A Shared Vision on the Transboundary Water Management Challenges of the Tagus River Basin

The Tagus River basin faces a growing water management challenge, as water demand and river regulation by large multi-purpose reservoirs lead to situations of water scarcity and mediocre conditions in some water bodies. The current situation and the impacts of increasing water demands are evaluated by a detailed river basin model which covers the whole river basin and includes the main hydraulic infrastructures and water uses of Spain and Portugal. Several indicators are computed from the model results to assess water demand satisfaction and the alteration of the hydrological regime, offering a better understanding of current hydro-climatic conditions in the basin. Results show that current water management practices have significantly altered the natural river flow conditions in the entire Tagus River basin. Water managers struggle to satisfy existing waters uses and increasing water demands will further accentuate these problems. The enforcement of new and planned environmental flow requirements may alleviate the conditions of some water bodies but will decrease the level of satisfaction of non-priority water demands. As additional measures are needed to improve water bodies status, water management and allocation policies must be revised at the river basin scale to improve the balance between water consumptive uses and environmental needs. A shared knowledge base and a common vision on the basin challenges will be required to achieve these goals and the datasets and tools applied in this study contribute to this needed transboundary cooperation.

     

When the river does not naturally flow: a case study of unsustainable management in the Tagus River (Spain)

ABSTRACT

This article assesses the main problems facing the Spanish Tagus River basin, and the management that has caused (or allowed) them. It examines the economic, social, environmental and political-institutional dimensions of Tagus River management in terms of sustainable development. We find that the institutions responsible for designing and implementing water policy in the Tagus basin have been unsuccessful in balancing the three classic dimensions of sustainability, resulting in systematic and recurrent failure to comply with the European Water Framework Directive and the principles of sustainable development.     

A Modelling Approach to Forecast the Effect of Climate Change on the Tagus-Segura Interbasin Water Transfer

This study was conducted in the upper Tagus River basin (UTRB), whose available water resources are partially transferred from the Entrepeñas and Buendía reservoirs after local needs satisfaction to the Segura River basin using the Tagus-Segura water transfer (TSWT), the largest hydraulic infrastructure in Spain. This study evaluates the climate change impact on the TSWT by considering future evaporation rates and bathymetric changes in the Entrepeñas and Buendía reservoirs. The findings of this study indicate a consistent decline in precipitation and an increase in temperature and evaporation under all climate impact scenarios. Consequently, inflows to the reservoirs will decline by 19% (RCP 4.5) and 53% (RCP 8.5) for 2070–2099, which could reduce water volumes that could be transferred to the Segura basin by more than 60%. The simulation of the TSWT operation rules, taking into account the impact of future evaporation and bathymetric changes, demonstrates an additional increase in reductions of water transfer of around 4%, which reveals the need to consider these effects in hydrological planning.

     

An Innovative Option Contract for Allocating Water in Inter-Basin Transfers: the Case of the Tagus-Segura Transfer in Spain

The Tagus-Segura Transfer (TST), the largest water infrastructure in Spain, connects the Tagus basin’s headwaters and the Segura basin, one of the most water-stressed areas in Europe. The need to increase the minimum environmental flows in the Tagus River and to meet new urban demands has lead to the redefinition of the TST’s management rules, what will cause a reduction of transferable volumes to the Segura basin. After evaluating the effects of this change in the whole Tagus-Segura system, focusing on the availability of irrigation water in the Segura, the environmental flows in the Tagus and the economic impacts on both basins; we propose an innovative two-tranche option contract that could reduce the negative impacts of the modification of the Transfer’s management rule, and represents an institutional innovation with respect to previous inter-basin water trading. We evaluate this contract with respect to spot and non-market scenarios. Results show that the proposed contract would reduce the impact of a change in the transfer’s management rule on water availability in the recipient area.     

Estimation of Small Reservoir Storage Capacities with Remote Sensing in the Brazilian Savannah Region

Small reservoirs play an important role in supporting the local economy in the savannah areas of Brazil and are primarily used for the provision of water for irrigation and watering livestock. Hundreds of small reservoirs have been built in the last few decades in the Preto River Basin, but efficient water management and sound planning are hindered by inadequate knowledge of the number, storage capacity and spatial distribution of reservoirs in the basin. The main reason for the lack of this information is that current methodologies for quantifying the physical parameters of reservoirs are laborious, time consuming and costly. To address this lack of data, a simple method to estimate reservoir storage volumes based on remotely sensed reservoir surface area measured with LANDSAT was developed. The method was validated with a subset of reservoirs in the Preto River Basin for which surface areas, shapes and depths were determined with ground-based survey measurements. The agreement between measured and the remotely sensed reservoir volumes was satisfactory, indicating that remotely-sensed images can be used for improved management of water in the Brazilian Savannah region. With the newly developed methods we found that the Preto River Basin’s 147 small reservoirs can store 19 × 10⁶ m³ of water at full capacity.     

岷江流域水库建设对水沙输移的影响

岷江作为长江上游重要支流,为川西和成都平原社会经济发展提供了重要支撑。相较于长江其他主要支流,岷江流域整体水电开发时间略晚。近年来,岷江流域水库建设工程不断增多,流域水沙情况开始变化。根据实测资料,运用水沙过程线法和径流量-输沙量双累计曲线法,初步分析岷江水库建设特点、水沙输移变化,以及二者之间的联系。结果表明:水库数量和总库容分别在1970年和2005年后有了较大的提升,水库建设的趋势是由干流深入到支流,虽然近年水库建设数量减少,但高坝大库逐渐增多;随着建坝技术水平的提高,逐渐由易建造的土坝变为筑坝难度高的其它坝型;由于水库调控能力、拦沙作用的增强,流域主汛期径流量、输沙量出现坦化现象,年径流量和年输沙量在1990年后均有减小趋势,且年输沙量减少的趋势更明显。近期高场站年输沙量变化与岷江水库建设有着一定的负相关关系,随着岷江流域水库总库容的进一步增大,这种相关关系增强,且在汛期体现得更为明显。     

梯级水库对澜沧江干流水温沿程变化的影响

21世纪以来,澜沧江流域开始兴建水电站,对整个澜沧江的生态环境将产生巨大影响。基于对澜沧江干流云南段进行3次沿程水温观测及水文历史数据,分析了澜沧江水温的沿程变化。采用插值法、数据均一化、显著性差异分析等方法分析了梯级水库对于澜沧江干流水温沿程变化的影响。通过分析发现:①建库前后澜沧江干流的全河段水温与纬度、高程呈明显的线性负相关关系;②从流域层面上来讲,澜沧江梯级水库的建设对澜沧江水温整体沿程变化无显著性影响。研究成果有助于从整个流域层面上认识水温沿程变化,从而对梯级水库建设下的水库群联合调度提供参考。     

长江水库群联合调度可能性分析

 由于长江大型水库建设步伐加快和流域经济社会的发展,迫切需要进行水库群联合调度,解决防洪、兴利和生态等问题。根据长江大型水库建设情况及水库特性,预测未来10年水库群库容规模,分别从防洪、兴利和生态等方面分析可调度能力、存在的问题。分析表明：虽然长江流域水库数量多,但由于长江水量大,可直接用于流域性调节的库容仍然有限,从调度可能性和运行机制等方面来看,目前比较有效的联合调度主要在防汛和应急调水方面,而解决生态、大面积的干旱和压咸等问题尚处在探索阶段,要解决流域范围内的抗旱、生态、河口压咸等问题必须采取包括水库联合调度在内的综合措施。     

Integrated Reservoir Management System for Adaptation to Climate Change: The Nakdong River Basin in Korea

This study begins with the premise that current reservoir management systems do not take into account the potential effects of climate change on optimal performance. This study suggests an approach in which multi-purpose reservoirs can adapt to climate change using optimal rule curves developed by an integrated water resources management system. The system has three modules: the Weather Generator model, the Hydrological Model, and the Differential Evolution Optimization Model. Two general circulation models (GCMs) are selected as examples of both dry and wet conditions to generate future climate scenarios. This study is using the Nakdong River basin in Korea as a case study, where water supply is provided from the reservoir system. Three different climate change conditions (historic, wet and dry) are investigated through the compilation of six 60 years long scenarios. The optimal rule curves for three multi-purpose reservoirs in the basin are developed for each scenario. The results indicate that although the rule curve for large-size reservoir is less sensitive to climate change, medium or small-size reservoirs are very sensitive to those changes. We further conclude that the large reservoir should be used to release more water, while small or medium-size reservoirs should store inflow to mitigate severe drought damages in the basin.     

安徽省小型水库管理体制改革实践与探讨

水库运行管理水平的提升有利于其功能的充分发挥。为进一步探索加强小型水库管理办法,总结了安徽省小型水库管理体制改革示范县创建活动取得的成果,提出以专业化管护服务机构统一负责域内小型水库管护任务的管理模式,用以工代赈方式吸纳农村劳动力充实管护队伍,促进工程所在地群众就业、增收,并对劳动力优选、劳务报酬发放、技能培训提出建议,对增加管理经费提出开发利用水库现有水、土资源的多渠道保障措施,供各级水行政主管部门参考。     

The Role of Small Reservoirs in a Water Scarcity Scenario: a Computational Approach

This paper presents the evaluation and management of water resources at the basin scale, focusing on small reservoirs. Due to a lack of knowledge on these untapped resources, a semiautomatic procedure for their surface area estimation is presented. Multispectral images from the Pleiades satellite were used to extract water bodies from a combination of different bands. In particular, the normalized difference water index (NDWI) was used to evaluate the presence or absence of water. This methodology was applied in a test area located in the upper Tiber River Basin. The performance for identifying and analysing small reservoirs was determined by comparing the satellite information with a reference database. The potential volume available from the investigated small reservoirs was compared with the water deficit derived from a decision support simulation model at the basin/subbasin scale, which studies water allocation for multipurpose uses. Five irrigation districts were analysed. For three of these districts, more than 60% of the annual deficit can be balanced with the volume stored in small reservoirs.

To date, water scarcity conditions have been increasingly frequent, so resilience in water resource management is a key requirement. Therefore, it is essential to evaluate the recovery and reuse of small reservoirs to strongly support water use, particularly irrigation and environmental uses.

     

乌江流域水资源、水质变化与水库建设关系分析

对乌江流域2001—2005年水资源与水环境质量的多项指标进行统计分析,并结合乌江流域梯级水电站建设,采用聚类分析的方法探究水库建设与水资源及水质变化的内在联系。结果表明:乌江流域降雨量、地表水资源量、年平均含沙量等指标年际变化很大;流域水质有逐渐恶化的趋势,主要污染区域在乌江上、中游地区的支流河段;各级水库的年末蓄水量与降雨量有关,与工农业用水量呈显著负相关;水库建设对流域的影响具有累积效应和滞后效应。     

Water quality monitoring: the basis for watershed management in the Oldman River Basin, Canada.

The Oldman River flows 440 km from its headwaters in south-western Alberta, through mountains, foothills and plains into the South Saskatchewan River. Peak flows occur in May and June. Three major reservoirs, together with more than a dozen other structures, supply water to nine irrigation districts and other water users in the Oldman basin. Human activity in the basin includes forestry, recreation, oil and gas development, and agriculture, including a large number of confined livestock feeding operations. Based on the perception of basin residents that water quality was declining and of human health concern, the Oldman River Basin Water Quality Initiative was formed in 1997 to address the concerns. There was limited factual information, and at the time there was a desire for finger pointing. Results (1998-2002) show that mainstem water quality remains good whereas tributary water quality is more of a challenge. Key variables of concern are nutrients, bacteria and pesticides. Point source discharges are better understood and better regulated, whereas non-point source runoff requires more attention. Recent data on Cryptosporidium and Giardia species are providing benefit for focusing watershed management activities. The water quality data collected is providing a foundation to implement community-supported urban and rural better management practices to improve water quality.     

Flood Control Operation of Reservoir Group Using Yin-Yang Firefly Algorithm

Flood control operation (FCO) of a reservoir is a complex optimization problem with a large number of constraints. With the rapid development of optimization techniques in recent years, more and more research efforts have been devoted to optimizing FCO problems. However, for solving large-scale reservoir group optimization problem, this is still a challenging task. In this work, a reservoir group FCO model is established with minimum flood volume stored in each reservoir and minimum peak flow of downstream control point during the dispatch process. At the same time, a flood forecast model for FCO of a reservoir group is developed by coupling Yin-Yang firefly algorithm (YYFA) with ε constrained method. As a case study, the proposed model is applied to a three-reservoir flood control system in Luanhe River Basin consisting of reservoirs, river channels, and downstream control points. Results show that optimal operation of three reservoirs systems can efficiently reduce the occupied storage capacity for flood control and flood peaks at downstream control point of the basin. The proposed method can be extended to FCO of other reservoir groups with similar conditions.

     

浅析黄河水资源的可持续管理战略

为实现“以黄河水资源的可持续利用,来保障黄河流域经济、社会、环境的可持续发展”,通过分析黄河水资源的特点与开发利用中面临的缺水形势严峻、部分地区用水浪费、水污染严重、中游干流河段水库调节能力不足、水资源管理水平亟待提高等主要问题,探讨了黄河流域可持续发展系统的特点及其该系统对黄河水资源可持续利用的主要影响、黄河水资源可持续利用指标体系的概念框架以及黄河水资源可持续利用的目标管理体系．     

Ensemble Based Forecasting and Optimization Framework to Optimize Releases from Water Supply Reservoirs for Flood Control

Water supply reservoir management is based on long-term management policies which depend on customer demands and seasonal hydrologic changes. However, increasing frequency and intensity of precipitation events is necessitating the short-term management of such reservoirs to reduce downstream flooding. Operational management of reservoirs at hourly/daily timescales is challenging due to the uncertainty associated with the inflow forecasts and the volumes in the reservoir. We present an ensemble-based streamflow prediction and optimization framework consisting of a regional scale hydrologic model forced with ensemble precipitation inputs to obtain probabilistic inflows to the reservoir. A multi-objective dynamic programming model was used to obtain optimized release strategies accounting for the inflow uncertainties. The proposed framework was evaluated at a water supply reservoir in the Hackensack River basin in New Jersey during Hurricanes Irene and Sandy. Hurricane Irene resulted in the overtopping of the dam despite releases made in anticipation of the event and resulted in severe downstream flooding. Hurricane Sandy was characterized by low rainfall, however, raised significant concerns of flooding given the nature of the event. The improvement in NSE for the Hurricane Irene inflows from 0.5 to 0.76 and reduction of the spread of PBIAS with decreasing lead times resulted in improvements in the forecast informed releases. This study provides perspectives on the benefits of the proposed forecasting and optimization framework in reducing the decision making burden on the operator by providing the uncertainties associated with the inflows, releases and the water levels in the reservoir.

     

农村小型水库功能退化分析及恢复对策

小型水库占我国水库总数96%以上,在地方防汛、灌溉、供水和养殖等方面地位重要且不可替代。因财政投入不足和疏于管护,农村小型水库功能快速退化,总体表现出淤积渗漏严重,蓄水能力低下;水质备受氮磷等营养物质污染,富营养化现象突出;水库出租养鱼后功能单一等特点。针对小型水库功能萎缩与退化的现状,从加强水文、水资源、水质等基础数据调查,依据供用水情况明确小型水库的核心功能及恢复目标,严控泥沙淤积与恢复兴利库容,污染阻控削减和增加水环境容量,发展生态养殖和防治生态过载以及鼓励投入与科学监管维护等方面提出了对策及建议,以期为农村小型水库水资源高效储蓄与可持续利用提供科学依据。     

新时期三门峡水库的地位和功能

三门峡水库投入运用以来，在确保黄河下游防洪、防凌安全等方面发挥了巨大的作用，在水库调度、机组抗磨蚀等方面取得了丰硕成果，为多泥沙河流水库如何长期保持有效库容探索出了一条成功之路。小浪底水库修建后，根据黄河治理开发规划及黄河下游洪水处理调度和水资源综合利用的要求，三门峡水库仍须承担相当繁重的任务：①按照小浪底水库设计要求，只有当小浪底、三门峡、故县、陆浑4座水库联合调度时，黄河下游才能达到千年一遇防洪标准。小浪底水库死库容淤积完后，需要三门峡水库配合运用的防洪库容将更大。②当黄河下游发生严重凌情时，小浪底正常运用后的库容不能满足下游防凌的要求，仍需要三门峡与小浪底两水库联合控制。③随着黄河流域经济的快速发展，三门峡水库将在未来的供水体系中占有十分重要的位置。④三门峡、小浪底和西霞院3座水利枢纽将组成梯级水库群，小浪底水库承上启下，发挥中心枢纽的作用，但小浪底水库库容也是有限的，一些问题仍需要三门峡水库配合才能得到解决。此外，三门峡水库建库初期，破坏了当地的自然环境，而投入运用40多年来，非汛期蓄水，汛期降低水位，经过自然的修复和人工的建设，在库区形成了独特的生态系统和自然环境，在库周形成了依托水库发展的社会经济模式，因此三门峡水库不仅承担着流域治理开发而赋予的任务，而且对库区自身的发展起着重要作用：①保护和改善库区湿地生态环境。②为库区沿岸工农业用水提供保障。③改善库区水质。④支撑三门峡市的发展。     

高坝水库放空要求及设施设计研究

高坝水库调节能力强,在流域梯级开发和防灾减灾中发挥重要作用,但其面临的风险也客观存在,一旦失事后果不堪设想。水库放空或降水位能力是经济社会发展新阶段对大坝风险防控和应急管理提出的新要求。本文给出水库放空的定义、目的及分类,系统阐述了放空水头比、放空库容比、库水位降速等水库放空能力评价指标,梳理了国内外对水库放空的要求,选取我国25座典型高坝水库进行放空能力分析。结果表明：高坝水库放空水头比介于17.5%～71.8%,均值为42.7%;放空库容比介于47.2%～99.2%,均值为81.7%;放空时间介于7.2～123 d,均值为42.7 d;库水降速介于0.71～9.03 m/d,均值为3.0 m/d。从实践来看,高坝水库放空能力受总库容、放空水位、坝型等工程特性参数影响,也受河流形态、河谷形状和库盆特点等因素影响。据此对水库放空设施设计中的入库流量、放空指标、启动条件和分级决策模式等关键问题进行了分析,对我国水利水电工程行业水库放空设施设计和应急管理有一定参考意义。     

1956-2009年延河水沙变化特征及其驱动力研究

分析降雨、人类活动等因子驱动下的流域水沙效应是流域管理的基础。本文采用移动平均法、累计距平法,线性回归统计等,分析了1956-2009年期间延河流域的降雨、径流和输沙量变化及其驱动因素。结果表明:延河流域降雨量与径流量、输沙量变化趋势基本一致,均可分为1956-1969年的基准期和1970年以后的3个时段的治理期等4个阶段。基准期三者均达到最大,治理期以输沙变化的时段性最为显著;且三者基本符合先大幅度下降(1970-1983年),然后明显上升(1984-1993年),再迅速下降(1994-2009年)的时段性。径流泥沙的时段性既是降雨量出现阶段性变化的结果,更是阶段性人类活动的水沙效应结果。整个治理期降雨和人类活动对减少径流的贡献比是60∶40,对减少泥沙的贡献比为30∶70;治理时段引起水沙变化的主要人类活动包括:1970-1983年的淤地坝、水库等水利设施建设大大减少水沙;1984-1993年的农业包产到户政策使得减水减沙幅度逐渐减少;1994年以来延河治理和退耕还林战略等极大地减少了流域径流泥沙。研究结果对延河流域管理实践有指导意义。