Abstract

Measurements of Sulak River plume parameters in the Caspian Sea conducted from June 2 to 7, 2023, concurrently with satellite survey allowed tracing changes in water turbidity (WT) and suspended particulate matter (SPM) concentration in the near-mouth zone after the arrival of mudflow masses into the sea. Heavy rains in the mountains of Dagestan on May 31, 2023, caused mudflows, which entered, in particular, the Sulak River. Two days later, on June 2, mud masses, together with river water, flowed into the Caspian Sea. In the near-mouth zone, WT values exceeded 1000 NTU, which was beyond the allowable threshold of a portable turbidimeter employed for turbidity measurements. On June 2, 4, 5 and 7, quasi-synchronously with satellite imaging, measurements were conducted from a small boat using various oceanographic equipment. They were accompanied with water sampling for further determination of SPM concentration and mineral composition. The linear dependence revealed between WT and SPM concentration made it possible to calculate WT that could not be measured in situ: it amounted to 1247 NTU at SPM concentration of 1097.4 g/m³. Satellite data were used to compile WT maps using the Dogliotti 2015 algorithm. The results of satellite observations and in situ measurements showed that, within 2 days, WT and SPM concentration at the nearest to the river mouth station dropped sixfold and continued to decrease to the average values for this area in early June. Determined by X-ray phase analysis, the mineral composition of suspended solids on the day of mudflow arrival into the sea was represented mainly by clay minerals, their content reaching 75%. Later, by June 7, the mineral composition returned to the average values and the content of clay minerals did not exceed 44%.

中文翻译：

---

达吉斯坦山区泥石流后苏拉克河羽流参数的变化

摘要

2023 年 6 月 2 日至 7 日对里海苏拉克河羽流参数进行了测量，同时进行了卫星调查，可以追踪到了里海苏拉克河羽流到达后近口区水体浊度 (WT) 和悬浮颗粒物 (SPM) 浓度的变化。泥石流大量流入大海。2023 年 5 月 31 日，达吉斯坦山区暴雨引发泥石流，尤其是流入苏拉克河。两天后，即6月2日，泥团与河水一起流入里海。在近口区域，WT值超过1000 NTU，这超出了用于浊度测量的便携式浊度计的允许阈值。6月2日、4日、5日和7日，与卫星成像准同步，利用各种海洋学设备在一艘小船上进行了测量。他们还进行了水采样，以进一步测定 SPM 浓度和矿物质成分。WT和SPM浓度之间揭示的线性相关性使得计算无法在原位测量的WT成为可能：在SPM浓度为1097.4 g/m ³时其达到1247 NTU 。卫星数据用于使用 Dogliotti 2015 算法编译 WT 地图。卫星观测和现场测量结果显示，2天内，距河口站最近的WT和SPM浓度下降了6倍，并继续下降至6月初该地区的平均值。经X射线物相分析测定，泥石流入海当​​日悬浮物的矿物成分以粘土矿物为主，含量达到75%。随后，到6月7日，矿物成分恢复到平均值，粘土矿物含量不超过44%。