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1. Title

Application of Mangrove Forest for Countermeasure Against Tsunami Disaster

ID: DRH 10 Avicena Apiculata Mangrove forest_at the Grajagan Coast_East Java.
Hazard: Tsunami , Storm surge
Category:

Implementation Oriented Technology (IOT)

Proposer: Dinar Istiyanto
Country: JAPAN; INDONESIA;
Date posted: 31 January 2008
Date published: 05 January 2009
Copyright © 2009 Dinar Istiyanto (proposer). All rights reserved.

Avicena Apiculata Mangrove forest_at the Grajagan Coast_East Java.

Contact

DINAR CATUR ISTIYANTO
Senior Research Engineer, Coastal Dynamic Research Center (CDRC), Agency for The Assessment and Application of Technology, Indonesia.

Present position: Research Specialist Fellow, International Center for Water Hazard and Risk Management (ICHARM, under the auspice of UNESCO, Public Works Research Institute (PWRI), Japan.

1. Coastal Dynamic Research Center BPPT, Jl. Grafika No.2, Sekip, Yogyakarta 55281, Indonesia.
Telp. 62-274-586239; Fax. 62-274-542789, e-mail: pakdinar@yahoo.com; dinar@webmail.bppt.go.id.

2. International Center for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan; Phone: +81-29-879-6809; Fax: +81-29-879-6709; e-mail: dinar55@pwri.go.jp;

2. Major significance / Summary

This implemented orientation technology has been developing to provide a tool for planning effective mangrove forest as tsunami damper at the beach.
A set of procedure is provided for the calculation of possible reduction of tsunami wave height and energy by the existing mangrove forest at certain area. On the other hand, the procedure is made enable for designing effective mangrove forest to reduce predicted tsunami conditions.

3. Keywords

mangrove forest, tsunami, disaster reduction, design


II. Categories

4. Focus of this information

Implementation Oriented Technology (IOT)

5. Users

5-1. Anticipated users: Community leaders (voluntary base) , Administrative officers , Municipalities , National governments and other intermediate government bodies (state, prefecture, district, etc.) , NGO/NPO project managers and staff , International organizations (UN organizations and programmes, WB, ADRC, EC, etc.) , Commercial entrepreneurs , Financing and insurance business personnel , Experts , Teachers and educators , Architects and engineers , Sociologists and political economists , Urban planners , Rural planners , Environmental/Ecological specialists

5-2. Other users: Policy makers , Motivated researchers , Local residents

6. Hazards focused

Tsunami , Storm surge

7. Elements at risk

Human lives , Human networks in local communities , Business and livelihoods , Infrastructure , Buildings , Urban areas , Coastal areas , River banks and fluvial basin , Agricultural lands


III. Contact Information

8. Proposer(s) information (Writer of this template)

DINAR CATUR ISTIYANTO
Senior Research Engineer, Coastal Dynamic Research Center (CDRC), Agency for The Assessment and Application of Technology, Indonesia.

Present position: Research Specialist Fellow, International Center for Water Hazard and Risk Management (ICHARM, under the auspice of UNESCO, Public Works Research Institute (PWRI), Japan.

1. Coastal Dynamic Research Center BPPT, Jl. Grafika No.2, Sekip, Yogyakarta 55281, Indonesia.
Telp. 62-274-586239; Fax. 62-274-542789, e-mail: pakdinar@yahoo.com; dinar@webmail.bppt.go.id.

2. International Center for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japan; Phone: +81-29-879-6809; Fax: +81-29-879-6709; e-mail: dinar55@pwri.go.jp;

9. Country(ies)/region(s) where the technology/knowledge/practice originated

JAPAN; INDONESIA;

JAPAN: Southern islands, e.g. Okinawa.
INDONESIA: e.g. Banyuwangi (East Java)

10. Names and institutions of technology/knowledge developers

1. Dinar Catur Istiyanto, Coastal Dynamic Research Center, Agency for The Assessment and Application of Technology, Indonesia.
2. Satrijo Karuniadi Utomo, Civil Engineering Department, State University of Semarang, Indonesia.
3. Widjo Kongko, Coastal Dynamic Research Center, Agency for The Assessment and Application of Technology, Indonesia.

11. Title of relevant projects if any

Research On Tsunami Hazard and Its Effects on Indonesia Coastal Region, 2001-2004

12. References and publications

1. Dinar C. Istiyanto, Widjo Kongko, Application of Mangrove Forest for Countermeasure Against Tsunami Disaster, Presented at DRH Content Meeting, EDM-NIED, Kobe, 2007.
2. Dinar C. Istiyanto, Implementation of Greenbelt Technique As Coastal Protection Against Tsunami: Experience With EqTAP Implementation Strategy and Expectation on DRH-Project, Presented at Asian Disaster Reduction Science and Technology Forum, EDM-NIED, Jakarta, 2006.
3. Dinar C. Istiyanto, Utomo, K.S., Suranto, Jauzi, M.Z., The Influence of Rhyzopora-Shrub on Tsunami Propagation at The Beach, Proceeding of National Seminar on Tsunami, JICA-CDRC, Indonesia, 2006, pp. 311-322 (in Indonesian language)
4. Utomo, K.S., Dinar C. Istiyanto, Suranto, Triatmadja, R., Yuwono, N., Hydraulic Characteristics of Mangrove Forest in Reducing Tsunami Energy, Proceeding of National Seminar on Tsunami, JICA-CDRC, Indonesia, 2006, pp. 323-340. (in Indonesian language)
5. Dinar C. Istiyanto, Suranto, Shadikin, A., Physical Hydraulic Modeling of Tsunami Runup Over Various Coastline Geometric, Proceeding of National Seminar on Tsunami, JICA-CDRC, Indonesia, 2006, pp. 81-92. (in Indonesian language)
6. Dinar C. Istiyanto, Investigating Tsunami Propagation at the Beach by Using Physical Model, Presented at National Workshop on Disaster Mitigation at Coastal Area, Ministry of Marine and Fisheries, Jakarta, Indonesia, 2003. (in Indonesian language)
7. Dinar C. Istiyanto, First Year Activities ? Research on Tsunami Hazard and Its Effects on Indonesia Coastal Region, Proceeding of the 5th Multi-Lateral Workshop on The Development of Earthquake and Tsunami Disaster Mitigation Technologies and Their Integration for Asia-Pacific Region, Bangkok, Thailand, 2002

13. Note on ownership if any


IV. Background

14. Disaster events and/or societal circumstances, which became the driving force either for developing the technology/knowledge or enhancing its practice

Asian countries, especially those are laid along “ring-fire” of Western Pacific Ocean (i.e. Japan, Korea, Philipine, Indonesia, Papua New Guinea, Pacific Islands) and Indian Ocean (i.e. Indonesia, India, Srilanka, Bangladesh), are the most tsunami prone areas. Between the years of 1600 to 2004 (ITDB,2004), 282 events of tsunami were recorded by which more than 361,000 death toll are sentenced. The biggest death toll contributions are from the tsunami event of 2004’ Indian Ocean (about 230,000) and 1883’ Krakatau eruption (36,000).

 

In order to reduce the risk of tsunami disaster, comprehensive tsunami disaster countermeasure is urgen tly necessary in these region. Among many complementing countermeasures, the idea of utilizing greenbelt as coastal protection against tsunami has been widely spread among engineers during last fifteen years, especially in the region where various beach trees well grown up naturally. Many post-tsunami site investigations showed that mangrove forest and other types of beach tree were found at many coastal areas where its shaded inland has less damage after tsunami attack. It is known that coastal forest stops driftwood and other floatages, reduces water flow velocity and inundation w ater depth and provides a live-saving means by catching persons carried out off by tsunami (Shuto, 1987).

 

Mangrove forest is not as expensive as hard structure like seawall or breakwater. Mangroves forest also have advantages on its environmentally friendly and its relatively economical cost of implementation. And, many coastal areas in the above mentioned region are appropriate for mangrove habitation.

 

 

 

Avicena_Apiculata_Mangrove_forest_at_Grajagan_Coast_of East-Java_

 

Avicena Apiculata Mangrove forest_at the Grajagan Coast_East Java

 


 


V. Description

15. Feature and attribute

This technology has been developing to provide engineering tool for planning coastal protection by using mangrove-forest or to appraise the effectiveness of existing mangrove forest in reducing potential tsunami wave height and energy.

The main required inputs are tsunami wave height and length as well as the expected inland reduced wave height. Tsunami wave height and length, along with the existing geomorphology of the objective beach, are the fix input parameters, whereas the expected inland reduced wave height is a variable according to the data of designed mangrove-forest density, mangrove-forest width (perpendicular to the coast line), and mangrove tree’s height.

Tsunami wave height and length are determined based on statistical analysis of historical event or numerically simulated one. Numerical simulation calculation must be conducted in advance by person or institution who is expert in this field.

Design parameters in this proposed technology are called together as hydraulic dimension of mangrove forest, which include hydraulic height of mangrove forest (d), hydraulic width of mangrove forest (BL) and hydraulic density of mangrove forest (e).  Determination of each parameter shall be refered to the following procedure. 

1.      Hydraulic height of mangrove forest (d)

                                      d = (d+ [1/(1 – KR )]H)/tB                                                               (1) 

 

where: d is water depth just at the seaward line of mangrove forest, KR is reflection coefficient of mangrove forest, H is design tsunami wave height just before interacts with mangrove forest and tB is average height of the trees in mangrove forest.  See Figure-1.

 

 

Figure-1. Diagram of variables related to the determination of d

      The value of d will contain KR variable as KR value is not yet determined. 

2.      Mangrove forest density (K)

Mangrove forest density (K) expresses parts of trees occupation in a space volume of mangrove forest.  This is the total volume of the trees (including roots, trunk, branches, and leafs if possible) divided by the total volume of space in which the total volume of the trees were measured.

 

        (total volume of trees in the measured area)

K = -------------------------------------------------------------------------------     (2)

         (total volume of space in which the total volume of the trees were measured)

 

Example: if the average height of mangrove trees is 5 m, and the unit area of magrove forest is 5m by 5m, hence the total volume of space in which the total volume of the trees is measured is 5m x 5m x 5m = 125 m3. If the measured total volume of the trees within this space is 5 m3, hence the forest density K is = 5/125 = 0.04.

3.     Hydraulic density of mangrove forest (e)

Hydraulic density of mangrove forest (e) is determined according to the value of mangrove forest density (K) and hydraulic height of mangrove forets (d).

     The d value shall be calculated by equation (1), whereas K is by equation (2). 

Based on the results of laboratorium experiment, the relations between e and d are provided for K equal to K1 = 0.0125 and K2 = 0.05 as in the equation (3) and (4). Linier interpolation shall be conducted for the K value between K1 = 0.0125 and K2 = 0.05. However, solutions for K < K1 and K > K2 are still not available at present.

For K = K1 = 0.0125,

                                                                                                                      (3)

For K = K2 = 0.05,

                                                                                                                      (4)

The above relation is derived from the following graphics in Figure-2.

 

 

Figure-2.    Graphics of relation between hydraulic density of mangrove forest (e), mangrove forest density (K) and hydraulic height of mangrove forest (d)

    

4.      Hydraulic width of mangrove forest (BL)

                                                BL = B/L                                                                              (5)   

where: B is the width of mangrove forest in the direction perpendicular to the coastline and L is tsunami wave length.

 

5.      The resulted value of e and BL are then inputted into equation (6), which is the correlation equation of KR and (e.BL) as it is also shown in the graphics of Figure-3.

                                                  KR = 0.0872 ln(e.BL) + 0.782                                          (6)     

  

 

Figure-3. Graphics of correlation between KR and (e.BL)

Accordingly, an equation with KR variable both in the left and right side will be derived.

This equation shall be solved by carrying out iteration procedure or trial and error calculation. KR shall be given initial value of 0 £ KR £ 1.

     

6.      Once KR is determined, the definite value of d and e could be calculated.

 

7.      Further, the value of transmission coefficient (KT) and transmitted wave height (HT) shall be calculated by refering to the equation (7), that is related to Figure-4, and equation (8) consecutively.

                                                   KT = -0.1644 ln(e.BL) - 0.4601                                      (7) 

                                                   HT =  KT.HIR                                                                 (8) 

      where :                                  HIR =  [1/(1 – KR )] H                                                    (9)

 

 

Figure-4.     Graphics of correlation between KT and (e.BL)

 

 

16. Necessary process to implement

The provided simple diagrams and equations shall be used directly to appraise the capacity of existing mangrove forest in reducing tsunami wave height or energy that passing through the forest into the shaded inland.

The provided diagrams and equations are also made enable to design mangrove forest width and density for preliminary planning of coastal protection against tsunami.

Any body has capability of reading graphics and diagrams and carrying out graphics interpolation will be able to make preliminary calculation for mangrove forest dimension and or prediction of mangrove forest capacity in reducing tsunami wave height. However a local multi-stakeholder workshop related to the application of this method (methodology, possibility, etc) is necessary before its implementation.

The result of calculation or prediction is implemented only for a unit length of mangrove in the tranversal direction paralled to the coast. In order to get more detil picture of tsunami inundation over wide coastal area, the users are suggested to use numerical simulation tools provided by other researchers or make further consultation with the relevant experts.

To determine the appropriate distance between the trees, experts in mangrove plantation must be involved in the design processes.   

17. Strength and limitations

Once the tsunami wave inputs, the mangrove forest parameters, and the expected wave height reduction is determined this method is straightforward utilized.

The application of the proposed design’ diagram is limited to the field conditions that are agree with the laboratory investigation conditions.

The present technology shall be implemented by assumptions that:

1.    The trees, individually or as a group, have enough resistance against tsunami wave forces. In other words, the trees never collapse under possible range of the design wave height.

2.    The diagrams and equations are empirically derived from laboratory invetigation. No comparison or callibration have been conducted against field data observation.

3.  The investigated tree’s height were not higher than 5m.

Further investigations are necessary to find out solution of the problem that out of present range of application. 

18. Lessons learned through implementation if any


VI. Resources required

19. Facilities and equipments required

Facilities and equipments for designin and planning of mangrove forest dimension:

1. A personal computer or calculator that has capability for doing general calculation, iteration calculation or "trial and error" calculation process. At least has worksheet for database works.

2. Meter-wire or any practical tools for measuring the dimension of the trees to calculate its volume as well as mangrove forest density calculation.

Facilities and equipments for mangrove plantation:

Please refer to the commonly available guidance of mangrove plantation

 

20. Costs, organization, manpower, etc.

Costs: Budget are required for the following action:

1. purchasing personal computer or calculator, tools for measuring trees dimension.

2. labour fee for the mangrove forest measurement activities. 

Organization: The best result will be achieved if cooperation and coordination among stakeholders is conducted.

1. Experts from university or research institution provide their suggestion on the potential of tsunami wave height in the designated area, and also technology of mangrove plantation.

2. Local government or municipality provide support or guarantee on the continuous supply of mangrove seeds; Local government officer, under expert advisory, design and planning the mangrove forest; Local government officers, together with residents group, regularly make inspection and advise on the mangrove maintenance.

3. Local people (community) do cooperation and participate in mangrove planting action as well as its maintenance under coordination of community leader; it will be helpfull if the residents living surounding the area are divided into groups and each group take responsibility for planting and maintaining mangroves.

Manpower: No sophisticated skills are necessary; the most important provision are understanding about the danger of tsunami disaster and the urgency of initiating action of reducing tsunami disaster risk in their own area by self-help and mutual-support.


VII. Message from the proposer if any

21. Message

This study results have not yet been applied to any specific projet. Whereas many of the mangrove plantation projects are implemented not directly for tsunami issues but with more emphasize on environmental enhancements, these two aspects are effective simultaneously.It is believed that, if not direct application, the research output presented herein should be very useful for assessment of the effects of mangrove forests for tsunami disaster reduction.f mangrove forests for tsunami disaster reduction.


VIII. Self evaluation in relation to applicability

22. How do you evaluate the technology/knowledge that you have proposed?

It is a technology/knowledge that is shown to be effective based so far only on scientific experiments in laboratory.

23. Notes on the applicability if any

This technology is derived from laboratory experiment results with many limitations related the laboratory experiment conditions. However, this calculation method is considered reliable for preliminary design of mangrove forest for tsunami protection at coastal area. Mangrove forest habitat is within tidal area with muddy or silty soil. It is usually hard to grow the seeds in the coastal area attacked by severe wave. Semi-permanent protection must be provided until the trees strong enough to stand against wave force (usually until about two years old).


IX. Application examples


X. Other related parallel initiatives if any

Message

Hamzah, Harada, and Imamura(1999), Tohoku University, Japan Harada and Imamura (2000), Tohoku University, Japan Hiraishi and Koike (20002), Port and Airport Research Institute, Japan Widjo and Sakai (2003), Iwate University, Japan Harada & Kawata (2004), Tohoku University, Japan


XI. Remarks for version upgrade

Message

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