Type of Tide in Gembong Watershed, Pasuruan Regency, East Java of Indonesia

1,*Laksono D. Nugroho, 2M. Bisri, 2Lily Montarcih, 2Aniek Masrevaniah

1Doctoral Program of Water Resources Engineering, Faculty of Engineering, University of Brawijaya, Malang, East Java of Indonesia 2Department of Water Resources, Faculty of Engineering, University of Brawijaya, Malang, East Java of Indonesia

ABSTRACT

The aim of this study was to determine the type of tide in Gembong watershed. Based on the estimation ebb- tidal from Dishidros Army between 2007 - 2011 which was occured surrounded the Gembong watershed (Karang Kleta Port, Surabaya Port, and Kalianget Port), it was obtained the type of ebb-tidal by using Admiralty Method. Results showed that Mixed type had a trend to single daily. It was due to the observation data of July 3 until July 17 in the year of 2012 with the value of R was 1.08. This result was the same as the analysis result of Dishidros Army in surround of Gembong watershed for the same type. KEYWORDS: type of tide, Admiralty, Gembong watershed.

INTRODUCTION

The effect of river variable flows on the process of fluvial geomorphologic has only received the adequate attention in dry land environment [1]. However many variables of river do not suitable to the category of dry land rivers as defined by geo-morphologists even though they may experience the similar hydrology in variability term [2]. Ebb-tide is as the fluctuation of sea water level because there is pulling power of objects in the sky especially sun and month due to the mass of sea water in the earth. Although the mass of moon is much smaller than the mass of sun, but because of the distance to the earth was much nearer, so the influence of pulling power of moon to the earth is bigger than pulling power of sun. The pulling power of moon which influences ebb-tidal is 2.20 times than pulling power of sun. The knowledge of ebb-tide is very important in designing of shore structure and port. The highest elevation of water level (tidal) and the lowest one (ebb) are very important for designing the structure. For example, the crest elevation of wave breaking structure, quay- wall, etc are determined by elevation of tidal water level [3], while the depth of sailing line or port is determined by ebb water level [4]. The characteristic or parameter of ebb-tide included amplitude of ebb-tidal, angular velocity of ebb-tidal, time of observation, delay angle of ebb-tidal, and the average of ebb-tidal [5]. Maghrebi et.al [6] has estimated the discharge in ebb-tidal river by formulating the model of partially return flow. This formulation can estimate isohel contour in long section of submerged straight and irregular channel by differentiating roughness and geometry of channel [7]. Based on the comparison between the results of Maghrebi et.al formula and field measurement with ADC propeller (an Acoustic Doppler Current Propeller) it indicated that total of error was very small by measuring velocity of horizontal section. Type of ebb-tidal is determined by the frequency of ebb and tidal water every day, because the difference of response in each location due to the generation power of ebb-tide. If a river system or waters experiences one time of ebb and one time of tide in a day, so the waters area is said to have diurnal tides, but if there occurs two times of ebbs and two times of tidals in a day, the type is called as semidiurnal tides. The other type of tide is as the transition between single and double type and it is called as mixed tides. The mixed type is classified into two types such as double and single dominating mixed type [7]. Based on the prediction data of tide from Dishidros Army in the year of 2007-2011 due to the Admiralty Method in surround of Gembong Watershed- Pasuruan Regency such as Karang Kleta Timur Surabaya, Surabaya Port, and Kalianget Port was classified as mixed type and it had the trend to single daily. This study intended to know the type of tide in Gembong Watershed based on the observation data in field which was carried out from July 3, 2012 until July 17, 2012.

MATERIALS AND METHODS

This study was conducted in Gembong Watershed with the number area of 58.71 km2, the length of main river of 24.03 km, the average slope of 0.00196, and the roughness coefficient of 0.035. There is no forest in the upstream of watershed. The average width of Gembong River is about 50.00 m in the downstream where in coastal area there is mangrove in left and right side of river and few dyke. In surrounding river estuary, there is *Corresponding Author: Laksono D. Nugroho, Doctoral Program of Water Resources Engineering, Faculty of Engineering, University of Brawijaya, Malang, East Java of Indonesia. Email: [email protected]; [email protected]

827 Nugroho et al.,2013 used traditional navigation line because the effect of tide so that the ship can lean in and out from coastal area until 500 m to the upstream of river. In the middle of Gembong River has been crowded with population resudential area of Pasuruan city. In the upstream the resudential area is decreasing and there are some irrigated rice field and dry field but no forest area in Pasuruan Regency. Generally, the topography condition of Gembong Watershed is relatively plain with the elevation between + 1,00 – 55,00 m DPL. Map of study location is as in Figure 1. Figure 2 presented map of port location.

Gembong N Watershed

Pasuruan P.3.G.I

K Gembong Legend : Districts AWLR Gembong A WL R Gembong-Warungdowo Weir Watershed Boundaries 12960.62m Rainfall Station Oro-oro Pule Kejayan P.3.G.I Selowongko Wonorejo Wonorejo A : 58,71 km 2 Lc : 12,96 km L : 24,03 km

5211.16mOro-oro Pule

Selowongko

Figure 1 Map of study location (Source: UPT Balai Gembong-Pekalen Sampean Pasuruan)

Java Sea

Karang Jemuang Port, R=6.15 Coordinat X : 691015.11 eY : 9233887.32 Kalianget Port, R=1.14 135 Km Coordinate : X : 825076.87 Y : 9218905.91 Bangkalan Sumenep 30 Km Madura Island 134 Km Surabaya Port, R=1.07 Pamekasan Gresik Coordinate : X : 691371.81 Sampang Y : 9203068.99

Karang Kleta Port, R=0.82 130 Km Surabaya 20 Km Coordinate : X : 706398.70 Y : 9190498.20 35 Km Madura Bay Sidoarjo

Pasuruan Port, R=1.08 Coordinate : X : 711428.97 Y : 9155790.10 Pasuruan

Probolinggo

East Java

Indonesia Ocean

Figure 2 Map of port location (Source: UPT Balai Gembong-Pekalen Sampean Pasuruan)

828 J. Basic. Appl. Sci. Res., 3(2)827-831, 2013

Some data included primary and secondary one were used in this study. These data included as follow: 1. Daily rainfall of the last ten years from the station of watershed. 2. Cimate data of the last five years from the station of watershed. 3. Data of main river in watershed that included the length, capacity, and slope of existing river segment. 4. Data of available intake in watershed. 5. Data of AWLR (Automatic Water Level Recorder) on river. 6. Data of tide-ebb depth on river from national navy of Indonesia. 7. Observed data of the highest tide when rainy season and the lowest ebb when dry season. 8. Topography map with the scale of 1 : 25,000. 9. Surface geology data from General Directorate of Geology and Mineral Resources in Bandung. 10. Land cover data of watershed and land cover data of watershed from google earth.

In summary, the primary and secondary data which is used in this study included: 1) Predicted data of Dishidros Army in the year of 2007-2011 included the data in Karang Kleta Port, SurabayaPort, Karang Jamuang Port and Kalianget Port; 2) Topography data with the scale of 1 : 25,000; 3) Observation data of tide in Gembong Watershed by installing the Peilschale and the tide change was observed on July 3, 2012 until July 17, 2012.

Determination of tide type will be proved with the formulation as follow [7]: R = {[A (K1) + A (O1)]/[A(M2) + A(S2)]} ……………………………… (1) Note: R ≤ 0.25 semidiurnal type (single) 0.25 < R < 1.50 mixed type (mixed) 1.50 < R diurnal type (single)

Type of tide in Indonesia as above was presented as in Figure 3 [1].

GEMBONG WATERSHED

Figure 3. Distribution of tide in Indonesian Waters [4]

This study investigate observed flood hydrograph on river and tide-ebb of sea water in downstream of watershed based on tide-ebb researched data in the field and recording of available AWLR data in watershed for the recording of flood water level depth, tide-ebb data of sea water from national navy of Indonesia, and the other supporting data. Hydrograph Model which was influenced by sea water tide-ebb was built by using the data of flood water depth of AWLR, observed tide-ebb, and tide-ebb from national navy of Indonesia. The steps of analysis for building this model were as follow: 1) To analyze river hydrograph shape; 2) To analyze the pattern of sea water tide-ebb; 3) To analyze hydrograph shape due to tide-ebb sea water; 4) To analyze hydrograph model in river which is influenced by sea water tide-ebb; and 5) To obtained the verificated hydrograph model.

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RESULTS AND DISCUSSION

Data Analysis of Dishidros Army Based on the tide list of Dishidros Army from 2007 until 2011(5 years), it was obtained the tide type in study location at surrounding navigation line in Karang Kleta Port, Surabaya Port, and Kalianget Port. It was obtained constant data (Tidal Constant) due to the first formulation as above with R = 0.82; R=1.07; R =1.14; and approximate to 1.50 (Table 1 and Figure 2) shows that the study location of Gembong Watershed, Pasuruan Regency is indicated as mixed type and had the trend of single daily, the results are the same.

Table 1 Tide type in surround of location study

Constant No Location Year Conclusion K1 Q1 M2 S2 R 1 Karang Kleta Port 2007 45 27 59 29 0.82 Mixed 2008 45 27 59 29 0.82 Mixed 2009 45 27 59 29 0.82 Mixed 2010 45 27 59 29 0.82 Mixed 2011 45 27 59 29 0.82 Mixed

2 Surabaya Port 2007 47 28 44 26 1.07 Mixed 2008 47 28 44 26 1.07 Mixed 2009 47 28 44 26 1.07 Mixed 2010 47 28 44 26 1.07 Mixed 2011 47 28 44 26 1.07 Mixed 3 Karang Jamuang 2007 54 26 5 8 6.15 Diurnal 2008 54 26 5 8 6.15 Diurnal Port 2009 54 26 5 8 6.15 Diurnal 2010 54 26 5 8 6.15 Diurnal 2011 54 26 5 8 6.15 Diurnal

4 Kalianget Port 2007 42 24 39 19 1.14 Mixed 2008 42 24 39 19 1.14 Mixed 2009 42 24 39 19 1.14 Mixed 2010 42 24 39 19 1.14 Mixed 2011 42 24 39 19 1.14 Mixed

Source: Dishidros Army, 2007-2012

Analysis of observation data Field observation of tide was carried out in Gembong Watershed by installing peilschale at surrounding 500 m from coastal border enter to Gembong River during 15 full days from July 3, 2012 until July 17, 2012 by recorded the change of tide every 30 minutes. The result of tide curve was presented as in Figure 3. It is showed that Gembong River was as mixed type and had the trend of single daily. By using the first equation of Admiralty Method as above, it was obtained the constant which was used to determine the tide type in Gembong Watershed, Pasuruan Regency (Table 2). The value of R was = 1,08 which was approximate to 1.50. It meaned that occured tide type based on the field observation in Gembong River was as the mixed type and had the trrend of single daily.

830 J. Basic. Appl. Sci. Res., 3(2)827-831, 2013

Curve of tide, location of Gembong Watershed

4 Observation time: July 3, 2012 to July 17, 2012

2 (m) Elevation

t (hour)

Figure 3 Curve of tide in Gembong Watershed (July 3, 2012 to July 17, 2012)

Table 2 Type of tide in Gembong Watershed No Location Year Constant Conclusion K1 Q1 M2 S2 R 1 Gembong Watershed 2012 0.52 0.14 0.45 0.16 1.08 Mixed type Source: Observation result and analysis in 2012

CONCLUSION

Based on the observation of tide on July 3, 2012 to July 17, 2012 and analysis by using Admiralty Method as above, it was concluded that Gembong Watershed had mixed type of tide and trend of single daily. Prediction result by Dishidros Army by using Admiralty Method in surround of navigation line in Karang Kleta Port, Surabaya Port, and Kalianget Port indicated the same as observation result in Gembong Watershed.

AKNOWLEDGEMENT

This study was part of disertation in Doctoral Program of Water Resources, Faculty of Engineering, University of Brawijaya, Malang, East Java of Indonesia. The author is very thankfull to the Dishidros Army which has supported tide data and UPT Balai Gembong Pekalen Sampean in Pasuruan which has permitted to support research conducting in the location of Gembong Watershed, Pasurusn Regency.

REFERENCES

1. Grenfell, SE & Ellfay, WN, 2009. Hydrology, Sediment Transport Dynamics and Geomorphology of a Variable Flow River: the Mfolozi River, South Africa, http://www.wrc.org.za 2. Andawayanti, Ussy, 2010. Sediment Transport in Estuary in Bang River, Malang, Indonesia. International Journal of Academic Research, 2(5) Sep 2010: 224-226 3. Masrevaniah, Aniek and Rusdiansyah, 2012. Hydrodynamic Modeling on the secondary Channel of Irrigation Tidal Unit at South Kalimantan. Journal of Applied Environment and Biological Sciences, 2(6): 183-192 4. Triatmodjo, B., 1999. Teknik Pantai. Cetakan I. Yogyakarta. Penerbit Betta Offset. Yogyakarta. 5. Sewoko, A , Roehdyanto, S dan Sudira, P. 2003. Model Matematis Salinitas Air di Muara Sungai Untuk Pengairan Tambak Udang Windu, Jurnal Agritech Vol.23 No.4 : 200-204. 6. Maghrebi, M.F., and Givehchi, M., 2010. Discharge Estimation in a Tidal River with Partially Reverse Flow. Journal of Waterway, Port, Coastal, and Ocean Engineering. ASCE. 266-275. September/Oktober 2010. 7. Kodoatie, R.J., dan Sjarief, R., 2010. Tata Ruang Air. Edisi I. Penerbit Andi. Yogyakarta.

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