Location of the highest concentration of advection fogs on the Central Coast of Peru between the years 2000 -2014, using satellite images, as potential freshwater resources

Abstract:

Advection fogs are alternative freshwater resources not yet exploited in the geographical region of the Peruvian coast. The potential of fogs as a freshwater resource has been demonstrated, in several countries, through the accumulation of water by fog catchers. The fogs supply water to the coastal lomas where the areas with the most vegetation correspond to places with greater availability of water from the fog, since there is no rainwater, so to find the places with the highest concentration of the fogs have to analyze the physical characteristics of the lomas.

One of the most important characteristics of the vegetation of the hills is that altitude is the most important predictor of its plant richness, due to the increase in water condensation with altitude, until reaching the thermal inversion zone, so the higher humidity is below this inversion zone. Two types of satellite images are used to evaluate this vegetal wealth: The Normalized Vegetation Index (NDVI) and the Digital Elevation Model (DEM).

With satellite images, the central coast of Peru is delimited and the vegetation produced by rivers and cultivation areas is discriminated to obtain a map with only natural vegetation of lomas, then topographic profiles are created that cross the most important lomas of the coast. The degree of correlation between the NDVI and the altitude is found.

The analysis of this correlation gives several results. The most important of which is obtaining the NDVI threshold of lomas formation on the central coast of Peru, equal to 0.26, located at an average height of 259 ± 97.27 masl.

Another important result is the maximum height average of the lomas, equal to 1033 ± 100.06 masl, and between these two limits it is found that the greatest development of the vegetation occurs at an average height of 644.6 ± 101.8 masl. At this height where the highest concentration of advection fogs is, It’s where you can install fog catchers to collect water.