|S.M. Seth, S.K. Jain & M.K. Jain
National Institute of Hydrology, Roorkee 247667 (U.P)
The success of planning for developmental activities depends on the quality and quantity of information available on both natural and socio-economic resources. It is, therefore, essential to devise the ways and means of organising computerised information system. These systems must be capable of handling vast amount of data collected by modern techniques and produce upto date information. Remote Sensing technology has already demonstrated its capabilities to provide information on natural resources such as crop, land use, soils, forest etc on regular basis. Similarly, Geographic Information Systems (GIS) are the latest tools available to store, retrieve and analyze different types of data for management of natural resources. GIS facilitates systematic handling of data to generate information in a devised format. Thus it plays an important role in evolving alternate scenarios for natural resources management.
Remote Sensing (RS) data and Geographical Information System (GIS) play a rapidly increasing role in the field of hydrology and water resources development. Although very few remotely sensed data can be directly applied in hydrology, such information is of great value since many hydrologically relevant data can be derived from remote sensing information. One of the greatest advantage of using RS data for hydrological modeling and monitoring is its ability to generate information in spatial and temporal domain, which is very crucial for successful model analysis, prediction and validation. However, the use of RS technology involves large amount of spatial data management and requires an efficient system to handle such data. The GIS technology provides suitable alternatives for efficient management of large and complex databases.
Image data have been used as a primary source of natural resources information in thematic mapping which in turn is utilised in various hydrological studies. The remote sensing data provides synoptic view of a fairly large area in the narrow and discrete bands of the electromagnetic spectrum at regular intervals. The space borne multispectral data enable generating timely, reliable and cost effective information on various natural resources, namely surface water, ground water, land use/cover, soil, forest cover and environmental hazards, namely waterlogging, salinity and alkalinity, soil erosion by water etc. For many hydrological purposes, remote sensing data alone are not sufficient and need to be merged with data from other sources. Hence a multitude of spatially related (i.e. geographic) data concerning topography, rainfall, evaporation, vegetation, geomorphology, and soils have to be considered. Also of interest are social and economic data related to where the demand is for water for urban and industrial supplies, irrigation, etc. In addition, technical data are required, such as locations and types of tubewells, rain and river gauges, etc. GIS provides an extremely useful technology for considering the interaction between spatially distributed resources. Some typical hydrological studies carried out in National Institute of Hydrology involving application of remote sensing and geographic information system are discussed in following sections.
CASE STUDIES CARRIED OUT IN NIH
The National Institute of Hydrology, with its Head Quarters at Roorkee (U.P.) and six regional centres located in different parts of the country viz. Belgaum (Karnatka), Jammu (J&K), Guwahati (Assam), Patna (Bihar), Kakinada (A.P.) and Sagar (M.P.), has been carrying out research on various aspects of hydrology and water resources using remote sensing and GIS techniques. These studies cover different hydrologic processes occurring in a catchment e.g. rainfall-runoff modelling, soil erosion, reservoir sedimentation, land use/cover and land capability studies, watershed studies, snow and glacier melt etc.
Soil erosion assessment using remote sensing and GIS technique This study was carried out for the estimation of soil erosion based on the Geomorphological Characteristics for Jawai dam catchment in India using GIS technique. In this study satellite data IRS-1B was used to determine the land cover, the other input variables have been determined from topographic and hydromet data. The geomorphological characteristics of a catchment represent the attributes of the watershed that can be employed in its hydrologic behaviour. The important characteristics from the hydrological studies point of view include the linear, areal and relief aspects of the catchments, morphometric characteristics of different sub-catchments and their interrelationship. Regression analysis has been carried out for Jawai dam catchment using Integrated Land and Water Information System (ILWIS).
GIS Based Integrated Approach For Land Capability Classification In Bargi Command Area Land capability is the basis of watershed management programs. The basic principle of soil and water conservation is to use the land according to its capability and treat the land according to its needs. Land capability classification indicates the hazards of soil and water erosion, waterlogging etc. and these hazards limit the use of land for particular purposes only. For studying land capability classification beside the climatic factors, parameters related with watershed characteristics are required. For such parameters GIS is one of the best available tools. In the present study soil type, land use/land cover is input in GIS for analysis. From GIS analysis small scale land capability map is obtained.
Integration of GIS and remote sensing in soil erosion studies In this study USLE has been applied to a part of Banjar sub-basin in Narmda basin. All the parameters required were generated in GIS package ILWIS. After integration of these parameter in GIS environment the soil loss was estimated. The erosion estimation was made without management (considering only the physical factors), during monsoon season and non-monsoon season. Under first condition, maximum potential erosion losses were estimated under prevailing rainfall erosivity without crop cover or supporting control practices. In monsoon season and non-monsoon season the factors C and R were changed and the effect were analysed. The rate of erosion is high under physical conditions reflecting the effect of rainfall and harsh topography
SLURP Model and GIS for estimation of runoff in a part of Satluj In this study the SLURP watershed model was applied in a part the Satluj catchment located in the western Himalayas, India. The SLURP model, developed at NHRI, Canada, is a distributed conceptual model which simulates the behaviour of a watershed by carrying out vertical water balances for each element of a matrix of land covers and sub-areas of a watershed and then routing the resulting runoff between sub-areas.
It has been shown that the SLURP hydrological model can be applied to a basin in India using available meteorological data, topographic data and satellite imagery. A GIS was used to bring the different data sets together and to compute parameters for the hydrological model, showing that a GIS can play an important role in hydrological modelling. The GIS database can be readily updated from time to time if any change occurs in the basin. In this study, the model was eventually applied for six years of daily data showing good results. The model results show that the local runoff from rainfall is a small proportion of the total runoff (including snowmelt) and that improved results will be expected when we include upper portion of the catchment.
Soil Erosion and sediment yield modelling using kinematic Wave in GIS Environment In this study GIS techniques have been utilised for spatial discretization of a catchment in to a time-area segments to be used in numerical solutions of the governing differential equations in rainfall-runoff-erosion process. Various thematic layers such as soil, land use, slope, flow direction, DEM were generated for the Karso catchment in Bihar using various tools available in GIS. These thematic layers were further utilised to generate attribute information such as Manning's "n", USLE "K" and "C" parameters for use in rainfall-runoff-soil erosion model. Based on DEM and related attribute information of the catchment, time-area map of the catchment was prepared and used for spatial discretization of the catchment.
Watershed Modelling With GIS Based Distributed Unit Hydrograph Approach In this study a spatially distributed unit hydrograph for Temur watershed at railway bridge no.293 (M. P.) has been developed. The method of distributed unit hydrograph computation allows for spatial non-uniformity of excess rainfall. Consequently, it is based on the time-area method derived using GIS. The GIS allows development of a watershed's channel network for calculation of realistic travel times, it handles the distributed excess rainfall in calculating local surface runoff rates as inputs for channel flow and it compiles the time-area diagram from which distributed unit hydrograph is derived.
Flood estimation using a GIUH based on a conceptual rainfall-runoff model and GIS Estimation of design flood for hydrological design of various water resources structures, particularly for medium and major water resources schemes, has been one of the most active areas of research for the hydrologists and water resources engineers. Geomorphological Instantaneous Unit Hydrographs (GIUH) have been proposed by several engineers as a tool to simulate runoff hydrographs from rainfall for ungauged catchments. The important geomorphological parameters which represent the linear, areal and slope aspects of the catchement are required to be evaluated either from toposheets or from other indirect means. Application of GIS package provides an efficient and accurate means for the evaluation of these characteristics.
GIS for estimation of direct runoff potential For the estimation of the amount of direct runoff that will be produced from a basin, various hydrologic models are available. Soil Conservation Services (SCS) model is most widely used for the estimation of direct runoff. All the factors of SCS model are geographic in character. Due to the geographic nature of these factors, SCS runoff model can easily be modelled into GIS. In this study, Kolar subbasin of Narmada has been chosen for carrying out runoff potential estimation using ILWIS. For the rainfall events of 12, 13 and 14th. August 1989, direct runoff was computed using SCS equation.
Reservoir sedimentation study for Ukai dam using satellite data In the present study, the sedimentation rate and volume was determined in the Ukai reservoir using the remote sensing data. Based on the annual maximum and minimum observed levels, the post-monsoon period of the year 1993-94 was chosen for analysis. Remote sensing data of IRS-1B satellite and LISS-II sensor was acquired for eight different dates and revised water spread area was extracted. The standard signature characteristics of different surface features (water, soil and vegetation) were utilised for separating water pixels from other surface features. The resulting imagery of water pixels was compared with the standard FCC and near-IR imagery.
In order to meet the growing demand for food, fuel and fodder of ever increasing population land and water resources need to be optimally utilised. It requires timely and reliable information on available land and water resources which could be derived from space borne multispectral data. GIS has evolved as a highly sophisticated data management system to put together and store the voluminous data typically required for hydrological studies. Thus remote sensing and GIS together provide information base for efficient management of water resources. The synoptic view provided by satellite remote sensing and the analysis capability provided by GIS offer a technologically appropriate method for studying these resources. The National Institute of Hydrology has carried out above mentioned studies and many other studies related with land use/land cover mapping, reservoir sedimentation, snow cover and snow melt modelling, soil erosion studies, rainfall runoff modelling in various parts of India. These studies have demonstrated capabilities of remote sensing and geographic information system in hydrological applications.
While application of remote sensing and GIS techniques in hydrology has made considerable progress, still more remains to be done to make these tools operationalised. Sustained efforts in consolidating results obtained so far and in developing operational methodology packages are needed. There is need to evolve a well co-ordinated programme in this area with focus on developing of standard methodologies and software as well as training and technology transfer. There is also need for wide spread availability of remote sensing and GIS outputs in digital mode for various applications in water sector. Remote sensing and geographic information system have to play a vital role in decision support system for various activities related with development and management of land and water resources in an environmentally sound and sustainable manner.
- Kothyari, U.C., S.K.Jain,' Sediment yield estimation using GIS', Hydrological Sciences Journal , 46(2), December, 1997
- Jain, M.K. GIS based rainfall runoff modelling for Hemavathi catchment. CR/AR 22/96-97, National Institute of Hydrology, Roorkee.
- Jain, M.K. Watershed modelling with GIS based distributed unit hydrograph approach. CS/AR 8/97-98, National Institute of Hydrology, Roorkee.
- Jain S.K., Hemant Chowdhary, S.M.Seth, R.K.Nema,' Flood estimation using a GIUH based on a conceptual rainfall-runoff model and a GIS, ITC Journal 1997-1.
- Jain S.K., G.W.Kite, Naresh Kumar, T.Ahmad,'SLURP Model and GIS for estimation of runoff in a part of Satluj catchment, India', Hydrological Sciences Journal, 43(6), December, 1998.
- Jain S.K., K.K.Dash, Ranvir Singh,'GIS for estimation of direct runoff potential', Journal of Indian Water Resources Society, Vol.2, No.1 ,January, 1996
- Jain, S.K.,' Integration of GIS and Remote Sensing in soil erosion studies CS(AR) 186, 1995-96
- Jain, S.K.,' Soil erosion assessment using Remote sensing and GIS technique, CS(AR) 204, 1995-96
- Rathore D.S. and S.K.Jain,' Land capability classification in a part of Narmda basin, CS(AR) 178, 1994-95