Status
Status
of Guatemala and Honduras. In the northern MAR
watersheds (Quintana Roo and Belize), discharge
NOAA's Nonpoint Source Pollution and Erosion
rates remain much closer to hypothesized natural
Comparison Tool (N-SPECT) estimates sediment
conditions. Completely natural land cover conditions
delivery at river mouths draining into marine areas
have not existed in the MAR for the last few millennia,
proximate to the Mesoamerican Reef9. This model was
since before Mayan agricultural civilizations.
used to estimate and compare sediment delivery for
Data Needs
two land cover scenarios: "natural" versus "current"
(i.e., 2003/2004)12.
Measurements of sediment delivery rates at a variety
of river mouths are needed to assess the accuracy of
The model results indicate that, on average, at a
modeled estimates. New model versions could include
regional level, current rates of sediment delivery may
a variety of agricultural management practices, to help
be over 20 times that of natural (no development)
evaluate the sediment-delivery impacts of different
conditions. The model also indicates that sediment
land management approches.
delivery rates deviate most severely from hypothesized
natural conditions in the southern MAR watersheds
Comparison of Regional Results for Annual Model Runs for Current and Natural Land Cover
Sediment (mt)†
Scenario
Freshwater Discharge (m3)
Current (2003/2004)
60,088,829,077
431,129,480
Natural (no development)
34,501,909,421
19,115,006
Ratio of Current / Natural
1.74 (174%)
22.55 (2255%)
Date Source12
Note: Sediment delivery represents an upper-bound estimate for the region, as sediment attenuation due to redeposition en route to
the river mouth is not accounted for. The values reflect overall erosion within the region and are indicative of the overall magnitude of
sediment delivery, but should not be regarded as absolute values. The relative relationship between the scenarios is valid.
D5
†
mt=metric tonnes
95