57

MONITORING THE NOURISHED SANDLONGSHORE MOVEMENT BASED ON
FELDSPAR LUMINESCENCE MEASUREMENTHAIJIANG LIU1, AYUMI HAMAMOTO1, SHINJI SATO1
1.

Department of Civil Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-8656, Japan. hjliu@coastal.t.u-tokyo.ac.jp.

Abstract:

In this study, monitoring the nourished sand longshore movement
was conducted based on the feldspar luminescence measurement, including both
Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL).
Nourished sand presents larger TL/OSL properties than the natural beach sand.
Investigation on the spatiotemporal distribution of post-filling beach sandluminescence features at the Miyazaki coast and the Shounan coast, Japan, provides
a new approach to evaluate the nourished sand movement characteristics.
Comparing these two techniques, it is confirmed that the OSL is suitable for study
on short-term sediment movement within a limited area; whereas, TL can be applied
to the long-term and large-scale nearshore process assessment.

Introduction
In these years, beach nourishment has been increasingly applied as acountermeasure against coastal erosion problems. Different from coastal
structures, e.g., seawalls and breakwaters, periodical artificial beach
replenishment, introduced as a soft coastal defence scheme, has been widely
regarded as an environmentally acceptable approach to the beach and dune
protection (Hanson et al., 2002). However, up to now, the evaluation on thebeach nourishment is mainly based on the bathymetry surveys, which areindirect, costly and normally carried out with an annual frequency. Considering
the low temporal and spatial resolutions of the collected data, this method is not
appropriate for examining the detailed coastal processes since the nearshoremorphology is highly dynamic which, in general, is significantly modified by theepisodic storm events. Other methods include applying fluorescent or dyemarked tracers in the target field. These approaches are laborious and timeconsuming with respect to the tracer counting after filed samplings. At the sametime, assessment on the nourished sand movement is difficult to achieve due tothe mixing feature between the nourished and natural sands.
Recently, Rink (1999) and Liu et al. (2009a, b) suggested the use of naturalresidual thermoluminescence properties of quartz and feldspar grains as a

58possible transport indicator in the study of various coastal morphodynamic
processes. In this approach, the nearshore sediment movement is directly
investigated through the natural beach sands, as self-tracers, by focusing on theirinternal luminescence properties. This approach allows more reliability related to
the field investigation on analyzing the corresponding coastal process. In thisstudy, such technique was applied in monitoring and tracing programs following
beach fills. Results show applicability of this approach for evaluating the
temporal and spatial nourished sand distributions after beach nourishment
implementation. In addition, nourished sands movement patterns were identified,
especially after the extreme events.
Luminescence
In a sedimentary environment, quartz and feldspar particles undergo naturalradioactive process. This induces the electron ionization in the grain crystal lattice
due to the natural nuclear radiation effect, which builds up the latent luminescencesignals in constituent mineral grains. The magnitude of luminescence signals in agrain is proportional to the accumulated energy obtained during the depositional
burial. These accumulated internal luminescence signals can be stimulated bycertain external energy, such as heating or exposure to the light. The signal released
after the heating process is termed Thermoluminescence (TL); whereas, the lightstimulated luminescence signal is named as Optically Stimulated Luminescence(OSL). A detailed description can be referred to Aitken (1998). After sand particles
are moved from their original sedimentary area, light exposure is accompanied withsand movement along the river and nearshore zone, which causes the reduction ofparticle luminescence signals.
In Japan, the predominant materials used for beach nourishment come from thedepositional sediment stored on the riverbed or trapped inside the upstream dam
reservoir of the nearby river. Liu et al. (2009a, b) applied the TL technique toinvestigate the nearshore sediment transport process in the Tenryu-Enshunanda
fluvial system, and they found the riverine feldspar particles contain larger
luminescence signals than coastal sands. Therefore, in case of a erosive coastal
area that has virtually no input of sediment from other sources except the beachnourishment, investigation on the spatiotemporal distribution of beach sandluminescence signals in the vicinity of nourished spot could provide an
opportunity for monitoring the nourished sand transport patterns. In this study,
considering the nourished sand as a transport indicator, measurement on theluminescence signals of field-collected sand samples was implemented. Both TL
and OSL techniques are adopted in this study for the inter-comparison andmutual confirmation on the experimental findings. When applying to investigate
the nearshore sediment movement, field applicability of these two approaches isalso specified using the sunbath test.

59

Research Area
Two typical coastal areas in Japan which are under regular beach fills are
considered in this study, i.e., the Miyazaki coast and the Shounan coast. During
the field survey, surface samples (about 10 cm beneath the ground surface) wereextracted in the intertidal zone along the target regions with a spatial interval ofseveral hundred meters. In order to identify the nourished sand luminescence
properties, sand samples were also collected from the residual bulk of artificiallyfilled sands at the relevant locations during the field survey. Sample collection
was carried out using opaque photographic film cases. Collected samples wereimmediately stored in the dark bag to avoid natural light exposure which may
induce the underestimation of luminescence signals.
The Miyazaki coastal area (upper panel of Fig. 1), facing the Pacific Ocean, is an
alluvial plain at the eastside of the Kyushuu Island, Japan, which formed after
the depositional process of sediments carried from the mountain area throughseveral dominant rivers in this region, such as the Hitotsuse River and the
Ooyodo River. However, over the last several decades, with the completion ofdams along the upstream river route, together with the overexploitation ofriverine sediments for construction works, sediment discharge from rivers was
reduced significantly. At the same time, harbors, airport runway and river mouth
jetties were set up along the coastal area, which changed the nearshore sediment
movement balance. All these anthropogenic impacts cause the coastal erosion
problem along the Miyazaki coast, especially between the Hitotsuse River andthe Ooyodo River. As a countermeasure against the erosion problem, beachnourishments were implemented at three locations along the target area since2007, i.e., Ishizakihama North (hereafter referred to as N-A), Ishizakihama
South (hereafter referred to as N2007 since it was carried out in 2007) and Zoo
Park (hereafter referred to as N-B) as illustrated in Fig. 1. Table 1 lists thegeneral information about beach fills at each location, which includes thenourished materials’ source, nourished sand size, beach fill period and amount.
Field samplings were conducted twice in Jul and Oct, 2009. During the fieldsurvey, it was confirmed that most of N2007 nourished sands have been flushed
out from their original location and mixed with natural beach sands. On the other
hand, there exists a series of steep coastal scarps along the natural shoreline
considering that the Miyazaki coast is highly erosive, especially after typhoon orstorm events. Photo 1 shows the post-typhoon T0918 beach situation at thelocation 2.6 km south of the Hitotsuse River in 2009. Steep coastal scarp with aheight around 6 m was formed, which indicates a large amount of scarp sands
was eroded and mixed with the natural beach sands. Contribution from scarp
sands should also be considered in case that beach sand luminescence signals areapplied in this study. Taking this into account, TL/OSL samples were also

60

picked up from the coastal scarps. From the recorded river water level data, it isconfirmed that no significant river floods occurred in 2009 which demonstrates
river sand supplies to the Miyazaki coast play a limited role to change thenearshore sand constitution during the study period.

N-A

Breakwater

N-B

N2007

Miyazaki Port

Seawall
Hitotsuse River

Ishizaki River

TL Intensity

100

TL: Feb, 2009

N-A

TL: Jul, 2009

N-A

(a)

10

1

0.1

TL Intensity

100

(b)

N-B

10

1

scarp sand
0.1
100

TL Intensity

TL: Oct, 2009

(c)

N-B

10

N2007

1

0.1

OSL Intensity

1000

OSL: Jul, 2009

100

N-A

N-B

(d)

N-B

(e)

10
1
0.1

scarp sand

0.01

OSL Intensity

1000

OSL: Oct, 2009

100

N2007

10
1
0.1
0.01
0

2

4

6

8

10

12

Distance from the Hitotsuse River (km)Fig. 1. TL and OSL intensity distribution along the Miyazaki Coast

14

61
Table 1. General information about beach nourishment along the Miyazaki Coast

Location

Nourishment
materials

Ishizakihama
North (N-A)

Ooyodo/Sanzai
riverine deposit

Injection
periodNourishedsand size(D50, mm)

Beach fillamount(×104 m3)

20072008

-

6.8

0.4

7.4

2009
Ishizakihama
South (N2007)

Ooyodo riverine
deposit

2007

-

2.5

Zoo Park(N-B)

Omaru riverine
deposit

2009

2.4

1.6

North

Eroded coastal scarp

Photo. 1. Post-typhoon T0918 beach situation at the location 2.6 km south of the Hitotsuse River
Old Nourishment
Sagami River

Old nourishment

Nourishment
Old nourishment

Old Nourishment

1 km

N

Chigasaki Headland
fishery harbor

Breakwater
Ooiso Port

Enoshima

100

100
Nourished sand TL
Beach sand OSL
Nourished sand OSL

Nourished sand

10

10
1

1

0.1
-5

0

5

10

15

Distance from the Sagami River (km)Fig. 2. TL and OSL intensity distribution along the Shounan Coast20

OSL intensity

TL intensity

Beach sand TL

62

As for the Shounan coast, similar to the Miyazaki coast, erosion problem occurs
due to the construction of coastal structures, e.g., harbor and headland, and dams
along the Sagami River, which is the predominant sediment source for thisregion. Field sampling was conducted in Sep, 2009 with locations shown in theupper panel of Fig. 2. A series of beach nourishments was carried out along theShounan coast to mitigate the erosion problem. During the field sampling, old
nourishments specified in Fig. 2 had been washed away from their original
locations. Only nourishment between the Chigasaki Harbor and the Headland
was remained at the time of field sampling.
Laboratory Measurements
After field sampling, sample pre-treatment needs to be performed before theluminescence measurement to obtain pure feldspar grains. Such pre-treatment
process is carried out in a dark room under the low intensity orange lighting
condition (600 nm) under which little influence on the inherent particle
luminescence signals is expected (Aitken, 1998). Initially, sand fraction with sizeof 180–300 µm is separated through wet-sieving. Subsequently, this fraction istreated with 15% H2O2 and 18% HCL to remove the organic material andcarbonates, respectively. Then, a density separation in sodium-polytungstate at adensity of 2.58 g/cm3 is used to obtain the potassium-feldspar–rich fraction,
which has a density between 2.53 and 2.58 g/cm3. After drying the samples
under the room temperature condition, a uniform layer of sands was mounted on
1 cm stainless-steel disc using silicone spray as an adhesive. A monolayer
aliquot with each disc containing about several hundreds feldspar particles, wasapplied to avoid the heterogeneous effect from individual grains. At eachlocation, four disks of sample aliquots were prepared and used for luminescencemeasurement. The averaged values are presented in the following discussions.
Luminescence measurements were performed on a Risø 48-sample automated
TL/OSL Reader (model TL/OSL-DA-20) with an internal 90Sr/90Y β irradiation
source. Sample TL signals were measured up to 5000C with a heating ramp rateof 50C/s. Sample OSL signals were recorded using the infrared stimulation for
100 s at a temperature of 500C. A detection filter combination of a Schott BG39
and Corning 7-59 filters was used with a luminescence signal transmission
window between 320 and 480 nm. This combination can effectively exclude
luminescence signals from any quartz and from most plagioclase feldspar during
measurements. These mineral components may remain in the feldspar fraction
even after the density separation.
TL measurements were performed based on the TL test protocol proposed by
Liu et al. (2009a). Normalization on the TL glow curve is achieved after

63

dividing the natural TL signals by the averaged value of 10.8 Gy test dose
induced TL signals over the temperature range of 200-4000C, which, asmentioned in Liu et al. (2009a), represents the predominant part of test dose TL
glow curve. In this study, the TL intensity is defined as the average value of thenormalized natural TL signals between the temperature range of 260-3800C,
which, as mentioned in Liu et al. (2009b), covers the principal natural TL
signals. As for OSL measurements, the test protocol is similar to the SingleAliquot Regenerative-dose (SAR) protocol used for luminescence dating(Murray and Wintle, 2000). In which, the preheat and cut-heat conditions are
determined from Ishibashi et al. (2009). Stimulation conditions used for OSL
measurement is the same as Wallinga et al. (2000) for feldspar OSL tests. Duller
and Augustinus (1997) argued that measurement of the initial OSL signal has theadvantage of using only that part of the signal which is most sensitive to light,
and of providing an enhanced signal-to-noise ratio. Taking this into account, thesignal used in this study is the OSL signal detected in the initial 2 s ofstimulation. Same as Wallinga et al. (2000), a background signal is subtracted
from the initial OSL signal, based on the average OSL obtained in the last 10 s.
This net signal is considered as the sample OSL response. The sensitivitycorrected normalized OSL intensity is estimated in terms of the OSL signal after
a fixed test dose (0.9 Gy artificial irradiation). Comparison on such TL/OSL
intensity among difference samples could be implemented regardless of thephysical (e.g., mass or shape) or intrinsic (e.g., irradiation or stimulation
responses) variations among different aliquots.
Results and Discussions
Miyazaki Coast
Fig. 1 demonstrates the TL/OSL intensity distribution along the Miyazaki coast
for sands collected at different time periods. Sato et al. (2009) also measured the
TL distribution along this area using field samples collected in Feb, 2009. Theirdata were reanalyzed and applied here for inter-comparison with results from thepresent study.
First, look at the nourished sand TL intensities at locations N-A and N-B (Figs.
1a, 1b and 1c), it is clear that TL intensity of the nourished sands is much larger
than the nearby beach sands. This is ascribed to the fact that nourished sandscome from the riverine deposits (Table 1), which contain large luminescenceintensity. At the same time, TL intensity at N-B, riverine sediments from theOmaru River, is much larger than N-A, extracted from the Ooyodo River. Thisreveals the different geological sediment luminescence characteristics between
these two rivers, which are in agreement with the finding in Sato et al. (2009)

64

who measured TL intensities of these two riverine samples. After the nourishedsands are placed at the designed coastal beach filling spot, their luminescence
properties, in general, keep unchanged if they are not moved by waves (no light
exposure). This is also confirmed in Fig. 1. At location N-A (N-B), TL
intensities are almost the same between Feb and Jul (Jul and Oct). Furthermore,considering the OSL properties of the nourished sands (Figs. 1d and 1e), sameconclusions can be obtained, i.e., nourished sand OSL intensity is larger than the
nearby beach sand; N-B sands present a larger OSL signal than N-A sands; no
significant change on N-B sand OSL intensity between Jul and Oct. Previous
nourishment sand samples (N2007) were also collected in Oct field survey. As
mentioned previously, almost all N2007 sands have been washed away fromtheir original placement location. In Oct survey, only two samples of
suspiciously untouched N2007 sands (with possible light exposure) werecollected and analyzed. Results are shown in Figs. 1c and 1e. Taking into
account that N2007 sands come from the Ooyodo River, the same as N-A, andcomparing with N-A in Figs. 1b and 1d, both TL and OSL intensities are smaller
for N2007 samples. This indicates that different from the N-A and N-B
nourished sands which are still massive and heap together at the time of fieldsampling, these N2007 sands, generally in the form of small segments, may be
exposured to sunlight after the placement in 2007. At the same time, considering
the small residual amount of N2007 sands, their influence to the beach sandluminescence features can be neglected.
Subsequently, coastal scarp sands were sampled in Jul at locations about 7 km.
In Fig. 1b, measurements show small TL intensities (about 1) for these scarp
sands, which are almost the same as natural beach sands. From Miyazaki Coast
documents 2009 (http://www.qsr.mlit.go.jp/miyazaki/html/kasen/sskondan), it isconfirmed that such coastal scarp is generated after erosion of the old sand dune,
which was formed with a time scale of thousand years by the wind-blown beachsands. Owing to the aeolian environments that such sand experienced,
luminescence signals are almost bleached completely before deposition andburial in the sand dune, especially for OSL signals. In general, coastal dunesands present rather small luminescence intensities (Liu, et al., 2009a).
Considering the fairly weak natural radiation dose to the beach sand (0.5-1.0 Gy
per thousand years, Rink, 1999), 1,000-year burial of such dune sand may only
increase particle inherent luminescence signals by 1 Gy. Comparing to the test
dose used for TL normalization in this study (10.8 Gy), 1 Gy of luminescencesignal is insignificant in the measured TL intensity obviously. This explains thereason why scarp sands reveal a similar TL intensity as the natural beach sands.
On the other hand, since test dose used for OSL normalization is only 0.9 Gy, 1
Gy increase in luminescence signals after sand dune burial do enhance the scarp
sand OSL intensity by a value of 1. As shown in Fig. 1d, scarp sands presents an

65

OSL intensity about 1, which is larger than the beach sands whose OSL are only
about 0.1. Comparing with the fairly large nourished sand OSL intensity (around100) and considering the quick decaying feature of OSL signals as mentioned
later, influence from scarp sands to the beach sand luminescence properties still
plays a minor role.

a. Feb

Nourished sandc. Julconcrete blocks

Seawallsampling point
sampling pointc. JulNourished sandsampling pointd. OctNo nourished sandsampling point

Photo. 2. Various field sampling situations

After checking both nourished and scarp sands luminescence properties as thetwo main possible sand sources for the Miyazaki coast, it is further confirmedthat only nourished sands provide large luminescence intensity to the nearshorearea, which can induce modification on the longshore beach sand luminescencesignals. Hence, after looking at the spatial distribution of beach sandluminescence intensities, longshore movement of nourished sand can bedetected. In Fig. 1a, beach sand TL intensity keeps a rather constant value (about
1) in the target region, which is smaller than the nourished sand TL intensity.
Photo 2a presents beach sand sampling situation in front of N-B in Feb. It isclear that in Feb, nourished sands were remained at backshore, far away from thenormal wave actions. Hence, nourished sands were not touched and mixed withnatural beach sands. Accordingly, there is no clear modification on beach sandluminescence features in Feb. Significant transport of nourished sands, ingeneral, occurs mainly during high wave conditions, such as storm and typhoon.
Fig. 1b illustrates the TL distribution in Jul. Obvious longshore variation can be66

observed. Taking results at the south of N-B into account, they present TL
intensities larger than the corresponding Feb samples in Fig. 1a. This is ascribedto the contribution from nourished sands at N-A and N-B which were transported
southwardly by the May storm. Fig. 3 demonstrated the temporal distribution ofwave height at the Miyazaki coast in 2009 and longshore transport rate estimatedby the CERC formula. A severe storm with significant wave height more than 6m attacked this area on May 28 as shown in Fig. 3a, which induced significant
southward longshore sediment movement (Fig. 3b). Nourished sands at N-A andN-B were transported by the May storm and stored in between the seawall andshore-parallel concrete blocks. Photo 2b shows Jul beach sand sampling
situation in front of the seawall. Different from the natural beach, e.g., region
between N-A and N-B, where sands were successively exposed to light by daily
wave actions which reduce the nourished sand luminescence signals, samplingarea in between the seawall and concrete blocks is sheltered and protected bythese structures, which suppress the sand movement and avoid light exposure
under normal waves. As a result, after nourished sands reach here, their large
luminescence features can be preserved and detected in Fig. 1b. Large OSL
intensity is also obtained at this region in Jul as shown in Fig. 1d. In Figs. 1b and1d, large luminescence intensities are also confirmed at region between 7 and 8
km. Considering the values are even larger than N-A, it proves that such large
TL/OSL values do not come from the contribution of nourished sands at N-A
which, although, were moved here during May storm. Nourished sand at N-B isconsidered to be the only source to introduce such large luminescence signals.
Photo 2c presents beach sand sampling situation in Jul. Comparing with Photo2a, it is clear that beach erosion occurs during this period and in Jul, and that
nourished sand at N-B was eroded and moved by the daily normal waves which
mixed N-B sands with original beach sands and increased the luminescencesignals. Fig. 3c illustrates the hourly longshore sand movement pattern aroundthe time of Jul sampling. Northwardly longshore sand movement is confirmed
then, which illuminates the reason of the large TL/OSL values at location
between 7 and 8 km. These large TL/OSL values reduce further northward whichindicates contributions from N-B gradually disappear. On Oct 7, a Typhoon
T0918 with significant wave height of 7.8 m attacked this region which causes
significant northwardly sand movement illustrated in Figs. 3a and 3b. After
T0918, most nourished sands at N-B were moved away as shown in Photo 2d.
Measured beach sand TL/OSL intensities around N-B present the natural beachsand values (Figs. 1c and 1e). One luminescence peak was confirmed at location
5.7 km, which is owing to the contribution from nourished sands at N-B thatwere transported here during T0918. At other locations, large TL/OSL values are
not detected. This may be due to the specific local configuration at location 5.7
km. This location is the conjunction point between the vertical and mild-slope
seawalls and there is a jetty made of concrete blocks penetrating into the sea

67

Wave height (m)rate (m /s)

5
3
1
-1
-3
-5

3

10
8
6
4
2
0

(a)

1

2

3

May
storm
4
5

6

Southward

7

Feb sampling
Northward
1

2

8

T0918
9
10

11

12

3

4

Jul sampling
5

6

1

(b)

Month

7

8

9

Oct sampling
10

11

12

1

Month
Month
3

rate (m /s)

Longhsore transport

Longshore transport

which can trap northwardly moved sands to its south. Therefore, a certain
amount of N-B nourished sands stored at this location where longshore sediment
movement is blocked and sheltered by the structures. Light exposure at thislocation is therefore limited. Hence, large TL/OSL values are preserved here. On
the other hand, the nourished N-B sands deposited at other locations after theT0918, lose their inherent large TL/OSL features since successive nearshore
sand movement is undergoing before Oct sampling during which sand particles
experiences continuous light exposure.

0.1
0.05
0
-0.05
-0.1

Southward

Jul Sampling

(c)

7/10

7/11

Northward
7/9

7/9

7/10

Date

Fig. 3. Temporal variation of significant wave height and longshore sand transport rate estimated fromthe CERC formula along the Miyazaki Coast in 2009

Further look at the spatial variation of TL and OSL signals, e.g., Figs. 1b and 1d,
it is found that changing of OSL signal is much more significant than TL. For
instance, between beach sand at location 7 km and nourished sand at N-B,
decrease of TL intensity is in an order of 10; whereas, OSL intensity reduces by
a factor of 1000. Considering that the travelling distance or light exposure
experience is the same for these two tests, the above result indicates that sand
OSL signal is more sensitive, and OSL signals reduces more rapidly to the light
exposure (longshore sand movement) than TL. This is further confirmed fromthe sunbath test. Fig. 4 presents the sunbath test results for both TL and OSL
which is conducted by exposing the treated natural feldspar samples to sunlightfor different durations. Although different from the field conditions (sunbath test
provides much efficient light exposure than the field situation), it is clear thatwithin one day, OSL intensity reduced to only 9 percent of its original value. As
for TL, it takes a much longer time, 13 percent of its original value remains even

68

after two weeks sunbath. Taking this into account, it shows that OSL
measurement is preferable for investigation on the short-term (event-induced)
nearshore sediment movement within a limited area (local problem). On theother hand, TL measurement can be applied to a wide nearshore area to estimate
a relative long-term sand transport pattern as demonstrated from studies in Liu
et al. (2009b).
20

TL/OSL Intensity

16

OSL

12

8

TL
4

0
0

5

10

15

Sunbath Time (day)Fig. 4. Sunbath test for TL and OSL samples

Shounan Coast
Fig. 2 illustrates the luminescence signal distribution along the Shounan coast.
Comparing with beach sand, nourished sand between the Chigasaki Fishery
Harbor and the Headland reveals large luminescence intensities, which also
increases the adjacent beach sand TL/OSL values. Nourished sands were mixing
with original beach sands by daily waves during the field sampling. However,such influence is restricted within this local area due to the longshore movement
limitation by the nearby coastal structures. In general, erosive spots present low
TL/OSL intensities, e.g., at locations 1.5 and 5.6 km. At these locations, beachsand movement is remarkable which results in more opportunities for sandparticles to the light exposure and reduces their internal luminescence properties.
At the same time, relative large TL/OSL values are observed at sand accretional
areas, e.g., behind the breakwater and at the west side of the Enoshima island.
Taking into account the old beach nourishments implemented at Shounan coastas illustrated in the upper panel of Fig. 2, large TL/OSL values may represent theeffect from these old nourished sands. These sands have large luminescencesignals and after their deposition in the vicinity of structures, such signals are, in
general, preserved owing to the limited sand movement owing to the shelter ofcorresponding coastal structures.

69

Conclusions
In this study, monitoring the nourished sand longshore movement at the
Miyazaki coast and the Shounan coast was performed based on the feldspar
luminescence measurements, including both TL and OSL techniques. The main
conclusions are summarized as follows
1.

Nourished sands from the riverine deposits present much larger TL/OSL
properties than the native beach sands. Therefore, investigation on thespatiotemporal distribution of beach sand luminescence features provides
an opportunity for assessment on the nourished sand transport patterns.

2.

Along the Miyazaki coast, eroded scarp sands exhibit small luminescencesignals which are almost the same as natural beach sands since these scarp
sands consist of old wind-blown coastal dune sands.

3.

Longshore sand movement at the Miyazaki coast after May storm/typhoon
T0918 is revealed from beach sand luminescence measurements on Jul/Oct
samples. Dominant southwardly longshore sand movement after May storm
is confirmed with large TL/OSL values being detected in between theseawall and shore-parallel concrete blocks. The luminescence peakobserved at location 5.7 km in Oct test corresponds to the northwardly
longshore movement of N-B sands after the T0918. Large luminescencefeatures at location 7 km in Jul test comes from N-B sands, which wastransported there by daily normal waves at the time when conducting the
Jul field sampling.

4.

Comparing between TL and OSL results, as well as the sunbath test, it isconfirmed that sand OSL signal is more sensitive to the light exposure or
longshore sand movement than TL. Accordingly, OSL technique ispreferable for investigation on the short-term (event-induced) nearshore
sediment movement within a limited area (local problem). On the other
hand, TL technique can be applied to a wide nearshore area to estimate a
relative long-term sand transport pattern.

5.

As for the Shounan coast, influence from the nourished sand was confirmed
though the TL/OSL measurement. Erosive spots present low TL/OSL
intensities; whereas, sand-accumulated areas show relatively large values,
which is ascribed to the old nourishment.

70

Acknowledgements
This study is financially supported by the Kajima Science Foundation.
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