Riparian zones are areas bordering rivers and washes where the vegetation is dependent on the presence of groundwater. Riparian zones are nature’s water filter for our watersheds. Arizona riparian areas are less than 0.4% of Arizona's total area.
- Subflow – Water that slowly finds its way through the sand and gravel constituting the bed of the stream, or the lands under or immediately adjacent to the stream. Subflow is the area where groundwater meets the surface stream. In Arizona water law subflow waters are considered to be surface water not groundwater.
- Stream channel – the stream channel is where the sediment and surface water flow. It is constantly changing based on the amount of sediment (called sediment load), vegetation in and around it, and the amount of flow in the rivers.
- Losing stream – The stream shown here, like many desert streams, is a losing stream. This means it is losing water on the surface as it flows downstream. The water is not really lost though, it is soaking into the ground and recharging the local groundwater. This happens because the water table is below the bottom of the stream channel.
- Groundwater well – Groundwater wells are sunk into the ground and pump water from the aquifer (an area of water mixed with sand and/or gravel under the surface). If more water is pumped from the well than is replaced by groundwater flowing into the area, a cone of depression develops. If this well is close to a stream this cone of depression can expand toward the river and will eventually “take” the water from the stream. Many desert streams no longer flow on the surface because of wells near streams.
- Riparian area - Riparian areas consist of the vegetation that depends upon flows in the stream and shallow groundwater (subflow). Adjacent upland vegetation in contrast survives on rain and moisture in the soil alone. Riparian areas include trees, shrubs, grasses, and sedges. Vegetation in the riparian area contributes shade, food, and shelter for aquatic organisms in the stream and is home to many animals that move between land and water, such as mammals, amphibians, birds, and insects.
- Upland areas – Upland areas are the higher ground where the stream does not flood. In desert systems the vegetation in upland areas survives on rain and the moisture in the soil alone.