Comparing global precipitation data sets in eastern Africa: a case study of Kilombero Valley, Tanzania

Abstract

ABSTRACT:In the face of limited or no precipitation data, global precipitation data sets (GPDs) may provide a viable alternative to gauge or ground radar data. This study aims to provide guidance to the choice of GPDs targeting scales relevant to water resources management in data poor regions.Specifically, the 34 000 km 2 Kilombero Valley in central Tanzania, where water resource management is seen as integral to poverty reduction and food security, is used as a case study for performance evaluation of seven GPDs and their ensemble mean against the Tropical Rainfall Measuring Mission (TRMM) multi-satellite precipitation analysis research-grade product v7 (TRMMv7 . Standard statistical performance measures and spatial patterns were evaluated for the common overlap time period 1998-2010. For this region, the principal seasonality of the climatology was well represented in all GPDs; however, the intraseasonal variability and the spatial precipitation patterns were less well represented. The ensemble mean and GPCC had the best performance with regard to the analysis of the time series while CMORPH and GPCC had the best performance with regard to the spatial pattern analysis. These results indicate that the spatial scale intended for application is a major factor impacting the suitability of a given GPD for hydrometrological studies that form a basis for development of water management strategies.

Sustainability in the Food-Water-Ecosystem Nexus: The Role of Land Use and Land Cover Change for Water Resources and Ecosystems in the Kilombero Wetland, Tanzania

“…The plain is geologically described by sedimentary basin infillings forming a seasonal alluvial floodplain geomorphic wetland type dominated by fluvisol soils [34]. The regional climate is characterized as sub-humid tropical with an average daily temperature of around 22-23 • C and annual precipitation of about 1200-1400 mm [35]. The bimodal rainy pattern comprises a short rainy season (November-January) and a long rainy season (March-May) with a distinct dry season from July until October.…”

Increasing the Accuracy of Runoff and Streamflow Simulation in the Nzoia Basin, Western Kenya, through the Incorporation of Satellite-Derived CHIRPS Data

“…However, although SWAT developers recommend the CFSR dataset, a study comparing different precipitation products in a watershed in eastern Africa found that the CFSR dataset in particular had poor spatial correlation in comparison to satellite-derived and interpolated gauge precipitation datasets. In addition, the size of the Nzoia Basin (12,000 km 2 ) may not be suitable for the use of reanalysis data without downscaling the data [27]. …”

“…It should be noted that since the CHIRPS dataset was first published in 2015, there are very few studies that evaluate and compare the CHIRPS dataset with similar global precipitation datasets. Even a recent study in eastern Africa from 2016 [27] comparing global precipitation datasets as an alternative to gauge data did not include the CHIRPS dataset in their analysis. Although not geographically relevant to this study, Duan et al [29] compared three different types of precipitation products for a small watershed in Italy: interpolated gauge station information like the Global Precipitation Climatology Centre (GPCC) data, datasets based off of numerical weather predictions and atmospheric models like the CFSR product, and datasets created from a blend of satellite-derived information and gauge station information like TRMM and CHIRPS.…”

Assessing seasonal land cover dynamics in the tropical Kilombero floodplain of East Africa

“…The region experiences bimodal rainfall with an annual rainfall of 1200 to 1400 mm and a mean annual temperature of 23°C to 25°C. 34 The main subsistence farming practiced in the area includes maize in relatively dry conditions and rice in naturally inundated areas. Both largeand small-scale farmers practice sugarcane farming.…”