HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, WEST

Kasdi Subagyono1, B. Kartiwa2, H. Sosiawan2, E. Surmaini2, and E. Susanti2 1Balai Pengkajian Teknologi Pertanian Jawa Barat, Lembang-Bandung 2Balai Penelitian Agroklimat dan Hidrologi, Bogor

Abstract Hydro-meteorological processes of the Singkarak basin has been studied involving participatory of local community in 2006-2007. Automatic weather station (AWS) and automatic water level recorder (AWLR) were installed to record meteorological and hydrological data within the Singkarak Basin. Meteorological data was analyzed to understand the meteorological characteristic surrounding the Basin area. Model of GR4J and H2U were used to simulated discharge and to understand the hydrological processes within the basin. The validation of simulated discharge was done in the wet season. Best bet menu of land management options was formulated based on hydro- meteorological characteristics of the catchments surrounding Singkarak basin. The results showed that the catchments have high response to rainfall producing runoff that is discharged to the lake. The hydrograph data shows that the discharge sharply increased immediately after rainfall started then decreased quite slowly when rainfall ended. For sustainable land management in the Singkarak basin, land and water conservation have to be a priority options. Agro-forestry may be a better cropping system that has to be applied by local community. Since potential water scarcity during dry spell period may occur, water harvesting and water conservation are better options to be associated into the land management system. Keywords: Hydro-meteorology; Land management; Land use change; Singkarak basin Abstrak Study tentang karakteristik hidro-meteorologi telah dilakukan di wilayah danau Singkarak pada 2006-2007 dengan melibatkan partisipasi masyarakat. Stasion iklim otomatis dan pengukur tinggi muka air otomatis dipasang untuk memonitor data hidrologi dan meteorologi di wilayah cekungan Singkarak. Data meteorologi dianalisa untuk mengetahui karakteristik iklim di wilayah sekitar danau. Model hidrologi GR4J dan H2U diaplikasikan untuk simulasi discharge dan untuk mengkarakterisasi proses hidrologi di wilayah danau. Simulasi model aliran divalidasi pada musim hujan. Alternaf pengelolaan lahan diformulasikan berdasarkan karakteristik hidrologi daerah aliran sungai di sekitar cekungan Singkarak. Hasil penelitian menunjukkan bahwa daerah tangkapan di sekitar danau Singkarak memiliki respon yang tinggi terhadap jumlah dan intensitas hujan. Hidrograp menunjukkan peningkatan yang tajam dari discharge segera setelah curah hujan mulai dan menurun relative lamban ketika curah hujan berhenti. Untuk pengelolaan lahan secara berkelanjutan di wilayah danau Singkarak, konservasi lahan dan air harus menjadi prioritas utama. Wanatani dapat diimplementasikan sebagai alternatif sistem pertanaman oleh penduduk lokal. Karena potensi kelangkaan air bisa terjadi pada periode kering, panen air dan konservasi air dapat diterapkan sebagai opsi yang dapat dikombinasikan dalam sistem pengelolaan lahan. Kata kunci: Hidro-meteorologi; Pengelolaan lahan; Perubahan penggunaan lahan; Cekungan Singkarak

1 | HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, Kasdi Subagyono, B. Kartiwa, H. Sosiawan, E. Surmaini, and E. Susanti ISSN 1411-3082

1. INTRODUCTION gardens. Re-development of this area is their The Singkarak basin in West Sumatra main opportunity for economic development, (Figure 1) is an important rice producing area, as the area available for paddy rice fields at the basis of a large hydro-electric plant the lake side is fully utilized. Intensifying (power supply to West Sumatra and ), these coffee gardens, however, will require home to the cultural heritage of the Minang careful management of soil cover, to avoid Kabau, the second largest inland lake of negative effects on the quality of the Sumatra with endemic fish and an area of Paninggahan stream that passes by their landscape beauty and potential ecotourism village on the way to the lake. interest. Given these multiple stakeholders, To control streams flowing into the lake intensification of agriculture, both in the of Singkarak, it is urgent to monitor and irrigated rice fields and in the uplands for understand the hydro-meteorological vegetables and agro-forestry (coffee and other characteristics of the catchments surrounding tree crops) requires careful management of the Singkarak basin. Many authors have studied land and water resources, to avoid negative on rainfall-run off relationship (Pearce et al., effects on the quality of the stream that passes 1986; Tanaka et al., 1988; Burt, 1989; these areas on the way to the lake. However, Tanaka, 1992; DeWalle and Pionke, 1994; existing hydrometeorological data are Scanlon et al., 2000; Sidle et al., 2000). insufficient to parameterize existing models at Estimation of meteorological data for the the scale of refinement required. long-term water balance of a sparse vine crop A rapid hydrological appraisal (RHA) growing under semiarid conditions has also has been carried out that reviewed the various been studied by Sene (1996). Yet, those stakeholder perceptions and existing data sets, studies involving areas with lakes basin and explored the likely hydrological system are limited. consequences of a number of scenarios for The objectives of the study were to future land use in the catchment (Farida et al., analyze hydro-meteorological characteristic of 2005). To the surprise of many involved, the Singkarak basin and to conceptualize best scenarios as widely different as ‘whole bet menu of land management option for catchment covered by natural forest’ and supporting sustainable lake basin-based land ‘whole catchment degraded to grassland’ management systems. made little difference on the predicted water availability for the hydroelectric company. In 2. METHODOLOGY the model used, the additional interception Study site and water use by tree canopies balanced out The study has been conducted in the against a less buffered delivery of water to the Paninggahan sub-catchment situated in the lake which leads to overflow when the storage Singkarak basin, West Sumatra (Figure 1). capacity is reached. The model analysis, The study site lies within the upper reaches of however, was based on only scarce local data Kuantan/ basin. The site has sets and did not differentiate between the been selected by considering there was trends areas on limestone, granite or recent volcanic of loosing natural forest cover, and associated soils. with land and water management issues. A better understanding of the quantities The upper forested Paninggahan sub- of water flowing into the lake from the catchment, in particular, contain a ‘jungle different sources and the way the regularity of coffee’ enclave of several hundred hectares flow is influenced by local land use, is extent. With this site currently in process of important in enhancing the transparency of the being ‘opened up’ and ‘reclaimed’ by the allocation to the various communities of the local community via the development of an funds derived from the tax paid by the hydro- improved motorcycle track. The area was also electric company (PLTA). treated by agroforestry, with aim to explore The Paninggahan community has the dynamics of the impact of subsequent historical rights to an ‘enclave’ in the forest follow-up ‘improved’ agro-forestry reserve where the main village was located management and agricultural expansion upon before and where they still have coffee watershed functions. The catchment

2 | JURNAL METEOROLOGI DAN GEOFISIKA, Vol. 9 No.1 Juli 2008 : 65 - 77 representing the currently most hydrologically Methods stable and least degraded catchments within Hydro-meteorological data measurement the surrounding 1,130 km2 Singkarak basin The hydro-meteorological condition has been and broader Singkarak-Ombilin river basin. monitoring within the Paninggahan sub- Paninggahan sub-catchment has an area of catchment to create minimum data sets for 58.14 km2, for a primeter of 34.31 km. The sustainable land management. Since the study value of compactness index (Kc= 1.27) site has lack with hydro-meteorological indicates that the form of watershed is equipment, the catchment has been relatively rectangular, with length and width instrumented with set of automatic weather of equivalent rectangular of 12.70 and 4.58 station (AWS) and automatic water level km respectively. The drainage density of the recorder (AWLR) respectively upper (Aro Paninggahan sub-catchments is 15.08 m/ha AWS Station) and lower (Sabarang AWLR with length and width of equivalent Station) catchment. rectangular of 12.61 and 2.49 km respectively.

Geological Substrate

Soil Types

Slope

Figure 1. Digital elevation model, geological substrate, soil types and slope classes of the Singkarak basin and its 12 subcatchments as identified by Farida et al. (2005); the Paninggahan sub-catchment correspond with the northern part of subcatchment 8

3 | HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, WEST SUMATRA Kasdi Subagyono, B. Kartiwa, H. Sosiawan, E. Surmaini, and E. Susanti ISSN 1411-3082

One automatic rainfall recorders was instantaneous unit hydrograph (GIUH) installed in the upper catchment and one concept by Rodriguez-Iturbe and Valdes manual recorder was installed in the lower (1979). H2U model simulates probability catchment. Daily rainfall data has been density function (PDF) of travel time of collecting from both automatic and manual droplet from catchment to the outlet. There rainfall recorder and was compared with are two types of PDF of droplet time travel, existing rainfall data from adjacent stations. PDF of drainage network and PDF of The AWLR of sensor ultrasonic type hillslope (Kartiwa, 2004): has been installed in the Paninggahan river. n n n.V .t ⎛ n.V ⎞ 2 1 −1 − RH The rating curve to derive stream flow from ρ (t) = ⎜ RH ⎟ . .t 2 .e 2.L the water level records was conducted to RH ⎜ ⎟ ⎝ 2.L ⎠ ⎛ n ⎞ standardize the AWLR. Since no weir or Γ⎜ ⎟ 2 flume has been constructed, the wet perimeter with: ⎝ ⎠ of the stream was measured manually at high, ρRH(t) : PDF of drainage network medium and low flow rates. A minimum data n : maximum catchment order set was formulated for sustainable land VRH : stream velocity in drainage management purposes. network The AWLR provides water level and L : mean of hydraulic length of rainfall data that are stored in EPROM drainage network memory block on a 6-minute period time step. Γ : gamma function The various climate data have been collecting t : time interval from AWS including solar radiation, rainfall, Vv .t temperature, relative humidity, wind velocity V − v lo ρv (t) = .e and wind direction data on a hourly period with : l time step. The memory block of AWLR and o ρ (t) : PDF of hillslope AWS were released every 30-days period and v the data were immediately transferred in a Vv : stream velocity in hillslope computer file. The Automatic Rainfall lo : mean of hydraulic length of Recorder provided the data of rainfall on a hillslope daily period time step, which can be stored in t : time interval the memory disk having capacity of 3 months PDF of catchment can be calculated period data collection before transferring to a by : computer using CIMMET software. ρ (t) = ρ (t) ⊗ ρ (t) DAS v RH Data Analysis and Model ρDAS(t) : PDF of cathcment To support water management as part of ρv(t) : PDF of hillslope land management, river discharge has been ρRH(t) : PDF of drainage modeled. Since there were lack of discharge network data, application of discharge model is necessary in order to characterize various discharge during a year of hydrologic cycle. The infiltration index (Φ) was applied to For this purpose, an instantaneous discharge determine excess rainfall as an input model: model based on Geomorphological M Instantaneous Unit Hydrograph (H U) and a 2 Ru = ∑ (Pbm − ΦΔt) daily discharge model (GR4J) were used. m=1

H2U Model where : H2U Model (from French Ru: total observed runoff according to Hydrogramme Unitaire Universel) has been hydrograph separation analysis (mm), Pbm : developed by Professor Jean Duchesne from gross rainfall intensity to interval m (mm) Ecole Nationale Supérieure Agronomique GR4J (ENSA) Rennes, France. This model was The GR4J model is a simple, reliable, developed from geomorphological continuous lumped rainfall-runoff model at daily time step, having just four parameters 4 | JURNAL METEOROLOGI DAN GEOFISIKA, Vol. 9 No.1 Juli 2008 : 65 - 77

(Perrin, 2000]. It belongs to the family of soil than that of minimum temperature. moisture accounting models. The GR4J model Maximum temperature ranges from 20 oC to is the last modified version of the GR3J model 30 oC, while minimum temperature ranges originally proposed by Edijatno and Michel from 15 oC to 23 oC. Most of the relative (1989). Figure 2 shows a diagram of the humidity fluctuated above the value of 80 % model. with a maximum of 95%.

DAILY SOLAR RADIATION AT PANINGGAHAN SUB CATCHMENT PERIODE MARCH - MAY 2006

30.0

25.0 ) 2 20.0

15.0

10.0 Solar Radiation (MJ/m

5.0

0.0 8-Mar-06 18-Mar-06 28-Mar-06 7-Apr-06 17-Apr-06 27-Apr-06 7-May-06 17-May-06 27-May-06 Date Figure 3. Daily variation of solar radiation at Paninggahan sub-catchment during a period of March-Mei 2006

Figure. 2. Diagram of the GR4J rainfall-runoff DAILY TEMPERATURE AND RELATIVE HUMIDITY AT PANINGGAHAN SUB CATCHMENT model. PERIODE MARCH - MAY 2006 50.0 100 Formulating Best bet Menu of Land 45.0 90 Management 40.0 80 35.0 70 Based on the minimum hydro- (%) Humidity Relative C)

O 30.0 60 meteorological data sets, concept of 25.0 50 sustainable land management for restoring 20.0 40 Temperature ( Temperature watershed function was created by undertaken 15.0 30 analysis and synthesis as well as doing field 10.0 Minimum Temperature 20 Mean Temperature survey on land management practices and the 5.0 Maximum Temperature 10 Mean Relative Humidity dynamic of land use change. 0.0 0 8-Mar-06 18-Mar-06 28-Mar-06 7-Apr-06 17-Apr-06 27-Apr-06 7-May-06 17-May-06 27-May-06 Date 1. RESULTS AND DISCUSSION Figure 4. Daily temperature variation and Variation of Hydro-meteorological relative humidity at Paninggahan sub- Condition catchment during a period of March to May 2006 Meteorological condition Wind velocity ranges from 1.2 m.s-1 to 5.0 m.s-1 during a period April-May 2006 Temporal variation of daily solar (Figure 5) with mean wind velocity of 2.3 m.s- radiation during a period of March to May 1 and standard deviation of 0.8 m.s-1. Wind 2006 is depicted in Figure 3. Maximum solar direction is dominated to North West, West, radiation value was recorded as high as 26.7 and South West with total travel distance MJ.m-2 on April 17, while the minimum value during a period of April-May of 3211 km, was recorded as high as 3.6 MJ.m-2 on March 2530, and 1246 km respectively. The total 23. Average solar radiation value was 16.54 travel distance of direction of North, North MJ.m-2 with standard deviation of 5.6 MJ.m-2. East, East, South East, and South East is 3080 Temporal variation of daily temperature km. and relative humidity during a period of March to May 2006 is depicted in Figure 4. Maximum temperature was more fluctuated 5 | HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, WEST SUMATRA Kasdi Subagyono, B. Kartiwa, H. Sosiawan, E. Surmaini, and E. Susanti ISSN 1411-3082

WIND VELOCITY AND WIND DIRECTION VARIATION AT PANINGGAHAN SUB CATCHMENT 06.00 am to minimum of 59% at 11.00 am, PERIODE AVRIL - MAY 2006 10 then decreases gradually to reach 88.5% and N 3500 3000 varies about 80-90% during night. NW 2500 NE 8 2000 1500

1000 DIURNAL VARIATION OF TEMPERATURE AND HUMIDITY AT PANINGGAHAN SUB 500 CATCHMENT PERIODE AVRIL 12, 2006 6 W 0 E 35 100

90 30 4

Wind Velocity (m/s) SW SE 80

25 S 70

2 Relative Humidity (%) C)

o 60 20

50 0 15 1-Apr-06 13-Apr-06 25-Apr-06 7-May-06 19-May-06 31-May-06 40 Temperature

Date Temperature ( Relative Humidity 30 Figure 5. Daily variation of wind velocity and 10 20 variation of wind direction at Paninggahan 5 10 sub-catchment during a period of March to 0 0 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 May 2006 Time

Figure 7. Diurnal variation of temperature and Figure 6 shows diurnal variation of relative humidity at Paninggahan sub- solar radiation at Paninggahan sub catchment catchment on April 12, 2006 on April 12, 2006. Solar radiation started at -2 06.00 am with intensity of 0.05 MJ.m Hydrological Condition increasing gradually to reach the peak -2 intensity of 3.5 MJ.m at 12.00 pm, and Figure 8 shows daily discharge decreases gradually to reach minimum -2 variation of Subarang River during a period of intensity of 0.03 MJ.m at 06.00 pm. March to May 2006. During this period, DIURNAL VARIATION OF SOLAR RADIATION AT PANINGGAHAN SUB CATCHMENT 3 -1 PERIODE AVRIL 12, 2006 maximum discharge was 52.9 m s on March 4.00 23, 2006 with minimum discharge of 3.6 m3s-1 3.50 on May 30, 2006 and base flow was about 4-5 3 -1 3.00 m s . ) 2 2.50 Maximum discharge was observed

2.00 when rainfall amount at upstream (Aro AWS

1.50 Station) and downstream (Sabarang AWLR Solar Radiation (MJ/m station) reaches to 102 mm and 61.8 mm 1.00 respectively. The antecedent rainfall of a day 0.50 before was 52.6 mm and 92.6 mm - 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 respectively for Aro and Sabarang Stations. Time Other maximum discharge of 33.9 m3s-1 Figure 6. Diurnal variation of solar radiation was recorded on March 27, 2006 as a at Paninggahan sub-catchment on April 12, response of rainfall event. Rainfall was 2006 recorded as high as 13.2 mm and 20.6 mm

respectively at downstream and upstream with Figure 7 shows diurnal variation of air 1 day antecedent rainfall of 24 mm at temperature and relative humidity at Sabarang and 59 mm at Aro station. Smaller Paninggahan sub catchment on April 12, storm event were monitored also on April 14- 2006. Temperature started to increase 16, April 21-27 and April 27-29. gradually from 20.6 oC at 06.00 am to reach maximum temperature of 29.1 oC at 11.00 am, and decreases gradually to reach temperature of 21.1 oC at 05.00 pm. Temperature are relatively stable during night at about 20.0 oC. Relative humidity has an inverse pattern compared with temperature variation. It started to decrease gradually from 82% at

6 | JURNAL METEOROLOGI DAN GEOFISIKA, Vol. 9 No.1 Juli 2008 : 65 - 77

DAILY DISCHARGE OF SABARANG RIVER PERIODE OF MARCH - MAY 2006 and has given the value of similarity 100 0 coefficient of 78.9 % (Figure 10). 90 20 CALIBRATION OF DAILY DISCHARGE MODEL OF PANINGGAHAN SUB CATCHMENT PERIODE MARCH - MAY 2006 80 ARR Sabarang 40 100 0 70 ARR Aro 60 90 20 Rainfall (mm) Rainfall 60 Discharge 80 /s) 3 80 40 50 100 Rainfall 70 Observed Discharge 60 40 120

Simulated Discharge Rainfall (mm)

Discharge (m 60 80

30 140 /detik) 3 50 100 20 160 40 120 10 180

Discharge (m 30 140 0 200 9-Mar-06 19-Mar-06 29-Mar-06 8-Apr-06 18-Apr-06 28-Apr-06 8-May-06 18-May-06 28-May-06 20 160 Date 10 180 Figure 8. Daily discharge variation of 0 200 2/16/2006 3/12/2006 4/5/2006 4/29/2006 5/23/2006 6/16/2006 Sabarang River, Paninggahan sub-catchment Time during a period of March to May 2006 Figure 10. Calibration of daily discharge model, at Sabarang River, Paninggahan sub Figure 9 shows instantaneous discharge catchment, during a period of March to May of Sabarang River during a periode of March 2006 to April 2006 in 6 minutes time interval. Peak flow was observed as high as 136.02 m3s-1 at The calibration has given the 09.48 am on March 23, with minimum flow of parameters model as following: 4.18 m3s-1 at 12.42 am on March 20. Another storm event was recorded at 7.06 am on X1: Capacity of the non-linear routing March 27 with peak discharge of 132 m3s-1, reservoir 3 -1 and smaller discharge of about 25 m s on X2: Water exchange coefficient April 11, 12 and 23. X3: Capacity of the production INSTANTANEOUS DISCHARGE OF SABARANG RIVER reservoir Periode of March - Avril 2006

200 0 X4: Unit hydrograph time base

180 1 160 2 140 3

Rainfall (mm) (mm) Rainfall Application of H U in modeling of

/s) 2 3 120 4 instantaneous discharge needs an 100 5

80 6 identification of transfer function parameter Discharge (m 60 7 that must be measured from the map of 40 8 drainage network of Paninggahan sub 20 9 catchment scale 1:25.000. The characteristic 0 10 3/9/2006 3/14/2006 3/20/2006 3/26/2006 4/1/2006 4/7/2006 4/13/2006 4/18/2006 4/24/2006 of transfer function parameter of model H U 0:00 20:00 16:00 12:00 8:00 4:00 0:00 20:00 16:00 2 Time is depicted in Table 1. Figure 9. Instantaneous discharge of Sabarang River, Paninggahan sub-catchment during a Table 1. Main characteristics of transfer period of March to May 2006 function in channel network and hillslope for Paninggahan sub catchment Discharge Simulation Model Pngahan sub Parameter Unit Catchment Discharge simulation model was Channel Network developed for possible study of discharge - Mean hydraulic length (L) m 13250 characteristic as consequence of catchments - Maximum hydraulic length (Lmax) m 20050 biophysical modification. The model was - Strahler’s catchments order (n) - 5 developed based on daily and instantaneous discharge events. Hillslope - Mean hydraulic length (lo) m 331 Application of GR4J in modeling of - Maximum hydraulic length (lo max) m 1150 daily discharge of Paninggahan sub catchment has given satisfied results. The model was calibrated for a period of March – May 2006

7 | HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, WEST SUMATRA Kasdi Subagyono, B. Kartiwa, H. Sosiawan, E. Surmaini, and E. Susanti ISSN 1411-3082

Calibration of model has been applied techniques and water conservation as well as for storm event on April 11-12, 2006. The efficient water use need to be implemented. model has given very satisfied result, which is shown by the value of similarity coefficient of 2. CONCLUSIONS 96 % (Figure 11). The parameters of model 1. River flow greatly affects the dynamic that has been calibrated to obtain the behavior of water level in the lake of simulation with such as quality are: Singkarak, which influence on land • Index infiltration (Ф) to determine management in the agricultural areas excess rainfall is 0.14 mm/minutes; surrounding the lake. Data and • Time lag between peak of excess information of hydro-meteorological rainfall and peak of simulated characteristics of the basin provides discharge is 114 minutes valuable support on the planning and • Mean flow velocity for channel executing the land management. network and hillslope are 7.5 and 0.08 2. Rainfall-runoff relationship is the most m.s-1 respectively. valuable hydro-meteorological data for planning and executing land management

CALIBRATION OF INSTANTANEOUS DISCHARGE MODEL OF practices especially deals with water PANINGGAHAN SUB CATCHMENT Episode April, 11-12 2006 management. Maximum discharge was 25 0 Excess Rainfall 1 observed when rainfall amount at upstream Infiltration 20 2 Observed Discharge and downstream reaches to 102 mm and Simulated Discharge 3

Rainfall (mm) 61.8 mm respectively. The antecedent /s) 3 15 4 rainfall of a day before was 52.6 mm and 5

10 6 92.6 mm respectively for upper and lower

Discharge (m Discharge 7 catchment. 5 8 3. Hydrological condition of Singkarak basin 9

0 10 need to be monitored at different time 11/4/06 11/4/06 11/4/06 11/4/06 11/4/06 11/4/06 11/4/06 12/4/06 12/4/06 12/4/06 12/4/06 12/4/06 12/4/06 12/4/06 12/4/06 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 scale with respect to land use change for Time Figure 11. Calibration of instantaneous sustainable land management. Monitoring discharge model of Sabarang River, should be directed for different storm Paninggahan sub catchment, episode April 11- events aiming to characterize the rainfall- 12, 2006 runoff relationship. 4. The GR4J model has been proven to be an Land Management Options alternative model to simulate a daily Based on hydro-meteorological discharge event, while the H2U is characteristics, best bet menu of land applicable for simulating an instantaneous management options have been formulated. discharge event in Singkarak basin. High response of the Singkarak basin to 5. Based on hydro-meteorological data and rainfall as indicated by hydrograph data information, agro-forestry system is the suggests that land and water conservation best options of crop management. Water have to be priority options. Since land use harvesting and water conservation are the change has been a cause of land degradation approaches to cope with water scarcity due to erosion, appropriate cropping system during dry spell period. can be introduced to control the catchment and to some extend provide alternative for REFERENCES agriculture development. Agro-forestry system is the best options to achieve the goals. Agus, F., Farida and Van Noordwijk, M. Hydrological function of the catchment (Eds), 2004. Hydrological Impacts of has also changed, where rainfall can not be Forest, Agroforestry and Upland retained longer in the catchment but Cropping as a Basis for Rewarding immediately become a runoff. This means Environmental Service Providers in that during dry period, the available water for . Proceedings of a workshop irrigation is very limited. Water harvesting in Padang/Singkarak, West Sumatra,

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Indonesia. 25-28 February 2004. thesis, Université Joseph Fourier, ICRAF-SEA, Bogor, Indonesia Grenoble, 2000. Burt, T.P. 1989. Storm runoff generation in Rodriguez-Iturbe I. et Valdés. J. B., 1979. The small catchment in relation to the flood geomorphologic structure of hydrologic response of large basins. In Beven, response. Water Resour. Res. 15(5 : K.J., Carling, P. (eds.). Floods. John 1409-1420. Wiley. Chichester. Scanlon, T. M., Raffensperger, J. P. and DeWalle, D. R. and Pionke, H. B. 1994. Hornberger, G. M. 2000. Shallow Stream generation on a small subsurface storm flow in a forested agricultural catchment during autumn headwater catchment: Observations and recharge, II, Stormflow periods. J. modeling using a modified Hydrol., 163: 23-42. TOPMODEL. Water Resour. Res., 36: Duchesne J., dan Cudennec. C., 1998. H2U : 2575-2586. Une fonction de transfert pluie-débit Sene, K.J. 1996. Meteorological estimates for déterministe et polyvalente, vers des the water balance of a sparse vine crop applications multiples. Chambéry, growing in semiarid conditions. J. Journées de la société Hydrotechnique Hydrol 179: 259-280. de France, sept. 98. Sidle, RC., Tsuboyama, Y., Noguchi, S., Edijatno, and C. Michel. 1989. Un modèle Hosoda, I., Fujieda, M. and Shimizu, T. pluie-debit journalier à trois paramètre. 2000. Stormflow generation in steep La Houille Blanche. No. 2, pp. 113-120. forested headwater: a linked Farida, Kevin Jeanes, Dian Kurniasari, Atiek hydrogeomorphic paradigm. Hydrol. Widayanti, Andree Ekadinata, Danan Process., 14: 369-385. Prasetyo Hadi, Laxman Joshi, Desi Tanaka, T., Yasuhara, M., Sakai, H. and Suyamto, and Meine van Noordwijk. Marui, A. 1988. The Hachioji 2005. Rapid Hydrological Appraisal experimental basin study-Storm runoff (RHA) of Singkarak Lake in the processes and the mechanism of its Context of Rewarding Upland Poor for generation. J. Hydrol., 102: 139-164. Environmental Services (RUPES). Tanaka,T. 1992. Storm runoff processes in a Working Paper. small forested drainage basin. Environ Kartiwa, B. 2004. Modelisation du Geol. Water Sci. 19, no. 3: 179-191. fonctionnement hydrologique des basins Tomich, T.P., van Noordwijk, M. and David versants, application sur des bassins E.Thomas,D.E.,2004. Environmental versants de Java et Sumatra. These de services and land use change in doctorat. Universite d’Angers. Southeast Asia: from recognition to France.197 pp. regulation or reward? Agriculture, Pearce, A. J., Stewart, M. K. and Sklash, M. Ecosystems and Environment 104: 229- G. 1986. Storm runoff generation in 244 humid headwater catchments, 1. where Van Noordwijk, M., 2005. RUPES typology does the water come from?. Water of environmental service worthy of Resour. Res., 22: 1263-1272. reward. RUPES working paper, Perrin, C. Towards an improvement of a ICRAF-Southeast Asia, Bogor. 53 pp lumped rainfall-runoff model through a comparative approach (in french). Ph.D

9 | HYDRO-METEOROLOGICAL CHARACTERISTICS FOR SUSTAINABLE LAND MANAGEMENT IN THE SINGKARAK BASIN, WEST SUMATRA Kasdi Subagyono, B. Kartiwa, H. Sosiawan, E. Surmaini, and E. Susanti