Morakot Research Articles

Cultural issues in post-disaster reconstruction: the case of Typhoon Morakot in Taiwan.

Most members of Taiwan's indigenous communities live in areas that are prone to natural disasters. Yet, due to their marginalised cultural, economic and political status, each time such calamities strike, any assistance they receive is usually provided without considering their actual needs. The areas hardest hit by Typhoon Morakot in August 2009 were the indigenous villages in the southern and eastern parts of the island. After the initial emergency relief efforts had been completed, there remained the highly challenging task of reconstruction and the resettlement of those who lost their homes and livelihoods. This paper examines the cultural conflicts that arose during the reconstruction process, with special emphasis on the participation of Taiwan's indigenous communities and their capacity for resilience. It was found that community participation and identification are key issues in effective disaster governance.

Study of 24-hour probable maximum precipitation and associated landslide hazards for Hong Kong

Probable Maximum Precipitation (PMP), which is an extreme rainfall level widely used for dam and reservoir engineering, has been taken as a practical reference for expressing extreme rainfall events for formulating landslide scenarios in Hong Kong’s landslide emergency preparedness. Landslide hazards had been assessed based on scenarios corresponding to 90% of the 24-hour PMP, which was estimated by Hong Kong Observatory in 1999. The results indicated that more than 3,000 landslides affecting buildings or roads would occur if Hong Kong Island is struck by a storm of this level of rainfall. An updating of the 24-hour PMP has recently been carried out using the method of storm transposition. In this method, the major storm associated with Typhoon Morakot, which lashed Taiwan seriously in 2009, was targeted to be transposed to Hong Kong. Based on the Step Duration Orographic Intensification Factor (SDOIF) Method, storm separation technique was applied to separate the convergence component from the orographic component of the major storm and the convergence component was transposed and then combined with the local orographic factors in Hong Kong for PMP estimate. This paper will present the method adopted in the transposition and discuss the results for the updating of the PMP estimate. The assessment of the landslide scenarios corresponding to the updated PMP will also be discussed.

Landslide dam formation susceptibility analysis based on geomorphic features

Global climate change has increased the frequency of abnormally high rainfall; such high rainfall events in recent years have occurred in the mountainous areas of Taiwan. This study identifies historical earthquake- and typhoon-induced landslide dam formations in Taiwan along with the geomorphic characteristics of the landslides. Two separate groups of landslides are examined which are classified as those that were dammed by river water and those that were not. Our methodology applies spatial analysis using geographic information system (GIS) and models the geomorphic features with 20 × 20 m digital terrain mapping. The Spot 6 satellite images after Typhoon Morakot were used for an interpretation of the landslide areas. The multivariate statistical analysis is also used to find which major factors contribute to the formation of a landslide dam. The objective is to identify the possible locations of landslide dams by the geomorphic features of landslide-prone slopes. The selected nine geomorphic features include landslide area, slope, aspect, length, width, elevation change, runout distance, average landslide elevation, and river width. Our four geomorphic indexes include stream power, form factor, topographic wetness, and elevation–relief ratio. The features of the 28 river-damming landslides and of the 59 non-damming landslides are used for multivariate statistical analysis by Fisher discriminant analysis and logistic regression analysis. The principal component analysis screened out eleven major geomorphic features for landslide area, slope, aspect, elevation change, length, width, runout distance, average elevation, form factor, river width, stream power, and topography wetness. Results show that the correctness by Fisher discriminant analysis was 68.0 % and was 70.8 % by logistic regression analysis. This study suggests that using logistic regression analysis as the assessment model for identifying the potential location of a landslide dam is beneficial. Landslide threshold equations applying the geomorphic features of slope angle, angle of landslide elevation change, and river width (H L/W R) to identify the potential formation of natural dams are proposed for analysis. Disaster prevention and mitigation measures are enhanced when the locations of potential landslide dams are identified; further, in order to benefit such measures, dam volume estimates responsible for breaches are key.

Rainfall-Runoff Prediction Using Dynamic Typhoon Information and Surface Weather Characteristic Considering Monsoon Effects

In meteorology and engineering, the prediction of quantitative precipitation and streamflow during typhoon events is a vital research topic. In Southern Taiwan, typhoons often occur in the summer. The interaction between the typhoon circulation and southwesterly monsoon flow frequently transports abundant moisture into Southern Taiwan leading to the substantial pouring rains. This study proposes a rainfall-runoff prediction methodology for addressing the complicated inflow forecasts of southwest monsoon rainfall during typhoons in the upper Tsengwen River in Southern Taiwan. This paper is novel in that it incorporates various data types (reservoir inflows, watershed rainfalls, typhoon information, and ground-weather characteristics) that were applied as model inputs. The most frequently used support vector regressions were employed to construct the rainfall-runoff models on the basis of three designed data combination scenarios. Typhoons Kalmaegi (2008), Fung-wong (2008), Jangmi (2008), and Morakot (2009) were used as validation typhoons. The model cases, involving lead times of 1 h to 6 h, were evaluated. Six performance criteria were used in the three scenarios to highlight the scenario capable of identifying the optimal performance level. In addition, this study compared the error rates between accumulation observations and accumulation predictions. The results showed that Scenario 3, which considered typhoon information and ground-weather characteristics simultaneously, had superior watershed rainfall and runoff predictions to those of the other scenarios. Thus, this study demonstrated the feasibility of using the proposed methodology to increase the accuracy of rainfall-runoff predictions.

Vulnerability, resilience, and the adaptive cycle in a crisis-prone tourism community

ABSTRACTIn light of the growing impact of natural disasters around the globe, the development of sustainable, community-based tourism today requires an understanding of the vulnerability, resilience, and adaptive capacity of communities to manage sudden change. These theories have developed differently over time, and each offers distinct insights and limitations. An analysis of the implications of these three perspectives provides an integrated framework of the time process, structure-agency, and essential meaning that enables an understanding of how communities respond to disasters through three dimensions: (1) sensitivity--stability, (2) maladaptive capacity-recovery, and (3) transformation. In addition, using the theories of vulnerability and resilience along with the adaptive cycle model of change over time, we can reinterpret the four phases of growth, conservation, release, and reorganization as a more logical way of thinking through fluctuation and comprehensiveness. The Shanmei community in Taiwan, following Typhoon Morakot in 2009, provides a case in point. We conducted qualitative research and employed literature reviews, an environmental investigation, observations, and in-depth interviews to gather data and information. The findings indicate that the perspective of exposure in the theory of vulnerability should consider the multiple spatial scale and distinguish socio-economic stability, recovery through social networks, and transformation as sustainable elements of this community-based tourism using the integrated framework of vulnerability and resilience. In the adaptive cycle model, the integration of vulnerability and resilience theory shows that in a tourism landscape in a mountainous area, the cycle between destruction and reproduction becomes more rapid.

Modeling Typhoon‐Induced Alterations on River Sediment Transport and Turbidity Based on Dynamic Landslide Inventories: Gaoping River Basin, Taiwan

This study examines the impacts of storm‐triggered landslides on downstream sediment and turbidity responses in the Gaoping River Basin, Taiwan using the Soil and Water Assessment Tool (SWAT). Attention is given to analyzing the increased and altered baseline of suspended sediment load and turbidity after the disturbances caused by the rainfall and landslides associated with Typhoon Morakot in 2009. SWAT parameters were calibrated by the observed hydrometric data from 1999 to 2003 using the log‐scale root‐mean‐square error (log‐RMSE) and Nash‐Sutcliffe Model Efficiency. Both parameter sets were applied for the simulation of suspended sediment yield and turbidity with annual updated landslide inventories for the period 2004–2012. The landslide updating mirrors the physical land‐cover changes and has slightly improved the model performance, yet landslides alone cannot explain the difference between Morakot‐induced and SWAT‐simulated sediment discharge. The set of parameters calibrated by log‐RMSE can better approximate the increased baseline and typhoon induced alterations. The results show alterations in sediment erosion and transport: (1) drastically increased the turbidity baseline and occurrence of high‐turbidity; (2) altered coefficient and exponent values of the sediment rating curve; and (3) altered relationship between rainfall and induced turbidity during major rainfall events. The research in this study provides an improved modeling approach to typhoon‐induced alterations on river sediment loads and turbidity.

Reassembling Solar Farms, Reassembling the Social: A Case Study of Ping-Tung County in Southern Taiwan

In this article, I seek to offer a story of how an industrialized East Asian country, Taiwan, transformed itself into not only a producer of solar photovoltaic (PV) products but also a user of such technology. By highlighting redesignable artifacts, sociotechnical rearrangement, and local government translators, I apply actor-network theory to describe and analyze the emerging phenomenon of solar farms in Ping-Tung County in southern Taiwan, which simultaneously involves human and nonhuman actors. During the postdisaster reconstruction after Typhoon Morakot, 23.481 MW of solar panels were installed in the flood-damaged orchards and fish ponds in central Ping-Tung. The sites of the solar farms are neither the rooftops of buildings nor industrial wastelands. Solar PV products transferred from Western countries to Taiwan are called “redesignable artifacts.” If a certain technological artifact can be redesigned in a certain society, there are a certain number of people who are familiar with such technology and are skilled in its use. In other words, a variety of industrial local knowledge and technological supporting networks are deployed evenly and densely in Taiwan. Artifacts that are “black-boxed” by solar PV manufacturers can have some agency to make new sociotechnical networks, but only through certain “translators.” In my case study, the most important translators are the magistrate of the county government and his green energy team. By connecting local knowledge with expert knowledge and by connecting sites of agriculture and aquaculture with PV equipment workshops, these translators make heterogeneous human and nonhuman actors work in the same sociotechnical network, a symbiotic network of PV technologies, agriculture, and aquaculture. With the black-boxed objects, the solar PV products, in hand, these translators can break up the traditional connections between local farmers and their lands and make new connections among solar PV manufacturers, local landlords, and their lands. In the process of connecting heterogeneous sites, every group redefines its interests and begins an agenda of group formation. Every actor is displaced and seeks a “sociotechnical rearrangement” with other actors.

Effects of surface flux parameterization on the numerically simulated intensity and structure of Typhoon Morakot (2009)

The effects of surface flux parameterizations on tropical cyclone (TC) intensity and structure are investigated using the Advanced Research Weather Research and Forecasting (WRF-ARW) modeling system with high-resolution simulations of Typhoon Morakot (2009). Numerical experiments are designed to simulate Typhoon Morakot (2009) with different formulations of surface exchange coefficients for enthalpy (CK) and momentum (CD) transfers, including those from recent observational studies based on in situ aircraft data collected in Atlantic hurricanes. The results show that the simulated intensity and structure are sensitive to CK and CD, but the simulated track is not. Consistent with previous studies, the simulated storm intensity is found to be more sensitive to the ratio of CK/CD than to CK or CD alone. The pressure–wind relationship is also found to be influenced by the exchange coefficients, consistent with recent numerical studies. This paper emphasizes the importance of CD and CK on TC structure simulations. The results suggest that CD and CK have a large impact on surface wind and flux distributions, boundary layer heights, the warm core, and precipitation. Compared to available observations, the experiment with observed CD and CK generally simulated better intensity and structure than the other experiments, especially over the ocean. The reasons for the structural differences among the experiments with different CD and CK setups are discussed in the context of TC dynamics and thermodynamics.

Landslide and debris flow initiated characteristics after typhoon Morakot in Taiwan

Typhoon Morakot brought extreme rainfall and initiated numerous landslides and debris flows in southern Taiwan in August of 2009. The purpose of this study is to identify the extreme rainfall-induced landslide frequency-area distribution in the Laonong River Basin in southern Taiwan and debris flow-initiated conditions under rainfall. Results of the analysis show that debris flows were initiated under high cumulative rainfall and long rainfall duration or high rainfall intensity. The relationship of mean rainfall intensity and duration threshold could reflect debris flow initiation characteristics under high rainfall intensity in short rainfall duration conditions. The relationship of cumulative rainfall and duration threshold could reflect debris flow initiation characteristics under high cumulative rainfall in long rainfall duration. Defining rainfall events by estimating rainfall parameters with different methodologies could reveal variations among intermittent rainfall events for the benefit of issuing debris flow warnings. The exponent of landslide frequency-area distribution induced by Typhoon Morakot is lower than that induced by the Chi-Chi earthquake. The lower exponent of landslide frequency-area distribution can be attributed to the transportation and deposition areas of debris flow that are included in the landslide area. Climate change induced high rainfall intensity and long duration of precipitation, for example, Typhoon Morakot brought increased frequency of debris flow and created difficulty in issuing warnings from rainfall monitoring.

A numerical study of convection in rainbands of Typhoon Morakot (2009) with extreme rainfall: roles of pressure perturbations with low-level wind maxima

Abstract. This paper investigates the formation and evolution of deep convection inside the east–west oriented rainbands associated with a low-level jet (LLJ) in Typhoon Morakot (2009). With the typhoon center to the northwest of Taiwan, the westerly LLJ occurred as a result from the interaction of typhoon circulation with the southwest monsoon flow, which supplied the water vapor for the extreme rainfall (of ~ 1000 mm) over southwestern Taiwan. The Cloud-Resolving Storm Simulator with 1 km grid spacing was used to simulate the event, and it successfully reproduced the slow-moving rainbands, the embedded cells, and the dynamics of merger and back-building (BB) on 8 August as observed. Our model results suggest that the intense convection interacted strongly with the westerly LLJ that provided reversed vertical wind shear below and above the jet core. Inside mature cells, significant dynamical pressure perturbations (p'd) are induced with positive (negative) p'd at the western (eastern) flank of the updraft near the surface and a reversed pattern aloft (> 2 km). This configuration produced an upward-directed pressure gradient force (PGF) to the rear side and favors new development to the west, which further leads to cell merging as the mature cells slowdown in eastward propagation. The strong updrafts also acted to elevate the jet and enhance the local vertical wind shear at the rear flank. Additional analysis reveals that the upward PGF there is resulted mainly by the shearing effect but also by the extension of upward acceleration at low levels. In the horizontal, the upstream-directed PGF induced by the rear-side positive p'd near the surface is much smaller, but can provide additional convergence for BB development upstream. Finally, the cold-pool mechanism for BB appears to be not important in the Morakot case, as the conditions for strong evaporation in downdrafts do not exist.

Evolution of the large landslide induced by Typhoon Morakot: A case study in the Butangbunasi River, southern Taiwan using the discrete element method

In 2009, Typhoon Morakot delivered high intensity rainfall and triggered many sites of large landslide, which projected areas were larger than 10,000m2 from the satellite image, especially in southern Taiwan. According to DTM analysis, the material volume of the large landslide in Butangbunasi River was more than four times larger than that of the nearly famous landslide disaster in Hsiaolin village. Nevertheless, the different movement of these two large landslides led to different disaster impacts. Based on literatures and field works, the large Hsiaolin landslide was a catastrophic landslide, which had high velocity and less energy loss in the kinematic process. The source area of the large landslide in the Butangbunasi River, on the other hand, was composed of several landslide events, and the kinetic energy dissipated when the landslide materials attained to riverbed in sequence. In this study, we divided the Butangbunasi River large landslide into five slope units, namely A, B, C, D and E landslide events, to recognize the mechanism of the large landslide, and the simulation by using the Particle Flow Code 3D (PFC3D), which is based on the discrete element method, provided the kinematic process of the large landslide in the Butangbunasi River. It is noticed that most of the initial energy dissipated during the movement which the fist happening landslide event counteracted the crash of the follow-up events, and the residual energy gradually declined by the collision interaction of landslide blocks until the end of the large landslide. The result helps to reconstruct the evolution of the large landslide from small-scale landslide events and contributes to predict the affected region of the disaster. It also reveals that even though the impact of the large landslide is reduced by sequent small-scale landslide events, there still remain secondary disasters, such as landslide dam, which show a high potential risk in the river valley and midstream.

Landslide seismic magnitude

Landslides have become one of the most deadly natural disasters on earth, not only due to a significant increase in extreme climate change caused by global warming, but also rapid economic development in topographic relief areas. How to detect landslides using a real-time system has become an important question for reducing possible landslide impacts on human society. However, traditional detection of landslides, either through direct surveys in the field or remote sensing images obtained via aircraft or satellites, is highly time consuming. Here we analyze very long period seismic signals (20–50 s) generated by large landslides such as Typhoon Morakot, which passed though Taiwan in August 2009. In addition to successfully locating 109 large landslides, we define landslide seismic magnitude based on an empirical formula: Lm=log⁡(A)+0.55log⁡(Δ)+2.44, where A is the maximum displacement (μm) recorded at one seismic station and Δ is its distance (km) from the landslide. We conclude that both the location and seismic magnitude of large landslides can be rapidly estimated from broadband seismic networks for both academic and applied purposes, similar to earthquake monitoring. We suggest a real-time algorithm be set up for routine monitoring of landslides in places where they pose a frequent threat.

Warning Model for Shallow Landslides Induced by Extreme Rainfall

In this study, the geophysical properties of the landslide-prone catchment of the Gaoping River in Taiwan were investigated using zones based on landslide history in conjunction with landslide analysis using a deterministic approach based on the TRIGRS (Transient Rainfall Infiltration and Grid-based Regional Slope-Stability) model. Typhoon Morakot in 2009 was selected as a simulation scenario to calibrate the combination of geophysical parameters in each zone before analyzing changes in the factor of safety (FS). Considering the amount of response time required for typhoons, suitable FS thresholds for landslide warnings are proposed for each town in the catchment area. Typhoon Fanapi of 2010 was used as a test scenario to verify the applicability of the FS as well as the efficacy of the cumulative rainfall thresholds derived in this study. Finally, the amount of response time provided by the FS thresholds in cases of yellow and red alerts was determined. All five of the landslide events reported by the Soil and Water Conservation Bureau were listed among the unstable sites identified in the proposed model, thereby demonstrating its effectiveness and accuracy in determining unstable areas and areas that require evacuation. These cumulative rainfall thresholds provide a valuable reference to guide disaster prevention authorities in the issuance of yellow and red alerts with the ability to reduce losses and save lives.

The Impact of Typhoon Morakot on Heavy Metals of Dapeng Bay and Pollution from Neighboring Rivers

This study demonstrates that prior to Typhoon Morakot, the index of heavy metals such as Cd, Pb, and Cr was above moderate pollution levels in Dapeng Bay and the three neighboring rivers. During January 2007, the content of Zn metal in Dapeng Bay and Tungkang River was also above moderate pollution levels, while after the Typhoon Morakot event, all metals were at levels below the criteria for low pollution. This work has demonstrated that the samples collected from Dapeng Bay and the three neighboring river systems displayed individual crowd–distribution phenomena, indicating variability between the heavy metal content of sediments collected from Dapeng Bay and the three neighboring rivers. Understanding the spatial and temporal variability of heavy metal pollutants in the sediments of Dapeng Bay, along with pollution sources from three neighboring rivers, provides useful information in the fields of disaster management, habitat recovery, operative management, as well as ecotourism specification.

Evidence for stable Sr isotope fractionation by silicate weathering in a small sedimentary watershed in southwestern Taiwan

Radiogenic Sr isotopes (87Sr/86Sr) are robust for provenance identification in hydrology, affected mainly by the age of background lithologies and the degree of chemical weathering. However, there is limited knowledge concerning the fractionation mechanism of stable Sr isotopes (88Sr/86Sr) in rivers. In this study, river water was collected on a weekly to monthly basis throughout dry and wet seasons. Furthermore, to study the variations of radiogenic and stable Sr isotopes during intense weathering, a major flooding event (2000mm precipitation in three days, Typhoon Morakot), water was captured within a small drainage catchment system (161km2) along the Hou-ku River in southwestern Taiwan. For a better constraint on the end member compositions, bedload sediments, suspended particles, and several host rocks were sampled for a systematic investigation. The carbonate and silicate phases of these solids were chemically separated. Dissolved major elements indicate that the watersheds were predominated by silicate weathering. Stable Sr isotopes show no significant variation (δ88Sr=0.24–0.31‰) temporally and spatially with an average of 0.28‰. Additionally, all solids showed lower δ88Sr values than the river water while the host rocks had higher δ88Sr values (δ88Sr=0.20–0.26‰) than the residual weathering products (δ88Sr=0.08–0.22‰), indicating preferential leaching of heavy Sr into the hydrosphere and leaving light Sr in the residual solids. Results of laboratory acid leaching experiments reveal that dissolution of high δ88Sr value minerals occurred at an early stage of weathering. The variation of weathering intensity does not alter stable Sr isotopes in silicate weathering dominated river water, which contains higher stable Sr isotopes than the associated sediments. The silicatic sedimentary rocks preferentially released higher stable Sr isotopes into the hydrosphere during chemical weathering, thus leaving lower stable Sr isotopes in the residual solids.

Eye movement desensitization and reprocessing for treating psychological disturbances in Taiwanese adolescents who experienced Typhoon Morakot

In this case–control study, we aimed to assess the intervention effects of four-session eye movement desensitization and reprocessing (EMDR) on reducing the severity of disaster-related anxiety, general anxiety, and depressive symptoms in Taiwanese adolescents who experienced Typhoon Morakot. A total of 83 adolescents with posttraumatic stress disorder related to Typhoon Morakot, major depressive disorder, or current moderate or high suicide risk after experiencing Typhoon Morakot were allocated to a four-session course of EMDR (N = 41) or to treatment as usual (TAU; N = 42). A multivariate analysis of covariance was performed to examine the effects of EMDR in reducing the severity of disaster-related anxiety, general anxiety, and depressive symptoms in adolescents by using preintervention severity values as covariates. The multivariate analysis of covariance results indicated that the EMDR group exhibited significantly lower preintervention severity values of general anxiety and depression than did the TAU group. In addition, the preintervention severity value of disaster-related anxiety in the EMDR group was lower than that in the TAU group (p = 0.05). The results of this study support that EMDR could alleviate general anxiety and depressive symptoms and reduce disaster-related anxiety in adolescents experiencing major traumatic disasters.

Applying Risk Analysis to the Disaster Impact of Extreme Typhoon Events Under Climate Change

Extreme typhoon precipitation events frequently have a socioeconomic impact and result in the loss of human life. Therefore, conducting thorough evaluations of the disaster scale before the occurrence of extreme typhoon precipitation events is beneficial to disaster reduction. This study selects the Tsengwen River basin, Taiwan, the area most severely impacted by typhoon Morakot, as a demonstration area, and adopts dynamical downscaling data to simulate the top ten extreme typhoon precipitation events of the future (from 2069 to 2099) under climate change. The SOBEK model (commercial software) and the Taiwan Typhoon Loss Assessment System (TLAS), established by the National Science and Technology Center of Disaster Reduction (NCDR), are used to evaluate the potential losses resulting from the ten extreme events. The results indicate that the average total loss caused by the ten simulated typhoon events amounts to US$439 million, with agriculture, followed by aquaculture and forestry, suffering the greatest damage. A correlation analysis is also employed to identify key factors that influence loss, including the maximum 6-hour cumulative precipitation, the maximum peak runoff, and the use of the land. Based on these analysis results, this study provides applicable coping strategies that will effectively reduce the impact of future extreme precipitation events in the Tsengwen River basin.

Compound Strategy Forward to Compound Disaster Mitigation: Lessons from Hsiaolin Village, Typhoon Morakot 2009

In 2009, the heavy rainfall induced by Typhoon Morakot hit Hsiaolin Village that caused catastrophic flooding, landslides, landslide dam breakages and debris flows. Such a called “compound disaster” is defined as a disaster in which extensive floods or sediment transports occur simultaneously or consecutively at the catchment area during an event. It challenges current warnings, forecasting and responses to sediment disasters. New concepts and procedure thus are needed to cope with such “compound disasters.” Rainfall hydrographs show downpours of long duration, high intensity, high accumulation and large extent. To better delineate these disasters and provide possible coping strategies, we rebuild the temporal order and spatial distribution of the disaster processes involved. The study suggest correlating individual disaster types with rainfall through simulation. This could clarify the causality between what happened in Hsiaolin Village and related disasters. Our results will strengthen disaster prevention in debris flows and shallow landslides using strateghies that could then be applied to warning systems for deep-seated landslide and landslide dams. The derivative issues and the approach to compound disaster prevention are suggested for future tasks.

Debris as Resources Applied in Wild Creeks Remediation Work

In recent years, especially after typhoon Morakot, extreme torrential rain has resulted in large amounts of landslides in Taiwan. Debris that accumulated downslope blocked the drainage way and induced debris flow very often. The large amount of debris transported to wild creeks downstream may caused elevated riverbeds and channel siltation. All nearby villages and utilities are under this threat. The cleanout work of aggregated debris is of great priority after a disaster. In processing the cleanout work for wildcreek, debris can be treated as useful resources. This is very important in the watershed management and rehabilitation work. In solving the debris blockage problem, cleanout of debris so as to recover the drainage capability of watershed and at the same time, use the earth material to form the protecting measures can meet the carbon reduction requirement. Cleanout of the debris can be used in filling low-lying land in the upstream catchment area. By applying feasible methods to improve engineering properties of the debris can be used to make a variety of protective measures, to resolve the loss of land, roads, damaged buildings and other issues. In planning, the first is to consider the location and the protected object, etc., can be planned establish of embankment, bank protection, slope protection, and berms.

Outdoor activities and depressive symptoms in displaced older adults following natural disaster: community cohesion as mediator and moderator

Objectives: This investigation examined whether community cohesion mediates or moderates the relationship between outdoor activities and depressive symptoms in older adults displaced by Typhoon Morakot in Taiwan.Method: This cross-sectional study included 292 adults aged 65 years or older who were relocated to permanent houses after Typhoon Morakot damaged their homes on 8th August 2009. Multiple regression analysis was applied to test the role of community cohesion on the association between outdoor activities and depressive symptoms.Results: The sample of displaced older adults displayed higher prevalence of depressive symptoms than the average for community dwelling older people in Taiwan. Community cohesion fully mediated the relationship between outdoor activities and depressive symptoms. Community cohesion also moderated the relationship between outdoor activities and depressive symptoms.Conclusion: Community cohesion occupies a key role on the link between outdoor activities and depressive symptoms. Participation in outdoor activities was associated positively with community cohesion, while high community cohesion was related negatively to depressive symptoms. Additionally, the benefit of outdoor activities to fewer depressive symptoms only manifested in older adults with high community cohesion. Programs and services should be designed to enhance community cohesion in order to maximize the benefit of outdoor activities to the mental health of displaced older adults after natural disasters.