MAIN EXISTING IRRIGATION SYSTEMS IN THE SUB-BASINS OF THE TONLE SAP LAKE OF CAMBODIA

The Tonle Sap Lake and its complex tributaries are the main water body and water courses of Cambodia. The catchment area of the lake is generally divided into twelve major sub-basins. The tributaries of the lake have great potential of water resources for agricultural and industrial development. The river networks and existing irrigation projects are not well surveyed. A survey trip was conducted around the lake. The aim of this trip is to understand the river networks and identify main existing irrigation systems in the sub-basins of the Tonle Sap Lake. In this poster, we are mainly focused on the existing irrigation schemes. The schemes are classified into five categories. (1) “Surface runoff collector”: it is formed by a small dike to collect surface runoff from upstream part. The water collected is used as a supplementary water source for rainy season cultivation and for irrigating a small area of dry season cultivation. (2) “Dam reservoir”: a dam is put in place on a river to store the river runoff during the rainy season and the water stored is supplied to a command area in the dry season. (3) “Indirect diversion”: it is characterized by a diversion structure and a storage reservoir. Water is diverted and stored in the reservoir during the rainy season and used for dry season cultivation. (4) “Direct diversion”: characteristic of this type is similar to that of the indirect diversion, except the river water is diverted directly to irrigated area without storing in a reservoir. (5) “Flood storage”: it is generally developed in the floodplain of the Tonle Sap Lake. A ring dike prevents floodwater from entering the reservoir and rainy season rice is grown inside the dike. After harvesting, the gates on the ring dike are opened to receive floodwater. The water is stored inside the dike for cultivating dry season rice outside the dike. This study found that there are only small-scale irrigation schemes developed around/in the Tonle Sap Lake. The water resources of this lake have not been effectively used

Models of irrigation system for Pursat basin planning

The Mekong River and the Tonle Sap Great Lake in Cambodia have vast floodplain suitable for rice-based farming system. The Tonle Sap Basin, defined as the catchments of the Tonle Sap River at its confluence with the Mekong River and other 11 main tributaries draining higher ground on all sides of the basin enclosing 44% of Cambodia’s land area. The Pursat River is one of tributaries of the Tonle Sap Great Lake. It originates at Cardamom Mountains and has very good potential for agricultural development. In this paper, we aim at applying three models of irrigation system for basin planning: Chinit (Dam-Reservoir Irrigation), West Baray (Reservoir Irrigation) and Batheay (Shallow Reservoir Irrigation) to Pursat Basin (one of sub-basin of the Tonle Sap Great Lake). Chinit Dam-Reservoir stores water supplied by one of tributaries of Tonle Sap Great Lake, the Chinit River, located in Kampong Thom Province. Spillway is built to pass up inundation and to release water to downstream part. The rest of water in the Dam-Reservoir is distributed to the paddy field by main canal, secondary canals and tertiary canals. This system can be put at the upstream part of the Pursat River, mountainous area. The West Baray Irrigation system is characterized by a reservoir combined with a dike system in the floodplain of the Tonle Sap Great Lake and an irrigation system situated in Siem Reap province. The reservoir is supplied by a tributary of the Tonle Sap Great Lake, the Siem Reap River, in rainy season. The water is distributed to irrigation area in dry season. A small dike system was constructed in the Tonle Sap floodplain for retarding and storing floodwater. The stored floodwater is used as an additional water source for dry season cultivation. This system can be placed at the central plain of the Pursat Basin. Batheay reservoir directly receives floodwater from the Mekong River. It functions as both a reservoir and a paddy field. In wet season, dike around the Batheay reservoir prevents floodwater from entering the reservoir. Rainy season rice is grown inside the reservoir. After harvesting, gates around the reservoir are opened to receive floodwater. The water is stored for cultivating dry season rice outside the reservoir. This system can be put at the downstream part of the Pursat River, floodplain area of Tonle Sap River

PADDY IRRIGATION SYSTEM USING SHALLOW RESERVOIR IN THE MEKONG RIVER FLOODPLAIN

peer reviewedThe Tonle Sap Great Lake and the Mekong River in Cambodia have huge floodplain suitable for rice-based farming system and potential water resources for farming. Studies to exploit the flood and the water resources of the lake and the river have not been well conducted yet. Batheay irrigation system is located in the floodplain of the Tonle Sap River and the Mekong River. In this research, the irrigation system is studied as a model site for future development of the floodplain of the Tonle Sap Great Lake and the Mekong River. Batheay reservoir directly receives floodwater from the Mekong. It functions as both a reservoir and a paddy field. In wet season, dike around the Batheay reservoir prevents floodwater from entering the reservoir. Rainy season rice is grown inside the reservoir. After harvesting, gates around the reservoir are opened to receive floodwater. The water is stored for cultivating dry season rice outside the reservoir. In this work, we attempt to study water management of the Batheay irrigation system by analyzing water use pattern in the irrigation system and uncover effectiveness of the system. A development scenario for the floodplain of the Mekong River is then proposed

Application of the TANK Model to a Tropical Monsoon Catchment in the Tonle Sap Lake Region of Cambodia

peer reviewedThis paper presents an application of TANK Model to a sub-catchment of the Tonle Sap Lake of Cambodia. The TANK Model was developed in Japan and was reported as being successfully applied to many river basins in Africa, Asia, Europe and the United States. The objective of this study is to investigate the performance of the TANK Model in tropical monsoon climate condition. The studied area is a sub-catchment of the Tonle Sap Lake. Two automatic hydrological stations and four automatic telemetry meteorological stations were installed in the sub-catchment. Rating curves at the two hydrological stations was established. The performances of the rating curves and the TANK model were assessed by four standard statistical evaluations. The model was calibrated by discharge derived from the rating curves. The runoff pattern from the TANK Model correlated closely with rainfall pattern. The model could estimate runoff for the wet season, except for some peak flows generated from delayed runoffs. However, the model tended to overestimate dry season flow and react faster to rainfall events in the dry season.CUI-ITC0

Ring dike system to harness floodwater from the Mekong River for paddy rice cultivation in the Tonle Sap Lake floodplain in Cambodia

Located in the floodplain of the Mekong River and the Tonle Sap River, Batheay irrigation system and its reservoir directly receive floodwater from the Mekong. The Batheay reservoir formedby a ring dike functions as botha reservoir anda paddy field. In thewet season, the ring dike prevents floodwater fromentering the reservoir and rainy season rice is growninside the dike. After harvesting, the gateson the ring dike are openedto receive floodwater. The water is stored inside the dike for cultivating dry season rice outside the dike. In this paper, the irrigation system is studied as a model site for future development of the floodplain of the Tonle Sap Lake of Cambodia. Specifically, this paper is concerned with the study of water balance and analysis of the hydrologic components of the Batheay irrigation system, and the effectiveness of the ring dike system. The study found that floodwater of the Mekong River contributed about 74% to the total inflow to the Batheay reservoir. Contributions to the total water supply of reservoir water, floodwater remaining in the fields, and precipitation were 73, 12, and 15%, respectively. The efficiency of the systemwas found to be 92%. The dike system is expected to be a paradigm for the floodplain of the Tonle Sap Lake

Model of Irrigation Development for Floodplain of the Tonle Sap Great Lake

Rice is a staple crop in Cambodia. To meet the large requirement of rice consumption due to rapid increased population and to boost the economy, the rice production in this country needs to be enhanced. The Tonle Sap Great Lake of Cambodia has huge floodplain suitable for large amount for rice production and potential water resources for rice-based farming system. Due to large variation of water level of the lake, some areas around the lake are flooded in wet season and shortage of water in dry season. Studies to exploit the flood and the water rsources of the lake and its tributaries have not been well conducted yet. The West Baray and Batheay irrigation systems are located in the floodplain of the Tonle Sap Great Lake and the Mekong River. In this research, the irrigation systems are studied as model sites for future development of the floodplain of the Tonle Sap Great Lake

Water-Energy-Food Nexus in a Transboundary River Basin:

VK: T20702The water-energy-food nexus is promoted as a new approach for research and policy-making. But what does the nexus mean in practice and what kinds of benefits does it bring? In this article we share our experiences with using a nexus approach in Cambodia’s Tonle Sap Lake area. We conclude that water, energy and food security are very closely linked, both in the Tonle Sap and in the transboundary Mekong River Basin generally. The current drive for large-scale hydropower threatens water and food security at both local and national scales. Hence, the nexus provides a relevant starting point for promoting sustainable development in the Mekong. We also identify and discuss two parallel dimensions for the nexus, with one focusing on research and analysis and the other on integrated planning and cross-sectoral collaboration. In our study, the nexus approach was particularly useful in facilitating collaboration and stakeholder engagement. This was because the nexus approach clearly defines the main themes included inthe process, and at the same time widens the discussion from mere water resource management into the broader aspects of water, energy and food security.Peer reviewe

POTENTIAL OF WATER RESOURCES OF PURSAT BASIN FOR IRRIGATION DEVELOPMENT

peer reviewedPursat River, one of the tributaries, flows into the Great Lake Tonle Sap, located in Pursat province, 187 km from Phnom Penh. Pursat River originates in Kbal Kmaoch Mountain at an elevation of 1,425m. The main stream joins with Prey Khlong River and Arai River which originate in Orall Mountain at the elevation of 1,813m, the highest mountain in Cambodia. Large of paddy field in the province is irrigated by the river. The lack of year round management of irrigation system along the river is a serious constraint to social and economic development, and poverty reduction in the province. The objective of the research is to discover the appropriate way to develop the irrigation system along the river. The study attempts to uncover the historical development of the river and water use along the river. The research also reveals the appropriate way to put the right system to the right place. The analysis will review the estimation of river flow and total annual flow, an amount of water to be withdrawn from the river, which will be simulated based on meteorological and hydrologic data, and field investigation

DEVELOPMENT OF SHALLOW RESERVOIR IRRIGATION BY USING FLOODWATER FOR PADDY RICE CULTIVATION

peer reviewedThe Tonle Sap Great Lake and the Mekong River in Cambodia have huge floodplain suitable for rice-based farming system and potential water resources for farming. Studies to exploit the flood and the water resources of the lake and the river have not been well conducted yet. Batheay irrigation system is located in the floodplain of the Tonle Sap River and the Mekong River. In this research, the irrigation system is studied as a model site for future development of the floodplain of the Tonle Sap Great Lake and the Mekong River. Batheay reservoir directly receives floodwater from the Mekong. It functions as both a reservoir and a paddy field. In wet season, dike around the Batheay reservoir prevents floodwater from entering the reservoir. Rainy season rice is grown inside the reservoir. After harvesting, gates around the reservoir are opened to receive floodwater. The water is stored for cultivating dry season rice outside the reservoir. In this work, we attempt to study water management of the Batheay irrigation system by analyzing water use pattern in the irrigation system and uncover effectiveness of the system. This study plays a vital role in the study of the Tonle Sap Great Lake system in our future research