Abstract

Population growth and human activities have resulted in drastic changes in land use in many areas of the world, including the Hyrcania region in northern Iran. Land-use changes affect the hydrological processes of water basins. This study evaluated the effect of land-use changes on runoff over 15 years in the Haraz River basin located in Hyrcania using remote sensing data and GIS analyses. The annual precipitation of the region is 66.5 cm. Two Landsat images were used to develop land-use maps for 1996 and 2011. Original image features, their principal components, and vegetation indices were used to classify the two Landsat images into different land-use categories. Runoff was predicted from precipitation, land use, and hydrological soil groups, using the SCS-CN model (the “curve number” approach). During the 15 years, 62.4% of the area remained unchanged and 37.6% had undergone a land-use change. The highest average runoffs were obtained for bare land (14.1–14.5 cm/year) and residential land (10.4–11.4 cm/year), and the lowest for dense forest (2.5–2.6 cm/year) and first-grade rangeland (2.8–3.1 cm/year). The volume of annual runoff increased by 9% during 1996–2011 due to land-use changes. Runoff was estimated at 9.4% of precipitation in 1996, and 9.6% of precipitation in 2011. Most of the increase was related to the increased area of bare land and decreased area of rangeland. The study indicated that combined use of the SCS-CN approach, remote sensing data, and GIS tools allow cost-effective runoff estimation, helping watershed management. The results on the effect of land-use change on runoff can be seen as a warning for land-use managers and policymakers, who should aim at stopping and reversing the current land-use trends of the Haraz River basin.

Highlights

  • Land is an essential natural resource, both for humanity, and the maintenance of all terrestrial ecosystems [1]

  • This study used remote sensing to detect changes in land use and the Soil Conservation Service (SCS) curve number method to calculate the effect of land‐use change on water runoff

  • The present study indicates that the SCS‐curve number (CN) method integrated with remote sensing and GIS techniques can be used effectively in watershed management

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Summary

Introduction

Land is an essential natural resource, both for humanity, and the maintenance of all terrestrial ecosystems [1]. Increases in population density and human activities have caused increased demand for water, arable land, wood, grazing areas, and other types of resources [2,3]. Water is an indispensable resource and a key element in human liveli‐. Hood and socioeconomic development [4]. Ability may become a critical factor for human activities. Age water resources for their sustainable use [3]. Precipitation is the main source of water in the world.

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