受水区生态系统对南水北调工程的响应

南水北调工程的运行将引起受水区河流水生维管束植物的数量减少、东线洪泽湖的水质复杂化、受水区降水增多和温度降低以及受水区植被面积增加,从而改变流域的生态结构.因此,在实施南水北调工程的同时,应保持河流形态的异质性和生境的多样性,充分认识生态系统过程的非线性和结果的不确定性,并实施相应的环境监测以便及时发现和解决问题;确保受水区生态在自主性基础上进行恢复,努力使南水北调工程对受水区的生态起最大积极作用,使南水北调工程成为可持续发展的生态南水北调工程.     

Isotope hydrology and baseflow geochemistry in natural and human-altered watersheds in the Inland Pacific Northwest,USA

This study presents a stable isotope hydrology and geochemical analysis in the inland Pacific Northwest (PNW) of the USA. Isotope ratios were used to estimate mean transit times (MTTs) in natural and human-altered watersheds using the FLOWPC program. Isotope ratios in precipitation resulted in a regional meteoric water line of δ²H?=?7.42·δ¹⁸O?+?0.88 (n?=?316; r²?=?0.97). Isotope compositions exhibited a strong temperature-dependent seasonality. Despite this seasonal variation, the stream δ¹⁸O variation was small. A significant regression (τ?=?0.11D^?1.09; r²?=?0.83) between baseflow MTTs and the damping ratio was found. Baseflow MTTs ranged from 0.4 to 0.6 years (human-altered), 0.7 to 1.7 years (mining-altered), and 0.7 to 3.2 years (forested). Greater MTTs were represented by more homogenous aqueous chemistry whereas smaller MTTs resulted in more dynamic compositions. The isotope and geochemical data presented provide a baseline for future hydrological modelling in the inland PNW.     

Comparison of sample preparation methods for stable isotope analysis of dissolved sulphate in forested watersheds

Pretreatment methods for measuring stable sulphur (δ³⁴S) and oxygen (δ¹⁸O) isotope ratios of dissolved sulphate from watersheds have evolved throughout the last few decades. The current study evaluated if there are differences in the measured stable S and O isotope values of dissolved sulphate from forested watersheds when pretreated using three different methods: Method 1 (M1): adsorb sulphate on anion exchange resins and send directly to isotope facility; Method 2 (M2): adsorb sulphate on anion exchange resins, extract sulphate from anion exchange resins, and send the produced BaSO₄ to the isotope facility; and Method 3 (M3): directly precipitate BaSO₄ without anion exchange resins with the precipitates being sent to the isotope facility. We found an excellent agreement of the δ³⁴S_sulphate values among all the three methods. However, some differences were observed in the δ¹⁸O_sulphate values (M1 versus M2:?1.5 ‰; M1 versus M3:?1.2 ‰) associated with possible O contamination before isotope measurement. Several approaches are recommended to improve the pretreatment procedures for δ¹⁸O_sulphate analysis.     

雷达测雨及临近预报在中小流域水文视角下的应用评估

本文选取了2012年“苏拉”、2014年“海贝思”、2016年“尼伯特”三场台风在梅溪流域引发的三场不同类型降雨过程,探究了雷达测雨及临近预报在中小流域水文预报中的应用前景。采用24h累积雨量相对误差RE、时空两个维度均方根误差与相应维度均值的比值m-RMSE、平均绝对误差RMAE和平均偏差RMB等指标,基于地面雨量站的观测值评估雷达测雨以及1h、2h、3h预见期的集合临近预报,结果表明：雷达测雨总体上与地面雨量站观测值较为接近,不同类型降雨的RE值均在3%左右;时空分布均匀的降雨,临近预报效果优于短历时降雨和强降雨的临近预报效果,且随着预见期的延长,时空分布均匀的降雨预报效果更稳定,短历时降雨和强降雨的预报精度下降明显。因此,高时空分辨率的雷达测雨及临近预报在中小流域水文预报中有较好的应用前景,但短历时降雨和强降雨还需进一步研究。     

交互标记控制的快速网格分割

提出一种快速的三维网格分割算法。与大多数针对顶点集合的分割不同,此算法是一种面集分割,对网格的曲率估计位于相邻两个面之间。在分水岭算法的基础上,由用户交互提供分割的指示标记,完成网格曲面分割。因此不存在过度分割、噪音干扰等问题。同时利用极小值原理,使得分割结果更接近人的主观视觉原理。实验证明分割过程是快速的,能够满足交互的需要。     

岚河流域产沙量的影响因素分析

通过对岚河流域土壤侵蚀现状及降雨、径流、泥沙资料的研究，发现该流域年有效降雨量、有效降雨强度、年洪峰总量与流域产沙量之间有着较好的相关关系。这一发现不仅满足了流域产沙预报的要求，而且还为该流域的流域综合治理提供了科学依据。