# Presentation: 873285

## Please note: this presentation has not received Director’s approval and is subject to revision.

## High-Resolution Bathymetric Mapping of the Estero Bay and Caloosahatchee Estuaries

**High-Resolution Bathymetric Mapping of the Estero Bay and Caloosahatchee Estuaries**

- Mark Hansen and Gina Peery – USGS
- Wayne Wright - NASA

## What are MFLs?
Flow or level of ground or surface water at which further withdrawals of water would be significantly harmful to the water resources or ecology of the area. 

Why are MFLs being established? 
To maintain environmental quality.
To protect water resources and ecology such as fish production and wetlands. 
To determine water availability.

How does bathymetry of the estuary play a part in establishing MFLs?
MFLs requires the development of hydrodynamic models.
Models require the quantification of present day bathymetry.
Present data is > 50 years old, and changes over time.
FL Statute directs the District to the use best information available.

- Flow or level of ground or surface water at which further withdrawals of water would be significantly harmful to the water resources or ecology of the area.
- Why are MFLs being established?
- To maintain environmental quality.
- To protect water resources and ecology such as fish production and wetlands.
- To determine water availability.
- How does bathymetry of the estuary play a part in establishing MFLs?
- MFLs requires the development of hydrodynamic models.
- Models require the quantification of present day bathymetry.
- Present data is > 50 years old, and changes over time.
- FL Statute directs the District to the use best information available.

**WHY COLLECT NEW BATHYMETRY?**
-  Support Minimum Flow Levels (MFL) studies

## Survey Area

- Charlotte Harbor
- Matalatcha Pass
- Caloosahatchee River
- Estero Bay
- Offshore

## USGS Boat and NASA Airborne Systems

- Utilizes the best of both systems

- NASA lidar aircraft

- USGS survey boat - offshore

-       SANDS (sonar)				EAARL (lidar)

## DISADVANTAGES     ADVANTAGES

- R & D funded
- Precision GPS based
- +/- 8cm random error
- Shallow to deep water (>0.3m)
- Narrow footprint
- Unaffected by clarity
- Single beam sonar
- Limited by waves

-  **SANDS****	****	****	****  EAARL**

- R & D funded
- Precision GPS based
- +/- 15cm random error
- Shallow water (>0.5m)
- Swath coverage
- Topo and bathy data
- Fast
- Depth limited (< 2.5 sechi disk)
- Clarity limited
- Limited airspace

## Reference Station Position DeterminationSANDS and EAARL

- GPS Processing Tools

- Control Spreadsheet

- SCOUT (Scripps)

- OPUS (NOAA)

- GIPSY (JPL)

## Survey Pattern 

**Survey Pattern**

- SANDS					EAARL

## USGS  Shallow And Nearshore Depth System (SANDS)

- GPS Reference Station

- Ship GPS

- GPS NAVSTAR Constellation

- Pitch/Roll Sensor

- Fathometer

- Nav/Logging Computer

**USGS  Shallow And Nearshore Depth System (SANDS)**

## GPS Differential Reference Station

-  Boat roves <15 km from reference station
-  Several sites per project

**<15 km**

## Quality Assurance/Quality Control 

-  Adhere to known GPS limitiations
- Roving distance, atmospheric conditions, #sv’s
-  Strict control on GPS data processing

- Trackline crossing differences		   TINs show anomalies

- GIS Editing

## EAARL:  airborne contributions (spatial)

**NASA Experimental Advanced Airborne **
**Research Lidar (EAARL)**

-  Precision navigation
-    and position

-  Digital photographic
-    camera

- Precision attitude
-   and heading

## EAARL:  lidar (basic characteristics)

**EAARL Lidar**

**Green laser             ****(532 nm)**
**   ** **High pulse rate   ****(3000 Hz)**
**    ****Low power          ****(70 ********J/pulse)**
** **

**Raster scanning    ****(25 rasters/sec)**

**Small footprint       ****(15 cm)**

**1 x 1 m sample spacing**

**Shallow depth range  ****(0.5 – 15 m)**

**Notes:**
green (532 nm)
240-m swath, 120 spots/swath, 43-80 km2/hr
25 rasters/sec
waveform-resolving (1 nsec)
coupled digital aerial photography
precision navigation

## EAARL:  lidar (waveform-resolving)

**43 km****2****/h**
**25 rasters/sec**
**waveform-resolving (****1 nsec)**

**EAARL Lidar**

**Waveform-resolving:**

**Temporal resolution = 1 nsec**
**Relsolve 1.5 cm in water**

***t  ***

***t  ***

***I  ***

***I  ***

**Notes:**
green (532 nm)
200-m swath
25 rasters/sec
waveform-resolving (1 nsec)
coupled digital aerial photography
precision navigation

## EAARL Data

- Lidar data before false turbidity returns have been filtered out.

- Lidar data after false turbidity returns have been filtered out.

**EAARL Data**

## EAARL/SANDS 

**EAARL/SANDS **
**Intercomparision Area**

## Intercomparision between the SANDS and EAARL Measurements

- 2309 comparisions.
- EAARL data is with 3m of SANDS
-    data points.
- Overestimation between -27 and
-   -27.5m due  to the surface return
-   pulse becoming convolved
-   with the bottom return pulse.
- Will be corrected in the final
-    data set.

**Intercomparision between the SANDS and EAARL Measurements**

## Intercomparision between the SANDS and EAARL Measurements

- 2309 comparisions.
- EAARL data is with 3m of SANDS
-    data points.
- Overestimation between -27 and
-   -27.5m due  to the surface return
-   pulse becoming convolved
-   with the bottom return pulse.
- Will be corrected in the final
-    data set.

**Intercomparision between the SANDS and EAARL Measurements**

## Datum Issues

- Horizontal
- WGS84(ITRF00 -> WGS84(original)
- WGS84(original) ~ GRS80/NAD83
- Vertical
- WGS84(ITRF00 -> WGS84(original)
- WGS84(original) -> NAVD88
- NAVD88 ~ WGS84(original) – Geoid ht
- 	Using the GEOID99 model
- MLW = NAVD88 – (local constant)

- Conversion from GPS data to conventional datums

- NOAA Tidal Benchmark

## Final Products

- Tabular XYZ data
- Contoured data
- Grids
- USGS quadrangle style maps