Bed elevation, bed surface grain size (D50 and D90), and water discharge- Waal, Pannerden Channel, Nederrijn, and IJssel, 1928-2020

Rijkswaterstaat has measured bed level along the Rhine branches since 1926 (Bovenrijn-Waal), 1928 (Pannerden Canal- Nederrijn), and 1941 (IJssel). The measurements were done using single beam echo sounders until 1999 and multibeam echo sounders since 1999-2002. Single beam measurements were taken at cross-sections spaced roughly 25 m apart and were averaged over 1 km. Multibeam measurements cover the river's entire length, and 100 m averaged data is provided here. Only cross-section averaged data is provided here. The error in bed elevation data (defined as two times the standard deviation) has been estimated to be up to 0.2-0.5 m until 1990; 0.2-0.3 m between 1990-1999, and 0.05-0.1 m since 1999 (Wiegmann, 2002).<br>Water discharge data at Lobith, Waal, and IJssel have been measured by Rijkswaterstaat using Ott current meters until 1999 and acoustic Doppler current profiler (ADCP) since 2000. Uncertainty related to Ott current meter measurement is smaller than 20% and smaller than 10% for ADCP. <br>Rijkswaterstaat has measured grain size data using digging buckets (until 1984) and grab-samplers (since 1984). We have included data from 1966, 1976, 1984, 2008, 2016, 2017, and 2020 measurement campaigns in this dataset. The samples were taken at cross-sections spaced 500 m to 1 km, with three samples (spaced 65 m) at each cross-section. The uncertainty of grain size data is high due to the high natural Spatio-temporal variability and limited spatial and temporal sampling density.

荷兰公共工程与水利管理局（Rijkswaterstaat）自1926年（上莱茵-瓦尔河河段）、1928年（潘讷尔登运河-下莱茵河河段）及1941年（艾瑟尔河河段）起，沿莱茵河各支流开展河床高程测量。1999年以前，测量工作均采用单波束测深仪（single beam echo sounders）完成；1999-2002年起逐步改用多波束测深仪（multibeam echo sounders）。单波束测量沿间距约25米的断面开展，数据以1千米为间隔取平均值；多波束测量覆盖整条河道，本数据集提供100米平均后的断面数据，且本数据集仅提供断面平均数据。1990年以前，河床高程数据的误差（定义为两倍标准差）估算值为0.2-0.5米；1990-1999年间为0.2-0.3米；1999年以来则为0.05-0.1米（Wiegmann, 2002）。
荷兰公共工程与水利管理局（Rijkswaterstaat）自1999年以前采用Ott流速仪（Ott current meters）、2000年起采用声学多普勒流速剖面仪（acoustic Doppler current profiler, ADCP），对洛比特（Lobith）、瓦尔河及艾瑟尔河的流量数据开展测量。其中，Ott流速仪测量的不确定度小于20%，声学多普勒流速剖面仪的测量不确定度则小于10%。
荷兰公共工程与水利管理局（Rijkswaterstaat）曾采用挖斗式采样器（1984年以前）与底泥采泥器（1984年以来）获取河床泥沙颗粒级配数据。本数据集纳入了1966、1976、1984、2008、2016、2017及2020年多轮测量的颗粒级配数据。采样沿间距500米至1千米的断面开展，每个断面处采集3个间距65米的样本。由于河床泥沙颗粒级配存在较强的自然时空变异性，且时空采样密度有限，该类数据的不确定度较高。