Spatial and temporal trend in monthly and annual reference evapotranspiration in Madagascar for the 1980-2010 period

Abstract

The temporal trend and spatial distribution of reference evapotranspiration was investigated across Madagascar for the period of Air temperature relative humidity temperature relative humidity solar radiation and wind speed were collected from weather stations across the country and were used to estimate daily reference evapotranspiration ET by the Penman Monteith equation Monthly average daily ET and the total annual ET were estimated The Mann Kendall test was used for the temporal trend analysis in monthly average daily ET and the total annual ET and the Sen rsquo s method was used to estimate the rate of change in ET during the study period The spline interpolation method was used for spatial interpolation of the variation in annual and monthly average ET The results showed southwest north East trend in ET Reference evapotranspiration was higher at the western semiarid region than the humid eastern region ET peaked during the period of September October Annual total ET varied from mm in Andapa at northeast to mm in Antsohihy at northwestern coastal region Overall there was an increasing trend in annual total ET however the upward trend was significant only at out of weather station sites while monthly ET did not show consistent trends This is one of the first comprehensive studies that investigate spatial and temporal dynamics of ET in Madagascar which can aid in developing appropriate adaptation strategies to improve crop water use and evaporative losses estimates for maintaining or increasing food production while enhancing water use efficiency in the western semiarid regions of Madagascar