Tropical Monsoon Areas Research Articles

Biodegradation of domestic wastewater under the simulated conditions of Thailand

AbstractSerious concerns have been raised about the sustainability of conventional mechanized linear wastewater treatment systems in the developing world. Bangkok in Thailand is no exception to these concerns, and merits closer examination. This paper is aimed at unveiling the fundamental facts and characteristics relating to the organic degradation potentials of domestic wastewater in Bangkok. It is supported by evidence from simple laboratory experiments in which existing local conditions were simulated. The results showed that greywater‐like qualities of domestic wastewater do predominate in Bangkok, most probably as a result of three main factors: (1) continued use of leaching septic tanks, (2) the tradition of using water after defecation, instead of toilet paper, and (3) high organic degradation potentials under tropical monsoon conditions. Considering the small organic content, coupled with high organic degradation rates of the freshly collected greywater‐based sewage in Bangkok, low‐cost and decentralized natural treatment systems could be far more suitable for environmental sustainability in such tropical monsoon areas than the implementation of large‐scale sewage works.

Seasonal transition of predominant precipitation type and lightning activity over tropical monsoon areas derived from TRMM observations

Monthly statistics from TRMM‐PR and LIS observations for the three years 1998 to 2000 describe large‐scale features in rainfall and lightning activity during pre‐monsoon and monsoon periods of the Asian and South American summer monsoons. Heavy (∼5–10 mm/day) pre‐monsoon rainfall in the one or two months before onset was widespread mainly over land. Pre‐monsoon rainfall was highly convective and characterized by active lightning, a high ratio of convective rain, and high echo tops. After onset, in contrast, intense rains also occurred over the ocean and land, however, convective intensity over land was diminished. Lightning activity was suppressed over the Amazon basin and Bangladesh during the latter half of the summer monsoon.

Experience and Practices on Flood Control in Vietnam

Vietnam is situated in the tropical monsoon area and the coastal areas are repeatedly hit by devastating storms and typhoons. Protective sea dikes are frequently overtopped or breached, and the resulting flooding causes loss of life and damage to agricultural land and infrastructure. In recent years, 361 kilometers of dikes have been upgraded in the coastal area of the five northern provinces of the Red River Delta. Master plans for measures in the Red River Delta, Central Vietnam, and the Mekong Delta have been completed or are in preparation. This paper provides a review of the present situation in Vietnam. Special attention is paid to the necessary upgrading of the design methodology, the development of appropriate construction techniques and capacity building, and the resulting actions relating to the management aspects of the flood defenses.

Hydrogeological Condition and Groundwater Behavior in Low Land, Thailand

In tropical-monsoon area, Southeast Asia, there are many flood plains. Much irrigation water is need for paddy fields, but there are many paddy fields with no irrigation system. So farmer supplies groundwater for lack of water. But there is no observation site to monitoring groundwater, rain, flood and river water. To investigate the hydrogeological and groundwater behavior in low land with flood, 1-site rain meter, 1-site river water level and 22-site groundwater observation wells are set in this study area. The authors make cross sectional geological map using soil log data in 22-boring site and discuss hydrological conditions and groundwater behavior using these data. There are two-main aquifers in this area. First aquifer is highly influenced by ground surface conditions. Groundwater levels which directly contact with Yom-River is same behavior with river water level. And there are many commercial sand pits in this study area so groundwater level existing in near ground surface is highly influenced by water infiltrates through these sand pits.

Soil Conservation in Estate Crop Plantation under Tropical Monsoon Area

Soil Conservation in Estate Crop Plantation under Tropical Monsoon Area

Water Requirements for Direct Seeding of Rice in the Tropical Monsoon Area

Water Requirements for Direct Seeding of Rice in the Tropical Monsoon Area

Erratum to : Land Leveling by Laser Beam-controlled Motor Grader for Rice Doublecropping under Direct Seeding Culture in Tropical Monsoon Area

Erratum to : Land Leveling by Laser Beam-controlled Motor Grader for Rice Doublecropping under Direct Seeding Culture in Tropical Monsoon Area

A Method to Estimate the Return Period of the Irrigation-less Dry Season and to Prepare Countermeasures against Water Shortage for Rice Double Cropping in Tropical Monsoon Area

A Method to Estimate the Return Period of the Irrigation-less Dry Season and to Prepare Countermeasures against Water Shortage for Rice Double Cropping in Tropical Monsoon Area

Land Leveling by Laser Beam-controlled Motor Grader for Rice Doublecropping under Direct Seeding Culture in Tropical Monsoon Area

Land Leveling by Laser Beam-controlled Motor Grader for Rice Doublecropping under Direct Seeding Culture in Tropical Monsoon Area

DDC·FDC Rule Curves for Large Reservoirs in Tropical Monsoon Areas

A set of DDC·FDC Rule Curves for Bhumibol and Sirkit Reservoirs in Thailand weredeveloped. The concept is applicable for operation of large reservoirs in any tropical monsoon region with rice paddy agriculture. They assume that the irrigation demand for a reservoir is reciprocal to inflow to the reservoir, which was remarkably well satisfied in the Bhumibol Reservoir in Chao Phraya River Basin. DDC·FDC Rule Curves are so named since they are the solutions of a chance constraint reservoir operation model where drought duration curves (DDC) and flood duration curves (FDC) were used as deterministic equivallence of sum of future streamflows. The obtained rule curves suggested that the Chao Phraya reservoir system was not large enough to provide as much water required now. In order to hold a 5% failture rate, with the storage of 1990 and 1991, as much as 60% of supply cutmay be necessary.

Rice Double Cropping and Management of Irrigation Systems in the Tropical Monsoon Area.

Rice Double Cropping and Management of Irrigation Systems in the Tropical Monsoon Area.

GMS赤外雲画像を用いた雲の広域分布とその季節変化の解析

Climatological large-scale features of the cloud distribution and their seasonal variation are investigated using cloudiness data derived from GMS-IR cloud images for the area between 90°E-170°W and 50°S-50°N. The large-scale distribution of clouds with tops determined to be above the 700mb level and the seasonal change in this distribution are described quantitatively for the three years from June 1983 to June 1986 except June 1984. The distribution and seasonal variation in cloud-top-height and cloud type (tall convective clouds and stratiform clouds) are investigated by computing a ratio between the amount of high-cloudiness (tops higher than 400mb level) and the amount of high- and middle-cloudiness (tops higher than 700mb level) and by examining the standard deviation of cloud-top-height in 1°×1° areas covered with cloud.Results of this study show that the maximum cloudiness (-4/10) is observed in the tropics except east of 150°E with a secondary maximum (3/10-4/10) in the mid-latitudes along the cyclone tracks, and the minimum cloudiness (1/10-2/10) is observed around the subtropical highs. The annual mean cloud-top-height is higher in the tropics than in the mid-latitudes. In the mid-latitudes, a significant difference in cloud-top-height between cyclone tracks is observed in both hemispheres; the mean cloud-top-height along the lowest-latitude cyclone tracks is much higher than along the other cyclone tracks.Large annual variations in cloudiness (2/10-4/10) are observed in tropical monsoon areas. In addition, cloud-top-height decreases significantly during the winter over continents and their vicinity (within about 1000km) for the tropical monsoon areas, which suggests deep convection is strongly suppressed there and active deep convection, which may be enhanced with a cold surge, is restricted to the regions away from the continents during the winter. The decrease of cloud-top-height during the winter is also observed for the region from the southern part of China to Japan, which corresponds to a subtropical monsoon area. Over the southern part of China and the East China Sea, this large seasonal variation of cloud-top-height is accompanied by a significant seasonal change in cloud type; tall convective clouds in the warm season to stratiform middle-clouds in the cold season. In addition to-the tropical and subtropical monsoon areas, tall convective clouds also increase over the Asian Continent even in the higher-latitude to 50°N during the summer and high-cloudiness increases to ti 2/10. This is significantly different from the fact that high-cloudiness over the Australian Continent is small (-0.5/10) throughout the year except for the tropical monsoon area.