Spatial and Statistical Variability Analyses of Satellite-Based Climatic Data in Mereb-Gash Basin

Abstract

Global reanalysis products are extensively used for hydrologic applications in sparse data regions. The establishment of some inputs for hydrologic modelling from global reanalysis requires prior scrutiny and assessment. Thus, the present study attempts to exploit Climate Forecast System Reanalysis datasets for the Mereb-Gash river basin in Eritrea, with the objective of preparing input data for future hydrological modelling efforts as well as climate characterization. The research activities include statistical analysis of reanalysis datasets, computation of potential evapotranspiration and drought indices using different approaches. Results show that there were predominantly significant monotonic trends in most of the data; precipitation and relative humidity exhibited significant decreasing trends, whereas increasing trends were detected in temperature and potential evapotranspiration. Three potential evapotranspiration estimation methods were employed out of which the Thornthwaite method showed a considerable dependence on elevation of a station. In most cases, Penman-Monteith provides higher estimates than Hargreaves and Thornthwaite equations. Besides, drought indices based on standardized precipitation evapotranspiration and rainfall anomaly demonstrate the presence of persistent dry conditions over the period 2000 to 2013 and predominantly humid conditions from 1979 through the end of 1990s. The findings of this study imply that presence of significant trends in most of the climatic variables and persistent drought conditions in recent years may ultimately be associated to human and climate influences on the environment. Thus, concerted and effective countermeasures should be executed in the study area to reverse the existing ecological imbalances.