ID:  DRH 10  
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. 

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. 62274586239; Fax. 62274542789, email: pakdinar@yahoo.com; dinar@webmail.bppt.go.id.
2. International Center for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), 16 Minamihara, Tsukuba, Ibaraki 3058516, Japan; Phone: +81298796809; Fax: +81298796709; email: dinar55@pwri.go.jp;
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.
mangrove forest, tsunami, disaster reduction, design
Implementation Oriented Technology (IOT)
51. 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
52. Other users: Policy makers , Motivated researchers , Local residents
Tsunami , Storm surge
Human lives , Human networks in local communities , Business and livelihoods , Infrastructure , Buildings , Urban areas , Coastal areas , River banks and fluvial basin , Agricultural lands
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. 62274586239; Fax. 62274542789, email: pakdinar@yahoo.com; dinar@webmail.bppt.go.id.
2. International Center for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), 16 Minamihara, Tsukuba, Ibaraki 3058516, Japan; Phone: +81298796809; Fax: +81298796709; email: dinar55@pwri.go.jp;
JAPAN; INDONESIA;
JAPAN: Southern islands, e.g. Okinawa.
INDONESIA: e.g. Banyuwangi (East Java)
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.
Research On Tsunami Hazard and Its Effects on Indonesia Coastal Region, 20012004
1. Dinar C. Istiyanto, Widjo Kongko, Application of Mangrove Forest for Countermeasure Against Tsunami Disaster, Presented at DRH Content Meeting, EDMNIED, Kobe, 2007.
2. Dinar C. Istiyanto, Implementation of Greenbelt Technique As Coastal Protection Against Tsunami: Experience With EqTAP Implementation Strategy and Expectation on DRHProject, Presented at Asian Disaster Reduction Science and Technology Forum, EDMNIED, Jakarta, 2006.
3. Dinar C. Istiyanto, Utomo, K.S., Suranto, Jauzi, M.Z., The Influence of RhyzoporaShrub on Tsunami Propagation at The Beach, Proceeding of National Seminar on Tsunami, JICACDRC, Indonesia, 2006, pp. 311322 (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, JICACDRC, Indonesia, 2006, pp. 323340. (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, JICACDRC, Indonesia, 2006, pp. 8192. (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 MultiLateral Workshop on The Development of Earthquake and Tsunami Disaster Mitigation Technologies and Their Integration for AsiaPacific Region, Bangkok, Thailand, 2002
Avicena Apiculata Mangrove forest_at the Grajagan Coast_East Java
This technology has been developing to provide engineering tool for planning coastal protection by using mangroveforest 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 mangroveforest density, mangroveforest 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 (B_{L}) 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 – K_{R })]H)/t_{B} (1)
where: d is water depth just at the seaward line of mangrove forest, K_{R} is reflection coefficient of mangrove forest, H is design tsunami wave height just before interacts with mangrove forest and t_{B} is average height of the trees in mangrove forest. See Figure1.
Figure1. Diagram of variables related to the determination of d
The value of d will contain K_{R} variable as K_{R} 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 K_{1} = 0.0125 and K_{2} = 0.05 as in the equation (3) and (4). Linier interpolation shall be conducted for the K value between K_{1} = 0.0125 and K_{2} = 0.05. However, solutions for K < K_{1 }and K > K_{2 }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 Figure2.
Figure2. 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 (B_{L})
B_{L} = 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 B_{L} are then inputted into equation (6), which is the correlation equation of K_{R} and (e.B_{L}) as it is also shown in the graphics of Figure3.
K_{R} = 0.0872 ln(e.B_{L}) + 0.782 (6)
Figure3. Graphics of correlation between K_{R} and (e.B_{L})
Accordingly, an equation with K_{R }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. K_{R} shall be given initial value of 0 £ K_{R }£ 1.
6. Once K_{R} is determined, the definite value of d and e could be calculated.
7. Further, the value of transmission coefficient (K_{T}) and transmitted wave height (H_{T}) shall be calculated by refering to the equation (7), that is related to Figure4, and equation (8) consecutively.
K_{T} = 0.1644 ln(e.B_{L})  0.4601 (7)H_{T} = K_{T}.H_{IR} (8)
where : H_{IR} = [1/(1 – K_{R })] H (9)
Figure4. Graphics of correlation between K_{T} and (e.B_{L})
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 multistakeholder 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.
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.
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. Meterwire 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
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 selfhelp and mutualsupport.
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.
It is a technology/knowledge that is shown to be effective based so far only on scientific experiments in laboratory.
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. Semipermanent protection must be provided until the trees strong enough to stand against wave force (usually until about two years old).
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
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