Creating Bathymetry Maps With Coarse Data - Bayesian Kriging Using Open Source Tools Hal Koike University of Hawaii, Hawaii Fisheries Cooperative Research Unit

Why do we need a Bathymetry Map?

Marine resource management is pushed toward ecosystem based management (e.g. linking with land development, marine protected area)

You need spatial data to fully understand the ecosystem of your interest

Species distribution for marine organisms is known to be influenced by depth

Outside the United States…

Most countries do not have a spatial data repository where bathymetry data, land cover data, etc. is readily available to be used for analysis.

If $$ is Limited, What are the Options?

Stick with what you have

Create a pseudo-bathymetry map Some budget friendly data covering the world

(bathymetry case)

Navigational chart (low cost)

MODIS (free)

Hyperion (free)

Case for Seychelles…

What is available

What I need

Solution

Create a pseudo bathymetry map using Bayesian Kriging option in GeoR (Rilbeiro jr., P.J. and Diggle, P.J. 2001)

What is GeoR?

Created by Paulo J. Ribeiro Jr. and Peter J. Diggle.

One of the many packages available through R-CRAN project

Operated on R

Step 1. Georectification

Step 2. Enter the Depth Data

What it looks like after entering all the points

Step 3. Import the Point Data to Geo R

Step 4. Find your Range

Step 5. Run the Bayesian Kriging Simulation

x <- seq(241472,403019,2000)

y <- seq(9449003,9559751,2000)

d1 <- expand.grid(x=x,y=y)

ex.bayes <- krige.bayes(YourData,loc=d1,model=model.control(cov.m="matern",kappa=0.5),prior=prior.control(phi.discrete=seq(0,80000,l=10),phi.prior="reciprocal"))

Predicted Values

Predicted Values

Error of Predicted Values (Estimation Variance)

Error of Predicted Values (Estimation Variance)

Accuracy Check

Accuracy Comparison

Bathymetry Map Standard Deviation

SRTM 30 (1km grid) 76.89

Bayesian Kriging (2km grid) 9.00

Conventional Kriging (2km grid) 8.30

Statistically simulated bathymetry map had less deviation then remotely sensed data