Subsidence,, Mayy 1991) 1991) .. IAH IAHSS ~ Publ no. 200,1991.hydrologie.org/redbooks/a200/iahs_200_0081.pdf · 2015-01-16 · S. Liao et al. 82 Lili River, and Peishui River with

Land Subsidence (Proceedings of the Fourth International Symposium on Land Subsidence, May 1991). IAHS ~ " , May 1991). IAHS Publ. no. 200,1991.

The Monitoring and Investigation of Ground Subsidence in Southwest Taiwan

J. S. LIAO & K. L. PAN Energy and Resources Laboratories, Industrial Technology Research Institute, Bldg 64, 195 Sec. 4, Chung Hsing Road, Chutung, 31015 Hsinchu, Taiwan, China B. C. HAIMSON Geological Engineering Program, University of Wisconsin-Madison, Madison, WI 53706, USA

ABSTRACT The overwhelming fluid withdrawal into fishery farms has caused a serious subsidence at Linpien, Chiatung, and Shuitiliao, the districts located at Southwest Taiwan. To figure out the relations between the current subsidence and decline of water level, several monitoring systems including multipoints wire-flex extensometer and multilevel water-head monitoring system have been installed in the area investigated. Meanwhile, the on-site borehole drilling and laboratory soil tests are also conducted to provide the soil properties data. The behavior of subsidence incurred by the decline of water head is predicted by the improved Biot's three-dimensional consolidation theory through computer simulation. The results show that the subsidence rate in the investigation area has been gradually alleviated. Ground subsidence incurred by the decline of water level can be fairly predicted from the mathematical modeling.

INTRODUCTION

The occurrence of major land subsidence due to the withdrawal of groundwater is relatively usual in highly developed areas, such as the cases at Shanghai in Mainland China, Taipei Basin in Taiwan, Cheshire district in Great Britian, Po Delta and Venice in Italy, Tokyo and Osaka in Japan, Mexico City in Mexico, Bangkok in Thailand, San Joaquin Valley and Santa Clara Valley in the United States, Wairakei in New Zealand, Far West Land in South Africa and Latrobe Valley in Australia, etc. (Poland, 1984). In general, the subsidence in these districts is mainly due to over-withdrawal of fluid, while the effects of natural factors, such as tectonic effects on subsidence is not significant. For instance, the subsidence in the east coast of America is approximately 2.5 mm/yr due to the raising of seawater (Davis, 1987); the crustal movements in Taiwan Geosyncline causes a 5 mm/yr raising in the Coast Mountain Chain, and a subsidence in the Coastal Plain in western Taiwan (Pingtung Coast Plain is included) (Chern, 1984). In Taiwan, ground subsidence in Taipei Basin, which began in mid-1950's has caused great concern during the past two decades. Besides Taipei Basin, the Choshui River Alluvial and Pingtung Coastal Areas are other hot-spot areas in. which there has occurred tremendous ground subsidence due to withdrawal of groundwater to fishery farms. The action of withdrawing groundwater has led to piezometric head decline in confined aquifer, that, thus, increases the effective stress in earth materials. The Pingtung Coastal Area, geologically being the Lili River Alluvial Fan, circled by Linpien River,

81

/. S. Liao et al. 82

Lili River, and Peishui River with a area of 73 km2, has the withdrawal of groundwater, 165 x 106 m3/yr, which is equal to average amount of withdrawal of 6.19 mm/day (Yang, 1987). Due to the large amount of water withdrawal and an uncompacted sediments (fine grains) distribution in the area, the subsidence is, generally, greater than those expected. The contour lines of land subsidence in the Pingtung Coastal Area is illustrated in Fig. 1. The maximum ground subsidence occurs at Wenfong where the accumulated subsidence has been over 2.43 m during February 1970 to June 1988 (TWCB.1988).

A subsidence monitoring well (ERt)

Q subsidence monitoring wen (TWC8)

FIG. 1 The contour lines of land subsidence in the coast of Pingtung County (TWCB, June 1988).

The geological materials in the area are composed of various types of soil, they are SM (silty sand), SP-SM (sand to silty sand), SP-SC (sand to clayey sand) and SC (clayey sand). The grain size distribution ranging in 0.3 to 0.03 cm is ranked between fine sand and silt (ERL, 1988). The thickness of alluvium at Wenfong and Shuitiliao is in the range of 165-200 m. To understand the relations between the change of water level and ground subsidence, some monitoring systems, such as multipoints extensometer and multilevel water-head piezometer were installed at Linpien, Wenfong and Shuitiliao and mathematical modeling was also conducted to approach these relations.

The investigation area in this paper covers Linpien and Lili River allvial fan including Chiatung and Shuitiliao. Numbers of studies including the analyses of hydrogeological data, field measurements and mathematical modeling have been carried out in this area to investigate the ground subsidence.

SUBSURFACE GEOLOGY AND HYDROLOGY

The major structure in this region is Chaochou fault, located at eastern part of the

83 Ground subsidence in southwest Taiwan

investigation area, which is a high-angled reverse fault with a dip of 75° - 80° eastward. Raising block of stratum is in the east of the fault plane. The downward faulted block with a striking of NNE-SSW formed Pingtung anticline and syncline. The topographic and geophysical data show that this region is currently in subsiding due to tectonic force (Chern, 1984). The subsurface geology of this region is identified from the borehole logs and rock/soil mechanical properties data. The reading of Gamma-ray log, generally, is less than 40 cps in this area (ERL, 1988). The contrast between high readings and low readings of Gamma-ray log is not significant. Core logs data show that the formation in the area is a type of the sand or sandy argillaceous formation formed by the erosion of river. It seems that the formation is uncompacted and has a high porosity.

HISTORY OF LAND SUBSIDENCE IN SOUTHWEST TAIWAN

The rate of subsidence in the coastal plain of Southwest Taiwan, is approximately 0-3 cm/yr during 1914-1979 (Chern, 1984); however, the raising rate is only 2-5 mm/yr based on the study of geomorphology (Hsu, 1954, 1962, 1980; Hsu & Chai, 1974; Li, 1976) and radiometric dating (Konishi, Omura & Kimura, 1968; Peng, Li & Wu, 1977; Taira, 1975). Obviously, the raising rate of ground is much less than the subsiding rate in the Southwest Taiwan. To be concluded, the withdrawal of groundwater might not be the only cause of ground subsidence in the Southwest Taiwan, but was being a major cause.

The historical data of elevations of various bench marks in the Pingtung Coastal Area is illustrated in Fig. 2. The accumulated land subsidence amounted to 2.43 m, from February 1970 to June 1985, was found at Wenfong.

l-t M M Wuiong

East

Tungkong

Chlatung Shult l l lao

Ltnpten ) Pelchlwel / Fungltao wel / Funglt Nansulhu

1 original

bench mark number

FIG. 2 The historical data of elevations of various bench marks in the Pingtung Coastal Area (TWCB, June 1988).

It is explainable since Wenfong has the highest soil compressiblity, Cc, among the three districts, while Cc = 0.4 at Wenfong, 0.3 at Shuitiliao, and 0.2 at Linpien(ERL, 1988). The subsidence has been recorded at there since January 1979. The subsidence rate was found accelerating during January to June in 1981, the beginning stages for


over-withdrawal groundwater in the Southern Taiwan, recording the amount of 5 cm/month for land subsidence (Lin, 1986). As noted previously, the over-withdrawal of groundwater for a long time has resulted in a lowering groundwater level and severe land subsidence. The viewpoint might be proved by the following facts: the area of fishery farm increased from 6 hectares in 1972 to 980 hectares in 1982. Wells have being increased rapidly responding the expansion of fishery farm. For example, the number of illegal wells in the groundwater restricted districts of Pingtung County is about 3871 (conservative estimation). The annual consumption of groundwater in this area is about 320 x 106 m3 in 1983, of which, approximately 176 x 106 m3 is for the purpose of the fishery farms (Lin, 1986).

The whole picture of the stratigraphie profiles in this region is illustrated in Fig.3.

FIG. 3 Stratigraphie cross-section in the Pingtung Coastal Area.

The abbreviations in Fig. 3 are represented by the followings: TS= Taiwan Sugar Company, WCC= Taiwan Water Conservancy Council, WF= Wenfong, WZ= Wentz Elementary School, CT= Chiatung. The Chaochou fault is crossing between 1-2 and 1-3. The Lili alluvial fan aged in Quaternary, is composed of uncompacted gravel, boulder, sand, silt and clay, etc. Around this area, boulder and gravel distribute toward inland; gravel, coarse sand and clayey sand distribute in the central region of the fan. The minerals in the shallower formations (less than 100m) in the area are composed of chlorite, illite and other non-swelling clay minerals with litter amounts of swelling clay minerals (ERL, 1988). It is, thus, concluded that there is not a significant influence of swelling clay minerals on ground subsidence in the shallower formation. The clay layer is thicker near seashore. The clay layer with a maximum thickness of 80 m, is located near seashore and west of fault. The gravel is thin at east of fault; it becomes thicker at west of fault and disappears at middle part of the area. Generally, the apex (#1) and middle part (# 13,14 and 25) of alluvium is a free water area; the end of alluvium (#18,28 and 20) is a semi-confined water aquifer; coastal plain (#21-26) is a confined aquifer (Chang, 1985). The resistivity logs show the salinity of groundwater is decreasing with increasing depth (ERL, 1988), it means the shallower formation might


be intruded or polluted by seawater. The change of groundwater level in rainy season (Sept. 1984) and dry season (April

1985) is in the range of 25-30 m at apex of alluvial fan, and 7-12 m near sea shore (Chang, 1985). To realize the variation of groundwater quality and seawater intrusion, the conductivity of groundwater was measured through the area in the shallow formation during sept. 1984-April 1989 (Fig. 4).

FIG. 4 The distribution of groundwater conductivity in the shallow formation (10m-50m).

Generally, the formation could be thought as intruded or contaminated by seawater if salinity is higher than 2000 micro ohm/cm. Since the well-water around Linpien River (ERL #1, #2) was recorded a high conductivity, which is 7000 and 19000 micro ohm/cm, respectively, the groundwater at shallower formation, around depth 30m, nearing coast was possibly intruded or contaminated by seawater and the confined water aquifer at deeper formation is still kept uneffected.

CONCEPT OF AQUIFER SYSTEM AND THE MATHEMATICAL MODELS

The water-head data (see Fig. 11) show two aquifers separated by a fine-grained interbed (sand with clay) at Wenfong. This conclusion can be proved by the geological core logs (ERL, 1988). Generally, due to the aspects of uncompacted formation and the thinning of clayey formation, it is reasonable to assume that the water flow in beds, is mainly, restricted in vertical direction. The aquifer systems in the investigation area, are thus, simplified to a single aquifer system with different lithologies.

The mathematical model based on the improved Biot's consolidation theory (Biot, 1941) is used to predict the relations between groundwater level and ground subsidence. The model is shown as follows (Liao & Haimson, 1989):


An incompressible solid and fluid field equation (see equations 3 and 4) can be modified to a compressible solid and fluid field equation. Equations 3 and 4 are based on the Biot's theory (Biot, 1941) which was formulated for solid-fluid interaction. According to Biot's theory, the soil skeleton is treated as a porous elastic solid and the laminar pore fluid is coupled to the solid under the conditions of compressibility and continuity. Biot's theory assumes some basic material properties including isotropy of the material, linearity of stress-strain relations, incompressible water in the pores, and water flow in the porous media according to Darcy's law.

The derivation of equations 3 and 4 is based on the following equilibrium and continuity equations in the absence of body forces (Smith, 1982):

K R + K X = f (1)

K T ^ - K X = 0 c 3t P

where X = fluid potential R = displacement vector f = applied external force t = time Km = elastic stiffness Kp = fluid stiffness Kç = coupling matrix ; Kc is the connection matrix that has the same shape

functions as the solid element governing the variation of pore water pressure within the element and the variation of displacements. The formula for K„ is as follows:

Kc= [VOL . NT dxdy (2)

then, the following formula for composite continuum (solid + water) was presented (Smith, 1982):

G x K x R . + 9 x K x p = m l c 1

( 9 - 1 ) x K x Rn + ( 0 - 1 ) x K x p + f (3)

6 x KT x R. - G2 x At x KD x p = c 1 P i

9 x KTc x R0 - 9 ( 9 - 1 ) x At x Kp x p (4)

where 9 = time stepping interpolation parameter At = increment of real time p = pore pressure

0 = initial time (beginning of time step) 1 = after initial time (end of time step) N = shape function (see equations 9)

VOL = volumetric strain (see equation 15) In the axisymmetric case, the stiffness for solid, liquid, and coupling matrices can be written as


Km = 2 K J J UT D U r dr d /

where U is strain-displacement matrix and D is elasticity matrix.

Kp = 2 ji J J DERIVT x KAY x DERIV r dr d/

(5)

Kc = 2 * l f VOL x N r d r d /

where N is a shape function for the quadrilateral element and r and f is polar coordinates.

N = [ Nj N2 N3 N4 ]

N 1 = 0 . 2 5 ( 1 - E ) ( 1 - T I ) N 2 = 0 . 2 5 ( 1 - \ ) ( 1 + T I ) N 3 = 0 . 2 5 ( 1 + | ) ( 1 + T I ) N 4 = 0 . 2 5 ( 1 + Ç ) ( 1 - T I )

where Ç and r\ are natural coordinates. The explicit form of the elasticity matrix D can be written as:

(6)

(7)

(8)

(9)

D E ( l - v )

( l + v ) ( l - 2 v )

1

v 1-v

1-v 1

0

0 1-v

v 1-v

V V

1-v 1-v

l-2v

2(l-v)

0

(10)

for plane strain and axisymmetry. Only the first 3x3 portion indicated will be employed in the plane strain case. The strain-displacement matrix, U, is a function of the natural coordinates in isoparametric elements.

U = AN where

(11)

/

A =

V

3r

0 •£-

d_ dz I r

0

a_ 9z

dr

- 0

(12)

/. S. Liao et al.

and

KAY = \ o 1 0 Kyj

DERIV = = m 4 x

aNT

aÇ

aN1

aîi

VOL = [ 3Nj 3Nj 3N2 3N2 9N3 9N3 9N4 9N4

9x 9y 3x 9y 9x 9y 9x 9y

(13)

(14)

(15)

Equations 3 and 4 are only valid for full saturation and incompressible fluid and solid (Smith, 1982). However, it is necessary to consider the incompressible fluid and solid as a compressible fluid and solid in the real situation. For the compressible solid case, equation 7 can be written as (Ghaboussi &Wilson, 1973; Rice & Cleary, 1976; Detournay & Roegiers, 1987):

K TtjJ a VOL" x N r d r d / (16)

where

a = ' 3 ( v u - v )

B ( l + v J ( l - 2 v ) (17)

In equationl7, vu is undrained Poisson's ratio and B is Skempton's coefficient, a is Biot's coupling coefficient. It measures the ratio of the water volume squeezed out to the volume change of the total medium if the latter is compressed while the water is allowed to escape. For incompressible solid grains, a = 1; for compressible solid grains, 0 < a < 1. Equation 6 can be modified to a case of compressible fluid by considering Biot's storativity coefficient, M:

0 x K* x R. c 1

6 x K. x P. - 02 x At x K x P L I P I

= 0 x K ' x R - 0 ( 9 - 1 ) x A t x K x P -c o v ' P o

0 xK. x P L o (18)

where KL can be written as (Ghaboussi & Wilson, 1973; Rice & Cleary, 1976):

with

K L J J jyj N 1 N r dr d/

M: 2 G B 2 ( l + v u ) 2 ( l - 2 v )

9 ( v n - v ) ( l - 2 v u )

(19)

(20)


where, G is shear modulus. For an incompressible fluid, M = «>, leading to KL = 0. Based on equations 3 and 18, after discretization in space, a time-stepping scheme for Crank-Nicolson type of approximation (0 = 0.5) has the form:

K K m c T At

K1 - ( _ _ K P + K. ) c v 2 P L ' - K - K

m c T At

K1 — K D - K , c 2

p L

(21)

Based on a hybrid method which set 9 = 1 (fully implicit) for the equation 3 and 0 = 0.5 for equation 18 can lead to the following equation:

K K m c T At c v 2 " L

0 0 T At

K — K D - K . c 2

p L

{":}

Here, let

IL

K K

T At K - ( ~ - K D + K . )

-{:,} Kr

K*

0

At 2 - K p - K L l

(22)

(23a)

(23b)

(23c)

(23d)


Cl (23e)

then, equation 22 becomes

K E 8I = K D S

0 + f ( 2 4 )

By solving equation 24 for unknown dl, displacements and pore pressure at each node can be determined.

The physical data input in the problem are shown in the Table 1. The elastic modulus, Poisson's ratio (drained), and permeability are determined from the laboratory tests, while the undrained Poisson's ratio and Skempton's coefficient are based on the estimation. The averaging water-level in the area was from 2m in Wantang to 26m in Linpien counted from ground surface during August 1985 to May 1987. In order to formulate a boundary value problem for analyses, it is necessary to define the following items: (a) the geometry; (b) the materials; (c) the loads; and (d) the boundary conditions. The mesh is divided into three different lithologies ranging from silty sand to clayey sand with a concave water-level (Fig. 5). The bottom of the mesh is constrained.

TABLE 1 Physical properties used in the mathematical model.

properties\ layers *A *B *C

elastic modulus (107 kg/m2)

Poisson's ratio (drained)

Poisson's ratio (undrained)

Skempton's coef. x-permeability (105 m/day)

y-permeability (105 m/day)

0.21

0.25

0.30

1.0 0.01

0.1

0.49

0.35

0.40

1.0 0.01

0.42

0.25

0.30

1.0 0.01

0.1 0.1

* A- loose silty sand; B- compacted silty sand; C- clayey sand

in the vertical direction and only vertical displacements are allowed on the sides of the mesh. The pore pressure on the whole boundaries is relaxed and only the gravity load is considered in the study. It shows, the more declining of the water level, the more subsiding of the ground due to that the rock (or soil) grain subjected to more overburden pressure. The magnitude from computer modeling (Fig. 6) is greater than (around 1.5 of) those from field measurements (Fig. 2). However, the trend for subsiding is approximately the same in both cases.


ntang

water level (1)

water level (2)

t

1

i:

c i:

f h

1

t C

Llnplen Chlatung

(A)

(B)

(C I

1

: . i t

Fuogtlac J

—

- -

i 1

3

Nans

FIG. 5 Finite element mesh in the Pingtung Coastal Area.

FIG. 6 Computational results from the mathematical modeling.

RESULTS OF FIELD MONITORING

Wire-flex extensometer (Fig. 7) with ten measured points is used to monitor the small deformations of the ground paralleling to the axis of borehole. The system designed by RocTest Inc. (Canada), is comprised of the three parts, which are

(a) mechanical head assembly (covering (1) to (4)) (b) rods and their protective tubing (covering (5) to (7)) (c) anchors ( (8))

The anchors are fixed individually to the rods. The array of rods is protected by an external sheath which is in contact with the cement grout and allows for some displacement in shear. The deformations measured are the differences between the

/. S. Liao et al

1. stainless steel tube

2. protective cap

3. rod guide tube

4 reference plane

5. spring steel rods

6. plastic tube

7. external polyethylene

sheath

8. steel anchors

FIG. 7 Wire-flex Extensometer.

in i t ia l reading 1 s t day reading

W V - I i T Ç V

ft) b

TT^V^ |

I» I t h d3y readlrv

jrjWK , ! mz

base rock

Assumptions: signif icance of reading:

l, spring steel rod • constant length

Z taking base plane as an in i t ia l reading

3. the deformation at the bottom of

rods is responded from those In

. reading per day b1 fth aay

Ww tops of rods

+ " : rebound

- ' : compression

^ anchor NO.

. subsidence based on In i t ia l reading

cf

. deformation of rods

d'n ' t^n * a * n * / - C

deformation in each sublayer

Û i 1 J 1 1

FIG. 8 Conceptual model for Wire-flex Extensometer.


movements of the deepest anchor and each anchor or head. The conceptual model is shown in Fig. 8. The Wire-flex system has been installed and started working since January 1988. The depth of key layer causing subsidence is expected in 50m counted from ground surface.

The subsidence of the individual layers can be observed clearly from multi-point wire line extensometer as shown in Fig. 9.

time (month, day)

FIG. 9 Deformation in each sublayer from Wire-flex Extensometer at Wenfong monitoring well.

The compression and rebound of earth occurs in the interval of 40-70m at Wenfong. The rebound might be due to the stop to withdraw groundwater. Both the rebounded upper soil and compressed lower soil occurred at Shuitiliao and Linpien are also located in the depth of 40 to 70m. The deformation started to occur during the raising period of water level(i.e., rainy period) while there is no significant change in sublayer deformation during dry period. Besides the effects of water fluctuation in rainy and dry period, the sickness of shrimps which have activated since 1989 causes a less use of groundwater, it, thus, slows down the subsidence rate. The conceptual design of multilevel water-head observation system using piezometer is shown in Fig. 10. The piezometer was installed at depth of 10 to 68m. Each different interval, under which measurements of subsidence are conducted, is isolated and separated by bentonite. There are two water levels identified at Wenfong (Fig. 11). The first aquifer, between 10 to 20m, is composed of sandy clay or sandy silt. The water pressure is close to static condition. It, thus, shows the interval between 10 to 20m is not a key layer for withdrawing groundwater. The water fluctuation in this layer is around 1 to 4 m. The second aquifer is between 25 to 65m. The water pressure at this depth is lower than'static pressure. Water fluctuation is more significant at this interval; it is, thus, projected that, the second aquifer is the key aquifer where the local resident is over pumping groundwater.

CONCLUSIONS

From the results of field monitoring, the subsidence rate in the investigation area has become alleviated since May 1988. The compression and rebound of earth are found at

/. 5. Liao et al. 94

i

protective cap

concrete plate

I?

r pvc pipt

filled back

• 40 cm bentonlte

- piezometer

40 cm bentonlte

- fil led back

- 40 cm bentonlte

- piezometer

- sand

- 40 cm bentonlte

FIG. 10 Diagramatic cross-section for the monitoring well of multilevel water-head.

around the depth of 40 to 70m. The ground is predicted to be stable in the near future if not over pumping groundwater. The seawater intrusion is available in the near-shore area. The mathematical model fairly predicted the relations between the decline of water-level and ground subsidence.

time (month, day)

FIG. 11 Multilevel water head at Wenfons


ACKNOWLEDGMENTS The authors would like to express their gratitude to the MOEA (Ministry of Economic Affairs) for its financial support through the research. Thanks are also due to TWCB (Taiwan Water Conservancy Bureau) for its valuable suggestions.

REFERENCES

Biot, M. A. (1941) General theory of three-dimensional consolidation. J. Appl. Phys., 12, 155-164.

Chang, C. C. (June 1985) The investigation of ground subsidence at Chiatung and Fungliao in Pingtung County. M. S. thesis, Dept. of Geography, National Taiwan Normal University.

Chern, H. F. (1984) The raise and subsidence of Taiwan Island based on the data of bench markes measurements. Central Geological Survey. No. 3, 127-140.

Davis, G. H. (1987) Land subsidence and sea level rise on the Atlantic Coastal Plain of the United States. Environ. Geol. Water Sci.. 10, No. 2, 67-80.

Detournay, E. and J. C. Roegiers (April 1987) Poroelastic consolidations in in-situ stress determination, in "Forced Fluid Flow Through Strong Fractured Rock Mass", International Workshop held at the Centre de Formation de Garchy.

Energy & Resources Laboratories, ITRI (July 1988) Ground Subsidence Investigation, Final Report.

Ghaboussi J. and E. L. Wilson (1973) Flow of compressible fluid in porous elastic media. Int. J. Num. Meth. in Engng.. _5, 419-442,431.

Hsu, T. L. (1954) The topogrpahy of coastal mountain in East Taiwan and recent raising movement. Taiwan Provincial Geological Survey, No.7, 3-5.

Hsu, T. L. (1962) A study on the coastal geomorphology of Taiwan. Proc. Geol. Soc. China. No. 5, 29-45.

Hsu, T. L. (1980) The relations between the topography and the new structure of Taiwan. Geol. Soc. China, No. 23, 3-5.

Hsu, T.L. & M. S. Chai (1974) Coastal features of Northern Taiwan and their neotectoric significance. Proc. Geol. Soc. China» No. 17,123-130.

Konishi, K., A. Omura, and T. Kimura (1968) 234U - 230Th dating of some late Quaternary coralline limestones from Southern Taiwan. Geology and Palaeontology of Southeast Asia. _5_, 221-224.

Li, Y. H. (1976) Denudation of Taiwan Island since the Pliocene Epoch. Geology. 4,105-107.

Liao, J. S. and B. C. Haimson (Nov. 27-29, 1989) Stability of near-surface excavations in weak rock. Symposium on Underground Excavations in Soils and Rocks, Including Earth Pressure Theories, Buried Structures and Tunnels, Bangkok, Thailand, Sponsored by Asian Institute of Technology (AIT) and Southeast Asian Geotechnical Society (SEAGS).

Lin, Y. T. (April 1986) Information on land subsidence in Coastal Areas of Taiwan. Council of Agriculature, Executive Yuan, R.O.C., p. 6.

Peng, T. H., Y. H. Li and F. T. Wu (1977) Tectonic uplift rates of the Taiwan Island since the early Holocene. Mem. Geol. Soc. China, No. 2,57-69.

Poiand, J. F. (1984) Guidebook to studies of land subsidence due to groundwater withdrawal. United Nations Educational, Scientific and Cultural Organization, 8-10.

Rice, J. R. and M. P. Cleary (May 1976) Some basic stress diffusion solutions for fluid-saturated elastic porous media with compressible constituents. Review of Geophysics and Space Physics. 14. No. 2, 227-241.

Smith, I. M. (1982) Programming the finite element method with application to geomechanics. John Wiley & Sons, New York.

Taira, K. (1975) Holocence crustal movements in Taiwan as indicated by radiocarbon dating of morine fossils and driftwood. Tectonophysics, 28, T1-T5.


Taiwan Water Conservancy Bureau (June 1988) The monitoring of ground subsidence in Pingtung Coastal Area. Final Report.

Yang, W. C. (June 1987) The ground subsidence in Taiwan. The Symposium on Ground Subsidence in Taiwan (I), held in Taipei, Sponsored by Energy & Resources Laboratories, ITRI, p. 235.

Documents

Subsidence,, Mayy 1991) 1991) .. IAH IAHSS ~ Publ no. 200,1991.hydrologie.org/redbooks/a200/iahs_200_0081.pdf · 2015-01-16 · S. Liao et al. 82 Lili River, and Peishui River with