Chapter 2: Characterization of Riparian Areas

Regions of Arizona

Arizona can be divided into three regions: Basin and Range, Central Highlands and Colorado Plateau. In each region, there is a broad range in the characteristics of drainage networks and riparian areas, which are generally controlled by topography and underlying geology.

 

  1. The Basin and Range is the desert region in southern and western Arizona. This region is characterized by numerous mountain ranges separated by lower elevation basins. Over time, drainage networks have developed over both alluvial fans and valley fills. Although the channels are generally dry, they can often be spotted as ribbons of green vegetation crossing the landscape. Rivers, such as the San Pedro, flow through the low lying basins.

  2. Figure 2.2. The three major regions
     of Arizona: Basin and Range, Central
    Highlands and Colorado Plateau
    The Central Highlands, occupying the mountainous region in central Arizona, receives relatively high rainfall, and has many small streams and lakes. The valleys are small and drained by relatively steep channels that convey flash floods which are characteristic of these streams.  Many of the mountains are surrounded by alluvial fans that lead to lowland valleys.through which the Colorado River flows.
  3. The Colorado Plateau contains flat-topped mesas, cliffs, water-carved badlands, and wind swept deserts. The prominent geologic feature is the Grand Canyon, through which the Colorado River flows. This region contains many ephemeral stream channels that flow only in response to summer thunderstorm rainfall.