Environmental monitoring is one of the primary means to ensure that impacts associated with renewable energy development are minimized. One critical aspect of water resources monitoring is the study of surface hydrologic processes — flow conveyance, sediment transport, and groundwater recharge — associated with intermittent and ephemeral streams.
Surface hydrology plays an important role in local ecosystems and water availability for human use, which is particularly critical for arid environments. Knowledge about ephemeral streams is the key to understanding the hydrologic cycle and how it influences the abundance and distribution of wildlife habitats in arid regions. However, quantifying these surface hydrologic processes (and how surface disturbances affect them) is challenging, because runoff events in arid and semi-arid landscapes are episodic. In addition, no established methods are available for accurately mapping and characterizing the functionality of ephemeral streams and channel networks in desert regions, largely because of their dynamic nature over large spatial and temporal scales, in combination with complex topography and harsh environmental conditions.
Although remote sensing is an effective means of collecting data and obtaining information for large, inaccessible areas, conventional techniques that rely on two-dimensional spectral information or are based solely on surface models are inadequate for extracting highly heterogeneous features that differ very subtly from the surrounding environment. To overcome these challenges, we have been developing a novel remote sensing approach for characterizing surface hydrologic features by detecting and mapping ephemeral channel locations and characteristics for a study watershed in a desert region of southern California. These efforts include characterizing vegetation, soil surface properties, and micro-topography by integrating information about spectral properties (or color) with relationships between ephemeral channels and their surrounding environment. This reliable, cost-effective method for mapping ephemeral channel networks is suitable for long-term environmental monitoring in arid environments.