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Investigating effect of land use optimization on erosion and sediment yield limitation by using of GIS (case study: Ilam dam watershed).


Regarding the importance of the water resources in Iran, it is required to take more attention to the bodies of sweet water, as the dams. One of the most important methods in keeping such water resources is the correct management for decreasing erosion and produced sediment whoese requisite is being aware of the amount of sedimentation in the upper basin of the dams. The soil type and the its erosion in a region depend on various factors as climate, ups and downs, soil type, and land usage. In such a situation, the land usage, because of the influential role of humanbeing in that case, is much more important than the other factors. In other words, the kind of land utilization is regarded as an important factor in erosion and sediment production in the aquifer basins (Casas, 1983). In Iran, because of disregarding the issues of incapability and improportionality of land usage, the lands are mostly used inappropriately, and it would lead to erosion and sediment of the aquifer basins. There are many studies on verifying the changes of land usage and its influences on erosion and sedimentary. Cheppi [3] in a study on the basin of Gheshlagh Sanandaj dam showed that the farming lands of the basin including 8.34 per cent of the whole basin, had inappropriate usage and were not coincident with the basin's potentialities, and the erosion and sediment of the aquifer basin would decrease to 35 per cent if the poor and destroyed pastures were revived and the farming lands changed to pastures. Ghaffari [9] studied the aquifer basin of the Ala river in Marv Dasht and declaired that the extra shifts of pastures and woodlands to farming lands and the other illegal uses resulted in an increase in erosion and sediment production to 15 per cent. Nabi Pei Lashkarian [17] studied the effects of changes in land usage on soil erosion and sedimentary in the aquifer basin of Masouleh, Gilan. Using the models MPSIAC and EPM, he compared the sedimentation of the basin in the present and future conditions of land usage (according to the land potentiality). The results of these two models showed that by amending and reviving the vegetation and utilizing the lands based on the soil potentiality, the special erosion would decrease in MPSIAC model to 9.23 per cent and in EPM model to 22.98 per cent. He also suggested that the erosion intensity in dry farming agriculture is much more than the rest. Dehdar Dargahi and Makhdoum [5] got involved in testing Arasbaran forest basins. Identifying the ecologic, economic, and social resources, providing the related maps and analyzing the data in a systematic way, preparing the environmental units and using the special ecologic models, they determined the region power for Faryaab land use, foresting, pasturing, dry farming, protective forestry, extensive and concentrated tourism, and protection respectively as 5.38, 1.32, 17.43, 15.17, 2.13, 28.47, 0.01, 30.09. Fathollahi [7] in a study on improper use of land in various years and its influence on the range of sedimentation, their phisical characteristics and erossiveness in Bazaft aquifer basin in Chaharmahal Bakhtyari province showed that the changes in land usage in the field of natural resources as jungle, and treed pasture, to other land use where agriculturing plays the main role, leads the soil to low quality and brings sensitivity against erosion in the top soil. Mahfouzi et al [12] using GIS, dealt with surveying Dadghan aquifer basin in Tafresh and determined the proprtion of lands to various land use and presented the management strategies in that field.

Tajvani [22] examined the influences of land usage on erosion in various slopes in different regions of India and came to this conclusion that the natural vegetation and natural grasses in comparison with the planted lands with weath, barley, and corn involve less loss. Morgan [16] according to a study on the soil erosion in England, found out the utilization of the farming lands has an important control over the source and amount of sedimentary in river. He also concluded that changing the pasturelands to farming lands causes a huge erosion and the land usage has an important control over the source and amount of sedimentary in the river. Tavan (1998) studied the influence of land usage over wasted water coefficient and producing sediment in four small basins in Taiwan and came to this conclusion that increasing the degree of land utilization in every land unit brought an increase in the impure wasted water coefficient and pick wasted water coefficient and sediment production. All these coefficients would decrease if the soil was protected by vegetation. He also proved that when the natural or artificial vegetation are used for soil protection, the amount of sedimentary would decrease to a meaningful range. Maul et al [15] did a study in Kazakhstan and suggested that changing the pasturelands to farming and ploughed lands would result in a severe decrease in soil fertility, especially in its Hummus. Venyampi et al [24] in Belgium suggested that the minor changes in land use of the jungles to farming lands had a meaningful influence on increasing the soil erosion. Olga Tezortecava [20] in her graduate dessertation on the dinamic servey of the influences of time and place of the land usage on the aquifer basin of the Black Stone river in the U.S and other 115 sub basins in GIS environment and using SWAT model showed that the changes in land usage had short term and long term influences over water resources, environment, and human communities. She considered the land usage changes and evaluating the erosion and sediment in the aquifer basins as a gaurantee for qualifying standards of water in the course of decreasing the erosion and sediment in the basin. Demir,Yasin Kaya et al (2008) in a study on the stable evaluation of the land usage in Irmander valley in the northeast of Turkey (Trabouzan province), concluded that developing the rural and urban areas in the aquifer basin of the studied river, because of crowd loadings and the industrial developments, requires determination of the optimal land usage. They found out that a large number of the constructing activities are against the stable and basic plans. At the end, they suggested a few codified plans for reviving the region to be accomplished with the legal requisites and substitutionary policies. The objectives of the present study are: determining the erosion and sediment of various types in land land use using the exprimental model EPM, preparing the existed and optimal land usage maps of the studied basin, preparing the existed and optimal erosion and sedimentary maps and suggesting the proper utilization of the lands for decreasing the erosion and sediment.

Materials and Methods

The position of the studied region:

The aquifer basin of Ilamdam in the east of Ilam county, and regarding the political divisions is in the confinement of Ilam and Mehran counties, and its geographical specialities are 46[degrees] 20' 30" to 46[degrees] 39' 33" eastern longitude and 33[degrees] 23' 32" to 33[degrees] 38' 51" northern longitude. The basin area is 46822 hectares (fig. 1). The minimum hight of the studied region in the southern and the outer part of the basin is 640 m and its maximum hight in Ghalarang mount located in the north of the basin is 2590 m. Climatically the region is semi arid (Mediteranian climate) with the avarage annual rainfall of 592.78 mil. The most important river in the basin is Kanjancham which is composed of two rivers, Chaviz and Gol Gol, and Ilam dam is established at Kanjancham river surrounding. The geological basin of the studied area involves Pabede, Sourak, Sourge, Imam Hasan, Gachsaran, Gourpi, Asmari, Ilam, and Abroft. The avarage slope of the basin is 30 per cent, and different types of erosion including superficial, ploughed, aqueducting, and moated are observed there. The aquifer basin of Ilam dam is divided into six sub basins [A.sub.1], [A.sub.2], [A.sub.3], [A.sub.4], [A.sub.5], and [A.sub.6], based on major branches, density of the aqueduct, and the extent of the limits [18].



In order to prepare the erosion plan and to evaluate the produced sediment in the aquifer basin of Ilam dam the required basic maps are prepared. These maps include the geological map, the erision types map, and the land use map, and the land slope map was obtained from DEM (Figs. 2, 3, 4, 5).





In order to study the sedimentation of the basin using EPM model, the influential factors in sedimentation of the EPM model involving the erosion coefficient, earth using coefficient, sensitivity coefficient of soil and stone, the average slope, and the sedimentation coefficient of the sub basins were evaluated and the arranged distinctions and the sediment production of the sub basins were estimated using the following formula [8].

[G.sub.sp] = [W.sub.sp] x Ru (1)

In this ratio:

Gsp = sediment production, cubic meters of the square miles annually

Wsp = special erosion, cubic meters of the square miles annually

Ru = sedimentation coefficient of the basin which is obtained from the following ratio:

Ru = 4 x[(O x D).sup.1/2][L + 10)] (2)

In this ratio:

O = basin environment, sm

L = aquifer basin longitude, sm

D = hight difference between the avarage hight and

the outer point hight of the basin, km

Wsp is calculated out of the following ratio:

[W.sub.sp] = T.H.[Z.sup.2/3] [pi](3)


H = the avarage annual rainfall, mil

Z = erosion coefficient achieved out of the following ratio:

Z = Y.Xa{[psi]/ + [I.sup.1/2]) (4)

Where Y, Xa, and [psi] are respectively the sensitivity agent of soil and stone, earth using agent, and erosion agent which are devoted to each sub basin based on the tables related to each model.

I = earth slope agent, per cent

[pi] = 3.14

T = temprature coefficient calculated out of the following ratio:

T = [(t/10 + 0.1).sup.1/2] (5)

Where t is the avarage annual temprature according to [degrees]C. The sediment quantity of the basin was obtained according to ton per year using the special sediment concerning the specific body of the basin sediments. For comparing the evaluated sediment by the exprimental model of the sedimentary station in the outer part of the basin, the suspended load and bed load were used. The suspended load was calculated as the annually avarage statistical period and the bed load was calculated through using its common relations with suspended load and was determined for all the aquifer basin of Ilam. The avarage annual sediment of the studied basin was evaluated by the EPM exprimental model. Then the numbers obtained from the sedimentary station and the exprimental model were compared and tested (unisample t-test) in SPSS, and the adaptability of the numbers related to the model with the sediment quantity of the sedimentary station came into consideration. Then, the studied basin was evaluated systematically [14] and tested quantitatively [14] and the proper land use related to the region power was determined. The new achieved map was entered to EPM model for the second time and the region erosion map and the annual sediment was calculated again.


The results of utilizing EPM model for the present land use of the basin and the calculated parameters for sub basins and the whole basin are placed in Table (1). Fig (6) shows the achieved erosion map for the present land use. Calculating the general sedimentation of the station and comparing it with the results of the model showed that they had a meaningful difference in 99 per cent of thr cases and this suggests the accuracy of the model usage for the region (Table 2).

For studying the optimal use of the lands in decreasing the erosion and sediment in the aquifer basin of Ilam dam, the systematic evaluation method [14] and the quantitative testing [14] were used and the proper land use related to the productive power of the region was determined (Fig. 7). Then, placing the new map in the model and recalculating the erosion and sedimentary quantity of the studied basin, the following results shown in Table (3) were achieved and Fig. 8 shows the erosion map of the future land use.





Results and Discussion

The present study deals with land optimalization in the aquifer basin of Ilam dam for achieving the soil erosion and the sediment minimalization which would result in the stable usage of water and soil resources. For achieving the appropriate transmittal of the land use according to the standard conditions and achieving the regarded objectives concerning the standards of different land use and performing the existing confinements in the region, the systemic method [14] was suggested and performed for the optimal solvation of the problem in the aquifer basin of Ilam dam. Evaluating the estimated sediment through the EPM exprimental model and comparing it with the estimated annual sediment of the outer station of the basin through the statistical test clarified the reliability of the model carefulness. The results achieved by Dadkhah and Najafinejad [4] in the aquifer basin of Latian dam and by Pishdad Soleiman Abad et al., [21] in the aquifer basin of Cheragh Veis in Saghez county affirm these results. In this study, the results of sediment evaluation and debi statistics were analyzed and compared with the derived results of studying the aforementioned model. The genera produced sediment of the basin was estimated as 16.58 ton/hectars annually through a true statistical analysis [1,2] which has an intimacy with the general produced sediment of the basin in EPM model which is 18.81 ton/hectars annually. Therefore, this model is presently efficient for the studied basin. The results show that the produced sediment with the present land use for the whole basin is annually 880871ton from which the sub basin A1 possesses the most special annual erosion and the sub basin A2 has the least special annual erosion. Generally speaking, regarding the resulted sediment from the model for the whole basin, we can come to this conclusion that because of the high sensitivity of the composing structures to erosion, weak and destroyed vegetation, developing types of erosion involving the superficial, ploughed, aqueducting, and moated,and also lack of balance between the region power and its present usage in some areas, the erosiveness of the studied region is considerablly high. The results of the present study have similarity with those achieved by Jahanseir [10,21]. After determining the optimal land use of the aquifer basin of Ilam dam, the suggested testing map was entered to the EPM model for reevaluation. The results show that accomplishing the testing map decreases the produced sediment of the studied basin to 401276 ton per year (around 54%). This shows the importance of proper use of the lands. Therefore, the results affirm the far distance of the present situation with the optimality for achieving the minimum erosion and managing the proper measuers to change or amend the present land use. The results by Mahmoudzadeh [13] on Sydney, Australia, Ghafari [9] on the aquifer of the Ala river, Marvdasht, Niknami (2002) on Siahroud, Morgan (1998) on England, and Niampi et al., (2002) and Pishdad Soleimanabad et al [21] on the aquifer basin of Cheragh Veis verify the present results.


[1.] Aazami, Aiad, 2001. Determination the suitable method for estimate suspended sediment load In Ilam dam watershed. MS.c thesis, Agriculture and Natural resources Sciences University, pp: 83.

[2.] Askari, S. and M.R. Jafari, 2008. Estimating soil erosion and sediment Yield in Ilam Dam watershed using MPSIAC. Geographic Research Journal, 64: 29-3.

[3.] Chepi, Kamran, 1998. Investigating type and amount of erosion in relation to managing utilization of land use and determing sediment yield ratio in order to land use optimization .M.Sc thesis. Natural Resources College, Tarbiat Madares University.

[4.] Dadkhah, M. and A. Najafi Nejad, 1997. Efficiency of EPM model to estimate sediment and erosion in Latyan Watershed, Iran, Natural Resources Science Magazine., 50(1): 76-85.

[5.] Dehdar, Dargahi and M. Makhdoom, 2000. Land evaluation of Arasbarian forests. Journal of Environmental science. Winter. (26): 25-34.

[6.] Demir, Y.M., M. Atasoy, T. Bayrak and C. Biyik, 2008. Evaluating Sustainable Land Use for the De Irmendere Valley: A Case Study From Northeastern Turkey.

[7.] Fatholahi, H., 2000. Inappropriate use of lands in different years and its effect on sediment yield rate, their physical properties and erodibility in bazft watershed in Chaharmahal Bakhtiari province, M.Sc thesis, college of Agriculture, Isfahan University of Technology.

[8.] Gavrilovic, Z., 1988. The use of an empirical method(erosion potential method) for culculating sediment production and transportation in unstudied or torrential streams. Proceeding of International Conference on River Regime, England. 18-20 May.

[9.] Ghafary, Alireza, 1998. The effects of land use on river erosion of the Marv Dasht. Art collection and scientific seminar lectures to study methods of the optimum land use, Tehran, watershed management branch, Jihad Sazandegi Ministry, pp: 324-344.

[10.] Jahanseir, R., 2001. A study of the effects of soil erosion hazard(FAO model) on the amount of soil erosion using GIS. M.Sc thesis of Grogan university of Agricultural Sciences and Natural Resources., pp: 113.

[11.] Kassas, M., 1983. The Global biosphere: Conservation for survival. Mazingira., 7(2): 2-13.

[12.] Mahfouzh, M., A. Dervish sefat and M. Makhdoom, 2001. Land use planning of Dadqan Tafresh watershed using GIS, Journal of Environmental Science, 27(27): 108-99.

[13.] Mahmoudzadeh, A., 1994. A study on the relationship between sediment generation and land use. Forest and Range Magazine., 36: 25-30.

[14.] Makhdom, M., 2005. Land evaluation. Sixth edition, Teran University publication.

[15.] Maul, Y., V. Garmalov and J.S. Rikoon, 1993. Soil Conservation and Agriculture Land Use Issues in Kazakhstan. Journal of Soil and Water Consevatin., 48(5): 370-375.

[16.] Morgan, R.P.C., 1980. Soil erosion and conservation in Britain. Progress in Physical Geography. 4:24-47

[17.] Nabipey Lashkaryan, S. 2000. A study on the effect of land use on soil erosion and sediment production in Masooleh Watershed, Guilan. M.Sc thesis of Gorgan University of Agricultural Sciences and Natural Resources., pp: 121.

[18.] Nepta Advisory Coopeation, 2001. Detail project of Ilam Dam watershed, Jahad and Agriculture Organization of Ilam province., pp: 135.

[19.] Niknami, D., 2000. Optimizing and Management of soil erosion in Damavand Watershed, Research and Construction Magazine., 54: 82-88.

[20.] Olga Tsvetkova, A., 2007. Spatial and Temporal Dynamics of Land Use Impacts on Water Quality in Watershed Systems, Novgorod State University, Russia, M.Sc thesis, University of Massachusetts Amherst Pishdad Soleimananabad, L., A. Najafi Nejhad, A.S. Mahiny and H. Khaledian, 2008. A study on the effects of changing land use on soil erosion in Cheragh veis watershed using geographic information systems (GIS). Journal of Agricultural Sciences and Natural Resources.,15(1).

[21.] Tejwani, K.G., 1980. Soil and Conservation In: Handbook of Agricalture, Indian council of Agriculture Research, New Delhi.

[22.] Tuan, C.H., 1989. Runoff Coefficient and Sediment Yield in Small Watershed under Land Use Changes in Taiwan. Proceeding of the International Conference on Channel Flow and Catchments Runoff. Uni.of.Virginia. Charlotteville VA. pp: 121 129.

[23.] Venyampe, A.J., G. Govers and C. Puttemans, 2002. Modeling Land Use changes and their impact on soil erosion and sediment supply to rivers. Journal of Earth Surface Processes and Landforms., 27: 481-494.

(1) Ghobad Rostamizad, (2) Zahra Khanbabaei

(1) Ph.D. student of Watershed Management, Faculty of Natural Resources, Univ. of Tehran, Karaj, Iran

(2) Former Msc. Student of Geomorphology, Tarbiat Moallem university of Tehran

Corresponding Author

Ghobad Rostamizad Ph.D. student of Watershed Management, Faculty of Natural Resources, Univ. of Tehran, Karaj, Iran

E-mail:; Tel: 09189409568
Table 1: The erosion coefficient, the avarage annual erosion,
sedimantation coefficient, specified sediment in the sub
basin area and the whole basin in the present usage

sub basin         Area           Z       [Z.sup.1/5]   Wsp
                  ([km.sup.2])                         (m3/km2/

[A.sub.1]         132.88         1.031   1.04          2540.34
[A.sub.2]         85.96          0.73    0.63          1523.93
[A.sub.3]         68.86          0.77    0.68          1643.85
[A.sub.4]         41.99          0.76    0.66          1600.87
[A.sub.5]         70.31          0.75    0.65          1574.71
[A.sub.6]         68.21          0.79    0.70          1698.28
The wole basin

sub basin         Ru     Gsp        Gsp
                         (m3/km2/   (ton/year)

[A.sub.1]         0.91   2319.64    400715.88
[A.sub.2]         0.29   435.82     48703.35
[A.sub.3]         0.85   1400.54    125377.72
[A.sub.4]         0.68   1084.19    59184.18
[A.sub.5]         0.81   1277.60    116778.69
[A.sub.6]         0.86   1467.36    130112.13
The wole basin

Table 2: The suspended load and the bed load

the avarage suspended load during the    6323361.2
statistical period (tons per year)

the avarage bed load during the          158090.3
statistical period (tons per year)

the total sedimentary load               790451.5
(tons per year)

790451.5/47675 = 16.58 tons per hectares

Table 3: The erosion coefficient, the avarage annual erosion,
the sedimentation coefficient, the specified sediment in the
sub basin and the whole basin in the future land use

sub basin          Area           Z      [Z.sup.1/5]   Wsp
                   ([km.sup.2])                        (m3/km2/

[A.sub.1]          132.88         0.82   0.74          1812.87
[A.sub.2]          85.96          0.59   0.45          1096.13
[A.sub.3]          68.86          0.44   0.29          699.58
[A.sub.4]          41.99          0.40   0.25          619.82
[A.sub.5]          70.31          0.40   0.25          605.56
[A.sub.6]          68.21          0.34   0.20          488.42
The wole basin     468.22         0.49   0.34          838.64

sub basin          Ru     Gsp        Gsp
                          (m3/km2/   (ton/year)

[A.sub.1]          0.91   1655.38    285964.16
[A.sub.2]          0.29   313.48     35031.45
[A.sub.3]          0.85   596.03     53357.47
[A.sub.4]          0.68   419.78     22914.87
[A.sub.5]          0.81   491.30     44907.41
[A.sub.6]          0.86   422.01     37419.90
The wole basin     0.93   783.16     479595.26
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Title Annotation:Original Article
Author:Rostamizad, Ghobad; Khanbabaei, Zahra
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:May 1, 2012
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