**1. Introduction**

Soil degradation is one of the most leading environmental challenges all around the world. It decreases land for agricultural activities and ultimately lead to less agricultural production. It also leads in the removal of top soil which reduces the fertility rate of that land [1–3]. Soil is a medium which has been threatened by several factors like soil erosion, decrease in organic matter, contamination. The regions having arid and semi-arid climatic conditions are more prone towards soil erosion [4]. It has influence on land degradation, water quality, sedimentation of rivers, infrastructural damages and on agricultural productivity [5, 6]. The causes for erosion include, agricultural

activities, urbanization, population explosion, climate change, infrastructure, mining activities and many other [7].

Short-term environmental and climatic change is resisted by most soils, but may undergo irreversible change such as large-scale erosion. Erosion of the soil is normally used to depict the adverse effects of man's utilization of soil resource, with soil being a valuable natural resource which is renewed really slowly. Soil erosion is induced by anthropogenic impact on land surface, whether in terms of deforestation, extreme cultivation or the misuse of the land. Rill and sheet erosion proves to be very dangerous form of soil erosion, resulting in an almost imperceptible but constant degradation of land under cultivation. Soil erosion proves to be disastrous natural phenomenon that threatens soil stability [8].

The identification and estimation of erosion risk zones is an important element in preventing land degradation. Among those elements the most important factors are the observation of soil forming factors of that particular region. In Pakistan, the phenomenon of soil degradation is also of utmost importance and is one of the major environmental challenges. Soil erosion has many impacts such as low agricultural productivity and sedimentation. The quantities of soil erosion depend upon the topography, vegetation, soil type, and climatic conditions. Pakistan is a dry land and lies in arid and semi-arid region. Eighty percent of the land in Pakistan is arid or semiarid, about 12% is dry sub-humid and the remaining 8% is humid. About two-third population in Pakistan are depended on this dry land for their livelihood. Dry lands of Pakistan are drastically affected by degradation of land and desertification because of poor and mismanaged land practices [9].

Soil erosion assessment, zonation and prediction are highly important in order to lessen soil loss [10]. Several soil erosion modeling approaches have been introduced to predict soil erosion in highland regions and to evaluate the transportation and deposition of sediments. Among these models, majority of the models were first introduced in United States based entirely on different equations. Later on, these equations were improvised and many new variables and factors were added. Some of the soil erosion models are, Modified Universal Soil Loss Equation (MUSLE) [11], Universal Soil Loss Equation (USLE), the Unit Stream Power – based Erosion Deposition (USPED) [9, 12], and the Revised Universal Soil Loss Equation (RUSLE) [13].

The RUSLE is a computer-based version of USLE. It has been modified by adding several new factors which include new set of rules and algorithms to compute the cover factor, for slope length and steepness factors. This study aims to spatially quantify the soil loss in Eastern Hindu Kush Region using RUSLE approach integrated with Remote Sensing and Geographic Information System (GIS).
