Laserfiche WebLink
<br />1\.' ~'"'I!n-'.l'" <br />i... ~ '-J V <br /> <br />IMPACTS ON PEOPLE <br /> <br />17 <br /> <br /> <br />Figure 8. Stunted ears of corn caused by drought in Midwest. Photo by R. J. Modersohn, <br />Des Moines Sunday Register. <br /> <br />Recent research by the U.S. Forest Service <br />has shown that another effect of forest fires, <br />at least in chaparral, is the formation of <br />non wettable or water repellent soils. When <br />chaparral plants and the litter on the ground <br />are burned, a complex of waxlike substances is <br />pr'oduced which tends to coat the soil particles <br />and makes them hard to wet. The fire <br />vaporizes these substances, and the gases that <br />are heavier than air sink into the soil layer <br />wher'e they cool enough to recondense and <br />again coat the soil particles. This second <br />process mal<es soils that formerly were only <br />hard to wet virtually waterproof. If the water <br />cannot enter the soil, it must run off; there- <br />fore, the flood potential is increased (Wells, <br />1978). <br />Another long term effect of the drought is <br />the damage to timber and other trees from <br />insects, disease, and smog. Vegetation under- <br />goes additional stress when it does not receive <br />some minimum amount of moisture 01' does not <br />receive it at the proper time to foster growth. <br /> <br />Therefore, vegetation is more susceptible to <br />deleterious influences because of a drought. <br /> <br />Water QUality <br /> <br />Whenever streamflow falls below threshold <br />amounts, water-quality problems can be ex- <br />pected soon thereafter. The inability of low <br />stream flows to flush and dilute contaminants <br />in stream channels may let concentrations <br />from waste diseharges increase to the point <br />that the water is not usable. Higher than usual <br />concentrations of dissolved solids, one of the <br />indexes of water quality, occurred in North <br />and South Dakota, western Colorado, and Ohio. <br />Both natural sources and pollutants contri- <br />buted to the high concentrations. <br />The lower the flow for a prolonged period, <br />the less water there is to absorb wastes that <br />demand oxygen. A decrease in dissolved- <br />oxygen concentrations, called an oxygen sag, <br />can cause unpleasant odors and fish kills and <br />will reduce the ability of a stream to purify <br />