An introduction to hydroscoper

What is Hydroscope?

Hydroscope is the Greek National Data Bank for Hydrological and Meteorological Information, a result of long-standing efforts by numerous Greek scientists in collaboration with various companies and associations. It was implemented in three phases, funded by the Ministry of Development, the Ministry of Environment and Energy and the European Union.

This National Data Bank provides several data sources from various organisations via a web interface. Each participating organisation keeps its data on its own server using a database system for the storage and management of information. These organisations are:

• Ministry of Environment and Energy.
• Ministry of Rural Development and Food.
• National Meteorological Service.
• National Observatory of Athens.
• Greek Prefectures.
• Public Power Corporation.

The above data are structured as tables and space separated text files, but are in Greek, thus limiting their usefulness. Another issue with Hydroscope is the lack of comprehensive look-up tables about the available data, which are spread across many different databases.

What does hydroscoper?

hydroscoper provides functionality for automatic retrieval and translation of Hydroscope’s data to English. The main functions that can be utilized is the family of functions, get_stations, get_timeseries, get_data, etc., to easily download Hydroscope’s data as tibbles.

The package covers Hydroscope’s data sources using the Enhydris API. The Enhydris database is implemented in PostgreSQL and details about the database can be found here, and about the Web-service API here.

Data sources

• Ministry of Environment and Energy, National Observatory of Athens and Greek Prefectures, http://kyy.hydroscope.gr/.
• Ministry of Rural Development and Food, http://ypaat.hydroscope.gr.
• National Meteorological Service, http://emy.hydroscope.gr.
• Greek Public Power Corporation, http://deh.hydroscope.gr.

Note that:

1. Only the two Ministries allow to download time series values freely.
2. ypaat, emy and kyy sub-domains are maintained by the National Technical University Of Athens and these servers work seamlessly.
3. deh sub-domain is maintained by the Greek Public Power Corporation and occasionally the server is down.

Example

This is a basic example which shows how to get the stations’ and time series’ data from the Hydroscope’s Ministry of Environment and Energy database, http://kyy.hydroscope.gr/.

Load libraries:

library(hydroscoper)
library(ggplot2)
library(tibble)

We will use the package’s data stations and timeseries, to reduce the time needed with data munging. We can subset the station’s data for the kyy sub-domain with:

# load data
data("stations")

# subset stations data
kyy_stations <- subset(stations, subdomain == "kyy")

# view kyy stations
kyy_stations
#> # A tibble: 425 x 9
#>    station_id name    water_basin  water_division owner longitude latitude
#>         <int> <chr>   <chr>        <chr>          <chr>     <dbl>    <dbl>
#>  1     501032 AG. BA~ "KOURTALIOT~ GR13           min_~      NA       NA  
#>  2     200246 GEPH. ~ "ALPHEIOS P~ GR01           min_~      22.0     37.5
#>  3     200237 TROPAIA "ALPHEIOS P~ GR01           min_~      22.0     37.7
#>  4     200231 BYTINA  "ALPHEIOS P~ GR01           min_~      22.2     37.7
#>  5     200200 LYKOUR~ "ALPHEIOS P~ GR01           min_~      22.2     37.9
#>  6     200236 MEGALO~ "ALPHEIOS P~ GR01           min_~      22.1     37.4
#>  7     200244 ODOG. ~ "REMA CHORA~ GR01           min_~      21.8     37.0
#>  8     200204 TRIPOT~ "ALPHEIOS P~ GR01           min_~      21.9     37.9
#>  9     200198 KASTEL~ "ALPHEIOS P~ GR01           min_~      22.0     37.9
#> 10     200239 PERDIK~ "ALPHEIOS P~ GR01           min_~      22.0     37.7
#> # ... with 415 more rows, and 2 more variables: altitude <dbl>,
#> #   subdomain <chr>

Let’s plot these stations using the package’s dataset greece_borders.

ggplot() + 
  geom_polygon(data = greece_borders,
               aes(long, lat, group = group),
               fill = "grey",
               color = NA) +
  geom_point(data = kyy_stations,
             aes(x = longitude, y = latitude),
             color = "#E64B35FF") +
  coord_fixed(ratio=1) +
  theme_bw()
#> Warning: Removed 11 rows containing missing values (geom_point).

To get the time series’ data for the station 200200 (http://kyy.hydroscope.gr/stations/d/200200/) we can use:

station_ts <- subset(timeseries, station_id == 200200)
station_ts
#> # A tibble: 4 x 8
#>   time_id station_id variable timestep units start_date end_date subdomain
#>     <int>      <int> <chr>    <chr>    <chr> <chr>      <chr>    <chr>    
#> 1     761     200200 wind_di~ <NA>     °     1948-01-0~ 1997-07~ kyy      
#> 2      56     200200 precipi~ 30_minu~ mm    1985-05-0~ 1997-01~ kyy      
#> 3     760     200200 snow     daily    mm    1948-01-0~ 1997-07~ kyy      
#> 4     759     200200 precipi~ daily    mm    1953-03-0~ 2011-06~ kyy

We can download the station’s precipitation time series 56 (http://kyy.hydroscope.gr/timeseries/d/56/):

ts_raw <- get_data(subdomain = "kyy", time_id = 56)
ts_raw
#> # A tibble: 147,519 x 3
#>    date                value comment
#>    <dttm>              <dbl> <chr>  
#>  1 1985-05-06 08:00:00     0 1      
#>  2 1985-05-06 08:30:00     0 1      
#>  3 1985-05-06 09:00:00     0 1      
#>  4 1985-05-06 09:30:00     0 1      
#>  5 1985-05-06 10:00:00     0 1      
#>  6 1985-05-06 10:30:00     0 1      
#>  7 1985-05-06 11:00:00     0 1      
#>  8 1985-05-06 11:30:00     0 1      
#>  9 1985-05-06 12:00:00     0 1      
#> 10 1985-05-06 12:30:00     0 1      
#> # ... with 147,509 more rows

Let’s create a plot:

ggplot(data = ts_raw, aes(x = date, y = value))+
  geom_line()+
  labs(title= "30 min precipitation", 
       subtitle = "station 200200",
       x="Date", y = "Rain height (mm)")+
  theme_classic()