Application of Gis for Hydrological Analysis
5 OTHER APPLICATIONS
5.1 Water budget model
Various water budget analysis procedures were recently evaluated by Cumming Cockbum Limited on behalf of the Ontario Ministry of Natural Resources (CCL, 1999).
Currently, a water budget model which utilizes the advanced GIS programming techniques and powerful display and data manipulating functions is under development for use on an individual watershed basis. The simplest form of water budget over a large area for mean annual conditions takes the following form:
E = P-R (7)
where E is mean annual evapotranspiraticn, P is mean annual precipitation and R is mean annual runoff.
Data from approximately 1600 rain gauges and 700 hydrometric stations are available in Ontario, and these data were used to interpolate the spatial variations of the mean annual precipitation (Figure 6) and mean annual runoff (Figure 7). Using GIS map overlaying and
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manipulating functions, the mean annual evaporation/evapotranspiration was then computed (Figure 8).
The evaporation/evapotranspiration can also be estimated using analytical equations.
These computations would be useful for small area water balance analysis. The water balance model under development takes into consideration the following factors:
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meteorological factors (temperature, radiation, wind, etc.) interception
evapotranspiration snowmelt
overland flow percolation
The catchment is represented by quadratic raster cells. The vegetation layer on top is the major linkage between soil and atmosphere. If rainfall exceeds the infiltration capacity, surface runoff occurs. The lateral transport processes can be surface runoff, macropore and soil matrix moisture transport and groundwater flow. They are simultaneously connected to the soil moisture in the horizon considered. The surface flow direction can be determined by the D8 method (eight direction four point method) based on the direction of steepest descent.
From this, the flow accumulation of a grid can be derived (Figure 9).
5.2 Regional sediment loading analysis
Environment Canada established hydrometric stations to measure the streamflow and sedimentation input to the Great Lakes. However, the valuable sedimentation data has not been systematically analyzed. Cumming Cockbum Limited recently analyzed the total mean annual sediment loadings from Canadian sources into the Great Lakes using GIS technology as a tool in the analytical procedures. A regional sediment estimation technique combined with a GIS model was developed to estimate the sediment input to the Great Lakes from the gauged and ungauged watersheds.
A group of variables was identified which are closely correlated to the sediment loading. These variables are the mean annual runoff (MAR), catchment slope, the area of sands and gravels (Al), the area of silts and clays (A2), the area of undifferentiated material or bedrock (A3), wind stress and storm peak intensities.
Regression equations were developed and the equations were utilized to estimate the sediment loadings for the areas where no measurements are available. It was found that the sediment loadings to the Great Lakes are closely related to the mean annual runoff and the area of sands and gravels (Al). The results were then imported into the GIS program to utilize the powerful display, visualizing, data management and analysis functions. An example is presented in Figures 1 Oa and 1 Ob.
The sediment loadings were also analyzed to determine if trends exist in the data. The sediment variations with time were plotted for each of the recording stations and the sediment yield was spatially evaluated to identify areas where more sediment yield may be expected.
Figure lob shows example estimates for the total sediment loading to Lake Erie from the computations and comparisons. Four historical storms which occurred in the Ontario region were analyzed:
The Timmins rainfall event occurred in 196 1, and resulted in significant flood damage from 193 mm of rainfall occurring over a 12 hour period. The Timmins event has been adopted by the Ontario Ministry of Natural Resources as the Regional Storm for Northern Ontario. The total rainfall volume above the 50 mm rainfall depth is estimated to be 0.7 km3 over a total area of 9487 km2.
A significant rainstorm event associated with Hurricane Hazel occurred in Southern Ontario in 1954. This storm was adopted by the Ontario Ministry of Natural Resources as the relative frequency of recurrence, rainfall volume and spatial characteristics of rainstorm events (Belore, H.S. et al, 1999). The collection and GIS analysis of data describing additional storm rainfall events is proceeding in an attempt to identify the need for modifications to the use of the existing Regional Design Storms in the Province of Ontario.
This analysis could be further expanded to determine whether such changes may be occurring across Canada and elsewhere.
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6 CONCLUSIONS
It was concluded that the design storm estimating program provides a tool to account for the variations in the design storm field which may be economically significant for local projects.
The estimation of flood and low flow characteristics for ungauged sites have relied on regionalization techniques in the past. We present an alternative which is called the GIS spatial continuously varying method. Promising results have been obtained. More research is needed to compare the predicting accuracies for the regional and spatial methods.
The proposed water budget model can perform analyses using both the spatial distributed parameters method and the lumped parameters method. The applicability of each method depends on the availability of data. Research on how to incorporate the surface water system and the detailed groundwater simulations at different time steps would result in significant improvement in modelling approaches.
GIS techniques are extremely useful and suitable for regional hydrological investigations. Some promising results have been obtained. It has come to a stage where some integrated hydrological model within a GIS framework can be established. Works toward this direction would be valuable for both GIS and hydrology.
7 REFERENCES
Becker, A. and B. Pfuetzner, 1990. Larger-Scale Hydrological Modelling for Regional Transferring of Hydrological Information, in Regionalization in Hydrology, edited by M.A. Beran and M. Brilly et al., IAHS Publication No. 191, 1990.
Belore, Harold, Balins, Juris and Roger Payne, 1999. Flood and Drought Risk Models for Tailings Management Areas, Proceedings of Canadian Dam Association Annual Conference, Sudbury Ontario, October, 1999.
Curnming Cockburn Limited, 1990. Regional Analysis of Low Flow Characteristics, Southwestern and West Central Regions, for the Ministry of Environment.
Cumming Cockburn Limited, 1991. A Report on Regional Analysis of Low Flow Characteristics, Central and Southeastern Regions, for the Ministry of Environment.
Cumming Cockbum Limited, 1993. Regionalization of Low Flow Characteristics, Northeastern and Northwestern Ontario, for the Ministry of Environment and Energy.
Cumming Cockburn Limited, 1995. Working Paper: A Regional Flood Frequency Study (Province of Ontario), for the Ministry of Natural Resources, Conservation Authorities and Water Management Branch.
Cumming Cockburn Limited, 1998. Regionalization of Flood Characteristics in Ontario, for the Ministry of Natural Resources, 1998.
Cumming Cockburn Limited, 1999. Flood Regionalization for Ontario, for the Ministry of Natural Resources.
Dingman, S.L., 1994. Physical Hydrology, Prentice-Hall Inc., A Simon & Schuster Company, Englewood Cliffs, New Jersey 07632.
Faucher, C., Rousselle, Jean et al., 1993. Flood Frequency Analysis: Regional Approach Versus Spatial Approach, Geographic Information Systems and Water Resources, American Water Resources Association, 1993. (Draft)
Grumazescu, H., Stancalie, G. and C. Ungureanu, 1990. Remote Sensing Techniques for Determining the Regionally Variable Characteristics of Drainage Basins, in
Regionalization in Hydrology, edited by M.A. Beran and M. Brilly et al., IAHS Publication No. 19 1, 1990.
Hosking, J.R.M. and J.R. Wallis, 1997. Regional Frequency Analysis, An Approach Based on L-Moments, Cambridge University Press, 1997.
Kenny,Frank,l999,Personal Communication, Remote Sensing Analyst ,Ontario Ministry of Natural Resources, Peterborough, Ontario
Kirk, K.G., 1991. Residual Analysis for Evaluating the Robustness of Inverse Distance, Kriging and Minimum Tension Gridding Algorithms, GeoTechGeoChautangua 1991 Conference Proceedings, Lakewood, Colorado.
Ojo, Oyediran, 1990. Variation in Hydroclimatic Components and the Concept of Regionalization in West Africa, in Regionalization in Hydrology, edited by M.A.
Beran and M. Brilly et al, IAHS Publication No. 191, 1990.
Pilon, P.J., Day, T.J., Yuzyk, T.R. and R.A. Hale, 1996. Challenges Facing Surface Water Monitoring in Canada, Canadian Water Resources Association, Vol. 21, No. 2, 1996.
Riggs, H.C., 1990. Estimating Flow Characteristics at Ungauged Sites, in RegionaZization in Hydrology, edited by M.A. Beran and M. Brilly et al., IAHS Publication No. 191,
1990.
Servat, E. and J.M. Lapetite, 1990. Data Acquisition Within a Regional Scale, The Experience of the Remote Satellite Transmission in West Africa, in Regionalization in Hydrology, edited by M.A. Beran and M. Brilly et al., IAHS Publication No. 191,
1990.
Strahler, A.N. 1964. Geology - Part II, handbook of Applied Hydrology, New York:
McGraw-Hill Book Company, 1964.
Wiltshire, S. and M. Beran, 1986 (a). Multivariate Techniques for the Identification of Homogeneous Flood Frequency Regions, in Regional FZood Frequency Analysis, edited by V.P. Singh, D. Reidel Publishing Company, 1986.
Wiltshire, S. and M. Beran, 1986 (b). A Significant Test for Homogeneity of Flood Frequency Regions, in Regional FZood Frequency Analysis, edited by V.P. Singh, D.
Reidel Publishing Company, 1986.
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* METEROLOGICAL STATION
Figure 1. Meteorological Stations Used in the Analysis
Figure 2. Rainfall Intensities 100 Year, 1 Hour
Figure 3. 1:lOO Year Storm Derived Based on Regional Data
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Figure 5. Flood Frequency Curve Derived for a Site in Toronto
Figure 6. Mean Annual Precipitation (mm)
Figure 6. Mean Annual Precipitation (mm)
Figure 7. Mean Annual Runoff (mm)
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Figure 8. Mean Annual Evapotranspiration (mm)
Figure 9. Spatial Water Balance Analysis Using GIS
Figure 10a. Annual Suspended Sediment Discharge to Lake Erie
Figure lob. Total sediment Load from Gauged and Ungauged Area (t jyr) to I ,ake Erie
I i
I I
““..“--.--- 4. ..&
Figure 11. Extreme Storms
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