Recent and long term variations in ice extent on Kilimanjaro are investigated in the context of 20th century climate change in East Africa. Quickbird satellite data show that the areal extent of glaciers on Kilimanjaro is 2.51 km2 in February 2003. To assess glacier retreat on Kilimanjaro two glacier systems are identified: (1) plateau (≥5700 m) and (2) slope (<5700 m). Vertical wall retreat that governs the retreat of plateau glaciers is irreversible, and changes in 20th century climate have not altered their continuous demise. Rapid retreat of slope glaciers at the beginning of the 20th century implies a strong departure from steady state conditions during this time. This strong imbalance can only be explained by a sudden shift in climate, which is not observed in the early 20th century. Results suggest glaciers on Kilimanjaro are merely remnants of a past climate rather than sensitive indicators of 20th century climate change.

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ABSTRACT:The purpose of this study is to determine the hydrological impacts of land use/land cover (LULC) change in the Yom watershed in central-northern Thailand over a 15-year period using an integration of remote sensing, Geographic Information System, statistical methods, and hydrological modelling. The LULC changes showed an expansion of urban areas by 132% (from 210 km 2 in 1990 to 488 km 2 in 2006). The Yom River's daily discharge long-term trend significantly increased at most of the measurement stations (p value <0.05), and the rate of increase in discharge at areas downstream of the rapid urbanisation was significantly greater than that at areas upstream. There were no significant long-term trends in precipitation characteristics in the basin, except for one station. The rate of change in discharge after changes in LULC showed a systematic increase over a range from 0.0039 to 0.0180 m 3 s −1 day −1 over a 15-year period, with the increase in urbanised area spanning a range from 81 to 149% in two flood-prone provinces. A rainfall-runoff model simulated a small increase (∼10%) in peak flows. The coupling of surface observations, remote sensing, and rainfall-runoff modeling demonstrated the impacts of changes in LULC on peak river discharge, hence flooding behaviour, of a major river in central-northern Thailand.

Satellite-based precipitation products are becoming available at very high temporal and spatial resolutions, which has accelerated their use in various hydro-meteorological and hydro-climatological applications. Because the quantitative accuracy of such products is affected by numerous factors related to atmospheric and terrain properties, validating them over different regions and environments is needed. This study investigated the performance of two high-resolution global satellite-based precipitation products: the climate prediction center MORPHing technique (CMORPH) and the latest version of the Integrated Multi-SatellitE Retrievals for the Global Precipitation Mission (GPM) algorithm (IMERG), V06, over the United Arab Emirates from 2010 through 2018. The estimates of the products and that of 71 in situ rain gauges distributed across the country were compared by employing several common quantitative, categorical, and graphical statistical measures at daily, event-duration, and annual temporal scales, and at the station and study area spatial scales. Both products perform quite well in rainfall detection (above 70%), but report rainfall not observed by the rain gauges at an alarming rate (more than 30%), especially for light rain (lower quartile). However, for moderate and intense (upper quartiles) rainfall rates, performance is much better. Because both products are highly correlated with rain gauge observations (mostly above 0.7), the satellite rainfall estimates can probably be significantly improved by removing the bias. Overall, the CMORPH and IMERG estimates demonstrate great potential for filling spatial gaps in rainfall observations, in addition to improving the temporal resolution. However, further improvement is required, regarding the overestimation and underestimation of small and large rainfall amounts, respectively.