---
title: "Querying flow information"
author: "Jemma Stachelek"
date: "`r Sys.Date()`"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Querying flow information}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include = FALSE}
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. 

```{r message=FALSE, warning=FALSE}
library(nhdR)
library(dplyr)
library(ggplot2)
library(sf)
```

```{r }
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)

```{r eval=FALSE}
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

```{r eval=FALSE}
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

```{r echo=FALSE}
# gull_sf <- dplyr::select(gull_sf, -Q0001F:-MAVELV)
gull_sf <- gull_flow
```

```{r }
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)")
```
