Fig 1.
Locations of selected National Park Service (NPS) units in the State of California include mountain, arid, and coastal climate types (from top, clockwise): Redwood National Park (REDW), Lassen Volcanic National Park (LAVO), Yosemite National Park (YOSE), Sequoia & Kings Canyon National Parks (SEKI), Death Valley National Park (DEVA), Joshua Tree National Park (JOTR), Channel Islands National Park (CHIS), Pinnacles National Park (PINN), and Point Reyes National Seashore (PORE).
Base layers source: Esri. “Light Gray Canvas Base” [vector]. Scale Not Given. “World_Basemap_v2”. Oct 26, 2017. https://www.arcgis.com/home/item.html?id=291da5eab3a0412593b66d384379f89f. (August 4, 2022).
Fig 2.
Mean visitation and 50% variance (+/-25% of raw visitation data closest to the mean, 1980–2019) for each National Park Service (NPS) unit in California by seasonal climate type: a) mountain, b) arid, and c) coastal. Note: Lassen Volcanic and Pinnacles both have a window of variance that is too narrow to be visible. Visitor data source: Integrated Resource Management Applications (IRMA), National Park Service, 2022.
Table 1.
National Park Service (NPS) units by climatic type, average annual visitors, and freshwater-dependent activities.
Visitor data were collected from the Integrated Resource Management Applications interface (National Park Service 2022) and water-dependent recreational activities were synthesized from each park’s official website.
Fig 3.
Departures in annual visitation totals for the nine different National Park Service (NPS) units by drought status reflected by summer Palmer Drought Severity Index (PDSI) during 1980–2019.
Statistically significant (p< 0.05) differences are denoted by white x symbols.
Fig 4.
Average monthly visitation by drought category at nine National Park Service (NPS) units in California.
Months where average visitation was significantly (p< 0.05) different for a given drought category than all other years are denoted by a colored dot.
Fig 5.
Average monthly visitation expressed as a departure from 1980–2019 average by drought category at nine National Park Service (NPS) units in California.
Months where average visitation was significantly (p< 0.05) different for a given drought category than all other years are denoted by a colored dot.
Fig 6.
Matrix of Pearson’s correlations between detrended seasonal park visitation and seasonal drought indicators during 1980–2019 across the nine national parks in California.
The correlation considers the Palmer Drought Severity Index (PDSI), snow water equivalent (SWE), soil moisture (SM), evaporative demand drought index (EDDI), Standardized Precipitation Index (SPI), and Standardized Precipitation Evapotranspiration Index (SPEI). Correlations that are statistically significant (p< 0.05) are denoted by an x. For aid in visualization, the sign of the correlation for EDDI is reversed. DJF, MAM, JJA, and SON refer to combinations of months, beginning with December, January, and February, and continuing with March and so on in successive monthly order.