Ancient South-East Asia

2009 ◽  
Author(s):  
Charles R. Ortloff
Keyword(s):  
Water Withdrawal ◽  
Mekong River ◽  
Land Area ◽  
Rice Agriculture ◽  
Groundwater Levels ◽  
Water Flows ◽  
Tonle Sap ◽  
Total Capacity ◽  
North Lake ◽  
Lake Tonle Sap

Cambodia is situated in southeast Asia on the coast of the Gulf of Thailand and shares borders with Vietnam to the east, Thailand to the west, and Laos to the north. Lake Tonle Sap occupies ~2.5% of Cambodia’s land area and plays a vital role in the rice agriculture of the country. The total cultivatable area is about 2.1 million hectares, of which 1.8 million is devoted to rice agriculture. The growing season is largely coupled to the monsoon cycles: the bimodal wet season starts in May and ends in October with peaks in June and September/ October resulting from diVerent rainfall origins. Rainfall levels vary around the country: although average levels are about 1.5 m, amounts vary from about 1.0m at Svay Check in the western province of Banteay Meanchey to nearly 4.7m in the southern province of Kampot. The Tonle Sap River reverses flow twice each year: from July to October, water flows into Tonle Sap Lake from branches of the Mekong River, swelling its area from 2,600 to 10,500 km<sup>2</sup>; in November when the flow rate of the Mekong River decreases, the Tonle Sap River reverses flow and water flows into the Mekong once again. Since 85% of Cambodia’s land area is included in the Mekong River basin, river water levels coupled to groundwater levels play a role in agricultural systems. The dry season from November to April requires irrigation to support rice agriculture making water storage and high groundwater levels important. Based on recent research (FAO 2005), the net renewable water balance (volume in flows minus volume) is equal to about 120km<sup>3</sup> with about 18 km<sup>3</sup> stored in groundwater reduced by 13 km<sup>3</sup> per year by river drainage. Of the total amount of water withdrawal per year (520_10<sup>6</sup>m<sup>3</sup>), about 94% is devoted to agriculture; given the dependence on rice farming through the ages, it is likely that a similar percentage was used for agriculture in ancient times as now to support like-sized agrarian populations. In the 10th to 14th centuries ce, Angkor’s water supply system was based on four (baray) reservoirs (not all functioning simultaneously) with a total capacity of 100–150_10<sup>6</sup>m<sup>3</sup>.

scholarly journals Evaluating Cryospheric Water Withdrawal and Virtual Water Flows in Tarim River Basin of China: An Input–Output Analysis

2021 ◽  
Vol 13 (14) ◽  
pp. 7589
Author(s):  
Yang Yang ◽  
Shiwei Liu ◽  
Cunde Xiao ◽  
Cuiyang Feng ◽  
Chenyu Li
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Socioeconomic Development ◽  
Virtual Water ◽  
Water Withdrawal ◽  
Tarim River ◽  
Tarim River Basin ◽  
Input Output ◽  
Output Analysis ◽  
Water Flows

In Tarim River Basin (TRB), the retreat of glacier and snow cover reduction due to climate warming threatens the regional economy of downstream basins that critically depends on meltwater. However, the quantitative evaluation of its impact on multiple sectors of the socioeconomic system is incomplete. Based on compiled regional input–output table of the year 2012, this study developed a method to analyze the relationships between economic activities and related meltwater withdrawal, as well as sectoral transfer. The results show that the direct meltwater withdrawal intensity (DMWI) of agriculture was much higher than other sectors, reaching 2348.02 m3/10,000 CNY. Except for A01 (agriculture) and A02 (mining and washing of coal), the embodied meltwater withdrawal (EMW) driven by the final demand of other sectors was greater than direct meltwater withdrawal, and all sectors required inflows of virtual water (72.45 × 108 m3, accounting for 29% of total supply from cryospheric water resources) for their production processes in 2012. For sectors with high DMWI, improving water-use efficiency is an effective way to reduce water withdrawal. To some extent, the unbalanced supply of cryospheric water resources due to geographical segregation can be regulated by virtual water flows from water-saving to water-intensive sectors. Such decisions can affect the balance between socioeconomic development and environment conservation for long-term sustainability.

scholarly journals Cambodian Freshwater Fish Assemblage Structure and Distribution Patterns: Using a Large-Scale Monitoring Network to Understand the Dynamics and Management Implications of Species Clusters in a Global Biodiversity Hotspot

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2506
Author(s):  
Kakada Pin ◽  
Savat Nut ◽  
Zeb Hogan ◽  
Sudeep Chandra ◽  
Samadee Saray ◽  
...  
Keyword(s):  
Indicator Species ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Mekong River ◽  
Biodiversity Hotspots ◽  
Fish Assemblage Structure ◽  
Assemblage Composition ◽  
Tonle Sap Lake ◽  
Tonle Sap ◽  
High Diversity

Mekong River Basin is one of the world’s fish biodiversity hotspots. Fisheries of the Cambodian Mekong are characterized by high diversity and productivity. However, few studies have focused on broad scale patterns and fish assemblage structure of this important system at a national level. Here, we describe spatial and seasonal variation in fish assemblages by analyzing one year of daily fish catch data sampled at 32 sites covering Cambodia’s main inland water bodies. We recorded 125 fish species. Four clusters were distinguished based on assemblage composition similarity, and 95 indicator species were identified to characterize each of the identified assemblage clusters. High diversity fish assemblages were associated with the upper Mekong system and Mekong/Bassac/Tonle Sap Rivers in Kandal Province and southern Tonle Sap Lake while lower diversity assemblages were observed in the Mekong River in Kratie and the northern area of the Tonle Sap Lake. We find significant variation in the assemblage composition between wet and dry seasons, indicating strong seasonal species turnover within clusters. Length–weight relationship analysis indicated a negative allometric growth among a majority of indicator species, reflecting suboptimal conditions for growth. Our study establishes contemporary structure and diversity patterns in the Lower Mekong River system of Cambodia, which can be used to map fish biodiversity hotspots and assess key indicative fish stocks’ statuses for conservation and management.

scholarly journals Assessing Climate Change Impacts on River Flows in the Tonle Sap Lake Basin, Cambodia

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 618 ◽  
Author(s):  
Chantha Oeurng ◽  
Thomas Cochrane ◽  
Sarit Chung ◽  
Mathias Kondolf ◽  
Thanapon Piman ◽  
...  
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Rapid Development ◽  
Dry Season ◽  
Freshwater Ecosystem ◽  
Lake Basin ◽  
River Flows ◽  
Water Flows ◽  
Tonle Sap Lake ◽  
Tonle Sap

The Tonle Sap is the most fertile and diverse freshwater ecosystem in Southeast Asia, receiving nurturing water flows from the Mekong and its immediate basin. In addition to rapid development in the Tonle Sap basin, climate change may threaten natural flow patterns that sustain its diversity. The impacts of climate change on river flows in 11 sub-basins contributing to the Tonle Sap Lake were assessed using the Soil and Water Assessment Tool (SWAT) model to quantify the potential magnitude of future hydrological alterations. Projected river flows from three General Circulation Models (GFDL-CM3, GISS-E2-R-CC and IPSL-CM5A-MR) for three time horizons (2030s, 2060s and 2090s) indicate a likely decrease in both the wet and dry season flows. The mean annual projected flow reductions range from 9 to 29%, 10 to 35% and 7 to 41% for the 2030s, 2060s and 2090s projections, respectively. Moreover, a decrease in extreme river flows (Q5 and Q95) was also found, which implies there could be a decline in flood magnitudes and an increase in drought occurrences throughout the basin. The results of this study provide insight for water resources planning and adaptation strategies for the river ecosystems during the dry season, when water flows are projected to decrease.

New synonyms and a new subspecies of Macrogomphus Selys, 1858 (Odonata: Gomphidae) from continental south-east Asia

Zootaxa ◽  
2019 ◽  
Vol 4615 (1) ◽  
pp. 57
Author(s):  
OLEG E. KOSTERIN
Keyword(s):  
East Asia ◽  
Great Lake ◽  
Diagnostic Character ◽  
South East Asia ◽  
New Subspecies ◽  
New Synonyms ◽  
Siem Reap ◽  
Tonle Sap ◽  
Lake Tonle Sap ◽  
The Relationship

The taxa of the genus Macrogomphus Selys, 1858 occurring in continental south-east Asia are reconsidered. Macrogomphus rivularis Förster, 1914 (described from Vietnam), M. borikhanensis Fraser, 1933 (described from Laos), and M. guilinensis Chao, 1983 (described from China), are synonymised with M. albardae Selys, 1878. The relationship and conspecificity of the latter with M. parallelogramma Burmeister, 1839 are doubtful, perhaps they are bona species. Males of M. albardae (and seemingly of parallelogramma as well) are approximately trimorphic for the pale pattern of the abdominal S3–S6, being of either a ‘dashed morph’ (with small isolated anteriolateral spots and conspicuous middorsal streaks), or a ‘ringed morph (with broad anterior rings and less conspicuous middorsal streaks), or an ‘intermediate morph’. Validity of the species M. matsukii Asahina, 1986 is doubted; its holotype could be an aberrant male of M. albardae. The main diagnostic character of M. albardae, M. phalantus Lieftinck, 1935 and probably M. parallelogramma, is clarified to be the structure of the cercus inner branch. M. phalantus jayavarman subsp. nov. is described from temporarily inundated forest at the northern bank of the great Lake Tonlé Sap of Cambodia (Siem Reap Province, 1.5 km SSW of Kampong Pluk village, 13.1956° N, 103.9725° E, 3 m a.s.l.), which is ca 1,300 km north and overseas from the presumed range of M. phalantus phalantus. 

scholarly journals Water-Energy-Food Nexus in a Transboundary River Basin: The Case of Tonle Sap Lake, Mekong River Basin

Water ◽  
2015 ◽  
Vol 7 (10) ◽  
pp. 5416-5436 ◽  
Author(s):  
Marko Keskinen ◽  
Paradis Someth ◽  
Aura Salmivaara ◽  
Matti Kummu
Keyword(s):  
River Basin ◽  
Mekong River ◽  
Mekong River Basin ◽  
Transboundary River ◽  
Transboundary River Basin ◽  
Tonle Sap Lake ◽  
Tonle Sap
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