ABSTRACT
This chapter uses examples of hazards from the southwestern United States with a focus on the authors' experiences in Arizona to illustrate the array of hazards that may be present and affect urban and landscape design. The statistical concept of stationarity holds that the moments of a time series are temporally invariant; hydrologic nonstationarity occurs when the mean and (or) the variance of flow or flood magnitude changes with time (e.g., has a trend or fluctuation). Careful consideration should be given to the potential for debris flows upslope of subdivision development when hydrologic design is used for constructed drainage channels to mitigate the potential for channel aggradation, either from debris flows or the typical processes that deliver sediment from headwaters to terminus in ephemeral streams. In many cases, human activities can cause hazards of nature by disrupting the natural hydrologic, geologic, or climatic processes.
