黄河封河期冰凌预警地电测试技术研究
Ground resistivity technique measurement for ice jam early warning at freeze-up period of the Yellow River
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摘要: 黄河流域地形地貌相差悬殊,受西伯利亚和蒙古一带冷空气的影响,冬春季干、支流有不同程度的冰情出现.由于黄河凌情来势迅猛,水位急剧壅高,易决口成灾,开展冰凌预警研究是十分必要的.黄河封河期冰盖下流凌量及冰塞体的生长状况是黄河冰凌预警的关键要素,采用地电测试技术,对冰水两相流进行视电阻率测量,绘制电测深曲线,数字化模拟冰凌参数,评估冰塞体的生长及冰块堆积状况,为防凌减灾提供预警服务.测试结果表明,平稳流凌时,测深曲线经子波分解后阈值为10Ω·m左右,当出现局部冰塞时阈值达到100Ω·m左右,数值易于区分,基于电测深曲线的差异性进行冰凌预警的方法是可行的,可为防凌减灾提供预警服务.Abstract: The terrain landform and the topographic feature in the Yellow River val ey vary considerably. Affected by the cold air flow from the areas of Siberia and Mongolia,the noteworthy icing arises to various extents in the main and branch streams in winter and spring. The fierce violence of the formed ice jam flooding and abruptness in increment of water level could easily result in crevasse and cause natural calamity. It is,therefore,very important to carry out studies on ice jam early warning system. The amount of ice flows under the ice cover and the growth of ice bodies in the freeze up period of the Yellow River are the key factors for the Yellow River ice jam early warning In the study,we measure the two phase resistivity of ice water with the ground resistivity measurement technology,plot the resistivity diagrams,digitalize the parameters of the ice jam formation, and the evaluate the growth of ice bodies and the accumulation of ice bulks,which provides valuable information for the ice jam protection and the natural disaster reduction. The results indicate that,at the stable stage of ice flow,the threshold is around 10Ω·m fol owing the decomposition of the resistivity cure by wavelet analysis During partial blockage of ice jam,the threshold increases up to about 100Ω·m. The apparent difference in the thresholds can be a criterion for judging the ice jam early warning. A practical method for ice jam early warning is,therefore,proposed the based on dif erences shown on the ground resistivity curves.