Variations in rainfall and extreme event indices in The wettest part of Ethiopia

Changes in daily rainfall indices in the wettest (south-western) part of Ethiopia, commonly referred to as ‘year-round’ rainfall region were examined, by using records from nine stations over the period 1978–2007. Sixteen rainfall and dry spell related indices were defined and analyzed for trends; least squares regression was used to quantify trend and Kendall’s tau test was used to test statistical significance of trend. A complex picture of rainfall variability emerges from the analysis. Only one station (Gore) shows a statistically significant decline. The same station (Gore) shows significant decreasing trends in very wet day (R95p) and extremely wet day (R99p) amounts, whereas another station (Jimma) shows significant increasing trends in these parameters (total rainfall, very wet day and extremely wet day amounts); the other stations show no significant trends in these indices. Two of the stations (Asendabo and Sokoru) show statistically significant increasing trends in the maximum number of consecutive dry days. The results generally support previous studies in Ethiopia that there are no consistent patterns or trends in daily rainfall characteristics or seasonal rainfalls with the additional finding that choice of study stations strongly influences results of trend analysis. This suggests that regional scale conclusions may not be provided by analysis of few selected stations, given the high level of spatial variability at sub-regional scales in Ethiopia

Vulnerability of Smallholder Farmers’ to Climate Change and Variability in the Central Highlands of Ethiopia

This study investigates vulnerability of smallholder farmers to climate change and variability in three districts (Basona Werana, Efratana Gidim and Menz Gera Meder) located in different agroecological zones (AEZs) in the central highlands of Ethiopia. Household level data about livelihood capitals and climate related variables were used to develop vulnerability indices and determine vulnerability patterns across the study area. Our results identify Basona Werana as the most vulnerable in terms of physical and financial capital indicators while Efratana Gidim is the most vulnerable in natural capital indicators and climate factors. Vulnerability score of 3 out of the 6 indicators are the least for Menz Gera Meder. Statistically significant differences of vulnerability are observed in 9 of the 39 subcomponents indicating differences in the level of vulnerability across agroecological zones. The findings have implications for planning and prioritizing adaptation interventions in the study area, while the methodology is applicable to other parts of rural Ethiopia as well.Keywords: climate change; vulnerability; farmer, North Shewa, Ethiopi

Why does accuracy assessment and validation of multi-resolution-based satellite image classification matter? A methodological discourse

This study presents a methodological discourse about how to validate the reliability of thematic maps derived from multi-resolution satellite-based image classification. Besides, the paper examines unbiased estimates of accuracy assessment using known sampling units. Landsat and spot images were used for lulc thematic layer extraction. These thematic layers together with reference data extracted from panchromatic aerial photo interpretation and ground survey were used as input datasets for accuracy assessment and validation analysis. For each lulc unit, a minimum of 50 reference samples were derived using a stratified random sampling scheme. Consequently, error matrices were generated to validate the quality of the 1973, 1995 and 2007 lulc maps. To improve sampling biases introduced due to the stratified random sampling reference data collection scheme, accuracy assessment indices including the producer’s, user’s and overall accuracy as well as Kappa coefficient of agreement were adjusted to the known areal proportion of map categories. The computed overall accuracy, corrected for bias using known marginal proportions of the 1973, 1995 and 2007 thematic layers were 88.12%, 89.95% and 92.27%, respectively. Also, 81.20%, 82.17% and 83.11% of Kappa coefficient of agreement were achieved from the 1972, 1995 and 2007 classifications, respectively. The findings show that high resolution aerial photos are good sources of  reference datasets in the absence of historical ground truth data for accuracy assessment analysis and the lulc classifications fulfilled the minimum of lulc classification standards of overall accuracy and Kappa coefficient of agreement. Consequently, all the lulc classifications could be used as an input for policy options for integrated land resource management practices in the watershed studied

Summer Rains and Dry Seasons in the Upper Blue Nile Basin: The Predictability of Half a Century of Past and Future Spatiotemporal Patterns

peer-reviewedDuring the last 100 years the Ethiopian upper Blue Nile Basin (BNB) has undergone major changes in land use, and is now potentially facing changes in climate. Rainfall over BNB supplies over two-thirds of the water to the Nile and supports a large local population living mainly on subsistence agriculture. Regional food security is sensitive to both the amount and timing of rain and is already an important political challenge that will be further complicated if scenarios of climate change are realized. In this study a simple spatial model of the timing and duration of summer rains (Kiremt) and dry season (Bega), and annual rain over the upper BNB was established from observed data between 1952 and 2004. The model was used to explore potential impacts of climate change on these rains, using a down-scaled ECHAM5/MP1-OM scenario between 2050 and 2100. Over the observed period the amount, onset and duration of Kiremt rains and rain-free Bega days have exhibited a consistent spatial pattern. The spatially averaged annual rainfall was 1490 mm of which 93% was Kiremt rain. The average Kiremt rain and number of rainy days was higher in the southwest (322 days) and decreased towards the north (136 days). Under the 2050–2100 scenario, the annual mean rainfall is predicted to increase by 6% and maintain the same spatial pattern as in the past. A larger change in annual rainfall is expected in the southwest (ca. +130 mm) with a gradually smaller change towards the north (ca. +70 mm). Results highlight the need to account for the characteristic spatiotemporal zonation when planning water management and climate adaptation within the upper BNB. The presented simple spatial resolved models of the presence of Kiremt and annual total rainfall could be used as a baseline for such long-term planning.Swedish International Development Cooperation Agenc

Drought characterization using different indices, theory of run and trend analysis in bilate river watershed, rift valley of Ethiopia

Droughts have become more powerful and frequent, affecting more people for longer periods than any other natural disaster, particularly in eastern Africa. The unprecedented climate change has increased the severity, duration, and frequency of droughts. The objectives of this study were to evaluate performances of different drought indices for spatiotemporal drought characterization in the Bilate river watershed that represents part of the rift valley drylands in Ethiopia. Historical data for 39 years (1981–2019) from seven stations were used for drought analyses using the following indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Reconnaissance Drought Index (RDI), enhanced Reconnaissance Drought Index (eRDI) with different time scale and Self-Calibrated Palmer Drought Severity Index (scPDSI). Among them, SPI, SPEI, RDI and eRDI with 6-month and 9-month time scales were found to be the best correlated drought indices to characterize the historical drought events. Then, using the selected drought indices, temporal drought analysis showed occurrence of major drought events in the years: 1984/85, 1999/2000, 2002/3, and 2009. Some of these years are well known as famine years in some parts of Ethiopia including the study area. The results revealed spatial variation the severity of drought with extreme droughts occurred in the southern part of the Bilate watershed. Application of the theory of run confirmed that the maximum severity and duration of drought were observed at the Bilate Tena station that is located in the southern part of the watershed; the most severe being observed on a 9-month scale during 1984/85. Hossana and Wulbareg stations showed the highest frequency of drought over the study period. The Mann-Kendal trend test statistics showed an increasing trend of drought conditions in the study watershed

Ensuring sustainable water security through sustainable land management: Research evidences for policy

Sustainable land management (SLM) practices is a key to reducing rates of land degradation and has proven to ensure water security by increasing soil moisture availability, decreasing surface runoff, decreasing soil erosion, increasing infiltration, and decreasing flood discharge. Land degradation is adversely affecting over 75% of the Earth's land surface and could exceed 90% by 2050. The rate of soil erosion will increase by 66% during the period 2015–2070. Over 85% of the land in Ethiopia is moderately to very severely degraded at an estimated cost of $4.6 billion annually. So far, only 18% of Ethiopia's cropland area is covered by SLM practices for the last 40 years of intensive interventions. Water security, in turn, is a powerful and multidimensional option that includes water availability, accessibility, use, and stability across time. In Ethiopia, though, the interconnections between SLM and water security are intimate and numerous, their linkage is very loose and yet to be understood. Ethiopia is among the 16 LDCs and is critically water-insecure, implying that abundant natural water availability does not necessarily ensure water security as it might be poor water quality, inaccessible, and unsafe. Hence, national and local level of SLM and water security linkages, impacts, and policy implications must come on board in the least developing countries like Ethiopia. Therefore, SLM-water security policy is crucial in successful SLM because governments/higher officials are capable of promoting well-informed water security decisions

Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia

CITATION: Shiferaw, H. et al. 2021. Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia. Scientific Reports, 11:2688,doi:10.1038/s41598-021-81776-6.The original publication is available at https://www.nature.comDense impenetrable thickets of invasive trees and shrubs compete with other water users and thus disrupt ecosystem functioning and services. This study assessed water use by the evergreen Prosopis juliflora, one of the dominant invasive tree species in semi-arid and arid ecosystems in the tropical regions of Eastern Africa. The objectives of the study were to (1) analyze the seasonal water use patterns of P. juliflora in various locations in Afar Region, Ethiopia, (2) up-scale the water use from individual tree transpiration and stand evapotranspiration (ET) to the entire invaded area, and 3) estimate the monetary value of water lost due to the invasion. The sap flow rates of individual P. juliflora trees were measured using the heat ratio method while stand ET was quantified using the eddy covariance method. Transpiration by individual trees ranged from 1–36 L/day, with an average of 7 L of water per tree per day. The daily average transpiration of a Prosopis tree was about 3.4 (± 0.5) mm and the daily average ET of a dense Prosopis stand was about 3.7 (± 1.6) mm. Using a fractional cover map of P. juliflora (over an area of 1.18 million ha), water use of P. juliflora in Afar Region was estimated to be approximately 3.1–3.3 billion m3/yr. This volume of water would be sufficient to irrigate about 460,000 ha of cotton or 330,000 ha of sugar cane, the main crops in the area, which would generate an estimated net benefit of approximately US$320 million and US$ 470 million per growing season from cotton and sugarcane, respectively. Hence, P. juliflora invasion in the Afar Region has serious impacts on water availability and on the provision of other ecosystem services and ultimately on rural livelihoods.https://www.nature.com/articles/s41598-021-81776-6Publisher's versio

Second supplement to the Federated Malay States Government Gazette of Friday, the 27th of February, 1920 (No. 1, Vol. XII).

The customs duties enactment, 1897 and 1898. The quarantine and prevention of disease enactment, 1903. The food control regulations, 1918