TITLE:
Mapping Mountain Front Recharge Areas in Arid Watersheds Based on a Digital Elevation Model and Land Cover Types
AUTHORS:
E. E. Bowen, Y. Hamada, B. L. O’Connor
KEYWORDS:
Water Resources, Arid Environment, Groundwater Recharge, Mountain Front, GIS
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.8,
June
19,
2014
ABSTRACT:
A recent
assessment that quantified potential impacts of solar energy development on
water resources in the southwestern United States necessitated the development
of a methodology to identify locations of mountain front recharge (MFR) in
order to guide land development decisions. A spatially explicit, slope-based
algorithm was created to delineate MFR zones in 17 arid, mountainous watersheds
using elevation and land cover data. Slopes were calculated from elevation data
and grouped into 100 classes using iterative self-organizing classification.
Candidate MFR zones were identified based on slope classes that were consistent
with MFR. Land cover types that were inconsistent with groundwater recharge
were excluded from the candidate areas to determine the final MFR zones. No MFR
reference maps exist for comparison with the study’s results, so the
reliability of the resulting MFR zone maps was evaluated qualitatively using
slope, surficial geology, soil, and land cover datasets. MFR zones ranged from
74 km2 to 1547 km2 and accounted for 40% of the total
watershed area studied. Slopes and surficial geologic materials that were
present in the MFR zones were consistent with conditions at the mountain front,
while soils and land cover that were present would generally promote
groundwater recharge. Visual inspection of the MFR zone maps also confirmed the
presence of well-recognized alluvial fan features in several study watersheds.
While qualitative evaluation suggested that the algorithm reliably delineated
MFR zones in most watersheds overall, the algorithm was better suited for
application in watersheds that had characteristic Basin and Range topography
and relatively flat basin floors than areas without these characteristics.
Because the algorithm performed well to reliably delineate the spatial
distribution of MFR, it would allow researchers to quantify aspects of the
hydrologic processes associated with MFR and help local land resource managers
to consider protection of critical groundwater recharge regions in their
development decisions.