Laura Lens Conservation and Management

Manual

October, 2015

JIRCAS

MRD

ЕРА

MWSC

Laura lsland, Majuro Atoll

Summary

There аге appIOximately 30,000 islands scattel'ed tlнoughout the vast Pacific Ocean,

and about 1,000 of these аге inhabited Ьу humans, some of whicl1 ai·e atolls. Atolls aie

small, low, flat, naпow islands, with 11ighly wateI-peimeaЫe gIOund, theгeby pIOhiЬiting

the forrnation of Iiveis and lakes. On sucl1 islands, гainfall is an impo11ant souгce of wateг,

and gгoundwateг becomes an impoгtant wateг геsоuгсе in the dгу season.

Most atolls ai·e located in а ь·opical 01· subtIOpical zone and expeгience high annual

pгecipitation. Howevei-, the pгesence of El Nino can cause dIOughts оп atolls in the Pacific

гegion. Thei-e is also сопсеш that climate and meteoIOlogical cl1a11ges caused Ьу global

waтming may expand агеаs of dIOugl1t 01· cause them to shift, and sucl1 effects would Ье

detiimental to low-latitude atoJls, whicl1 depeпd оп pгecipitation апd g1·oundwateг fог

tl1eiг wate1· гesouгces. It is theгefшe becoming iпcieasingly difficнlt to secuгe wateг

1·esouгces on atolls.

The RернЫiс of tl1e Maishall Islands (RMI), situated in MicIOпesia iп Осеапiа, has

the afшemeпtioпed ргоЫеms inhereпt to atolls. Маjшо Atoll, the capital, is inhaЬited Ьу

appгoximately half tl1e cotшtгy's popнlatioп, and secшing wateг геsошсеs is an extгemely

impшtant cЬallenge fог the island. In 1998, Маjшо Atoll expeгienced а sel'ioнs dгought

wheп little rainfall was l'ecot"ded fог seveial moпths in the dгу season, whicl11'est1lted in

а cгitical wateг slюгtage.

Т11е fгeshwateг lens on Lаша Island is а vаlнаЫе sошсе of watel' fог the downtown

aiea about 50 km to tl1e east and also fш otl1er агеаs of Маjшо Atoll. Up-coning of the

lens lшs now осснпеd as а гesнlt of excessive pumping iп а dгought season. Маjшо Atoll

needs the technology to еnаЫе as much fгesh gгoundwateг as is гequiied to Ье pнmped

without causing up-coпing, еvеп iп а dгought.

Iп this Iespect, the Japan Iпteшational Reseaгcl1 CenteI foi- Agiicultuгal Scieпces

(JIRCAS) has been conductiпg the геsеагсh on the shape change of Lauгa leпs since 2007.

Tl1e Iepoгt pi-esented Ьеге outlines the геsеа�·сЬ output and the gгoundwateг obseгvation

method.

ТаЫе of Contents

Chapter 1 lntroduction

1-1 Purpose

1-2 Definition

1-3 Basic principles

Chapter 2 Surveys and tests needed to formulate а water

utilization policy applicaЫe to freshwater lenses

2-1 Groundwater observation

2-2 Geophysical exploration

---·--

-·-·--·-·-· ---

2-3 Pumping test

2-4 Weather observation

Chapter 3 Facilitation of appropriate and effective water

use/water quality conservation and management

3-1 Numerical simulation-----

3-2 Calculation method of а water pumping standard

3-3 Method to reduce water pumping intensity

Chapter 4 Conservation and management system for Laura Lens

Annex

Chapter 5 Maintenance and improvement of retention

and recharge function

5-1 Horizontal impermeaЫe layer

5-2 Vertical douЫe water pumping

5-3 Underground dam

Chapter 6 Promotion of coordination within atoll (downtown

and Laura lsland)

6-1 PuЫic relations and education activities

6-2 Holding seminars

11

1

1

1

1

3

3

7

9

10

11

11

13

14

15

16

16

16

17

19

19

20

6-3 lnterview survey-----·- -·-· ·-----------·---· --------

6-4 Briefing session for local residents

6-5 Joint investigation

----- ___ ..... -- -·---

Chapter 7 Use of consultant

7-1 Boring survey

7-1-1 Outline

7-1-2 Methods

-·----------·----

7-1-3 lnstallation of observation holes

7-1-4 Boring and in-situ test

Chapter 8 Promotion of science and technology

8-1 Development of а douЫe packer

8-2 Development of а solar desalination system

Chapter 9 Ensure international collaboration and promote

international cooperation

9-1 The Pacific lslands Leaders Meeting

9-2 The World Water Forum

Chapter 1 О Others

10-1 Papers

10-2 ExhiЬition

10-3 Participants list

10-4 Brochure

--- -

---

-------------·--------------

111

21

21

22

23

23

23

23

24

25

27

27

28

29

29

30

32

32

32

32

34

Figure list

Figure 2.1.1 Strainer depths and electrical conductivities at monitoring well sites No. 4 (up) and No. 5 (down)

(January 2008)

Figure 2.1.2 Contour map of the depths of the saltwater-freshwater boundary оп Laura lsland (January 2008)

Figure 2.1.3 Water head contour map of Laura lsland (April 201 О)

Figure 2.1.4 Groundwater surface map of Laura lsland (April 201 О)

Figure 2.2.1 Wenner electrode array

Figure 2.2.2 Cross-sectional view of the freshwater lens under the central part of Laura lsland (lshida et al., 201 О)

Figure 3.1.1 Spatial discretization model in Laura island

Figure 3.1.2 Cross Sectional View of Freshwater Lens in 1985 in the central parts of Laura lsland

Figure 3.2.1 Monthly rainfall and daily safe water-pumping volume

Figure 3.3.1 Saltwater-Freshwater boundary of the freshwater lens when water is pumped from two intake wells

Figure 3.3.2 The new groundwater-intake system for Laura lsland

Figure 4.1.1 Conservation and Management System for Laura Lens

Figure 5.1.1 Conceptual diagram of а horizontal impem,eaЫe layer adapted from Masuoka and Horikoshi

(2014), with revision

Figure 5.1.2 Conceptual diagram of vertical douЫe pumping

Figure 5.1.3 Conceptual diagram of а floating-type underground dam adapted from Masuoka et al. (201 О) with

revision

Figure 7.1.1 Structure of Observation Hole

Figure 8.1.1 Structure of а douЫe packer (units: mm)

ТаЫе list

ТаЫе 7.1.1 Pipe Size

ТаЫе 7.1.2 Stratum Organization

ТаЫе 7.1.3 Results of the Pem,eaЬility Test

Photo list

Photo 2.3.1 Pumping test perfom,ed at the time of high tide

Photo 2.4.1 Weather observation instruments placed in the field on Laura lsland

Photo 6.1.1 Article in the Marsha/1 lslands Journal

Photo 6.2.1 Seminar оп "Conservation and Management of Freshwater Lenses" on OctoЬer 26, 2012, at the

Marshall lslands Resort Hotel

Photo 6.3.1 Laura beach after the 2010 Chile earthquake (left: northem part, right: southern part)

Photo 6.4.1 А briefing session for residents of Laura lsland

Photo 6.5.1 А joint investigation of groundwater оп Laura lsland

Photo 7.1.1 Joint of PVC pipe (left) and Slit of PVC pipe (right)

Photo 8.1.1 Detection of water leakage from the douЫe packer

Photo 9.1.1 PALM (top, participants viewing the displays; bottom, а participant chats with an exhiЬitor)

Photo 9.2.1 JIRCAS booth at the 7th World Water Forum

Photo 9.2.2 A side event at the 7th World Water Forum

Photo 10.4.1 Brochure in 2014

lV

Abbreviations

DUD : Darrit-Uliga-Dalap

ЕРА : Environmental Protection Authority

MALGOV : Majuro Atoll Local Government

MIA

MRD

MWSC

PALM7

RMI

SPC

: Ministry of lnternal Affairs

: Ministry of Resources Development

: Majuro Water and Sewer Company

: The 7th Pacific lslands Leaders Meeting

: RepuЫic of the Marshall lslands

: Secretariat of the Pacific Community

V

Foreward

The Lаига Le11s Co11seгvatio11 a11cl llfa11ageme11t llfa11zzal was cleveloped

fi·oш а stнdy of the сште11t state of t.he fl'eshwate1· le11s 011 Lаш·а Isla11d,

Maju1·0 Atoll, Rep1.1Ыic of the Mai·shall Isla11ds. This 111a11ual desc1·ibes а

шethod f01· obse1·vi11g the shape of t.he нpco11i11g that has оссштеd i11 tl1e

f1·eshwate1· le11s; it also desc1·ibes tl1e 1·esults of obse1·vatio11s a11d the 1·esнlts

of а 1н1111ei·ical si111нlatio11 of the sнstai11aЫe нsе of wate1· fi·oш the le11s.

Tl1e 1·esults of the stнdy of the сште11t state of the f1·eshwate1· le11s have

Ьее11 pнЬlished eve1-y yeai· i11 а sешi11ю· l1eld i11 dow11tow11 Маjш·о. Seшi11ai·

pai·ticipa11ts ai·e i11fo1·шed аЬонt. the сште11t state of the f1·eshvvatei· le11s ашl

have developed а st1·011g i11tei·est i11 cha11ges i11 it.s· shape. I11 past seшi11ai·s,

lively qнestion and a11swe1· sessio11s llave Ьееп lleld, with tl1e pai·ticipatio11 of

tl1e Majнl'O Wate1· a11d Sewe1· Сошра11у. wl1icl1 is iп cllai·ge of wate1· 1·esoш·ces

clevelopшeпt, as well as 1·ep1"ese11tatives of SOPAC ашl the U11ivei·sity of

Hawaii, who саше to Маjш·о Atoll.

А sнstai11aЫe way to нsе tl1e f1·eshwate1· leпs is yet to Ье acЬieved. I Ьоре

t.hat tЬе solutioп p1·oposed on the basis of the 1·esнlts of the 11шne1·ical

siшнlat.ion will Ье iшple111e11tecl as soo11 as possiЫe.

I11 closing, 011 behalf of tl1e Rep1.1Ыic of the Mai·sllall Islands. I wo1.lld like to

thank JIRCAS fDl' developiпg tl1is 111а11наl.

Oct.obel' 2015

�� Mi11ist.1-y of Resoш·ces a11d Developшent

Vl

Acknowledgement

In 2007, the Japan International Research Center for Agricultural Sciences (JIRCAS)

implemented an Island Environment Conservation Project with a grant from the Ministry

of Agriculture, Forestry and Fisheries. Since then, the Center has been investigating the

dynamics of the freshwater lens on Laura Island, Majuro Atoll, in the Marshall Islands,

as one of the Project's topics. In this topic, studies and tests are conducted to investigate

the current state of the lens, and a numerical simulation is conducted to find a sustainable

way to use the water.

Populations on tropical islands rely on rainwater and groundwater; they therefore have

unstable water resources that are substantially affected in terms of both quality and

quantity by meteorological and other conditions. Freshwater lenses on tropical islands

play an important role in the stable supply of water resources. If the planned strategies

prove to be effective, the sustainable use of water is expected to be useful in ensuring the

supply of drinking water and stable agricultural production on tropical islands such as

Laura.

This manual was developed as a final product of thi s project. It describes the results of

a study of the current state of the freshwater lens. I hope that the manual will be useful in

activities aimed at achieving the sustainable use of water from the lens th.rough sharing

of the results.

In closing, on behalf of JIRCAS, I would like to thank those in Japan and the Republic

of the Marshall Islands who provided support in conducting the study of the freshwater

lens.

Vll

October 2015

Tsutomu Kobayashi

JIRCAS Project Leader

Chapter 1 Introduction

1-1 Purpose

To promote the technology related to the use of Laura lenses to maintain or recover healthy

freshwater lenses, and to contribute to the healthy economical and societa l development of the

Republ ic of the Marsha ll Is lands etc. and the sta ble improvement of the quality of life of its

citizens.

1-2 Definition

(1) Freshwater lens

A lens-shaped layer of fresh groundwater that fl oats above seawater when rainwater and

seawater are in balance in an atoll island etc.

(2) Use of freshwater lens

Pumping up freshwater lenses that exist as groundwater in the Laura Island as we ll as other

places and were fo rmed when rainwater reached lagoons and oceans by evaporation or penetration

(3) Healthy freshwater lens

Freshwater lens in a condition such that water use and water quality/quantity are maintained

appropriately based on a mount of rainfall.

(4) Freshwater lens conservation and management

Healthy fres hwater lenses are mainta ined and managed.

1-3 Basic principles

(1) Importance of use of freshwater lens

In v iew of the important ro les played by freshwater lenses in water use, such as nurturing

anima ls and plants of the Marshal l Is lands as well as contributing to the life of the citizens and

industrial activ iti es, efforts to maintain or recover the use of healthy freshwater lenses must be

act ively promoted .

(2) Freshwater lens as a public resource

In view of the fact that freshwater lenses are a precious public property in the Marshal l Is lands

and are a highly va lued public resource, it must be ensured that they are used appropriately and that

the c itizens can continue receiving the benefits of fres hwater lenses in the future.

(3) Considerations for use of healthy freshwater lens

When freshwater lenses a re used, it should be considered th at effects on water use are avo ided

or minimi zed and the use of hea lthy freshwater lenses is maintained.

(4) Integrated management of the Majuro Atoll

In view of the fact that events that occur during the process of use of freshwater lenses w i 11

affect subsequent processes, th e use of fre shwater lenses mu st be managed comprehensive ly a nd

1

integrally, not on ly in the Laura Island, but a lso downtown.

(5) International cooperation related to use of freshwater lens

In view of the fact that the maintenance or recovery of the use of healthy fre shwater lenses is a

common concern for the citizens of the Marshall Islands as well as for Japan and other related

countries, efforts to use freshwater lenses must be promoted through internationa l

cooperation/collaboration.

Photo 1.3.1 Final manual meeting

2

Chapter 2 Surveys and tests needed to formulate a water utilization policy

applicable to freshwater lenses

2-1 Groundwater observation

(1) Observation of electrical conductivity

Electrical conductiv ity is observed at stra iner depth in severa l of the moni toring we lls

constructed by the United States Geo logical Survey in 1998. On the basis of the e lectrical

conductiv ities observed at strainer depth in two of these we lls, the depth at whi ch the e lectri cal

conduct iv ity reaches 200 mS/ m is ca lcu lated by interpo lation and assumed to be the depth of th e

saltwater- freshwater boundary of the fres hwater lens. For example, Figure 2. 1. I shows the method

used to obta in the depth of the saltwater- freshwater boundary of the fres hwater lens on graphs

depicting the depth and e lectrica l conductiv ity at the two existing moni toring-well sites (No. 4 and

No. 5) . Figure 2.1 .2 is a conto ur map of the depth of the saltwate r-freshwater boundary of the

freshwater le ns on Laura Is land in January 2008. T he tota l storage vo lume of the freshwater lens at

thi s time was roughly 1,800,000 t.

New monitoring we lls were constructed on the same s ites as the existing monitoring wells. The

we lls are structured in s uch a way that the hydraul ic head and e lectrica l conductivity can be

observed at any depth . An electri cal conductivity meter is used to observe the vert ical d istr ibution

of the e lectrical conductiv ity. T he results of groundwater observations revealed only a sma ll change

in e lectrica l conductivity w ith increasing depth in the new mon ito ring we lls. Moreover, because the

time-w ise flu ctuations in conductivity were large, it was d ifficu lt to observe th e saltwater­

freshwater boundary in these wells.

In response, a double packer that blocks water by us ing two a ir tubes (on the upper and lower

parts of the equipment) was developed fo r the new moni toring we ll s. Insta llation of a double

packer can prevent sa ltwater intrusion from the lower part of the monitoring well. The depth of th e

sa ltwater intrusion can be ident ified by the changes in electrical conductiv ity observed a t different

depths in the we ll.

0. 0

'? -3.o I c 0 -~ -6.0 > ~ ~ .c -9 .0 +.J a. Q)

~ -12.0 Q) c ro ~ -15.0

-18.0 0

I I

,..., I

'

I ~

----1\ Depth of the saltwater-freshwater boundary Altitude -15.61 m

200 400 600 800 1,000 1, 200 1,400 1,600

EC (mS/ m)

3

0.0

1 -3.0 c: ·o "l;; -6 .0 > Q)

Q)

~ -9.0 ...... c. Q)

~-12.0 Q)

c: ro .::;-15.0 (/)

-18.0

Depth of the saltwater-freshwater boundary Altitude -5.65 m

0 200 400 600 800 1,000 1,200 1,400 1,600 EC(mS/ m)

Figure 2.1 .1 Strainer depths and electrical conductivities at monitoring well sites No. 4

(up) and No. 5 (down) (January 2008)

North latitude (degr ees)

7. 165 +

7.16

7.155 +

A'

7.15 +

o.9 7.14

0 · Monitoring well s i te 7.135 I O . + -- : m pornts +

171 .02 171 .025 171 .03 171.035 171.04 171.045 171.05

East

longitude(degrees)

Figure 2.1.2 Contour map of the depths of the saltwater-freshwater boundary on Laura

Island (January 2008)

4

(2) Observation of groundwater levels

Water heads are observed at strainer depth in the monitorin g well s constructed by the United

States Geo logical Survey in 1998. Groundwater fl ows from the monitoring wells with higher

hydrauli c heads to those w ith lower hydraulic heads. A hydraulic head contour map was created

from the results of hydraulic head observations at 10 existing monitoring wells on Laura Is land

(Figure 2 .1 .3). At depths (altitudes) between - 8 and - 10 m on the is land , higher hydra ulic heads

were observ.ed on th e center part of th e is land . Therefore, we can presume th at groundwater fl ows

from the center to the surrounding area of the island.

North latitude (in degrees)

7. 16

7.155

7.15

7. 145

7.14 Legend

•: Observation well

Con tour in terval : 0.1 m

7. 135 Depth (altitude): - 8 to - 10 m

171 .03 171.035 171 .04

East longitude (in degrees)

Figure 2.1.3 Water head contour map of Laura Island (April 2010)

The groundwater surface is observed in loca l wells in the freshwater lens. The level of the

water table indicates the thickness of the freshwater lens on the surface of the sea. The water tabl e

is a lso observed in the new monitoring wells. A low groundwater surface, w hich should be

consistent w it h the le ns boundary depth, was deform ed by pumpage in Laura Is land (Figure 2. 1.4 ).

5

North latitude (in degrees)

7.16

7. 155

7.15

7. 145

7.14 Legend

e: Residents we ll

7.135

Contour interval: 0.1 m

171 .03 171 .035 171 .04

East longitude (in degrees)

Figure 2.1.4 Groundwater surface map of Laura Island (April 2010)

6

2-2 Geophysical survey

Two types of geophysical survey are used : an e lectromagneti c and an e lectrica l survey. In the

case of the electromagnetic survey, the loop- loop method of the vert ica l dipole mode is used to

measure the apparent conductivity of the ground by assuming that the ground consists of three

layers. In the case of the electrical s urvey, the res istivity of the layered structure is measured by

using the Wen ner fo ur-po int method (Figure 2.2. 1 ). In this method, when the survey depth

increases, the distance between the electrodes also increases.

r------

.... Center

- - - , I ... :

- - - - - -,

... I

7/ ~_/

Figure 2.2. 1 Wenner electrode array

The depths of the saltwater- freshwater boundary of the fres hwater lens a re obtained from the

results of the electri cal conductivity measurements performed in the ex isting monitoring wells. By

making use of these measurement results in the geophys ical survey, the cross-sectional shape of the

central part of the freshwater lens can be obtained (Figure 2.2.2).

0 300m

• • • •

No.5 No.4

Freshwater lens

• • •

• 5

10

• 15 Figure 2.2.2 Cross-sectional view of the freshwater lens under the central part of Laura Island (Ishida et al. , 2010)

As a res ult of the geophysica l survey, the up-coning that was observed in 1998 was observed

7

again in 2009, showing that it is difficult for the freshwater lens to return to its original shape.

Photo 2.2.1 Electrical survey

8

2-3 Pumping test

Pumping tests that change the fl ow rate of pumping from a wel l to measure time variations in

the re lati onship between fl ow rate and water level are performed to obtain flow characteristic

parameters. When pumping tests are performed along the seashore, a range of temporary pumping

well s or monitoring wells a re created so that tidal fluctuations can be taken into consideration.

Whether or not the groundwater beneath the pumping test area is in an unconfined aquifer or a

confined aqu ifer is determined on the basis of a tectonic map. AquiferTest Pro software is used to

analyze the test results. If the grou ndwater is in an unconfin ed aqu ifer, the Bou lton method is used

to ana lyze time variat io ns in the water level.

T he observed data ( i.e. the re lati onship between water leve l a nd time and e lectrical

conductivity and time, as well as the water leve l corrected fo r tide level and time) are shown in

graphic form. The relationship between e lectrica l conductiv ity and the amount of water pumped is

checked to confirm that an up-coning is not occurring during the pumping test. The re lat ionship

between the distance from a pump ing well to a mo nitori ng well and the equilibr ium water level of

the monitoring well is a lso checked to confirm that the influence of the water pumping reaches

on ly to the area where the water- level monitoring we ll s are located .

The specific production rate, coefficient of permeability, and others are ca lcu lated from the

above process. The storage volume of the freshwater lens is ca lculated on the bas is of the vo lume

of the freshwater lens aqu ifer and the specific y ie ld .

Photo 2.3.1 Pumping test performed at the time of high tide

9

2-4 Weather observation

Weather observation instruments are placed in the fie ld on Laura Island to co llect and organize

weather observation data. The types of weather observati on data co llected in clude temperature,

humidity, and precipitation. These data are saved on a recording device at a fixed t ime interval, for

instance, precisely every hour. Roughly about four times a year, th ese data are downloaded on a

personal computer to plot the m into a graph . The observation instruments- espec ia lly those that

collect th e most important data of a ll , name ly the amount of rainfall- need to be dup licated to

prepare for malfunctions of the weather observation in struments . These instruments are placed in

clear ings at least 5 m from the nearest palm tree (Photo 2.4.1 ).

(Upper left) Outdoor weather observation sensor

(Upper right) Indoor weather information console

(Lower left) Rain gauge sensor

(Lower right) Data logger

Photo 2.4.1 Weather observation instruments placed in the field on Laura Island

10

Chapter 3 Promotion of adequate and effective use of water and preservation and

management of water quality

The freshwater lens is impo1iant common property of the people of Majuro Atoll and is thus

also highly public property. In li ght of this fact, efficient use of water and other efforts to ensure

adequate and effective water use need to be promoted. In addition , restrictions and other

appropriate measures need to be implemented on water uses that may affect the freshwater lens by,

for example, increasing or decreasing water volume or causing a deterioration in water quality.

For sustainable use of the freshwater lens on Laura Island as a freshwater resource, it must be

maintained , preserved, and passed down to the generations to come in a condition that is not only

safe and secure in terms of water vol ume and water quality but also stable. Saltvvater up-coning is

the target in efforts to preserve the freshwater lens: the objective of preservation is to prevent the

up-coning from reaching the shaft (see below); moreover, the sa ltwater-freshwater boundary is

watched to preserve the freshwater lens. Creation of a pumping standard and implementation of

water utilization methods such as distributed pumping (based on the pumping amount determined

by numerically simulated experiments as the amount that shou ld not cause up-con ing) are

recommended in this regard.

3.1 Numerical simulation

The SEA WAT model is used to perform the above-ment ioned numerica l simulations and to

develop a preservation and management method applicab le to the freshwater lens on Laura Island.

The water in the freshwater lens is pumped from a shaft, which in the SEA WAT model is described

as a drain. Boundary conditions, such as the non-flow boundary, groundwater recharge rate, water

pumping volume, and constant head boundary, can be assigned. An area 100 m deep, 1900 m long,

and 220 m wi9e and centered on the cross-section of the central part of Laura Island where up­

coning into the freshwater lens was observed was chosen as the calcu lation area and subjected to

spatial discretization (Figure 3. 1.1). The results of the pumping tests are used to decide on the flow

parameters of the strata. The flow parameters of the ocean are such that it has some flowabi lity.

Average precipitation is input to create a freshwater lens over seawater. The initial shape of this

freshwater lens is almost the same as that of the freshwater lens in 1985 (the last recorded shape of

the freshwater lens before the up-coning) as shown in Figure 3.1.2.

11

A z~

A' l,900m

Figure 3.1.1 Spatial discretization model in Laura island

Legend Freshwater lens I Moni tor ing well

0 300m

Black dash line shows the observati on result of Laura lens boundary in 1985 (Presley, 2005) , and

black so lid line the numeri ca l simulation resul t. Ve11ica l solid line di sp lays location and depth of

observation wel ls. Locati on of A-A' is almost same as the survey line of physical prospecting.

Figure 3.1.2 Cross Sectional View of Freshwater Lens in 1985 in the central parts of Laura

Island

12

3.2 Calculation method of a water pumping standard

To try to preserve the freshwater lens by targeting up-conin g, a numerical s imulati on is

performed to estimate the daily water-pumping volume (i. e. th e output), in contrast to the

groundwater recharge rate (the input), by parametrically changing the monthly prec ipitation and

daily water-pumping volume. A safe water-pumping volume is calculated in re lation to

prec ipitation and will be the base line fo r preservation of the freshwater lens. By using a linear

approx imation fo rmula, the safe water-pumping volu me based on a past average monthly

precip itation of 271 mm was ca lculated and the result of 168.1 m3/day was obta ined. The average

monthly daily water-pumping volume fo r 1998 was smaller than the safe pumping vo lume.

Therefore, Laura Is land was found to be in a cri tica l condi ti on in which an up-coning may occur in

the fres hwater lens if th e monthly preci pitation turns out to be even slightly lower than that in

normal years but the da ily water-pumping vo lume is not reduced accordingly. The average water­

pumping volume at th e time of water pumping in 1998 somewhat exceeded the safe water-pumping

vo lume. The linear approximation formula in Figure 3.2 .1 shows the safe baseline fo r pum ping

water from the freshwater lens. If the pumped vo lume is be low th e I ine, then the vo lume is on the

safe s ide; if it is higher than the line, the volume is on the danger s ide.

250

o, 200 c 'a. E 6._ M 150 .... E Q) -

1 ~ 100 Q) .2 4- 0

~ > 50 .?;, ·ro 0

0 0 50

y = 0.576x + 12 R2 = 0.9983 ...

------__ .. ------

· -------·-----Safe baseline for pumping water from the freshwater lens

100 150 200 250 300 Monthly rainfall (mm)

Figure 3.2.1 Monthly rainfall and daily safe water-pumping volume

13

350

B

3.3 Method to reduce the water pumping intensity

If one extra hypothetical water- intake well is constructed and the volume of water pumped

from that well is halved to lessen the water- intake rate, then the depth of the up-coning caused by

the pumping of water from that s ingle intake well is a lso reduced to about half the orig inal depth

(F igure 3.3.1 ).

Water-intake well No. 3 Hypothetical water-intake well

l=aa======- Om B'

Freshwater lens

5 Saltwater- freshwater boundary of the ~--------+----------l- freshwater lens when water is pumped from

a single well

10 ---..!11 + Saltwater- fres hwater boundary of the

freshwa te r lens when water is pumped from two wells

~-=-=_,,....~...____._~~~~~~~~~~__Jl- 15

Note: 8-8' is a transverse line that passes north and south through water-intake well No. 3.

Figure 3.3.1 Saltwater-freshwater boundary of the freshwater lens when water is pumped

from two intake wells

The results of the numerica l s imulation showed that, to preserve the freshwater lens, it is

important to increase the number of water-intake well s so as to be able to reduce the pumping

vo lume at each we ll . In li ght of this finding, the rev iva l of abandoned we lls or the creation of new

we ll s in places where two existing we lls are w idely spaced is recommended (F igure 3.3.2).

Ocean 7 \

-._

{\:;) 6 ----5 ._.__ 8 (Ne intake well)

0

4 (lntak ~

well that should be revived)

3 ........--

2 Lagoon ,..-)-

0 Legend

• Water- intake well (numbers are those assigned to the wells) Shaft

View of the freshwater lens from above in 1985

Figure 3.3.2 The new groundwater-intake system for Laura Island

14

Chapter 4 Conservation and Management System for Laura Lens

EPA, MWSC, MALGOV and MRD should intensely and comprehensively promote the policies

relating to the Laura Lens use in the Republic of the Marshall Islands.

• Agriculture· Energy policy

• Local coordination

~ • • • • • Land survey

• Groundwater quality

use

l------------------------------------------------------------~

Figure 4.1.1 Conservation and Management System for Laura Lens

15

Appendix

Chapter 5 Maintenance and improvement of retention and recharge functions

To maintain and improve groundwater storage and recharge functions in groundwater storage

areas such as freshwater lenses, JIRCAS takes measures to develop civil engineering structures

capable of recharging water resources, along with other necessary measures.

5-1 Horizontal impermeable layer

Installing a horizontal impermeable layer between an intake well and the saltwater-freshwater

boundary of the freshwater lens reduces vertical flow of the groundwater due to water pumping

from the intake well. This delays the occurrence of up-coning. However, despite the delayed up­

coning in the freshwater lens, water pumping creates horizontal flow of groundwater and

consequently the freshwater lens shrinks horizontally. This causes agricultural water and water for

human consumption taken from shallow wells near the intake well to be become salinized earlier

than the water in the intake well. As a result, a freshwater lens that was usable before installation of

the horizontal impermeable layer is likely to become unusable.

Intake well Ground level

Sea level

Seawater

::.··

boundaty=o/fr��h"".,ater lens. ,,''' '

Figure 5.1.1 Conceptual diagram of a horizontal impermeable layer adapted from

Masuoka and Horikoshi (2014), with revision

5-2 Vertical double water pumping

To further 111 itigate up-coning, vertical double water pumping was proposed by Wolthek (2013)

and Masuoka, Yamamoto, and Aoki (2010). In this method, both freshwater and saltwater are

simultaneously pumped, so that the saltwater-freshwater boundary of the freshwater lens is

expected to rise in a shape similar to that before pumping. However, because water pumping can be

achieved only under conditions of I atmosphere of pressure and up to about IO 111 deep, this

method is subject to depth restriction. Because the saltwater-freshwater boundary of the freshwater

16

lens on Laura Island is deeper than IO m, only the water above the boundary can be pumped. In

addition, on Laura ls land, which has no rivers, even if saltwater is pumped it has to be discharged

back into the sea through a pipeline. To cope with these problems, sizable saltwater drainage

facilities will be required. Furthermore, saltwater taken in from deep areas may form new

underground water flow paths. Consequently, vertical double pumping is not suitable for mitigating

up-coning in the freshwater lens on Laura Island.

Pumping well Ground level

Sea level

Seawater boundary of freshwater lens

Figure 5.1.2 Conceptual diagram of vertical double pumping

5-3 Underground dam

In terms of water income and expenditure on Laura Island, the volume of recharged

groundwater surpasses that of pumped water. Water-pumping from the intake well generates a

water surface gradient in a concentric pattern on the groundwater surface, thus creating lateral flow

of groundwater. Recharged precipitation water other than that close to the wells and the intake well

flows into the ocean without being used. If an underground dam were to be constructed for

efficient use of the groundwater, outflow of the freshwater into the ocean would be prevented. This

would likely thicken the freshwater lens and mitigate the up-coning. An underground dam usually

stores groundwater by blocking an underground valley that is composed of impermeable bedrock

and sits above sea level; the dam has a cut-off wall that holds back the groundwater that would

otherwise flow into the ocean. A borin"g survey has yet to confirm the presence of impermeable

bedrock on Laura Island. This geological structure is suitable for an underground dam called a

floating-type underground dam (Masuoka, Yamamoto, and Aoki: 20 I 0). Th is type of dam is thus a

water intake facility that increases the freshwater storage volume by placing the cut-off wall along

the plane boundary of the freshwater lens. lnstal ling a floating-type underground dam along with

an intake well on the coast enables underground freshwater to be pumped before it wastefully

flows into the ocean. To achieve the function of a floating-type underground dam or underground

freshwater storage, the freshwater lens on Laura Island needs to be encircled by a cut-off wal I.

However, the underground dam that would need to be constructed along the plane boundary of the

freshwater lens on Laura Island would be so sizeable that it would not be practicable. In addition,

17

an underground dam would prevent nitrate-nitrogen derived from piggeries, chemical fertilizers,

and sewage from flowing into the sea. Overall, on the one hand, an underground dam would be

expected to act as a mitigation measure for up-coning, whereas on the other hand efforts to

conserve the quality of water (excluding saltwater) are highly likely to be needed. Therefore, cost

and water quality management would be challenges for the application of an underground dam on

Laura Island.

Intake well

Saltwater-freshwater boundary of a

freshwater lens before construction

the cut-off wall of an underground

dam

Seawa�

Cut-off wall of underground dam

Figure 5.1.3 Conceptual diagram of a floating-type underground dam adapted from

Masuoka et al. (2010) with revision

18

Appendix

Chapter 6 Promotion of coordination within atoll (downtown and Laura Island)

With the aim of achieving comprehensive and integrated management within the atoll, JJRCAS

is developing a system to promote collaboration and cooperation. We are also taking the measures

needed to reflect local residents' opinions of management measures within the atoll.

6-1 Public relations and education activities

An article on the JJRCAS seminar on October 26, 2012 was published in the November 9, 2012

issue of the local weekly newspaper, the Marshall Islands Journal (photo 6.1.1 ).

18 FmL11, No, ember 9. 2(\J ! - TI"' M:mh.ill Mand> Journal

GIFT JOID-0:,.'

comprehensil'e repon 011 co11sen-atio11 and ma11agemc111 ofrl1e Laura

res/, warer lens was deliwu'l!d

Fnday by a combmano,1 of Japan and Marj/,al/ /sla11d1 officuili.

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UIQ'ar..-kNUc9D­ICllldtobtlJ�nhr:: c.t:tn :a \'O=ol. �t'..UI· °' ,. \mp Jt,N'N ol fw.li .... bUC,laDll!l,�o .......

o,.. me Jaa � JMn oluUllnldedth�-ff•rr­k.Udl:fl"OJtft,JDC.Uoll· cw wCIGlaJnll • nn �a,a,,.,-..d:IM .. n5Mlm o!tM WZ. m -�loC"Olltlm.»­co.�w, .... .-dpol­hmoe cn:waD ••• �,,. •)t..JVOAtoll..,odmn· ,.� '"&' k,w-C'OR ---!M)' �coNpr.=io•itf« �w.Jc��,-..-

•= M'l'SC WUtt :COCIIOI

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Aibewa:�IO�t k.upw�a:=,apow· cq,c:..-..xC;ar?1Cd011111:bdA"t Mn loKtd 10 U., com·

r Illegal hook�ups and' leaks a huge problem

n.�w�u.a: -"' .as 50 l"'l«'n d. M\\"SC1 fl:clb w»c c. � --wn:pt o( .aprr...ffDlbeml.l';f...k lha1 (oc,c.-d, --.-»in:�'1XD0:1.plulflll

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U

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per.tr chc w.11; cm,:ac,-d to 6it JIO�W. n,d d .--1d ukt.1�hC'='l')'stO.! lusc�tutDdi.toG• IIOI._ J1;t.1,U::.e tKbol� np��bclm:uc\e. q'I an no11 k"'°' 11p .. M J.Dlia�a:ilmt lllitby1;l1u"1:k\i'\a.M 1nS tHbt.d to die�-­OCII o!l..d u o,..,... o! was.n m� d.m.1 it.. .rv,o)oohlf1:dait'*a::s.is to01Ucr.o!frlt51.-.. IM aaJQ1 rrAn'llQ' � nanr c.a."ChM-. at l.a•a S...1 ..U.dt-..dor...=� Wlw:m.Wlh luq:,ol:1 -- IM ....cl b rMa,·o• �f:l!:lttlc*sb

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Photo 6.1.1 Article in the Marshall Islands Journal

19

n..,,, ... ht,n.lN•al ltnnrd.Cn.11r (IIRC.U) r.. A,,nl,.n xw-NJ ..... _ d..Le1n1111lltfr w.,r. ..... *"rt• ... i..,1 frMJl11IJ.CAS DirM•K•..,.. 04'i'-irntl�k

Should we make

our own H20? hi 14:lt:io:ato stu)'11.1

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\\'•p!o.1�co2,:..2'll!ld.­npwodm20IJ ud­J:t aw� !o: 1 p,,lat os tli, tKk111elosr· bt ,w Oau lb, wo:\ u do:.1 1 mo:tdt�td�of lb. d.ulJI W1ll b. PlCl\,d.,& IOIU.tlot$cu.4.�-.uh: �

6-2 Holding seminars

Every October for the past 6 years, JJRCAS has held seminars on "Conservation and

Management of Freshwater Lenses" in downtown Majuro Atoll. The aim of the seminars has been

to share the results of our research investigations with relevant project organizations. Several tens

of people participated in each seminar. They represented, from government organizations, the

Ministry of Resources Development (M RD), the Environmental Protection Authority (EPA), the

Water Task Force of the Republic of the Marshall Islands (RMI), the Majuro Atoll Local

Government (MALGOV), and Majuro Atoll Waste Company (MA WC); from educational

institutions, the College of the Marshall Islands (CMI) and the University of Hawaii; and from

international organizations, the South Pacific Applied Geoscience Commission (SOPAC). Also

present were members of the Freshwater Lens Committee, consisting of representatives of

landowners in designated project areas; the manager of the Majuro Water and Sewer Company

(MWSC); the project coordinator of the MA WC; the Charged' Affaires ad interim of the Japanese

Embassy in the RMI; and representatives of the JICA/JOCV Marshall Islands Office.

After sessions on Q & A and the exchange of views at the seminar, a trainee from RMI who

had attended J ICA 's training course in Okinawa, titled "Conservation and Management of Water

Resources in Small Island Regions," reported on an action plan based on the training experience.

The participants commented, "Now we understand the importance of the conservation and

management of freshwater lenses. We want JIRCAS to continue its activities and proactively share

information about the current status of freshwater lenses."

Photo 6.2.1 Seminar on "Conservation and Management of Freshwater Lenses" on

October 26, 2012, at the Marshall Islands Resort Hotel

20

6-3 Interview Survey

J IRCAS assessed the impacts of the giant tsunami after the 20 IO Chi le earthquake on the

freshwater lens. We selected 18 private homes located near Laura Island's lagoon beach; on March

15 and 16, 2010, we interviewed the occupants and evaluated the quality of water from their wells.

Photo 6.3.1 Laura beach after the 201 O Chile earthquake (left: northern part, right:

southern part)

We interviewed occupants about changes in tide levels, flows, and well-water levels. The

results showed that the electrical conductivity of the well water was only about 120 mS/m at the

highest. The well water was therefore not salinated, suggesting that the tsunami had not affected

the freshwater lens. According to the interviewees, an ocean current had formed, running from the

beach at Laura Park on the northern part of Laura Island into the lagoon and raising the entire local

sea level. On northern Laura Island, erosion of coastal areas by the ocean current destroyed

concrete structures and tore up palm trees by their roots. In central and southern Laura Island,

garbage was strewn everywhere. The tsunami was estimated to have reached the height where the

damage occurred.

6-4 Briefing session for local residents

In April, 2014, JIRCAS held a briefing session for residents in the Laura district to explain the

current status of the freshwater lens. Participants included the Integrated Water Resources

Management (IWRM) team from SOP AC, as well as representatives of the EPA, MWSC, MRD,

and others. We explained the current status and problems of the freshwater lens to the residents by

using the results of the geophysical survey and of field investigations, such as observations of

underground water levels and quality that had been performed in collaboration with the EPA. At

21

the end of the session, we felt that we had won the understanding of the residents.

Photo 6.4.1 A briefing session for residents of Laura Island

6-5 Joint investigation

JIRCAS needs to form a cooperative system that will help to promote independent

development. Through simultaneous observations of water levels and quality, as well as water

quality analysis, all of which were performed in collaboration with EPA, we have implemented

human resource development programs for local young administrators.

Photo 6.5.1 A joint investigation of groundwater on Laura Island

22

Appendix

Chapter 7 Use of consultant

Necessary measures should be implemented to facilitate activities relating to the maintenance

and recovery of water cycle, which are conducted by technology consultant etc.

7-1 Boring survey

7-1-1 Outline

1) Objective

to install two observation holes to obtain basic information on the movement of the freshwater

lens in Laura, Majuro, Marshall Islands

2) Place

Laura, Majuro Atoll, the Republic of the Marshall Islands

3) Period

June 23 to July 5, 2009

4) Contents

• Boring :<p86mm Site No. 6: Excavation Length= 15 m Site No. I 0: Excavation Length= 16 m

• Pipeline: VP50 with strainer Site No.6: Length= 16 m Site No. I 0: Length= 17 111

• In-situ Permeability Test: Casing method: once in each hole

7-1-2 Methods

l ) Preparation

Boring scaffold, boring machine, and excavation machine tool are transported from Japan by ship

according to the ship schedule. Local site conditions are inspected before the works start.

2) Access and Safety Management

Getting access to the site etc. were conducted after the land owners approve the entering to their

lands at the land owners' meeting. Safety cones and a traffic control personnel were arranged to

make sure the pedestrian safety during the works.

3) Installation and removal of scaffold

Boring scaffold system was temporarily installed by single pipes. The minimum space, which was

necessary for the installation of the boring machine, was occupied and used. After the inspection

of the excavation depth was conducted by JIRCAS, the boring machine etc. were removed and

the working space was recovered as it was.

4) Boring (excavation works)

Oil-feed Boring Machine was used for the excavation. Non-core boring whose diameter of the

excavation was 86 mm was conducted. Not only a casing pipe was inserted but also the thickner

was used for the protection of the wal I of the excavated hole as the collapse of it was extremely

recognized.

23

5) Pipe works

After the excavation of the ground in 86111111 was finished, PVC pipe was installed in the hole.

Then, filtering materials were inserted between the pipe and the excavated soil wall. They are

compacted not only by shaking the pipe but also by adding water when they were inserted. The

height of the pipe from the ground is about 20 cm. The ground around the hole was covered by

mortar. To remove the slime and the mud cake attached inside the pipe, water cleaning was

conducted. After the cleaning was finished, the recovery of the permeability is expected.

6) In-situ Permeability Test

In-situ permeability test was conducted By using the casing through non-steady method at the

observation holes.

7-1-3 Installation of observation holes

I) Materials

PVC pipe, whose opening rate is I 0.8 %, was used for the strainer. The reason why

this pipe was used is that the pipe never uses the poisonous and artificial coloring

materials, which do not include zinc.

Photo 7 .1.1 Joint of PVC pipe (left) and Slit of PVC pipe (right)

Table? .1.1 Pipe Size

Nominal Diameter Outer Diameter Inner Diameter

50 mm 60 111111 51 111111

24

2) Schematic view of the structure of the observation hole

Height from the Head cap

ground: 20 cm

0

Tail cap

Ground surface

Waterproof treatment

(mortar)

Guard Pipeline

PVC pipe

Opening muon I 0.06%

Outer diameter 60mm

Inner diameter 51 mm

Filtering material

(gravel)

Figure 7.1.1 Structure of Observation Hole

7-1-4 Boring and in-situ test

I) Boring

The soil found in Laura is such a special one that the classification is not clearly established 111

Japan. However, according to JGS 0051-2000 established by the Japanese Geotechnical Society,

the stratum could be analyzed as follows.

25

2) Stratum Organization

Table 7.1.2 Stratum Organization

Site No. Thickness Stratum Main Characteristics

(m) Classification

From the ground surface to the depth of I. 7 meters, there are sands whose particles are uniformly-sized.

No.6 11.35 Sand stratum From I. 70 to the depth of I I .3 5 meters, water content ranges from small to medium, soils mainly consist of fine sands with small amount of angular gravels (diameter of about 2 to IO mm). Heavy water leakage and soil collapse

GL: can be observed. Distribution of the gravel stratum can be observed at the

l.83m depth than 11.35 meters. Sand and gravel with large water content whose diameter is about 50 to 60 111111

3.65 Gravel stratum (collapse ground) can be observed. Diameter of main gravel is about 2 to IO mm among which loose sand is 111 ixed with si It. Medi um-compacted as a whole but densely compacted below the depth of 15 meters. Buried soi I mixed with rubble can be observed from the ground surface to the depth of 1.1 Om. Fine sands with small to medium water content can be mainly observed

No.IO 9.7 Sand stratum from the depth of 1.10 111 to 6.60 m, in which wood roots are mixed. Loose and soft silty sands mixed with humic matter (mainly wood block) can be observed from the

GL: depth of 6.60 m to 9. 70 m. Bad and putrid smell can be recoimized

2.17m Th is stratum is distributed below the depth of 9. 7 m. Loose sand and gravel with large water content

6.3 Gravel stratum (collapsed ground) with coarse gravel whose diameter is about 50 to 60 mm. Diameter of main gravel is about 2 to IO mm. among which loose sand are mixed with silt.

3) In-situ Permeability Test

The result of the test shows that in terms of the permeability the soil property is classified into

medium category according to the permeability coefficient of 3.02E-05"-'8.57E-05 (m/s).

Table 7.1.3 Results of the Permeability Test

Number Depth (GL-m) Soil Property Permeability k (mis)

No.6 6.0 to 6.3 Sand with gravel 3.02E-05

No.JO 6.0 to 6.3 Sand with gravel 8.57E-05

26

Appendix

Chapter 8 Promotion of science and technology

To promote science and technology directed at restoring and maintaining the health of

freshwater lenses, JIRCAS improves its system of experimentation and research; promotes R & D

and disseminates the results; trains researchers; and takes any other measures needed.

8-1 Development of a double packer

To investigate the cause of increased electrical conductivity (EC) ef groundwater in monitoring

wells and to consider ways of combating it, EC in the monitoring wells must first be measured by

depth to identify the depth of saltwater intrusion. Tracers are generally used to detect the

groundwater flow layer. However, because the freshwater lens on Laura Island is a water supply

source, tracers cannot be used. We therefore considered alternatives to the use of tracers; as a

result, we produced a double packer in Japan and transported it into the field to apply to the

monitoring well on Laura Island.

A packer is an air-tube-integrated device that stops the vertical flow of groundwater in the

monitoring well. There are two types of packer, namely, single and double. A single packer is a

small device with one air tube, whereas a double packer is a large device with two air tubes.

The structure of the double packer is shown in Figure 8.1. To observe EC variations due to

groundwater intrusion from outside the monitoring well, an EC sensor is installed in the part where

the water is blocked by the air tubes. EC measurements taken by changing the depth of the double

packer al low us to identify the depth of saltwater intrusion and to estimate the condition of the

monitoring well when the well is partially blocked up to the monitoring depth.

Photo 8.1.1 Detection of water leakage from the double packer

27

Upper Part of Packer

\CD

Hanging ring

Air lube ¢6mm

Connection Pipe (sensor part)

Lower P a1t of Packer

Air lube ¢ 6mm

Rubber (inflation part)

Hole ¢6

Cone ¢ 38

Strainer ¢ 5X 10

Rubber (inflation pa rt)

Air tube c onnection (coupler+ s ockel)

Legend

Figure 8.1.1 Structure of a double packer (units: mm)

8-2 Development of a solar desalination system

Connection of each part

Connection with air lube

See the report on the development of a solar desalination system

(http://www.jircas.affrc.go.jp/engl ish/program/pdf/Development_ of_ solar_ desalination_ device_ en.

pdf).

28

Appendix

Chapter 9 Ensure international collaboration and promote international cooperation

Restoration and maintenance of the health of freshwater lenses are important issues in atoll

islands. From this perspective, JIRCAS ensures international collaboration in restoring and

maintaining healthy freshwater lenses; promotes technological cooperation on adequate and

efficient use of water; and promotes other types of international cooperation.

9-1 The Pacific Islands Leaders Meeting

The Pacific Islands Leaders Meeting (PALM) is held every 3 years in Japan. Leaders from 14

countries around the Pacific Ocean gather in Japan and, together with the Prime Minister of Japan,

discuss regional cooperation. The 7th PALM was held in the city of lwaki in Fukushima Prefecture

in May, 2015. JIRCAS participated in a side event, Pacific Festa 2015, which was held at the ARK

Karajan Plaza in ARK Hills in Tokyo. We exhibited posters, distributed brochures, played videos,

and exchanged views and information with participants.

29

Photo 9.1.1 PALM (top, participants viewing the displays; bottom, a participant chats with

an exhibitor)

9-2 The World Water Forum

JIRCAS participated in the 7th World Water Forum held in Korea in April, 2015. In the

Japanese pavilion, under the theme "Water for Food," we explained the activities of the project

"Environmental Conservation of Small Islands" to 949 participants from 72 countries and

organizations via both a slide presentation on a monitor and leaflet distribution. In a lecture at the

side event "Communal Water Management for Cohesive and Resilience," we presented a numerical

simulation showing that utilizing existing wells in such a way as to reduce water intake intensity

was an adequate method of freshwater lens conservation.

Photo 9.2.1 JIRCAS booth at the 7th World Water Forum

30

Photo 9.2.2 A side event at the 7th World Water Forum

31

Appendix

Chapter 10 Others

10-1 Papers

· Koda, K., Kobayashi, T., lshida,S., Yoshimoto, S. (2014.11) Numerical Simulation of freshwater

Lens in Laura Island, Geotechnical Engineering Magazine of the Japanese Geotechnical Society, Vo.62,

No.11/12, pp.30-33. (in Japanese)

• Koda, K., Kobayashi, T., Ishida, S., Yoshimoto, S., Kondou, Y., Kawamitsu, Y., and Ueno,

M.,(2013.10) Drought Impact on Freshwater Lens and the Countermeasures for Sustainable Irrigation,

I st Irrigation Forum, pp.63.

• Koda, K., Manpuku, Y., Kobayashi, T., Ishida, S., Yoshimoto, S., and Okubo, M.,(2013.7) A Study

of Sealing Effect in the Observation Well of the Freshwater Lens at Laura Island, Republic of the

Marshall Islands, JARQ, Yo.47, No.3, pp.257-272.

• Koda, K., Kobayashi, T., Ishida, S., Yoshimoto, S. (2013.7) Estimation of Hydraulic Parameters of

Freshwater Lens Aquifer in Laura Island, Water, Land and Environmental Engineering of the Japanese

Society of Irrigation, Drainage and Rural Engineering, Vol.81, No. 7, pp.541-545. (in Japanese)

• Ishida, S., Yoshimoto, S., Kobayashi, T., Koda, K., Nakazato, H. (2013.6) Application of

Geophysical Exploration for Investigation of Freshwater Lens in Small Island, Geotechnical

Engineering Magazine of the Japanese Geotechnical Society, Vo.61, No.6, pp.32-35. (in Japanese)

• Kobayashi, T., Koda, K.(2012.10) Development of Survey Method for Freshwater Lens in Marshall

Islands JIRCAS Working Repo1177

• Ishida, S.,, Yoshimoto, S., Kobayashi, T., Koda, K., Tsuchihara, T., Nakazato, H., Masumoto, T., and

Imaizumi, M. (2011.3) Measurement of freshwater-saltwater interface depths using geophysical

prospectings, Technical Report of the National Research Institute of Agricultural Engineering, No.21 I,

pp.9-20. (in Japanese)

10-2 Exhibition

Exhibition and presentation were conducted at the opportunities of Global Festa Japan (Tokyo),

Public Exhibition in Tsukuba, The 611, World Water Forum, The 6111 Pacific Islands Leaders Meeting, and

the I 51 World Irrigation Forum etc.

10-3 Participants list

This manual was completed in cooperation with the following participants.

[RMI]

Japanese Embassy

Hideyuki Mitsuoka, Kazuhiko Anzai, Akiyoshi Kashima, Hiroshi Watanabe, Masataka Mizutani

JICA Marshall Office

Hideki Tomobe, Jyunji Jshizuka, Hironobu Esaki, Tetsuji Nakasone

32

Ministry of Resources and Development

Thomas Kijiner, Rebecca Lorenij, Jabukja Aikne

Majuro Waste Company

Jorelik Tibon

Environmental Protection Authority

Lowell Alik, Debora Baker Manase, Abraham Hicking, Julius Lucky, Joann Komanta, Douglas, Paul

Paul, Rodorigo, Ayaka Kondou

Ministry of Internal Affairs

Representative

Majuro Atoll Local Government

Isaiah Ali

Majuro Water and Sewer Company

Joseph Batol, Alington Robert, Halston deBrum

College of Marshall Islands

Carl Hacker, Diane Miyazoe-deBrum, Runway Foster, Biuma Samson

Majuro Weather Service

Leee Jacklick

Marshall Islands Journal

Giff Johnson

[Others]

SPC (Fiji)

Peter Sinclair

USGS (Hawaii)

Stephen Gingerich and Marshall team

University of Hawaii

Glen Fukumoto

Schlumberger Co. Ltd. (Canada)

Miln Harvey

GIZ (Germany)

Walter Berier

[Japan]

Pacific Islands Center

Kazuyoshi Ogawa, Takehiro Kurosaki

Institute for Rural Engineering in Japan

Satoshi Ishida, Shuhei Yoshimoto, Katsushi Shirahata, Takeo Tsuchihara

Aoiteck Co.Ltd.

Masaaki Okubo

National Institute for Environmental Studies in Japan

Hiroya Yamano

JIRCAS

Masami Yasunaka, Kunihiro Doi, Nobuyoshi Fujiwara, Tsutomu Kobayashi, Kazuhisa Koda

( corresponding author)

33

Ministry of Resources and Development

Thomas Kijiner, Rebecca Lorenij, Jabukja Aikne

Majuro Waste Company

Jorelik Tibon

Environmental Protection Authority

Lowell Alik, Debora Baker Manase, Abraham Hicking, Julius Lucky, Joann Komanta, Douglas, Paul

Paul, Rodorigo, Ayaka Kondou

Ministry of Internal Affairs

Representative

Majuro Atoll Local Government

Isaiah Ali

Majuro Water and Sewer Company

Joseph Batol, Alington Robert, Halston deBrum, lseia Aiseia

College of Marshall Islands

Carl Hacker, Diane Miyazoe-deBrum, Runway Foster, Biuma Samson

Majuro Weather Service

Leee Jacklick

Marshall Islands Journal

Giff Johnson

[Others]

SPC (Fiji)

Peter Sinclair

USGS (Hawaii)

Stephen Gingerich and Marshall team

University of Hawaii

Glen Fukumoto

Schlumberger Co. Ltd. (Canada)

Miln Harvey

GIZ (Germany)

Walter Berier

[Japan]

Pacific Islands Center

Kazuyoshi Ogawa, Takehiro Kurosaki

Institute for Rural Engineering in Japan

Satoshi Ishida, Shuhei Yoshimoto, Katsushi Shirahata, Takeo Tsuchihara

Aoiteck Co.Ltd.

Masaaki Okubo

National Institute for Environmental Studies in Japan

Hiroya Yamano

JIRCAS

Masami Yasunaka, Kunihiro Doi, Nobuyoshi Fujiwara, Tsutomu Kobayashi, Kazuhisa Koda

( corresponding author)

33

10-4 Brochures

Project brochures, which describe the outline of research output, have been published in both

Japanese and English since 2011.

Development of Groundwoter Q11111/ty M•nagement Method .-.--.. �--- .............

.... ...ii.;......, ...... ,....,,,..,..__.,. - ---...-... ............ ,,, .... -�--· .......................... ...-.. ---..-.. ... _......._ .... ...,_..,..., ......... .,,. ----.. -.-.,1-...... .,_.... ... f) ......_,.,.,...,._. •.• -� . ., ... �-.11

....... -...... ...._ ..... ......,_,.. ................. ., ............. _.,.......

r Verlflutlon Test of Fermont•Uon-noor Plgp,,n ...._ ..... ,,..... .. �...._ ...... ...,.... .... .._ .. ,....._. ___ ............. .... .._.. ..... _IIQ9'., _____ ..... ,.,_......,..........,...,...._._ ................ ..,.._._ ............ ..-............ i.,_.,._............. ___ .,�_ .. _ ... _.,...

rF:::=-�-......

_..,... ........................ ,.. ___ ........ """ ................. _....... _ ... ....._ ................. _,. ... .... .___., ... ,,__ .... IIWI> .. ....... ....... ,, .. _......,___,.......,. -..... ....,._,, ... ...,.,. ................... _,,._.....,.,..,. ___ __.MICAI .. .._.. .. _...,. ..... __ ......... ._ .... ..,_�.

-..:::=.:�·----..___.,_ �.=::::.,.. ___ .. ,.. ____ .. __ _.,. •. _. __

IFo-rrJ ,,.. _____ __..,., __ .,----·--·-·-.,---.. � -------------.""' ...._Ji ______ _...,._..,. --..---�·-..... -_ .. ______ ... ...., .. --_ _...._._.,. ............ _ -::--.. ::·::::.=:i:::--.... -0..,11- ...... ---. -· -

.. .,. .. ______ .....,. ....... _., .... _..__.-....,. ... _...... _______ .. ----....-....... -_ .. ______ ... ___ _ ..-.-�-... --... -· :::..-=. :-..:::, :...-:::.::-::.: -...--... --.. --.. -. ....... �------..-·-_ _........,, _____ .. ___ ... --.--...... ----..---" ... "_"' ..._,,,.__,..._ ... _.__ ·--

_..,. ___ .,.. __ c-..,.,.,.._.._�--.. _ ,, ... ....,_,,, .. ___ ... _ ____ .. ___ ..,_.._ ·---,,,.-....-........ --

l'- ___ ,,, ___ .... _

0-- .. --........ --..-- .....-..iw _______ _ ·--·----... -·- _ ... _·-·----·---.-_,, ____ .,.. __--.....-----..-...-...... ._ .. ___ __,,,.,. _______ ....,,, __.,._,,,_,,, ... __ .. __ _

==--=--=-==-== __ .. _,_ .. _...., __ _. __ .. ,,.._

.. :.:::--=.-:.:=:Q.. ____ ____ -�--.... ·...:.

_ ... -

..::::::=

r WMt are Fre•-.r Lenses? '-"-'"" .. _ ...................... .._.. .... _ ....... _ ..................... ............. ..._ ........... -.....-.................... -.-.... ......-.... .... --·---.....;,.------- ... _,. .. ,...... ......... __ _ ... _____ ..,,,._...._.._ .................................. ._. .... _.._ ........ ., ...... __ ._ ....... .,_ ................ .,,. ..... ...._. .. c:....- .......... .,._, ..... ..,,,,_...._ �� .......... �,, .......... ...... ---·--... -.... ....... ----... ----""--

Photo 10.4.1 Brochure in 2014

¢

Japw, lnt..-nfflOnal R...arch Cent.,

fOf Agricultural Sdenc:89

...... �C:---"'"iKCT-. 1-l,°""""""l'WillM. ...............

----

•

r Fragile Freshw.ier I.ens ........... ...._..,, ... _......., ..... �--�--......... __ _ ...... -_,.. .... _.,,_.......,_ ........ ....._ ... __ ,..... ......... -.......... ----.1• ...... - ......... ....._. ....... __ ..._,.,_ --- .... -- .. %111� ........... -... ..._.._ ............... _,_� .. Conservation StandorrJ of the Frrntrwator Lons ........ """"'"'._ .......... _.,.,_....., ,..... ________ .......

_--,._.,.._ ...... IIM'llll,I' ....... ...... _.., ..... _ ... _,,,.,..__.,.._ ... _......... ___.._ ._......,._r.--_ .." ..... ..._ .... ___,..,.,......_ ....._..,....,....__.........,.. ...... _..,_ ..._...,,�_,. .. ....._. ... .........._....., ............. _,,....,_,....... ... _....._....,..,,,,_.._. ....

34