Texas A&M University Department of Civil Engineering Instructor: Dr. Francisco Olivera CVEN689 Applications of GIS to Civil Engineering Determination of Urban Runoff Using ILLUDAS and GIS Tae Jin Kim 03. May. 2004 Abstract The flowing water function of surface area has been reduced rapidly by lasting progress of urbanization and industrialization. As the sewer pipes of urban area are established or extended, surface area and water route in urban river are mostly paved or connected to sewage box. Also, the peak discharge in urban area is increased due to the runoff enlargement and the watershed lag time reduction. Moreover, by the large-scale residential land development of lower reaches section of a river in urban area, the hydrologic phenomenons are changed and the flood damages in urban area are occurred frequently. In particular, because the damage cost and damage scale is increased relatively due to development rate and population concentration, it is required the accurate and rapid runoff analysis in urban area. Accordingly, in this study, we use Geographic Information System (GIS) and Illinois Urban Drainage Area Simulator (ILLUDAS) to get the urban runoff. The GIS can be used to select the available data according to need. The ILLUDAS can estimate the urban runoff more accurate than the existing methods. INTRODUCTION The flowing water function of surface area has been reduced rapidly by lasting progress of urbanization and industrialization. As the sewer pipes of urban area are established or extended, surface area and water route in urban river are mostly paved or connected to sewage box. Also, the peak discharge in urban area is increased due to the runoff enlargement and the watershed lag time reduction. Moreover, by the large-scale residential land development of lower reaches section of a river in urban area, the hydrologic phenomenons are changed and the flood damages in urban area are occurred frequently. In particular, because the damage cost and damage scale is increased relatively due to development rate and population concentration, it is required the accurate and rapid runoff analysis in urban area. A methodology of adjusting measured annual maximum discharge is presented [R. Edward Beighley, 2003]. The principles of integrated catchment management in south Africa is tested [A.M.W. Grobicki, 2001]. The spatially continuous data in the Reynolds Creek Experimental Watershed is provided [M. Seyfried, 2001]. The Hydrological Land Use Change (HYLUC) model is developed [Ian R. Calder, 2003]. There are many methods to calculate the runoff in urban area. Also, many people try to get the spatial data. Accordingly, runoff through storm sewer pipe in college station is calculated using GIS and ILLUDAS,. METHODOLOGY To calculate the runoff in college station, we use three programs: AUTO-Computer Aid (CAD), Arc Geographic Information System (GIS), and Illinois Urban Drainage Area Simulator (ILLUDAS), as shown in Figure 1. The figure 1 demonstrates the procedures to calculate the urban runoff in college station.
Runoff Computation in Urban area Auto-CAD Arc-GIS ILLUDAS Elevation ArcMap ArcToolbox PrePro2004 Runoff Calculation Spatial Analyst Export or Import data Watershed delineation Editor Map projections Geoprocessing Other functions Figure 1 Flow chart for calculating runoff in urban sewer pipe network Among these programs, at this time, I introduce only ILLUDAS. The ILLUDAS is an Illinois Urban Drainage Area Simulator. Its program can calculate runoff, peak discharge, and flow carrying capacity in urban sewer pipe network or design the sewer pipe diameter depending on the discharge in sewer pipe. This program is a Modified British Road Research Laboratory (BRRL) Model. The BRRL model can consider only the directly connected impervious area. To overcome the defects of the BRRL model, ILLUDAS consider the directly connected impervious area and grassed area. As shown in figure 2, ILLUDAS consists of four input data format: Basin parameter, Rainfall parameter, Sewer pipe data, and sub-basin data. Among these data, I use ArcGIS to get the total area, soil type, slope, pipe type, diameter, sub-basin area, surface slope and Impervious & Grassed area. Table 1 shows the detail information of ILLUDAS ILLUDAS INPUT Basin parameter Rainfall parameter Sewer pipe data Sub-basin data Total area Rainfall duration Side slope Area Soil type Return period Slope Logest pipe line Manning's coefficient Total rainfall Pipe type Surface slope and so on and so on Diameter Soil type and so on Figure 2 ILLUDAS Input Format
Table 1 ILLUDAS Input data Basic parameter Rainfall data Sewer pipe data Sub basin data Total area Rainfall Branch number Branch number Initial abstraction of paved area Rain in time interval Strom sewer section number Storm sewer section number Initial abstraction of grassed area Number of rainfall time interval End branch Sub basin total area Soil kind Delta t(min) Continuing branch Direct paved area minimum diameter in design Standard distribution Option Direct paved area rate Manning Roughness coefficient Duration Reach Indirect paved area Return period Slope Indirect paved area rate Total rainfall Manning Roughness coefficient Inlet time in paved area AMC Pipe shape Inlet time in paved area rate Diameter Longest pipe line Height of pipe Surface slope in paved area Width of pipe Grassed-area related to runoff Side slope Grassed-area related to runoff rate Allowance discharge Inlet time in Grassed-are Rainfall rate Pipe length in Grassed-area Allowance storage Surface slope in grassed-area Test end Hydrologic soil group Hydrograph print out APPLICATION The study area is a college station in Texas. The number of sewer pipe line and sewer pipe manhole in college station is 4624 and 4619, respectively. The study area is 40.6828 square mile [City of College station, 2002]. The calculation of runoff consists of five steps: Step1: Get the elevation data of college station using AUTO-CAD I use AUTOCAD to get the elevation data from contour map n college station. The result is exported to the ArcGIS as shown in figure 3. Figure 3 Elevation data in college station
Step2: Get the raster data of the college station using Arc-GIS To get the various data about the study area, it is necessary to get the raster data in college station. The procedure consist four steps. First step, Elevation data are exported to ArcGIS. Second step, The Exported elevation data is converted to raster data using Spatial Analyst. This raster data have no cell data. So, it is necessary to require other steps. Third step, the raster data is changed integer data using raster calculator and is converted to point shape file. The last step, the point shape file is converted to the raster data using Inverse weighted method. The result is show in figure 4. Elevation Data Export Elevation.shp ` Spatial Analyst Convert to Raster Raster Point.shp Raster Raster Calculator int [(raster)] Convert to feature Interpolate to Raster (120m) Inverse Weighted Method Figure 4 Procedure to get the raster data and raster data in college station Step 3: Select the sewer pipe line and sewer manhole (1ft =< sewer pipe diameter <= 3ft) It is difficult to calculate the runoff of all the storm sewer pipes. So, I select the several storm sewer pipes according to the bigger than 1 ft sewer pipe diameter and smaller than 3ft sewer pipe diameter. Also, I select manhole according to the selected sewer line. The original sewer line and the selected sewer line are shown in figure 5. The figure 6 shows the procedure of selecting the sewer pipe lines and manholes. Figure 5 Original & Selected Sewer pipe lines and manholes
Sewerline Select 1=<pipe diameter<=3ft Dissolve to Diameter size Manhole ` Select manhole to each sewer line Selected sewerline and manhole Figure 6 Procedure of selecting the sewer pipe lines and manholes. Step 4: Delineate the watershed according to the selected sewer pipe lines To get the sub-basin in college station, I use PrePro2004 in ArcGIS. The PrePro2004 has no function to delineate the watershed according to the sewer line manhole. So, I assume two things. First, I use burn-in function according to sewer line. The unmatched reach line is edited to the sewer line. However, it is impossible to match the exactly the same. Second, when I determine the outlet point, I delete the outlet point except outlet point, which is matched to the sewer line manhole point and add the outlet point according to the manhole point. The result is shown in figure 7. The red line is sewer pipe line and the black line is generated line. PrePro2004 (Reach=sewer lines) Burn-in to sewer lines Edit generated reach to sewer lines Outlet points = Sewer line mahole points Get sub-basin to sewer pipelines Figure 7 Procedure to get the sub-basin data and generated sewer line The figure 8 shows the generated sub-basin. The number of sub basin is 31. The number of selected sewer line is 233. The number of selected manhole is 33. The manhole number 6 is target point to calculate runoff because the point has the lowest elevation.
1 10 1 0 2 3 15 18 4 27 26 5 2 5 4 Target Point 7 8 3 9 9 6 12 10 19 20 22 8 16 14 17 17 21 13 6 13 15 28 29 22 23 16 31 24 25 25 26 24 23 14 29 30 7 32 31 28 12 11 Figure 8 Generated sub-basin To get the information of impervious area and grassed area, I intersect the sub basin area shape file and land use shape file and upgrade. The result is shown in figure 9. To get the information of the soil type, I intersect the sub basin area shape file and soil type shape file and upgrade. The result is shown in figure 10. Watershed Land use Intersect and Upgrade Land use to Watershed Figure 9 Intersected land use shape file in watershed Watershed Soil type Intersect and Upgrade Soil type to Watershed Figure 10 Intersected land use shape file in watershed
Step 5: Calculation runoff of the target point using ILLUDAS As shown in figure 2, it is necessary to get rainfall data to calculate runoff in store sewer pipe network. In this study, I use frequency-based design storm and block method. The rainfall data is generated according to 2yr, 5yr, 25yr, 50yr, and 100yr recurrence interval. The table 2 shows the coefficient for a recurrence interval T year. The rainfall is shown in Table 3. Table 2 Coefficients for a recurrence interval T year T years a b c 2year 65 8 0.806 5year 76 8.5 0.785 25year 89 8.5 0.754 50year 98 8.5 0.745 100year 96 8 0.73 Table 3 Generated rainfall data time(min) 2yr 5yr 25yr 50yr 100yr 0 0.00 0.00 0.00 0.00 0.00 20 1.07 1.56 2.47 2.96 3.33 40 1.48 2.13 3.32 3.96 4.41 60 1.76 2.52 3.89 4.63 5.13 80 2.19 3.11 4.74 5.63 6.20 100 2.93 4.12 6.19 7.31 8.00 120 4.58 6.32 9.25 10.86 11.72 140 11.08 14.73 20.46 23.66 24.94 160 37.52 46.40 60.28 68.40 71.38 180 6.46 8.80 12.61 14.71 15.72 200 3.57 4.97 7.39 8.70 9.46 220 2.50 3.54 5.36 6.34 6.97 240 1.95 2.78 4.26 5.07 5.61 260 1.61 2.30 3.57 4.26 4.74 280 1.28 1.85 2.91 3.48 3.89 300 0.93 1.36 2.16 2.60 2.93 320 0.00 0.00 0.00 0.00 0.00
RESULTS The peak runoff values at the target point are shown in table 4. The peak runoff at the target point is 2, 5, 25, 50, and 100 year is about 4717, 5967, 7018, 9184, and 9623 CFS, respectively. Table 4 T-year Total precipitation Peak Runoff (mm) (in) (CMS) (CFS) Target point peak runoff 300 250 2yr 80.89 3.18 133.57 4717.23 5years 106.48 4.19 168.97 5967.44 25years 148.86 5.86 198.73 7018.46 50year 172.57 6.79 260.06 9184.42 100year 184.41 7.26 272.48 9623.05 200 150 100 50 0 Total precipitation (mm) Peak Runoff (CMS) 2yr 5yr 25yr 50yr 100yr CONCLUSION Its method is more accurate runoff calculation method than paper map method in urban area. Second, it is a new approach to delineate watershed of sewer network system in urban area. Third, even though it is not shown the whole results of ILLUDAS, the results of ILLUDAS can examine the flow capacity in storm sewer pipe. Last, we can design the storm sewer pipe diameter depending on the calculated flow capacity in each sewer pipe. FUTURE RESEARCH It is necessary to interface GIS and runoff calculation model of storm sewer pipe and develop the watershed delineation method in urban area. REFERENCE 1. A.M.W.Grobicki., 2001. Urban catchment management in a developing country: The Lotus River project, Cape Town, South Africa. Water Science and Technology. Vol.44. No2-3, pp313-319 2. Booth and Mitchell, Getting Started with ArcGIS, ESRI Press, 1999 3. College station. Embracing the Past, Exploring the future, College station. Demographic Report. 2002. 4. Getting to know ArcGIS desktop, ESRI Press, 2001 5. Ian R. Calder., 2003. Assessing the water use of short vegetation and forest: Development of the Hydrologic Land Use Change (HYLUC) model. Water Resources research. Vol.39. No. 11, 1318
6. ILLUDAS Program: http://www.hydrosys.net/ 7. M. Seyfried, R. Harris, D. Marks, and B. Jacob., 2001. Geographic database, Reynolds Creek Experimental Watershed, Idaho, United States. Water Resources research. Vol.37. No. 11, pp2825-2829 8. R. Edward Beighley, Gleen E. Moglen., 2003. Adjusting measured peak discharges from an urbanizing watershed to reflect a stationary land use signal. Water Resources research. Vol. 39. No4, 1093