نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار، بخش تحقیقات خاک و آب، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان کردستان، سازمان تحقیقات، آموزش و ترویج کشاورزی،

2 دانشیار گروه کشاورزی، دانشگاه پیام نور، تهران، ایران

3 دانشیار، بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان کرستان، سازمان تحقیقات، آموزش و ترویج

چکیده

فرسایش و پیامدهای ناشی از آن، با تشدید بهره‌برداری انسان از طبیعت از اوائل قرن بیستم، اثرات منفی خود را بر اکوسیستم حیاتی وارد ساخته است. به منظور جلوگیری از تشدید فرسایش خاک در مدیریت حوزه‌های آبخیز، برآورد فرسایش، تعیین منبع تولید و اشکال فرسایش، ضروری است. در این پژوهش با بررسی داده‌های مکانی و بازدیدهای صحرایی، میزان رسوب و اشکال مختلف فرسایش حوزه آبخیز خورخوره در استان کردستان مورد بررسی قرار گرفت. جهت برآورد رسوب حوضه از روش ترسیم منحنی سنجه رسوب استفاده شد. همچنین برای بررسی انواع فرسایش، نقشه‌های توپوگرافی، زمین‌شناسی و عکس‌های هوایی منطقه مورد مطالعه، جمع‌آوری و با ادغام لایه‌های زمین‌شناسی و ژئومورفولوژی در سامانه اطلاعات جغرافیایی، تعداد 68 زیرحوضه تعیین شد. سپس با بازدید صحرایی، نسبت به امتیازدهی به روش BLM در هر واحد کاری جهت تعیین شکل فرسایش اقدام شد. نتایج نشان داد مقدار رسوب معلق کل حوضه برابرton/yr 2990 و مقدار بار کف حدود %15 بار معلق می‌باشد. مقدار تولید رسوب ویژه حوضه حدودton/km2.yr 3/25 برآورد شد. نتایج نشان داد در تعدادی از زیرحوضه ها تمامی اشکال فرسایش سطحی، شیاری، خندقی، آبراهه‌ای و رودخانه‌ای در حال رخ دادن است. همچنین غالب مساحت حوضه در کلاس حساس و خیلی حساس به فرسایش قرار دارند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Determination of Soil Erosion and Sediment Estimation of Khorkhoreh Basin using Sediment Rating Curves

نویسندگان [English]

  • Mohammad Hossein Sedri 1
  • Mehdi Karami Moghadam 2
  • Ata Amini 3

1 Assistant Professor, Soil and Water Research Department, Kurdistan Agricultural and Natural Resources Research and Education Center, AREEO, Sanandaj, Iran

2 Associate Professor, Department of Agriculture, Payame Noor University (PNU), Tehran, Iran [email protected]

3 Associate Professor, Soil Conservation and Watershed Management Research Department, Kurdistan Agricultural and Natural Resources Research and Education Center, AREEO, Sanandaj, Iran

چکیده [English]

Introduction



In order to plan and recognize the destructive condition of the watershed, it is indispensable to know the extent of erosion and sedimentation produced from each basin. In their studies on soil erosion assessment using WEPP model and Geographical Information System (GIS), Landi et al. (2011) specified that soil loss estimated by this model is largely correlated with data estimated by MPSIAC model. Furlan et al. (2012) deliberated on management options for runoff reduction and sediment production in southeastern France using hydrology simulation and erosion. In recent years, Khorkhoreh basin in Kurdistan province has tackled a severe water erosion. A review of previous studies show that neither research nor estimation has been performed so far on the erosion type and its amount in the basin. In the current investigation, the amount of basin erosion was estimated using measured data. Then, by combining the results of spatial data at the subbasin level, the erosion types in the whole basin were determined and the quantitative results of sediment production were presented.

Methods

This study was accomplished on Khorkhoreh watershed spanning an area of 42769.8 ha. Researches indicated that the sediment statistics of Qabqablo station had good homogeneity, hence the use of this station. Topographic and geological maps and aerial photographs of the study area were collected from the reference sites and maps. Then, by integrating geological and geomorphological layers in GIS and removing polygons under 6 ha, 24 working units and 68 sub-basins were attained. To identify the erosion type through field visit, the Bureau of Land Management (BLM) scoring was carried out in each work unit. To prioritize different basins in terms of erosion types, the map of hydrological units was combined with that of basin erosion types in ArcView environment and accordingly, the area of different erosion types was determined for each sub-basin.

Results

Using sediment curve, the amount of total suspended load in the basin was obtained as 2990 ton/yr. One of the parameters used in comparison among different basins in terms of erosion rate is specific sediment yield. The total load of the river is obtained by the sum of the bed load and suspended load. With the calculations performed, the amount of specific sediment yield in Khorkhoreh basin was found to be 25.3 ton/km2. All types of erosion can be seen in many portions of the basin, while most of the basin area belong to the sensitive and very sensitive to erosion classes. The most important factors influencing the development of various erosion types and sediment yield in Khorkhoreh basin include geological formations, climate and precipitation, topographic conditions, soil status and land use. Existence of various formations with different sensitivity to erosion has caused the development of different erosion types in the basin.



Conclusion

In this study, the rate of sediment and erosion types of Khorkhoreh watershed were investigated. Erosion types and their severity were determined via field studies and completion of BLM form. The most important results of this research are as follows:

(1) The suspended load in the whole basin is 2990 ton/yr with regard to the measured sediment curve. Also, the bed load is about 15% of the suspended load. (2) The specific sediment yield in the basin was estimated as 25.3 ton/km2.yr. (3) Examination of erosion types showed that in most of the basin’s working units, all types of erosion such as Sheet erosion, Rill erosion, Gully erosion, Channel erosion, and Stream Bank erosion can be observed.



Key Words: Kurdistan Province; Sedimentation station; Soil protection; Mechanical erosion

کلیدواژه‌ها [English]

  • Kurdistan Province
  • Sedimentation station
  • Soil protection
  • Mechanical erosion