Performance of bias corrected MPEG rainfall estimate for rainfall-runoff simulation in the upper Blue Nile Basin, Ethiopia

In many developing countries and remote areas of important ecosystems, good quality precipitation data are neither available nor readily accessible. Satellite observations and processing algorithms are being extensively used to produce satellite rainfall products (SREs). Nevertheless, these products are prone to systematic errors and need extensive validation before to be usable for streamflow simulations. In this study, we investigated and corrected the bias of Multi-Sensor Precipitation Estimate–Geostationary (MPEG) data. The corrected MPEG dataset was used as input to a semi-distributed hydrological model Hydrologiska Byråns Vattenbalansavdelning (HBV) for simulation of discharge of the Gilgel Abay and Gumara watersheds in the Upper Blue Nile basin, Ethiopia. The result indicated that the MPEG satellite rainfall captured 81% and 78% of the gauged rainfall variability with a consistent bias of underestimating the gauged rainfall by 60%. A linear bias correction applied significantly reduced the bias while maintaining the coefficient of correlation. The simulated flow using bias corrected MPEG SRE resulted in a simulated flow comparable to the gauge rainfall for both watersheds. The study indicated the potential of MPEG SRE in water budget studies after applying a linear bias correction

Integrating Socioeconomic Biophysical and Institutional Factors for Evaluating Small-Scale Irrigation Schemes in Northern Ethiopia

This paper characterizes and compares three types of small-scale irrigation scheme practices in Northern Ethiopia. A multidisciplinary survey approach, collecting information on socioeconomic, biophysical, and institutional aspects of irrigation by the smallholder farmers, was used to investigate and compare aspects of land, water use, and crop productivity, including farmer income and livelihood sustainability. The study was conducted in the Zamra catchment, a sub-basin of the large Tekeze river basin and Nile basin tributary. Three common small-scale irrigation scheme types, i.e., traditional diversion, modern diversion, and dam (reservoir) based irrigation, were compared using four pilot survey areas. From the total of 618 farmer households in the study areas, 242 farmers were selected using stratified random sampling and participated in the survey and research. More than 100 input data were collected from the farmers related to the biophysical, socioeconomic, and institutional factors affecting their work practice and livelihood. Focus group discussions were conducted with elders, the water users association committee, and women-headed households. Descriptive statistics and multivariate analysis were used for quantitative analysis. The result indicates a significant difference between the three irrigation schemes. One important conclusion of this study was that the explanatory value of a single factor (e.g., biophysical), as commonly done in irrigation research and assessment, was seldom sufficient to explain water use, crop yield, and farmer income. Institutional and/or socioeconomic drivers also played an important role in the entire farming practice, income generation, and livelihood of the farmers. This study highlighted the value-added of the multidisciplinary approach (socioeconomic, biophysical, and institutional) for the evaluation of small-scale irrigation practices and livelihood analysis of agricultural smallholders in climate-affected regions, such as the Northern Ethiopian highlands