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

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

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

Predicting land-use change and its impact on the groundwater system of the Kleine Nete catchment, Belgium

Land-use changes are frequently indicated to be one of the main human-induced factors influencing the groundwater system. For land-use change, groundwater research has mainly focused on the change in water quality thereby neglecting changes in quantity. The objective of this paper is to assess the impact of land-use changes, from 2000 until 2020, on the hydrological balance and in particular on groundwater quantity, as results from a case study in the Kleine Nete basin, Belgium. New is that this study tests a methodology, which couples a land-use change model with a water balance and a steady-state groundwater model. Although the averages found appear to indicate small changes in the groundwater system, spatial analysis shows that much larger changes are located near the major cities in the study area. Hence, spatial planning should take better account of effects of land-use change on the groundwater system and define mitigating actions for reducing the negative impacts of land-use change

Effect of Dates and Methods of Sowing with and without Hydropriming on Growth, Phenology and Yield of Sorghum under Semi Arid Conditions of Eritrea

A study was carried out at the research farm of Hamelmalo Agricultural College during summer 2015 to study the effect of dates and methods of sowing with and without hydro-priming on growth, development and yield of sorghum. The experiment consisted of 2 factors- three dates of sowing viz. D0 (Sowing before the onset of first summer rain, June 30), D1 (Sowing with the onset of first summer rains, July 7) and D2 (Sowing after the onset of summer rains, July 14) and three methods of sowing viz. SP (Direct sowing with hydro seed priming), TR (Transplanting) and DS (Direct sowing without hydro seed priming). The experiment was conducted in split plot design with 4 replications by keeping dates of sowing in the main plots and methods of sowing in the sub plots. The data on growth parameters, crop phenology, yield components and yield were recorded. The data were analysed using GENSTAT software and inferences were drawn by using LSD at 5% level of significance. Sowing methods significantly affected leaf area and leaf area index but sowing dates and their interaction with sowing methods did not show significant difference. Stand count, plant height, phenological parameters, thousand grain weight, grain and biomass yield were significantly affected by the sowing dates and methods but no significant difference in their interaction on all the parameters except in stand count and phenological parameters. Sowing before the onset of first summer rains (D0) resulted in significantly highest grain yield. Among the sowing methods, transplanting resulted in significantly higher grain yield seconded by direct sowing with hydro seed priming. Transplanting is less profitable and practicable as it is more laborious and difficult to apply in larger areas

Forecasting land-use change and its impact on the groundwater system of the Kleine Nete catchment, Belgium

International audienceLand-use change and climate change, along with groundwater pumping are frequently indicated to be the main human-induced factors influencing the groundwater system. Up till now, research has mainly been focusing on the effect of the water quality of these human-induced changes on the groundwater system, often neglecting changes in quantity. The focus in this study is on the impact of land-use changes in the near future, from 2000 until 2020, on the groundwater quantity and the general hydrologic balance of a sub-catchment of the Kleine Nete, Belgium. This study tests a new methodology which involves coupling a land-use change model with a water balance model and a groundwater model. The future land-use is modelled with the CLUE-S model. Four scenarios (A1, A2, B1 and B2) based on the Special Report on Emission Scenarios (SRES) are used for the land-use modelling. Water balance components, groundwater level and baseflow are simulated using the WetSpass model in conjunction with a MODFLOW groundwater model. Results show that the average recharge slowly decreases for all scenarios, the decreases are 2.9, 1.6, 1.8 and 0.8% for respectively scenario A1, A2, B1 and B2. The predicted reduction in recharge results in a small decrease of the average groundwater level, ranging from 2.5 cm for scenario A1 to 0.9 cm for scenario B2, and a reduction of the total baseflow with maximum 2.3% and minimum 0.7% respectively for scenario A1 and B2. Although these average values do not indicate significant changes for the groundwater system, spatial analysis of the changes shows the changes are concentrated in the neighbourhood of the major cities in the study areas. It is therefore important for spatial managers to take the groundwater system into account for reducing the negative impacts of land-use and climate change as much as possible

Evaluation of Germplasm of Pearl Millet (Penissetum glaucum L.) for Agronomic, Physiological and Biochemical Traits under Semi-arid Conditions of Hamelmalo

A field experiment was conducted at the experimental farm of Hamelmalo Agricultural College during summer 2017, to evaluate the agronomic, physiological, and biochemical performance of the collected Eritrean germplasm of pearl millet. A total of 16 accessions were tested, out of which 2 were improved varieties included as a check. The experiment was laid out in 4 x 4 Simple Lattice Design with Randomized Block using 4 replications with a gross plot size of 3.0 m x 1.2 m, row to row spacing of 75 cm and plant to plant spacing of 30 cm. The data collected were Agronomic parameters (growth, development, yield, and yield contributing characters); Physiological parameters (Relative water content and Water Use Efficiency); and Biochemical parameters (crude fat, crude fiber, protein content, TSS, and ash content). The data were analyzed using GENSTAT software and correlation analysis was worked to see the positive and negative contribution of agronomic, physiological, and biochemical attributes. The results of the study showed that Bariyay908 and Kona being statistically at par with Bariyay 910, Hagaz, Zibedi, Shleti, Delkata, Tokroray, and Kunama produced significantly higher grain yield. However, among these Baryay908 because of its superior agronomic characteristics, lower incidence of downy mildew, relatively higher water use efficiency and higher crude protein content were found to be comparatively superior to the check improved varieties Kona and Hagaz. Grain yield has shown a positive and significant correlation with harvest index, number of seeds per panicle, panicle length, leaf area and water use efficiency. These promising accessions need to be further tested for future breeding programs to develop varieties higher in productivity and resistant to downy mildew under semiarid conditions of Eritrea

Evaluation of Sorghum (Sorghum bicolor) Landraces for Drought Tolerance Using Morphological and Yield Characters under Rainfed Conditions of Sub Region Hagaz, Eritrea

Sorghum is an important food crop in Eritrea where it is widely grown in the mid and low lands, of semi-arid regions. Eritrea being the center of origin of sorghum, a large variability exist in its landraces being grown by the farmers since generations. In order to improve the productivity of sorghum under moisture stress conditions, it is imperative to evaluate these landraces for drought tolerant characteristics and their use for further crop improvement programmes. Therefore, a field study was conducted in a randomized complete block design with three replications to estimate the extent of genetic variability of 20 sorghum genotypes for moisture stress tolerance using various morphological, phenological, yield and yield related parameters under rainfed conditions at Hagaz Research Station. Significant difference was observed for almost all the characters in the individual analysis of variance suggesting that these sorghum accessions were highly variable. Accessions EG 537, EG 1257, EG 849, EG 791, EG 783 and EG 813 showed promising results for post flowering drought tolerance, grain yield and stay green traits. Higher PCV and GCV were also obtained in parameters like plant height, leaf area, biomass, peduncle exertion, panicle length, and grain yield and panicle weight. The genotypes also exhibited varying degrees of heritability estimates. Characters such as plant height, panicle length, days to flowering and maturity showed higher heritability. Cluster analysis revealed that sorghum landraces were grouped on the basis of their morphological traits and geographical sites. 77.3% of the total variation of sorghum landraces was contributed by the first four principal components analysis having Eigen value > 1. Overall, the current study confirmed that EG 537, EG 849, EG 1257, EG 791, and EG 813 are drought tolerant sorghum landraces during post flowering stage