Regional Consequences of Seawater Intrusion on Rice Productivity and Land Use in Coastal Area of the Mekong River Delta
Regional Consequences of Seawater Intrusion on Rice Productivity and Land Use in Coastal Area of the Mekong River Delta
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DOI：
10.6090/jarq.42.267
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发表时间：
2008-10-01
影响因子：
0.4
通讯作者：
Yokozawa, Masayuki
中科院分区：
文献类型：
--
作者：
Kotera, Akihiko;Sakamoto, Toshihiro;Yokozawa, Masayuki
本研究调查了越南湄公河三角洲沿海地区的水稻生产力，重点是海水入侵的影响和最近的土地利用变化在区域尺度上的关系。我们研究了2003 - 2005年沿海地区4个省30个地区的水稻产量统计数据，以及旱季期间在运河和河流中48个点观测到的平均盐度。作为与各地区水稻统计数据进行比较的海水入侵程度的指标，根据观测点的数据，通过空间插值得出各地区的平均盐度。结果表明，海水入侵是导致该地区水稻种植制度和土地利用方式区域差异的主要因素。水稻种植强度，这是定义为种植面积与地区面积的比例，随着运河水的含盐量的增加而下降，但水稻产量平均在该地区是独立的含盐量。为了避免水稻生长受到盐胁迫，沿海地区的水稻种植主要在雨季盐度季节性下降导致海水入侵减弱的时期进行。具体而言，在高盐度地区，水稻种植所需的无盐时间很短。在那里，水稻种植强度可能受到盐度的限制。此外，最近，沿海地区的稻田面积因土地用途改为水产养殖，特别是养虾场而减少。需要微咸水的水产养殖强度也受到海水入侵的限制。因此，湄公河三角洲沿海地区的水稻生产受到海水入侵和土地使用多样化之间相互关系的限制。
This study investigates rice productivity in the coastal area of the Mekong River Delta, Vietnam focusing on relationships with the influences of seawater intrusion and recent changes in the land use at regional scale. We examined the statistical data on rice production at 30 districts of 4 provinces in the coastal area for the years 2003-2005, together with the average salinity concentration observed at 48 points in canals and rivers during the dry season. As an index of the extent of seawater intrusion to be compared with rice statistical data in each district, average salinity of each district was derived by using spatial interpolation from the data in the observation points. It was shown that seawater intrusion was the major factor leading to regional differences in rice cropping systems and land use patterns in the region. Rice cropping intensities, which is defined as the ratio of planted area to district area, decreased with increasing salinity level in canal water, but rice yields averaged over the district are independent of the salinity level. To avoid salinity stress to rice growth, rice cultivation in the coastal area is mainly undertaken during the period when seawater intrusion is weakened by the seasonal decrease in salinity in the rainy season. Specifically, in districts with high salinity, the salinity-free duration required for rice cultivation is short. There, rice cropping intensities are potentially limited by the salinity. In addition, recently, the area of paddy fields in the coastal area has been decreased through land use conversion to aquaculture, especially shrimp farms. Intensity of aquaculture, which requires brackish water, was also limited by seawater intrusion. Thus., rice production in the coastal area of the Mekong Delta was limited by the interrelationship between seawater intrusion and land-use diversification.