Application of the SHE to catchments in India Part 1. General results

Journal of Hydrology, 140 (1992) 1-23 Elsevier Science Publishers B.V., Amsterdam

1

[4]

Application of the SHE to catchments in India Part 1. General results J.C. R e f s g a a r & * , S . M . Seth b**, J.C. B a t h u r s t c, M. E r l i c h J, B. S t o r m ~, G . H . J o r g e n s e n " a n d S. C h a n d r a b***

"Danish ttydraulic Institute, Agern AIId 5, DK-2970 Horsholm, Denmark hNational Institute of Hydrology, Jal Vigyan Bhanan, Roorkee 247 667, Uttar Pradesh, India ~NERC Water Resource Systems Research Unit, Department of Civil Engineering, University of Newcastle-upon- Tyne, Newcastle-upon- Tyne NEI 7RU, UK dLaboratoire d'ttydraulique de France, 6 Rue de Lorraine, 38130 Echirolles, France (Received 14 January 1992: revision accepted 19 June 1992)

ABSTRACT Refsgaard, J.C., Seth, S.M., Bathurst, J.C., Erlich, M., Storm, B., Jorgensen, G.H. and Chandra, S., 1992. Application of the SHE to catchments in India. Part 1. General results. J. Hydrol., 140: 1-23. The ~Systeme Hydrologique Europ~en' (SHE) modelling system has been applied to six subcatchments totalling approximately 15 000 km 2 of the Narmada Basin in Madhya Pradesh, central India. The study was carried out within the framework of an Indo-European cooperative project aimed at a transfer of the SHE technology to the National Institute of Hydrology, India. This paper presents the current status of the SH E, and then focuses on the experiences gained in applying it to basins of a size likely to be of practical interest, with a data availability characteristic of developing countries. Results from the largest of the six basins are presented and discussed along with summary results from all six basins. The procedures adopted and practical recommendations are given with regard to data collection, model preparation and parameter assessment, calibration approach and planning of field investigations. Finally, general conclusions regarding SHE applicability to Indian hydrological conditions are presented.

INTRODUCTION

Large-scale water resources development projects are widespread within India. The irrigation projects are often carried out within the framework of comprehensive basin development projects aimed at increasing food and energy production for the rapidly growing population. The scarcity of water Correspondence to: J.C. Refsgaard, Danish Hydraulic Institute, Agern All6 5, DK-2970 Horsholm, Denmark. * Project Manager on behalf of A S H E organizations. **Project Coordinator, National Institute of Hydrology. *** Project Director, National Institute of Hydrology.

0022-1694/92/$05.00

(~), 1992

Elsevier Science Publishers B.V. All rights reserved

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J.C. REFSGAARI) ET AL.

due to the erratic nature of the monsoon, which is a reality in several Indian states, calls for an efficient use of the available water resources. Implementation of water resources development projects may have significant effects on the hydrological regime. The most important effect is often due to changes in land use (deforestation, afforestation, land reclamation, introduction of new cropping patterns~ etc.), which are often associated with irrigation projects. Changes in land use may have significant effects on the runoffcharacteristics of a catchment, particularly on floods, annual yield, and sediment load. These effects are to some extent qualitatively known: however, the quantitative effect of land use changes on the hydrological regime has not yet been established. Another important issue in connection with water resources development projects is the effect of irrigation on the hydrological regime in command areas (i.e. the area to which irrigation water is supplied). Irrigation may, in some cases, cause a rise in groundwater table which may result in water logging and increased salinity in the soil water. In general, prediction of the responses of hydrological systems are made by simulation models. Numerous hydrological models have been developed in the past, but traditional models are largely 'lumped', i.e. they refer to the spatially averaged condition of the entire basin. Furthermore, their parameters have no direct physical meaning and cannot easily be derived from measurable properties of the basin. In these circumstances traditional models can be applied only as long as the river basin remains unchanged. Therefore, they cannot be used to predict the effects of changes in land use, such as deforestation, recultivation or irrigation. To solve such problems, a more sophisticated approach to hydrological modelling is needed. (1) The model must be spatially distributed to allow the reflection of changes in different parts of the basin. (2) The model components must be based on basic physical laws to permit extrapolation beyond the range of the data used for calibration. (3) Model parameters should be such that they can be evaluated by direct measurement, to enable the effects of future alterion of states to be simulated, e.g. for land use change studies. Only a few models of this kind have been reported in the literature. One of the major developments is the 'Syst~me Hydrologique Europ~en' (SHE). The SHE has been developed jointly by the Danish Hydraulic Institute (Denmark), Institute of Hydrology (UK) and SOGREAH (France), organized in the ASHE group (Association pour le SHE). The development

APPLICATION OE SHE TO INDIAN CATCHMENTS

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was partially supported by the Commission of the European Communities (CEC) and by national research funds (Abbott et al., 1986a). The present paper describes results from a 3 year Indo-European project based on an agreement between the CEC and the Government of India signed in July 1987. The project was executed by the National Institute of Hydrology (NIH), Roorkee, India, with the assistance of a group of consultants headed by the Danish Hydraulic Institute and composed also of SOGREAH (France) and the University of Newcastle-upon-Tyne (UK). The overall objective of the cooperation was to transfer the SHE, including the necessary mathematical modelling know-how and computational expertise, to NIH in order to enhance India's capability for fomulating water and land resources development strategies through numerical modelling. Within the project, the SHE has been applied to six subbasins of the Narmada River in Madhya Pradesh, and studies have been carried out on the hydrological effects of land use change and on soil moisture conditions in irrigation command areas. The basins are larger and have a rather limited data coverage compared with previous applications, which have tended to be on small research catchments, (e.g. Bathurst, 1986). This paper presents the current status of the SHE, and focuses on the experiences gained in applying it to basins of a size likely to be of practical interest, with a data availability characteristic of developing countries. Results from one of the six basins (the largest) are presented and discussed along with summary results from all six basins. Detailed results from the smallest basin are presented in the accompanying paper by Jain et al. (1993), and results from the irrigation command area studies are described in Lohani et al. (1992). Detailed project results are reported in National Institute of Hydrology (NIH) (1991) and a series of NIH reports. C U R R E N T STATUS OF THE SHE

The SHE is a generalized mathematical modelling system capable of describing the entire land phase of the hydrological cycle in a basin in any geographical area. The basin is discretized in the horizontal by two identical grid square networks, for overland flow and groundwater flow. These are linked by a vertical column of nodes at each grid point to represent the unsaturated zone (Fig. 1). The spatial distributions of the basin properties and the meteorological inputs are represented by assigning parameter and data values at each grid square and node point in the network. Water movements in the basin are modelled by a numerical solution (finite difference) of the partial differential equations describing the processes of overland and channel

4

J.C. REFSGAARD ET AL.

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flow, unsaturated and saturated subsurface flow (including stream/aquifer interaction), interception, evapotranspiration and snowmelt. Development of the SHE, initiated in 1976, is described by Abbott et al. (1986a), while a description of the SHE structure and its process representation is given in Abbott et al. (1986b). An example of an application of the initial (1982) version of the SHE to a small research basin is described in Bathurst (1986). The three ASHE organizations, with whom the proprietary right and the development experience lie, are now the Danish Hydraulic Institute, the University of Newcastle-upon-Tyne (UK) and the Laboratoire d'Hydraulique de France. The organizational responsibilities in the UK and France have been transferred from the initial developing organizations together with the associated key persons. Significant further developments have been carried out over the past 6 years by the three ASHE partners. Some of the important developments in improved description of processes and data processing programs have taken place in interaction with Indian scientists under the Indo-European project. Progress has been made on the following lines. (1) Comprehensive preprocessor and postprocessor program packages have been developed, enabling efficient data manipulation and graphical

APPLICATION OF SHE TO I N D I A N C A T C H M E N T S

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5

presentation of input data and simulation results. This development was necessary for modelling basins with a size of practical interest. (2) Improved description of some of the processes. Thus, the following phenomena can now (optionally) be accounted for: subsurface pipe drainage flow; surface retention; macropore/soil crack flow as bypass to porous media flow; lakes; hydraulic structures (e.g. dams) in river system; three-dimensional and multilayered aquifer systems; enhanced river-aquifer interaction; surface irrigation. Further details are given in Engesgaard and Jensen (1990), Storm (1991), Aboujaoud6 et al. (1991) and Lohani et al. (1992). (3) Development of add-on modules for transport-dispersion, water quality, soil erosion, crusted soil infiltration, etc. Further details are given in Ammentorp et al. (1986), Storm and Jorgensen (1987), Wicks et al. (1988), Styczen and Nielsen (1989), Aboujaoud6 (1991), Bathurst and Purnama (1991), Refsgaard et al. (1991), Storm et al. (1991) and Wicks and Bathurst (1992). (4) Application of the SHE to several projects, Storm and Jorgensen (1987), Engesgaard and Jensen (1990), Refsgaard and Jorgensen (1990), Bathurst and Purnama (1991), Jensen et al. (1991), Storm et al. (1991), Villholth et al. (1991), Bathurst and Cooley (1992) and Wicks et al. (1992). Some of these developments have taken place as common activities involving all three ASHE partners; others have been carried out by only one of these organizations. SELECTED BASINS OF THE RIVER NARMADA AND DATA AVAILABILITY

Application of the SHE to selected basins in India formed a major component of the project. The Narmada Basin was chosen for the tests, since it is undergoing large-scale water resource development. Furthermore, NIH had already carried out flood studies in the area and had good links with the Madhya Pradesh Irrigation Department (MPID), which has a major interest in the Narmada system. The Narmada is the major west-flowing river in Central India, linking the States of Madhya Pradesh, Gujarat and Maharashtra and having a total catchment area of 99 000 km 2. For the case studies, six of its tributary basins in Madhya Pradesh were chosen on the basis of data availability and the conclusions of an initial field visit (Fig. 2). Average annual rainfall in the focus area is around 1200 ram, with the southwest monsoon accounting for 90% of this figure and 60% falling during the months of July and August. Soil surveys indicate that much of the area consists of a variety of black cotton soil with a large clay content. Mixed red and black soils, red and yellow soils and

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skeletal soils are observed in isolated areas. The soils are generally deep in the plain areas along the Narmada River, whereas shallow soils, less than 1 m deep, are found in the upland catchment areas of the tributaries. The basin areas and key figures on basin characteristics and data availability are presented in Table I. As there are no central hydrological data archives in India, many different agencies had to be approached for the data collection. During this process it was discovered that a considerable amount of useful data and experience could be drawn from a wide range of agencies, several of which might not immediately come to mind in connection with conventional hydrological and water resource studies. Altogether, some 15 agencies representing meteorological, irrigation, agricultural, geological and other professional fields in government, universities and research institutions were approached during the project (Table 2). The following general conclusions have been drawn with regard to data availability. (1) Rainfall. Not all the raingauge stations indicated in Table 1 lie within the basins, and spatial coverage with continuously recording raingauges giving hourly rainfall is especially poor. Only the Kolar is well represented in this respect. For the other basins, the daily rainfall records were distributed on an hourly basis according to the pattern measured at the nearest recording gauge. Usually only one such gauge was available for each basin, often lying either close to the boundary or outside the basin. Correlation between the rainfall patterns throughout the basins, especially the larger ones, is by no means assured so this method of distributing rainfall temporally, although the best available, is a considerable source of uncertainty. This uncertainty is further aggravated by the uneven spatial distribution of gauges (upland areas are poorly represented) and by the infilling necessary to close gaps in the measured time series. (2) Discharge. Reliable data are available only at the basin outlets: discharge is measured once in a day during monsoon seasons using a velocity area method and water levels are observed every hour. When the river is too high for current metering to be carried out, float gauging is sometimes used, with the velocity coefficient calibrated from measurements at lower flows. For this project, separate stage-discharge records were compiled for each monsoon (or two groups of monsoon in the case of the Kolar) and used to convert the measured stage values to discharges. (3) Evaporation. Data are sparse. Each basin has only one pan evaporation station, located either at the boundary or outside the basin. Evaporation tends to be more spatially uniform than does rainfall (at least over periods of

8

J.C. REFSGAARD ET AL.

1 week or more) but even so, it is likely that the spatial lumping involves some error. The provision of hourly evaporation rates from the daily, weekly and monthly records also involves considerable temporal lumping. (4) Topography. In all cases, land and channel elevations were taken from 1:50 000 scale contour maps. (5) Land use. Maps at the scale of 1:250 000 are being prepared by the Narmada Valley Development Authority but are currently available only to the west of longitude 80°E. This region covers all the basins except half the Hiran and all the Narmada (Manot). For the Hiran east of 80°E, land use was taken from the 1:50 000 topographic maps. For the Narmada (Manot) land use was taken from satellite imagery and the 1:50 000 topographic maps. (6) Soil distribution. Maps are available as for land use. For the Hiran east of 80°E and the Narmada (Manot) the distributions were obtained from 1:2 000 000 scale maps in the Agricultural Atlas of India. (7) Soil and vegetation properties. There is a general lack of direct information on soil and vegetation properties, root zone depths, vegetation growth and cropping patterns, soil depths, soil moisture and aquifer properties. The partial exception is the Hiram for which measurements of soil properties and soil depths at specific locations are available in reports by the Madhya Pradesh Soil Survey (1974), Kaushal (1981) and Kauraw (1982). All other information has been obtained indirectly from reports and papers on neighbouring areas or by standard hydrological derivations (Hodnett and Bell, 1981, 1986; Sutcliffe et al., 1981; Kauraw, 1982; Madhya Pradesh Agricultural Department, 1986; Sutcliffe and Green, 1986; Gupta and Varade, 1988). (8) Channel cross-section. Cross-sectional dimensions are generally available at the basin outlets only. However, during a field visit to the Hiran Basin in May 1989, a series of rough cross-sectional surveys was made along the mainstem during a single day, the data from which were subsequently used to derive the relationships (shown in Fig. 3) between channel dimensions and upstream channel length measured on a 1:250 000 scale map. Tested against the outlet channel dimensions for the Narmada (at Manot) and Ganjal basins, the Hiran relationships are seen to apply reasonably well. These relationships were therefore used to provide cross-sectional data as required throughout the Hiram Ganjal and Narmada (Manot) systems. Field investigations were carried out in the Kolar Basin during a 2.5 week period in January 1990 to derive soil and vegetation parameters (see Part 2 of this paper, Jain et al. (1993)). APPROACH FOR M O D E L SET-UP

Model set-up is the process of preparing the data in the correct format and

1

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Reference

b O u t o f t h e s e t h r e e s t a t i o n s , o n e is l o c a t e d 10 k m o u t s i d e t h e c a t c h m e n t a n d a n o t h e r w a s o n l y r e p o r t i n g a f t e r 1985. c F o r c a l i b r a t i o n a n d v a l i d a t i o n p u r p o s e s s i m u l a t i o n o f inflow to Bari R e s e r v o i r ( c a t c h m e n t a r e a 1176 k m 2) h a s b e e n u s e d . d O u t o f t h e s e f o u r s t a t i o n s , o n e is l o c a t e d 10 k m o u t s i d e a n d a n o t h e r 20 k m o u t s i d e t h e c a t c h m e n t . L o c a t e d 20 k m o u t s i d e t h e c a t c h m e n t .

3b 3 4d 5 7

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and key characteristics

L o c a t e d 70 k m o u t s i d e t h e c a t c h m e n t .

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TABLE 2 List of agencies contacted during data assembly (I)

(2)

(3) (4) (5) (6) (7) (8) (9) (10) (1 I) (12) (13) (14) (15)

Madhya Pradesh Irrigation Department (a) Director, Hydrometeorology (b) Upper Narmada Circle (c) Superintending Geologist (d) Various concerned circles, divisions and subdivisions Narmada Valley Development Authority, Bhopal, MP (a) Superintending Engineer, Circle 2 (b) Joint Director (Agriculture) Central Water Commission JNKVV Agricultural University, Jabalpur, MP India Meteorological Department, Delhi, Pune, Nagpur and Bhopal Central Ground Water Board, North Central Region Survey of India, Dehradun, UP Narmada Control Authority, Delhi and Bhopal All India Soil and Landuse Survey Organisation, New Delhi and Nagpur Director, Department of Agriculture, Bhopal and Zonal Agricultural Research Stations at Powerkheda, Khandwa and Adhartal Madhya Pradesh Groundwater Survey Board, Bhopal and other offices State Forest Research Institute, Jabalpur, MP College of Agriculture, Indore Institute of Deciduous Forest, Jabalpur, MP Officesof Statistics and Land Records in relevant districts

entering them into the S H E d a t a files, which represent the c a t c h m e n t characteristics. The following a p p r o a c h was used in processing and model set-up for the six basins. (1) D a t a on t o p o g r a p h y , river network, soil type and land use were read f r o m m a p s using a digitizer and t r a n s f o r m e d into discretized representations at the model grid scale. Initially, the digitized data were superimposed on a basic c o m p u t a t i o n a l grid n e t w o r k of 500 m x 500 m (1 k m x 1 km for the N a r m a d a above M a n o t ) . However, in view of the heavy c o m p u t i n g requirements associated with such a densely defined network, the basic array was converted to one with grid squares o f 1 k m x 1 km, 2 km x 2 km and in some cases 4 km x 4 kin. These conversions were m a d e with very little m a n u a l effort as a result of facilities available in the S H E preprocessor programs. The calibrations for all basins were m a d e with grid squares of 2 k m x 2 kin. (2) A n intensive field survey of all basins was not feasible and model parameters and their spatial variations were, therefore, evaluated from the

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Fig. 3, Channel dimension relationships based on data of the Hiran Basin. Map river length is measured on a 1:250000 scale map. SHE river length is measured along the model orthogonal grid representation of the river system. available information, mostly obtained indirectly from the literature on neighbouring areas, discussions with local staff and qualitative field observations. Generally four basic land covers were identified as agriculture, open forest, dense forest and waste land, and then further divided between lowland, hillslope and upland areas. Soil depths were assumed to vary according to the same pattern, being deep (7-15 m) in the lowland areas, and rather shallower elsewhere (0.2-6 m). Two soil types were generally applied in the vertical, the

12

J.C. R E F S G A A R D ET AL.

upper layer being less permeable than the lower. Both for convenience and because of a lack of information, the initial estimates of the soil parameters were the same for all basins except the Hiran, for which specific field measurements were available (Madhya Pradesh Soil Survey, 1974; Kaushal, 1981; Kauraw, 1982). Similarly, the same soil retention curve, typical of black cotton clays, was used throughout. Vegetation properties and growth patterns were kept the same for each vegetation type in the six basins. For want of information, the overland flow resistance coefficient was assumed to be spatially uniform in each basin. The channel flow resistance coefficient was evaluated using measured flow and channel data at the basin outlets. Spatial variation in channel geometry for the Ganjal, Hiran and Narmada (Manot) basins was evaluated on the basis of a brief field survey (Fig. 3). (3) Information about basin response mechanisms was obtained from previous studies in the region (e.g. Hodnett and Bell, 1981, 1986; Sutcliffe et al., 1981; Sutcliffe and Green, 1986). For the lowland agricultural areas with deep soils, the initial monsoon rains are absorbed by the soil moisture reservoir, with cracks playing an important role in enhancing infiltration. Once this reservoir is full and the cracks have sealed, further rainfall is lost as surface runoff, interflow in the upper layers of the profile or evaporation. During the dry season, moisture in the root zone is lost through evapotranspiration while the deeper groundwater reservoir drains slowly, contributing to deep storage or river baseflow. Less is known about the hydrology of the upland areas with shallow soils. However, runoffis likely to be relatively rapid because of the thin soils, steep slopes and greater prevalence of small channels. In the flat agricultural areas, the field bunds impound the surface runoff, impeding its progress to the main river channels. The construction of the fields and field bunds also appears to obliterate any small channels, further hindering surface drainage. (4) With the model data sets established, initial test runs were carried out using hypothetical input data to check for errors in the set-up. With these eliminated, the way was open to make simulations based fully on the measured data and evaluated parameters.

CALIBRATION PROCEDURE A physically based model has the potential to estimate parameter values by field measurements without having to carry out parameter optimization as required by the simpler hydrological models of the lumped, conceptual type. However, such an ideal situation requires comprehensive field data covering

APPLICATION O F SHE TO I N D I A N C A T C H M E N T S

I

13

all parameters and a model discretization to an appropriate scale. It is evident from the previous description of the selected basins of the River Narmada that the data availability for the present case studies is not sufficient for this purpose, and that the model discretization is too coarse to resolve all the processes with a fully physically correct description. Therefore, parameter optimization was included in the calibration procedure. When carrying out parameter optimization for physically based models it is important to realize that this cannot be done by free optimization of all parameters as is usually done in the case of the simpler models. Owing to the physical character of the individual parameters they can only be allowed to vary within realistic ranges reflecting the field data information, and the more field data that exist the more narrow these ranges become. Thus, by allowing free optimization a physically based model might degenerate to a conceptual model, with just the disadvantage of containing too many parameters. The calibration procedure used here, and a description of how the field data information was utilized, is presented in detail for one of the case studies in the accompanying paper (,lain et al., 1992). In general, the procedure used for all the six basins was: (1) A split sample test was defined by dividing the available time series record into two parts. Calibration was carried out using the first period covering two or three successive monsoon seasons and the intervening dry seasons. Validation was then performed for the following period of the same length. Each simulation period began by 1 May, and the initial phreatic surface levels were, therefore, defined from consideration of premonsoon well levels. (As these were relevant mainly to the lowland agricultural areas, levels for the upland areas were estimated as a function of soil depth.) (2) The basis of the calibration was comparisons between simulated and observed monthly outlet hydrograph volumes, outlet peak discharges and outlet baseflow discharges. Some calibration against phreatic surface elevations at well sites was also possible in a more qualitative sense. (3) Calibration proceeded by adjusting a few key parameters found from experience to have particular effects on the simulated hydrographs. Thus, the Strickler resistance coefficients for overland and channel flow were used principally to calibrate hydrograph peaks, the saturated conductivity for the unsaturated zone determined the amount of infiltration and thence the runoff hydrograph volume, the saturated zone conductivity affected baseflow discharges, while the soil crack and surface detention submodels were used to moderate the amount of infiltration and runoff in the early stages of the monsoon. In general, adjustments to parameter values were kept within physically realistic limits.

14

J.C. REFSGAARD

ET AL.

I_Narmada uptoHanot1984

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In this section, the model results are illustrated by a few key results from the largest basin, the Narmada above Manot, and results from all the six basins are shown in a summarized form. For further details, reference is made to Jain et al. (1993) for the Kolar Basin, and to the six NIH reports indicated in Table 1. A more detailed discussion of the simulation results and their physical realism is given in Jain et al. (1993). Figures 4 and 5 show a comparison of the simulated, and the observed, hydrographs for the Narmada (Manot) catchment during the calibration and validation periods, respectively. For all the six catchments, a comparison of the measured and simulated monthly runoff volumes for the five months June-October is shown in Fig. 6 for both the calibration and the validation periods. Finally, a plot of the simulated annual peak discharges versus the measured values is given in Fig. 7. For the Narmada (Manot) catchment, the figures show that the observed

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5IDULafED

1985 Fig. 5. Observed and simulated hydrographs for the Narmada at Manot during the validation period 1985 and 1987.

and the simulated hydrographs match reasonably well. The baseflows and the small peaks at the beginning of the monsoon are generally less well simulated than the remaining part of the hydrographs. The validation results show a better simulation of peak discharges but a poorer simulation of the monthly runoff volumes as compared with the calibration results. From the summary of all six basins (Figs. 6 and 7) it can be seen that, except for the Sher catchment, the results are of a similar goodness and do not indicate any general difference in goodness between the validation and the calibration periods. The relatively poorer results from the Sher Basin may be due to the very poor rainfall data availability in this basin (Table 1). The modelling results are considered satisfactory taking the general data availability and quality into account. Two key conclusions, which have been derived from the studies, may be emphasized here. (1) The main source of uncertainty with regard to runoff simulations is the limited amount of rainfall data. The uncertainty in the basin rainfall input data is generating an uncertainty in the simulated runoff, which cannot be reduced by collection of other field data. Thus, the uncertainty due to incomplete rainfall data may be considered a lower uncertainty level for the simulated runoff. (2) The rainfall-runoff simulation results are of the same degree of accuracy as would have been expected with simpler hydrological models of the lumped, conceptual type. Thus, the present results do not justify the appli-

16

].C. REFSGAARD ET AL CALIBRATION 800

~ =

600

,2" 'z

/

t

/

/" "

•

/

400 _

,,

o

•

KOLAR

A

SHER

!

o

BARNA

[

•

GANJAL

o

HIRAN

•

NARMADA

,,

KOLAR

A

SHER

z D

/

,m

.•

g =

200

&&

I

•

rm

J

/

°a,.--o --

•

I

n

/[ ]

.

.÷ & o _,~^. ~"

a

I

i 200

0

i

i

I

ao0

OBSER~D

RUNOFF

I 600

800

(mm/'monEh)

VALIDATIO N 800

/

/

3

600 _

=

--

0

./

/

4.00

"'

z

/

D

0

:i:

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•

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/

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o/

o

1

~ 200 OBSERVED

i

F

I 400

RUNOFF

i

I 600

I

q 800

(mm/month)

Fig. 6. S i m u l a t e d m o n t h l y m o n s o o n ( J u n e - O c t o b e r ) r u n o f f c o m p a r e d with m e a s u r e d values for the c a l i b r a t i o n a n d v a l i d a t i o n periods. Results are f r o m all six c a t c h m e n t s .

APPLICATION OF SHE TO INDIAN CATCHMENTS

1

17

CALIBRATION 8000

6000

,I

J

"/ "

".n

// /

4000

,/

Z

/

z<

m

•

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•

/ /

~n

=<

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~

2ooo_ ,

./

"~

/-

/

/ I

I

0

C~ANJAL HIRAN

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•

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A• A

~ o

•

I

0

I

I

2000

T

F

~.000

~

6000

8000

ANNUALP E A K (rn3,/s)

OBSERVED

VALIDATION 8000

6000 v y

//

J

/

II/

L

<

i

/

:

B

4-000

O

Z Z

,"

<

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2000

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1

2000

4000

1

1 6000

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i 8000

OBSERVED ANNUALPEAK ( m 3 / s ) Fig. 7. Simulatedannual peak dischargescompared with measured values for the calibration and validation periods. Results are from all six catchments.

18

J.C. REFSGAARD ET A L

cation of an advanced model as SHE in cases where the modelling objective is limited to rainfall-runoff modelling, and where observed runoff records exist for calibration purposes. However, in addition to the runoff simulations, the SHE modelling provides detailed simulations of the various hydrological processes within the catchment by use of all existing data on topography, soil, vegetation, geology, meteorology, etc. It is realized that SHE modelling using 2 km × 2 km grid squares does not provide a fully physically based, and fully distributed, description of the hydrological regime. For instance, the real river channel network is too dense to be accurately resolved in such a coarse discretization and many of the smallest (highest order) channels could not be included in the model representation. This simplification has the following effects, amongst others, on the SHE process representation. (1) The surface water, which in the basin runs as overland flow over a relatively short distance until it joins a river channel, will in the present model representation be routed as overland flow over a relatively longer distance until it joins one of the lower order streams. Thus, what in reality should be channel routing is in the model represented as overland flow routing, implying that the overland flow resistance coefficient is not fully physically based but has to be estimated through calibration. With the calibrated resistance coefficients, the model provides good results, because the kinetics of overland flow and channel flow are, basically, the same. (2) In the simulation, the groundwater draining to the river channels as baseflow has to travel over a longer distance, because the river network is less dense in the model. Therefore, the simulated phreatic surface gradients are not fully correct, implying that the estimation of the hydraulic conductivity through calibration will somehow compensate for this. Like the above overland flow case, this has no effect on the quality of the simulated outlet hydrograph, because the basic dynamics (in this case linear) are preserved, but the parameter values cannot be taken directly from point field measurements, and the simulated phreatic surface elevations within the 2 km × 2 km grid cannot be assumed to be fully correct. Some researchers have, in recent years, argued that there are fundamental problems in the application of physically based models for practical prediction in hydrology. For instance Beven (1989) suggests that, in most current applications, physically based models are used as lumped, conceptual models at the grid scale. As may be apparent from the above discussion, the present authors agree that some degree of lumping and conceptualization has taken place at the grid scale of the present model application, with the result that some (few) model parameters have to be assessed through calibration,

APPLICATION O F SHE TO I N D I A N C A T C H M E N T S

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19

and that a direct comparison between simulated variables at a 2 km x 2 km grid, and the same variables measured at a point scale in the basin may have little meaning. Thus we agree with Beven (1989) that scale problems are important and that there is a considerable need for further research on fundamental problems like heterogeneity of parameters and variables and subgrid scale integration. However, we should like to stress that in spite of the above comments, the present basin model is much more physically based and distributed than the traditional lumped, conceptual model, where the entire catchment is represented in effect by one grid square, and where the process representations due to averaging over characteristics of topography, soil type and vegetation type are fundamentally different from the basic physical laws. Therefore, we are convinced that, although the present catchment representation may not be sufficiently detailed for some modelling purposes, such as soil erosion or stream-aquifer interaction studies, it is still well suited for other modelling studies, such as the prediction of the effects of land use changes, for which no real alternative to a physically based, distributed modelling approach exists. CONCLUSIONS R E G A R D I N G SHE APPLICABILITY TO INDIAN HYDROLOGICAL CONDITIONS

On the basis of the experience gained from the SHE studies of the six Narmada subbasins and the irrigation command area study (Lohani et al., 1992), the following main conclusions have been drawn regarding the applicability of SHE to Indian hydrological conditions. (1) The SHE has been verified on Indian data, although not for research catchments with good data coverage. However, such tests have successfully been carried out using data from other parts of the world. The present results indicate that the SHE is able to reproduce the rainfall-runoff process and give a physically reasonable representation of the intermediate hydrological processes for the characteristic monsoon environment. (2) The data requirements for SHE modelling are substantial. However, experience from the Narmada studies indicates that the main part of the required data already exists with different agencies representing meteorological, irrigation, agricultural, geological, and other professional fields, many of which are not usually contacted in traditional hydrological and water resources studies. (3) Fieldwork in connection with SHE modelling is of major importance as a supplement to the data available from existing sources. For a feasibility study the necessary measurements can be made in a matter of a few weeks. As

20

J.C. R E F S G A A R D ET AL.

far as model parameters are concerned, the fieldwork is likely to have most significance for evaluation of the soil hydraulic properties. However, very importantly, the fieldwork may give an improved assessment of the overall hydrological regime and the importance of the various hydrological processes within the catchment. (4) The quantity and quality of rainfall data is of the utmost importance for accurate simulation of catchment response. Uncertainty in the rainfall input most often defines the limit for simulation accuracy. It is, therefore, important to assemble and evaluate all rainfall records at a very early stage of a project. (5) Hydrological experience and judgement is very important in connection with data preparation and calibration of the SHE and interpretation of the results. Thus, the fact that SHE is more advanced and has a physically more correct process description than traditional hydrological models, does not imply that the input from the SHE modeller can be based on routine operation. On the contrary, SHE modelling most often deals with much more complicated hydrological problems than ~just" rainfall-runoff modelling and, therefore, requires, in general, more hydrological experience than does traditional hydrological modelling. (6) The SHE, owing to its generalized structure and process description, is in principle applicable to almost any hydrological regime in India and for most hydrological problems. However, owing to its complexity and data requirements, it is more costly to use than traditional, and simpler, hydrological models. Therefore, considering both hydrological and economic aspects, the SHE is recommended as the optimal toot for only some types of hydrological problems. (a) For rainfall-runoff modelling (extension of streamflow records from long historical rainfall series, flood forecasting, etc.) simpler models will in most cases be equally accurate and much cheaper to apply. Hence, SHE is not generally recommended for tackling problems, which are ~only' related to prediction of discharges from a catchment. (b) For problems dealing with prediction of the effects of man's activities, for which the traditional models are not applicable, SHE is particularly well suited and models of the SHE type are technically the only feasible option. Such types of application include: prediction of effects of land use change; simulation of interaction between surface water and groundwater, e.g. conjunctive use: water management in irrigation command areas; prediction of effects of climate change. (c) SHE is well suited as the hydrological basis for water-quality and soil erosion modelling, for which a detailed and physically correct description of the water flow processes is required. It should be noted that further work is already in progress at the ASHE organizations regarding

APPL]CAT|ON OF SHE TO INDIAN CATCHMENTS

I

21

development and testing of water-quality and soil erosion modules for the SHE modelling system. ACKNOWLEDGEMENTS

The project described was carried out under the ALA/86/19 financial agreement between the Government of India and the Commission of the European Communities. The cooperation of the Madhya Pradesh Irrigation Department, Narmada Valley Development Authority (NVDA) and many other data collection agencies, who have kindly extended their support to the project, has been invaluable. Without this the project could not have been carried out to its eventual level of success. The simulation studies of the six Narmada subbasins were carried out as case studies during project training activities by S.K. Jain, R.D. Singh, V.K. Lohani, R. Kumar, C.P. Kumar and S.K. Singh, scientists at NIH. The fruitful cooperation and interaction with them as well as many other NIH staff members who have contributed to the project work is acknowledged. REFERENCES Abbott, M.B., Bathurst, J.C., Cunge, J.A., O'Connell, P.E. and Rasmussen, J., 1986a. An introduction to the European Hydrological System - - Syst~me Hydrologique Europ6en 'SHE' 1: history and philosophy of a physically based distributed modelling system. J. Hydrol., 87: 45-59. Abbott, M.B., Bathurst, J.C., Cunge, J.A., O'Connell, P.E. and Rasmussen, J., 1986b. An introduction to the European Hydrological System - - Syst6me Hydrologique Europ~en 'SHE' 2: Structure of a physically based distributed modelling system. J. Hydrol., 87: 61-77. Aboujaoud~, A., 1991. Mod~lisation hydrologique de l'infiltrationdans les sols encrot~tes a dilT6rentes ~chelles spatiales. Th~se de Docteur de l'Universite Joseph Fourier, Grenoble, 218 pp. Aboujaoud&, A., Cunge, J.A. and Erlich, M., 1991. SHE - - un outil desimulation de l'impact des ph6nom~nes m6teorologiques et des am6nagements hydrauliques sur les transferts hydriques dans un bassin versant. Compte Rendu de XXle Journ6es de l'Hydraulique, Sophia Antipolis, 29-31 January 1991. Soci6t6 Hydrotechnique de France, Sofia-Antipolis, pp. 1.14.1-I.14.6. Ammentorp, H.C., Jensen, K.H., Christensen, T.H. and Refsgaard, J.C., 1986. Solute transport and chemical processes: the present state of the unsaturated zone component of the SHE modelling system. In: F. Stanburg (Editor), Int. Conf. on Water Quality in the Inland and Natural Environment, BHRA, June 1987, Bournemouth, UK. Fluid Eng. Centre, Cranfield, pp. 187-198. Bathurst, J.C., 1986. Physically-based distributed modelling of an upland catchment using the Syst~me Hydrologique Europ~en. J. Hydrol., 87: 79-102. Bathurst, J.C. and Cooley, K.R., 1992. Investigating basin response to snowmelt with the SHE at Reynolds Creek, Idaho. J. Hydrol., in press. Bathurst, J.C. and Purnama, A., 1991. Design and application of a sediment transport

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J.c. R E F S G A A R D ET AL.

modelling system. In: Sediment and Stream Water Quality in a Changing Environment: Trends and Explanation, Proc. of the IAHS Syrup., August 1991, Vienna. IAHS Publication No. 203, IAHS, Wallingford, pp. 305-313. Beven, K., 1989. Changing ideas in hydrology the case of physically based models. J. Hydrol., 105: 157-172. Engesgaard, P.K. and Jensen, K.H., 1990. Drainage flow modelling --Syv Creek. NPO-project BI4, National Agency of Environmental Protection, Denmark, 61 pp. Gupta, Ram K. and Varade, S.B., 1988. Hydrophysical properties and management of vertisols (Black Cotton Soils). Publication No. 32, Water and Land Management Institute, Aurangabad, Maharashtra, India. Hodnett, M.G. and Bell, J.P., 1981. Soil physical processes of groundwater recharge through Indian black cotton soils. Report No. 77, Institute of Hydrology, Wallingford, 38 pp. Hodnett, M.G. and Bell, J.P., 1986. Soil moisture investigations of groundwater recharge through black cotton soils in Madhya Pradesh, India. Hydrol. Sci. J., 31(3): 361-381. Jain, S.K., 1990. Application of SHE model to the Kolar subbasin of river Narmada. Report CS-33, National Institute of Hydrology, Roorkee, India, 54 pp. Jain, S.K., Erlich, M. and Seth, S.M., 1990. Field investigations in Kolar subbasin of river Narmada. Report TR-81, National Institute of Hydrology, Roorkee, India, 82 pp. Jain, S.K., Storm, B., Bathurst, J.C. Refsgaard, J.C. and Singh, R.D., 1992. Application of the SHE to catchments in India. Part 2. Field experiments and simulation studies with the SHE on the Kolar subcatchment of the Narmada River. J. Hydrol., 140: 25-47. Jensen, K.H., Refsgaard, A. and Bitsch, K., 1991. Investigations at Vejen landfill. Mathematical modelling. Lossepladsprojektet, Report M I/M2, Technical University of Denmark and Danish Hydraulic Institute, Copenhagen, 158 pp. Kauraw, D.L., 1982. In situ hydraulic properties of vertisols and water uptake by plant roots. Ph.D. Thesis, Department of Soil Science, JNKVV, Jabalpur, Madhya Pradesh. Kaushal, G.S., 1981. Characterization and classification of soils of Bargi Project (District - - Jabalpur and Narsinghpur). Ph.D. Thesis, Department Soil Science and Agricultural Chemistry, JNKVV, Jabalpur, Madhya Pradesh. Kumar, C.P., 1990. Application of SHE model to the Narmada (up to Manot) basin. Report CS-29, National Institute of Hydrology, Roorkee, India, 158 pp. Kumar, R., 1990. Application of SHE model to the Ganjal subbasin of river Narmada. Report CS-28, National Institute of Hydrology, Roorkee, India, 128 pp. Lohani, V.K., 1989. Application of SHE model to the Sher subbasin of river Narmada. Report CS-31, National Institute of Hydrology, Roorkee, India, 62 pp. Lohani, V.K., Refsgaard, J.C., Clausen, T., Erlich, M. and Storm, B., 1992. Application of the SHE for Irrigation Command Area Studies in India. ASCE, J. lrrig. Drain. Eng., in press. Madhya Pradesh Agricultural Department, 1986. Detailed soil survey report of Madhya Pradesh State Seed Farm Development Corporation, Begamganj Farm, Begamganj Tehsil, Raisen District. Soil Survey Report No. 17, Madhya Pradesh State Soil Survey Unit, Sagar. Madhya Pradesh Soil Survey, 1974-1975. Soil Survey Report of Bargi Project, district Jabalpur and Narsinghpur. Report No. 41, Madhya Pradesh Detailed Soil Survey Scheme. National Institute of Hydrology (NIH), 1991. Hydrological computerized modelling system (SHE). Final Report for the Indo-European Project ALA/86/19. Prepared by the Danish Hydraulic Institute in association with the University of Newcastle Upon Tyne and SOGREAH for the National Institute of Hydrology, Government of India, Horsholm, 390 pp. Refsgaard, A. and Jorgensen, G.H., 1990. Use of Three-dimensional Modelling in Ground-

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water Management and Protection. In: G. Gamboladi, A. Rinaldo, C.A. Biebbie et al. (Editors), Proc. VIII International Conf. on Computational Methods in Water Resources, Venice. Springer, Berlin, pp. 3-8. Refsgaard, J.C., Christensen, T.H. and Ammentorp, H,C., 1991. A model for oxygen transport and consumption in the unsaturated zone. J. Hydrol., 129: 349-369. Singh, R.D., 1990. Application of SHE model to the Barna subbasin of river Narmada. Report CS-32, National Institute of Hydrology, Roorkee, India, 80 pp. Singh, V.K., 1990. Application of SHE model to the Hiran subbasin of river Narmada. Report CS-30, National Institute of Hydrology, Roorkee, India, 140 pp. Storm, B., 1991. Modelling of saturated flow and the coupling ofthe surface and subsurface flow. In: D.S.Bowles and P.E. O'Connel (Editors), Recent Advances in the Modelling of Hydrologic Systems. Kluwer, Dordrecht, pp. 185-203. Storm, B. and Jorgensen, G.H., 1987. Simulation of water flow and soil erosion processes with a distributed physically-based modelling system. In: Proc. Vancouver Symp., August 1987, Forest Hydrology and Watershed Management. IAHS-AISH Publication No. 167, IAHS, Wallingford, pp. 595-608. Storm, B., Styczen, M. and Clausen. T., 1991. Three-dimensional modelling of nitrate transport in a catchment. In: Proc. Int. Conf. on Nitrogen, Phosphorus and Organic Matter, Helsingor, Denmark, 13-15 May 1991. National Agency of Environmental Protection, Copenhagen, pp. 23 40. Styczen, M. and Nielsen. S.A., 1989. A view of soil erosion theory, process, research and model building: Possible interactions and future developments. Quaderni di Scienza del Suolo, Vol. II. Centre di Studio per la Genesi, Classificazione e Cartografi del Suolo, Firenze, pp. 27-45. Sutcliffe, J.V. and Green, C.S., 1986. Water balance investigation of recharge in Madhya Pradesh, India. Hydrol. Sci. J., 31(3): 383-394. Sutcliffe, J.V., Agrawal, R.P. and Tucker, J.M., 1981. The water balance of the Betwa basin, India. Hydrol. Sci. Bull., 26(2): 149-158. Villholth, K., Jensen, K.H. and Fredericia, J., 1991. Field investigations of preferential flow behaviour. In: G. Kienitz, P.C.D. Milly, M. Th. van Genuchten, D. Rosbjerg and W.J. Shuttleworth (Editors), Proc. IAHS Syrup., August 1991, Vienna. IAHS Publication No. 204, IAHS, Wallingford, pp. 245-261. Wicks, J.M. and Bathurst, J.C., 1992. S H E S E D - U K - - a physically-based distributed erosion and sediment yield component for the SHE hydrological modelling system. J. Hydrol., in press. Wicks, J.M., Bathurst, J.C., Johnson, C.W. and Ward. T.J., 1988. Application of two physically-based sediment yield models at plot and field scales. In: Sediment Budgets, Proc. IAHS Symp. Porto, Alegre, Brazil. IAHS Publication No. 174, IAHS, Wallingford, pp. 583-591. Wicks, J.M., Bathurst, J.C. and Johnson, C.W., 1992. Calibrating the SHE soil erosion model for different land cover. ASCE, J.Irrig. Drain. Eng., in press.