Soil Erosion Hazard in Errer Dembel Sub-Basin, in Shinille Zone of the Ethiopia Somali Regional State Yohannes Gerezihier Gebremedhin* Department of Natural Resources Management, Adigrat University, Ethiopia Submission: January 10, 2019; Published: February 05, 2019 *Corresponding author: Yohannes Gerezihier Gebremedhin, Department of Natural Resources Management, College of Agriculture and Environmental Sciences, Adigrat University, p.o.x., 50 Adigart, Tigray, Ethiopia Int J Environ Sci Nat Res 17(1): IJESNR.MS.ID.555951 (2019) 001 Research Article Volume 17 Issue 1 - February 2019 DOI: 10.19080/IJESNR.2019.17.555951 Int J Environ Sci Nat Res Copyright © All rights are reserved by Yohannes Gerezihier Gebremedhin Introduction Soil erosion, land degradation and desertification are terminologies commonly employed in describing the condition of an environment that is in disequilibrium and mainly are the result of man’s interaction with his surroundings. Accelerated soil erosion is often a problem where unsystematic or inappropriate land use prevails and can simply be defined as the process of removal or displacement of soil particles from one place to another by the forces of water and/or wind and mass slide. The continues removal of soil particles from a given area often leads to the complete removal of the nutrient rich top soil, reduction of the soil depth and its water holding capacity and thus in turn lead to reduced productivity [1]. Varieties of human activities disturb the land surface of the earth, and thereby alter natural erosion rates [2]. Land degradation, according to the United Nations’ Environmental Program’s (UNEP’s) definition of 1991 [3], implies reduction of resource potential by one or a combination of processes acting on the land. These processes include water erosion, wind erosion and sedimentation by those agents, long-term reduction in the amount or diversity of natural vegetation or decrease of crop yield where relevant and salinization and sodification of soils. Therefore, soil erosion is the major causes of land degradation in Ethiopian in general and Errer-dembel sub-basin area in particular. Soil loss rates for different land unit classes (land cover types) were estimated using the Universal Soil Loss Equation (USLE) adapted for Ethiopian conditions. Hurni [4] noted that these results correlated well with test-plot measurements made by the Soil Conservation Research Project (SCRP), although, as noted previously, such estimates can greatly overstate the net impact of erosion on soil loss, because of re-deposition of soils elsewhere in the landscape. Hurni reports [4] gross soil losses and hence the loss figures are not net of soil re-deposition and soil formation. Soil formation was separately reported so that gross losses could be compared to soil formation, as an indicator of sustainability. Estimation of soil formation was “based on assumptions of soil regeneration as a function of geology and soils (unit and depth), slope gradient, climate (temperature, rainfall, and length of growing period), and land use” [4]. Hurni also noted that the model was not validated thoroughly with field data. Water erosion is the dominant form of soil erosion in the Errer-dembel sub-basin. Slight wind erosion problem exists particularly on the central and north west of the sub basin around Aysha-Dewele watershed of the sub basin. Accelerated erosion is caused by the activities of man and is responsible for depleting soil productivity, destroying land and filling reservoirs with sediments. Abstract Human activities disturb the land surface of the earth, and thereby alter natural erosion rates. Errer-dembel sub-basin is located within awash-basin in Shinille zone of the Ethiopia Somali region. Soil erosion hazard and land degradation were comprised from field measurements, survey and investigation of the area were made. Various forms of erosion and land degradation exist in the basin with varying level of severity and extents were found. The types of land degradation observed in the basin include water erosion, wind erosion, soil fertility decline, sedimentation/soil burial, de-vegetation and rock outcrop. the causes to these include poor farming practices, overgrazing in the range lands, clearing of forest for charcoal making and animal feed, forest and bush burning and lack of awareness. A maximum soil loss of 40.80tha -1 yr -1 and minimum of 0-3tha -1 yr -1 is estimated in the sub-basin. Similarly, the soil loss tolerance limit estimates, indicated high values 7tha -1 yr -1 for the high rainfall areas with intensive cultivation, and low values of 1-4tha -1 yr -1 in the low rainfall areas in the north of the basin, owing to the prevailing unfavorable conditions involved in soil formation processes. Soil formation rate is in the range of 0.5-4tonsha -1 yr -1 . This indicates that the soil loss is much beyond the tolerable level in the southern and south eastern part of the sub-basin with the resultant high index of erosion hazard. Thus, the soils of Errer-dembel sub-basin are found to be highly susceptible to soil erosion under any circumstances. Keywords: Soil erosion hazard; Soil erosion; Soil degradation; Errer-dembel sub-basin; Ethiopia Somali regional state