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1 Effects of "Drought" on "Wind Eroding and Erosion" in Sistan Region with use of Satellite Multiple Images M. Ranjbar 1 *, F.Iranmanesh 2 1.Faculty Board Member of Department of Geography, Islamic Azad University, Shahre Rey Branch,Tehran, Iran 2.Faculty Board Member of Water and Soil Research Centre, Tehran,Iran Corresponding Author:dr.mranjbar@gmail.com Abstract- Sistan region centralized in Zabol county is a broad plain which is located in northeast of Sistan and Baloochestan Province in east of Iran. One of the main characteristics of this plain is having sand and dust storm. Although sand and dust storms have occurred in Sistan region since the past up to now, it has been intensified due to consecutive droughts and blocking water of Kajaki dam leading to dryness of plains and Hirmand river bed. This caused many farmlands and susceptible lands to be subjected to deflation and transfer of the soil surface separates or burial of these separates under sands due to movement of drifting sand. Effects of such phenomenon caused to decrease income, reduce yields, destroy farmlands, decrease capacity of pasture, increase sediment load of the rivers and increase flood, increase water salinity, decrease vegetation cover, and wildlife and immigration, air pollution and respiratory problems. In this research, wind erosion and surface of the regions subject to wind erosion has been studied in addition to study of climatic, hydrological and agricultural drought. Therefore, some images with high coverage and repeatability are needed. For this purpose, Advance Very High Resolution (AVHRR) images from NOAA and MODIS sensor from TERRA which have the above specifications and receive broad interval of radiation energy in visible and invisible spectral zones were used. Results show that drought and dryness of plains especial Sabori plain are regarded as the most important place of harvesting and centre of storms and Poozak and Hirmand plains are of high importance after this plain. Deserted farmlands are of other regions susceptible to wind erosion due to drought. Key words: Sistan, Erosion, Satellite Multiple Images, Drought, Zabol, Plain. I. Introduction World population growth with rate of 7% indicates that food production should increase continually to prevent from food shortage. On the other hand, dryness and drought are the most important environmental stressful factors which make production of yields problematic. Occurrence of drought phenomenon depends on changes and fluctuations of rainfall and temperature. Although more than 5 million hectares of the land in the country are dominated by deposits resulting from storms and wind erosion, unfortunately, limited studies have been done in this field. Phenomenon of drought has occurred frequently in the past years in our country and especially in Sitan region and has shown undesirable effects and consequences. In this research, images and images mixing as well as climatic data have been used in addition to visual interpretation methods. Research methodology and its executive stages: data and information used in this research can be divided into six major groups. 1. Preparation of topographical images 1:50000 and 1: relating to old and new publication and Preparation of NOAA and MODIS images relating to the storms occurring in the recent years 2. Preparation of statistics of meteorological stations in zone of the plan 3. Digitalization of topographical plans and required layers in one of the geographical information system media (GIS) 4. Laboratory methods for processing images relating to the storms occurring in the recent years 4.1. Draft of ground control points (GPCs) 4.2. Geometrical corrections 4.3. Radiometric corrections 4.4. Use of visual interpretation methods for images such as spectral inspection, preparation of visual colorful images in different ways (OIF method and relieves reflective behavior) 4.5. Mixing images resulting from visual interpretation methods with other information layers of paragraph 2 such as layers of villages, cities, roads, flood plains etc 4.6. Conclusion and primary assessment of the occurring storms, expansion of the storms, their affected regions, determination of homogenous regions in terms of dust 5. Using statistics of wind of synoptic stations in the region, analysis of speed readings and instantaneous direction of wind in a day with regard to the available statistics, analysis of winds in different groups of wind speed, determination of wind speed in different heights with use of experimental relations and drawing diagram of wind speed in height, analysis of region winds for determining intensity and continuity of dominant winds and drawing compass card[6]. 6. Determination of erosive winds and its relationship with expansion of erosion and storm in the region II. Studied region position: ISSN: ISBN:

2 Sistan district with area of,117 sq km is located in northern Zabol county is a broad plain which is located in northeast of Sistan and Baloochestan Province and in east of Iran and is level and blocked zone which has been comprised of old and present delta alluvia of Hirmand river. Fig 1: geographical position map of the studied region II. Natural geography of the studied region: Sistan plain is extension of Helmand block in general geological terms. This plain which is Harirood fault is located in west is the marine residue of Tertiary which has been formed as pit due to tectonic movements and the last alpine orogenic phase (Pasadena). Then it has been filled due to accumulation of deposits and faults resulting from running waters (especially Hirmand). This plain is an alluvial deposit plain and freshwater spring. It seems that sedimentary basin is subsiding while receiving deposits and this continues at present. Thickness of deposits is 2500 m except in Zabol which has high thickness of hard block of infrastructure [10]. On the basis of the performed studies, Sistan is classified as desert and dry climatic zone. Average rainfall in Zabol and Zahak stations is 65 mm and 51.2 mm respectively and average temperature is 22.2 and 21.3 [3]. Relative humidity in the region is very low and is fluctuating averagely between 13 and 50%.[11],[4],[7]. The most important rivers which supply water are Hirmand Harirood-Rood Khoshk-Farah Rood- Khaspas Rood and Khash Rood Bandan Rood and Rood Shoor among which Hirmand river is of special importance. Intensive drought between 1970 and 1971 and cut of Hirmand water flow and as a result dryness of plains caused irreparable damage to animal husbandry and agriculture of the region [14],[13]. Groundwater sources in are limited in Sistan plain. Average depth of groundwater is about 50 to 0 cm from ground surface and is comprised of saline and brackish small undersurface aquifers. Sistan plain is located on margin of a hard block which is called Helmand block. Foundation of Helmand block has been hardened due to Hercynian movements and has been turned into platform. Sistan plain is covered by Neogene lacustrine deposits and Quaternary alluvia. Thickness of its deposits around Zabol is about 2500 m. high thickness of deposits indicates continual subsidence of the basin floor during quaternary. Surface of plain is smooth and has mild slope. Its general slope is from southeast to Hamoon pit located in northern part of the plain. Smoothness of the plain surface is based on horizontal structure of Neogene and Quaternary layers because Pasadenian movements could have not create tangible changes in Neogene deposits due to resistance of hard block of infrastructure[7],[15]. Longitude of 60 º 24' to 61 º55'. Sistan region centralized in part of this province between latitude of 30º 15' to 31 º 30' and Average Height of Sistan plain is 500 m and its highest point is Khajeh Mountain with height of 595 m. Sistan plain lacks aquifer. The said pits and depressions of basic surface of drain of the surrounding bottom lands and rivers especially Hirmand river. Height of pits floor is between 471 and 477 m. some swamps have covered the river as the band with variable widths. In addition to plains, major geomorphologic units of Sistan region include mountain plain, piedmont zones, plateaus and depressed plains of Zabol, river terraces and wind relieves have been identified in the region. Piedmont unit has been comprised of four subunits [15]. Combined fans (Bahada): There are three main fans in the region which have been created from south to north by Harmak, Torsh Ab and Shoor Rivers. Among these three fans, there are smaller fans. Pebbly plain: in these plains, fine particles have been carried due to action of wind and coarse grains have remained and desert pavement has been created[17]. Bottom lands: plains covered by deposits carried by water flows. Depression of this plain is about 20 m and is separated from plateau unit with wall which is probably slickenside. This unit is location of Zabol city and its related villages and farmlands of Hirmand Delta are located in this section. The subunits known in this unit are as follows: inselberg of Khajeh Mountain, Hirmaned Delta, Hamoon lakes, and phenomena resting from wind. The most important wind deposits of the region have been identified around Niatak and Maleki Miankangi, Ghaleh No and Jezink [11],[4]. Due to fluctuations of humid and frosty periods, four levels or terraces have been formed around Hamoom lake and are regarded as important relieves of Sistan Plain [15]. Sandy dunes have been expanded in northeast of Zabol and along Maleki and Niatik River with approximate area of 300 hectares. Sand dunes of Sistan are mobile and their movement to the surrounding villages led to evacuation of some villages by the people. Yardang relief has been observed in margin of Hamoon pits day winds blowing in Sistan in surface of loose sediments of clay pans must be responsible for this relief [Fig2]. Fig 2- expansion of sandy dunes (Barkhan) in farmlands of Jazink-Ghale No region III. Agricultural drought in the region Need of plan for water depends on dominant atmospheric conditions, biological characteristics of special plant, its growth stage and physical and biological characteristics of soil. Good definition of agricultural drought should include variable sensitivity of the plants during plan growth from sprouting to ripeness. Lack of ISSN: ISBN:

3 humidity in upper layers of soil can delay sprouting during cultivation leading to decrease of shrub density in hectare and defective final yield [Fig 3]. however, in case that humidity of upper soil (ground level) is sufficient for needs of primary stages of growth, humidity deficiencies in lower layers of soil will not have considerable effect on final yield of the plant[16],[ Fig 3]. IV. Hydrological drought in the region: In Sistan region, hydrological drought results from dam building activities in upstream of Hirmand watershed basin in Afghanistan and non observance of Iran water right. All of these factors in the region caused some changes in uses. Conversion of susceptible farmlands to deserted lands, destruction of pastures, dryness of basins etc led to another drought called socioeconomic drought in the region. Unemployment, poverty, false jobs and trafficking are of its signs [3]. Fig 3. farmland deserted due to drought V. Effects of drought on erosion and creation of storm In order to study relationship between drought and wind erosion periods in the region, some of the characteristics of wind erosion relating to drought were studied with use of storms tracking using images such as MODIS from TERAA and ETM+ from Land sat in addition to study of wind components such as dominant wind, average rate of wind etc as shown in the following table. Procedure in this stage includes preprocessing of images m processing of images, mixing information layers with images, interpretation of images in order to recognize regions in which dust storms are surveyed and the way in which their particles are diffused and presentation of the results[fig4]. Fig 4. Dryness of plains due to drought (Land sat 2001 and 1996). Table 1- specifications of MODIS from TERAA No Type of data Date 1 MODIS May MODIS Jun MODIS Jun MODIS Jul Table 2- specifications of ETM+ from Land sat 1 ETM ETM ETM /10/2 Land sat 2000/07/01 Land sat 2000/04/12 Land sat The images obtained from space have some geometrical errors. For solving this problem, field checks and drafts of Global Position Systems (GPS) were done with use of topographic maps 1: and root mean square error was calculated and the problem was solved. After correction of geometrical errors, single band spectral representation methods such as contrast expansion in linear way and representation in histogram adjustment way were used. With increase in quality of bands in the above ways, parameters of correlation between bands were calculated and suitable false color composite (FCC) was introduced [15]. Information layers were combined with images for expressing images of information layers such as zones of plains, urban and rural centers, channel etc after being digitalized in GIS medium. Fig 5. mixing different layers with Land sat images Iv. Images interpretation in order to recognize effects of dust storms and the way in which their particles are diffused during drought In this stage, field checks and visual and digital interpretation of some problems such as direction of storms, extension of storms in Iran and the neighboring countries as well as their diffusion were studied. Visual interpretation of MODIS images shows that this lake is regarded as one of the major places of draft and centers of storms due to drought of plains especially Sabopri Plain and Poozak and Hirmand plains are important after this plain. Farmlands deserted due to drought are of the other regions susceptible to wind erosion. Studies show that farmlands subject to draft and transfer of wind sediments in the region include farmlands with dune, farmlands with deflation farmlands with low wind erosion which have total area of 1572 sq km. ISSN: ISBN:

4 Studies and measurements done on surface of storms and at time of drought show that (figures 2 to 6) intensity of the storms is different from each other and area difference in different events is quadruple. In all of the studied storms, surface covered by dust relating to Iran (Sistan region) and Afghanistan shows low changes in comparison to with changes in total area of storms because origin of these storms is in these two countries and storm reaches Pakistan only in severe storms [15]. County Zabol Affected region Draft region surfaces (hectare ) H M L total Miankangi Jezink Rig Chah and Tasooki Total Table 4- surfaces of regions under wind erosion on the basis of regions of sedimentation in Sistan region (Zabol) Affected region Sedimentation region surfaces (hectare) Total sum Total sum County T1 T2 total S1 S2 S3 Total Figures4: MODIS image relating to storm of 2 June 2001 Mianka ngi Jezink Zabol Rig Chah and Tasooki Total Figures 5: MODIS image relating to storm of 4 July 2001 Figure 6- MODIS images relating to storm of august 2002 VII. Surfaces of regions affected by wind eosin in the studied region In Zabol region, three regions are affected by wind erosion and in some regions, wind erosion and draft and deposit are out of Afghanistan. In table 4, surfaces of high draft region H, medium draft erosion, M and low draft region L, surfaces of transport region with high intensity T1, surfaces of transport region with intensity of T2 and surfaces of active sedimentation region S1, semi active sedimentation region S2 and inactive sedimentation region S3 and total volume of draft, transport and sedimentation surfaces has been specified. Table 3- surfaces of regions under wind erosion on the basis of regions of draft, transport and sedimentation in Sistan region (Zabol) Conclusion: Sistan region centralized in Zabol County is one of the critical foci of wind erosion. One of the main characteristics of this plain is dust and sand storms. Due to consecutive droughts and blockage of Kajaki dam water leading to dryness of plains and river bed of Hirmand, intensity of storms have increased. This caused many farmlands and susceptible lands to be subjected to deflation and transfer of the soil surface separates or burial of these separates under sands due to movement of drifting sand. Speed of wind starts in the region since May and is maximized in July and August and it is reduced gradually. The highest values relate to June, July and August which are 11.49, 13.1 and respectively. In Zabol region and in all seasons of statistical period, there are erosive winds and their difference is in rate and power of erosion. May, June, July and August with values of 20.90, 2.13, and have the highest values of wind speed. Most damages result from wind erosion and creation of wind erosion faces resulting from direction and speed of dominant wind in the region. Wind speed starts in May and is maximized in July and August and is reduced gradually afterward. Maximum values are between 9 and 14.7 m/s for the above months. Speed and direction of dominant wind in Zabol station are northwest with 15.5% and north with 42.4% during the studied years. In Zabol region, there are three regions under wind erosion and some regions of wind erosion and draft and sedimentation are out of border of Afghanistan. In addition to wind speed, direction and domination of wind are effective on wind sweeping. On the basis of the available statistics, average rates of erosion in the studied period are.7, 10,.9, 11.1, 11.3, 12.4, 11.9, 11.1 and 11.6 respectively. References: ISSN: ISBN:

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