Simulation Plan Hydraulic Polder Banger System

on the Flood of Rob City of Semarang

Ikhwanudin

, S Imam Wahyudi

and Soedarsono

Doctoral Program of Civil Engineering, Professor of Civil Engineering, Senior Lector of Civil Engineering, Indonesia

Doctoral Program of Civil Engineering, Professor of Civil Engineering, Senior Lector of Civil Engineering

Keywords: Storage Variation, Catchment area, Pump.

Abstract: Flood is a common problem that occurs in some parts of Indonesia, especially in densely populated areas such

as in urban areas, The cause of the flood itself can occur due to various things both natural and human. Flood

that occurred in Semarang Central Java, in general is caused by several problems among them due to the

increase in discharge, base silting of river body and river narrowing due to sedimentation, Catchment area

and also caused by the imbalance between the incoming water, water coming out on city drainage channels,

Another problem that often arises is the tide of the sea (Rob) in some parts of the territory that are subscribed

to a puddle due to rob. Furthermore, the frequency of rainfall was analyzed by Log Pearson Type III method,

Gumbel and Haspers, then calculated flood discharge plan with Rational method, Weduwen, and Haspers.

From the results of flood discharge planning analysis, to find out runoff used flood discharge when re-5 years,

with rainfall from Gumbel method R5 = 130.473 mm with Q5 average = 102.677 m3 / dt From the calculation

shows that there is an increase of flood water level that can no longer be accommodated by Banger times. The

research method is done by hydraulic simulation of robotic flood of Semarang city by comparing field data

and simulation through Catchment area variation, through storage variation, pump variation and through

monitoring / observation of water elevation For 100% storage while 50% Retention Pool and long storage

0.25%.

1 INTRODUCTION

Semarang is one of the areas that prone to the flood.

The main problem faced in Semarang is the problem

of the flood with a long pool. In addition, the problem

of drainage systems with reduced function and

capacity, increased drainage load due to land

conversion, saltwater intrusion, decreased soil

elevation symptoms, sea level rise as a result of global

warming, less optimal operation and maintenance and

law enforcement which is still low. To overcome this

problem required flood control strategy with various

techniques and technology.

In this activity, many flood simulation simulations

are performed on existing drainage and river systems

with numerical models. The simulation scenario starts

with studying the existing condition, the

normalization of the groove and the elevation of the

embankment, the manufacture of polder technology

to the offshore draft. The location of the research was

conducted in several watersheds from upstream to

downstream (estuary and offshore) and certain

locations that experiencing floods and puddles around

the city of Semarang. that until now cannot be

overcome.

The coverage of the current flooding area has been

widespread in some areas including the estuary of

Kali Plumbon, Kali Siangker around Achmad Yani

Airport, Karangayu, Kerobokan, Bandarharjo, along

the road in Mangkang, Tugu Muda area - Simpang

Lima to Kali Semarang, banger times, in Genuk from

Kaligawe to the Demak border (City Government of

Semarang, 2011). The main problem of Semarang

City drainage system is sea level rise as the result of

the global warming and land subsidence. In addition,

due to the decrease of the drainage/flood capacity

caused by sedimentation, garbage, illegal building,

increased drainage load due to land conversion that is

not followed by the return of recharge and catchment

function, operation and maintenance is not optimal

and law enforcement (law enforcement) still weak

(Wahyudi, 2010).

178

Ikhwanudin, ., Wahyudi, S. and Soedarsono, .

Simulation Plan Hydraulic Polder Banger System on the Flood of Rob City of Semarang.

DOI: 10.5220/0009008101780183

In Proceedings of the 7th Engineering International Conference on Education, Concept and Application on Green Technology (EIC 2018), pages 178-183

ISBN: 978-989-758-411-4

Some parts of the Semarang area are lowlands and

some of them are lower than the sea level, then this

area receives rainwater flow from upstream, local rain

and tidal water. Some simple polder system has been

applied in the city of Semarang including feather

drain subsystem, Tanah Mas, and Tawang. Some

simple polder system has been applied in the city of

Semarang including feather drain subsystem, Tanah

Mas, and Tawang. However, the system has not been

optimally functioned because of the problem of

retention pond capacity, channel condition and pump

capacity, and institutional management of the polder

system. In addition, due to land subsidence and sea

level rise in the North Coast of Central Java, although

there is no rain, in some areas in the north of

Semarang are inundated by seawater at high tide

called ROB. When the rainfall is high, the puddle area

has a more expansive area. Losses resulting from the

flood/puddle of rob the longer the increase over time

namely damage to residential buildings, factories,

residential areas, environments and other

infrastructure Global warming is indicated to be the

cause of sea level rise. When the atmosphere warms

up, the ocean surface layer will also warm up, so the

volume will expand and raise the sea level (Nguyen

et al., 2016).

Changes in sea level affect the life in coastal areas

and can drown some land through estuaries, river

networks and drainage.Changes in sea level affect the

life in coastal areas Another cause of tidal flooding in

Semarang City is land subsidence. Based on the

measurement and analysis of land acquisition in the

area around the Port of Tanjung Emas an average of

6.5 cm per year (Wahyudi, 2007).

In order to improve the condition and to anticipate

the possibility of increasing complexity of flood /

puddle problem, it is necessary to study the

phenomenon of the sea tide elevation increase and

land subsidence, modeled mathematically and

physically as the basis for drafting / handling of robot

handling concept Then the need to study similar cases

in some overseas advanced cities are more

experienced in handling, so as to develop an

implementation polder system especially in the city

of Semarang.

1.1 Problems

 Flood control with polder system in some

locations is still less optimal so that floods still

occur.

 Soil subsidence is slowly occurring in some

polder subsystems due to uncontrolled

groundwater extraction and has resulted in the

topography of the terrain at that location to be

lower than the flood waters so that in that

location floods and puddles are still occurring.

1.2 Research Purposes

The purposes of the study is to get a good formula for

the strategy of handling and managing the good and

efficient time of Banger Watershed. Then what needs

to be done is collecting data compartment with

experimental data below.

 To know the characteristics of Retention Pond

 To know Banger Polder Channel Capacity

 Formulate the Banger Polder System

1.3 Literature Review

Polder is an urban drainage handling system by

isolating the area served (catchment area) to the entry

of water from outside the area, either in the form of

overflow or subsurface flow (culvert and seepage),

and control the flood water level inside system

according to plan. Properties of Polder System

include:

 The polder region is well-defined, where water

from outside the area should not enter, only

rainwater and sometimes seepage water, in the

area itself collected.

 In polders there is no free surface flow as in

natural water catchment areas, but is equipped

with a control building at its disposal (with a

drain or pump) to control outflow.

 Water faces in polders (surface water or

subsurface water) are not dependent on the

water surface in the surrounding area and are

assessed by land elevation, soil properties,

climates, and plants. The polder system

component consists of These are 1) Mobile

embankment and / or sea defense, or other

insulation construction 2) Field drainage

system 3) Conveyance system 4) Storage pond

and outfall system 5) Water body recipient

waters (Segeren, 1982)

Based on the definition can be concluded that the

object of the polder system is an area with the

following characteristics: 1) Isolated as a unit of

hydrological system that is not affected by the

surrounding system, 2) Surface water and ground

water can be controlled in such a way, 3) Areas that

are in natural condition are often inundated (flood

area).The polder system is a closed water system with

embankment elements, pumps, conduits, retention

pools, landscape arrangements, municipal water

Simulation Plan Hydraulic Polder Banger System on the Flood of Rob City of Semarang

179

installations. This Polder system must work a unified

system and integrated with a more macro drainage

master plan (Wahyudi, 2012).

Polder system is a way of handling flood with

physical building, including drainage system,

retention pond, embankment that surrounds the area,

as well as pump and / door of water, as an integral

water management unit (Pusair, 2007). Construction

of polder system can not be done individually, but

need to be planned and implemented in an integrated,

adjusted to the spatial plan of the region and the water

system in a macro. The combination of pump capacity

and retention ponds should be capable of controlling

the water level in a polder area and not negatively

impacting the drainage system on a macro basis.

Completeness of physical facilities for polder system

include: embankment for insulation with seawater,

drains, retention ponds (tank) and pumps (Rosdianti,

2009)

The concept of a polder system is a concept of

closed water system using seepage embankments and

sluice gates so as to be the right solution in

overcoming the problem of flooding and inundation

in low areas (Wahyudi et al., 2017). In addition to

flooding from the sea, this system can also protect the

area in the embankment from floods due to rain

through a system of watering management (Mah et

al., 2011)

The polder system is built to prevent water from

flowing back into the system by using the pump in

case of rain. Water expenditure in the system can be

done by gravity when the water level in the river is

lower than in the system (Taborda & Riberio, 2015).

Based on the definition can be concluded that the

object of the polder system is an area with the

following characteristics: a. Isolated as a unit of

hydrological system that is not affected by the

surrounding system, b. Surface water and ground

water can be controlled in such a way, c. Areas that

are in natural condition are often inundated (flood

area).

There are several disadvantages of the polder

system: 1) In the drainage is done by pumping, this is

due to natural conditions, 2) High operational costs

compared to the gravity system. 2) If the pump

condition is disrupted then the pump can not operate

so the reservoir pump must be provided. 3) Cleaning

should be routine

1.4 Sea Level Rise

Global warming affects the weather, sea level, beach,

agriculture, wildlife and human health. When the

atmosphere warms up, the ocean surface layer will

also warm up, so the volume will expand and raise the

sea level. Changes in sea level will greatly affect

coastal life. A 100 cm increase would drown the

Netherlands, 17.5% of Bangladesh, and many islands.

When the high oceans reach the mouth of the river,

floods due to high tides will increase inland.

1.5 Land Subsidence

Indication of land subsidence in Semarang can be

known from several data sources. Based on

measurement and data of land subsidence in the hilly

area in Semarang city is smaller than the decrease in

coastal area. From field observations of land

subsidence in the former swamps and ponds showed

a decline the largest, for example in Tanah Mas

housing, Tanjung Mas Beach, with a decrease

between 5.5 - 7.23 cm per (Marfai & King, 2008).

2 RESEARCH METHODOLOGY

The data collection used in this study consisted of

primary and secondary data. Primary data is data

obtained directly from the object of research in the

field or can be an interview to the parties concerned.

While the secondary data is obtained from related

institutions that have the completeness of the data as

needed eg topographic map, flood discharge data,

land use map, drainage network system data, tidal

data and sea water waves and data of land subsidence

(landsubsidence).

3 RESULTS AND DISCUSSION

3.1 Catchment Area Polder Banger

Polder Banger has a catchment 675 ha area, located

in East Semarang, has a river length of 13,326 km

This Polder has its equipments which include

retention pond area of 9.8 Ha and 5 pumps with

capacity of 2 m3 / sec. When the retention pond is still

a natural reservoir. The Kali Banger Polder System

has an infrastructure component comprising (Mondel,

2009) Northern dike (North Artery Dam

Arrangement), protecting the Kali Banger Polder area

from sea level, Eastern dike (East Flood Canal Flood)

protecting the Polder area from the East Flood Canal

River, Dam Banger River (Pembangunan Bendung

K.Banger) that closes the flow connections from the

Polder region to rivers and seas, currently where

temporary shutdowns are located downstream near

EIC 2018 - The 7th Engineering International Conference (EIC), Engineering International Conference on Education, Concept and

Application on Green Technology

180

the pumping station Pumping station is enabled to

control the water elevation because the Polder area is

covered by a weir, Retention basin (Retention Pond)

is used for system water level control polder before

pumping.

Water elevation in the retention pool is controlled -2

m MSL natural retention pool of large polder banger

that is 9.6 ha using 5 pumps with capacity of 2 m

/ s.

Figure 1 Catchment area polder Banger.

The boundary embankments around the Banger

polder basin are as follows:

1. north: Java Sea

2. south: Jl. Brigadier Katamso;

3. west: Kali Baru and Kali Semarang;

4. east: East Flood Canal Levee

Folder-based analysis with scale of 1.5000 in wide

catchment area of banger 675 ha

3.1.1 Rainfall Analysis

The intensity of rain is the rainfall that occurs during

a period of time when the water is concentrated. The

general nature of the rain is the shorter the rain the

intensity tends to be higher and the greater the

repetition period the higher the intensity (Suripin,

2004)

To find the polder effectiveness measured by the

polder's ability to control flooding. The first step is to

find the average rainfall. one of the calculation of

rainfall intensity is using Mononobe method. As seen

in Equation (1).

I

24









/

(1)

Where, I is the rainfall intensity (mm / hour), R24

is an annual maximum annual rainfall for the year t

reset (mm) and tc referes to concentration time

(hours).

Rain depth is determined by Hyeteograph

calculation using Alternating Block Method (ABM)

method. From the value of Hyeteograph can be

obtained Rain Effective with the formula as presented

in the equation. (Triatmodjo, 2008).

Pe 



,





,

(2)

Where, Pe is an effective rain depth (mm), P is the

rain depth (mm) and S is for maximum water

potential retention by soil, which is mostly due to

infiltration (mm).

Based on the rainfall analysis, the analysis of

rainfall frequency using Log Pearson Type III,

Gumbel and Haspers method, Flood discharge plan

with Rational method, Weduwen, and Haspers. From

the results of flood discharge planning analysis, to

find out the runoff used flood discharge when re-5

years with rainfall from Gumbel method R5 =

130.473 mm.

3.1.2 Flood Debit Analysis Plan

In the case study on the flood problem of Kali Banger

Kota Semarang, it begins with secondary data

collection related to location and inventory of rainfall

data and data of existing condition of Banger River.

Furthermore, the analysis of rainfall frequency using

Log Pearson Type III, Gumbel and Haspers method,

then calculation of flood discharge plan with

Rational, Weduwen and Haspers method. From the

results of flood discharge analysis of the plan, to find

out the runoff used flood debit when re-5 years with

rainfall from Gumbel method R5 = 130.473 mm with

Q5 average = 102.677 m

/dt. From the calculation

shows that there is an increase in flood water level

Simulation Plan Hydraulic Polder Banger System on the Flood of Rob City of Semarang

181

that can no longer be accommodated by Kali Banger.

To know the runoff used flood discharge when re-5

years with rainfall. From the calculation results show

that the increment of flood water level that is no

longer able to be accommodated in banger times, and

briefly the calculation of flood analysis Concluded

the design flood discharge obtained certain periods

for example for Q5th the discharge used is 130.473

/dt

Tabel 1: Flood discharge design.

Return Perio

Year’s

Q Average Design

(

/dt)

2 96.56

5 102.67

10 120.33

20 128.44

25 131.28

50 138.52

Flood debit analysis at Banger times is

summarized in graph (rating-curve) which shows the

relationship between flood discharge (m

/dt) and time

(hours). Where the maximum discharge (Qmax-5th)

was obtained for 102.677 m3 / dt.

Figure 2: Flood of Banger times.

3.1.3 Hydrograph Unit Analysis

The first step to find out the correlation model of

catchment area, water storage, pump capacity in

polder system is data collection of rainfall data

obtained, conducted hydrological analysis resulting

in flood discharge plan, which then processed again

to find the amount of flood routing which result is

used to determine elevation of embankment.

Hydrological analysis for retention pool planning

includes four activities:

 Incoming flow (inflow) that fills the flood

retention pool plan to determine the capacity

and dimension of the embankment

 Pool retention count.

 Outflow (outflow) to determine the amount of

water that comes out.



Figure 3: Graph of Inflow and Outflow (with pump) on

Banger polder.

3.1.4 Simulation the Effectiveness of

Discharge and Pump

The highest flood discharge called inflow will be

compared to the highest plan pump capability called

outflow. This comparison is called the effectiveness

and can be seen the percentage of performance of

each polder. The effectiveness of the pump with the

formula as in Equation 3 below.

 









 100%

(3)

The effectiveness of pumps obtained in Kali

banger Polder. That is, after the construction of

Polder Kali Semarang, the amount of water discharge

into the drainage network system can be minimized

The effectiveness of pumps obtained in Polder

Banger sebsebsar 56% That is, after the builder

Polder Banger, the amount of water discharge into the

drainage network system can be minimized by 56% .

3.1.5 Hydraulic Simulation Plan Polder

Banger Laboratory

This simulation compares field data with the

experiment through variations of Catchment area,

storage variation, pump variation and monitoring and

water elevation observation for this simulation

comparison between storage of retention pool and

longe storage. For storage 100% while Retention Pool

50% and Lang storage 0.25%.

EIC 2018 - The 7th Engineering International Conference (EIC), Engineering International Conference on Education, Concept and

Application on Green Technology

182

Figure 3: Scheme of Banger hydraulic polder simulation.

(A: Water reservoir; B: Catchment Area; C: Lang storage;

D: Pump; E: The Sea).

4 CONCLUSION

Flood and Rob occurred in the city of Semarang due

to the phenomenon of sea level rise and land

subsidence. Polder system to isolate seawater flow

and control water elevation with pumps, conduits,

ponds, embankments and weirs or gates. To

overcome this phenomenon must know the capacity

of Tonson, Pump and channel.

ACKNOWLEDGMENTS

Acknowledgments to RISTEKDIKTI for Research

Grant, Promoter and Co Promoter in this research and

PSDA Semarang city which has given place for

research.

REFERENCES

Wahyudi, S. I., 2010. “Perbandingan Penanganan Banjir

Rob Di La Briere ( Prancis ), Rotterdam ( Belanda ) Dan

Perspektif Di Semarang ( Indonesia )”, Jurnal Riptek,

Vol. 4, No. 2, pp. 29–35.

Nguyen, T. T. X., Bonetti, J. , Rogers, K. & Woodroffe, C.

D. 2016. “Indicator-based assessment of climate-

change impacts on coasts: A review of concepts,

methodological approaches and vulnerability indices”,

Ocean and Coastal Management, Vol. 123. pp. 18 – 43.

Wahyudi S. I., “Tingkat Pengaruh Elevasi Pasang Laut

Terhadap Banjir dan Rob di Kawasan Kaligawe

Semarang”, Jurnal Riptek, Vol. 1, No. 1, pp. 27–34.

Segeren, W. A., 1982. “Introduction to the keynotes of the

international symposium Polders of the World. In: Final

report of the international symposium Polders of the

World”, in International Symposium Polders.

Wahyudi, S. I., Ni’am, M. F. & Gilbert, L. B., 2012.

“Problems, Causes and Handling Analysis of Tidal

Flood, Erosion and Sedimentation in Northern Coast of

Central Java: Review and Recommendation”, Journal

of Civil and Environmental Engineering, Vol. 12, No.

4, pp. 65–69.

Pusair, P., 2007. Sistem Polder untuk Perkotaan Rawan Air,

Bandung, Indonesia.

Rosdianti, R., 2009. Banjir dan Penerapan Sistem Polder,

Jakarta, Indonesia.

Wahyudi, R. P. S. I., Heikoop, R., Adi, H. P., Overgaauw,

T., Schipper, B., 2017. “Emergency scenarios in the

Banger polder, Semarang City A case study to identify

different emergency scenarios”, Water Practice and

Technology, Vol. 12, No. 3, pp. 637–648.

Mah, D. Y. S., Putuhena, F. J. & Rosli, N. A., 2011.

“Modelling of river flushing and water quality in a

tributary constrained by barrages” Irrigation and

Draination System, Management of Environmental

Quality: An International Journal, Vol. 23, No. 1, pp.

101 – 108.

Taborda, R. & Ribeiro, M. A., 2015. “A simple model to

estimate the impact of sea-level rise on platform

beaches”, Geomorphology, Vol. 234, pp. 204 – 210.

Marfai, M. A. & King, L., 2008. “Tidal inundation mapping

under enhanced land subsidence in Semarang, Central

Java Indonesia”, Natural Hazardz, Vol. 44, No. 1, pp.

93 – 109.

Mondel, H., 2009. Conceptual Design Report. The CEPC

Study Group, Beijing, China.

Suripin, S., 2004. Sustainability Drainage System. Andi

Offset, Semarang, Indonesia.

Triatmodjo, B., 2008. Hidrologi Terapan. Beta Offset,

Yogjakarta, Indonesia.

B C

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