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.