Archive for the ‘Hydro’ Category

Space, Time & Hydrography


ESRI has developed some useful hydrography tools for Spatial Analyst. Maybe I’m missing something, but I don’t see any tools for cleaning up gaps and spikes in flow (time series) data. Water flow telemetry can contain a lot of subtle noise that should be cleaned before used in models.

I’m writing some tools to clean up time series data. It seems like some of the concepts of the 2 dimensional kernel used by spatial analyst could be generalized (and simplified) to work with one dimensional (time series) data. This would allow me to resample data collected at odd intervals into an evenly spaced sampling scheme. Lots of the operators available for rasters seem applicable to time series: resampling, overlays, convolution.

There appear to be a lot of tools out there written for stock market analysis, but they don’t seem concerned with cleaning up errors.


Does the World Really need more Lerts?

Be alert. The world needs more lerts.

Or does it?

The NWS sent this rather startling “graphicast” Friday. I live under the second “a” in Area. As of Monday, I’ve gotten an inch of rain. Credibility diminishes when alerts are issued for events that never occur.

While graphicasts are better than the old all-caps alerts, they still miss the mark.

We need alerts that are more specific. Here in the hill country, the primary risk is at low water crossings – not large rectangular areas. The locations of these crossings are known. Models can predict flooding at these crossings, what is needed is a system to broadcast alerts to subscribers.

“Turn around, don’t drown” is a catchy slogan, but if you’re trapped between two low water crossings the best thing to do is sit and wait.

I’ve mentioned before how Google could do something similar for traffic alerts. This same thing could be done for flood alerts.

I would like to receive alerts via IM on my cell phone when any water crossing along the path I plan to travel is expected to flood. Alternate route directions would be nice too.

GIS Helps Manage Water Rights

Here in South Texas everyone talks about a looming water crisis, but few are doing anything about it.

An exception seems to be Guadalupe County Groundwater Conservation District where they are using GIS to stake a claim on groundwater.

If the county moves forward with the idea, it could be a groundbreaking option for Texas counties, cities and municipal utility districts to gain pumping rights from groundwater districts and make money by leasing the water rights for property the county owns, including long stretches of county roads.

They seem to be assuming uniform thickness of the water bearing sand formation. I wonder if people will demand a more accurate survey of subsurface water.