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1 1.10 Application of estuarine and coastal classifications in marine ...

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<strong>of</strong> loss are through urbanization, conversion to agriculture <strong>and</strong> mariculture, human modifications<br />

to <strong>coastal</strong> hydrology, pollution, l<strong>and</strong>fill, salt production <strong>and</strong> direct use <strong>of</strong> trees for timber, fuel<br />

<strong>and</strong> medic<strong>in</strong>es (Valiela et al. 2001, Walters et al. 2008). Mangroves have also been destroyed<br />

<strong>and</strong> degraded by hurricanes <strong>and</strong> tsunamis (Alongi 2008, Giri et al. 2008) <strong>and</strong> now sea-level rise<br />

has been identified as a substantial cause <strong>of</strong> recent <strong>and</strong> predicted future reductions <strong>in</strong> the area <strong>and</strong><br />

health <strong>of</strong> mangroves (Gilman et al. 2008).<br />

Classified remote sens<strong>in</strong>g imagery such as generated from spectral <strong>in</strong>terpretation <strong>of</strong><br />

L<strong>and</strong>sat TM data provides a time series appropriate for a quantitative synoptic change detection<br />

to assess the distribution <strong>of</strong> mangroves <strong>and</strong> to document quantitatively how the spatial pattern<strong>in</strong>g<br />

<strong>of</strong> mangroves (losses, ga<strong>in</strong>s, contiguity/fragmentation) have changed. Comb<strong>in</strong><strong>in</strong>g map products<br />

with spatial analyses <strong>and</strong> data from <strong>in</strong>vestigation <strong>of</strong> the causal mechanisms that have led to<br />

changes <strong>and</strong> characterization <strong>of</strong> areas that have experienced most change will provide valuable<br />

<strong>in</strong>formation to support resource management decision-mak<strong>in</strong>g, policy formulation <strong>and</strong> public<br />

education. Giri et al. (2008) <strong>in</strong>terpreted a L<strong>and</strong>sat time series to estimate the extent <strong>of</strong> tsunamiaffected<br />

mangrove forests <strong>in</strong> SE Asia <strong>and</strong> to determ<strong>in</strong>e the rates <strong>and</strong> causes <strong>of</strong> deforestation from<br />

1975 to 2005. Us<strong>in</strong>g a post classification change detection approach for <strong>coastal</strong> areas <strong>of</strong><br />

Indonesia, Malaysia, Thail<strong>and</strong>, Burma (Myanmar), Bangladesh, India <strong>and</strong> Sri Lanka, the<br />

analyses determ<strong>in</strong>ed that the region had lost 12% <strong>of</strong> its mangrove forests from 1975 to 2005<br />

(Figure 19). Rates <strong>and</strong> causes <strong>of</strong> deforestation varied both spatially <strong>and</strong> temporally. Annual<br />

deforestation was highest <strong>in</strong> Burma (c. 1%) <strong>and</strong> lowest <strong>in</strong> Sri Lanka (0.1%). In contrast,<br />

mangrove forests <strong>in</strong> India <strong>and</strong> Bangladesh rema<strong>in</strong>ed unchanged or ga<strong>in</strong>ed a small percentage.<br />

Change detection revealed that the major causes <strong>of</strong> deforestation were agricultural expansion<br />

(81%), aquaculture (12%) <strong>and</strong> urban development (2%) (Figure 19). This type <strong>of</strong> application can<br />

48

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