Deforestation Effects on Sedimentation of Watersheds and Marine Environments:

MaMaBay, Madagascar

Shreya Basu, Dani Ewert, Rachael Maingot, Jing Wang

Methodology

Determine the existence and extent of

deforestation from 1990 to 2010.

Evaluate the extent and quantity of erosion and

sedimentation in watersheds from 2000 to 2010.

Illustrate that the rate of change of sedimentation

entering the bay ecosystem related to

deforestation and erosion from 2000 to 2010.

Study Area

MaMaBay is comprised of two parks (Makira and

Masoala protected in 2009 and 1997, respectively)

and Antongil Bay. The concern for this area is the

effect of deforestation for agricultural purposes and

illegal logging may lead to biodiversity loss and land

degradation. This area maintains 1% of the earth’s

biodiversity. This ecosystem is the home of several

plant and animal species (including humans), and is

in need of further protection to ensure the health of

the land and water ecosystems are maintained.

Data Area C: This watershed area has seen most of its deforestation

occur between 2000 to 2010, with the maximum deforestation of

12-15% per watershed. This area of deforestation occurs mostly

outside the protected MaMaBay boundary, but is contributed to the

second largest plume in the bay within the MaMaBay boundary.

Area D: Maximum deforestation of about 12-15% per watershed

has occurred within the protected areas of the peninsula between

1990 to 2010. The shallows bordering this land mass is home to

shallow, fertile reef systems.

Further Research: Examine villages and roads as driver variables

to deforestation. Collect soil samples and cropping samples to

validate current research.

Main Findings

Revised Universal Soil Loss Equation= R*K*L*S*C*P,

where R is the rainfall and erosivity index, K is the soil

erodibility factor, L is the slope length factor, S is the slope

steepness factor, C is the cropping factor, and P is the

conservation practice factor.

This equation estimates the average potential soil loss

within the MaMaBay boundary. The average soil loss

between 2000 to 2010 is 0 to 500 tons per hectare

per year. Potential soil loss is at greatest risk in the

forest north of Antongil Bay and northeastern region

of the Masoala National Park, at a potential rate of 61

to 140 tons per hectare per year.

Erosion Risk Map

Deforestation, Potential Soil Loss, and Sedimentation In region ① , the rate of deforestation per watershed varies between 6 to 15% of the entire watershed,

and is increasing non-forest coverage from 1990 to 2010. As seen in the potential soil loss image,

region ① also is at risk of 36 to 140 tons per hectare per year of soil loss. The largest sedimentation

plume in Antongil Bay was found in the estuary of region ① , and has a strong correlation of

continuously increasing throughout 2000 to 2010. There are also high rates of deforestation occurring

in region ② with 6 to 15% deforestation occurring per watershed, and this change has occurred mostly

between 2000 to 2010. The second largest sedimentation plume in the bay is found here, with a

comparable magnitude of continuously increasing similar to the northern plume. Throughout the entire

Antongil Bay, there is an continuously increasing trend of sedimentation through 2000 to 2010.

Deforestation Deforestation

1. Used 3 Landsat-7 images to classify

landscape into Forest, Non-forest and Water

for 2010.

2. Reclassified CI map to show land change in

1990, 2000, and 2005.

3. Corrected missing values in 2010 with

previous CI maps.

Soil Erosion

1. Generated 6 factors with rainfall, soil,

elevation, and vegetation data.

2. Estimated of soil loss throughout MaMaBay

boundary from 2000 to 2010.

3. Derived watershed map using DEM.

Sedimentation

1. Used MODIS Level 3- 16 day product

aggregated into a monthly product showing

ocean color anomalies.

2. Conducted a times series analysis used to

show overall variance in ocean color

anomalies from 2000 to 2010.

Research Objectives

1990 to 2000: Deforestation occurred mainly along the

northern border of the MaMaBay boundary, and between

the villages bordering the north section of the bay and

forest just north of the villages.

2000 to 2005: The total amount of deforestation

exceeded the amount in the previous ten years with

annual deforest rate tripled from 1,246 ha/yr to 3,628

ha/yr. New areas of deforestation are located along the

northern and southern boundary of Masoala, the core

forest between the villages and northern MaMaBay

boundary, and along the east coast of bay.

2005 to 2010: Deforestation continues to increase

effecting core and edge forest within the entire study

area.

①

②

12,461

18,138

21,125

1,246

3,628

4,225

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

0

5,000

10,000

15,000

20,000

25,000

1990-2000 2000-2005 2005-2010

Deforestation (1990-2010): Hectares

Total Deforestation

Deforestation per year

Data Source

Range

Units Resolution/MMU

Range

(values) (time)

Landsat ETM+ NASA

0-1

Meter 30 m

Date: 09/06/2010

Path: 158 Row:71

Date: 09/06/2010

Path: 158 Row:70

Date: 04/11/2011

Path: 158 Row:70

Bands

1-5,7

Conservation International

Maps

Conservation

International N/A Meter 30m 1990, 2000,2005

Shapefiles from WCS

Wildlife Conservation

Society Various Various Various Various

SRTM DEM SRTM data warehouse 0 - 2000 Meters 90m 2000

FAO Soil Data

FAO Institute,

GeoNetwork N/A N/A N/A 1978, updated 2003

Antalaha Rainfall Data

National Climatic Data

Center CSB N/A mm/hr N/A 1997-2010

MODIS CMG Monthly

NDVI NASA, Clark Labs 0 - 1 Degrees 0.5°x0.5° 2000 - 2010

MODIS, MCD43A4 NASA Bands 1, 3-4 Meters 500m 02/14/2000-12/27/2010

Area A: This watershed area lies mostly within the protected

MaMaBay boundary. Maximum deforestation of 12-15% per

watershed has occurred within the protected areas between 1990

to 2010. Average potential soil erosion of 61 to 140 ton per

hectare per year may occur in this area within the boundary. The

largest plume discovered in the bay receives sediment from this

entire area. This plume has been continuously increasing in

sedimentation with only a 1% probability this happened by

chance.

Area B: This watershed area is split between being inside and

outside the MaMaBay boundary. Maximum deforestation of about

12-15% per watershed has occurred within the protected areas

between 1990 to 2010. Average potential soil erosion of up to 61

to 140 ton per hectare per year may occur in this area within the

boundary. The shallows bordering this land mass is home to

shallow, fertile reef systems.