| dc.description.abstract | On 26 Desember 2004 a strong earthquake in Aceh caused the tsunami
wave. The wave had a kinetic energy resulting from the water movements, the
characteristics of water as agent of leaching and dissolving, and mud containing
organic and inorganic matter carried by the wave, all of resulted in the change of
ecosystem in the major part of the coastal areas of Nangroe Aceh Darussalam,
including the change of soil characteristics. This research aims to study (1) the
characteristics of tsunami mud, (2) the characteristics of tsunami affected soil, (3)
to classify of soil in the tsunami-affected areas, and (4) guidance for management
of the tsunami-affected soil. In relation to the above research objectives, 17 soil profiles that were
affecteed or not by the tsunami mud were observed. A sample of the tsunami mud
materials were collected from the research location. The determination of the soil
profiles (pedons) was based on the distance from the beach, land use, and the
types of soil. The distance of soil profiles from the coastal line consists of less
than 500 metres from the coastal line, 1000-2500 metres from the coastal line, and
3000-5000 metres from the coastal line, The type of land use consist of rice fields,
ponds, gardens, and shrubs. observation in each profile focused on the
morphological, mineral, physical, chemical, and biological characteristics of soil.
The morphological characteristics of soil were observed on the cross section soil profile. Meanwhile the mineralogical, physical, chemical, and biological
characteristics were analyzed based on the soils samples collected from the
horizon of each soil profile.
The results of analysis showed that the materias of tsunami mud contain clay
fraction of 56.62 N; pHH2o,7.60; ca, 14.81 me/l00 g; Mg, 14.56 mellOO g; Na,
2.16 mell}0; Electric conductivity (EC), 5.67 dS/m; Fe,30.52 ppm; Mn, 66.96
ppm; N, 0.13 %; and P, 3.00 ppm.
The results of analysis of mineral sand fraction show that there is the
difference of mineral composition between the soil affected by tsunami rnud
(<500 m and 1000-2500 m from the coastal line) and the soil not affected by
tsunami mud (3000-5000 m from the coastal line). The soil affected by tsunami
mud has weatherable minerals (WM) higher than the soil not affected by tsunami
mud. Weatherable minerals come from the sea that will resist the weathering in
the flooded condidition. When tsunami occured, this WM were carried by the sea
to land which in turn increased the amount of WM in tsunami-affected soil. The
dominant wetherable mineral took the forms of fragmental rock and labradorit. A
side from those forms there had been found a lot of green hornblende, brown
homblende, augit, hyperstine and epidot. While in the soil far from the coastal
areas and not affected by tsunami mud the contents of green hornblende, brown
hornblende, augit, hyperstine and epidot were not found.
The soil affected by tsunami mud indicated are different from those not
affected by tsunami mud term of the structure of clay minerals. The soil near the coastal areas and affected by the tsunami contains the goethite minerals, while the
soil far from the coastal areas and not affected by the tsunami does not contain
those minerals. The difference is due to the fact that the minerals the iron of
ferromagnesian weathered and released the iron. The iron then changed to be the
goethite minerals because it contacted with the atmosphere on the top soil. The
soil near the coastal areas and affected by the tsunami has indistinct and
undominated of peak minerals, while the soil far from the coastal areas and not
affected by the tsunami showed clear and dominant forms. This condition occured
because the tsunami affected soil contains the amorphous material that disturb the
appearance of the crystal mineral. Generally, clay mineralogy fraction are
dominated by the amorphous material and kaolinite. The amorphous material is
indentified by the first temperature of the peak of endothermic betrveen 84-181"C
and the second one 270-276oC, and the first exothermic temperature 335-359"C
and the second one is 448'C. Kaolinite indentified by the endothermic
temperature for 576-578oC. The existance of kaolinite supported by the reaction
of difractogram with the first temperature 7.14 A - 7.rg A and the second one
3.56 A.
Due to its close distance from the sea and the influence of tsunami mud, soil
affected by tsunami mud indicated a few different characteristics of physic,
chemistry, and biology. The profiles near coastal areas and affected by tsunami
mud, have a coarse soil fraction because the tsunami wave carried and increased
the sand fraction to the original soil, and the hardness of soil is higher in the upper
horizon than in the lower caused by the formation of Si-oxidehydroxide and Fe-oxidehydroxide to be cementation, as well as the content of these profiles, soil
water is lower than that of the other profiles far from the coastal areas and not
affected by tsunami mud.
The pH of profiles (pedons) near the coastal line and affected by tsunami
mud increases more and more in the lower layers of soil profiles because of a
higher level of the cationic base. The cation exchangeable (Ca, Mg, Na) is higher
in the profiles (pedons) affected by tsunami mud than the profiles not affected by
tsunami mud, and profiles near the coastal areas contain ca<Mg<Na. The
tsunami-affected soil indicated were higher EC (salinity) than the soil not affected
by the tsunami. The EC is related to the contents of clay (0.29*), sulphate
(0. 59* *), sodium (0.+0**';.
The different biological characteristic of the soil affected by tsunami mud
are total microorganism. The soil affected by tsunami mud has more disturbed
(unstable) mikroorganism than the soil not affected by tsunam mud, because the
tsunami mud contains organic matter, higher pH H2o, and higher EC (salinity).
The degree of weathering of pedons was studied including at the juvenile
dan virile stages. Both of these stages shows lower ratio of weathering mineral
product and weatherable minerals (wMp : wM), cation exchange capacity, and
higher base saturation, ratio of calsium-magnesium
, ratio of fine-sandy and silty-
clay, and ApH.
The results showed that tsunami mud influenced on the pedoprocess too.
This is indicated by the higher content of iron (Fe) produced by weathering iron minerals. These iron minerals then oxidized to be goethite that resulted in the
broum colored soil (braunification). Salinization is a real pedoprocess caused by
the tsunami wave in which has the higher content of the soils with sulphate and
sodium which in tum cause the higher salinity (EC).
This research is canied out twelve kinds of soil family categories, i.e. Sulfic
Endoaquenfs, ashy over loamy, isohyperthermic; Typic udipsamments, mixed,
isohyperthermic; Ltthic Psammaquents, mixed, ishyperthermic; suffic
Endoaquepts', sandy, mixed, isohyperthermic; Aquic Eutruclepls, sandy, mixed,
isohyperthermic; suffic Endoaquents, clayey over sandy, illitic, isohyperthermic;
sulfic Endoaquepts, clayey over sandy, kaolinitic, isohyperthermic; Aquic
udipsamments, mixed, isohypertherrnic; Typic Endoaquepts, sandy, mixed,
isohiperthermic; Typic Endoaquepts, loamy, mixed, isohyperthermic; Typic
Endoaquepls, clayey, mixed, isohyperthermic; oxyaquic Dystrudepts, loamy,
mixed, isohyperthermic.
Guidance for soil management should be based on the change of the
ecosystem and soil cahracteristics, covering the following aspects: mangrove
replanting around pedon near the coastal areas; a rational management of
phosphate caused by higher amorphus materials; The addition of organic matter;
leaching the soil with irrigation to decrease EC and werease sulphate. This
research recommend that land use for paddy fields, ponds, and coconut,s
plantation with irrigation and drainage systems should be preserved.
Alternatavely, these areas can also be used for pasture and forages planting | en_US |
