**17. Results of field and laboratory analyses**

Table 4 shows the mean and variation coefficient of all measured variables including physical and chemical properties of the samples and variables measured in the field. The amount of electrical conductivity is usually bellow 3 ms/cm, the abundance of silt-size particles is more than %55 is completely evident and in some samples reaches %70. In contrast, abundance of clay particles is not more than %30 and the mean amount of sand in all samples is less than %20. Gypsum is not present in many samples or is little. Carbonate anion is not present.

Investigation of Effective Factors on Runoff Generation and

Sediment Yield of Loess Deposits Using Rainfall Simulator 139

Total runoff volume cc 69 1653.61 39.92 Turbidity gr/lit 69 17.51 61.73 gr/m 69 32.36 85.83 Plot sediment 2 Slope % 69 19.46 49.27 Land cover % 69 23.19 26.40 A-horizon depth cm 69 19.83 46.07 Humidity % 69 6.48 23.27 gr/cm 69 1.34 4.41 Bulk density 3 EC ms/cm 69 2.20 17.99 pH 69 7.93 1.68 Organic mater % 69 1.54 19.62 CaSO4 meq/100s 69 0.78 121.05 Sand % 69 19.36 22.55 Clay % 69 28.88 13.55 Silt % 69 51.75 8.91 CEC cmol/kg 69 17.16 12.16

equivalent calcium carbonate % 69 14.48 17.68

Mixed layer Clay Minerals % 69 2.61 159.62

Table 4. Descriptive statistics of all measured variables

Ca meq/lit 69 15.28 18.37 ++ Mg meq/lit 69 12.80 31.36 ++ K meq/lit 69 0.36 52.07 + Na meq/lit 69 26.11 46.97 + Sum of cations meq/lit 69 54.55 25.38 CO meq/lit 69 0.00 - 3-- HCO meq/lit 69 3.42 19.20 3- SO meq/lit 69 35.66 39.29 4-- Cl meq/lit 69 15.39 46.08 - Anion sum meq/lit 69 54.48 28.71 SAR 69 7.00 46.13 ESP 69 8.14 48.60 Illite % 69 31.30 13.60 Chlorite % 69 25.43 16.43 Kaolinite % 69 19.35 19.27 Smectite % 69 22.17 17.50

variation (%) Variable Unit N Mean

Coefficient of

Fig. 10. Land units map of the studied area

Fig. 11. Map showing the location of rainfall simulator analyses

Fig. 10. Land units map of the studied area

Fig. 11. Map showing the location of rainfall simulator analyses


Table 4. Descriptive statistics of all measured variables

Investigation of Effective Factors on Runoff Generation and

**type** 

erosion 0-10

erosion 10-20

erosion 20-30

**work unit Geology Erosion** 

**R-RE-2** Loess Rill erosion 10-20

**R-RE-3** Loess Rill erosion 20-30

**R-RE-4** Loess Rill erosion 30-40

**R-SE-1** Loess Sheet

**R-SE-2** Loess Sheet

**R-SE-3** Loess Sheet

**R-SRE-1** Loess Sheet & rill 0-10

**R-SRE-2** Loess Sheet & rill 10-20

**R-SRE-3** Loess Sheet & rill 20-30

**R-SRE-4** Loess Sheet & rill 30-40

**4SD** Loess Sheet & rill 30-40

Table 6. Data from work unit in rangeland landuse

**R-SRE-**

Sediment Yield of Loess Deposits Using Rainfall Simulator 141

reaching arid climate, Smectite increases. Tables 5 and 6 show runoff volume, sediment concentration and sediment production of each plot in 3 repetitions in each land unit. Table

7 shows the average runoff and sediment in dry-farming and range Landuse.

**Slope treatme**

**nt** 

**Sample no.** 

**% cm3 gr/lit gr/m2** 

1 37 1,160 8.65 10.03 2 38 1,420 7.23 10.27 3 39 1,310 10.24 13.41

1 40 1,670 16.63 27.77 2 41 1,750 12.80 22.40 3 42 1,550 15.62 24.21

1 43 2,140 21.02 44.98 2 44 2,280 22.63 51.60 3 45 2,420 16.57 40.10

1 46 1,469 2.45 3.60 2 47 1,120 3.16 3.54 3 48 1,000 2.25 2.25

1 49 2,220 6.44 14.30 2 50 1,820 5.61 10.21 3 51 1,600 8.39 13.42

1 52 2,530 12.80 32.38 2 53 1,750 11.53 20.18 3 54 2,180 10.41 22.69

1 55 970 3.15 3.06 2 56 740 5.20 3.85 3 57 1,050 3.90 4.10

1 58 1,930 10.56 20.38 2 59 2,340 14.75 34.52 3 60 1,870 8.81 16.47

1 61 2,010 16.03 32.22 2 62 2,340 18.10 42.35 3 63 2,090 17.18 35.91

1 64 2,740 16.34 44.77 2 65 2,420 19.70 47.67 3 66 2,980 14.55 43.36

1 67 2,550 16.82 42.89 2 68 2,280 21.25 48.45 3 69 2,420 22.52 54.50

**Runoff Turbi-**

**dity** 

**Plot sediment** 


Table 5. Data from work unit in Agriculture landuse

Clay minerals of loesses are smectite (18 A° peak in MGG), illite (10 A° peak), kaolinite (considerable decrease of 7.1 A° peak in KT relative to other treatments) and chlorite (14 A° peak in all treatments). Clay minerals in the order of decreasing amount are as follows: Illite, Chlorite, Smectite, Kaolinite and low amount of Mixed-layered clay minerals. In areas

**Slope treatment Sample** 

**no.** 

**% cm3 gr/lit gr/m2** 

1 1 570 10.44 5.95 2 2 800 9.52 7.62 3 3 710 12.12 8.61

1 4 590 12.95 7.64 2 5 410 7.88 3.23 3 6 510 10.25 5.23

1 7 1,060 21.07 22.33 2 8 1,320 15.96 21.07 3 9 1,620 17.33 28.07

1 10 1,790 37.23 66.64 2 11 1,970 28.41 55.97 3 12 2,330 23.78 55.41

1 13 2,470 38.83 95.91 2 14 2,850 35.63 101.55 3 15 2,700 28.39 76.65

1 16 1,040 12.18 12.67 2 17 1,160 11.23 13.03 3 18 970 9.75 9.46

1 19 1,380 19.12 26.39 2 20 1,500 13.96 20.94 3 21 1,190 15.15 18.03

1 22 820 11.31 9.27 2 23 570 9.87 5.63 3 24 750 13.56 10.17

1 25 940 23.96 22.52 2 26 1,400 25.44 35.62 3 27 1,500 19.22 28.83

1 28 1,550 26.82 41.57 2 29 1,710 20.47 35.00 3 30 1,410 21.24 29.95

1 31 1,910 36.74 70.17 2 32 1,410 34.10 48.08 3 33 2,100 27.72 58.21

1 34 2,200 50.85 111.87 2 35 2,370 47.50 112.58 3 36 2,400 45.56 109.34

**Runoff Turbi-**

**dity** 

**Plot sediment** 

**work unit Geo-**

**logy** 

**A-RE-1** Loess Rill erosion 0-10

**A-RE-1SD** Loess Rill erosion 0-10

**A-RE-2** Loess Rill erosion 10-20

**A-RE-3** Loess Rill erosion 20-30

**A-RE-4** Loess Rill erosion 30-40

**A-SRE-1** Loess Sheet & rill 0-10

**A-SRE-2** Loess Sheet & rill 10-20

**A-SRE-2G** Loess Sheet & rill 10-20

**A-SRE-3** Loess Sheet & rill 20-30

**A-SRE-** Loess Sheet & rill 30-40

Table 5. Data from work unit in Agriculture landuse

Clay minerals of loesses are smectite (18 A° peak in MGG), illite (10 A° peak), kaolinite (considerable decrease of 7.1 A° peak in KT relative to other treatments) and chlorite (14 A° peak in all treatments). Clay minerals in the order of decreasing amount are as follows: Illite, Chlorite, Smectite, Kaolinite and low amount of Mixed-layered clay minerals. In areas

erosion 0-10

erosion 10-20

**A-SE-1** Loess Sheet

**A-SE-2** Loess Sheet

**Erosion type** 

> **work unit Geology Erosion type Slope treatme nt Sample no. Runoff Turbidity Plot sediment % cm3 gr/lit gr/m2 R-RE-2** Loess Rill erosion 10-20 1 37 1,160 8.65 10.03 2 38 1,420 7.23 10.27 3 39 1,310 10.24 13.41 **R-RE-3** Loess Rill erosion 20-30 1 40 1,670 16.63 27.77 2 41 1,750 12.80 22.40 3 42 1,550 15.62 24.21 **R-RE-4** Loess Rill erosion 30-40 1 43 2,140 21.02 44.98 2 44 2,280 22.63 51.60 3 45 2,420 16.57 40.10 **R-SE-1** Loess Sheet erosion 0-10 1 46 1,469 2.45 3.60 2 47 1,120 3.16 3.54 3 48 1,000 2.25 2.25 **R-SE-2** Loess Sheet erosion 10-20 1 49 2,220 6.44 14.30 2 50 1,820 5.61 10.21 3 51 1,600 8.39 13.42 **R-SE-3** Loess Sheet erosion 20-30 1 52 2,530 12.80 32.38 2 53 1,750 11.53 20.18 3 54 2,180 10.41 22.69 **R-SRE-1** Loess Sheet & rill 0-10 1 55 970 3.15 3.06 2 56 740 5.20 3.85 3 57 1,050 3.90 4.10 **R-SRE-2** Loess Sheet & rill 10-20 1 58 1,930 10.56 20.38 2 59 2,340 14.75 34.52 3 60 1,870 8.81 16.47 **R-SRE-3** Loess Sheet & rill 20-30 1 61 2,010 16.03 32.22 2 62 2,340 18.10 42.35 3 63 2,090 17.18 35.91 **R-SRE-4** Loess Sheet & rill 30-40 1 64 2,740 16.34 44.77 2 65 2,420 19.70 47.67 3 66 2,980 14.55 43.36 **R-SRE-4SD** Loess Sheet & rill 30-40 1 67 2,550 16.82 42.89 2 68 2,280 21.25 48.45

3 69 2,420 22.52 54.50

reaching arid climate, Smectite increases. Tables 5 and 6 show runoff volume, sediment concentration and sediment production of each plot in 3 repetitions in each land unit. Table 7 shows the average runoff and sediment in dry-farming and range Landuse.

Table 6. Data from work unit in rangeland landuse

Investigation of Effective Factors on Runoff Generation and

Sediment Yield of Loess Deposits Using Rainfall Simulator 143

Fig. 12. Mean sediment concentration and sediment production in rangeland and

show mean amount of runoff and sediment in different slope classes, respectively.

In ANOVA Test, due to the fact that the level of significant is lower than 0.01, there are significant differences in runoff and sediment production between different slope classes. For determining which slope classes are different from each other, Clustering of Mean Method was used. The results of Duncan Method indicates the notable effect of slope on the amount of runoff and sediment production, so that each slope class is clustered in a separate group and is indicative of meaningful difference between slope classes. Figure 13 and 14

dry-farming cultivation


Table 7. Average runoff and sediment in dry-farming and range landuses
