Miguel Santistevan
CE 547 – Assignment #2
February 5, 2008
New Mexico Pan Evaporation Study
The following map illustrates the location of pan evaporation study sites in New Mexico. Six sites in six counties were chosen to analyze the amount of pan evaporation in two North to South transects in the central and eastern parts of the state.
The study sites along the N-S transects used in this study are listed in the table below:
|
Transect 1 |
Transect 2 |
||||
|
Color code |
County |
Site |
Color code |
County |
Site |
|
Light blue |
Rio Arriba |
El Vado Dam |
Light green |
Union |
Capulin Nat’l Mon |
|
Yellow |
Valencia |
Los Lunas |
Dark blue |
De Baca |
Alamagordo Dam |
|
Red |
Doña Ana |
Jornada Exp Range |
Pink |
Eddy |
Lake Avalon |
The following graph and shows the pan evaporation data for the sites detailed above.
Note that there is an increase in pan evaporation from North to South for both transects. Transect 1 (central NM) shows a evaporation of 75 inches per year in the north, to 81 inches/yr in the central part of the state, and 91 inches/yr in the south. Transect 2 (eastern NM) similarly shows 97 inches/yr in the north, to 109 inches/yr in the central region, and 117 inches/yr in the south. The following table describes these relationships:
|
|
Transect 1 |
Transect 2 |
|
North |
75 |
97 |
|
Central |
81 |
109 |
|
South |
91 |
117 |
It is interesting to note that the relationship holds from north to south for both transects, while the north site of Transect 2 shows more evaporation than the southern site of transect 1, negating the influence of latitude alone. The decrease of evaporation along the transects from south to north is likely due to a decrease of solar radiation striking the Earth along the same axis. The increased evaporation along the eastern N-S transect is likely due to either the effects of lower elevations, the influence of wind and temperature of the open plains (compared to the mountainous Rio Grande corridor), and/or lower humidity that is presumed to occur on the eastern plains than over the Rio Grande basin. Further data would need to be incorporated into this analysis to confirm causes of this result.