Assessment of Hydrological Drought Revisited

A variety of indices for characterising hydrological drought have been devised which, in general, are data demanding and computationally intensive. On the contrary, for meteorological droughts very simple and effective indices such as the Standardised Precipitation Index (SPI) have been used. A methodology for characterising the severity of hydrological droughts is proposed which uses an index analogous to SPI, the Streamflow Drought Index (SDI). Cumulative streamflow is used for overlapping periods of 3, 6, 9 and 12 months within each hydrological year. Drought states are defined which form a non-stationary Markov chain. Prediction of hydrological drought based on precipitation is also investigated. The methodology is validated using reliable data from the Evinos river basin (Greece). It can be easily applied within a Drought Watch System in river basins with significant storage works and can cope with the lack of streamflow data.     

Use of climate scenarios to aid in decision analysis for interannual water supply planning

This work addresses the issue of climate change in the context of water resource planning on the time scale of a few years. Planning on this time scale generally ignores the role of climate change. However, where the climate of a region has already shifted, the use of historical data for planning purposes may be misleading. In order to test this, a case study is conducted for a region, the Australian Capital Territory, where long term drought is raising concerns of a possible climate shift. The issue is cast in terms of a particular planning decision; the option to augment water supply in the next few years to hedge against the drought persisting. A set of climate scenarios are constructed for the region corresponding to the historical climate regime and to regimes where progressively greater levels of change are assumed to have already taken place (5%, 10%, 20% reductions in mean rainfall). Probabilities of the drought persisting are calculated for each of the scenarios. The results show substantial increases in the probability of the drought persisting for even moderate reductions in mean rainfall. The sensitivity of the decision to augment supply to the scenario results depends ultimately on the planners tolerable thresholds for the probability of the drought persisting. The use of different scenarios enables planners to explore the sensitivity of the decision in terms of their risk tolerance to ongoing drought and to their degree of belief in each of the scenarios tested.     

Temporal changes in the remote sensing reflectance at Lake Vänern

The Aerosol Robotic Network - Ocean Color (AERONET-OC) instrument located at the Pålgrunden site in Lake Vänern provides values of remote sensing spectral reflectance R_RS(λ) since 2008. These in situ R_RS(λ) indicated a temporal increase from 2015 at center-wavelengths in the green and red spectral regions. To investigate the environmental and climate processes responsible for this increase, water color trends in Lake Vänern were analyzed considering in situ limnological measurements, meteo-climatic quantities and additionally satellite-derived data products from the Moderate Resolution Imaging Spectroradiometer on board the Aqua platform (MODIS-A). Satellite ocean color R_RS(λ) data assessed against in situ R_RS(λ) from the Pålgrunden site showed satisfactory agreement at a number of spectral bands. Relying on these validation results, comprehensive statistical analysis were performed using MODIS-A R_RS(λ). These indicated periodical changes between 2002 and 2021 with clear minima occurring between 2010 and 2013. The complementary analyses of temporal changes characterizing limological and meteo-climatic quantities, and also relationships between these quantities and R_RS(λ), indicated the existence of complex and concurrent bio-geochemical processes influencing water color in Lake Vänern. In particular, significant correlations were observed between R_RS(λ) and turbidity, and also between R_RS(λ) and total biovolume. Additionally, an early warming of Lake Vänern surface waters was identified since spring 2014. This occurrence could potentially affect the vertical mixing and water exchange between turbid coastal and pelagic waters with implications for phytoplankton phenology.     

A Profile of the Submarine Springs in Lebanon as a Potential Water Resource

This is an overview of the submarine springs occurring along the coast of Lebanon, and the associated geological, hydrogeological, and hydrological characteristics of their terrestrial catchment areas. Emphasis is placed on springs in the Chekka Bay in North Lebanon because of their voluminous discharge, and their importance as a potential source of water. Tapping and exploiting the larger springs along the entire coast would yield an estimated 650 Mm³/yr of fresh water and would certainly help to alleviate the acute water shortage anticipated in the foreseeable future. However, the associated ecological and socio-economic impacts must be considered alongside the beneficial aspects. Such projects are essential to meet the increasing water demands in Lebanon and the region.     

山西水旱灾害及减轻灾害的对策

本文分析了山西水旱灾害特点及其成因，并提出了减轻灾害的对策，主要有加快河道综合治理，加强城市防洪治理，病险水库除险加固，灌区续建配套、污水资源化、开辟新水源等工程措施以及完善水法规体系、建立健全水旱灾害预警预报体系、防洪优化调度的实施等非工程措施。     

Development and Testing of Drought Indicators

Numerous definitions of droughts which are based on different climatological time series have been in use. In this paper, the development of drought indicators by using different time series is described. These drought indicators were developed for use by the Department of Natural Resources in the State of Indiana, U.S.A. The second part of the study deals with an analysis of the consistency of results obtained by using different time series, in order to select two or three of the commonly available series for drought analysis. Past drought data are used to test the performance of the drought indicators. As a result of this study, three month precipitation, monthly river flow and the Palmer Hydrologic Drought Index series are recommended for operational use.     

Optimal Water Resources Management: Case of Lower Litani River, Lebanon

The pressures of human population and patterns of development frequently jeopardize the integrity of river systems worldwide. An integrated approach to water resources management is essential, particularly in developing countries. This study presents the results of the water resources optimization conducted for the Lower Litani River Basin in Lebanon. The overall aim of the project is to develop, test, and critically evaluate an innovative approach to water resources management in the Mediterranean region. The method explores the ways in which multiple environmental, economic, and social benefits can be achieved through integrated management of water resources. The Water Resources Model was utilized to assess the efficiency of the baseline model scenario and for the optimization process of the different scenarios of the Litani Lower Basin. Strengths, weaknesses, opportunities and threats analysis was applied in order to derive the objectives and constraints. Results revealed that the potential retained scenarios aim at decreasing water consumption and demand, losses, and return flow. These scenarios mainly include the shift to drip irrigation, awareness campaigns, and losses control in domestic supply pipes. Other retained scenarios having a higher shortfall rely on the use of the Channel concrete lining to decrease losses and return flow, in addition to the awareness campaigns in both domestic and irrigation sectors, and less consumptive/more efficient irrigation methods such as sprinkler and drip irrigation at variable application percentages. Hence, most of the interventions or measures proposed are generally not costly and can be implemented.     

Climate Variability Influences on Hydrological Responses of a Large Himalayan Basin

The hydrological cycle, a fundamental component of climate is likely to be altered in important ways due to climate change. In this study, the historical daily runoff has been simulated for the Chenab River basin up to Salal gauging site using a simple conceptual snowmelt model (SNOWMOD). The model has been used to study the impact of plausible hypothetical scenarios of temperature and rainfall on the melt characteristics and daily runoff of the Chenab River basin. The average value of increase in snowmelt runoff for T + 1°C, T + 2°C and T + 3°C scenarios are obtained to be 10, 28 and 43%, respectively. Whereas, the average value of increase in total streamflow runoff for T + 1°C, T + 2°C and T + 3°C are obtained to be 7, 19 and 28%, respectively. Changes in rainfall by −10 and + 10% vary the average annual snowmelt runoff over the T + 2°C scenario by −1% and + 1% only. The result shows that melt is much more sensitive to increase in temperature than to rainfall.     

Probabilistic Characteristics of Drought Propagation from Meteorological to Hydrological Drought in South Korea

Water Resources Management - A reliable understanding of propagation from meteorological to hydrological drought is necessary for accurate forecasting of hydrological droughts. Our current...     

运城市1990—1999年旱灾的回顾与反思

本文回顾了1990－1999年发生的旱灾，据此提出今后的抗旱减灾对策。     

Streamflow and Hydrological Drought Trend Analysis and Forecasting in Cyprus

The persistent water shortage in Cyprus has been alleviated by importing freshwater from neighbouring countries, and severe droughts have been met with financial reimbursement from the EU at least twice. The goal of this research is to investigate and perform short-term forecasting of both streamflow and hydrological drought trends over the island. Eleven hydrometric stations with a 34-year common record length of the mean daily discharge from 10/1979 to 09/2013 are used for this purpose, with the relevant upstream catchments considered to represent pristine conditions. The Streamflow Drought Index (SDI) successfully captures the hydrological drought conditions over the island, and the performance of the index is validated based on both the historic drought archives and results from other drought indices for the island. The Mann–Kendall (M-K) test reveals that the annual and seasonal time series of the discharge volumes always illustrate a decreasing but insignificant trend at a significance level of a?=?0.05; additionally, the decrease per decade in the average annual streamflow volume based on Sen’s slope statistic is approximately ?9.4%. The M-K test on the SDI reveals that drought conditions intensified with time. Ten autoregressive integrated moving average (ARIMA) models are built and used to forecast the mean monthly streamflow values with moderate accuracy; the best ARIMA forecast model in each catchment is derived by comparing two model-performance statistical measures for the different (p,d,q) model parameters. The predicted discharge values are processed by the SDI-3 index, revealing that non-drought conditions are expected in most catchments in the upcoming three months, although mild-drought conditions are anticipated for catchments 7, 8 and 9.     

Regional Water Balance and Economic Assessment as Tools for Water Management in Coastal Lebanon

The Lebanese coast is highly subject to seawater intrusion and groundwater deterioration. The study is carried out in Byblos district (Jbeil Caza) 35 km north of Beirut. It aims to investigate the seawater intrusion, to determine the regional water balance of the region and finally to estimate the economic value of that water for agricultural use. The monitoring of the aquifer was achieved through samples from different wells chosen randomly. As for the regional water balance, it was determined with use of a GIS model. The economic evaluation was carried out, using the contingent valuation method to estimate the willingness to pay of farmers to contribute to the improvement of groundwater quality; two alternative scenarios were proposed and compared with the current situation. The annual regional water balance is positive, which means that the region is rich in water. The monitoring results show that the coastal part of the region is slightly contaminated by seawater intrusion due to the excess of pumping from the aquifer. The economic evaluation estimated that farmers would contribute by 102 US$ yr^− 1 for the first proposal and 166.67 US$ yr^− 1 for the second.     

呼伦湖水生态环境遥感监测及其对气候变化的响应

以位于内蒙古的第一大湖-呼伦湖为研究对象,综合应用RS、GIS等现代分析技术手段,通过解译该区1973、1975、1986～2009年近36a的MSS、TM、ETM遥感影像,实现了呼伦湖湖泊水位、面积的遥感动态监测,并建立了关系模型：研究发现呼伦湖面积在1999年达到了1959年以来的最大水面面积2106．95km2后开始骤然下降到2009年的最低水面面积1813．69km2。以24．44km2／a的速度减少了293．26km2,水面面积比1999年最大面积时减少了近14％。水位高程自1999年的最高水位下降了3．94m,是呼伦湖平均水深（9m）的39．4％。收集、整理了呼伦湖及上游流域4个气象站点、3个水文站点近52a的气象、水文资料。分析了呼伦湖区域尺度内的水热状况变化,发现研究区域温度升高。降水呈波动性减少．并且在1999年后温度和降水的变率增大,是呼伦湖面积减小、水位下降的主要原因。最后．分析了气候变化对呼伦湖生态环境的影响效应。并建立了湖泊水位和降水、气温等气象因子以及径流量之间的关系模型．研究可为寒旱区湖泊水环境管理提供参考。     

山西省连续三年旱灾的回顾与思考

本文综述了山西 1997、1998、1999三年旱灾 ,分析了旱灾发生的原因 ,并提出了几条对策     

辽宁省干旱分析与抗旱减灾对策

指出辽宁省干旱发生的自然规律和特点,分析了干旱产生的经济社会原因,有针对性地提出了相应的对策,为辽宁省抗旱减灾提供参考.     

抗旱信息网络在防旱减灾领域的建设与完善

本文介绍了现有抗旱信息网络的建设情况，分析了运行当中存在的问题，提出了完善抗旱信息网络的几条对策。     

Streamflow Drought Severity Analysis of Betwa River System (India)

Streamflow appraisal in time and space particularly in semi arid and dry sub humid regions has vital importance in the formulation of round the year plan of water uses comprising domestic & industrial water supply, irrigation scheduling, reservoir operation, in-stream flow maintenance etc. Drought severity analysis including the estimation of flow availability, drought duration, and deficit volume etc. was carried out using the 20–42 years (1960–2001) 10-daily streamflow data of five sites on the Betwa River system and. independent streamflow drought events were described by pooling the data, and severity of an independent drought event classified using a new drought severity index (DSIe) defined as a function of (1) the ratio of deficit flow volume to corresponding volume at the truncation level and (2) the ratio of duration of deficit flow to the maximum possible duration of the independent streamflow drought event. The study found that the upper reaches of river course were more prone to severe droughts than were the lower reaches. The drought events starting during August−November were more likely to be severe drought events than those in the other months.     

山西省抗旱决策支持系统建设

山西省抗旱决策支持系统是以现代信息技术为基础、对旱情进行实时／准实时监测的系统，根据灾情预测做出决策，合理调配水资源，减少灾害损失。本文论述了建设山西省抗旱决策支持系统的必要性、可行性和将要采取的技术路线，以及该系统实现后的功能。     

A critical assessment of a proposed public private partnership (PPP) for the management of water services in Lebanon

Public Private Partnerships (PPPs) are increasingly heralded as an innovative policy intervention in the context of critical urban infrastructure services where outright privatization and loss of control are considered unacceptable. This paper assesses a proposed PPP for the management of water services in the Lebanese capital, Beirut. Although the city of Beirut and its suburbs are considered as the center of social, economic, and political activities in the country, safe drinking water is not accessible to all the population of the city in view of the current economic crisis and the high level of urbanisation. A PPP is viewed as a promising solution to the water supply problem, especially in poor and suburban areas. After introducing PPPs and the rationale behind invoking private sector participation, this paper assesses the potential promise of different forms of PPPs in the context of the economic and institutional framework of water management in the Greater Beirut Area (GBA).     

Linking Drought Indicators to Policy Actions in the Tagus Basin Drought Management Plan

One crucial aspect of drought management plans is to establish a link between basin drought state and management actions. Basin state is described by a drought indicator system that includes variables like precipitation, streamflow, reservoir inflow, reservoir storage and groundwater piezometric levels. Basin policy consists on a catalogue of management actions, ranging from enforcing demand reduction strategies to establishing priority of users to allocate scarce water or approving emergency works. In this paper, the methodology applied in the Tagus Basin Drought Management Plan to link operational drought indicators to policy actions in regulated water supply systems is presented. The methodology is based on the evaluation of the probability of not being able to satisfy system demands for a given time horizon. A simplified model of every water resources system in the basin was built to evaluate the threshold of reservoir volume that is required to overcome the drought situation without deficit. For each reservoir level, a set of policy actions is proposed with the goal of guaranteeing essential demands during drought conditions. The methodology was validated with a simulation of system behavior for 60 years of historic streamflow series, finding acceptable results in most systems.