The Potential Role of Water Quality Modeling in Coastal Acidification Management

The Potential Role of Water Quality Modeling in Coastal Acidification Management

Damian C. Brady, Ph.D.

Ira C. Darling Marine Center

University of Maine

August 1st, 2014

The Potential Role of Water Quality Modeling in Coastal Acidification Management

Damian C. Brady, Ph.D.

Ira C. Darling Marine Center

University of Maine

August 1st, 2014

…or whatchya gonna do about it?

First of all…

• After we determine if acidification is a problem• Now what?...what do we do societally to ‘fix’ the problem

• I know of no model of pH/aragonite saturation/alkalinity/DIC that is currently used to make management decisions

But…there are interesting analogs to consider• We know that degradation of organic matter (and all

respiration) can contribute to lowered dissolved oxygen and pH…increased CO2

• We know that freshwater flow can bring in acidified water (Salisbury et al 2011)

• We know that eutrophication and reduce the buffering capacity of estuaries (Cai et al 2011)

• The relevant knob to turn becomes land derived nutrient and ‘pH’ loading…we’ve essentially been doing this for decades

NOAA

MODELS

• All models are wrong, some models are useful• Models come ins all sort of flavors and colors

• But broadly speaking many of the management models we talk about are either empirical/deterministic or process based

• There are advantages and disadvantages of both

Eutrophication and Hypoxia as Convenient ‘Models’

Empirical Model

• Develop a relationship between loading and hypoxic area (or “acidic” area

• Then show this relationship to farmers and kindly ask them to reduce May nitrate+nitrite loading

This is where your ecology/fisheries/resource

management is added

Empirical Models

• They assume your time series contains all possible scenarios

• Without process level understanding, you don’t know why your relationships work…some argue that without this understanding, predictions are doomed to fail…

Chesapeake Bay Program Decision Support System: “The Cadillac”?

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Management Actions

Watershed Model

Bay Model

CriteriaAssessmentProcedures

Effects

Allocations

Airshed Model

Land UseChange Model

ScenarioBuilder

Sparrow

Process Level Models are Complex and Data Intensive Our challenge will be to fold in the calculation of

aragonite saturation, DIC, pH, alkalinity into thes models

Then determine the size, severity, and duration of non-livable zones

But they give you more power to explore hypotheticals

Scales: Airshed to Watershed to Water Column to Sediments

Watershed Models

What do we have in Maine?

• An amazing hydrodynamic modeling infrastructure• http://www.norwich.edu/about/news/2008/050208-

cascoBayDyeMovie.html• An large monitoring network from DMR’s Division of Public

Health, Citizen Monitoring Groups, NGO’s, Universities, DEP, etc

• WHAT WE DO NOT HAVE?• Biogeochemical modeling• Watershed modeling• Ecosystem based approaches to dealing with abiotic

management issues

Existing Cobscook Bay Model

20 m in the outer Cobscook Bay

Existing Saco-Casco Bay Model

> 8 m in Saco> 20 m in Casco

Working on Downeast Model

100 m nearshore