Tag: Texas

NGS revises NOAA report on working in the modernized NSRS
The National Geodetic Survey (NGS) has revised an important technical document on the modernized National Spatial Reference System (NSRS). Zilkoski explores a use case on flood mapping, discussing an Elevation Certificate example, Flood Insurance Rate Map and Flood Insurance Study. NGS has scheduled a webinar for April 8 to discuss the four use case examples.

In February 2021, the National Geodetic Survey (NGS) revised NOAA Technical Report NOS NGS 67 Blueprint for the Modernized NSRS, Part 3: Working in the Modernized NSRS. Users can download the publication. See the box titled “NOAA Technical Report NOS NGS 67.”

NOAA Technical Report NOS NGS 67. (Image: NGS)

On March 11, NGS held a webinar describing the revised document (see box titled “Working in the Modernized NSRS”). Download a video of the webinar and the presentation.

Working in the Modernized NSRS. (Image: NGS}

The revised document added four use cases to describe how someone might access and use the NSRS in the future:
- Use Case 1: Flood Mapping,
- Use Case 2: Passive Control for a Multi-year Corridor Project,
- Use Case 3: Transitioning Data to the Modernized NSRS, and
- Use Case 4: Leveraging the Modernized NSRS for Airport and Other Infrastructure Monitoring.
The box titled “Major Changes to NOS NGS 67” highlights the changes in the February 2021 revised version.

Major Changes to NOS NGS 67. (Image: NGS)

This column will highlight one of the four use cases: “Use Case 1: Flood Mapping.” The case study discusses the Elevation Certificate (CE) example, Flood Insurance Rate Map (FIRM), and Flood Insurance Study (FIS).

The following is the scenario that NGS considered in this use case:

“This use case’s examples are set in an imaginary flood-prone coastal community experiencing non-uniform ground subsidence at the watershed scale (see Figure 10). Although many areas are not subject to this level of vertical motion, the full benefits of NSRS modernization are most apparent in this context. We illustrate differences in the use of the NSRS of today and the modernized NSRS with two common NFIP workflows. First, we consider steps anticipated in the certification of NAPGD2022 elevations for a NFIP Elevation Certificate. Second, we step into the shoes of a FEMA Mapping Partner to examine the ways future NSRS tools support more accurate mapping in Flood Insurance Rate Map (FIRM) and Flood Information Study (FIS) updates.”

I think this is a good scenario to use to demonstrate the full benefits of the NSRS modernization in areas of subsidence, but I believe there are important issues that will need to be addressed before the implementation of NAPGD2022 in flood mapping projects. I will highlight some of these issues later in the newsletter. First, let’s look at NGS example.

As depicted in figure 10 in NOS NGS 67 technical document, the area has three difference subsidence rates (<0.1 cm/yr., 2 cm/yr., and 5 cm/yr.). See the box titled “Diagram of fictional case study location for Use Case 1.” As NGS stated in the document, “Although many areas are not subject to this level of vertical motion, the full benefits of NSRS modernization are most apparent in this context.”

This may not be the typical situation of a flood mapping project but it should be noted that this type of high individual rates and large relative rate differences has occurred in the Houston-Galveston, Texas, region (see the following publications):
NGS’s example illustrates differences in the use of the NSRS today and the future NSRS with two common National Flood Insurance Program (NFIP) workflows. The example addresses surveyors performing a FEMA Elevation Certification using NAPGD2022 elevations, and the ways future NSRS tools support more accurate mapping in Flood Insurance Rate Map (FIRM) and Flood Information Study (FIS) updates.

Diagram of fictional case study location for Use Case 1 (Figure 10), The arrows correspond to hypothetical rates of ground subsidence. (Image: NGS)

It should be noted that according to the September 27, 2017, Office of Inspector General Department of Homeland Security OIG-17-110 report, FEMA’s goal is to review flood maps every five years.

“According to the National Flood Insurance Reform Act of 1994, FEMA must assess the need to revise and update all floodplain areas and flood risk zones identified once during each 5-year period. Thus, valid miles will expire every five years if not assessed. Failure to assess an NVUE compliant mile within the 5-year window will result in the mile being re-categorized as “Unknown” in the Needs Database. Unknown miles have not been subjected to the validation process to determine whether they reflect the current flood risk or are in need of restudy. In 2009, FEMA set a goal to attain 80 percent NVUE by the end of fiscal year 2014.” — Excerpt from Department of Homeland Security OIG-17-110 report

The modernized NSRS will help facilitate meeting this goal. This is described in NGS’s use case example:

NFIP products will primarily utilize the official NSRS reference epochs

“As the NFIP is structured today, NFIP products will primarily utilize the official NSRS reference epochs. Additionally, some NFIP products such as the EC form itself, as well as guidance, and technical references for FIRM and FIS preparation would benefit from updates that reflect changes to the NSRS. While the time-dependency and incorporation of a gravimetric geoid model will manifest as improved risk assessment reliability in inundation map products, we notably anticipate that NSRS modernization will have a limited impact on the basic structure of most recommended workflows associated with the NFIP of today. The most significant development is therefore the opportunity for FEMA’s National Flood Mapping Program (NFMP) to increasingly leverage the new capabilities of the NSRS to ensure that current, accurate ground elevation data is used, and to better incorporate relevant flood control structure and future conditions mapping data to support decision-making beyond the NFIP. Details of how the modernized NSRS can help FEMA achieve broader NFMP objectives and opportunities for data-driven case studies to explore this are described at the end of the use case.”

So, what does this really mean? The document uses two diagrams to explain how the new NSRS would be used to estimate a height for a FEMA Elevation Certificate (see box titled “Figure 11 from Use Case 1”). The top cartoon labeled “Tie to Passive Control” describes the process being performed today. That is, a surveyor locates the two closest marks that have published orthometric heights, follows the appropriate surveying procedures to ensure that the marks have not moved since the last time they were leveled to, and then performs the appropriate procedures to obtain the height for the Elevation Certificate. Depending on the location of the published orthometric heights in the area of the structure, this process could be very expensive. The lower cartoon labeled “Tie to Active Control” describes the process that will be used in the modernized NSRS using NADGP2022 heights. The user would occupy a temporary mark near the structure with GNSS to obtain a NAPGD2022 orthometric height computed using the appropriate ellipsoid height and geoid height value, and then perform the appropriate leveling procedures to obtain the height for the Elevation Certificate. This process will provide the most up-to-date height in the area.

Figure 11 from Use Case 1. Cartoon of Elevation Certificate field surveys based on establishing a tie to the NSRS via passive control leveling (top panel) and via active control with GNSS (lower panel). (Image: NGS)

There is an issue that should be noted here: the temporary mark determined using active control may provide the most up-to-date height at a particular location but that height may not be consistent with the heights used to establish the Base Flood Elevation (BFE). At first, someone would say, that’s good because it’s indicating that the flood hydraulics have changed on the floodplain map. However, without performing a detailed height analysis in the region, the user won’t really know whether the BFE value should be updated based on the current changes in topography in the floodplain region. In other words, if the entire region has subsidence at the same rate then the relative height difference hasn’t changed, and the new starting height may not be consistent with the published BFE on the FEMA Floodplain Map. In most floodplain mapping regions, the changes in heights are probably less than the accuracy of the maps but using the height of a mark that is not consistent with the BFE could place a homeowner’s house incorrectly in a flood zone. A good surveying practice would include occupying several marks with GNSS (or leveling between marks) that were involved in the creation of the flood insurance study and the generation of the floodplain map to ensure that the height used on the Elevation Certificate is consistent with the BFE. This is a good procedure to use for the current NSRS as well as the modernized NSRS. However, this is not economically practical using the current NSRS but could be in the new NSRS which is a major benefit of the modernized NSRS.
So, let’s look at the Houston-Galveston region using the latest information available.

Download latest FEMA Flood Insurance Rate Map (FIRM). See box titled “Excerpt from FEMA FIRM Map Number 48201C0440N.”

Excerpt from FEMA FIRM Map Number 48201C0440N. (Image: FEMA)

According to the latest Flood Insurance Study (FIS), the heights used in the study were based on a 2001 adjustment performed by the county. You can download the FIS from FEMA Flood Map Service Center | Search All Products, 48201CV001G (fema.gov) and map1.msc.fema.gov.

I’d like to highlight a few statements in the FIS. First, the reports states that the FIS and DFIRM are referenced to the NAVD (2001 Adjustment). See the box titled “Page 111 from November 15, 2019 Flood Insurance Study 48201CV001G.” The report provides a link for users to obtain the latest vertical control data. Users can find information about the Harris County Floodplain Reference Marks here (See box titled “Harris County Floodplain Reference Marks.”) Users also can access the vertical control data at the county website.

Page 111 from Nov. 15, 2019, Flood Insurance Study 48201CV001G. (Image: FEMA)

Harris County Floodplain Reference Marks. (Image: Harris County Flood Control District)

The box titled “Snapshot of Vertical Control from Harris County Floodplain Reference Marks Website” depicts the location of one of the reference marks, denoted as 050190.

Snapshot of Vertical Control from Harris County Floodplain Reference Marks Website. (Image: Harris County Flood Control District))

Clicking on the datasheets link, provides the information about the floodplain reference mark in the Harris County Flood Control District’s system (see the box titled “Harris County Floodplain Reference Mark Datasheet”).

Harris County Floodplain Reference Mark Datasheet. (Image: Harris County Flood Control District)

It should be noted that the GNSS-derived orthometric heights were based on GEOID99 and the official hybrid geoid model published by NGS today is GEOID18. A GNSS-derived orthometric height computed using NGS’ webtool OPUS will use GEOID18 not GEOID99. The difference between GEOID99 and GEOID18 at this location is approximately 0.45 feet (0.138 meters). Users must ensure that they are using heights that are consistent with the BFE on the FIRM. The new NAPGD2022 will help to reduce issues associated with effects due to changes in geoid models.

Page 113 from the November 15, 2019 Flood Insurance Study 48201CV001G addresses the issues associated with riverine flood in the region. (See the box titled “Page 113 from November 15, 2019 Flood Insurance Study 48201CV001G.”) The highlighted sections basically state that subsidence within inland watersheds has little or no effect on flood depths when the entire watershed subsides at the same rate. However, it also states that differential subsidence can cause changes in flood depths. The report goes on to say that the “Harris County and Incorporated Areas are affected by wide-scale, uniform subsidence with minor differential subsidence within individual watersheds.” It also states that “The local effects of subsidence may be adequately addressed, in the short term, by assuming that BFEs subside by the same amount the ground subsides.” The Houston-Galveston, Texas, region is a very complicated area due to the differential subsidence and numerous individual watersheds.

Page 113 from November 15, 2019, Flood Insurance Study 48201CV001G. (Image: FEMA)

That said, let’s look some of the latest subsidence data in the region. The Harris-Galveston Subsidence District’s 2018 Annual Groundwater Report By Robert Thompson, William M. Chrismer, and Christina Petersen, PhD, P.E. provide some of the latest estimates of subsidence in the region. The box titled “HGSD Exhibit 18” depicts the locations of the GNSS sites used in the study. The plot provides the average compaction in centimeters over the past five years. The values range from 0.0 cm/year to greater than 2.5 cm/year.

HGSD Exhibit 18. This map shows the locations of the GPS sites throughout the area. The colored dots represent the average compaction over the past five years for each site, in centimeters. They range from 0.0 cm/year to greater than 2.5 cm/year. (Image: Harris-Galveston Subsidence District)

I used the information from Appendix B provided in the report to generate a few plots that show the estimate of subsidence in feet over 5 years. I’ve highlighted some marks that have large relative height changes. (Note: The units of the previous figure are centimeters; the units of the next several plots are feet.)

Estimate of Amount of Subsidence in 5 Years – Units: Feet. (Image: David Zilkoski)

The relative height change between the two marks PA01 and CFHS, which are about 1.5 kilometers (approximately 1 mile) apart, is 0.197 feet in only 5 years. (See the box titled “Estimate of Amount of Subsidence in 5 Years at Pam 1– Units Feet.”)

Estimate of Amount of Subsidence in 5 Years at Pam 1 – Units: Feet. (Image: David Zilkoski)

The estimated relative height change between mark PA46 and ROD1, which are about 8 kilometers (approximately 5 miles) apart, is 0.277 feet in five years. (See the box titled “Estimate of Amount of Subsidence in 5 Years at Pam 46 – Units: Feet.”)

Estimate of Amount of Subsidence in 5 Years at Pam 46 – Units: Feet.(Image: David Zilkoski)

The effect of these large relative differences may not have any effect on the BFE on a particular watershed. These subsidence estimates are at a specific mark so they only provide information at a particular location. The new NAPGD2022 along with NGS’s webtools will enable users to economically obtain current, accurate heights in the entire region. Leveraging the capabilities of the new NSRS will help facilitate the implementation of FEMA’s goal of assessing the need to revise and update all floodplain areas and flood risk zones identified once during each five-year period.

There’s one last item that I’d like to highlight in this newsletter. On March 12, NGS announced that they are suppressing height information in Southeast Texas. See the box titled “NGS Announcement to Suppresses Height Information for Southeast Texas” for more information.

This column highlighted the potential effects of subsidence on published heights in the Houston, Texas, region, which implies that most of the published heights based on older surveys in the region are not current or accurate.

NGS announcement to suppress height information for Southeast Texas. (Image: NGS)

According to the announcement, only 28 marks will have publicly available orthometric heights on NGS datasheets in Southeast Texas. This NOAA website provides more information. See the box titled “NGS Southeast Texas Orthometric Heights.”

NGS Southeast Texas Orthometric Heights. (Image: NGS)

I would encourage everyone to check out the website to obtain a better understanding of what this suppression of published heights means to their operations. Future newsletters will address the suppression of the orthometric heights in Southeast Texas, and how users can help densify the network and prepare for the new, modernized NAPGD2022. Again, a benefit of the new modernized NSRS will facilitate the establishment of consistent, accurate NAPGD2022 GNSS-derived orthometric heights.

Lastly, NGS is convening the 2021 Geospatial Summit on May 4 and 5. The 2021 Geospatial Summit will provide updated information about the planned modernization of the National Spatial Reference System (NSRS). Register here.
April 7, 2021
How GIS — and you — can aid in disaster response
Whether you are on the helping end of a disaster aiding in the rescue and recovery, or on the receiving end being aided, GIS is supercharging the rescue efforts.

How can I help you if I don’t know where you are?

Hurricane Harvey hits. The storm was worsening. Winds were sustained at over 120 mph. Landfall of Hurricane Harvey was expected in 48 hours. Worse, the storm was forecast to stall once overland creating the single worst rain event in United States history.

Texas Governor Greg Abbott encouraged people to evacuate, especially those in low lying areas. Mayor Turner had only hours to decide the possible fate of millions. Making the call not to evacuate a category 4 hurricane approaching the city could be political suicide. Consider the fallout after Hurricane Katrina. The models clearly showed the extent of flooding and how many people would be trapped in their cars on flooded roads.

“You cannot put 6.5 million people on the road,” said Houston Mayor Sylvester Turner. The mayor’s ultimate decision not to issue an evacuation declaration was based on geospatial models, and as devastating as they were, it showed a better outcome if everyone stocked up, stayed put, and helped each other out after the storm. At least by staying home we will know where people are after the storm.

Gov. Abbott fully mobilized the National Guard and another 30 state agencies responded to the crisis. U.S. Federal Emergency Management Agency (FEMA) calls to action went out to the Coast Guard and volunteer organizations. Small boats, raised axel trucks and Vietnam-era looking personnel carriers were brought in for support, along with helicopters, drones and search and rescue airplanes.

First responders were issued full body waders and foul weather gear. Thousands of hypothermia blankets were stockpiled and cargo trucks carrying food, water and cots headed south. Volunteers from the Cajun Navy, Team Rubicon, the Red Cross, Open Street Maps, Samaritan’s Purse and others positioned their able-bodied forces along the periphery of the storm’s path ready to move in as soon as given the word.

Thursday afternoon the winds and rains began getting increasingly worse. Darkness fell and by 10 p.m. the eye of the storm had made landfall. Rivers and streams began overflowing due in part to the storm surge moving waters upstream. Streets no longer drained the waters. The flooding continued to rise.

Tremendous thermodynamic forces. Hurricanes aren’t a single, solid storm, though they may look like it from satellite imagery. They are enormous atmospheric depressions like a hole formed in the sky and air masses from thousands of miles around rush in to fill the void. These converging air masses create immense thermodynamic forces extending outward from a central vortex in long sweeping radial bands like blades of an enormous turbine.

A hurricane is the cumulative fury of these destructive forces storm after storm after in rapid succession. Winds increase and decrease as the radial bands pass overhead becoming stronger and more constant as the eye approaches. Every plank, nail and screw is tested. Immense gusts like giant hammers breaks away loose thing. Strains of timber and steel shriek in the wind. In seconds sounds of groaning trees and the air fills with flying debris. Rain comes down in torrents.

But in between these spiral bands it slows, sometimes stopping all together, even sunshine or moonlight might break through, but to believe the storm is over would be wrong — maybe dead wrong. Another band will sweep in with gusting, howling wind, thick, heavy clouds and dark skies, and rain, more and more rain, and the rising waters turning into gushing floods. Moments of endless terror turn into hours, the waters rising higher ever higher.

Finally, 49 inches of rain and three days later the storm ended moving offshore. Its destruction shut down the fourth largest city in the United States.

“…Texans have suffered a great hardship, their warmth and resiliency is truly inspiring,” said Gov. Abbott. The overwhelming willingness of people and organizations to help once the storm passed brought its own challenges. A convergence of rescue and recovery teams began.

Leaders needed. It was obvious a coordinated effort needed to happen. Volunteers and organizations needed to work in unison. FEMA had to establish that order. The coordination center was formed, not unlike other disasters, but this time another dimension was added to it. FEMA was aware of social media’s ability to positively impact rescue operations tapping into briefly during Superstorm Sandy, the last large scale disaster to hit the United States, but FEMA lacked the necessary skills and expertise to capitalize on the technology.

It is times like these that the greatest of all resources is realized. When asked what is the greatest asset, the answers most often given are manpower, money, equipment or supplies; however, even if there are plenty of the above, it is quickly realized the greatest resource is leadership. In times of crises, normal authority is laid aside and given to those who can bring order to the chaos.

Christopher Vaughn, the geospatial information officer for FEMA, and Adrian Gardner, the chief information officer for FEMA, were those individuals stepping up to the task at hand. They understood getting better data faster and putting it into geospatial context held the answer. Once done that would be the foundational layer. All the other elements could then be added, like imagery, lots and lots of imagery, both before and after; and then overlay crowdsourced data.

Vaughn, working with his counterparts in the Department of Homeland Security, brought in Homeland Infrastructure Foundation Level Data (HIFLD) layers, along with the Civil Air Patrol and DigitalGlobe’s Open Data Program. Launched in 2017, the program provides before and after imagery. Vaughn understood that the citizen-as-a-censor model provided raw, real-time and relevant information. It had to be tapped into to get control of the rescue operations.

Sophia Liu, Ph.D., an Innovation Specialist and expert in crowdsource efforts was brought in from the United States Geographic Survey (USGS). Liu was the key to unlocking the crowd. She shared her greatest challenge was the misconceptions around the use of social media and an apprehension to using it without proper approvals from public relations. It took some convincing to change these mindsets.

What helped tip the scales in her favor was Hurricane Irma coming right on the heels of Hurricane Harvey and then Hurricane Maria. The disasters were coming in way too fast and the detractors were drowned out by the need for information. Once they saw the value of crowdsourcing, there was little resistance.

Challenges in Puerto Rico. The results spoke for themselves. In Puerto Rico, within only a few weeks of Hurricane Maria’s devastation, 1.4 million homes were analyzed for damage and 24,000 miles of roads were digitized through volunteer groups like GIS Corps and OpenStreetMaps.

One of the greatest challenges in Puerto Rico was the lack of street addresses. That is more common than one might realize. In many parts of the world there is no established address system and locations are more or less oriented to significant landmarks. It is difficult for Americans to understand, but in other cultures generations of families grow up in the same neighborhoods. Everyone knows everyone else. Location is personal. In the case of disasters this poses a huge challenge, especially when roads and landmarks are destroyed, and people have evacuated.

The company What3Words (W3W) is tackling this issue. W3W works uses a pixelated Earth system of 3 meter by 3 meter squares. Each grid can be defined by a set of three words. As I write this I am sitting in bump.cans.dome.

W3W does away with traditional numerical latitude and longitude. It works in any language, in fact, eight countries have partnered with W3W as either the nation’s official addressing system or an alternate system, and the United Nations has it among their disaster reporting tools. Art Kalinski, the former writer of this column wrote an article last year about W3W, what3words: The geospatial advancement of the year?

In Puerto Rico, since there aren’t addresses except in urban areas, the remainder of the island had to be geospatially configured to communicate “where” something was located. Digitizing Puerto Rico is a huge geospatial effort that would take years through normal government protocols and cost millions of dollars.

Instead, by enlisting the support of the crowd, it was accomplished in weeks, proving the power if crowdsourcing operations.

Crowdsourcing to the rescue. The power of the crowd was unlocked even more by using geoforms for filling out damage reports like bridge assessments, damaged roads, debris removal, etc. This allowed navigation apps to route around impassable areas saving time and ultimately lives. No more sending a rescue vehicle out only to find it can’t access the area because a tree is down, a bridge is collapsed, or flood waters are too high. Those delivering food could do so to where the people were.

Interactive, real-time, geospatial, command and control forever changed dispatching. Instead of waiting for teams to return before retasking them with new assignments dispatching could be of done on the fly as survivors were identified. The nearest rescue craft with available space could be routed to the exact location.

GIS allowed dispatchers to see where all the rescue teams were and how many survivors they had onboard and how many more they could take on. Data about each survivor was recorded allowing preparations for the arrival of anyone with special needs and the person’s information could immediately show up on a notification board that they had been found and rescued, important for family and friends to know.

The information also helps with forecasting needs of shelters and the reporting of numbers to those in operational authority.

Daily coordination calls were conducted over a variety of platforms with all interested and active participants. Important information was posted on a shared cloud drive. Slack, the peer to peer online collaboration platform was used so FEMA and the various groups were able to collaborate and keep the three different hurricane rescue operations segregated.

Recovery continues. The recovery efforts continue in Houston, Florida, Puerto Rico and the Virgin Islands. In efforts to increase the attention GIS played in mitigating damage from these disasters and the value of crowdsourced information FEMA hosted several events. The final event was held on Saturday, October 21, 2017. It was information about the situation on the ground in the multiple locations and the ongoing operations. It was also a celebration of the successes achieved during these crises; and, a tinge of sadness marked the event bringing to a close to some great working relationships.

If you are interested, there are still ways to get involved no matter what your skillset or expertise. If you have a desire to help, there are opportunities either on scene in the theater of operation, or remotely working from your computer at home. Check with the organizations mentioned below. Even a couple hours of your time can help.

What GIS offers next. GIS in the future of disaster response will make greater use of emerging technologies. Drones will fly preprogrammed paths ahead of a disaster if given enough time, and the imagery and the drone’s flight path will be stored. Then, immediately after the event passes drones will fly the same programmed path capturing imagery with the exact oblique and nadir angles as the original dataset.

Change detection analysis can then be used to find the exact locations of change. This method will become increasingly valuable using high resolution 3D imagery point clouds and used in a change detection system.

Geospatial artificial intelligence systems will identify the areas of greatest damage and assist by directing other resources such as mobile data signals to direct rescue operations towards possible survivors even using the last reported mobile data signal. It can direct human analysts to those specific areas that are inconclusive or require manual verification. This will increase analysis from several weeks to several days.

That is in the future, the near future, perhaps next year’s hurricane season, or tornado season, or snowstorms this winter.

This year, in total, there were 10 Atlantic hurricanes resulting in 431 deaths and an estimated $3.17 billion in damage; which by comparison, is 1/10th the number of casualties from Hurricane Katrina yet nearly twice the level of damage. It just so happens, I went through Hurricane Katrina living along the coast in Bay Saint Louis, Missouri, at the time where the eye the storm passed over. I tried to evacuate but being caught in a 13 hour traffic jam I was unable to outrun the storm. I personally experienced a category 4 hurricane. You may have picked that up in the opening of this article. Those experiences were very real. You might have also picked up my meteorological background from my days in the U.S Navy as a weather analyst.

By the end of 2017, more than hurricanes had inflicted damage. Wildfires in the western U.S. killed another 36 people and destroyed 6,000 buildings. Now, with winter upon us, there will be snowstorms, and GIS will help with those recovery efforts as well.

We are lucky to live in this day and age. Whether you are on the helping end of a disaster aiding in rescue and recovery, or on the receiving end being aided, GIS is supercharging the rescue efforts.

Disaster response agencies and support groups
- Crisis Mappers: Receive recognition badges.
- CrowdRescue HQ
- DigitalGlobe Open Data Program
- DisasterReady.org
- Esri Disaster Relief Program
- FEMA Hurricane Workforce
- URISA GISCorps: GIS Corps volunteers receive free Esri licenses.
- Google Crisis Response
- Humanity Road
- Map Action
- Open Street Map
- Red Cross
- Team Rubicon
- TomNod
- USGS National Map Corps
Most of the above groups support all types of disaster response efforts and many do so throughout all regions of the world.
January 10, 2018
DigitalGlobe releases satellite imagery of Houston

DigitalGlobe released satellite imagery of Houston after Hurricane Harvey hit.

Hurricane Harvey slammed into the Gulf Coast of Texas — just southwest of Houston — on Aug. 25. According to DigitalGlobe, the hurricane packed sustained winds at more than 130 miles per hour and has been identified as the largest single rainmaking event in continental U.S. history.

The images show downtown Houston, George Bush Intercontinental Airport and the interstate highways, which are relatively dry. Significant flooding remains in towns east and north of Houston, including Kingwood, Highlands and Channelview, the company says.

Images courtesy of © 2017 DigitalGlobe

Images courtesy of © 2017 DigitalGlobe

Images courtesy of © 2017 DigitalGlobe

Images courtesy of © 2017 DigitalGlobe

Images courtesy of © 2017 DigitalGlobe

September 5, 2017
Drone survey of seagrasses tested for Texas Parks & Wildlife

Aerial images from a drone are being evaluated as a method to survey seagrasses scarred by boat propellers.

The Texas Parks & Wildlife Department (TPWD) has partnered with Texas A&M University-Corpus Christi to determine if using unmanned aircraft systems is as effective as using planes.

Seagrasses serve as a refuge and nursery ground for fish, shrimp and crabs. They provide oxygen to the water column and serve as an area for growth of drift algae, a food source for shrimp, fish and crabs.

A law prohibiting the uprooting of seagrasses coast-wide was passed by the Texas Legislature during the 83rd legislative session and has been in effect since September 2013. Motorboats cause propeller scarring when they drift into shallow waters and tear a trough in the bay bottom.

Michael Starek, assistant professor of engineering, has been analyzing the images and data collected from flights in December of a small UAS about 450 feet above Redfish Bay’s seagrasses.

TPWD has conducted aerial surveys since 2007 using piloted aircraft flying at an altitude of about 2,000 feet, said Faye Grubbs, Upper Laguna Madre ecosystem leader with TPWD.

The project will compare the output from each method, and analyze costs of processing and ease of mobilization.

TPWD continues to collect aerial imagery in four areas along the Texas coast to evaluate the effects of the regulation. Based on the outcome of this project, Grubbs said the department may use drones for not only monitoring changes in propeller scarring, but possibly for mapping other habitats as well.

“We are comparing the accuracies of the different imagery sets — manned versus unmanned — and how well we are able to map scar features observed in the imagery,” she said.

UAS-collected imagery has the potential to change environmental monitoring at many scales, not just in coastal regions, Starek said.

The first step is to show drone-captured data is comparable to that collected from manned planes. University researchers have been doing just that for several years, flying along the coast and comparing drone-captured images to data from on-the-ground and in-the-water surveying by traditional means.

One of the biggest challenges with aerial imaging of the sea floor is weather and water clarity, Starek said.

“This experiment showed that with proper flight planning for weather conditions, mapping of prop scars with a small UAS can be a viable alternative to more costly, piloted airborne surveys,” Starek said. “Results from the flights show impressive spatial fidelity in the UAS-collected imagery. Pixel resolutions down to one inch will allow mapping of seagrass impacted by prop scaring at very fine spatial detail previously unattainable.”

Although the results show the capabilities, Starek said UAS technology still has to evolve both in platform endurance and in regulations to allow these systems to fly autonomously over much larger areas, such as an entire bay system. This latter component will evolve as the technology and confidence in its use matures.

“In the not too distant future, I can foresee the day when a fleet of small UAS equipped with cameras can routinely map an entire bay system at a fraction of the cost for traditional piloted airborne surveys,” he said. “The potential for UAS technology is immense.”

April 25, 2016