Catttle impoundment data evaluation

Cattle impoundment data evaluation

In this document we evaluate the procedure used for selecting cattle impoundment areas out of the National Water Agency (ANA) dataset of impoundments, and with support of the Mapbiomas Pasture and Water datasets.

The main steps are:

• The ANA dataset was imported in Google Earth Engine, and a 200m buffer area around the impoundments was drawn. The buffer area was then intersected with the Mapbiomas pasture and water datasets, and the area covered by pasture and water was calculated for each impoundment and buffer areas. The area covered by pasture and water was then used to calculate the percentage of pasture and water in the impoundment and buffer area.
• The ANA dataset and the pasture and water areas in the impoundment and buffer areas were used to select the impoundments that were used for cattle.
• The filtering process was done through the following steps:

1. Only impoundments included in the ANA ‘reservoir evaporation report’ were considered.

2. The impoundments were selected based on their main use, and only impoundments with ‘Unknown’, ‘Abastecimento animal’ (animal water supply), or ‘Dessedentação animal’ (animal drinking) were selected.

3. The impoundments were then filtered by the percentage of water area found in the impoundment area in that year, according to the estimation made in Google Earth Engine. Impoundments with more than 0% of water in the impoundment area were selected.

4. Finally, the impoundments were then filtered by the percentage of pasture in the buffer area. A series of threshold percentages were estimated, and we are yet to define what is the most appropriate percentage.

Area covered by impoundments according to the ANA impoundment dataset, in km^2

## Joining, by = "usoprinc"

Water surface area for different impoundment types in ANA database

uses	total_area_km2	n	mean_area_km2
Unknown	6513.48	169259	0.04
Irrigation	970.84	1547	0.63
Hydroelectric	33970.47	956	35.53
Human water supply	2934.06	792	3.70
Mining reject	182.83	442	0.41
Animal drinking	76.32	235	0.32
Flow regulation	530.98	176	3.02
Aquaculture	50.55	131	0.39
Recreation	9.85	47	0.21
Industrial	20.37	43	0.47
Drought prevention	69.09	29	2.38
Water supply	10.49	16	0.66
Water supply [generic]	3.22	11	0.29
Flood protection	83.28	10	8.33
Fish production	1.91	6	0.32
Irrigation and water supply	0.93	4	0.23
Animal water supply	0.08	1	0.08
Agriculture	0.99	1	0.99
Industrial reject	0.01	1	0.01

Water surface area for different impoundment types in ANA database, for the main uses we selected

uses	total_area_km2	n	mean_area_km2
Unknown	6513.48	169259	0.04
Animal drinking	76.32	235	0.32
Animal water supply	0.08	1	0.08
Agriculture	0.99	1	0.99
Total	6590.87	169496	1.43

Filtering the areas based on water and pasture area from Mapbiomas

Filtering by existence of water in the impoundment area

As stated above, the total area of impoundments in the ANA database selected is around 6590 km2.

Filtering by percentage of pasture area in buffer area

Note: in this graph there are multiple points for the same threshold, as these represent different years.