Luận án phó tiến sỹ Địa mạo trầm tích ứng dụng rừng sác Gia Định

BO GIAO D{)C vA BAo T~o
TRUC1NG B~ HQC T6NG HQP THANH PH6 HO CHf MINH
NGUYfNTHfNGQCLAN
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TOM TAT LU~N AN PHO TIfN sf KHOA HQC DfA CHAT
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THANH PHO HO CHi MINH - 1994
LU~N AN DU<)C HOAN THANH T~I
TRUONG D~I HQC TONG H<)P THANH PHO HO CHi IVIINH
NgUdi huang d§n khoa hQc : TRAN KIM THACH
GlAo SVTIEN SI DIA CHAT HQC
Ngu('1inh~n xet I :
NgUdi nh~'n xet 2 :
Co quan nh~n xet :
Lu~n an se du(fc bao v~ t~i H(n DONG CHAM LUAN A:NNHA NUDC
hQp t~i Truong D~i HQc Tling H(ip Thanh PhC; w\ Chi Minh
Vao h6i . . . gid, ngay . . thang . . . . nam 1994.
Co thi tlm hiiu lu~n an t~i Thu vi~n Khoa HQc Tling H(jp
69, Ly Ttf TrQng, thanh rho H6 chi Minh

va Thu vi~n Truong D~i hQc Tling h(ip TP Hi) chi Minh
,.H04" NGU'(ANB VI$'r) DONG ,.BONG L04N AN
B1iicat bien
B1iithllYtri€u bUn
B1iithllYtri€u cat
=Sand beach
=Tidal mud flat
=Tidal sand flat
Bu'ng sail de
B1iitri€u cat cii'asong= Distributary mud sand flat
=Backswamp
CU lao song, c6n song: River island
Doi song
Bfun m~n
Be nt nhien
Bo~n song bo
B6ng bhg tam giac
cMu
B6ng thllYtri€u
Gi6ng c6
Gi6ng mdi
Giua gi6ng
GC!,ngang cat bien
Lu'<;ln cat song
=Point bar
BUnset
= Clayey silt
Cat-tho
- Sand - coarse
- trung billh=

- medium
-1$
- rilt m~n
- fine
- very fine
Ne'p nhan leo
= Climbing-ripple
lamination
=Tidal swamp, mangrove swamp IS~p la d<;lns6ng =Ripple lamination
= Naturallevee
= Abandoned course, channel
Delta plain
=Tidally inundated lowland
=Relict beach ridges
=Active beach ridges
=Inter-beach flat
= Barrier
=River bar
Tich chilt bien tie'n = Trangressive deposits
Th€m
Th€m bien khdi
=Terrace
= Open shelf
Thung lUngphil sa
= Alluvial valley
Tran tam giac chillI
= Delta front
Sp la phdng
=Even lamination
Set bUn

=Silty clay
Xien cheo
=Cross-bedding
D~C DIEM CHUNGCUALu4N AN
I. MVC 8!CH NGHIEN CUU :
D~ tai "Dia mqo trilm tieTzl[ng d{LngRllllg Sac Gia Dilllz" uu\.Ie
thlfChiQn nhilll :
.Yf.rri~t hQc thu~t, nghien ct1ucac d~ng dia m,!-ou<:ictnlng
cua mQt tam giac chau n~m trQn Vyn trong liinh the) Yi~t Naill va phat
trifn hifu bitt co ban cua mai tnlC5ngctra sang M ap dl.:ll1geho u6ng
b~ng song Oiu Long - vlfa Ida cua mi~n Nam Yi~t Nam.
.Yf. m~t ling dlfng, nhim VaGqui ho<.lchva pilat tri0n kinh
te dja phuong.
2. PHUONG PHAp NGHIEN CUD:
D~ tai ap d\lng phuong phap gicli doan anh may bay qua kh6a
anh ti 1~ 1/50.000 clla nh6m Dornbusch (1969) - thtfc hi~n ph~n lOn 0
dong bing song CU'uLong, dQc IDeoqu6c 1(>4 cii - ket h<;1pvai trlfc £lnh
do 1/50.000 va 1/25.000 va bQ anh may bay cua Rung Sac Gia Dinh ti
1~ 1/12.500, 1/10.000 VaGcac Dam 1980, 1987 va 1992 d6 l~p fa so do
dia m~o tr~m tich clla khu vtfc.
Cac badc thlfChi~n la giai doan IDeo poligon (Iii c6 ki~m tra thlfe
dia theo 1(>trlnh dinh san va chinh ly ho~c be)sung chi tiel. Trong khi
d6, b6 tri cac 10khoan theo tuyen thich h<;1pvdi qua trlnh pilat tri~n eua
tam giac chau n§y. Df. tai dii thlfChi~n hon 60 10khoan dQc tuyen Nhil
Be-Blnh Khanh- Yam Xay-Long Th~nh-Long Hoa-C~n Th~nh va hall
10 10khoan 0 cac vung Thi~ng Li~ng, Giang Chua, Do Hoa, Tam Than
Hi~p, An Thai Dong, Ly Nhon, Cu Lao Phd L<;1i.Dong thai, t;:Iegia uii
phan tich h6a 54 mall dat , phan tich tMnh ph§n h~t u(> 9S mall (Jat,
chung thuQc cac don vi tr~m tich khac nhau trong khu vtfc ; theo doi SIf
thay d6i trong qua trlnh tnfang thanh cua chung, tu do, d6 nghi huang sU'

d~ng ho~c khai thac h<}p19.
Cuoi cling, lac gia ket h<;fpvai d"t nhi6u tu li~u mai v6 call truc
tdm tich, moi truong triim tich, Wong lac gilia cac lo<;tinang IU<;fng
song- tri6u- giG- dong song Jen vi~c hlnh thanh cac tam giac chao tren
the giai, d€ ban v~ qui luc;ithlnh thanh va phat tri€n cua tam giac chao
song E>6ngNai niiy.
3. NHUNG £>ONGGaP Mal CUA LUA.N AN :
3.1 L~p ban d6 dja m<;totriim tich tl J~ 1/25.000 cua vling
nghien cU'u,vai mOt so lo<;ttgi6ng c6 ho~c trung gilia gi6ng c6 chua
du<}cd6 cc;ipden tu truac, cling nhu mOtso don vi dja m?o tdm tich cua
tam giac chao nay, nhling tinh chill 19hoa cua dilttrong tung don vi.
3.2 Ph~c h6i co che tr~m tich co ban cua cac don vi tdm tich
trong tam giac chau, dua ra qui luc;ithlnh thanh va phat tri€n cua no do
anh huang cua cac dc;ipthuy di~n va thuy nong.
3.3 £>6nghj huang qui ho?ch dt!a tren cac d~c tinh dia hlnh,
dia m?o, oja chill cong trlnh thuy van, moi tru'ong tt! nhien, o~c tinh dilt
oai th6 nhuBng.
4. Y NGHIA THVC TIEN CUA LU,A.NAN :
Ket qUC!nghien cU'ucua d6 tai la co so khoa hQc cho cong lac qui
ho?ch, phat tri6n huy~n C~n Gio noi rieng va thanh pho H6 chi Minh
noi chung. £>6ng thai, d6 tai con du<}csU'd~ng trong chi 0' 10san XUfil,
nghien ctiu khoa hQc va d trong giao d~c.
2
5. CAD TRUC CUA LUAN AN :
Lu~n an g6m 130 lrang khCmgkE hinh anh va phu lue vOi 55 lai
li~u tham khao trong va ngoai nude,t6ng cQng khoang h()n 160 lrang .
NQi dung g6m ba ph§n, 8 chuang, kh6ng k6 ph§n mC5a~u.
Ph§n mC5d§u : ml}c aich yell du va phuong phap nghien C\lu.
Ph§n I : B~c ai6m aia ly tlf nhien, kinh te nhan van va aia
eh1t.

Ph§n II : Ket qua nghien e1h1va thao lu~n.
Ph§n III : Ket lu~n va kien nghi.
6. TAI LI~U THAM KHAO
Tae gia dii tham khao cac tai Mu v~ di~u tra co ban tren aia ban
huy~n Duyen Hai cua : Ban Phan Vung Kinh Te Tp.H6 Chi Minh
(1988), H6 Chin (1983), B~ng HI1uDi~p (1983), Bo~mBia ch1t Tp.H6
Chi Minh (1989), B~ng C6ng Minh va Nguy~n HI1uNhan (1993 va
1994), Bili PM My va D~ng HI1uNgQc (1983), Nguy~n Hau Phudc
(1989), Trh Kim Thgeh va nnc (1978 va 1983), Huynh Trung va nec
(1983), (Xem thuml}e tham khao trang quy€n lu~nan).
v~ s6li~u 15 khoan, lac gia chI tham khao 3 16 khoan eua Boan
dia eh1t Tp. H6 Chi Minh (LK821, LK822, LK827).
M(j DAU
Rang Sac Gia 8inh Ja d0ng b0i phu sa cua slmg 80ng Nai
giap ranh vdi bi6n Dong, c6 di(:n rich Ii! I IOOOOha,bao g6m chu yell Ii!
huy~n Duyen Hili TP H6 chi Minh mOLben, va mOLph:in cua huyt;;n Long
Thanh (tlnh 86ng Nai)va huy(;n Long Phil (tinh Ba Rja- Vang Tau) mOt
bell.
Nghien CUll nay c6 lrqng tam la huy~n Duyen Hili.
HuYQn Duyen Hili TP H5 chi Minh, nay Iii huy~n 01n Gia,
ou<JCsat nMp vaG TP HCM k6 ta nam 1978 nh~m ml;lcoich tang cuang vj
the kinh le, xii hQi, quac phong.
Trude nam 1975, Can Gia Iii mOt vung oat rQng, nguoi lhua,
ou<Jcquan tam den chu ye'u la VIml,lcdich chinh trj vii quan slf.
Sail 1975, nha't la k6 tu nam 1978, C:in Gio da du<Jcvlfc d~y
va phat tri6n d:in. Day la cL(angBduy nhat d6 cac tau be nudc ngoiii ho?c
trong nudc vaG thanh pha H5 chi Minh. VI the' rat nhi~u d~ tai nghien CUll
du<JcthlfChi~n d day: dja m~o, the)nhuong, tham thlfCv~t, dja cha't, ye'u to'
bi6n trong vung vjnh Giinh Rai, thuy tri~u Bi6n Dong Tuy nhien,
nhii'ng nghien CUlltrudc day thuang dU<;lCtie'n hanh dQc I~p vii il lien hQ

m~t thie't vdi nhau, chua d~ c~p de'n Hnh chat da't trang mai quaD hi;:cua slf
hlnh thiinh va phat tri6n cua mQt tam giac chillI, d?c biQt la tam giac chau
n~m trQn Vyn trang lanh the)Vi~t Nam. VI v~y, du c6 nhi~u kh6 khan, d~
tai " Bia mq.o [dim [ieTzllng d{mg Ri'tllg Sae Gia BinTz" v~n dU<;lCthlfC
hiQn.
1 lYHJCDlCB YEU cKu :
Cong lac nghien CUll d5ng bang phu sa mang ten Rang Sac Cia
Dinh c6 3 ]<;Iiich quan trQng :
1 Phal tri0n kinh te dia phl((jng.
2 Phat tri6n hi6u bie't cel ban vf- moi truang ctia song, hall ap
dl;lng cho d6ng bang song Cl'(uLong.
4
3 (fng dl;lngVaGqui ho'.lch va phCtllriGn huyi;n Can GiG.
11 PHUONG PHAP NGHIEN CUU :
- Gdi doan pictol11ap 1/25.000.
- Giai doan anh vf; [inh va <'\nhmay bay tl If; 1/10.000;
1/12.500 - dtfa [heo kh6a giai doan cua Dornbusch (1969) - rut nh6 l~i
1/25.000 cho toan Rang Sac Gia dinh.
- Ki~m tra 0 thtfc diet, khoan, Ia'y mall theo tang d<1t.
- Philo tich cc519boa, long h(/p s6 lii;u, c6 [ham khao cac
tai Mu cua cac lac gia tntac.
- Ki~m tra l~i 0 thtfc dja.
- Len ban d6 dia m~o tram tich vung nghien call.
- T6ng h<jp, c~p nMt h6a cac quaIl di~m cua cac nhil
tram tich hQc tren the' gioi dtfa tren cac tu' lif;u l11oinMn du'(;5c,hoan thanh
lu~n an.
5
sa 80 cAc Budc TIENHANHDETAl NGHIENCUU
THAO LuAN BAN DAu
a Xac djnh ml,lclieu

b Thu thij.pcac thong tin
C Lij.pke ho~ch nghien cU'u
Tu Ii~u tham khan v~ +- Kh6a anh may hay II
dja chat, cau truc vung ANH VB TINH l~ 1/50.000 cua nh6m
NC. cd ban ve trilm rich ANH MAy BAY Dornbusch ve diLl nwo
cua cae TGC tn~n the trilm rich CULtTGc.
giai. -+
~
~
La khoan ki<smIra
-+
+- Phan rich 19 h6a dfll.
DON V~D~A M~O IIdenghi huang sl'rdung.
~
D~AM~O TRAMTICH
RUNG sAc GIA DJNH
~
~
QUI LUA T HINH
THANH TAM GIAC
CHAu
~
QUI LUATPHATTRIEN
TGC TRUdc VA SAD
KHIco cAc 8Ap
~Iheo m() hinh
~ ~ S = f {Q. R. D. M}
HudNG QUI HO~CH VA s0
m)NG DAT DAI +
TAl NGUYEN SINH VAT

~ .
I TONG KET.BAN 80.8Ao cAo I
It
t>
PHAN I :
CHVdNG 1 DAc DIEM D!A L
Y TV NHIEN - KINH TE -
NHAN VAN:
Huyt;n C~n Gia vdi dit;n rich bon 600 km2, chiem lrl)n phan
phia Nam cua tam giac cMu song 8iSng Nai (Nha Be-Can Gid), vdi
m<)nghidi song r<)chchang chit. Dja m~o ph~n Idn la d~m I~y m~n vdi
cac gi6ng cat cao tu 1 dGn3 met chao ngang cac khu vlfc khong c6 ho~t
dQng cua song m<)nhme . Con a vung yen song thl c6 cac h~ th6ng de
tlf nhien hay de tri8u, cac tr~m rich ciSnsong, doi song .
Day la rung ng~p m~n d~c tning cua vung nhi~t ddi gi() mua
c~n xich d<)ovdi cac thlfc v~t chinh la dua nudc, dudc, mam, gia, su Vyt,
b~n, cha la, rang . Anh huang cua chill dQc khai quang ciing nhu ciia
vit;c pha rung bua bili vao nhung flam 1970 dii lam milt di mQt s6 ldn
sinh v~t d~c trU"ngcua vilng . G~n day, vdi chG dQ giao dill giao rung
cho dan, C~n Gia dil c61<)iduQc tham th\fCv~t nhu xua.
Dit;n rich dill qua rQng, I<)ibi chia cat bai M thong song r<;lch
vdi dill thuQc lo~i lun yGu, M th6ng giao thOng chu yGu bang duong
thuy. TuyGn Quang TP H6 chi Minh - Blnh Khanh - ch GiO duQc th\fc
hit;n flam 1978 vdi quyGt tam ldn cua Nhil Nudc dii ph~n nao t<;lOdiGu
ki~n cho nguai dan C~n Gia tiGp xuc duQc vdi cuQc song ti~n nghi va
tuong doi van minh cua thanh ph6 HiSchi Minh. Nhung ,nhln chung, ddi
song nhan dan cac xii vilng sau viin con qua co c\fc, lam IU,chua c6 I11Qt
phuong tit;n giai tri nao dil mang tiGng la nguai dan cua thanh ph6 HiS
chi Minh.
D6 la mQtvilng c6 dia ban phuc t~p, song r~ch chang chit, (Ii

I~i kh6 khan, tr~t tlf xii hQi khOng 6n djnh, nen nhG'ng tai li~u diGu tra
nghien cUu v8 vung n~y con h~n ch6. Tu khi tra thanh mQt huy~n cua
thanh ph6 H6 chi Minh, Rung Sac Gia Dinh dUQCNha Nudc quail tam,
7
t~p trung nghicn cuu, tuy nhicn, tat d CC)ve roi r~c Ie te . Cil I1hl11 1\.;II~
hup ve ulc khia canh nay can du'<;JcthlfChi(~nd0 I~Odieu kicil ch,) Lilli
hoach va pha I Irien kinh Ie hQp ]9 hOD.
CHuaNG ]1 D!A CHAT KHU VVC :
11-!-N~nc1::icung:
Nen del vay bClClay phan tic va dong cua RL(ng Sac GI~I
Dinh (RSGD), chay Ii:(Thu Duc, Long Thanh, Ba R!a den I~n Long I-Lit.
Vung Tau va Long Son g6m au lo~i oil Ii:(tram tich (Oelphien set. phiel1
vC)i,phien than, cat ket), den dil xam nh~p (granit, granodimit) <I Lti
phun trao (basal I, andesit ). Gilia trung tam cua RSGD, c() nH)1Ch'HI1
del g6m chu yeu la andesitobasalt, no chang to n~n oil khC)Jlgnam <ill
lim duoi lOpdat m~n.TMt v~y, 16khoan 821 va 827 cua c1o:tnc1i~1 Lh~lt
thanh phe) cho tiel co dil (j dQ sau 152,lm va 226,8m ; hai mOl klwal1
tlm nuoc (j Tam Than Hi~p oa gi;ipoil n~n (j khoang 176m; mOi khoan
cua Lien doan Dja chat 6 (j Nha Be g~p oil (j 230m. Tu6i clIa loal l1a
xam nh~p nay ouQc dinh la Jura muQn - Creta. Con lo~t da Irilm liLh l()
hon bi lo~t nay xuyen dt co tu5i tll gilia Triat den Jura.
II-2 Tram tich c5 :
Nam dClCtheo tri6n cua n6n oil cung, co phLIsa C()v(Ji tinh
phan 101'blnh hang (nam ngang) rat ro. V~t li~u g6m cat chen vdi s~ln
va sel. Tu6i cua phil sa c5 chua OU<;5cxilc djnh ro. Theo dc lac giii
truoc 1975 thllo~t nay co tu5i la Pleixtoxen. MQt so lac gi:l sall Iens,
dlfa vaG c5 sinh va tectit, xilc djnh tu5i la Plioxen-Pleixloxen.
11-3 Tram tich moi :
Lo~1 tram tfch nay tnli tren mQt di0n tfch hun I()()()()()
hecla, g6m 3 nh()m : long song, bo bien va dam m~n ; c1L(.Jcth:ll1h L.lp

each day tren ch1oi5000 nam.
8
PHAN II :
CHV0NG III £>~AHINH£>~AMAO RUNG SAC GIA DINH :
Cling nhu d6ng bang phu sa cua nhi€u tam giac chao tren
the gidi, d6ng bang song D6ng Nai g6m toiin Iii v~tli~u phu sa, co hlnh
3 goc rfit 1'6net: do Iii mQt tam giac chao dung nghia cua tu DELTA. Ba
goc nfiy Iii Nhii Be, vang Tau, Cfin GiuQc. Phia dong giap vdi D6ng
Nai, phia tay giap vdi Long An, phia Dam vdi Bi~n Dong. Philo Idn cua
d6ng bang n~y la huy~n Duyen HcliTP H6 chi Minh (nay Iii huy~n Ciln
Gio).
.:. Dia hlnh co 3 d~c di~m chinh Ii:!:
- Day Iii khu We chang chit song nhanh toa tu song
D6ng Nai, song Thi Vcli,vii song ViimCo.
- Ph§n ngoiii bi~n co dia hlnh cao hdn bell trang dfit
lien do s11hi~n di~n cua nhung IU<;1ncat huang dong
- lay t<,tonen bCii
song bi~n ma tit dia phudng gQiIiigi6ng.
- Cac long song co dQ sau khac nhau. Nhung nhanh
tieu nude quaD trQng co long hyp se co dQ sau IOn; vii ngU<;1cl<,ti.
.:. Dia m<,tog6m hai philn chinh : tam giac chao trang va
tam giac chao ngoiii.
0 Tam giac chao trang Iii ph~n tr~m tich tier xuc du<;1C
vdi khi troi, luon luon Dam IreD mtfc nude rong cua ky trieu xuD'ng, vdi
nhung ddn vi dia m<,tod~c trung cua I11Qtd6ng bang phIl sa . TruCiebel
la nhung long mang chi chit va uD'neo vdi nht1'ngde ttf nhien nam dQC
hai ben bo, nho cao len khoi l11~tnude trung blnh. No chi xuat hi~n ci
di~m ph<ittan nude, tlic Iii giln Nha Be, vii bien mat v~ phia cuD'idong.
Hai bell dong song, Iii khu vtfc trang, dU<;1cgQi la bung, d~l11,ella, h(\
vling m~n.

9
Noi bG bi6n, thuang c() nhung thay d6i dOt ngOL Day ]a
noi ma ho<;ltd(mg cua song tra nen nh6 cHin,chat t[(1m tich cua sCJIlgbil
d§u bi s6ng biEn va tri~u khuay trQn va ]~ng dC)ngtra ]<;lidE t~IOth~lnh
cac gi6ng. Cac gi6ng moi aC§n GiG Dam cao ton mtfc biEn chung 3m;
nhung tu bai biEn, dia hInt tra nen thoai d§n, t<;lODen mOt bai Hly thuy
tri~u se n6i hin ]en m~t nuoc khi lri~u xu6ng.
0 Tam giac chau ngoai ]a ph§n tr§m tich khong bao
giG dUClCnho ]en khoi m~t nuoc, keG dai tu bGbiEn C§n GiG ra den BiEn
Dong. Day ]ii noi chaa nhi~u khoang san d~c bi~t Dam duoi d<;lngsa
khoang nhu g]auconit, i]menit, magnetit, zircon . N6 bat d§u cho mOL
don vi dia m<;lo]a Iran tam giac chau - noi c6 tri~n d6c lOllnha't cua loan
bO tam giac chau. Sau d6 tri~n tra Den thoai d§n.
CHUaNG IV ca CAD TRAM TICH CUA RUNG sAc G]A
DJNH:
IV.l ca'u truc vi mo :
Ca'u truc vi mo cua tam giac chau lieu biEu da du~)c
GILBERT ma ta Dam 1885. Tam giac chau Rung Sac Gia Dinh , du ]21
mOt tam giac chau kiEu d<;liduong, cling g6m 3 ph§n:
- Ph~n Dam blot hang ben duoi chan s6ng, mong, min
h<;lt,gQi Ia bOday (bottom set),
- Ph§n Dam xien, ngay noi tier xuc voi ntiOCsong va
nuoc biEn, g6m v~t Ii~u tho (cat va s<;lnmin), gQi ]a bOd~u (foreset),
- Ph§n nam ben tren bO d§u, phia sau trong khu vtfc
da't li~n, g6m v~t ]i~u mill, s~p lOpblnh hang, gQiIa bO tren (topsel).
M6ng c6 bell dudi c6 thE bang CIa,bang phIl sa c6 ho~c phu sa
moi da dUClC13:ngt~ trudc d6. Mlii ten chi hudng tang truang cua tam
10
giac chau, m<)tthu b6i tfch ngang . gQiIii b6i ket (accretion), khac bin
voi b6i tlch dung, gQi la tich lu (deposition) m6 tii d dia tang h<)cc(;

di6n.(Hlnh IV.1)
Rang Sac Gia Dinh hi~n nay c6 b<)tren la da't m~n yen bi~n.
tren phil rang lily mi)n (mangrove); b<)dau la tri~n cat ven bi~n 0 Gin
Gia; b<)day la lOp bun min pha set d ngoai khdi. Nghien CUlltram tich
hQc cua Rung Sac Gia Dinh e6 ml}e dich theo doi st! thanh I~p va tan
bien cua b<)tren va b<)dau. cung st! I~p di I~p I~i trong qua trlnh lien
hoa eua tam giac chau, v~ st! tram tich cila b<)day. , ~ ~ "
! C;\; ,; ;U\ci H;\ ,::
! ._.~_~~_.l~':~'~~- !i2.f
I
j
L N~ " " ~
Ndi tran tam giac chau (delta front) c6 hai moi traCing tudng
phan nhau. Ndi philn c6 st! ho~t dOng cila dong song (long mang), eha't
trilm tich phong phu nha't voi nhii'ng ngang toa ra tu ctta song (c5n d<)c).
Ndi phan khong c6 ha~t d<)ngcila song, s6ng, tri~u va gio baa tu bicin
vao mai mon bai thuy tri~u va t~o Den nhung c6n cat, gQila ga ba bi~n
(beach ridge) hay con gQi la gi6ng. Gi6ng d day g6m cha't trilm tkh chu
ye'u la cat mill va bun, thuang e6 mall yang dd, voi cffu true tram tich Ja
xien eheo trung da phudng. MOt s6 gi5ng c6 ehi~u day d~t toi 10m. Day
la mt!c thuy ea'p ngQt duy nha't cila Rung Sac Gia Dinh, dil tru lu<jng th~t
It. Tinh Den de kern va voi tri~n khong 6n dinh, gi6ng thuang bi tl}t 1('5
duoi suc s6ng va dong Iii. Tuy v~y , day cung la ddn vi tram tich c6 Den
m6ng cong trlnh vung chile nhat trong tat d cae ddn vi tram tich hi~n
nay trong khu vt!c nay. Day eung 13da't thich h<jpclio cae vuan cay an
trai hoi)c boa mall cila vung can Gia vii Ly Nhdn .
IV.2 ca'u truc vi mo :
G5m 3 nh6m :
IV.2.1 Nh6m ba bi~n:
cac lo~t gi5ng d day thuang ch~y song song nhau va song song

voi ba bicinhi~n t~i. Giua chung 13cac trung giua gi6ng , g5m v~t li~u
11
mjn to' hai dlnh gi0ng loOt xu6ng sail moi cejn mua hay khi c() hCio.NhC!
co nudc to'trong gi0ng rl fa, thtfc v~t () day kha phung phu, L1(JI1gg()P
mOt lu0ng mun can trong don vj niiy. (5 day co nhling lach I1Lr(icnIle')
giup thong thl.Wngvdi nudc 0 song nhanh cua cac song IOn, t~IOncn mOt
m6i truong nudc 10 - vdi thtfc vc;itchinh la duoc - va trung, thuC!ng
xuyen ling nudc. V~t li~u tr~m tich chu yell la bun va set, vdi nhi6u xae
bil thtfc vc;it, Iii di~u ki~n t6t cho vi~e pIlat sinh ra mOl!uL}ng phen ticm
tang, du khong dang kf Him.
Neu khoang cach gilia cac gi0ng dO vai cay sC), sail giong
thuong xua't hi~n cac ao , yang hay Ii;lChnude man trung dL)thuC!ngc1Lruc
tich tl.}nhling vc;it Ii~u min nhu bUn set vii nhieu chill hl1u CLioDo la o(in
vi bung sail gi6ng. Trong giai doi;lnd§u, bung co khii Dang giao Iuu vdi
hen ngoiii, qua nhling trung nhe)gQi Iii "pha". V6 saD, stf giao IUDcham
dU't,bung bi co Ic;ipd§n vii chet . Xac bil thtfc v~t t':lOngu6n sulphur cho
stf t6ng h<;ippyrit rift phong phli. Bay la cae tui pIleD kIllIng khiep nhat
trong khu vtfc d§m m~n (xem bang t6ng h0P v~ phan t!eh thanh phc1n
h':lt dO vii hoa hQc cua cae don vi tr§m tich then 10khaan).
PIlla hen ngoiii eoa gi6ng Iii bili cat co kich thude h':lt mill vii
trung, cat th';lch anh s';lch, chda to'lO - 25% manh vo so 6c nat vlfn, Dam
thoai thoai ra khoi : do Iii cac bili thuy trieu. Luc triell rang, loan bO bCii
phoi ra khl troi eho tha'y nhling chi tiel dia m':lOd~e sac nhu nhling ncp
nhan IO';liIOn(mega-ripplemark) xen ke vdi nhling 1ong l':IehSail .
N6i tier vdi bili thoy tri~u n§y Iii cae luon cat dC/ctt)a ra to' cac
cii'a song chlnh , t':lOra don vi doi bifn rift d~e sac () pIlla Nam eua Ly
Nhon va pIlla Nam eoa C~n Gio (eii'a song trong vjnh Giinh Rai). V;}l
Ii~u 0 day cho yell Ia cat miD va bun tho chen Hln vdi nhling thau kinh
cat th6 vii S':ln.
12

IV.2.2 Nhom c1amman:
Drjn vi tra m rich nam hoc theo chan cac gi{mg ca l nl1L(i'j
phia biic can Th';lnh, Ly Nhcin, Gi6ng Chua; g6m chu ye'u Ia bun rha set
ho~c it cat min va mull xam xanh, hoan loan m~n du'<;jCgQi Ia c1all1hCm
man. DQc rhea chan gi6ng, khong baa giCidQ m?n vu'<;Hqua 1%, de) ICl
i
nha nudc ngam tham tll cat gi6ng ra vao thai di6m dau mua kilo. Doc
rhea veIl song, dQ m~n cling giam, nhat Ia vao mua mua. MQt s6 tnl(ing
hQp ca bi~t, co th6 co dO m~n V1JQthejndO m~n cua nudc biEn. do tricl!
dua van t';li de) (trong Io';ltphu sa c6 hejn c1Blnh Chanh, Phil UlI11.NhC!
Be).
Con nhling noi trling thap, bi ng~p nudc quanh nall1 va hi
kh5ng che' bC1itri~u cao va thuy cap cua dat li~n till thuQC dejn vi da111
lay man. Tinh chat d~c bi~t cua don vi nay la v~t'li~u g6m lOan la sel it
bun, giau mull va pyrit, va lien tl,1Cbi hoa lay nhao. DQ tnlC1nglhanh
trung blnh Ia 3 - 3,5. Qua trlnh truC1ngthanh cua dat dam Hly m~n c() lh0
rhea d6i duQc bang m~t, do slf thay d6i mati cua dat tU xam xanh l1cn
xam ll,1chay xam nail c6 chua nhling d5m d vang . Thtfc v~t sinh s6ng
d6i dao trang don vi nay t<;todifu ki~n thu~n lQi cho stf pilat sinh CUd
phen ti~m tang. C6 hai hi~n t1JQngxay ra c1 day:
. Noi nao Qat c6 slf th~ng du cua ki~m carbonat (ehLI
ye'ula CaCO3) , cling vdi stfoxidhOacac hQpchat sulfur, H2SO4rheJilg
thich ra se bi vo hi~u h6a gan muc pH trung boa va chung ta thflYlrung
dat dam m~n d6 kho giG co stf hi~n di~n cua nhting kim th<.!chcao.
Trang di~u ki~n nhu v~y, Qatm~n khong chua pilat triEn (vung Thicng
Lifng).
. Nrii nao dat c6 hQpchat sulfur tMng du, terela IL(c.)ng
v6i trong moi lruling khong du cao dE lrung boa het ILl<;:ingacid dla l1:(l,
dat se giam pH - lerc gia tang H+ - till Aj3+ tlf do du<;:iCphong lhich ra
13

moi truang do slf boa tan khOling v~t set va slf ngheo nan cua baz lrao
d6i. KGIqua cuoi clIng la dill co pH thap - lhuang la giITa3 va 4 - nghco
baz IraQ d6i, giau AP+ tlf do d~ trao d6i. Cac IOC;lioat suIfat chou phcn
do dU<;fCd~c trung boi slf hi~n di~n cua jarosit mall yang njm lhanh deJl1l
hen ngoai m;)t dill ( nhu dilt d§m m~n thuOc vung Vam Xay, nong
truang qu~n Go vilp, nong tru'ang D6 Hoa ). DO chua cua oat nc1yse
tuy thuOc vao lu<;fngpyrit hi~n di~n va dOthong khi cua oat.
Dilt d§m mi)n phat tri6n mai, nang caD b~ m;)t dc1n, tru
thanh d6ng thuv tri~u . Ndi day, slf tr§m tich chi xay ra vao Ide Iri0u
len; do do, v~t li~u giam lu<;fngHfngw rilt nhi~u. va kieh thu(Jc h<.11cling
rilt min. Di~u ki~n dng ng~p khOng keD dai nen khong eo lu(jng phcn
ti~m tang nhu 0 ddn vi trltdc (ilp Blnh Phudc, xa Blnh Khanh) . Day la
dilt mi)n hoi)c 1<;1chu khong phiii chua. Dilt d6ng thuy tri~u phat tri6n
nhi~u 0 phia bJc C§n GiG va phia lay nam Long Thanh, keD dai den t~n
Ba Ria. Vao mila mu'a, nong dan tr6ng du'<;fCmOt vt.llua, nhu'ng vdi nang
suilt khong caD.
IV.2.3 Nhom long song:
Day la ddn vi b6i tich cM yeu cua Rung Sac Gia Djnh.
Cac long mang co chi~u rOng di tu 1 dcn 1800 met va chi~u sau di tll
0,5 den 20 met. G§n nhu60% chi~u sau chung cua long mang d0u du(jc
lilp b5.ng V?t li~u' tr§m tich soot thai ky khong co lU. Hong eua long
mang thuang co tri~n caD , nhu'ng ndi nao co chli'a tu 10% sel sl1lectillru
len thl hOng tro thanh thoai thoai va day bj bOa nong rat nhanh. Cae
long mang chinh 0 day g6m co : song D6ng Nai (Soai RC;lP),song Long
Tau, song D6ng Tranh, song Thj Viii, rC;lchTa Chen (Co May). SCmg
Vam Co khong n5.m trong dja ph~n cua Rung Sac Gia Djnh, nhung da
dong gap IU<;fngnude va chill tram tich khong phai nho eho khu vlfc
nay.
14
Cac long song d~u bj anh huang loan 00 eua han nh~l

lricu, do v~y tr~m lich a long mang va hai hen hd xay ra ILCngch~fJ
lrong ngay. Khi trifu xu6ng, phu ,sara bi~n g6m co hal fJhein .
- Ph~n Id hlng duQc lai lrang nude,
- Ph~n day trUQldai hen dudi.
Kjp 'khi tri~u len, v~n t6c ra bj tri~l lieu, loa n bt) v~l Ii~u
Id Ittng rdi t~i ch6, con v~lli~u day ogling di chuy~n xuoi dong. Sau d6
trifu xu6ng va qua trlnh tha nha't l~i tie'p dien. Cho nen lram lich va x6i
moo xen ke nhau,lam n6ib~llen mau thuanC<Jban eua khu v~cccLca
song. 0 day khong th~ ap dl,mg qui lu~t bo 10 bo b0i cua lrung 111uhay
thuQng 111usong. MOt bo co th~ vua la ma cling vtla b5i, lUYeon nudc.
Ke't qua hi~n ra la do cuOc da'u tranh giua dong ra va dong vao.
Be'n mua W, dong ra la ap da9 VIv~n l6c kh('ji d()ng qua
IOn. V~t li~u thO nhu cat va cuOi tra thanh Id Ittng, nen tr6i lu0l ra bo
bi~n, d~ khi g~p tri~u len, chung l~i rdi xu6ng day nudc nhu set va bun
cua mua nudc ki~t.
M~t khac, tri~u bi~n cling anh huang ra'l nhi~u den nhung
song chinh trang vung phl) 100 ctta song nay. Tudng lac giua lri~u ra va
tri~u vao tu nhi~u huang dEn cac song nhanh khiEn l5n l~i nhicu do~n
song vdi pha tri~u ahai d~u nhu nhau. 80 la cac ddi giap nude. 80 dao
dOng mt}c nudc tri~u H a hai khu vt}c ctta song Soai R~p-Nha Be va
Long Tau-Thj viii hdi khac nhau mOt it. H a khu vl/c dong flam d~l 3,3 -
3,4 met, trong khi khu vt}clay biic chi d~t 2,6 - 2,8 met. Nhu v~y, vung
Long Tau- Thj Vai chju anh huang cua tri~u bi~n nhi~u hdn VLlIlgSoai
R~p-Nha Be, laC la thai gian ng~p m~n lau hdn. KEt qua nay dU,5Cphan
anh r6 tren cae adn vj tr~m tich eua hai khu vl/c : vung SoCIiRe)fJ-Nha
Be g5m cae de thuy tri~u cling vdi sl/ t~o I~p cac gi5ng ca t dqc ven bo
15
lay Ly Nhon; trong khi vung Long Tau-ThiVai g6m loan v~t li~LItram
tich bun set cua dam m~n.
Nha stf phan bO'trung thtfc theo anh huang kep cua dong

nudc song va trifLl, don vi b6i tich long song tra Den d~ phan bi~t. D6 la
cae de ttf nhien, de thUy trifu, bili b6i, doi song, c6n song , do~n song b6
vdi nhung lo~t tr~m tich mdi va cu. Tuy don vi tr§m tich, chat tram tfch
aday c6 th€ la cat, bun, hay bun set vdi thanh ph§n v~t chat huLl co
khOng cao (#3%). Day khong phai la don vi phen quail trQng.
CHUaNG V QUI LuA T HINH THANH
Stf phan bO', dinh hudng va dia hinh cua mQt tam giac chaLl
thuang duc;fcki€m soat boi nhifu ye'u to' nhu : khf Mu, lu'Uluc;fngdong
chay, suc n?ng tdm tich, qua trinh tr~m tich cii'a song, s6ng, tri~u, gi6,
dong nudc, tri~n dO'c,kie'n tgOva dia hinh cua b6n tho nudc (Hlnh V.l).
Chung qui c6 th€ phan ra 3 nh6m :
- Qui lu~t kie'n t~o,
- Qui lu~t thUy dQng,
- Qui lu~t cLIngung cha't tr§m tich.
V.I Anh huang cua kie'n tao :
Lich sii'dia cha't cua tam giac chao Cii'u Long va D6ng Nai
dil c6 3 thai ky lieu bi€u nhu sail (t6ng hc;fpsO'li~u cua Biwas 1973,
Fontaine, Delibrias 1974, Kawamura, Laming 1974):
-Tli 2000 Dam tra l~i day: bi€n khOng lui ra dang kE.
- Tli 5000 Dam de'n 2000 Dam : bi€n lui ra kha nhanh.
- Tli 11000 nam de'n 5000 Dam : bi€n trail vao kha
nhanh.
16
- Tv I WOO n:1111ln'j VC lrude : mue hien i'j mLre - 70mel
doi vdi mLje bicn hi0nlal do hlen rll11'a khLji.
Theo quan niell1 linh. hien tien va lui nhu v~y la do I11Lje
bi~n Dang hay hq tren hlnh dien loClncau. Theo quan ni~m d(mg, hi0n
tu(jng nay do n~n dJ SlJp xu()ng VCInJng len theo nhip. D6 la hm.lt (10ng
kien tqo.
ThLje v~y, boat e1()Jlgklen Lao da t?O ra cae ]oal dJt gay

then nhung phuong khae nhau.Tl'uoe hella 10?l dut gay Thea huong lay
b~e- dong nam, trong d6 (1l([g,ly doc lheo hudng Bien Hoa - Vilng Tau
la khong ehe. Gan nhu thiing g6e voi loat nay e6 lo(ltdut gay lay Ham-
dong b~c, ch(lYtv Phil Lam den Thu Due. Cii hai nh6m nay t,.tora khoi
WP nam Trangkhu vLjeNha Be - NhOnTrqeh - Vilng Tau - Go Congo
Chinh ehuy6n d<)ngSlJp]un e1()da tan nen hlnh dqng eua tam giJe chao
D6ng Nai ngay nay. SLjHang can eua khoi Long Thanh - Ba Rja va eua
khoi Thu Due - Trang Bang 1a nguon g()e eua lu<;5ngtram tich manh v(j
dlia v~ Rung Sac Gia Dinh, do cae dong nude loon h6a Ire la song D6ng
Nai, song Be, song Saigon, sfmg Vam C6 Dong va phan nao song Thj
Viii. Cae mili khoan eho thay tv hac xuong Ham, ehi~u day eua tn1m tieh
Pleixtoxen dt mu<)n tang ddn : 40 met (j Nha Be, 70 met (j Tam ThfJn
Hi~p, va 130 met (j Vung Tau. Kh(mg e6 noi naG (j d6ng bang sfmg Cl'(u
Long ma sLjh(l tri~n 'theo han Ie kien [,.10Iqi quan trc;mgnhu v~y.
V.2 Thuy d6ng hoc eua l1L(oemat:
Van Ham 1953, Bales e1axay dung du<;5enguyen I} thanh I~p
tam giae chao bang cae qui IU~1thuy dOng hQe, gqi la dong l()ng (jel
flow). Theo Ong, e6 3 IrLrUnghOp xay fa, khi m<)t dong s(mg L1ilLr
ngu6n xu6ng g6m nude ngql. ehLrae1ayvat li~u trdm tich , eh:1Yvan mL)1
bon Irdm Itch; ILlYlhu(JCVCIOSL(hien d6i eua dO m~n, nhi~l (10 V:l Slre
n~ng tram tfeh gay ra S~(khae hi01 vc Ii trQng . Tam giae ehau s(mg
17
D6ng Nai roi van tn1ong h<jptha ba, tac la dong song it di).m d~c di vao
khO'i mtac bi€n (dong nhu<jc n6ng hypopycnal); sl! trQn I§n then chicu
can khong xay ra du<jc, do vi).ydong to'ng co d~ng lOp (hinh V.2 cua
lui).n an). Dia m~o cua mQt tam giac cMu se tuy thuQc van t6ng nang
h1<jngcua song, cua song va cua tri~u .
Can ca van dla m~o hi~n co, tam giac chau song D6ng Nai
chill anh huang bai d 3 ye'u to' tren, nhung c6 khac bi~t doi chut tuy
tirng vi tri CI;!th€ :

- Cac lo~t gi6ng ch~y song song vai bo bi€n hi~n t~i cho
thay tam giac chilu chill lac dl;!ngcua song m~nh bon, trong vung ban
dao .C~n Th~nh.
'- Trang vung ban dao Ly Nhon, ho~t dQng cua song chi
m~nh a bo dong, nhung bi khuat a bo tay (do huang s6ng la dong nam-
lay hac; then E>~ngGong Minh va Nguy~n H11uNhan. 1993). Do d6 cac
gi6ng aday c6 khuynh huang ch~y tua tllbo song Soai R~p (di tich clla
nhung go cat song song, tuye'n tlnh hay che nhanh, n~m song song VOl
huang eua song Soai R~p), r6i sau d6 mai songsong yai bo bi€n v~ phia
song E>6ngTranh.
- A.nhhuang eua song dO'ivai tam giae eMu n~y thi qua ra
VOlcae lo~t tr~m tich long song clingnhu d~mm~ncua vung.
Moi truong rich tl;!eua song Niger du<;1eAllen phae hQa dudi
day, then chung tal, la phIl h<;1pbon d vai tam giae ehau song D6ng Nai
(hinh V.9 eua lui).nan).
V.3 Vat lieu tr~m tich:
Ngu6n eung cap vi).tli~u tr~m tich cho tam giae ehilu nfiy
tll lvu vlfc song D6ng Nai, song Be va song Saigon d~u phong pM va c1a
18
d~ng. Noi chung, chat tram rich hat ngu()n tlChai nh()m v~t li0u scln c()
la n~n da va phu sa c6 :
- V~ da tram rich, ta co da phien set, phien vC)i,phien
than, da cat, da bun; v8 da macma co granit, granodiorit, diorit, , tat
ca co kha Dang cling cap set (du lo~i tlCmontmorillonit den kaolinit va
tMm chi illit mla), bun va cat tuy thanh phan hall (1au.
- Phu sa c6 thl g6m chu yeu la cat chen voi sct va Sc.tlL
Trong mOt so tru'Cingh<;ip,s~n va set co thE chiem tJu the'.
VA Khoang vat chinh :
0 day, khong Den lam 15n khoang v~t voi kich thtJ(jc h~lt
cua chat tram tich. Khoang v~t la ban chat, kich thtJ(jc h~t la hiQn ttJ0ng.

Kich thuoc h~t khong che slf tram rich rat nhifu, tu ngu6n den noi bing
dQng, nhung suot qua trlnh bie'n d6i sau do, chinh ban cha't cua khoang
v~t mOl co anh huang quyet djnh.
Khoang v~t khong che mC)itrtJong tram tich cling co, va bj
moi traCing khong che I~i cling co. Van df quaD trQng hi~n nay la tlC
di6m Hing t~, den diEm trd thanh lOp tram rich 6n djnh hi~n nay, val tra
khoang v~t la nhu the' nao? Van df buc xuc v~ qui ho~ch la phai tiel
r6 di6m nay.
Vi d~ v~ anh htJdng cua khoang v~t doi VOlslf 6n drnh cua
n~n mong t1!nhien - tlCdo ap d~ng vao thuy 10i, xay dlfng va giao th6ng
v~n tai - la di~u dn co dap so chinh xac. Muon the', phai bier hL((jng
phan bo cua khoang v~t Ian ham ItJ0ng l~i ch6 cua chung. Ngoai fa, no
con co anh htJdng VOltinh chua, m~n, giau huu co trong tr6ng lr()l va
chao nuoi.
19
Y.5 B6i OaDcu lh6 :
Duong 00 oi6n, hay noi each khac la gi6ng, la dli kii;n kha
hung hon giup ta phvc hoi !(;Iist! phat tri6n cua tr~m tich HoJoxcn (J
Rang Sac Gia Djnh. Ta 6000 nam tra l(;liday, noi Rang Sac Gia Djnh,
co hai nhanh song chinh (D6ng Nai va Yam Co) va hai nhanh song phV
(Trang Bang va Saigon). Stf tang tntang v€;phia bi6n cua dong Dong
Nai oa lam bit nghen dong Saigon. Cling trong co du nhu vh, dong
Yam Co bit nghen dong Trang Bang. Ph\lc h6i l~n tang truang ta c6n
cat c6 cua vung, ta th3"yr6 dong Yam Co b6i nen mQt tam giac chao vt:
phia lay, huang Blnh Chanh, sail phai quay v€;nam. St! giao dong gap
nhau vao thai Tan An, tlic each nay 2000 nam (Coleman, 1972). Ta 06
de'n nay, cuOc d3"utranh khong ngang gilia hai con nuac oJ: oua oen kel
qua la t(;lOra khu vtfc Rang Sac Gia Djnh. (Hlnh Y.lO cua lu?n an). H(;I
day kie'n t(;lOM l':li d3"u 3"n Sail sac trong khu vtfc n~y, la stf bie'n mftt
(chlm m3"t) cua mOt s6 lo':lt gi6ng, chi d6 l~i r6 nh3"tlo':lt gi6ng Nhon

Tr~ch r6i 10':ltgi6ng C~n Gio.
CHuaNG YI MO HINH TRAM TICR
Sloss va Allen (1962-1964) dua ra mo hlnh tr~m tich cUa mOl
tam giac chao theo phuong trlnh nhu sail :
d':lng tr§m tich =f { Q, R, D, M }
trong 06: - Q la IU<;lngtr§m tich
- R la chuy6n oOng len xu6ng cua mong oa,
- D hi st! phan b6 ch3"ttr~m tich,
- MIa thanh ph~n khoang V?tchu ye'u.
20
Q ban g6m 3 ye'u tala ltru hi<jng cua sCmgQa, sU'ccling cClr
v~t li~u cua n0n Qb, va kha nang giu chat trJm lich uh (1,a hlnh va
tham thlfc v~t Qc :
Q = Qa + Qb + Qc
R lieu .bi~u eho slf lull day ( bi~u di6n bang R I - RO = so >0 )
ho~e nang day ( bi~udi~n bang RI - RO = so <0 ). Tni(Jng h0r>tHldc
U'ng voi giai do~n bi~n tie'n, chat tram tich t~o chi6u day; tnfi'5ng h0r>
saU,la bi~n Iui, Den chtt tram tich trd thanh mongo Ngoai ra con yell to
rb la slf Den de eua ehtt tram tich. Set va hull co rh cao. Chi so nJy ~inh
huang dQeI~p de'n R va chi tuy thuQc vao M.
D Ia ye'u to thuang bi tri6n cua cva song Dh va sU'ccan cua hili
tri6u Dm anh huang trlfe tie'p.
M d day g6m ehu yeu Ia cat, set, bun, ehtt voi. Chtt huu co do
de bi lieu huy DenkhOngdang k~Iim trong vi~ct~o d,a m~o.
Nghien CUuslf bie'n thien eua tung nhom yeti to mQttrudc va
sail khi co cac d~p tMy nong hay thuy di~n se cho chung ta thty r6 Sl/
xao trQneua moi truang tv nhien va tu do soy ra cach khie phvc. Sail
day Ia ke'tqua:
VI.l TruOc khi co daTITri An va Dau Tieng :
- Sif b6i Itp trong lam giac ChaLl Lt dang kG, VI dll lL(l,ing

trJm rich it nhung dlTQCgoi ghCm trong mOt khu vlfc nh() : cCmg Lie m,lO
vet se rtt ton kem.
- N0n 1l10ngxay dLTngl6t khCJ1lgnhi0u, da so la n0n 1l1(J1lg
lun ye'u, tru cae gi6ng d Ly Nhon, Thanh An, CJn GiG - la nhung Il(Jico
sU'ccan cua helitr[0u Om cao.
- Khoang san set g61l1chu yeu la set montmorillonite,
nhung bi nhi6m m~n Den khong th~ lam nguyen Ii~u tot cho g~ch ng6i;
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than bunco tnllU<;ingkh6ng nhi~uva chat lu<;ingkem (#25-30%C) , d t
cho xay dlfng hi~n di~n (1mOt so con song, long song.
- Slf () nhi~m ve nudc m~t rat kho giai quyet VIlricn Dh
thap, suc can cila dong tri~u Dm caD, luu lu<;ingQa khong dil va M thieu
ho<;1ttinh I~ng dQng (gom loan la v~t li~u 10hing ). VI the nen din lh~n
trong vi~c thai bi.!Gong nghi~p.
- SIf cai t~o dat d~ di VaGsan xuat nong nghi~p c1oi hoi
nhi~u kinh phi, thai gian va Gongsuc.
VI.2 Sau khi c6 daD Tri An va Dilu Tieng :
- Bien d6i dia hlnh - dia m~o : vdi Q ~ 0 va rh < 0 (d0
nen de eila v~t li~u trilmtieh), toy vdi toc dOeh~m,m~t dat se chlm d~n
xuong nude m~n. Vdi Slfnen de 0 cae tam giae chao blob thuang thl
trong yang 100 nam tdi , dia hlnh dja m~o 0 day ehua c6 thay c16igl
dang k~ ( 1-2mm/nam, Coleman 1972).
- Nude m~n theo d6 se dang eao hon ThUDue mOtchill.
SIf ho<;1tdOngeila khoi nude m~n nay se tllYthuOcvao tri~u bi~n Dm
hon la vao dong ehay Dh. Do d6, slftan ra bo se.dogi6 chuang va tri6u.
- Chat lu<;ingnude bitn d6i keG theo bien d6i trang s<1n
xuat; nong nghi~p phai du<;iethay bling hili lam nghi~p.
- Nude eho an uong sinh ho~t 0 vung n§y l<;1iphai du(}c
quaIl tam.
- N~o vet long song khong can la ganh n~ng cho dia

phuong, nhung dn tranh mQikhii nang dua den vi~e lam tan ra bo r~lch
(10ba nhan t~o do ch~tphil fling vo
ythUG,dap de ngan d~p 11fy).
- PM ho~i tham fling ng~p m~n t<;10di~u ki~n thong khi
cho cac lOp dill trang vung, cho nen vi~c I~p cac nong truang nu6i tom
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