Evaporation from a riparian system in a semi-arid environment

Abstract

Abstract:Measurements of micrometeorological variables were made for a complete annual cycle using an automatic weather station and two energy budget±Bowen ratio systems at a ®eld site adjacent to the Santa Cruz River in southern Arizona. These data were used to provide the basis of an estimate of the evaporation from a one-mile long losing reach of a riparian corridor in this semi-arid environment. A remotely sensed map of vegetation cover was used to stratify the corridor into ®ve categories of surface cover. The total evaporation was calculated as the area-weighted average of the measured evaporation for sampled areas of the two most common covers, and appropriate estimates of evaporation for the less common covers. Measurements showed a substantial, seasonally dependent evaporation from the taller, deep-rooted riparian cover in the study reach, while the short, sparse vegetation provided little evaporation. In terms of the volume of water evaporated from the study reach, the evaporation from irrigated agriculture accounts for almost half of the total loss, while the majority of the remaining evaporation is from the taller riparian vegetation covers, with about one-quarter of the total loss estimated as coming from obligatory phreatophytes, primarily cottonwood. #

Análise da evapotranspiração por wavelet de Morlet em área de Vochysia divergens Pohl no Pantanal

“…Os fluxos de calor latente (LE) e sensível (H) foram estimados a partir do balanço de energia à superfície terrestre de acordo com a equação de Bowen e conforme recomendação de Perez et al (1999) e Unland et al (1998). Maiores detalhes sobre a metodologia adotada para determinação dos fluxos de energia estão apresentados em Sanches et al (2011).…”

Nitrogen effect on carbon-water coupling in forests, grasslands, and shrublands in the arid western United States

“…In particular, deep‐rooted phreatophytes can account for significant water uptake for plant use and transpiration in shrub ecosystems. Unland et al [1998] found that evapotranspiration in the Santa Cruz River in southern Arizona is dominated by riparian phreatophytes, accounting for as much as half of the total nonirrigated evapotranspiration (ET). Domingo et al [1999], testing a model in SE Spain, also found that accounting for the total soil water content, including deep water, was crucial to calculating the correct ET.…”

Comparison of methods to estimate ephemeral channel recharge, Walnut Gulch, San Pedro River Basin, Arizona

“…The resulting transpiration rates were significantly lower than anticipated and where closer to bare soil or winter rates. Estimates an adjacent mesquite site on the San Pedro River (~4.3 mm/day) and the Santa Cruz riparian area (~4.1 mm/day) Unland et al, 1998]. It was judged that the sapflux derived values of mesquite transpiration were far too low to be realistic and were there-10 COMPARISON OF METHODS TO ESTIMATE EPHEMERAL CHANNEL RECHARGE fore not used in the water balance summarized in Table 1.…”