Querying flow information
In nhdR: Tools for Working with the National Hydrography Dataset

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

Let's get some flow data for the NHDPlus subset included with nhdR package. Our goal is to adjust the color and size of each reach by their average flow.

library(nhdR)
library(dplyr)
library(ggplot2)
library(sf)

ggplot() +
  geom_sf(data = gull$sp$NHDWaterbody) +
  geom_sf(data = gull$sp$NHDFlowLine)

gull_sf <- gull$sp$NHDFlowLine

NHDPlus includes two estimates of flow:

Enhanced Unit Runoff Method (EROM)

eromflow  <- nhd_plus_load(4, "EROMExtension", "EROM_MA0001") %>%
  filter(ComID %in% gull$sp$NHDFlowLine$COMID) %>%
  select(ComID, Q0001F)

gull_sf <- left_join(gull_sf, eromflow, by = c("COMID" = "ComID"))

Vogel Flow Estimation

vogelflow  <- nhd_plus_load(4, "VogelExtension", "vogelflow") %>%
  filter(COMID %in% gull$sp$NHDFlowLine$COMID,
    MAFLOWV != -9999.00000)

gull_sf <- left_join(gull_sf, vogelflow, by = "COMID")

Visualization

# gull_sf <- dplyr::select(gull_sf, -Q0001F:-MAVELV)
gull_sf <- gull_flow

gull_sf <- dplyr::filter(gull_sf, !is.na(Q0001F))
gull_sf %>%
  ggplot() +
  geom_sf(data = gull$sp$NHDWaterbody) +
  geom_sf(aes(color = gull_sf$Q0001F), size = gull_sf$Q0001F / 20) +
  labs(color = "EROM Flow (cms)")

gull_sf <- filter(gull_sf, !is.na(MAFLOWV))
gull_sf %>%
  ggplot() +
  geom_sf(data = gull$sp$NHDWaterbody) +
  geom_sf(aes(color = gull_sf$MAFLOWV), size = gull_sf$MAFLOWV / 20) +
  labs(color = "Vogel Flow (cms)")