易涝易渍农田地下水动态特征

地下水动态是评价易涝易渍农田生产稳定性的重要指标,基于湖北四湖流域大量调查观测资料对此进行了研究。结果表明,易涝易渍农田地下水位存在明显的年、季差异,呈现出一定的波动性,在不同季节以及不同水平年间波动幅度不大,绝对偏差一般只有1 0~2 0 cm左右,最大不超过4 0 cm,地下水位呈现出在高水位上波动的特点;从微地形地貌看,沿江地势较高的农田其地下水平均埋深和地下水位波动与地势低洼的滨湖农田明显不同,前者明显大于后者。在较大尺度上当降水很接近时,农田地下水埋深随微地貌分异并不显著;对于水网密织的南方平原湖区,农田地下水位变化与周边水体相联系并受其影响,在农田涝渍防治中必须处理好农田与周边水体的关系。

Dynamic State of Groundwater in Farmland Vulnerable to Surface and Subsurface Waterlogging

Dynamic state of groundwater is an important index to evaluate produce stability of farmland vulnerable to subsurface waterlogging and subsurface waterlogging,it was studied based upon a lot of information obtained by investigation and observation in the four-lake watershed in Hubei province.Analysis showed that: ①A difference of groundwater table in a field vulnerable to surface and subsurface waterlogging is obviously existed in different years and seasons,it is with a certain fluctuation,however,the extent of the fluctuation is small,the absolute deviation of yearly average groundwater depth generally is only 10～20 cm or so,the maximum deviation of it is less than 40 cm,and groundwater table in the field is characterized by fluctuation in high water level;②In view of micro-topography or micro-landscape,the average depth of groundwater and its fluctuation in a high relief farmland along the banks of Yangtze River is evidently distinguished from a low farmland in lakeside,and the former is much more than that of the later,but the variation of the groundwater depth is not remarkable along with difference in micro-landscape when rainfall is extremely close at large scale;③In a plain region with a lot of lakes in southern China where a network of rivers are close and numerous,variation of groundwater table in a field connects with water body around the field,and is affected by it,so the relationship between farmland and water body around it should be well dealt with in prevention and control of waterloggong in a field.