GEOSS Water Services for Data and MapsCommunity RecommendationsDavid K. Arctur, Project Lead, GEOSS AIP-6 Water SBA david.arctur@utexas.eduUniversity of Texas at AustinOpen Geospatial Consortium (OGC)

Presented at GEO X Plenary & Ministerial SummitGeneva, SwitzerlandJanuary 2014

Purpose

In conducting AIP-6 Water SBA, we wished to identify the “best practices”, exchange standards, and other conventions needed for national and regional water agencies to effectively federate their data services.

This is a story about millions of small datasets:each with a time series of a variable at a point location

Water Quantity

Rainfall

… continuing and extending work demonstrated at theGEO IX Plenary in Brazil, 2012

Step 1: Search for a specific web map of stream gauges

Step 2: Examine the GEOSS registry metadata for the web map

Step 3: Follow the link to the web map

Click to add layers

Water Data Maps: Global Stream GaugesNot just seeing data providers’ bounding boxes, but actual locations of specific data… (Esri ArcGIS Online web map viewer)

http://bit.ly/19fUSPY

1. WMO GRDC (gauge descriptions only, no water data)2. Kisters GRDC (WaterML 2 data for OGC Surface Water IE) 3. USGS NWIS (most have real-time data)4. Mexico (some with historical data, hosted by Univ of Texas)5. Dominican Republic (historical data hosted by BYU)6. Italy & New Zealand (real-time data, developed for AIP-6)

Gauge descriptionand data links…

For quick overview

For easy analysis

WaterML for full details

WaterML 2.0

Document metadata

Observation description- Phenomena time- Result time- Procedure- Observed property- Feature of interest- Result

- Time series metadata- Time series data

Time series data, cont’d

Recommendation 1: Use OGC WaterML 2• Federation of regional & national water data is much easier with

community adoption and support for data exchange standards & practices

• WMO and OGC are developing international standards for hydrologic information: WaterML 2 is the preferred encoding– Part 1: Time series (OGC adopted; WMO pending)– Part 2: Ratings, gaugings and cross-sections (for determining

flow volume as function of stream depth and streambed conditions; in development)

– TBD: Sampled observations; Forecast-time representations

Recommendation 2: Use OGC WFS for feature layer of water data sites

GEOSS Search

Web Map Viewer

WFSNew Zealand gauges(HRC Hilltop host)

WFSItaly gauges

(ISPRA host)

WFSGRDC gauges(Kisters host)

One WFS service per data layer and/or producer

Mapping this feature layer enables direct visualization of the data to support interaction with it.

Recommendation 3: Water Map Service GuidelinesThere needs to be a consistent way of describing water data time series, that would be followed by data producers and software developers.

With this project we are defining a core set of feature attributes which characterize time series:

– WaterMLURL for a REST call to a data service endpoint, that enables a time series to be queried from this location.

– GraphURL and DownloadURL for graphing or downloading the data, if available.– BeginDate of the data (the time of first information, using ISO 8601 time format).– EndDate of the data (make Null if this is current time).– Descriptor – text descriptor of this feature (e.g. Site name for gaging station, COMID

for NHDPlus, etc)– Source – text field that specifies the source of the data e.g. USGS, etc.

• If the EndDate field is empty (null), this means the data service is a near-real-time feed, not just an historical dataset.

• The WaterML time series data is served by OGC Sensor Observation Service (SOS). • WMO/OGC Hydrology Working Group is working on unambiguous conventions for

data service REST calls – keep track of this

Recommendation 4: Use OGC SOS 2 as the web data service for WaterML 2

Web Map Viewer

SOSGRDC WaterML2

(Kisters host)

WOFItaly WaterML1.1

(ISPRA host)

SOSNew Zealand WaterML2(HRC Hilltop host)

But be prepared for the many sites running CUAHSI WaterOneFlow (WOF) web service for WaterML 1.x data

Summary of web services

(CSW)Catalog of

Data Providers’ gauge layers

(WFS)Map of gauges (one layer

per observed property) for one Data Provider

(SOS)Data service

for time series at one gauge

3Request map from each

Data Provider about [observed property]

5Request data service

for time series of selected gauge

6Return time series

data or graph (WaterML, CSV)

2Return list of Data

Providers’ map layers

1Request data about [observed property]

4Return gauge locations as a

map layer (GML SF)

CommunityWeb PortalDiscovery, Access

and Visualization

Recommendation 5: Data providers should manage WFS time series descriptions in a catalog registry

• Each data provider could install and manage a catalog registry of relevant time series descriptions (WFS feature layers)

OR… • Use an established community catalog for that purpose

(eg, CUAHSI HydroServer)

• This catalog should itself be registered with GEOSS.

Example: Canadian Monitoring Network

• This data provider has registered its Kisters precipitation feeds in a GIcat registry installed by the data provider.

• This GIcat service’s CSW interface is registered in GEOSS.

• This enables distributed search for a single known monitor site via GEOSS Portal…

Public Web Map Viewer (registered in GEOSS)for Global Precipitation Gauges

http://bit.ly/19fV1Tz

Water Data Maps: Canada Precipitation Gauges

Water Data Maps: Canada Precipitation Data

Register with GEOSS to promote interdisciplinary discovery

By registering the community portal and its catalog in GEOSS, interdisciplinary users can more easily discover these resources

CommunityWeb PortalDiscovery, Access

and Visualization

(CSW)Catalog of

Data Providers’ gauge layers

(WFS)Map of gauges (one layer

per observed property) for one Data Provider

(SOS)Data service

for time series at one gauge

www.geoportal.org GEOSS

Summary of Recommendations

1. Use OGC WaterML 2 for water-variable time series data (streamflow, precipitation, runoff, etc).

2. Use OGC WFS for a feature layer of water data sites; one WFS service per data layer / producer.

3. Use consistent & minimal subset of time series description fields in the WFS data service.

4. Use OGC SOS 2 as the web data service for WaterML 2, but be prepared for the many sites running CUAHSI WaterOneFlow (WOF) web service for WaterML 1.x data, and even WFS for WaterML time series data.

5. Each data provider could install and manage a catalog registry of relevant time series descriptions (WFS feature layers), or use an established community catalog for that purpose (eg, CUAHSI HIS Central). This catalog should itself be registered in GEOSS.

Future Work: AIP-7 End-user focus• Develop more application-oriented scenarios around flood, drought, and

water quality monitoring and prediction. Technological focus• Support discovery and access through GEOSS to additional water resource

variables, such as stream depth, precipitation, water quality, soil moisture, evapotranspiration, total water storage.

• Promote international conventions for the specific data exchange requests (i.e., allowed parameters and values) between clients & data servers.

• Provide cloud-based data services to reduce equipment, software, and training needs for developing countries.

Institutional focus• Coordinate with IGWCO and WMO so this development work will become

institutionalized by the appropriate international authoritative agencies. • Work with developing countries to improve readiness to share national data

David K. Arcturdavid.arctur@utexas.eduUniversity of Texas at AustinOpen Geospatial Consortium (OGC)

Thank you!