Optimum insurance contract of flood damage index insurance for rice farmers in Myanmar

Climate change is an underlying cause of many extreme events such as enormous cyclones and erratic torrential rains. These phenomena threaten farmers in coastal regions of Myanmar. Self-insurance through means such as crop diversification is insufficient for sustainable farm management. Weather index insurance (WII) is receiving much attention because of its low management costs. An optimum WII contract for flood damage using rainfall as the index has been proposed for rice farmers in coastal regions. According to the model, an insurance payment demand function is derived by solving the expected utility maximization problem. The utility function of the contract is specified as constant relative risk aversion type. The production function is specified as Cobb–Douglas type. By substituting real average data of rice production of farmers into this function, the optimum insurance payment and premium are obtained. Changes in insurance compensation by payments according to an increase in the price of rice, rainfall, and degree of risk aversion are investigated. Results suggest that if an average farmer pays around 41.5 US dollars per year, then farm management will be optimally stabilized under the flood risk.

     

Factors impacting yields in rain-fed paddies of the lower Mekong River Basin

The Mekong River Basin (MRB) is the biggest basin in Monsoon Asia. About 80% of the agricultural lands, which occupy about 40% of the basin are rain-fed paddy rice area. Therefore, it is assumed that changes in rain-fed paddy rice production affect the total agricultural production to a great degree in the Mekong River Basin. While there are many factors affecting the productivity of rain-fed paddies, such as climate, water use, rice varieties, applications of manure, fertilizer and agro-chemicals, sowing date and other agronomic practices, this paper focuses on the relation between rainfall and yields of rain-fed paddies. Agricultural statistics and rainfall data were collected and analyzed for all 24 provinces in Cambodia for the years 2001 and 2002. Factors such as soil fertility and other natural conditions were removed by comparing the yield and rainfall in one province for different years. Special attention was given to the relation between yields of paddy in the wet season and rainfall, considering factors such as rice varieties, soil fertility, irrigation ratio and the ratio of area damaged by flood, drought, and insect. Although it is not easy to assess those impact factors on yields because they are organically interactive, the following results were obtained: (1) The ratio of high yielding varieties (HYV), soil fertility, and irrigation ratio among many factors that affect yields individually, especially if they are combined, (2) Total rainfall did not have a significant influence on rice yields even for the rain-fed paddies if it was over 700 mm in wet season, and one of the reasons for this would be that there exist supplementary water uses through small ponds and water ponding in local land depressions in and around paddies.     

Analysis of spatial and temporal risk of agricultural loss due to flooding in paddy farms

Evaluating agricultural loss due to flooding is essential for defining an appropriate risk level in flood management projects. This research introduces a method for computing annual damage risk for rice fields with respect to both spatial and temporal pattern of floods, while considering the effect of crop growth stages on the total damage. For finding the spatial pattern of floods, HEC-RAS was employed to derive selected physical parameters of floods of interest and then a physical loss function was used to calculate the unconditional loss over flood prone areas. A time-dependent loss function was introduced for rice to determine the effect of growth on damages derived through the physical loss function. Due to the seasonal nature of agricultural risk, frequency analysis was performed for seasonal discharges for each growth stage of rice. A method was introduced to use the concept of Expected Annual Damage in agricultural fields. A method called “AGEAD” was introduced for evaluating short-term risk for agricultural activities considering their inherent spatial and temporal characteristics. Results showed that damages evaluated by employing AGEAD were completely different from what was obtained by applying a flood of defined return period, i.e. from the results of long-term risk evaluation. While it is common to attribute a unique predicted loss to all flood prone areas, AGEAD application showed that different zones in flooded paddy fields were subjected to different amount of damages from 100 to 0%.     

Development of an innovative conceptual model and a tiered testing strategy for the ecological risk assessment of rice pesticides

Rice paddies constitute a very special agrobiosystem, which for some circumstances, could be considered as a human driven wetland. The complexity of such dynamic systems is a key element for conducting ecological risk assessments, in addition, the proximity of rice paddies to areas of high ecological value must be considered. This paper presents a new conceptual model for conducting ecological risk assessments of pesticides and other agrochemicals in rice, based on a combination of three main elements, the source of the stressor, the exposed environmental compartments and the relevance of the ecological receptors. A tiered testing strategy, starting with the standard requirements for pesticides and moving to specific higher tier studies with three levels of risk refinement is also presented.     

Both environmental factors and countermeasures affect wild boar damage to rice paddies in Boso Peninsula, Japan

Populations of wild boar (Sus scrofa Linnaeus, 1758) and reports of crop damage by them have increased in Japan. In considering strategies for damage control, it is necessary to quantify both the environmental factors and the countermeasures affecting damage. We surveyed damage by wild boar in 1540 rice paddies on the Boso Peninsula. We obtained environmental factors by GIS: distance from forest edges, rivers and settlements; overground openness; and human population density. We recorded the weeding and fencing practices as countermeasures. We constructed cumulative logit models using Bayesian inference to predict damage and assessed the importance of the simultaneous evaluation of environmental factors and countermeasures by deviance information criteria. The best model incorporated both environmental factors and countermeasures, indicating that both are important for predicting damage. It showed that weeding around rice paddies, electric fencing and corrugated iron fencing were effective at reducing damage by wild boar. The risk of damage increased with lower values of distance from forest edges and rivers, overground openness, and human population density, and with higher values of distance from roads. These environmental factors allowed us to identify high-risk cropland where countermeasures could be introduced to reduce damage.     

基于GIS技术的海南岛暴雨洪涝灾害风险区划

选取暴雨洪涝灾害较为严重的海南省为研究对象,综合考虑致灾因子危险性、孕灾环境敏感性、承灾体易损性和防灾减灾能力等4因子的综合作用,将暴雨洪涝灾害风险性评价技术和GIS技术相结合,对暴雨洪涝灾害风险程度进行评价和等级划分,并绘制海南岛暴雨洪涝灾害风险区划图。研究结果表明:海南岛暴雨洪涝灾害风险是由中部地区向四周沿海地区逐渐增大。     

Spray drift: impact of requirements to protect the environment

Spray drift studies in the US have evaluated the effects of application, meteorological and tank mix variables on spray drift. The data have been incorporated into models to predict drift from aerial applications, and to evaluate worst-case drift from ground rig (boom) and orchard airblast applications. An atomisation model has also been developed to predict droplet size for applications of tank mixes with user-defined or reasonable worst-case physical properties through a wide range of hydraulic nozzles applicable to aerial applications. The database and models help provide the exposure risk input to risk assessments for developing appropriate labelling based on exposure and toxicity risk to non-target sensitive areas. This needs to be balanced with allowing crop protection using careful risk/benefit assessments. Buffers or no spray zones may be based on spray quality, release height and other variables such as wind speed where necessary for protecting specific sensitive areas. The impact of protection measures aimed at minimising the incidence and impact of spray drift is discussed in the present paper.     

Systematic assessment of flood mitigation in a tank irrigated paddy fields area

Flood mitigation in irrigation tanks and paddy fields is their favorable aspect though its practical effect is not known very well. A dynamic and systematic approach is presented to assess flood mitigation in a tank irrigated paddy fields area in the worst case where no static buffer function is expected. Based on the linear control theory, transfer function models for runoff process in catchments are identified. Hydraulic models are developed to represent flood dynamics in irrigation tanks, paddy fields, and drainage channels. These models are integrated as an ordinary differential equations system. Then, using the perturbed linear system, flood mitigation in each component of the system is examined in terms of frequency response. An application example demonstrates that a tank irrigated paddy fields area has a significant flood mitigation effect as a low-pass filter. This method has the advantage of assessing flood mitigation even in the case of an increase in the total runoff ratio.     

Traditional ‘maavee’ rice production in Sri Lanka: environmental,economic and social pressures revealed through stakeholder interviews

The Nilwala Ganga Basin of Sri Lanka includes important natural wetlands that are habitat for vulnerable animal and plant species. Flood protection and intensive rice production in the Basin have resulted in degraded acid soils and declining rice yields. However, traditional ‘maavee’ rice production outside the flood protection scheme has continued to generate a high-value rice product. This study reports on interviews conducted with farmers and other stakeholders to document the production practices and the potential environmental and economic benefits associated with maavee rice paddies. The maavee production system has prevailed for at least several decades. Farmers apply no chemicals to their paddies, relying instead on alluvial deposits as a source of nutrients, and on the natural pest and disease resistance of their traditional varieties. The maavee rice product can attain three times the selling price of rice from conventional farms making it more economically viable than conventional rice production. However, much of maavee production is for home consumption and the system is threatened by increasing labour costs, an ageing farming population and pressures to increase rice yields. Non-invasive production practices and the proximity of maavee paddies to regenerating wetlands in the Kirala Kele Sanctuary suggest that traditional paddies may constitute an important habitat for vulnerable wildlife; however, maavee farmers also perceive wetland birds as potentially damaging to rice. Based on a SWOT (strengths, weaknesses, opportunities and threats) analysis, we make recommendations for future research needs and potential management actions to safeguard the environmental and economic sustainability of the maavee system.     

Shelter effect evaluation of the willow works bank protection method: a case study for Beinan River Reach 2009 Typhoon Morakot event

Beinan River is one of the rivers with perfect ecology and full of culture values in Taiwan. It is also the habitat of many freshwater fish species. Besides, the local agricultural crops are famous for exports due to its natural environment, too. Therefore, for these reasons, the hydraulic associations set a series of ecological constructions for waterfowl and fish species around the agricultural water intake areas. For instance, the river bank protection designs the willow works and the fascine mattress by the 8th River Management Bureau for ecological function and hydraulic protection in flood season. In this study, the concept and the methodology of the fish protection habitat predicted model is revealed. Beside the simulated hydraulic models, the indoor experiments of the willow works were conducted to gain the roughness. The hydraulic methods by one- and two-dimensional are used for simulation in flood season (2009 Typhoon Morakot event) to bring up the habitat protection locations. The experimental results showed that for the Manning’s n of the willow works is between 0.1322 and 0.1333 which corresponding height to the real field is about 144–176 cm. Therefore, it provided the revetment roughness data during the shelter effect evaluation. From the velocity distribution, it proves that the vegetated revetment can reduce the flow velocity. Fulfilling previous two main steps in experiment and model calibration, the shelter effect is made good going on discussion. Most of references indicated that the vegetated revetment provided suitable and excellent habitat condition, but rare of them provided the proof in data. This study presents that the WUA is 34,939.94 m² and PUA is 1.53% at the highest discharge of Typhoon Morakot. The whole protection concepts, simulation methods, and results can be utilized for future plan and design of river engineering.     

Experiential relationship between the farming rate of riverside land and flood concentration time factor

In order to prove a reduction function concerning flood damage according to land use, we have to compare evaluation indices, such as flood concentration times. These can be derived from the calculation of the outflows from two basins where rainfall, geology, geographical conditions, etc. are the same and only the land use is different. However, it is very difficult to obtain comparable data from large basins under the above mentioned conditions. An elaborate observation for a long period is required to obtain such data. In this paper, we aim to establish a calculation process that offers consideration factors from a viewpoint that is different from a conventional research where elaborate observation is essential. Therefore, first we use easily obtainable data of many basins, such as the information on the Internet, or data from official documents or the like, which are difficult to deal with in hydrology. Then, we obtain several evaluation indices, which are coefficients close to the flood concentration times in this paper, on each basin in which various kinds of land uses are mixed. We then perform the statistical analysis with a land use ratio. In order to use various data on several basins, we evaluate the difference in the land use ratio in the basin by using of a length of a riverside instead of an area in the basin. Moreover, since a river-mouth is at the end of the riverside and a water stage observation point is not at the river-mouth, an error arises. Although there are several problems in accuracy as mentioned above, the evaluation of the reduction function concerning the flood damage according to land use will be feasible, automatically and efficiently, if the calculation process is established.     

Features of the AFFRC model for evaluating the relationship between the water cycle and rice production

This paper introduces the Agriculture, Forestry and Fisheries Research Council of Japan (AFFRC) model, an integrated model that predicts future rice production in the Mekong River basin by taking into account the effect of global warming on both the water cycle and the rice economy. The model focuses especially on the water balance of paddy fields for different farmland water use systems. We defined six categories of irrigated paddies and three categories of rain-fed paddies on the basis of their systems of water usage. We included a process-based model to predict future rice production, accounting for daily changes in available water resources such as precipitation. Many models of crop production treat rice in the same way as other crops; the particular characteristics of rice farming are considered in more detail in our model. Our results show that it is possible to estimate future rice production in the Mekong River basin by taking into account changes in available water, and to model the resultant effects on the grain market.     

Combining rainfall–runoff and hydrodynamic models for simulating flow under the impact of climate change to the lower Sai Gon-Dong Nai River basin

This study presented simulation results of runoff discharge combining the Mike NAM and Mike SHE models for lower Sai Gon-Dong Nai River basin (SG-DNRB). Sai Gon-Dong Nai River basin is Vietnam’s largest population center and main industrial area in Ho Chi Minh City. In recent years, the area faces flooding problems because of heavy rainfalls and high tides, as part of the impacts of climate change and sea level rise. The lower of SG-DNRB was selected as a case study to highlight the necessity to investigate combination of the rainfall–runoff model and the hydrodynamic model for long-term strategies to resource water in the future. The models were calibrated using water level and runoff discharge data during low and flood seasons in 2014. The calibrated results showed satisfactory coefficients (NASH index, R² up to 0.70 and RMSE is smaller than 0.20). The results confirmed that the combination of Mike NAM and Mike SHE models is well suitable to simulate runoff discharge in the lower SG-DNRB. Combination of the models can be considered a useful tool to help professional agency operator water resources management projects in other areas in the context of climate change and sea level rise.     

Taxocoenosis and distribution of nektonic fauna in the rice fields of Kashmir (J and K) India

Present study attempts to identify the taxocoenosis and distribution of nektonic fauna harbouring the rice field ecosystems of Kashmir. The main objective of the study was to provide an overview of the nektonic community composition and physicochemical characteristics of flood waters. 6 sites were selected in Kupwara, Bandipora, Budgam, Srinagar, Pulwama and Anantnag districts of valley Kashmir. A total of 26 taxa belonging to 13 different orders were reported during the study which commenced through 2 consecutive crop cycles. The taxocoenosis was dominated by Coleoptera (10 taxa) followed by Hemiptera (3 taxa), Diptera (2 taxa), Diplostraca (2 taxa), Acarina, Anostraca, Anura, Amphipoda, Basommatophora, Cypriniformes, Cyprinodontiformes, Odonata and Pulmonata (1 taxa each). Diversity was calculated using Simpsons Index (D), Simpsons Index of Diversity (1-D), Simpsons Reciprocal Index (1/D), Shannon-Weiner Index (H'), Margalef Richness Index (d) and Evenness Index (e). Kupwara (34 degrees 02'N; 74 degrees 16'E) formed the most diverse site registering a total of 2384 individuals belonging to 24 taxa. A perusal of the primary data related to the physicochemical attributes of flood waters exhibited that average water temperature varied between 19-30 degrees C, average air temperature varied between 21 and 33 degrees C. pH depicted a variation between 6.0 and 9.0, Dissolved Oxygen varied between a minimum of 1.0 mg L(-1) and a maximum of 10 mg L(-1). Free CO2 ranged between 0 mg L(-1) and 6.1 mg(-1). The results pressed the need for recognizing and preserving rice fields as potential habitats for organisms that have successfully adapted to the highly manipulated and eutrophic conditions of rice paddies.     

Estimation of flood risk index considering the regional flood characteristics: a case of South Korea

Global warming is increasing the variability of climate change and intensifying hydrologic cycle components including precipitation, infiltration, evapotranspiration, and runoff. These changes increase the chance of more severe and frequent natural conditions, and limit ecosystem function and human activities. Adaptation to climate change requires assessment of the potential disaster risk. The objectives of this study were to estimate the flood risk index (FRI) considering regional flood characteristics at the national level and to prioritize the factors affecting flood risk through principal component analysis. FRI was estimated based on the Delphi survey results from 50 water resources experts in South Korea. The potential risk analysis was conducted for 229 local governments in South Korea. The results showed that natural and social factors were more influential flood risk factors to South Korea than administrative and economic and facility factors. Specifically, natural, social, administrative and economic, and facility factors were, respectively, highest at Jindo-Gun in Jennam-Do, Gumi-Si in Kyongsanbuk-Do, Dong-Gu in Incheon-Si, and Suwon-Si, Kyonggi-Do. Overall, the highest FRI is shown in Anyang-Si, Kyongggi-Do. The spatial distribution of the FRI was high in the southeastern coastal region and basins of the two biggest rivers in South Korea, and normalized flood frequency followed spatial patterns similar to FRIs. This study provided information on the relative flood risk index among administrative units for investment prioritization in flood risk management. In this regard, the suggested FRI is expected to significantly contribute to methodical and economic improvements in budget allocations for flood risk management.     

Spatial optimization procedure for land-use arrangement in a community based on a human comfort perspective

The arrangement of land use substantially affects outdoor human comfort. The purposes of this study were to develop a spatial optimization procedure that involves combining simulated annealing algorithm with a microclimate model (ENVI-met) and to identify the relationship between the spatial pattern of the major cooling source and human comfort. The procedure is an assessment tool for appropriately designing living space on a community scale. The physiological equivalent temperature (PET) was used as the index of human comfort, and the objective of optimization was to minimize the difference in the PET to 23 °C within the study area. Four types of land use, namely buildings, paddies, parks, and ponds, were considered. Given the types of land use and the land areas, the procedure is used to determine the optimal layout that provides the most comfortable environment. The results revealed that the optimal design effectively improved the homogeneity of human comfort quantitatively and spatially in summer. Human comfort in the entire area was improved when the prevailing wind first passes through cooling sources, such as the paddies, and the walkways are easier to cool when the cooling sources are located nearby. The results of the spatial optimization procedure can further be applied to determine the relationship between the spatial pattern of land use and human comfort, and the relationship can be used as a reference for future research on community design.     

Competitive assembly of South Pacific invasive ant communities

Background  

The relative importance of chance and determinism in structuring ecological communities has been debated for nearly a century. Evidence for determinism or assembly rules is often evaluated with null models that randomize the occurrence of species in particular locales. However, analyses of the presence or absence of species ignores the potential influence of species abundances, which have long been considered of major importance on community structure. Here, we test for community assembly rules in ant communities on small islands of the Tokelau archipelago using both presence-absence and abundance data. We conducted three sets of analyses on two spatial scales using three years of sampling data from 39 plots on 11 islands.     

Plant diversity and composition of rice field bunds in Southeast Asia

Which plant species can be found on rice field bunds and what are the prevailing life forms? Which plant communities occur and what are the main environmental drivers and phytogeographic patterns shaping these communities? How do species diversity and composition differ between bunds and paddies? To answer these questions, 133 vegetation relevés using the Braun-Blanquet method were collected in lowlands and uplands of Vietnam and the Philippines between 2012 and 2015. Soil samples were collected and farmers were interviewed. Properties of soil, climate, and geography were assessed, further structural parameters, landscape heterogeneity, seasonality, management and intensity of cultivation. Hierarchical UPGMA cluster analysis and NMDS ordinations were performed to visualize variation in plant community composition and the determinants. We found 302 vascular plant species, of which 94 species are red listed by the IUCN (under category “Least concern”). Therophytes and helophytes are the prevailing life forms. Six clusters of plant communities were classified, and temperature, soil acidity, land use intensity and nutrient availability were identified (according to relevance) as explanatory variables. Bunds revealed higher species richness than paddies and bunds in mountain areas were more species-rich than those in the lowlands. We conclude that the composition of bund communities provides valuable information on environmental and biogeographical conditions of the local rice landscapes, and that it is probably the best applicable and most reliable indicator of management intensity.     

Enhancing multi-functionality of agriculture through rainwater harvesting system

The multi-functionality of agriculture was studied from June to December 2005 in an upland community in Central Luzon, Philippines, by looking across the entire basin of two small water impounding systems or SWIP (Maasin and Buted II). Several sub-studies were undertaken, namely (a) the role of dominant vegetative cover on the rate of surface runoff and erosion; (b) rainfall–runoff analysis in a sub-watershed (i.e., through runoff experimental plot) and within the main watershed (i.e., reservoir inflow analysis); and (c) the environmental functions of agriculture across the entire watershed. The results indicated that about 85% (i.e., throughfall) of rainfall could reach the ground as vegetations intercept the rest. The runoff experimental plot covering a sub-watershed revealed a good correlation between throughfall and runoff. On the other hand, monitoring of reservoir inflows through which surface runoff was measured indicated similar behavior. Integrating the result of runoff experimental plot studies and reservoir inflow analysis resulted to a rainfall–runoff relation which can be applied in the development of rainwater harvesting scheme. The result also showed the dominance of surface runoff as the main component of reservoir inflow, confirming the soil and water conservation, and flood prevention functions of the system. Flood analysis conducted in both SWIP confirmed their flood prevention function by reducing flood peak discharge. The difference between with and without the reservoir was also highlighted in the process. In the paddy field, a 5-cm water depth was consistently maintained, contributing in retaining about 0.543 and 0.272 MCM of rainwater in Maasin and Buted II, respectively. The value of fostering groundwater recharge throughout the entire system was almost equivalent to the value of flood prevention function. Moreover, SWIP also trapped sediments, thereby preventing offsite impact downstream and in surrounding areas.This paper is part of the progress report of the project “Multi-functionality of Agriculture in Selected Sites in the Philippines” presented in the 6th Meeting of the Working Group for the ASEAN-Japan Project on Multi-functionality of Agriculture in ASEAN Countries.     

Ciguatera Fish Poisoning in East Asia and Southeast Asia

In the coastal countries of East Asia and Southeast Asia, ciguatera should be common because of the extensive tropical and subtropical coral reefs along the coasts and in the neighboring seas with ciguatoxic fishes. An extensive search of journal databases, the Internet and the government websites was performed to identify all reports of ciguatera from the regions. Based on the official data and large published case series, the incidence of ciguatera was higher in the coastal cities (Hong Kong, Foshan, Zhongshan) of southern China than in Japan (Okinawa Prefecture). In Singapore, ciguatera appeared to be almost unknown. In other countries, only isolated cases or small case series were reported, but under-reporting was assumed to be common. Ciguatera may cause severe acute illness and prolonged neurological symptoms. Ciguatera represents an important public health issue for endemic regions, with significant socio-economic impact. Coordinated strategies to improve risk assessment, risk management and risk communication are required. The systematic collection of accurate data on the incidence and epidemiology of ciguatera should enable better assessment and management of its risk. Much more work needs to be done to define the size threshold for important coral reef fish species from different regions, above which the risk of ciguatera significantly increases.