Characteristics of hydrological extremes in Kulfo River of Southern Ethiopian Rift Valley Basin

Abstract

Hydrological extreme events such as floods and drought are common in Ethiopia which eventually causes environmental hazards. Kulfo River is one of Southern Ethiopian Rift Valley Basin that has experienced flooding for years. Therefore, this study aimed characteristics of hydrological extremes in the Kulfo River, which is important for effective drought and flood monitoring and early warning systems. The hydrological drought was assessed using the streamflow drought index (SDI). Flood frequency distribution (FFD) software package was deployed to determine the flood frequency curve of the Kulfo River. The goodness-of-fit test results showed that the Generalized Extreme Values (GEV) distribution was found the best-fit probability distribution model in the Kulfo River, while the results of SDI values showed that extreme drought events were observed in 1991, 1992, and 2014 with magnitudes ranging from − 2.04 to − 2.7, − 2.0 to − 2.3, and − 2.10 to − 2.24, respectively, which cause reduction of lake level, lowing of groundwater level, and decreased the amount of river flow. SDI value indicated 6-year drought duration has occurred with the relative frequency of 20% in the 3-and 6-month timescales. The flood frequency results show the lowest probability of having flood magnitude has affected the river morphology. The study provides valuable information for policy and decision makers to implement different adaptation and mitigation measures for extreme hydrological events in the Kulfo River.

Remote sensing, GIS, and RUSLE in soil loss estimation in the Kulfo river catchment, Rift valley, Southern Ethiopia

“…The catchment receives 620-1250 mm of rain per year. The mean annual flow is estimated to range between 1.8 and 22.8 m 3 /s (for the observation period 1985-2014) (Yisehak et al, 2020). Cambisols, ferralsols, regosols, and fluvisols are the four primary soil types found in the Kulfo watershed.…”

“…Soil erosion is a severe threat to the food security of Africa, Asia, and other developing countries (Shiferaw, 2011). In Ethiopia, rainfall impacts on soil erosion are notably severe (Jothimani et al, 2020a;Yisehak et al, 2020). In the Ethiopian highland, 27 million hectares of land have been significantly degraded; among these, 2 million hectares of land are classified as an unrecoverable state (Hurni, 1988).…”

Comparing surface water supply index and streamflow drought index for hydrological drought analysis in Ethiopia

“…This implies that SDI is more suitable for hydrological drought analysis in this basin than M1SWSI. Because other studies also show that [ 36 , 77 ] the area is frequently affected by severe drought but M1SWSI minimized the impact of drought in the area due to the combination of different surface water sources.…”