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Asada Yohei Kimura Masaomi Azechi Issaku Iida Toshiaki Kubo Naritaka 《Paddy and Water Environment》2019,17(3):351-358
Paddy and Water Environment - Leakage of agricultural pipes has been increasingly frequent problems due to corrosion, loosening of joints, and cracks, which result in the subsidence of peripheral... 相似文献
2.
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. 相似文献
3.
Quang Huy Hoang Naritaka Kubo Ngan Giang Hoang Hajime Tanji 《Paddy and Water Environment》2009,7(2):123-133
Ba Lai Irrigation Project is located at coastal area in the Mekong Delta. In dry season when the flow rate decreases and the
strong east wind blows into the delta, the salinity intrusion increases and seriously affects agricultural and domestic water
use. Intakes of Ba Lai system have to be closed for 1–3 months depending on their locations, and no water supply during this
period often causes water pollution in the project area. In order to solve such problems, this study aims to seek gate operation
procedures for salinity control and water environment improvement. A numerical model is developed to simulate water movement,
salinity concentration and duration of remaining water (water age) within the system under three scenarios: (1) without control
structures, (2) with available control structures, (3) with the full control structures. Through the numerical simulations,
control structures are confirmed to be an effective measure for the salinity control and suitable gate operation schedules
are proposed to improve the water environment in the project. 相似文献
4.
The Unsteady Irrigation Water Distribution and Consumption (UIWDC) model is applied to analyze causes of uneven water distribution between the upstream and downstream beneficial areas of the Mae Lao Irrigation Scheme (MLIS). The uneven water distribution may be caused by inadequate water distribution facilities or improper operation rule; therefore, its causes are examined systematically and quantitatively from the aspects of “water allocation” and “operation rule”. The water allocation is considered focusing on the dry season irrigation, where equity and efficiency should be especially balanced because of the scare water resources. The “EQTY index” (the equity index) is defined to widen the range of consideration between the equity and the efficiency, instead of alternative judgment of which has a priority. The operation rule for facilities in the MLIS is assumed considering their capacities, and two coordinate values of “ineffective spillage” and “water deficit” in the scheduled areas are incorporated into operation rule to quantitatively diagnose the system performance. As a result, the original causes of uneven water distribution will presumably be identified. The informative and quantitative results are utilized to set a new benchmark performance of the MLIS for the water distribution. It can be described by the “Expected Ratio of Irrigable Area” (ERIA) and “Present Ratio of Irrigable Area” (PRIA). Based on this standard, the general recommendations can be more concretely proposed to raise the water distribution performance of the MLIS such as by improving distribution facilities and/or by installing vertical pumps. 相似文献
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Paddy and Water Environment - Check gates being installed in a main open canal work to maintain water at a constant level in order to ensure water distribution to secondary... 相似文献
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The Mae Lao Irrigation Scheme is one of the largest irrigation projects in Northern Thailand. According to the field reconnaissance,
water shortage usually occurs during the dry season. And it is very difficult to equally distribute available water to the
paddy fields from the upstream to the downstream parts of the system. To understand and identify the causes of the problems,
the measurement of water level and flow rate along all canals may be effective. However, it is not easy to achieve this in
such a large-scale irrigation system. Thus, the numerical simulation becomes the second option. The objective of this study
is to identify and quantify the real water shortage causes by developing an Unsteady Irrigation Water Distribution and Consumption
model which can simulate the water movement and consumption in the whole irrigation system. The beneficial area of the right
main canal is modeled based on the physical aspect of the system. The components of the model consist of canal networks, control
structures, and paddy fields. A canal is divided into several portions called reach. The Saint-Venant equations are applied
to describe the unsteady water movement in each reach. Flow movement at the control structure is expressed by the boundary
condition. The paddy fields are modeled to make paddy block and connected to each reach. The water consumption in each paddy
block is estimated by Paddy Tank model. The numerical model is successfully developed showing the ability to simulate the
water movement and consumption properties in this irrigation system. 相似文献
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