Watershed analysis in Guatemala

Including collected and generated data for

Guatemala as well as some basic regional

statistics calculated for the 40 major watersheds.

Maps prepared by the

Spatial Information and Analysis Group, DECRG, World Bank

September 2001Data sources, too numerous to mention…..sorry!

Municipios

Colours represent departments, municipal boundaries shaded in gray.

40 Major Watersheds

Rio PazWatershed

LandSat ETM images

Rio PazWatershed

Elevation

Terrain Typology

Plains - Greens

Lowlands - Yellows

Hills - Red

Mountains - Grey

High Mountains - White

Land Cover

Forests - Green

Agriculture - Light Yellow

Water - Blue

Other - Pink

Urban - Red

Population Density

Poverty Rate (General)

Low - Green

Medium - Yellow

High - Orange

Critical - Red

Poverty (General)

Population per municipio classified as being poor

Poverty Rate (Extreme)

Low - Green

Medium - Yellow

High - Orange

Critical - Red

Poverty (Extreme)

Population per municipio classified as being extremely poor

Forest / Agri. on Slopes

Forests - Green

Agriculture - Orange

Defining upper watershed areas

5 example methods

1) Use an elevation cut off across the region

2) Split each watershed into 3 based on elevation

3) Derive 3 terrain types (Meybeck) across the region

4) Use a flow length cut off across the region

5) Split each watershed into 3 based on flow length

1) Elevation - Region

Low - Green

Mid - Yellow

High - Grey

2) Elevation - By shed

Low - Green

Mid - Yellow

High - Grey

3) Terrain - Region

Low - Green

Mid - Yellow

High - Grey

4) Flowlength - Region

Low - Green

Mid - Yellow

High - Grey

5) Flowlength - By shed

Low - Green

Mid - Yellow

High - Grey

Comparing the 5 examplesHow much land is in each region?

% area in each region

0%

10%

20%

30%

40%

50%

60%

70%

Low Mid High

Elev-Region

Elev-Shed

Terrain-Region

Flow-Region

Flow-Shed

Comparing the 5 examplesHow many people are in each region?

Population in each region

-

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

Low Mid High

Elev-Region

Elev-Shed

Terrain-Region

Flow-Region

Flow-Shed

Comparing the 5 examplesHow many poor are in each region?

Poor (General) in each region

-

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

4,500,000

Low Mid High

Elev-Region

Elev-Shed

Terrain-Region

Flow-Region

Flow-Shed

Comparing the 5 examplesHow much forest is in each region?

km2 of forest per region

-

5,000

10,000

15,000

20,000

25,000

30,000

Low Mid High

Elev-Region

Elev-Shed

Terrain-Region

Flow-Region

Flow-Shed

Defining upper watershed areas

There is a lot of variation across the 5 methods

methods 2 and 5 (that split each watershed into 3) consistently give high values in the high region,

methods 1 and 4 consistently give low values in the high regions

method 3 consistently gives values that lie in between

Taking method 3 as an example….

Class Area (km2) Agriculture (km2) Forest (km2) Low 62,175 (57%) 30,668 (58%) 27,438 (57%)Mid 16,958 (16%) 9,416 (18%) 5,830 (12%)High 29,297 (27%) 12,698 (24%) 15,128 (31%)Total 108,429 52,781 48,395

Defining High / Mid / Low landsUsing Method 3: Terrain Typologies (Meybeck et al. 2001)

Class Population (2000) Poverty (General) Poverty (Extreme)Low 2,498,093 (22%) 1,552,135 (25%) 542,990 (21%) Mid 3,197,987 (28%) 1,187,251 (19%) 430,058 (17%) High 5,694,926 (50%) 3,494,186 (56%) 1,621,909 (63%)Tot 11,391,006 6,233,572 2,594,956

Population estimated for year 2000 per municipality, (MAGA / BID)

Poverty rates per municipality from official Guatemala poverty map (SEGEPLAN / World Bank)

Selecting watersheds to analyse

We could remove a certain number of watersheds by imposing criteria such as

We are only interested in watersheds that have > 20% of there area classified as ‘high’. Taking method 3 as an example, this would remove all low lying watersheds

Selected Watersheds

Selected watersheds shaded in yellow