A combined technique of floodplain storage and reservoir irrigation for paddy rice cultivation

Abstract

This paper introduces an irrigation system developed in the floodplain of a lake and studies the water management technique of the irrigation system by estimating the total water balance of the whole system. The system is characterized by a reservoir combined with a dike system in the floodplain of the Tonle Sap Great Lake and an irrigation system. Two main models are used for calculating the total water balance. The first model is the water balance of the reservoir. The inputs to the model are water level of the reservoir, precipitation, lake evaporation, infiltration, and area-volume curve of the reservoir. The outputs are inflow and outflow of the reservoir. The supply from the reservoir to paddy fields is computed from the outflow. The second model is the water balance of paddy fields, based on which the water requirement in paddy fields is derived. The reference evapotranspiration needed to calculate the water requirement is simulated for monthly time series using the FAO Penman-Monteith model. Since there is no drainage network in the irrigation system, surface drainage and runoff are not included in the calculation of the water balance, and seepage is considered negligible in the flat floodplain area. The evapotranspiration, rice variety, soil type and irrigated area are used to simulate water consumption in paddy fields. Finally, the two models are connected to produce the total water balance from the reservoir to paddy fields. The total outflow from the reservoir is estimated and the total water consumption for dry season cultivation is also determined. Finally, the efficiency of the whole system is examined.

Paleoenvironmental history of the West Baray, Angkor (Cambodia)

“…The barays were constructed by building embankments around the intended perimeter using earth acquired by digging trenches inside the perimeter of the baray (5). The primary (65%) source of water and sediment to the West Baray is the Siem Reap River; the remaining 35% of the hydrologic input derives from direct precipitation (16,17). The Siem Reap River, one of three river catchments in the greater Angkor area today, drains an area that includes the Kulen Hills.…”

“…1). The baray floor inclines gently from the northeast to the southwest with an elevation difference of approximately 8 m between the northeast and southwest corners (16) (Fig. S1).…”

“…S1). If filled to its current maximum capacity, the baray would hold 53 million m 3 of water (16). It is generally assumed the baray was built in the first half of the 11th century, though the precise date is unknown (11).…”

Using AHP and Spatial Analysis to Determine Water Surface Storage Suitability in Cambodia

“…In addition, studies in Cambodia have shown that the Barays at Angkor have improved residents' quality of life in the Siem Reap province by preventing floods, supplying water during drought months, providing fishing grounds, and promoting tourism [21]. For example, local fishers each catch at least 3 kg (6.6 lbs) of fish daily from the Baray [16,21,22]. These studies have shown that water harvesting reservoirs can improve water storage, flood protection, and its residents' quality of life.…”

“…Despite this need to improve water resources infrastructure across the country, few studies have evaluated surface water storage sites, such as water harvesting reservoirs. Instead, previous studies have primarily focused on the performance and benefits of existing reservoirs and systems [16,17,22,26]. For example, Someth et al [16] conducted a water balance on the West Baray.…”