soil salinity in aceh after the december 2004 indian ocean tsunami

8/9/2019 Soil Salinity in Aceh After the December 2004 Indian Ocean Tsunami

1/9

Soil salinity in Aceh after the December 2004 Indian Ocean tsunami

M.K. McLeod a,*, P.G.Slavich a, Y. Irhas b, N. Moore a, A. Rachman c, N. Ali b, T. Iskandar b,C. Hunt a, C. Caniago b

a Industry & Investment NSW Primary Industries Australia, Tamworth Agricultural Institute, 4 Marsden Park Road, Tamworth, Calala, N.S.W. 2340, AustraliabAssessment Institute for Agricultural Technology, Aceh, Indonesiac Indonesian Soil Research Institute, Bogor, Indonesia

1. Introduction

The earthquakemeasuring more than 9.0 on the Richter scale on

26 December 2004 triggered a violent, 10 m high tsunami, killing

and injuring hundreds and thousands of people and affecting farm

lands in low-lying coastal areas around the Indian Ocean.

The effect of this tsunami on agriculture includes soil

salinisation (Subagyono et al., 2005; Rachman et al., 2005;

Wijewardena and Gunaratne, 2005; Chaudhary et al., 2006;

Rengalakshmi et al., 2007; Chandrasekharan et al., 2008; Raja

et al., 2009), soil sodicity (Rachman et al., 2005), increased soil

organic matter content (Rengalakshmi et al., 2007; Agus et al.,

2008), heavy metal contamination (Szczucinski et al., 2006;

Swamy et al., 2006; Ranjan et al., 2008), increased Na, K, Ca, Mg,

Cl, and SO4 contents (Szczucinski et al., 2006), increased soil pH,

cation exchange capacity, N, P, and K contents (Chaudhary et al.,

2006; Rengalakshmi et al., 2007); deposition of various types and

origin of sediments (FAO, 2005a; Paris et al., 2007; Tarunamulia,

2008; Slavich et al., 2008; Rachman et al., 2005; Bahlburg and

Weiss, 2007; Szczucinski et al., 2006; Chaudhary et al., 2006;

Rengalakshmi et al., 2007; Babu et al., 2007), changes in surface

topography and hydrology associated with soil erosion and

sedimentation (Slavich et al., 2008; Bahlburg and Weiss, 2007;

Szczucinski et al., 2006), and soil physical degradation (Hulugalle

et al., 2009). The effect on agriculture water included poor

irrigation water quality associated with increased turbidity and

decreased oxygen level (Chaudhary et al., 2006), increased water

salinity (Wijewardena and Gunaratne, 2005; Rengalakshmi et al.,

Agricultural Water Management 97 (2010) 605613

A R T I C L E I N F O

Article history:Received 1 June 2009

Accepted 27 October 2009

Available online 19 January 2010

Keywords:

EM38

Seawater inundation

Soil electrical conductivity

Leaching

Electromagnetic induction

A B S T R A C T

The 2004 Indian Ocean tsunami inundated about 37,500 ha of coastal farmland in Aceh, and cropsplanted after the tsunami were severely affected by soil salinity. This paper describes the changes of soil

salinity over time on tsunami affected farms and the implications for resuming crop production after

natural disasters.

Soil salinity and salt leaching processes were assessed across the tsunami affected region by

measuring soil apparent electrical conductivity (ECa) using an electromagnetic induction soil

conductivity instrument (EM38) combined with limited soil analysis. The ECa was measured 5 times

between August 2005 and December 2007 in both the vertical (EMv) and horizontal (EMh) dipole

orientations at 23 sites across Aceh. The level of salinity and direction of saltmovementwere assessedby

comparing changes in mean profile ECa and relative changes in EMv and EMh.

Eight months after the tsunamithe average soil salinity in the 01.2 m soildepthvariedfrom ECe22.6

to 1.6 dS m1 across sites in the affected region and three years after the tsunami it varied from 13.0 to

1.4 dS m1. Soil salinity tended to be higher in rice paddy areas that trapped saline tsunami sediments

andheld seawaterfor longerperiods.Leaching of salts occurred slowly by both vertical displacement and

horizontal movement in surface waters. Hence, soil salinity persisted at a level which could reduce crop

production for several years after the 2004 tsunami. High soil salinity persisted three years after the

tsunami even though there had been more than 30007000 mm of accumulated rainfall to leach salts.The slow leaching is likely to have been due to the loss of functional drainage systems and general low

relief of the affected areas.

Monitoring of soil salinity with EM38 assisted local agricultural extension agencies to identify sites

that were too saline for crops and determine when they were suitable for cropping again. The

methodology used in this study could be used after similar disasters where coastal agriculture areas

become inundated by seawater from storm surges or future tsunamis.

Crown Copyright 2009 Published by Elsevier B.V. All rights reserved.

* Corresponding author. Tel.: +61 2 6763 1457; fax: +61 2 6763 1222.

E-mail address: [email protected] (M.K. McLeod).

Contents lists available atScienceDirect

Agricultural Water Management

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / a g w a t

0378-3774/$ see front matter. Crown Copyright 2009 Published by Elsevier B.V. All rights reserved.

doi:10.1016/j.agwat.2009.10.014
mailto:[email protected]://www.sciencedirect.com/science/journal/03783774http://dx.doi.org/10.1016/j.agwat.2009.10.014http://dx.doi.org/10.1016/j.agwat.2009.10.014http://www.sciencedirect.com/science/journal/03783774mailto:[email protected]


2/9

2007; Raja et al., 2009; Szczucinski et al., 2006), increased levels of

As, Mn, Fe, and B (Ploethner, 2006), and contamination with

bacteria and coliform (Swamy et al., 2006).

Most previous studies on soil salinity in tsunami affected areas

are limited to few locations and did not attempt to quantify

changes in profile soil salinity on a regional scale over a period of

years.Raja et al. (2009) reported soil salinity status of up to two

rainy seasons after the tsunami, but sampling was limited to the

upper 0.3 m of the soil profile. Szczucinski et al. (2007)repeated

measurement 1 year after the tsunami, but focussed only on the

surface sediment layers.

Acehslowland farmingsystemtypically consists of ricegrownin

rotation withpalawija crops. Riceis the maincropgrownduring the

wet season (SeptemberJanuary), and palawija such as peanut,

soybean, mungbean and maize as a cash crop grown in the dry

season (Adisarwanto et al., 2001). In areas with a reliable irrigation

water supply, two or three crops of rice are grown per year.

The tsunami in 2004 damaged about 37,500 ha of farmlands

along Acehs coastline, including fishponds, rice fields, plantations,

horticulture, home gardens and open fields. The damage was more

severe and extensive on the west coast due to its closer proximity

to the epicentre of the earthquake (FAO, 2005a). The area of

damaged rice fields is about 30,000 ha, with an estimated loss of

production of at least 120,000 t of rice per planting season. Therehabilitationof the tsunami affected landwas necessary to restore

food security in the rural areas and the livelihood of local farmers.

After the tsunami, aid organisations donated tools, seeds and

fertilisers to Acehs farmers, and those on the east coast were able

to replant their least damaged fields within five weeks of the

tsunami. However, many reported subsequent crop failure. There

was a need to monitor the changes in soil salinity from season to

season to guide farmers when land was again capable of producing

food crops.

Soil salinity level can be assessed by measuring the electrical

conductivity (EC) of the soil. Soil EC can be measured by either

laboratory or field methods. Laboratory methods typicallymeasure

the ECof a soilwaterextractfrom a mix of1 partof soil and 5 parts

of deionised water (EC1:5) or the ECof a saturated soil paste extract(ECe). Soil ECe relates more closely to the soluble salt concentra-

tion of the soil solutionand hence is more related to plant response

across soils of different texture than EC1:5, which is a measure of

total soluble salts per gram of soil. This is why ECe is usually used

to classify soils into low, medium, and high levels of soil salinity.

The apparent electrical conductivity (ECa) is a field based measure

of bulk electrical conductivity of the undisturbed soil profile. ECa

can be measured using the electromagnetic induction method. ECe

can be estimated from EC1:5 by using an appropriate conversion

factor related to soil texture (Slavich and Petterson, 1993) or from

ECa using a site-specific calibration equation (Slavich and

Petterson, 1990; Rhoades et al., 1999).

Field instruments for measuring the apparent electrical

conductivity of soils using electromagnetic induction (EM) havebeen widely used to assess soil salinity (Bennett and George, 1995;

Triantafilis et al., 2000; Bennettet al., 2000), land suitability forrice

(Beecher et al., 2002), soil sodicity (Nelson et al., 2002), soil acidity

(Dunn and Beecher, 2007); spatial variation of soil moisture (Huth

and Poulton, 2007), soil texture (Hedley et al., 2004), and depth to

clay pan (Sudduth and Kitchen, 1993; Sudduth et al., 1995; Jung

et al., 2006).

Ground-based EM instruments such as the EM38 (Geonics Pty

Ltd) can provide a rapid measure of the ECa of a soil profile to a

maximum depth of 1.5 m. The main advantage of EM38 is its

portability, allowing rapid salinity assessment of relatively large

and scattered areas. If the exact locations of measurement are

recorded,the survey can be repeated over time to assess changes in

soil salinity levels.

The sensitivity of the EM38 response to soil ECa varies with soil

depth. Measurements in the horizontal mode (EMh) have greatest

sensitivity to soil ECa at thesoil surface and decliningsensitivity to

a depth of 0.35 m;while measurements in the vertical mode (EMv)

are more sensitive to soil ECa at 0.35 m depth and declining in

sensitivity to a depth of 1.5 m (Slavich and Petterson, 1990). The

relative value between EMh and EMv can be used to estimate the

distribution of soil salinity in the soil profile. If the value of EMh is

greater than EMv, salt levels are likely to be greatest in the top 0

0.35 m of the soil profile. When EMv is higher than EMh then salt

levels are likely to be greatest below the 0.35 m depth. This

difference in sensitivity can be used to assess salt leaching

processes.

In this study soil salinity changes over time in the tsunami

affected areas across the Aceh province, were monitored to guide

farmers as to when land was suitable for resuming crop

production. The different sensitivities of horizontal and vertical

dipole readings from the EM38 were utilised to provide an

indication of salt leaching processes.

2. Methods

2.1. Site and soil descriptions

Twenty-three monitoring sites within 5 km of the east coast of

Aceh Province were selected across Aceh Besar, Banda Aceh, Pidie,

and Bireuen districts (Table 1; Fig. 1), depending on the availability

of replanted crops in the tsunami affected fields, road access, and

the security of personnel. The study was commenced before the

Aceh peace agreement was signed and only secure areas with

established local agricultural extension networks were selected.

Most of the assessment sites were bunded lowland irrigated and

rainfed rice fields (sawah), and some were more elevated and used

to grow vegetables orpalawija crops.

In each site, 13 fixed transects of up to 100 m each were

selected based on visual assessment of crop performance (poor,

medium, and good) during the initial survey in August 2005. There

were a total of 38 transects across the 23 sites. The number of siteswas reduced to 22 in January 2007 because site 4 was converted

into housing. In December 2007, only 10 sites where high salinity

levels remained were measured.

InAugust 2005, soils fromsites 1,4, 5,6, 8,16 and 22(coveringa

range of ECa values) were sampled at increments of 0.1 and 0.2 m,

down to 1.2 m for chemical analyses.

Rainfall distribution in the study area is bi-modal (Fig. 2). The

wetseason is from Septemberto January andthe dryseason is from

February to August. The long term average of annual rainfall for

Aceh Besar, Pidie, and Bireuen districts is 1668, 1889 and

1613 mm, respectively. The cumulative rainfall from 2005 to

2007 for these districts is 5205, 7779 and 7214 mm, respectively.

Entisol is the dominant soil type in the coastal floodplain of

Aceh (Rachman et al., 2005). All the assessment sites containedalluvial floodplain soils with silty loam to silty clay at 00.2 m

depth (Table 1). The puddling practices in lowland rice fields in

Aceh create a medium to heavy clay pan layer at about 0.2 m to

hold water during the rice growing season. Below the clay pan

layer soil texture ranges from loamy sand to clay.

2.2. Assessment tools and procedures

Agricultural research and extension staff in Aceh were trained

in salinity assessment using soil sampling and the EM38

instrument. The soil ECa was measured in both the horizontal

(EMh) and the vertical (EMv) dipole orientations, at about 5 m

intervals along each transect. The instrument was placed on the

groundif the soil was dry and 3 cmabove the groundif the soil was

M.K. McLeod et al./ Agricultural Water Management 97 (2010) 605613606


3/9

saturated. Each site was measured fivetimes between August 2005

and December 2007.

Information collected from farmers during the initial EM38

survey included: the approximate depth and duration of sea water

inundation, thickness of sediment and its treatments (removed or

incorporated), farming practices and management before and after

tsunami (i.e. crop types, sequence, yield, crop and fertiliser

management).

2.3. Soil analyses

Profilesoilsamples fromsites 1,4, 5,6, 8,16 and 22(collected in

August 2005) were analysed for EC, soluble salts, and chloride

contents (in 1:5 soil/water extract), exchangeable Na+ in Ammo-

nium Acetate 1 M, pH 7 extract (Rayment and Higginson, 1992),

and particle size analysis with the pipette method.

2.4. Assessment of repeatability of the transect methodology for the

EM38 instrument and the correlation between ECa and ECe

The repeatability of the EM38 transect methodology on a

particular day was determined to provide an estimate of the error

for comparing data collected at different times after the tsunami.

Two sites, one relatively dry and one wet, were used for this

assessment in May 2006. The wet soil transect (near site 20) had 7points of measurement. The dry soil transect (near site 21) had 10

points of measurement. Each transect was measured 5 times, and

transect mean and its standard error were calculated for both EMh

and EMv in the dry and wet soils.

Four steps were used to establish the correlation between ECa

and ECe. First, the EC1:5 data from each soil depth layer was

converted to ECe for each soil depth based on texture class

followingSlavich and Petterson (1993). The factor of 8.6 (for soils

with 3045% clay content on weight basis) was used as this

represents the dominant soil in Acehs lowland agriculture areas. A

similar conversion factor was also recommended by FAO for rice

paddy soil inAceh (FAO, 2005b). Second, the average ECe value was

calculated forthe soil profile. Third, the average soil profileECa was

calculated using (EMh + EMv)/2 following Slavich (2002). Finally, a

linear regression was fitted between the average profile ECe and

ECa.

Thesalinitylevel in each assessment site wasclassed into lowto

medium (ECe 8 dS m1), after converting ECa to ECe.

2.5. Conceptual model of salt leaching based on changes in EMh and

EMv over time

It was assumed that shortly after the tsunami event, the soil

salinity of the affected areas would have been highest near thesurface soil. This assumption was based on three factors. First, the

tsunami came after the wet season had started and the soils were

likelyto have been close to saturation. Second, most soilsin the area

had been used for paddy rice production and commonly contain a

densehardpan as a result of annual puddling. Both thesefactors are

likely to have limited the intake of salt water into the lower part of

thesoil profileafter thetsunami.Third,salt would havebeenpresent

in the deposited sediment that remained on the soil surface.

Soluble salts can move from surface soil via either horizontal or

vertical leaching processes. Horizontal leaching refers to salt

movement into surface water flowing across the soil. This water

carries salt laterally to lower areas where it may accumulate or be

removed in a drainage system. Lateral movement is likely to occur

during filling of rice paddies and in floods, both of which occurredin Aceh after the tsunami. Vertical leaching refers to displacement

of salt by water draining vertically through the root zone to subsoil

layers. Changes in EMh andEMv values of transects over time were

used to infer at which sites leaching of surface salts had occurred

and in which direction.

The vertical leaching of salt would be expected to lead to a

decrease in surface soil salinity (decrease in EMh values) and a

corresponding increase in subsoil salinity (increase in EMv values),

and lower average profile ECa. Hence EM38 data may be able to

identify the 3 stages of vertical leaching illustrated inFig. 3. This

assumes that there is potential for vertical drainage and that no

further salinisation occurs at the soil surface.

During lateral movement of salts from the surface soil by

floodwaters, subsoil salinity would be expected to change very

Table 1

Location and description of assessment sites.

Site ID Village/sub district/ district Latitudec N Longitudec E Landuse system Soil texturea ( 0 20 cm) C rop- Aug 0 5

1 Seukeu/Simpang Tiga/Pidie 05821.5060 095858.4980 Palawija-rainfed Silty clay Tomato

2 Seukeu/Simpang Tiga/Pidie 05821.5220 095858.4880 Palawija-rainfed Silty clay Cauliflower

3 Tungoe/Simpang Tiga/Pidie 05820.1690 096800.4020 Palawija-rainfed Silty clay Onion

4 Raya/Triang Gadeng/Pidie 05815.4450 096811.0470 Palawija-rainfed Clay loam Peanut

5 Cot Lheu Rheng/Simpang Tiga/Pidie 05815.0990 096812.9700 Sawah-rainfed Clay loam Rice-all dead

6 Cot Lheu Rheng/Simpang Tiga/Pidie 05815.2210 096814.9910 Sawah-rainfed Clay loam Rice

7 Meuraksa/Meureudu/Pidie 058

15.4190

0968

14.7620

Sawah-rainfed Silty clay loam Rice8 Reudeup/Panteraja/Pidie 05815.7890 0968009.8010 Palawija-rainfed clay loam Bare

9 Kuala Jeumpa/Jeumpa/Bireuen 05812.7450 096839.7450 Sawah-irrigated Silty clay loam Rice

10 Bateh Timoh/Jeumpa/Bireuen 05813.1800 096840.2520 Sawah-irrigated Silty clay loam Rice

11 Cot Geureundong/Jeumpa/Bireuen 05813.5180 096840.0 701 Sawah-irrigated Silty clay loam Rice

12 Lapang Timu/Gandapura/Bireuen 05814.2940 096854.0600 Sawah-rainfed Silty clay Fallow

13 Jangka Alueu/Jangka/Bireuen 05815.2170 096847.4070 Sawah-irrigated Silty clay Rice

14 Teupin Keupula/Jeunib/Bireuen 05811.1530 096830.4330 Sawah-irrigatedb Clay loam Rice

15 Meulik/Samalanga/Bireuen 05811.9780 096822.4670 Sawah-irrigated Silty loam Rice

16 Nusa/Lhoknga/Aceh Besar 05829.4950 095816.1010 Palawija-rainfed Silty loam Water melon

1 7 Miruk Taman/Darussalam/Ace h Besar 05835.3600 095823.7860 Sawah-rainfed Clay loam Rice

18 Suleue/Darussalam/Aceh Besar 05834.9160 095823.1400 Sawah-rainfed Loam Rice

1 9 Bl ang Krueng/Baitussal am/Aceh Besar 05835.2020 095822.5330 Sawah-rainfed Silty clay Rice

2 0 Lampeudaya/Baitussa lam/Aceh Besar 05835.5010 095823.2840 Sawah-rainfed Loamy sand Rice

21 Lampineung/Kuta Alam/Banda Aceh 05833.6340 095820.6910 Palawija-rainfed Silty clay loam Egg plant

2 2 BP TP Ground/La mpine ung/Banda Aceh 05833.6730 095820.7300 Palawija-rainfed Silty clay loam Onion

2 3 BP TP Ground/La mpine ung/Banda Aceh 05833.6730 095820.7300 Palawija-rainfed Silty clay loam Bare

a

Based on particle size analysis data (McDonald and Isbell, 2009).b Non-reliable irrigation water supply.c Latitude and longitude coordinates are in WGS84 datum.

M.K. McLeod et al./ Agricultural Water Management 97 (2010) 605613 607


4/9

Fig. 1. Location of the assessment sites within the Aceh Besar district (top), Bireuen district (middle), and Pidie district (bottom).



5/9

little. Therefore, under this process EMh readings would be

expected to decrease, EMv would either not change or decrease

slightly, so that the average ECa would decrease.

3. Results

3.1. Soil chemical properties and correlation with ECa

The EC1:5, chloride, soluble salt and sodium contents of the

tsunami affected soils from sites 1, 4, 5, 6, 8, 17 and 22 were highly

correlated, supporting the assumption that the EC1:5measured in

these soils was mainly related to salinity induced by seawater

inundation. These correlations are described by the following

equations:

Cl 1475EC1:5 166 r2 0:96;P


6/9

weeks. This excludes areas that were totally lost to the sea.

However, the association between the period of inundation and the

salinity level between sites was surprisingly weak (Fig. 6) because

by August 2005 some farmers had already removed the tsunami

sediment out of their fields whereas others incorporated it into the

soil during the cultivation. In addition, some sediment and salts

would have been distributed during the rainy period as was foundin Thailand (Szczucinski et al., 2007).

The length of inundation tended to affect the depth of sediment

deposit in paddy fields, but not inpalawijafields (Fig. 6), probably

because of the fact that the bunded paddy field could trap water

longer, allowing more time for deposition of suspended sediment.

Soil salinity was affected by irrigation water management after

the tsunami, as illustrated inFig. 7. Sites 5 and 6 are two adjacent

rice fields with no drainage infrastructure (closed field). In site 6

the tsunami water was pumped out of the field after the tsunami,

while in site 5 it remained in the field. A significant difference in

salinity levels was measured in October 2005 (Fig. 7). Rice crops in

site 5 with extreme salinity level all died, while in site 6 the

vegetative growth of the rice crop was good. This highlighted the

importance of maintaining water circulation through the rice field

where fresh water was available to enable rice establishment after

the tsunami.

Spot soil and water EC measurements, visual observation, and

verbal records from farmers during the survey confirm that soil in

the irrigated rice fields in most districts were less saline than those

in the rainfed rice fields. In dryland rice fields near site 12 the firstrice seedlings after the tsunami, transplanted in February 2006,

died due to high water salinity in the rice bay (ECwater of 8

10 dS m1). In contrast, thesecond rice crop (after tsunami, August

2005) in theirrigated field near site 3, didnot show any evidence of

salinity effects. Water in the irrigation channels and rice bay was

fresh (EC of 0.30.7 dS m1).

3.4. Changes in soil salinity over time

Between January and July 2005, 500759 mm rain fell across

the Bireuen, Pidie, and Aceh Besar districts. This rain is likely to

have removed some salt but was not sufficient to bring all sites

back to a low salinity level. In August 2005, 6 sites were classed as

Fig. 7. Comparison of salinity levels between two adjacent rice field bays with

different water management in October 2005.

Fig. 6.The relationship between the: (a) period of inundation and depth of sediment, (b) period of inundation and the EMh, and (c) depth of sediment and EMh.

Fig. 5. Salinity levelsincreased witha longerperiod of seawater inundationafter the

tsunami in a rice bay in Keuneue village, near site 15, Lho Nga, Aceh Besar.



7/9

low to medium, 11 as high, and 6 as very high salinity (Fig. 8a). The

number of sites with high level salinity hadreduced to 6 by January

2007 and 4 by December 2007, while the number of sites with lowto medium level salinity increased to 9 by January 2007 and 12 by

December 2007.

The conceptual leaching model based on the relative changes in

EMh and EMv values suggested that there was relatively little

change in the leaching status of sites between August 2005 and

May 2006 and larger changes were more evident after January

2007 (Fig. 8b). In August 2005, 15 of the 23 sites had EMv > EMh

and were classed as havingbeen subject to some degreeof leaching

(Fig. 8b). This increased to 17 sites only by January 2007 and 21

sites by December 2007.

Of the 8 sites that were at stage 1 leaching in August 2005

(Fig. 8b), 4 sites still had high surface salinity in January 2006.

However, by December 2007, surface salts had been leached from

all of these sites. There were also 5 sites (including 3 sites in thePidie district) that were already leached in August 2005 but the

surface salinity increased in January 2006 before progressively

being leached again (Fig. 8c). There was 600 mm of rainfall

between September and December 2005 in the Bireuen district,

and 1565 mm in the Pidie district, causing severe flooding in

December 2005. It is possible that these rains and flood waters

redistributed salts to the lower part of the landscape, so that the

salinity of some sites increased, while some decreased. By the end

of 2007 most of these sites were leached, except site 19 that was

surrounded by a housing development blocking the drainage

outlet.Total rainfall in Aceh Besar,Pidie and Bireuen in 2006 was 1557,

2354, and 4095 mm respectively. The totals for 2007 were 2172,

2633, and1976 mm respectively. Althoughthe soil salinity at most

sites was less byJanuary2007, 13of the sites still had a highto very

high soil salinity level (Fig. 8a) despite the high rainfall. By

December 2007, the number of sites with high level salinity

reduced while sites with low-medium level salinity increased. The

number of sites with very high level salinity remained almost

unchanged from August 2005 to December 2007. These are sites

without irrigation and drainage infrastructure (the rainfed sawah

at sites 5, 6, 7, 12, 19 or sites surrounded by housing development

such as site 23). These sites share the common problem of

inadequate drainage infrastructure.

The relative changes in EMv and EMh (Fig. 9) suggest that saltappears to have moved in both horizontal and vertical directions.

In the rainfedpalawijasite 21 in Aceh Besar (Fig. 9a) the EMh was

slightly greater than EMv in August 2005. However, by January

2006, EMh had decreased and EMv had increased, which suggests

that there was vertical leaching of salts from the surface soil to an

intermediate depth in the profile (stage 2 leaching,Fig. 3b). In the

rainfedsawah site 7 (Fig. 9b), there was a large increase in EMh

associated with a much smaller increase in EMv in May 2006. This

Fig. 8. Salinity status (a), leaching stages (b) and sites with fluctuating salinity (c) from August 2005 to December 2007.

Fig. 9. Changes in EMh and EMv over time in sites with different land use systems.



8/9

suggests horizontal redistribution of salts. The EMh and EMv then

decreased steadily from May 2006 to the end of 2007, possibly due

to a combination of vertical and horizontal leaching processes. The

657 mm of rain that fell in Aceh Besar from September to

December 2005, might have contributed to the surface redistribu-

tion of salts on this site.

4. Discussion

Monitoring with the EM38 instrument showed that soil salinity

level was highly variable across the tsunami affected landscape. A

wide range of soil salinity level (low to very high) is also found in

other studies from areas affected by the 2004 tsunami (Subagyono

et al., 2005; Rachman et al., 2005; Wijewardena and Gunaratne,

2005; Chaudhary et al., 2006; Rengalakshmi et al., 2007;

Chandrasekharan et al., 2008; Raja et al., 2009).

The soil salinity during the cropping seasons after the tsunami

was likely to be affected by a complex of factors which included

depth of original tsunami sediment deposited, time of inundation

with seawater immediately after the tsunami, cumulative rainfall,

the occurrence of floods, access to drainage systems and the way

farmers managed surface water. Whether farmers removed

tsunami deposits from their fields is also likely to have affected

the soil salinity level after the tsunami.The EM38 methodology assisted rapid identification of the

impact of most of these component factors. It also indicated that

both lateral movement of salt across the floodplain and vertical

leaching were significant processes leading to lower soil salinity.

Only a few instances of changes from stage 1 to stage 2 profile

salinity distribution were observed from the time series EM38

data. The changes in EM38 data more commonly indicated the

profile salinity changed between a stage 1 and stage 3 distribution.

This could result if stage 2 occurred at times between EM38

surveys and was not captured by the methodology and/or if the

leaching processes in these landscapes are characterised mainly by

lateral flows or by-pass flows in the vertical direction.

The highly variable soil salinity and salt removal processes

meant that agricultural extension agencies needed to gather site-specific information when advising farmers of the potential for

their farms to grow crops after the tsunami. Extension officers in

Aceh were equipped with twoEM38 instruments to advise farmers

of soil salinity during the recovery period.

The degree of damage to drains and irrigation systems, and the

management of soil andwaterafterthe tsunami influenced thesoil

salinity levels. The tsunami caused blocked drains and damaged

irrigation channels, so seawater entering the bunded lowland rice

fields during the tsunami was not able to run out of the fields

immediately after theevent. This mayhave increased the time that

seawater covered thesoil after thetsunamicompared with some of

the more elevated palawija fields. However, without proper

drainage, even the palawija fields could be highly saline as

demonstrated in sites 21 and 22. Both these sites are located in thelow-lying area of Banda Aceh that was covered by up to 15 cm of

extremely saline sediment.

Rice farming practices in Indonesia require an impermeable

clay pan at about 20 cm depth to hold water during the growing

season. These clay pans are likely to have reduced the depth of

infiltration of seawater and limited the rate of vertical leaching.

The reduction of soil salinity levels in these rice fields is likely to

have been by salt movement into standing water followed by

lateral/surface drainage.Evidence of this was observed by poor rice

yields in the lowest parts of rice fields.

It is possible to grow successful paddy rice crops in saline soil

provided that there is adequate circulation of fresh water through

the rice field (MacDonald and Beale, 1995),andEC ofwaterin bays

is maintained below 2.5 dS m

1

(Beecher, 1991). These findings

were supported by field observations made on successful rice crops

during the survey.

In Aceh, leaching of salts from the soil surface in the Pidie

district was reported as early as March 2005 (Subagyono et al.,

2005) and most of the assessment sites in this study had already

started leaching by August 2005. However, in most areas the soil

salinity level was still too high for most local crops. Soil salinity

decreased slowly to a low level over 23 years after the tsunami in

sites with operating irrigation and drainage infrastructure.

However, some rainfed rice fields, areas affected by tidal

movement, and areas without adequate drainage infrastructure

remained saline at the end of 2007.

This study indicates that the removal of salts from rice bays in

these areas should be conducted through horizontal flushing

rather than vertical leaching. Horizontal flushing, either with

natural rainfall or irrigation, can only be done if the surface

drainage network is operational. Therefore, providing a good

drainage infrastructure should precede efforts in soil rehabilitation

in tsunami or cyclone affected agricultural land. Palawija crops

were grown in raised beds to provide better in field surface

drainage. The beds assist removal of mobilised salts from surface

soil to the district drainage channels.

Natural disasters require rapid response to enable survivors to

resume their livelihoods and food production as soon as possible.Whilst tsunami disasters of this scale are rare, smaller tsunamis

and storm surge that inundate coastal areas with seawater are not

uncommon. It should be expected that farmers affected by similar

sea water inundation events will need rapid site-specific assess-

ments of soil salinity before making cropping decisions. Aid

agencies also need to be aware that soil salinity changes can be

very slow and need to adjust their disaster assistance programs to

account for this. This study has shown that electromagnetic

induction technology can be deployed rapidly by local trained

personnel within disaster areas to assist recovery phase decisions

related to seawater induced soil salinity and subsequent monitor-

ing.

5. Conclusions

Soil salinity in Aceh after the tsunami was highly variable. Soil

salinity tended to be higher in rice paddy areas that trapped

tsunami sediments and held seawater for longer periods. Lowland

rice paddy fields tended to be more saline than the more elevated,

coarser and drier palawija fields.

The salinity persisted at a level that could reduce crop

production for several years even though there had been several

hundred millimetres of rainfall to leach salts. Leaching of salts

occurred slowly by both vertical displacement and horizontal

movement in floodwaters. The slow leaching is likely to have been

due to the loss of functional drainage systems and due to

compacted hard pans beneath rice fields.

Soil salinity assessment using the EM38instrument has allowedrapid soil salinity identification and monitoring of tsunami

affected land over large distances across Aceh without the need

for ongoing soil sampling and chemical analysis. The variability in

initial salinity caused by the tsunami and in leaching rates meant

that farmers needed site-specific assessments of soil salinity to

inform them when their land was suitable for cropping.

Acknowledgements

This project was funded by the Australian Centre for

International Agricultural Research (ACIAR). This project was

supported by local Dinas Pertanian (District Agriculture Services),

PPL (Field Extension Officer) network in various districts of Aceh,

and BPTP NAD staff. We are grateful to Brian Dunn, Geoff Beecher,



9/9

Rebecca Lines-Kelly, and Ross McLeod of Industry & Investment

NSW Primary Industries for their constructive comments on the

earlier draft of this paper.

References

Adisarwanto, T., Kuntyastuti, H., Taufik, A., 2001. Legumes in tropical rice-basedcropping systems in Indonesia: constraints and opportunities. In: Gowda,C.L.L., Ramakrishna, A., Rupela, O.P., Wani, S.P. (Eds.), Legumes in Rice Based

Cropping Systems in Tropical Asia: Constraints and Opportunities. Interna-tional Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patan-cheru, India, pp. 2641.

Agus, F., Subagjo, H., Rachman, H., Subiksa, I.G.M., 2008. Properties of tsunami-affected soils and the management implication. Paper presented at 2nd Inter-national Salinity Forum, 31 March3 April, Adelaide, SA. Accessed March 2009fromhttp://www.internationalsalinityforum.org/Final%20Papers/agus_B2.pdf.

Babu, N., Babu, D.S.S., Das, P.N.M., 2007. Impact of tsunami on texture and miner-alogy of major placerdeposit in southwest coast of India. Environ.Geol. 52, 7180.

Bahlburg, H., Weiss, R., 2007. Sedimentology of the December 26, 2004, Sumatratsunami deposits in eastern India (Tamil Nadu) and Kenya. Int. J. Earth Sci. 96,11951209.

Beecher, H.G., 1991. Effect of saline water on rice yields and soil properties and theMurrumbidgee Valley. Aust. J. Exp. Agric. 31, 819823.

Beecher, H.G.,Hume, I.H.,Dunn, B.W., 2002. Improved method for assessing rice soilsuitability to restrict recharge. Aust. J. Exp. Agric. 42, 297307.

Bennett,D.L.,George, R.J.,1995. Usingthe EM38to measure theeffect of soil salinityon Eucalyptusglobulusin south-westernAustralia. Agric.Water Manag.27, 69

85.Bennett, D.L., George, R.J., Whitfield, B., 2000. The use of ground EM systems to

accurately assess salt store and help define land management options forsalinity management. Explor. Geophys. 31, 249254.

Chandrasekharan, H., Sarangi, A., Nagarajan, M., Singh, V.P., Rao, D.U.M., Stalin, P.,Natarajan, K., Chandrasekaran, B., Anbazhagan, S., 2008. Variability of soil-water quality due to Tsunami-2004 in the coastal belt of Nagapattinam district,Tamil Nadu. J. Environ. Manag. 89, 6372.

Chaudhary, D.R., Ghosh, A., Patolia, J.S., 2006. Characterisation of soils in thetsunami affected areas of Tamilnadu for agronomic rehabilitation. Curr. Sci.91 (1), 99104.

Dunn, B.W., Beecher, H.G., 2007. Using electro-magnetic induction technology toidentify sampling sites for soil acidity assessment and to determine spatialvariability of soil acidity in rice fields. Aust. J. Exp. Agric. 47, 208214.

FAO,2005a. Special Report: FAO/WFP Food supply and demand assessment forAcehProvince and Nias Island (Indonesia). Accessed 26 February 2009 fromhttp://www.fao.org/docrep/fao/008/j5202e/j5202e00.pdf.

FAO, 2005b. FAO Field Guide: 20 things to know about the impact of salt water onagricultural land in Aceh Province. United Nations Food and Agriculture Organi-

zation. Accessed May 2005from www.fao.org/ag/tsunami/docs/saltwater-guide.pdf.

Hedley, C.B., Yule, I.J., Eastwood, C.R., Shepherd, T.G., Arnold, G., 2004. Rapididentification of soil textural and management zones using electromagneticinduction sensing of soils. Aust. J. Soil Res. 42, 389400.

Hulugalle, N.R., Jaya, R., Luther, G.C., Ferizal, M., Daud, S., Yatiman, Irhas, Yufniati,Z.A., Feriyanti, F., Tamrin, Han, B., 2009. Physical properties of tsunami-affected soils in Aceh, Indonesia: 2 1/2 years after the tsunami. Catena 77(3), 224231.

Huth, N.I., Poulton,P.L., 2007. An electromagnetic induction method for monitoringvariation in soil moisture in agroforestry systems. Aust. J. Soil Res. 45, 6372.

Jung, W.K., Kitchen, N.R., Sudduth, K.A., Anderson, S.H., 2006. Spatial characteristicsof claypan soil properties in an agricultural field. Soil Sci. Soc. Am. J. 70 (4),13871397.

MacDonald, F., Beale, P., 1995. Management of rice using saline bore irrigationwater. IREC Farmers Newsletter. Australia, 145, 46.

McDonald,R.C., Isbell, R.F.,2009.Soil profile. In:TheNational Committeeon Soil andTerrain (Eds.),Australian Soil and Land Survey Field Handbook. third ed. CSIRO

Publishing, Melbourne, pp. 147204.Nelson, P.N.,Lawer,A.T., Ham, G.J.,2002.Evaluation ofmethodsfor field diagnosisofsodicity in soil and irrigation water in the sugarcane growing districts ofQueensland, Australia. Aust. J. Soil Res. 40, 12491265.

Paris, R., Lavigne, F., Wassmer, P., Sartohadi, J., 2007. Coastal sedimentation associ-ated with the December 26, 2004 tsunami in Lhok Nga, west Banda Aceh(Sumatra, Indonesia). Mar. Geol. 238, 93106.

Ploethner,D., 2006. Groundwater quality along the tsunami affected coast betweenBireuen and Sigli in the province Nanggroe Aceh Darussalam, Northern Suma-tra, Indonesia, 2006. Tech. Reportvol. C 1 of Project: Managementof Georisks inNAD, Technical Cooperation Project No. 2005.2083.3: BGR Hannover, Germany.

Rachman, A., Wahyunto, Agus, F., 2005. Integrated management forsustainable useof tsunami-affected land in Indonesia. Paper presented at the Mid-term Work-shop on Sustainable Use of Problem Soils in Rainfed Agriculture. Khon Khaen,Thailand, 1418 April 2005. Accessed November 2007 fromhttp://www.cgiar.org/tsunami/publications/files/useoftsunami-affectedland.pdf.

Raja, R., Chaudhuri, S.G., Ravisankar, N., Swarnam, T.P., Jayakumar, V., Srivastava,R.C., 2009. Salinity status of tsunami-affected soil and water resources of South

Andaman, India. Curr. Sci. 96 (1), 152155.Ranjan, R.K.,Ramanathan, A., Singh, G., Chidambaram, S., 2008. Assessment of metalenrichment in tsunamigenic sediments of Pichavaram mangroves, southeastcoast of India. Environ. Monitor. Assess. 147, 389411.

Rayment, G.E., Higginson, F.R., 1992. Australian Soil and Land Survey Handbook:Australian Laboratory Handbook of Soil and Water Chemical Methods. InkataPress, Melbourne-Sydney.

Rengalakshmi, R., Senthilkumar, R., Selvarasu, T., Thamizoli, P., 2007. Reclamationand status of tsunami damaged soil in Nagappattinam District, Tamil Nadu.Curr. Sci. 92 (9), 12211223.

Rhoades, J.D., Chanduvi, F., Lesch, S., 1999. Soil salinity assessment: methods andinterpretation of electrical conductivity measurements. FAO Irrigation andDrainage Paper No. 57. FAO, Rome.

Slavich, P.G., Petterson, G.H., 1990. Estimating average root zone salinity fromelectromagnetic induction (EM-38) measurements. Aust. J. Soil Res. 28 (3),453463.

Slavich, P.G., Petterson, G.H., 1993. Estimating the electrical conductivity of satu-rated paste extracts from 1:5 soil:water suspensions and texture. Aust. J. SoilRes. 31, 7381.

Slavich, P., 2002. Ground based electromagnetic induction measures of soil electri-cal conductivity. Applications and models to assist interpretation. In: Beecher,H.G. (Ed.), Electromagnetic Techniques for Agricultural Resource Management.Proceedings of a Conference, July35, 2001,Yanco Agricultural Institute,Yanco,NSW. Australian Society of Soil Science Inc., Riverinas Branch, pp. 17.

Slavich, P., McLeod, M., Moore, N., Tinning, G., Lines-Kelly, R., Iskandar, T.,Rachman, A., Agus, F., Yufdy, P., 2008. Tsunami impacts on farming in Acehand Nias, Indonesia. Paper Presented at 2nd International Salinity Forum,31 March3 April. Adelaide, SA. Accessed March 2009 fromhttp://www.internationalsalinityforum.org/Final%20Papers/slavich_B2.pdf.

Subagyono, K., Sugiharto, B., Jaya, B., 2005. Rehabilitation strategies of the tsunamiaffected agricultural areas in Nanggroe Aceh Darussalam, Indonesia. In: Salt-affected Soils from Sea Water Intrusion: Strategies for Rehabilitation andManagement Regional Workshop, 31 March1 April 2005. Bangkok, ThailandAccessed November 2007 from http://www.cgiar.org/tsunami/publications/files/rehabilitationstrategies.pdf.

Sudduth, K.A., Kitchen, N.R., 1993. Electromagnetic induction sensing of claypandepth: ASAE Paper No. 931550. American Society of Agricultural Engineers. St.

Joseph, MI.

Sudduth, K.A., Kitchen, N.R., Hughes, D.F., Drummond, S.T., 1995. Electromagneticinduction sensing as an indicator of productivity on claypan soils. In: Robert,P.C., Rust, R.H., Larson, W.E. (Eds.), Proceedings of the Second InternationalConference of Site Specific Management for Agricultural Systems. ASA, CSSA,and SSSA, Madison, WI, pp. 671681.

Swamy, Y.V., Chaudhury, G.R., Das, S.N., Sengupta, S., Muduli, R., 2006. Assessmentof water quality in tsunami affected Andhra coast. Curr. Sci. 91, 14091412.

Szczucinski, W., Chaimanee, N., Niedzielski, P., Rachlewicz, G., Saisuttichai, D.,Tepsuwan, T., Lorenc, S., Siepak, J., 2006. Environmental and geological impactsof the26 December 2004 tsunami in coastalzone of Thailand-overviewof shortand long-term effects. Polish J. Environ. Stud. 15 (5), 793810.

Szczucinski, W., Niedzielski, P., Kozak, L., Frankowski, M., Ziola, A., Lorenc, S., 2007.Effect of rainy season on mobilisation of contaminants from tsunami depositleft in coastal zone of Thailand by the 26 December 2004 tsunami. Environ.Geol. 53, 253264.

Tarunamulia., 2008. Application of fuzzy logic, GIS and remote sensing to theassessment of environmental factors for extensive brackish water aquaculturein Indonesia. Masterof ScienceThesis.Facultyof Science. TheUniversityof New

South Wales, Sydney, Australia (unpublished).Triantafilis, J., Laslett, G.M., McBratney, A.B., 2000. Calibrating an electromagneticinduction instrument to measure salinity in soil under irrigated cotton. Soil Sci.Soc. Am. J. 64, 10091017.

Wijewardena, J.D.H., Gunaratne, S., 2005. Impact of Tsunami on Soil and WaterResourcesA Case Study in the Matara District, 7. Ann. Sri Lanka Dept. Agric.,Peradeniya, Sri Lanka, p. 403.

http://www.internationalsalinityforum.org/Final%20Papers/agus_B2.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/agus_B2.pdfhttp://www.fao.org/docrep/fao/008/j5202e/j5202e00.pdfhttp://www.fao.org/docrep/fao/008/j5202e/j5202e00.pdfhttp://www.fao.org/ag/tsunami/docs/saltwater-guide.pdfhttp://www.fao.org/ag/tsunami/docs/saltwater-guide.pdfhttp://www.cgiar.org/tsunami/publications/files/useoftsunami-affectedland.pdfhttp://www.cgiar.org/tsunami/publications/files/useoftsunami-affectedland.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/slavich_B2.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/slavich_B2.pdfhttp://www.cgiar.org/tsunami/publications/files/rehabilitationstrategies.pdfhttp://www.cgiar.org/tsunami/publications/files/rehabilitationstrategies.pdfhttp://www.cgiar.org/tsunami/publications/files/rehabilitationstrategies.pdfhttp://www.cgiar.org/tsunami/publications/files/rehabilitationstrategies.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/slavich_B2.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/slavich_B2.pdfhttp://www.cgiar.org/tsunami/publications/files/useoftsunami-affectedland.pdfhttp://www.cgiar.org/tsunami/publications/files/useoftsunami-affectedland.pdfhttp://www.fao.org/ag/tsunami/docs/saltwater-guide.pdfhttp://www.fao.org/ag/tsunami/docs/saltwater-guide.pdfhttp://www.fao.org/docrep/fao/008/j5202e/j5202e00.pdfhttp://www.fao.org/docrep/fao/008/j5202e/j5202e00.pdfhttp://www.internationalsalinityforum.org/Final%20Papers/agus_B2.pdf

soil salinity in aceh after the december 2004 indian ocean tsunami

Documents