial Photography

 Aerial photographs of the park were obtained for seven dates spanning six 

decades from 1950 to 2002 (Table 1). The photographs from 1950 through 1992 were 

scanned on a either a graphic arts or photogrammetric scanner at varying resolutions 

(see Table 1) and georeferenced in a GIS. The control points used for this process were 

derived from 2002 orthophotographs of the park as described below. The spatial errors 

associated with the georeferencing of the 1950-1992 photography are outlined in Table 

2 and are believed to be maximum estimates based examples of similar data 

processing (Hapke, 2004; in press). Unfortunately, a more accurate error assessment 

cannot be conducted as the specifics of the processing were not documented in detail.

The 2002 photography was orthorectified using surveyed ground control points and a 

digital terrain model using stereo photogrammetry. Therefore the errors inherent in 

these images are substantially less than the pre-2002, and are listed separately in Table 

2. The total error is estimated using a square root of the sum of the square method 

based on Hapke (2004; in press). The error analysis results in Table 2 are shown 

separately for the pre-2002 and the 2002 dates of photography because they were 

processed using different techniques. Relief displacement was not included in the error 

analysis because it is considered negligible due to the very low relief of the study area.

The total error is the estimate for the true positional error at any given location. 

However, this analysis focuses on the rates of shoreline change, and thus the summed 

error is divided by the 52-year time period of the analysis (1950-2002). The result, as 

shown in Table 2, demonstrates that the maximum error on the shoreline change and 

beach polygon change analyses is 0.12 m/yr. 

Shoreline Change and Beach Area Analysis 

 Georeferenced photographs were incorporated into a GIS for digitization of the 

shoreline reference feature as part of the change analysis. Due to the variable coastal 

geomorphology within the park, two different shoreline reference features were 

identified. For the intertidal beaches, the wet-dry line, identified by a difference in the 
TABLE 1. AERIAL PHOTOGRAPH SPECIFICATIONS 

Year Film* Nominal

Scale

Pixel Res.

(m)

Scanning Res.

(dpi)

Scanner

1950 B/W 1:30,000 0.5 600 graphic arts

Apr. 1954 B/W 1:25,000 0.9 600 graphic arts

Jan. 1965 B/W 1:31,000 1.0 300-600 graphic arts

Nov. 1970 B/W 1:15,000 0.7 300-600 graphic arts

June 1988 CIR 1:12,000 0.4 300-600 graphic arts

Feb. 1992 CIR 1:12,000 0.9 300-600 graphic arts

Oct. 2002 CIR 1:4,800 0.5 1200 photogrammetric

*B/W=black and white; CIR = color infrared 

TABLE 2. ERROR SOURCES 

 Year 

Error Source (m) 1950-92 2002

Scanner, media 2.0 --

Radial distortion 1.3 --

Pixel resolution 0.4 – 1.0 0.5

Ground control 2.0 0.5

Georef./rect. 5.0 2.0

Total error 6.3

Total rate error (m/yr) 0.12

tonal contrast between wet and dry sand, was used as the shoreline reference feature 

(Figures 3 and 6A). For the perched beaches, the contact between the light-colored

beach sediment and the underlying basalt platform was digitized as the shoreline 

reference feature (Figures 3B and 6B).

 Once the shoreline reference features were digitized, the Digital Shoreline 

Analysis System (DSAS; Thieler and others, 2003) was used to perform the change 

analysis. This technique requires first creating a shore-parallel line to be used as a 

baseline. Once the baseline is drawn, baseline-normal transects are generated at a 

designated spacing (in this analysis, 20 m). Both linear regression and end-point 

shoreline change rates were calculated where each transect crosses a shoreline 

reference feature. 

 In addition to quantifying the spatial distribution of shoreline change rates in the 

park, an analysis of the patterns of beach area change was undertaken. Both the 

seaward and landward beach margins were digitized from the seven dates of 

georeferenced aerial photographs. The seaward sides of the beach area polygons are 

coincident with the shoreline reference features described above and shown in figure 

6A and 6B. The landward side is the furthest inland extent that beach sediment can be 
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identified on the aerial photographs. The polygons and their significance will be 

discussed later in the text (see Beach Area Change Rates and Patterns, below). 

RESULTS AND DISCUSSION

Shoreline Change Rates

 The results of the linear regression shoreline change analysis from 1950 – 2002 

show that the dominant shoreline change signal in the park is erosional. The combined 

average of all the measurements taken yields an average erosion rate of -0.3 m/yr for 

the beaches in the park. Erosion rates vary along the coastline in the park and are 

shown graphically in Figure 7. There is a considerable alongshore variation in the rates, 

with several pronounced erosion hotspots, and one location where the long-term signal 

is accretional. The rates are lowest overall to the north of Kaloko Fishpond and along 

the barrier spit across the mouth of Aimakapa Fishpond (< 0.1 m/yr). The highest rates 

(>0.7 m/yr) were measured at Kaloko Point. The other hotspots occur north and south 

of Aimakapa Fishpond (0.6 m/yr) and at Honokohau Beach (0.6 m/yr) (Figure 7). 

 Average rates of shoreline change provide baseline information about the overall 

trends in the park. However, they provide little information as to the episodic nature of 

shoreline change processes. This analysis covers time periods ranging from four years 

(1988-1992) to eighteen years (1970-1988), and thus provides a snapshot of the state 

of the beaches for each year of photography; there is little information of what actually 

occurs on an annual basis. In order to gain additional understanding of the short-term 

signal within the average long-term change trend, end-point rates (average of all 

measurements) were calculated for each two adjacent time periods (i.e. 1950-1954, 

1954-1965, etc). This provides a record of how the rates themselves are changing 

through time. Figure 8 shows the results of the end-point analysis and suggests that the 

beach system in KAHO is in a state of dynamic equilibrium (Chorley and others, 1984; 

Richmond, 1992). In this situation, dynamic equilibrium is defined as variations about a 

characteristic form which itself has a trend through time. In KAHO, the beach system 

has a dominantly erosional trend, with average rates ranging from < 0.1 m/yr to ~0.5 

m/yr. The long-term erosion of ~ 0.3 m/yr is interrupted by periods of increased erosion 

or accretion that disrupt the system, after which it gradually returns to the equilibrium 

state. This is illustrated in (a) the doubling of the average erosion rate from the 1954-65 

to the1965-70 time period, and (b) the accretionary phase in the interval from 1988-92. 

Beach Area Change Rates and Patterns 

 The shoreline change analysis provides baseline data on the change through 

time of a linear feature (in this case the shoreline). This is a common technique of 

assessing erosion hazards and was developed primarily for measuring change on U.S. 

East and Gulf Coast beaches (Smith and Zarillo, 1990; Crowell and others, 1991). The 

beaches at KAHO, however, are small, discontinuous bodies of sediment that are 

dynamic and complex, and the shoreline change analysis alone cannot provide 

information on whether the beaches are becoming smaller through time (loss of area) or 

if the entire beach is shifting landward but not changing substantially in area. 

Knowledge of the loss rate or stability of the area of the beaches would be useful to the 

development of management plans for the park resources. 
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 As shown in Figures 9-14, polygons of the beach areas were digitized for each 

date of photography and the areas were calculated in a GIS. As shown in the 

superimposed polygons, the beaches change shape and size through time. There is a 

distinct increase in beach area in 1965 (Figure 10), which receded by 1970 (Figure 11).

Erosion continues but appears to be slowing from 1970 through 1992 (Figures 12 and 

13). In 2002, the beach area again shows a dramatic increase (Figure 14) similar to that 

which was measured in the 1965 photography. The graph in Figure 15 summarizes 

these beach area changes through time. Similar to the shoreline change analysis, it 

appears that there is an equilibrium state of the park beaches in which the beach area 

ranges from 45,000 to 50,000 m2

. This state is punctuated by periods (1965 and 2002) 

when the area of the beaches increases dramatically, followed by erosion over a 

relatively short time (decade or less) period during which it returns to an equilibrium 

state. If this pattern is typical, the beaches at KAHO should presently be undergoing 

accelerated erosion throughout the park, as the last phase of area increase occurred in 

2002. Increased beach recession has been observed by one of the authors (Rick 

Gmirkin), who has been qualitatively monitoring the park beaches for several years. If 

this trend continues, Park managers are likely to observe this increased erosional trend 

throughout the park until the beach areas reach extents similar to what they were in 

1992.

Beach Stability Analysis 

 The beach area change analysis provides an additional level of information 

beyond the shoreline change analysis that can be valuable for understanding coastal 

change within the park and for the effective management of park resources. In addition 

to quantifying the temporal patterns of change in beach area, this study also provides 

an analysis of the spatial variations of the beach through time and results in the 

development of a beach stability map. 

 The analysis of beach change clearly shows the dynamic nature of the beach 

system within KAHO. Figure 16 shows the superimposed polygons of beach area from 

Figures 9-14, which clearly shows the shifting nature of the beaches. It also indicates 

that some beach areas within the Park may be fairly stable. However, it is difficult to 

visualize the specific areas of stable versus unstable beach due to the dynamic nature 

of the changing beach areas. In order to address this problem we have summarized the 

changing beach areas within one map (Figure 17). This was accomplished by merging 

beach polygons into one map to encompass the areal extents of all the polygons from 

each time period. Next the polygons from each individual date of photography were 

gridded at a 1-m cell size, and each cell was assigned a value of one. The polygons 

were then summed within the bounds of the combined polygon. The resulting map 

(Figure 17) shows areas where a beach has existed for all of the seven dates of 

photography from which the polygons were digitized (value = 7), and where the beach 

has only existed for one or two dates (value = 1 or 2, respectively). We interpret this as 

a measure of relative beach stability which shows the spatial distribution of stable 

versus unstable beaches within the park for the period covered by the analysis (1950-


 

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2002). The blue and greens are the most stable beach areas and the reds and oranges 

are the least stable. 

 Some of the most stable beach areas coincide with the lowest erosion rates in 

the shoreline change analysis (see Figures 7 and 17), such as the barrier spit across 

Aimakapa Fishpond and the perched beach north of Kaloko Fishpond. However, this 

relationship is not consistent throughout the park. One noticeable location of this 

correlation between beach stability and shoreline erosion rate is poor is at Kaloko Point, 

which demonstrated the highest shoreline erosion rates but, based on the beach 

stability map, has one of the most stable sections of beach in the park. 

CONCLUSIONS 

 The beaches within KAHO, although they only extend 4 km in length, form a very 

dynamic and complex system. Two distinct types of beach occur within the park 

bounds:(1) a tidal-dominated intertidal beach, and (2) a storm-dominated perched 

beach. A linear regression shoreline change analysis, conducted using seven dates of 

georeferenced aerial photographs between 1950 and 2002, indicates that there is a 

consistent erosional trend in the park, with an average annual rate of -0.3 m/yr. The 

shoreline erosion is likely a combined result of the rise in annual mean high water and 

the subsidence of the island due to the loading from the active volcano. The shoreline 

erosion rate appears to be in a state of dynamic equilibrium, whereby the average rate 

is periodically punctuated by episodes of order-of-magnitude increases in the erosion 

rate, or even reversal to an accretional trend, followed by a return to the average. 

These periods of distinct variation from the average rate possibly represent a climatic 

signal (i.e. periods of more frequent Kona storms or higher than normal sea levels) 

within the average data; this will be explored in future analyses. 

The shoreline change study is supplemented by a beach area analysis that, 

similar to the shoreline change analysis, shows a system that is in an equilibrium state, 

punctuated by periods where the beach area nearly doubles in size. This suggests that 

either there is a volumetric increase in the amount of beach material during the periods 

of greater beach area, or that the amount of sand is simply being spread over more 

area (and therefore thinner) during periods of increased wave energy. In either case, 

the system returns over a few years to the equilibrium state. Based on this analysis, the 

beaches are currently in a state of returning to an equilibrium area following a period of 

increase in area in 2002. Thus, continued loss of beach area may be expected over the 

next few years.

A beach stability map was developed from the polygons of beach areas to 

conceptualize the spatial consistency of the presence of a beach in any given location. 

Based on the seven dates of photographs, the map shows areas where the beach has 

been present during all, or most time periods and thus is stable, versus areas where the 

beach has only existed during one or two dates and is thus considered much more 

ephemeral or unstable. Inconsistencies between the beach stability map and the 

shoreline change rates show that identifying erosion hotspots based solely on a 

shoreline change analysis may lead to erroneous conclusions. The beach stability map 
provides a valuable tool for effective management of park resources as managers can 

now identify stable areas in which to focus efforts such as habitat preservation or 

infrastructure development that will sustain the least erosional impact in the future.

Future studies should include investigations into the geomorphic controls on the 

stability, such as elevation, topography, or geologic controls such as flow age or texture. 

ACKNOWLEDGEMENTS 

We would like to thank Sallie Beavers and Stan Bond of Kaloko-Honokohau 

National Historical Park for valuable logistical assistance. T. Reiss (USGS) provided 

excellent survey support and field assistance, and A. Gibbs (USGS) and C. Storlazzi 

(USGS) provided invaluable suggestions regarding data analysis methods. Randy 

Nagle (NPS) performed the georeferencing of the aerial photographs. Josh Logan 

(USGS) provided helpful graphics. This study was funded by the USGS Coastal and 

Marine Geology Program and the National Park Service. 

REFERENCES 

Chorley, R.J., Schumm, S.J., and Sugden, D.E., 1984. Geomorphology. London, 

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