BNPP/ASB Functional Value of Biodiversity Project – Phase II 

back to roadmap page

Model

GenRiver and SpatRain
Lead ICRAF-SEA
Collaborator NA
Scope, dataframe, spatial resolution

(complete metadata: sources, definitions, dates, resolution, etc)

 

Domain: The Mae Chaem and Sumberjaya watersheds in Southeast Asia will be compared. The two ASB benchmark areas included, with annual rainfall of about 1.5 and 2.5 m year-1 -- and thus with a total water yield (after substraction of an evapotranspiuration of 1.3 m year-1 (a fair estimate for both locations) of about 0.2 and 1.2 m year-1 -- represent the hydrology in sub humid and humid tropics. In Mae Chaem the difference between actual and potential evapotranspiration dominates the water balance via total water yield. In Sumber Jaya (Way Besai) changes in soil structure that partition total water yield over quick and slow flows are the main feature that needs to be better understood.  The rationale is that the rivers have a similar debit, but the watersheds differ markedly in population density and deforestation (land use change) history; historical rainfall and river flow records exist for both areas, while intensive studies of historical land use change have been made in the context of the Alternatives to Slash and Burn programme in Thailand and Indonesia, respectively. See Figure 7.  
study area

Mae Chaem

see Thomas et al.2003

Sumberjaya 

see Verbist et al.2003
land use cover 

(including classes distinguished) 

 Land use change (1964 - 2002)--  see Thomas et al. 2003 Land use change (1973, 1983, 2001)--  see Verbist et al. 2003
DEM  10 m resolution, see Thomas et al. 2003 5 m resolution, see Verbist et al. 2003
stream network derived from DEM, precision tests ongoing derived from DEM, precision tests ongoing
soils  using pedotransfer, see Suprayogo et al. 2003 using pedotransfer, see Suprayogo et al. 2003
streamflow data  Daily debit data from 1970 – 2000             Daily debit data Simpang Sari from 1975 – 1998
dams

 –none within catchment

none within catchment

 

Climatology 
Some of the variables to be considered under climate include rainfall, rainfall intensity, rainfall spatial correlation, and potential evaporation. A 30-year record of rainfall (defining 'climate') exist for only one station, but data for two other stations reflect similar means. Intra-station correlation of daily rainfall is, however, low, as explored by Manik et al. The station level data were used as input for the SpatRain to generate spatially explicit daily rainfall patterns consistent with station level records in their point-level exceedance probabilities, but substantially different between 'patchy', 'intermediate' and 'homogeneous' to expect different river flow patterns as a result.
variables  rainfall, basic parameters for calculating Penman potential evapotranspiration
sources  (real or simulated?)   see Manik et al. 2003
spatiotemporal resolution, original and interpolated  see Suyamto et al. 2003
time series

Climatological and hydrological Data Set for Mae Chaem

Daily debit data from 1970 – 2000           

Climatological and hydrological Data Set for Sumberjaya

1.      Daily rainfall for three stations from 1975 – 1998 (Sumberjaya, Fajar Bulan and Air Hitam)

2.       Daily rainfall for PLTA base camp station from 1996 – 1999 (half year data for 1996 & 1999)

3.       Daily relative humidity for PLTA base camp station from 1996 – 1999 (half year data for 1996 & 1999)

4.       Daily wind speed for PLTA base camp station from 1996 – 1999 (half year data for 1996 & 1999)

5.       Daily evaporation for PLTA base camp station from 1996 – 1999 (half year data for 1996 & 1999)

6.       Daily rainfall from simple rain gauge installed for erosion plot measurement in Bodong area (May – Dec 2001)

7.       Rainfall intensity (1997-1999) from Unila climate station in Sumberjaya
Machinery

A number of existing models address only a single scale, be it a plot or a catchment as a whole. Other models use a grid-cell approach with interactions between ‘cells’ leading to emergent behaviour at the catchment scale. A third category of models addresses the cross-scale questions in a more direct way by being specific on how properties change with the temporal and spatial scale of consideration.

The GenRiver and SpatRain models were first designed to answer a rather specific question: how does spatial variability of rainfall influence the ‘evenness’ of river flow that is often attributed to forests as dominant land cover? We first of all need a representation of rainfall with spatial patterns that are intermediate between uncorrelated random and fully coupled. We then need to link this to a model that includes the ‘sponge’ (forest as sponge) in its essential form, so that we can compare the relative importance of both processes. The two tools used here, SpatRain and GenRiver were developed for such a purpose.

The GenRiver model was made for data-scarce situations and is therefore based on ‘first principles’, as these may be considered the safest bet for a wide range of applications (acknowledging that directly empirical models may have greater precision within the tested range). The model includes an attempt to relate across spatial scales.

The GenRiver model was initially developed to analyse river flow in Way Besai watershed in Sumberjaya, Lampung (Indonesia), so current default input parameter are based on Sumberjaya condition. In order to make a new GenRiver application for different watershed, we need to prepare data on climate, landform, soils, geology, vegetation and land cover and actual river debit.

SpatRain is implemented with macro’s that analyze semivariance as a function of increasing distance between observation points, as a way to characterize the resulting rainfall patterns accumulated over specified lengths of time (day, week, month, year). [updated MvN 11/27/2003]

For more detail, see GenRiver background description:

http://www.worldagroforestrycentre.org/sea/upload/meine/GenRiver_SpatRain.pdf [5.2 MB]

or zip  http://www.asb.cgiar.org/BNPP/phase2/sea/genriver_spatrain.zip[1.2 MB]
Functions modeled total yield, high flows, low flows to be determined
Land cover scenarios
preindustrial forest
historical 1980 - 2000 land use change
loss of high biodiverse areas Removal ridge top forest
extensification  All shade coffee
intensification  All sun coffee
Process

(including paramaterization, validation, sensitivity tests)
parameterization for flow, infiltration, evapotranspiration, etc. Comparison with WaNuLCAS and series of run-off plts for adjusting parameters describing change in soil structure with age of the garden; see ModSim GenRiver paper
validation Validation was mainly based on frequency distribution of flows, see ModSim GenRiver paper details on inputs and processing (e.g. run by bootstrapping or off real data) - see GenRiver manual.
sensitivity analyses How sensitivity is treated in small watersheds? Single-parameter sensitivity analyses are described in the manual. We solved a problem on same-day transfers in small catchments. We solved a number of issues in the SpatRain program and believe that we can now deal with virtually any type of rainfall input data.

Further detail on the analysis of the response of watershed functions to land use change, scale and spatial pattern of rainfall (ICRAF-SEA) in the GenRiver manual.

Figure 8. Example of output of the Genriver/SpatRain analysis of the impacts of land use change on degree of buffering of riverflow relative to the rainfall pattern. The example is based on a model calibration to the situation in Sumberjaya (Lampung, Indonesia) and should be treated as a preliminary result, suggesting the type of comparisons that can be made: impacts of land use change (difference in height between three bars in each group), impacts of spatial scale (difference in height between the two groups of three bars) and interaction between scale and land use change (comparison of the two contrasts).


[updated Meine van Noordwijk 7/29/2003, m.van-noordwijk@cgiar.org ]

By September 2003, we will have made graphs like this for the following situations:
- Mae Chaem (Thailand), calibrated to local rainfall and riverflow data, with the existing land use mix in between the two extremes
- Various land use patterns for Mae Chaem derived from the scenario study 

Before the September meeting, we will also perform a ‘sensitivity analysis’ across the entire range that may be found on global maps. This will reflect
- rainfall over the spectrum 1 – 5 m year-1, using actual site-level records for 5 climate classes (A, B, C, D, E, differing in number of dry (<100 mm month-1 and wet (> 200 mm month-1) months; we can continue the analysis by regression of buffering on total annual rainfall,
- potential evaporation in the range 1 – 10 mmday-1
- landform and geology, as reflected in the daily release fraction of stored groundwater, in the range 0.003 – 0.3, so two orders of magnitude, with the current default value of 0.03 at the centre; this parameter does require inspection of river recession curves for site-specific estimates
- soils: field capacity (texture and soil depth dependent) will be varied from 70 – 700 mm, the difference between saturation and field capacity in the 20 – 200 mm range
- land use to include ‘all evergreen forest’, ‘all deciduous forest’ and a range of less-forested mosaic conditions 
Reporting and analysis of model runs

Reporting of direct hydrological flows 
grid cell or stream flow see GenRiver manual
excedance probability graphs – for what, at what locations? see GenRiver manual
matryushka diagrams? – of what, for what subbasins? Comparing ‘buffering capacity’ across space (plot, subcatchment, catchment) and time (day, week, month) for different rainfall patterns that are all consistent with the existing station records

Milestones  0, 1st, 2nd and final manuscript.
Date Expected 0 in July; 1st draft September 2003; 2nd draft 8 October 2003; final 1 December 2003.

Notes, 

Comments 

 NA.
References

.        Braak, C., 1929. The Climate of the Netherlands Indies. Koninklijk Magnetisch en Meteorologisch Observatorium te Batavia, Verhandelingen No. 8.

·        Calder, I.R., 2002. Forests and hydrological services: reconciling public and science perceptions. Land Use and Water Resources Research 2, 2.1-2.12 (www.luwrr.com)

·        Coster, C.. 1938. Naschrift: herbebossching op Java (Postscript: reforestation on Java) - Tectona 32: 602-605.

·        De Haan, J. H., 1936. Overwegingen in verband met boschreserveering (Considerations concerning forest reservation). Het Bosch 4: 1-28.

·        Gordon, N. D., T. A. McMahon, et al. (1992). Stream Hydrology: An Introduction for Ecologists. Chichester, New York, Brisbane, Toronto, Singapore, John Wiley & Sons.

·        Grove, R.H., 1995. Green Imperialism: Colonial Expansion, Tropical Island Edens and the Origins of Environmentalism, 1600-1860.. Cambridge University Press, Cambridge (UK), 540 pp

·        Heringa, P.K.. (1939). De Boschspons Theory? (The Forest Sponge Theory?) Tectona 32: 239-246.

·        Joshi et al. 2003. Soil and water movement: combining local ecological knowledge with that of modellers when scaling up from plot to landscape level. In: M. van Noordwijk, G. Cadisch and C.K. Ong (Eds.) Belowground Interactions in Tropical Agrocecosystems. CAB International, Wallingford, UK (in press).

·        Kaimuddin, 2000. Dampak perubahan iklim dan tataguna lahan terhadap keseimbangan air wilayah Sulawesi Selatan. PhD thesis, Program Pascasarjana, Institut Pertanian Bogor Kartasubrata (1981) Pre-war concepts concerning land use in Java in particular related to forest conservation. Presented at symposium on forest land use planning, Gajah Mada university, Jogyajarta. Reprinted in: Kartasubrata, J. (ed.) 2003. Social Forestry and Agroforestry in Asia, Book 2.

·        Faculty of Forestry, Bogor Asgicultural Unviversity, Bogor, Indonesia. Pp 3 – 11.

·        Kiersch, B. and Tognetti, S., 2002. Land-water linkages in rural watersheds. Land Use and Water Resources Research 2, 1.1-1.6(www.luwrr.com)

·        Ranieri S., Stirzaker, R., Suprayogo, D., Purwanto, E., de Willigen, P. and van Noordwijk, M. 2003.

·        Managing movements of water, solutes and soil: from plot to landscape scale. In: M. van Noordwijk, G. Cadisch and C.K. Ong (Eds.) Belowground Interactions in Tropical Agrocecosystems. CAB International, Wallingford, UK (in press).

·        Roessel, B.W.P. (1939). Herbebossching op Java (Reforestation on Java) – Tectona 32: 230-238.

·        Van Noordwijk, M., Van Roode, M., McCallie, E.L. and Lusiana, B., 1998. Erosion and sedimentation as multiscale, fractal processes: implications for models, experiments and the real world. In: F. Penning de Vries, F. Agus and J. Kerr (Eds.) Soil Erosion at Multiple Scales, Principles and Methods for Assessing Causes and Impacts.. CAB International, Wallingford. pp 223-253

·        Van Noordwijk, M, Farida, A., Suyamto, D., Lusiana, B. and Khasanah, N., 2003. Spatial variability of rainfall governs river flow and reduces effects of land use change at landscape scale: GenRiver and SpatRain simulations. MODSIM proceedings, Townsville (Australia) July 2003. 

.       Wulandari, R. (2002). Deteksi perubahan penutupan lahan pada areal sempadan sungai di Sumberjaya, Lampung Barat. Jurusan Konservasi Sumberdaya hutan, Fakultas Kehutanan. Bogor, Institut Pertanian Bogor and ICRAF-SEA, Bogor, Indonesia: 58.

Design and update: Sandra Velarde

                                                                                                                                               back to top

 

Global Partnership Amazon Congo Basin Southeast Asia
Climate Change Biodiversity Sustainability Poverty, Policy and Deforestation
Partners Publications Policy Briefs Gallery Funding Priorities Get Involved
e-mail: asb@cgiar.org   Home Page

 

Last updated: 01 December, 2003     ©2003 ASB. All rights reserved.