OCR Text |
Show FLOOD CONTROL A major part of the Region's presently developed urban area and productive cropland is on lands subject to periodic flooding. Most land having topography suitable for general development within the Region is subject to flooding whether near a defined stream or not. It is expected that mos-fc future development, whether urban or agricultural, will need some degree of flood protection. In 1965, there were approximately 164,000 acres of urban land and over one million acres of cropland sub- ject to flooding within the Region. In addition, about k.3 million acres of fores-fc and rangeland are subject to flooding. Flood damages are classified as either downstream or upstream. In general, downstream flood damages are those occurring on the main stems and majox tributaries, and upstream flood damages are those experienced on the smaller tributaries (having drainage areas of less than 250,000 acres). Based on the 19&5 level of flood plain development and protection, average annual flood damage within the Region is estimated to be about $41 million. Of this amount, approximately $22 million is agricultural damage and $19 million is nonagricultural damage. Of the total damage, 30 percent is in downstream areas and 70 percent is in upstream areas l/. Past trends have shown that flood damages generally increase when there is a rise in economic development. Virtually all economic projections indicate continued development of land in the Lower Colorado Region. With pro-tection at the 1965 level, the expansion of the economy and projected growth in the area subject to flooding would increase total flood damage to $310 million by 2020 as shown in Figure 13. The annual agricultural damages would increase from $21 million to $6l million and the nonagricultural damages would increase from $20 million to $2^9 million. The nonagricultural damages include $13 million urban damages in 1965 and $201 million in 2020. 1/ (a) This presentation of flood damage data by upstream-downstream areas in no way determines the agency responsible for the solution of tlie flood damage problems; and (b) data presented include major urban damages in upstream areas. 76 |