ACTUAL EROSION RATE MEASUREMENT AND SOIL LOSSES DEPTH AT COBAN RONDO SUB-WATERSHED, MALANG REGENCY OF INDONESA

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1 J. Baic. Appl. Sci. Re., 2(1) , , TextRoad Publication ISSN Journal of Baic and Applied Scientific Reearch ACTUAL EROSION RATE MEASUREMENT AND SOIL LOSSES DEPTH AT COBAN RONDO SUB-WATERSHED, MALANG REGENCY OF INDONESA Liliya Dewi Suanawati, Bambang Suharto* Faculty of Agriclutural Technology, Univerity of Brawijaya, Malang, Indoneia ABSTRACT Thi paper tudied the meaurement of actual eroion rate and the depth of oil loe. Location of tudy wa at Coban Rondo Sub-Waterhed, Malang Regency of Indoneia. The methodology conited of decriptive analyi and field experiment. Reult wa ued to know actual eroion rate at Coban Rondo ub-waterhed and any kind of land ue. In addition, it wa intended to know the depth of oil loe at the location. KEY WORDS: actual eroion rate, depth of oil loe. INTRODUCTION Great attention to the procee of deertification in many river becaue of their flow regulation wa given in the lat decade. Degradation of oil and vegetation cover, increae in mineralization of river water, had been explored [1]. Drying and deertification procee of delta landcape in pace and time in the firt decade wa differentiated after creation of reervoir and it depended on the feature of water regime in natural condition. Area of river mouth wa a pecific phyiographic abject. It wa covering the area of river outflow into a water body. The mouth area generally conited of the part of the lower mouth, including the delta and the part of near hore area of the water body [2]. A many other cae of mouth, thi wa an area with pecific characteritic. It wa often a zonal landcape, traditional hydrological regime and radical change in the phyical like edimentation and eroion, chemical, and biological feature.. Thi area repreented a ediment logical, morphological, geochemical, and biological barrier between a river and a receiving water body [2] Sedimentation occur naturally from eroion of oil in the catchment area.it had the degree of everity depending on the topography, oil type, vegetation cover and intenity of rainfall. Importantly, the preence of human activitie uch a agriculture, livetock rearing, burning and deforetation within the catchment affect the rate of edimentation. The rate edimentation could be reduced by changing catchment management [3,4]. Coban Ronda Sub-waterhed wa one of waterhed in Indoneia with high eroion rate. Some factor increaed the eroion rate there wa a follow: 1) the topography wa hilly and loping; 2) rainfall and eroivity wa o high; 3) irrigation area wa o narrow o that increaed intenification and it impacted eroion; and 4) there wa foret cutting wildly.if the eroion wa o high, it wa impacted edimentation in Selorejo Dam.. MATERIALS AND METHODS Location of tudy wa in Cobanrondo Sub-waterhed, malang Regency of Indoneia. Thi tudy wa carried out uing decriptive analyi and field experiment. Map of location wa a in Figure 1 below, *Correponding Author: Bambang Suharto, Faculty of Agriclutural Technology, Univerity of Brawijaya, Malang, Indoneia. bambang@ub.ac.id 593

2 Suanawati and Suharto, 2012 PETA THIESSEN SUB DAS COBAN RONDO U SKALA 1 : LEGENDA : Sta. Kedungrejo (1068,11 Ha) Sta. (768,06 Ha) SUMBER : PROYEK KALI KONTO ATA 206 Figure 1 Map of Cobanrondo Waterhed Experiment deign of actual eroion meaurement Direct eroion meaurement with field experiment wa carried out during rainy eaon (November 2009 to January 2010) and verification of model wa done at April There wa built oil torage (drum) below the location. It meaned for meauring the eroion oil. The meauring of experiment quare wa uitable to field condition and it wa elected the widet quare. Square retriction wa made from mall heap of oil. It wa intended to block inflow to and outflow from eroion quare. Surface runoff and eroion flowed through runoff channel which wa built more loping to anticipate the edimentation. After runoff and eroion flow through the apron, it wa tored in runoff torage. If there wa much urface runoff, it wa not able to tore all volume of urface runoff. To olve thi cae, there wa made diveder at the torage. Surface runoff which wa tored in econd and third drum wa only 1/15 of volume, but the other one wa outide drained. The hape of building plot tet wa decribed a in Figure 2 below.the number and detail of plot tet wa decribed a in Table 1 below. Figure 1 Plot Tet Building of Eroion and Runoff 594

3 J. Baic. Appl. Sci. Re., 2(1) , 2012 Table 1 Number of eroion Plot Tet Land ue Rainfall tation Type of oil Type of plantation Area (ha) Plot Tet Natural foret Ngaglik Andool Wooden tree +ereah 0,250 1 Production foret Pynu 0,250 1 Natural foret Tlekung Andool Wooden tree+ereah 0,250 1 Production foret Pynu 0,250 1 Natural foret Kedung Andool Wooden tree+ereah 0,250 1 Production foret Rejo Pynu 0,250 1 Shrub+ Stoney oil Tlekung Andool Shrub 0,250 1 Andool Caava 0,250 1 Gra 0,100 1 Cambiol Corn 0,039 1 Mediteran Mixed garden Corn 0,200 1 Ngaglik Andool Caava 0,200 1 Gra 0,100 1 Rainy caugh Irrigated area Kedung Rejo Andool Andool Cambiol Mediteran Corn 0,200 1 Caava 0,200 1 Gra 0,100 1 Caava 0,250 1 Potato 0,100 1 Gogo rice 0,100 1 Soja 0,100 1 Soil Peanut 0,250 1 Soil peanut+tunggak peanut 0,200 1 Caava + oja 0,200 1 Caava + oil peanut 0,200 1 Caava 0,250 1 Potato 0,100 1 Gogo rice 0,100 1 Soja 0,100 1 Soil peanut 0,250 1 Soil peanut+tunggak paenut 0,200 1 Caava + oja 0,200 1 Caava + oil peanut 0,200 1 Caava 0,250 1 Potato 0,100 1 Gogo rice 0,100 1 Soja 0,100 1 Soil peanut 0,250 1 Soil peanut +Tunggak peanut 0,200 1 Caava + oja 0,200 1 Caava + oil peanut 0,200 1 Number of eroion plot tet 51 Total volume of runoff = vol.ap + vol.i + 15 vol.ii + 15 vol.iii Analyi of oil weight: There wa taken 1 l ampel from drum bae. The weght of oil wa determined by filtering it. For example: if oil weight at 1 liter olution = X gram, then oil weght at drum I (D I), drum II (D II) and drum III (D III) wa a follow: 595

4 Suanawati and Suharto, 2012 D I D II X I gram vol. of. water D I 1liter X II gram vol. of. water D II 1 liter X III gram D III vol. of. water D III 1liter Actual total weight of oil loe (Ea) = Ap + D I + 15 D II + 15 D III Soil weight had to be expreed a oven dry weight. After the meaurement of apron and drum, it wa immediately to be cleaned becaue it would ue to tore the next runoff and erion. Actual eroion rate and oil loe depth RESULTS AND DISCUSSION Actual eroion at the firt period of plot tet wa oberved on November 1, 2010 until November 30, Recapitulation of actual eroion rate and oil loe depth on the firt period wa decribed a in Table 2 below. Table 2 Recapitulation of actual eroion rate and oil loe depth at the firt period of plot tet Land ue Rainfall Type of oil Type of plantation Ea Actual Soil loe depth (mm) tation (ton/ha) Natural foret Ngaglik Andool Wooden tree + 0,084 0,006 ereah Production foret Pynu 51,446 3,607 Natural foret Tlekung Andool Wooden tree + 0,171 0,012 ereah Production foret Pynu 26,230 1,839 Natural foret Kedung Andool Wooden tree + 0,256 0,018 Rejo ereah Production foret Pynu 157,057 10,897 Shrub + Tlekung Andool Shrub 1,171 0,082 Stoney oil Corn 4,292 0,301 Ngaglik Andool Caava 2,161 0,152 Mixed garden Gra 1,379 0,097 Red pepper 8,787 0,616 Corn 16,909 1,185 Kedung Andool Caava 6,247 0,438 Rejo Gra 1,246 0,087 Red pepper 10,084 0,707 Baed on the reult a in Table 2 above, the highet actual eroion rate wa occured on the land ue of production foret (Pynu). Kedung Rejo rainfall tation wa there and type of andool had number area of ton/ha. The actual eroion rate wa uitable to oil loe depth of mm. Kedung Rejo rainfall tation had rcorded the highet rainfall among other tation there. It wa the ame a according to Utomo [4] that the higher oil lope would produce the higher eroion. Aryad [5] alo aid that oil in below the lope had higher eroion than in upper one. Actual eroion at the econd period of plot tet wa oberved on December 1, 2010 until December 31, Recapitulation of actual eroion rate and oil loe depth on the fecond period wa decribed a in Table 3 below. 596

5 J. Baic. Appl. Sci. Re., 2(1) , 2012 Table 3 Recapitulation of actual eroion rate and oil loe depth at the econd period of plot tet Land ue Mixed garden Rainy caugh Irrigated area Rainfall tation Type of oil Type of plantation Ea Actual (ton/ha) Soil loe depth (mm) Corn 3,434 0,241 Andool Caava 1,338 0,094 Gra 0,182 0,013 Red pepper 1,079 0,076 Cambiol Corn 1,232 0,087 Mediteran Corn 1,693 0,117 Corn 1,867 0,131 Caava 0,883 0,062 Red pepper 6,334 0,444 Andool Potato 0,332 0,023 Gogo rice 0,312 0,022 Soja 0,249 0,017 Soil peanut 0,149 0,010 Soil peanut+tunggak peanut 0,252 0,018 Caava+oja 0,120 0,008 Caava+Soil peanut 0,145 0,010 Actual eroion at the third period of plot tet wa oberved on January 1, 2010 until January 31, Recapitulation of actual eroion rate and oil loe depth on the fecond period wa decribed a in Table 4 below.. Table 4 Recapitulation of actual eroion rate and oil loe depth at the third period of plot tet Land ue Rainy caugh Irrigated area Rainfall tation Type of oil Type of plantation Ea Actual (ton/ha) Soil loe depth (mm) Corn 1,511 0,106 Caava 0,743 0,052 Red pepper 1,028 0,072 Cambiol Potato 2,624 0,184 Gogo rice 3,261 0,229 Soja 3,263 0,229 Soil peanut 2,530 0,178 Soil peanut+ Tunggak peanut 6,339 0,445 Caava+oja 1,461 0,103 Caava+oil peanut 2,263 0,159 Corn 0,718 0,040 Caava 0,351 0,020 Red pepper 2,787 0,156 Mediteran Potato 0,379 0,021 Gogo rice 0,449 0,025 Soja 0,219 0,012 Soil peanut 0,260 0,015 Soil peanut+ Tunggak peanut 0,562 0,031 Caava+oja 0,186 0,010 Caava+oil penut 0,666 0,037 The relation between actual eroion rate (Ea actual) and oil loe depth at firt, econd, and third period wa decribed a line equation and coefficient of determination a in Figure 3 below. 597

6 Suanawati and Suharto, 2012 o i l Kedalaman Kehilangan Tanah (mm) l o e d e p t h (mm) CONCLUSION y = x R 2** = Ea Ea Actual Aktual (ton/ha) (ton/ha) Figure 3 Relation between actual eroion rate (Ea actual) and oil loe depth at firt, econd, and third period a 1. Actual eroion rate in Coban Rondo Sub-waterhed due to oberved reult, meaurement, and reearch wa more than the allowance of limitation. It would impact the oil loe depth. 2. The higher actual eroion rate in Coban Rondo ub-waterhed would caue the higher oil loe depth. 3. The relation between actual eroion rate and oil loe depth in Coban Rondo Sub-waterhed could be repreented by the equation of Y = 0,0695 X + 0,0002, in which X wa actual eroion rate. REFERENCES 1. Starodubtev, V.M; and Trukavetkiy/ Deertification Procee in the Lli River Delta under Anthropogenic Preure. Journal of Water Reource Vol 38 (2) p Nikanorov, A.M.; Bryzgalo, V.A.; Komenko, L.S.; and Rehetnyak, O.S Anthropogenic Tranformation of Aquatic Environment Compoition in the Lena River Mouth Area. Journal of Water Reource Vol 39 (2) p Predan, Dcepa; Anev, Tihomir; Dryuan, Ro; and Harri, Michael, Management of Water Reervoir (Embung) in Wet Timoe, Indoneia, Journal of Water Reource Manage, 2011 (25): Utomo, W.H Eroi dan konervai Tanah. Penerbit IKIP Malang. Malang 5. Aryad, S Konervai Tanah dan Air. Penerbit Intitut Pertanian Bogor. 598