Delivering environmental flows in the Murray-Darling Basin (Australia)—legal and governance aspects

Abstract

The hydrology of water-dependent ecosystems around the world has been altered as a result of flow regulation and extraction for a variety of purposes including agricultural and urban water supply. The flow regime of the Murray-Darling Basin in Australia is no exception, with attendant impacts on the health of the environment. Restoration of parts of the flow regime is a key feature of environmental flow delivery. However, environmental flow delivery in a system that is managed primarily to provide a secure and stable supply for irrigation presents challenges for managers seeking to return more natural flow variability in line with ecosystem requirements. The institutional arrangements governing releases of water from storage can influence the ability of managers to respond to natural cues, such as naturally rising flows in a river. As such, the legal and governance aspects of environmental flow delivery are likely to be important influences on the outcomes achieved.

Editor Z.W. Kundzewicz; Guest editor M. Acreman

Citation Banks, S.A. and Docker, B.B., 2014. Delivering environmental flows in the Murray-Darling Basin (Australia)—legal and governance aspects. Hydrological Sciences Journal, 59 (3–4), 688–699.     

Assessment of environmental flows under limited data availability: case study of the Acheloos River,Greece

Abstract

The lower course of the Acheloos River is an important hydrosystem in Greece, heavily modified by a cascade of four hydropower dams upstream, which is now being extended by two more dams in the upper course. The design of the dams and hydropower facilities that are in operation has not considered any environmental criteria. However, in the last 50 years, numerous methodologies have been proposed to assess the negative impacts of such projects to both the abiotic and biotic environment, and to provide decision support towards establishing appropriate constraints on their operation, typically in terms of minimum flow requirements. In this study, seeking a more environmentally-friendly operation of the hydrosystem, we investigate the outflow policy from the most downstream dam, examining alternative environmental flow approaches. Accounting for data limitations, we recommend the basic flow method, which is parsimonious and suitable for Mediterranean rivers, whose flows exhibit strong variability across seasons. We also show that the wetted perimeter–discharge method, which is an elementary hydraulic approach, provides consistent results, even without using any flow data. Finally, we examine the adaptation of the proposed flow policy (including artificial flooding) to the real-time hydropower generation schedule, and the management of the resulting conflicts.

Editor Z.W. Kundzewicz; Guest editor M. Acreman

Citation Efstratiadis, A., Tegos, A., Varveris, A., and Koutsoyiannis, D., 2014. Assessment of environmental flows under limited data availability: case study of the Acheloos River, Greece. Hydrological Sciences Journal, 59 (3–4), 731–750.     

基于相机摄影测量的冰面反照率反演方法研究

雪冰反照率是冰川与积雪能量平衡计算的关键参数,也是观测的难点. 为测量冰面反照率,试验采用相机摄影测量技术,在祁连山十一冰川开展了自动拍摄、并利用共线方程进行冰川正射制图,在此基础上于2012年7月28日-8月18日在冰川表面开展了不同海拔梯度的反照率观测. 通过统计分析晴天与阴天观测反照率与对应点相机拍摄获取的RGB归一化指数之间的关系,对十一冰川进行冰面反照率参数化方法研究. 结果表明：晴天冰面反照率与RGB归一化指数存在明显的指数关系,拟合R²达到0.79;而阴天的统计关系较差,线性拟合R²仅为0.52. 据此尝试利用晴天的拟合公式对整个冰面进行反照率参数化,计算表明：在晴天冰川表面地形阴影区的反照率存在低估现象,而无阴影区的反照率估算结果可信度较高. 利用2013年的反照率观测数据进行了参数化方案的验证,结果表明：观测值与模拟值平均误差仅为0.037,表明利用RGB影像对反照率参数化具有一定的可用性和可靠性.     

天山乌鲁木齐河源1号冰川物质平衡高度变化特征及其对径流的影响

利用天山乌鲁木齐河源1号冰川1980-2010年的物质平衡、水文气象实测资料, 分析了1号冰川1980-2010年的各高度带物质平衡特征, 进而分析了1984-2010年纯积累和纯消融的变化特点及其与气象要素、冰川融水径流变化的关系. 结果表明: 1号冰川物质平衡处于持续的负平衡, 纯积累量与年降水的相关系数为-0.16, 纯消融量与年均温的相关系数为0.61, 与夏季(6-8月)气温的相关系数为0.78. 2010年1号冰川为有观测记录以来的最强消融年(b_n=-1 327 mm), 整个冰川处于消融区(平衡线高度大于海拔4 484 m, 积累区面积为0), 同时东、西支冰川各高度区间的物质平衡变化也与往年度显著不同, 说明2010年是1号冰川物质平衡变化的特殊年份, 也有可能1号冰川的物质平衡变化进入了一个新的亏损变化阶段. 对其径流数据的分析还表明, 温度对径流的影响大于降水对径流的影响.     

天山乌鲁木齐河源1号冰川物质平衡特征

统计了天山乌鲁木齐河源1号冰川自1980年以来冰川表面的单点物质平衡,分析了不同季节物质平衡及其冰川变化特征。研究表明,1号冰川厚度较之1959年平均减薄了9 599 mm;1997—2002年为实际观测以来连续的强负物质平衡时段,平均物质平衡为-739.6 mm /a。物质平衡与气温、降水的相关分析显示：1号冰川物质平衡主要取决于夏季平均气温的高低,二者具有较好的反相关关系（相关系数为-0.72）,而与降水的关系相对较差。20世纪80年代末以来,1号冰川退缩速度明显增大,尤以2000—2002年为甚,西支冰川退缩速度为连续的高值(退缩速度分别为6.92 m/a、6.95 m/a和6.25 m/a);东支冰川的退缩速度与高度大于4 200 m的高度带区间的平均物质平衡值有较好的相关关系（相关系数为0.65）,表明了1号冰川进退的动力主要源于冰川积累区的物质平衡大小。     

Invertebrate recolonisation of previously dry channels in the Rakaia River

Recolonisation of previously dry channels by stream invertebrates was studied in the Rakaia River during winter 1981 and summer 1982. The winter experiment continued for 42 days, with stable low flows, whereas the summer experiment was characterised by fluctuating large flows which caused it to be abandoned after 27 days. The fauna was dominated numerically by Chironomidae, a leptophlebiid mayfly (Deleatidium), and oligochaetes during the winter, and by Deleatidium alone during the summer. Recolonisation was considered complete after 33 days in winter and 15 days in summer. Flow fluctuations were the main factor affecting colonisation rates, and it was assumed that drift was the main source of colonising animals. Small freshes during low‐flow periods in winter resulted in a rapid increase in total density of invertebrates and number of taxa present and also affected the population structure of Deleatidium larvae in colonisation baskets. Before these freshes numbers had increased steadily over a 27 day period. In summer large floods during high flow periods initially decreased benthic invertebrate numbers in samples but numbers increased rapidly once the flood had passed. This appears to be the first study of its kind on a large unstable river system.     

Critical depths for passage in braided rivers,Canterbury, New Zealand

Riffles and points of divergence of branch channels in braided rivers are critical controls upon passage of fish and recreational boats because they are points at which depths are at a minimum. Depths on randomly selected riffles were measured in braided reaches of the Ashley, Hurunui, and Rakaia Rivers and related to discharge; minimum depths encountered in extended reaches of these rivers at a range of flows have also been measured. The data can be used to predict minimum available passage depths at a specified flow, or conversely, to predict the discharge required to maintain a specified minimum passage depth. However, presently available estimates of critical minimum depths required for various instream uses (migration of salmonids, jetboating) appear excessively conservative, and minimum depth requirements must be more accurately determined before instream flow needs can be properly assessed.     

青藏高原东南部贡嘎山海螺沟冰川冰下沉积物形成与变形

冰岩界面的冰川动力学是冰川系统的重要组成部分, 海螺沟冰川地处温暖湿润的海洋环境, 冰川运动速度较快, 冰川底部接近压融点, 是研究冰下过程的较理想地点. 在海螺沟冰川大型磨光面上浅显侵蚀坑内发现了碎屑物质. 对碎屑物质理化特征研究表明: 粒度特征、地球化学与石英砂SEM 分析表明沉积在冰岩界面上的物质来自于冰川底部的底碛层, 而不是冰上环境的产物. 偏光显微镜下观察到的冰下沉积物呈现出一系列塑性变形(微旋转、褶皱)和脆性变形(线性结构、支撑结构、断层)微观结构和构造. 两种变形结构的存在是碎屑物质在形成过程中其含水量波动情况的反映. 冰下碎屑物质是冰下融出、滞碛作用的共同产物. 在整个冰下碎屑物质形成与变形过程中, 由于冰下水系季节性变化带来的冰岩界面上冰川融水含量的波动起了决定性作用.     

祁连山冷龙岭宁缠河3号冰川表面流速特征分析

2009年9月对祁连山冷龙岭宁缠河3号冰川外围建立控制网, 于冰川表面布设了13根标志杆, 随后分别于2010年7月、2010年9月再次对设立在冰川表面的花杆点进行测量, 获取2009/2010年度、2009年9月-2010年7月与2010年7-9月3个时段宁缠河3号冰川表面流速.结果显示: 2009/2010年度宁缠河3号冰川最大流速出现在海拔4 430 m附近, 为3.76 m·a^-1;2009年9月-2010年7月表面流速最大值出现在海拔4 430 m附近, 为0.32 m·月^-1;2010年7-9月最大流速出现在海拔4 380 m附近, 为0.47 m·月^-1.总体来看, 2009/2010年度宁缠河3号冰川纵剖面上流速变化较为缓和, 显示出流速随海拔变化而变化的规律. 但不同季节表面流速在纵剖面上的分布情况不同, 横剖面上主流线附近流速最大, 向冰川两边逐渐递减, 各观测点均平行于主流线方向向冰川末端运动, 表现出冰川运动一般规律. 在冰川表面运动速度观测区域内东南边缘流速略大于西北边缘, 同时与规模相近的冰川运动速度相比, 宁缠河3号冰川运动速度较大.     

祁连山老虎沟12号冰川退缩对细菌优势种群影响的初步研究

随着全球冰川正在越来越多的地区融化, 冰川微生物资源很可能会由于冰川退缩而未被人类所发现就已受到生存的威胁而濒危.以祁连山老虎沟12号冰川消融区和末端雪样及末端土样为研究对象, 采用培养方法、分子鉴定, 研究冰川雪样优势菌群在冰川末端土样的分布状况及生理生化指标变化情况, 分析冰川细菌优势菌群在冰川退缩后适应非雪环境的能力.结果表明: 冰川末端雪样优势菌为1BW1和1BW2所代表的Pedobacter, 该属在冰川消融区雪样和冰川末端土样中未分离到; 冰川消融区雪样优势菌为2BW所代表的Acinetobacter, 该属在冰川末端雪样中的数量较少, 在冰川末端土样中的数量更少.不同采样位点16S rRNA序列相似性高的菌株其生理生化特征比相同采样位点的大.因此, 冰川冰退缩可能会引发冰川雪样中的优势种群不能适应新环境而灭绝. 应加强冰川细菌资源利用和保护的研究基础.