Evaluating the Performance of HEC-HMS and SWAT Hydrological Models in Simulating the Rainfall-Runoff Process for Data Scarce Region of Ethiopian Rift Valley Lake Basin

A number of physically-based and distributed watershed models have been developed to model the hydrology of the watershed. For a specific watershed, selecting the most suitable hydrological model is necessary to obtain good simulated results. In this study, two hydrologic models, Soil and Water Assessment Tool (SWAT) and Hydrological Engineering Centre-The Hydrologic Modeling System (HEC-HMS), were applied to predict streamflow in Katar River basin, Ethiopia. The performances of these two models were compared in order to select the right model for the study basin. Both models were calibrated and validated with stream flow data of 11 years (1990-2000) and 7 years (2001-2007) respectively. Nash-Sutcliffe Error (NSE) and Coefficient of Determination (R2) were used to evaluate efficiency of the models. The results of calibration and validation indicated that, for river basin Katar, both models could simulate fairly well the streamflow. SWAT gave the model performance with the R2 > 0.78 and NSE > 0.67;and the HEC-HMS model provided the model performance with the R2 > 0.87 and NSE > 0.73. Hence, the simulated streamflow given by the HEC-HMS model is more satisfactory than that provided by the SWAT model.

Response of Tef (<i>Eragrostis tef</i>(Zucc.) Trotter) to Balanced Fertilizer in Wolaita Zone, Southern Ethiopia

Tef is grown as an important domestic cereal in Ethiopia. Currently, global attention is given for it particularly as a “health food” due to the absence of gluten and gluten like proteins in its grains. Regardless of its wider adaptation, productivity of tef is low in the country with the national average grain yield of 1.379 tons·ha-1. This is mainly because of low soil fertility and severe organic matter depletion intensified by low rate of chemical fertilizer application. This study was conducted to evaluate effects of balanced fertilizers on the yield, yield components of tef and to determine economic feasibility for tef production in Wolaita. The experiment was laid out in a randomized complete block design (RCBD) with sixteen treatments replicated three times. The treatments consist of factorial combinations of four rates of K (Potassium) (0, 25, 50, and 100 kg/ha) and four rates of NPSB (Nitrogen, Phosphorus, Sulfur and Boron) (0, 50, 100, 200 kg/ha) fertilizers. Fertilizer types such as urea (46-0-0), NPSB (18.9-37.7-6.95-0.1) and K (0-0-60) were used as a source of nutrients. The soil analysis result indicated that, most of the nutrients are below optimum level to support the potential crop production. This may be related with reduced farm management practices and continuous cropping with little or no fertilizers input. In this study, it was found that, the combined application of NPSB and K fertilizers had a significant effect on growth, yield and yield components of tef. Among the treatments studied, NPSB (100 Kg/ha) and K (50 Kg/ha) gave greater grain yield. Furthermore, this treatment enhanced growth and yield related parameters compared to the control treatment. Thus, it is conceivable to recommend each to attain greater grain yield of tef in the study area. However, it is desirable to undertake further research across soil type, years and locations to appeal comprehensive recommendation on a wider scale.