LabAssignment 5

(Revision 4) Assignment 5 River Floods Complete Unit 8 before attempting this assignment. This assignment (worth 100 marks) makes up 5% of your final grade. Materials To complete this assignment, you will need the following materials. Please collect them now, before you proceed.  Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.). Upper Saddle River, NJ: Prentice Hall.  Keller, E. A. (2012). Introduction to Environmental Geology (5th ed.). Upper Saddle River, NJ: Prentice Hall. Overview In this assignment we explore the nature of river floods, problems caused by flooding, and potential mitigation measures. Flood Frequency Reading Assignment Keller, E. A. (2012). Introduction to Environmental Geology (5th ed.).  Review “River Velocity, Discharge, Erosion, and Sediment Deposition” (pp. 292–294) and “River Flooding” (pp. 298–304). Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “Introduction” (p. 154).  “Part A. Flood Frequency and Major Floods” (p. 155). Questions (50 marks) Answer questions 1–8 (pp. 155–157) in Investigations in Environmental Geology (3rd ed.). For questions 1–6 use the Mercer Creek-Data Set 1 and for questions 7–8, use the Mercer Creek Data Set-2 (to repeat steps 1–7). Year Peak Flood Recurrence Geology 207: Introduction to Environmental Geology 1

(Revision 4) Discharge Ran k Interval 195 7 180 9 1.33 195 8 238 2 6.00 195 9 220 4 3.00 196 0 210 5 2.40 196 1 192 7 1.71 196 2 168 10 1.20 196 3 150 11 1.09 196 4 224 3 4.00 196 5 193 6 2.00 196 6 187 8 1.50 196 7 254 1 12.00 Year Peak Flood Discharge Rank Recurrence Interval 1979 518 5 2.40 1980 414 7 1.71 1981 670 2 6.00 1982 612 4 3.00 1983 404 8 1.50 1984 353 9 1.33 1985 832 1 12.00 1986 504 6 2.00 1987 331 10 1.20 1988 228 11 1.09 1989 664 3 4.00 Geology 207: Introduction to Environmental Geology 2

(Revision 4)  “Large Floods in the United States” (p. 157). Questions (30 marks) Answer questions 12–14 (p. 157) in Investigations in Environmental Geology (3rd ed.). A copy of Figure 10.2 for your use is provided at the end of this assignment (labelled Figure 5.2). 12- What is the general trend in flood loss in the United States between 1900 and 2000 as determined from Table 10.2 and your graph? It is a growing trend; the cost is increasing over the decades. 14- a. For flood damage losses in the 20th century in Figure10.2, describe and explain the trend. Flood damages from one decade to another could vary for more or less, but the overall trend is upwards, growing together with population growth. With more development, more people, more urbanization, the costs of the flood are also be bigger. b. What is the role, if any, of growth in population and rising flood losses in the 20th century? Growth in population and development is a major factor contributing to rising flood losses over the 20th century. As more people move into floodplain areas and build homes, businesses, and infrastructure, there are simply more people and assets exposed and vulnerable to flooding when waters rise. This largely explains the upward trend in aggregate flood damages over time. Geology 207: Introduction to Environmental Geology 4

(Revision 4) c. What other factors contribute to increased losses? Expansion of impervious surfaces like paved roads, parking lots, rooftops, and compacted soils makes the water stay in place for longer. Deforestation and reduction of wetlands are also factors, since the area would not natually have any construction, the water would be able to run free. Increased property values. Inflacion makes costs of everything rise overtime. The Discharge/Area Ratio Reading Assignment Foley, D., McKenzie, G. D., & Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.).  “The Discharge /Area Ratio” (p. 157). Questions (20 marks) Answer questions 17–18 (pp. 157–159) in Investigations in Environmental Geology (3rd ed.). A copy of Figure 10.3 for your use is provided at the end of this assignment (labelled Figure 5.3). River Location Drainage Basin Area (km²) Maximum Discharge (m³/s) Q/A Ratio (m³/s/km²) Woallva Hawaii 58 2,470 42.6 Yaté New Caledonia 435 5,700 13.1 Pioneer Australia 1,490 9,840 6.6 Tam Shul Taiwan 2,110 16,700 7.9 Eel Scotia California 8,060 21,300 2.6 Han Koan South Korea 23,880 37,000 1.5 Cheng Jiang China 1,010,000 110,000 0.1 Lena USSR 2,430,000 190,000 0.1 Amazon Brazil 4,640,000 350,000 0.1 Geology 207: Introduction to Environmental Geology 5

(Revision 4) Figure 5.1. Flood frequency curve based on data from Table 10.1 (Foley, McKenzie, & Utgard, 2009). Foley, D., McKenzie, G. D., Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.). Reprinted by permission of Pearson Education, Inc. Geology 207: Introduction to Environmental Geology 7

(Revision 4) Figure 5.2. US population and flood impacts in billions of dollars, by decade. Foley, D., McKenzie, G. D., Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.). Reprinted by permission of Pearson Education, Inc. Figure 5.3. Variation in discharge/area ratio or flood intensity with drainage-basin area. Foley, D., McKenzie, G. D., Utgard, R. O. (2009). Investigations in Environmental Geology (3rd ed.). Reprinted by permission of Pearson Education, Inc. Geology 207: Introduction to Environmental Geology 8