U
US SLLE E G GIIS S,, R RS S
Assessment of Arable Soil Erosion Risk in Seonakdong River Watershed using GIS, RS and USLE
*· · · 1
Jee-yeon Ko*, Jae-saeng Lee, Ki-yul Jung, Eul-soo Yun, Yeong-dae Choi, Choon-shik Kim and Bok-jin Kim1
, 1
National Institute of Crop Science, Yeongnam Agricultural Research Institute, Milyang, 627-803
1School of Biological Resource, Yeungnam University, Kyongsan, 712-749
Purpose of this study was to estimate of soil erosion, which is related with crop productivity and water quality in watershed, in Seonakdong river watershed using USLE. The data set for USLE estimation were derived from detailed digital map(K factor), satellite imagery(C and P factors) and DEM(LS factor). The R factor was calculated by AWS data from Kimhae agricultural technology center.
The soil loss from arable land was equivalent of 31.5% of total soil loss in Seonakdong river watershed.
The soil loss amount of paddy field and upland were 2.8% and 97.2% of arable land, respectively, even in the area where paddy field was occupied much largely as 76.3%. The reason of large amount of soil loss from upland was that 30.4% of upland was distributed at "severe" and "very severe" soil erosion grade in watershed. The distribution of soil erosion grade during cropping season(May-Sept.) was similar to the annual soil loss. Soil erosion of non-cropping season(Oct.-Apr.) was small due to a low R factor. But, soil erosion grade of near mountain footslope areas showed severe and very severe even in non-cropping season.
Key words : Soil erosion, USLE, GIS, RS, Seonakdong river watershed
,
(on-site effect) ,
(off-site effect) (Morgan, 1996).
,
, ,
.
.
(spatiality) (hydrology)
(spatial hydrology)
.
USLE(universal soil loss equation)
(empirical soil erosion model) Wischmeier and Smith(1965, 1978)
, : 2006. 3. 21 : 2006. 6. 5
* : Phone: +82553501267, E-mail: [email protected]
. Jung et al.(1976), Park et al.(1976) USLE
USLE RUSLE(revised universal soil loss equation)
(Jung et al., 1983; Jung et al., 1999, 2002; Park et al., 2000; Hyun et al., 2002; Jung et al., 2004, 2005).
USLE
GIS
. Kim et
al.(1994) ,
, Park(2003) 10m
. Kim et al.(2003) (DEM, digital elevation model),
, Jung et al.(2005)
.
,
USLE
, DEM
, .
(Fig. 1)
, 01,
02 ,
18 km
. 20 ,
, ,
, , 4
( , 2000).
,
,
.
USLE
(Wischmeier and Smith, 1965, 1978; Renard et al., 1996).
A = R × K × LS × C × P
A : (MT ha-1 yr-1)
R : (MJ mm ha-1 hr-1 yr-1)
Fig. 1. Location of study area.
K : (MT hr MJ-1 mm-1)
LS : ( )
C : P :
USLE 5
GIS
. (Fig. 2) USLE
, DEM, data set
.
, R
(
) AWS 2002~2005 4
. Jung et
al.(1983) (X) R
(Y=0.0378 X1.419) 7,8
(Y= 0.0453*7,8 -0.959)(Jung et al., 2002) 12 ~3
(R*1.5) .
K Wischmeier and Smith(1978)
, ,
( 1) , Box(1981)
(Km = K×(1.0977×10-0.0111x)) Jung et al.
(2004) 0-10%, 10-
35%, 35% 3
5, 22.5, 40% K (Km)
1 : 25,000
K .
K = 〔｛2.1×10-4(12-OM)M1.14+3.25(S-2)
+2.5(P-3)｝/100〕 (1)
M : (% very fine sand+% silt)×(100-% clay) S : structure code(1-4),
P: permeability code(1-6)
LS 30m DEM
Moore and Burch(1986a, 1986b)
( 2) .
LS=(al/22.13)0.4×(s/0.0896)1.3 (2)
a , l - , s
GIS
3 (Bernie,
1999).
LS=(Flow accumulation×cell size/22.13)0.4
×(sin slope/0.0896)1.3 (3)
LS Wischmeier and Smith (1965)
LS (physically based equation) DEM
Fig. 2. A database scheme for USLE evaluation in GIS.
.
C P Landsat
TM (1999.5.7 )
. Landsat TM 30m
DEM 7 band
.
program ArcView Image Analysis , Landsat TM class DN
RGB 3,4,5 band stacking ,
2 , ,
, , , , , 8
class . training
sample 15×15 m
KISAT-3 (2000. 2.9 )
. Morgan(1996)
(Oh, 1991) C P
.
ArcView 3.2
.
2002~2005
1,542 mm , R 6,460
MJ mm ha-1 (Table 1).
R (Jung et
al., 1983 ; Park et al., 2000)
R 6,290 MJ mm ha-1
(Jung et al., 1983), 6,080 MJ mm ha-1 (Park et al.,
2000) R
. Jung et
al.(2004) Jung et al.(1983), Park et al.(2000)
R 4,210 MJ mm ha-1 , R
5,496 MJ mm ha-1
. R
, 7,8
(2002~2005 7~8 : 39.0,
46.3%).
5~9 10
4
R
5,197, 1,264
MJ mm ha-1 .
K
182 . K
0.002, 0.114
MT hr MJ-1 mm-1 , K
0.025 MT hr MJ-1 mm-1 Jung et al.(2004)
K 0.027
MT hr MJ-1 mm-1 . Table 2 K , ,
, K 0.013~
0.036 MT hr MJ-1 mm-1 .
K
Fig. 3 . K 0.045 MT hr MJ-1 mm-1
, 0.33~0.45 MT hr MJ-1 mm-1
Month Jan. Feb. Mar. Apr. May June Jul. Aug. Sept. Oct. Nov. Dec. Sum
Average precipitation (mm)
R = RMi× Uadj
RMi=0.0378 Xi1.419(XiMonthly average precipitation, Jung et al., 1983), Uadj: 1.137(Jung et al., 2002), Snowy season : December-April
9.5 37.6 75.8 177.5 143.4 156.6 275.0 438.5 143.0 22.6 46.1 16.6 1,542
16 111 299 668 493 559 1,243 2,410 492 36 99 35 6,460
R factor (MJ mm ha-1)
Table 1. Monthly precipitation and R factors in Seonakdong river watershed.
K .
K fig 4
83.9% 49.0% K
0.024 MT hr MJ-1 mm-1
,
.
Table 3
. 82.4%
0~2% A slope ,
41.7% A slope , 29.1%
D slope .
DEM LS
Fig. 5 . LS
0~1 , LS
. Kim et al.(1994) Jung et al.(2005) Wischmeier and Smith(1978) McCool et al.(1987) LS
LS , DEM
Soil series
Unit of K factor is MT hr MJ-1mm-1
K factor Area
(%) Soil
code Soil
series K factor
Area (%) Soil
code Md- Mv- Sv- Sm- Sg- Sd- De- Du- St- Sb- Ss-
8.6 2.5 0.2 5.8 4.0 6.2 2.4 3.1 3.2 1.3 0.5
0.026 0.017 0.021 0.013 0.021 0.023 0.036 0.030 0.022 0.021 0.014
Taehwa
Haecheog Kimhae Bongrim Gyuam Buyong Gosan Songjeong
Jisan Jeonbug
Ta- Tr- Hc- Gh- Bm- Gy- Bg- Gx- So- Ji- Jb-
3.8 0.7 4.2 3.7 3.6 3.3 2.9 2.1 1.9 1.8 1.5
0.036 0.036 0.029 0.045 0.030 0.056 0.041 0.024 0.019 0.035 0.072 Mudeung
Samgag
Sadu Deunggu
Seogto
Table 2. Major soils and K factor in Seonakdong river watershed.
Arable
Paddy field
Upland
A: Flat, Almost flat, B: Gently slopping, C: Sloping, D: Moderately steeping, E: Steep, F: Very steep
60-100 (F) 30-60
(E) 15-30
(D) 7-15
(C) 2-7
(B) 0-2
(A)
Percent of slopeness(%) land
(ha) (%) (ha) (%)
7,658 82.4 7,804 41.7
1,023 11.0 7,316 16.4
257 12.8
247 12.8
173 11.9 288 15.0
7,184 11.9 2,554 13.2
10 0.9 17 0.9 Table 3. Arable land distribution by percent of land slope in Seonakdong river watershed.
Fig. 3. The distribution of soil K factor in Seonakdong river watershed.
Fig. 4. K factor distribution for USLE estimation of paddy and upland in Seonakdong river watershed.
30m
F
LS Kim et al.(1994) Jung et al.(2005) .
GIS Quinn et al.(1991) Desmet and Govers(1996) 2
, Woo and Hwang(1998) Foster and Whischmeier(1874)
.
LS
(Fig. 6) 94.4%, 69.2% LS 1 Hyun et al.(2002)
LS 1.72 .
Table 3 41.7%
2%
. LS 1
LS 30
K
.
C
P table 4 .
C
(5~9 ) (10~4 )
C
Lysimeter ,
, C (Jung et al.,
2004), C
Morgan(1996) .
C
, Morgan
, 0.5 ton acre-1 C
C .
P Jung et al.(2005)
P 0.5( ),
0.1( ) 1.0
, P
(Oh, 1991).
Fig. 5. The distribution of LS factor in Seonakdong river watershed.
Fig. 6. LS factor distribution for USLE estimation of paddy and upland in Seonakdong river watershed.
P factors by conservation practice in upland
- 0.25(High ridge) 0.15(Gravel band, Grass band)
0.08(Contour terrace) - - - - - 0.1
0.5
1.0 1.0 1.0 1.0 1.0 0.300
0.660
0.660 0.009 0 0 0.660 0.050
0.350
0.043 0.006 0 0 0.660 Paddy
Upland
Grass Forest Built up Vinyl house Bare soil
P factor Oct.-Apr.
May-Sep.
C factor Land use
Table 4. C and P factors used for the USLE estimation in Seonakdong river watershed.
C P
Fig. 7, 8 .
Table 5 USLE
.
31.5% ,
97.2% .
OECD
tolerable(0~6 ton ha-1 yr-1), low(6~11 ton ha-1 yr-1), moderate(11~22 ton ha-1 yr-1), high(22~33 ton ha-11 yr-1), severe(33 ton ha-1 yr-1 ) 5
, Jung et al.(2005) 7
very tolerable(0~2 ton ha-1 yr-1), tolerable(2~6 ton ha-1 yr-1), low(6~11 ton ha-1 yr-1), moderate(11~22 ton ha-1 yr-1), high(22~33 ton ha-1 yr-1), severe (33~50 ton ha-1 yr-1), very severe(50 ton ha-1 yr-1
)
(Jung et al., 2005). Fig. 9 Jung et al.(2005)
Fig. 7. The distribution of C factor from May to Sep.(a) and from Oct. to Apr. (b) in Seonakdong river watershed.
(a) (b)
Fig. 8. The distribution of P factor in Seonakdong river watershed.
Land use
Paddy Upland Vinyl house Total Total of Seonakdong river
8,727 20.2 0.4 3,594 2.8 0.9
1,787 1,624.0 61.9 124,217 97.2 30.6
838 0.0 0.0 0 0 0
11,443 - - 127,811 100 31.5
26,064 - - 406,162 100
Seonakdong river Arable
land Annual
(ton yr-1) Mean
(ton ha-1yr-1) Maximum
(ton ha-1yr-1)
Soil loss Soil loss ratio(%)
Area (ha)
Table 5. Soil loss in Seonakdong river watershed.
(Fig.
9).
very tolerable , very severe
. moderate , C
R
LS K low
.
(5~9 ) (10 ~4 )
(Fig. 10, Fig. 11) R
“ "
.
R 1/5
very tolerable
R severe very
severe .
Fig. 12
, 96.1%
very tolerable , moderate .
54.0% very
tolerable 3.7% 26.7% severe
very severe .
Table 3 Fig. 6
29.1% D slope 30.8% LS 1
, 40
. K
(Fig. 4) Hyun et al.(2002) USLE
R>LS>C P>K
, LS 3.7% 26.7%
severe very severe
. R
. Fig. 9. Soil erosion in Seonakdong river watershed.
Fig. 10. Soil erosion in Seonakdong river watershed from May to Sep.
Fig. 11. Soil erosion in Seonakdong river watershed from Oct.
to Apr.
Table 6
.
P , ,
, Morgan(1996)
10 ton ha-1 yr-1 Fig. 12. The distribution of paddy and upland classified by soil .
erosion grade in Seonakdong river watershed.
* Very tolerance: 0-2, Tolerance 2-6, Low 6-11, Moderate 11-22, High 22-33, Severe 33-50, Very severe 50< ton ha-1yr-1
Conservation practice
Contour High ridge contour Grass band, Gravel band Terrace channel
0.50 0.25 0.15 0.08
61.9 32.0 18.9 9.8
124,217 60,105 35,391 18,002 Annual(ton yr-1) Mean(ton ha-1yr-1)
Soil loss P factor
Table 6. The soil loss by the conservation practices in upland.
Fig. 13. Soil erosion by change of conservation practice in Seonakdong river watershed around Jisa stream.
< P : 0.50 > < P : 0.25 >
< P : 0.15 > < P : 0.08 >
1 ton ha-1 (Park, 1998) . Fig. 13
P .
vector “ "
.
USLE
. data set
, DEM RS GIS
, K
,
(Landsat TM) C
P , DEM
LS . R
AWS .
31.5%
, 97.5%
.
30.4%
severe very severe .
(5 ~9 ) (10 ~4 )
, ,
R 1/5
severe very severe
.
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