44
4.1.4 Hydrologic condition
Upper Cimanuk Catchment Area, one of the upstream areas of Cimanuk watershed has length of 50 km length of main river. There are two discharge
gauges in this area; Bayongbong gauge which is located in the middle of the catchment and Leuwidaun gauge which is located in downstream from
Bayongbong gauge. Leuwidaun river gauge is used as outlet of catchment in SWAT simulation.
Figure 4.10 Watershed boundary of UCCA
Catchment area is derived from SRTM 30 m data by watershed delineation process. Afterward the delineation is supported by stream network which was
derived from Peta Rupa Bumi scale 1:25,000 published by Bakosurtanal. Result of watershed delineation process is shown in Figure 4.10.
River Discharge River discharge is obtained from three river gauges and direct measurement
in site. The direct measurement is aimed to compare the record from AWLR under the Public Works Department. The measurement used Current meter for water
45
velocity and river profile used theodolite instrument. The availability of discharge data is shown in Table 4.3. According to the table, Leuwidaun river gauge has
better availabile data compared to other river gauges whereas the discharge data were collected since 1970.
Table 4.3 Availability of discharge data in UCCA
No Gauge
90 ‐ 04
05 06
07 08
Qty 1
Bayongbong 1
1 1
3 2
Leuwidaun since
1970 15
1 1
1 1
19 3
Cikamiri 1
1 1
3
Figure 4.11 Monthly average discharge in Leuwidaun river gauge 1990 – 2006.
Figure 4.11 shows average of monthly discharge data series in Leuwidaun gauge. Average discharge data shows the maximum and the minimum discharge
which occurred in December 40.4 m3sec and September 6.3 m3sec, respectively.
Figure 4.12 shows daily discharge in Leuwidaun river gauge in 1971-1983 and 1993-1996, respectively. During 1971-1983 the discharge data did not show
any increment, but it occurred in 1993-1996. The condition of discharge data also is shown in Figure 4.13 where maximum and minimum data are more diverged
since 1999. The figure also presents coefficient of river regime during 1999 – 2005 which has large number.
10 20
30 40
50
Jan Feb
Mar Apr
May Jun
Jul Aug
Sep Oct
Nov Dec
Q cm
s
46
Figure 4.12 Dail
y discharges on
Le uw
id aun
st ation
g aug
e in 197
1 –
1983 and 1993-199
6 Figure 4
.13 Daily
m axim
u m
-m inimu
m disch
arges on L
euwidaun stati
o n
gaug e on
1993-199
6
20 40
60 80
100 120
Q Cms
10 20
30 40
50 60
70 80
90 1
‐Jan‐93 1
‐Mar‐93 1
‐May‐93 1
‐Jul‐93 1
‐Sep‐93 1
‐Nov‐93 1
‐Jan‐94 1
‐Mar‐94 1
‐May‐94 1
‐Jul‐94 1
‐Sep‐94 1
‐Nov‐94 1
‐Jan‐95 1
‐Mar‐95 1
‐May‐95 1
‐Jul‐95 1
‐Sep‐95 1
‐Nov‐95 1
‐Jan‐96 1
‐Mar‐96 1
‐May‐96 1
‐Jul‐96 1
‐Sep‐96 1
‐Nov‐96
Q cms
50 100
150 200
250 300
350 50
100 150
200 250
300
1971 1973
1975 1977
1979 1981
1983 1985
1987 1989
1991 1993
1995 1997
1999 2001
2003 2005
CRR Q
Cms
Qmaks Qmi
n CRR
47
4.2 Landuse Change Analyses 4.2.1 Rate of Change
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