The Economic Impact of Water Evaporation Losses from Water Reservoirs in the Segura Basin,SE Spain

In this paper we assess the economic impact of evaporation losses from great dams (GDs) and on-farm agricultural water reservoirs (AWRs) in the semi-arid Segura River basin, SE Spain. Evaporation losses from water reservoirs reduce the high water use efficiency reached in agriculture by means of other techniques such as well-built water pipes or drip irrigation and have a substantial economic impact. Evaporation losses have been calculated using Class-A pan evaporation data and pan coefficients, whereas their economic impact has been assessed using an economic mathematical programming model that simulates land and water allocation in the different irrigated areas of the basin. Our results show that annual evaporation from GDs and AWRs represents 8.7% of the water currently available for irrigation in the Segura basin. The economic impact of such losses has been estimated in a reduction of 6.3% of the value of agricultural production and 5.4% of the farm net margin. As less water is effectively available for farmers the basin’s irrigated area is reduced in a 7.5%. This impact is greater, in both absolute and relative terms, in the areas accommodating the most intensive and profitable irrigated agriculture. The applied methodology and results could be useful to regional water agencies and collective irrigation schemes for future planning and management, including the assessment of alternatives for reducing evaporation from reservoirs.     

Socio-Economic Impact of Evaporation Losses from Reservoirs Under Past, Current and Future Water Availability Scenarios in the Semi-Arid Segura Basin

This study assesses evaporation losses from water reservoirs in the semi-arid Segura basin (south-east Spain), one of the most water stressed European catchments. These losses are evaluated from both the hydrologic and economic perspectives under different water availability scenarios that are based on water policy trends and climate change predictions. We take a multidisciplinary approach to the analysis, combining energy balance models to assess the effect of climate change on evaporation from water bodies, Class-A pan data and pan coefficients to determine evaporation loss on a regional scale, and non-linear mathematical programming modelling to simulate the economic impact of water use and allocation in the basin. Our results indicate that water availability could be reduced by up to 40 % in the worst-case scenario, with an economic impact in the 32–36 % range, depending on the indicator in question. The total annual evaporation loss from reservoirs ranges from 6.5 % to 11.7 % of the water resources available for irrigation in the basin, where evaporation from small reservoirs is more than twice that from large dams. The economic impact of such losses increases with water scarcity, ranging from 4.3 % to 12.3 % of the value of agricultural production, 4.0 % to 12.0 % of net margin, 5.8 % to 10.7 % of the irrigated area, and 5.4 % to 13.5 % of agricultural employment. Results illustrate the importance of evaporation losses from reservoirs in this region and the marked upward trend for future scenarios. Besides, they highlight the extent of the impact of climate change on future water resources availability and use in southern Europe.     

气候变化条件下叶尔羌流域水库蒸发变化分析

为了研究气候变化对水库水面蒸发的影响,以叶尔羌河流域为研究对象,选取气温、相对湿度以及风速作为主要气候影响因子,基于人工神经网络构建统计降尺度模型。对研究区在全球气候模式BCC-CSM1.1三种情景(RCP2.6,RCP4.5,RCP8.5)下2020s、2050s、2080s时段内的蒸发量进行了预测。结果表明:叶尔羌流域水库的未来蒸发量总体呈增加态势,蒸发量E_(RCP2.6)E_(RCP4.5)E_(RCP8.5);2020s时段内3种情景模式下所选取水库年平均蒸发量为1 922.4~2 337.9 mm,蒸发渗漏损失率为35.17%~36.40%。     

The change and prediction of temperature and precipitation in the Dawen River basin using the statistical downscaling model (SDSM)

In order to explore the climate change in the Dawen River basin,based on the data of six weather stations in the Dawen River basin from 1966 to 2017,Mann Kendall test and wavelet analysis were used to study the temperature and precipitation trends,mutations and cycles in the region.In addition,based on the three scenarios of RCP2.6,RCP4.5,and RCP8.5 under the CanESM2 model,SDSM was used to compare and analyze the future climate change of the Dawen River basin.The results revealed that:the annual mean temperature of the Dawen River basin had increased significantly since 1966 (p<0.01);in different scenarios,the spatial distribution of the projected maximum temperature,minimum temperature and precipitation will hardly change compared with that in history;the temperature and precipitation in the Dawen River basin will generally increase in the future.The rising trend of maximum and minimum temperature under the three scenarios is in the EP相似文献   

气候变化影响下黄河上游梯级水库群未来发电量预测

为分析气候变化影响下黄河上游大型水库入库来水过程及梯级发电量的时程变化规律,以黄河上游龙羊峡刘家峡梯级水库群为例,采用Mann-Kendall 突变检验方法对唐乃亥和小川水文序列进行突变识别,在此基础上构建了考虑融雪过程的HBV 水文模型,利用统计降尺度方法对CanESM2 和GFDL_ESM2G 两种气候模式3 种气候变化情景(RCP2. 6、RCP4. 5 和RCP8. 5) 下的降水、气温数据进行空间降尺度处理,并将其驱动水文模型预测未来入库来水过程,构建黄河上游梯级联合发电调度模型分析气候变化对未来发电调度过程的影响。结果表明:黄河上游径流序列突变年份集中于20 世纪80 年代,且2000 年之后径流量显著减少;气候变化将导致未来(2021—2050年)汛期6—9 月径流增加,非汛期径流显著减少;随着时间推移,不同气候变化情景下,龙羊峡和刘家峡两库的梯级发电量变化规律不同,RCP8.5 气候变化情景下,气候模式不确定性对其影响最大。     

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.     

A Tale of Two Dams: The Impact of Reservoir Management on Rural Depopulation in Central Spain

In rural areas, depopulation is mainly due to a lack of economic and employment opportunities. In this context, the reservoirs already built can be a source of socioeconomic development based on tourism and outdoor leisure activities. The condition for this development to materialize is that reservoir management considers these activities. In Central Spain, a process of rural depopulation has been generated in the municipalities around the reservoirs at the Upper Tagus River, as water management allows water transfers from the Tagus to the Segura River without taking into account regulations that prioritize and protect donor basin users. Through the comparison of reservoir water management and demographic data of two rural areas close to the reservoirs, this article reveals the direct relationship between reservoir management that enables recreational uses with its consequent socioeconomic development and the maintenance of the population in the territory. Consequently, reservoir water management based on the socioeconomic development of reservoir banks is necessary and a priority over transfers to another basin.

     

Assessing Impacts of Conservation Measures on Watershed Hydrology Using MIKE SHE Model in the Face of Climate Change

Climate change triggers changes in temperature, precipitation, evapotranspiration, etc. and has a significant impact on water resources in many regions. Considering the increasing scarcity of water as a result of climate change, conservation of water and groundwater recharge have become crucial factors for water resources planning and management. In this paper, an attempt is made to study the detailed hydrological behaviour of a treated watershed using physically based distributed hydrological modelling system MIKE SHE to assess the impact of conservation measures on watershed hydrology considering future climate change. Three hypothetical management scenarios are simulated for the period 2010–2040. RegCM4 regional climate model is used in the study for RCP 4.5 and RCP 8.5 scenarios. Detailed hydrological water balance is extracted for individual years from 1979 to 2009 to compare relevant components. The evaluation for base period shows 10.06% reduction in surface runoff and 11.33% enhancement in groundwater recharge. Further simulation with RCP 4.5 and RCP 8.5 scenarios show notable reduction in surface runoff and increase in groundwater recharge. The structures in the micro-watershed influence the surface runoff and increase infiltration into the soil, resulting in higher groundwater recharge. MIKE SHE simulations for various structures management scenarios establish the role of conservation measures in reducing surface runoff and enhancing groundwater recharge under substantial effect of climate change. The results will assist in decision-making on watershed development plans in quantitative terms, including planning for water conservation measures in the face of climate change.

     

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。     

Impact of Spatial Data Availability on Climate Change Prediction in the Weyib River Basin in Ethiopia

Impact of spatial data availability on the temperature and precipitation prediction characteristics of Weyib River basin in Ethiopia has been investigated using CMIP5-CanESM2 model for the RCP8.5, RCP4.5 and RCP2.6 scenarios. The objective of the present study is to characterize how future temperatures and precipitation prediction under CMIP5-CanESM2 model output varies against diverse averaged arbitrary spatial weather stations found in the basin. The statistical downscaling model tested and verified using the observed daily data for twelve, six and three averaged arbitrary spatial weather stations as well as for a single weather station was used to predict the future climate scenarios. The results revealed that the mean annual daily maximum and minimum temperature and precipitation for twelve, six and three arbitrary spatial stations have revealed an increasing trend in the upcoming periods until the end of the century. In single station analysis, the trend itself has changed from increasing trend to decreasing trend in case of maximum and minimum temperature. In case of precipitation, no visible trend has been observed in case of single station analysis. Therefore, the variation in amount and distribution of precipitation and temperature among the four averaged spatial stations in the same study area might affect the water resources and agriculture of the basin and also instead of using a single weather station to predict future climate variables for a particular study basin, it is more reliable using averages of numerous spatial weather stations data.     

基于冻土水文模拟的松花江流域水资源演变规律

为分析松花江流域水资源的演变规律,基于寒区水-热-氮素循环模型（the?water?and?energy?transfer?processes and?nitrogen?cycle?processes?model?in?cold?regions,WEP-N）和水资源评价方法,对径流发生突变的 1998 年前后（即 1999—2018 年和 1956—1998 年）进行比较,松花江流域年水资源总量减少 217.0 亿 m3,减幅达到 22.2%。其中, 地表水资源量减少是水资源总量减少的主要组分,占水资源总量减少的比例为 96.9%,不重复地下水资源减少量 占 3.1%。基于多因子归因分析方法分析可知,气候变化是松花江流域水资源减少的主要因素,对松花江流域全年 水资源总量、地表水资源量、不重复地下水资源量减少的贡献率分别为 81.6%、74.9%、286.6%,取用水的贡献率 分别为 18.4%、25.1%、－86.6%。从年内不同时期分析可知,非冻融期是全年水资源量减少的主要时期,占全年水 资源总量减少的 82.6%,冻融期占 17.4%。和北方的海河流域、黄河流域相比,水资源减少幅度和主要影响因素各 不相同,主要取决于气候变化和人类活动强度变化幅度的不同。与位于华北和西北的两大流域海河流域和黄河 流域对比,气候变化对松花江流域水资源衰减的影响与海河流域相当,明显大于黄河流域,而人类活动对松花江 流域水资源衰减的影响明显小于两大流域。     

Assessing Adaptability of Cyclic and Non-Cyclic Approach to Conjunctive use of Groundwater and Surface water for Sustainable Management Plans under Climate Change

Groundwater overdraft in many regions throughout the world has been threatening the sustainability of this valuable resource. It has been argued that climate change may contribute to the severity of the issue; hence “impact assessment” is being replaced by “adaptation,” which explores more adapting scenarios and approaches. This study explores the adaptability of the proposed cyclic and non-cyclic conjunctive use of groundwater and surface water resources in increasing groundwater sustainability while increasing the sustainability of water allocation to the agricultural sector under possible climate change scenarios. To simulate climate change in the study area, precipitation and temperature variables are extracted from the results of three global atmospheric circulation models (Ensemble, CMCC-CMS, MRI-CGCM3) under RCP2.6 and RCP8.5 greenhouse gas emission scenarios in the period of 2021–2031. Spatial downscaling is performed using the M5 decision tree algorithm. The Wavelet-M5 hybrid model is used to predict runoff values as a rainfall-runoff model. Also, the Kharrufa method is applied to calculate evaporation in the future seasons. The system's adaptability to climate change is examined using the multi-objective cyclic and non-cyclic conjunctive use of surface and groundwater models. The study reveals that cyclic operation strategy improves the conjunctive use system adaptability compared to the optimal operation strategy that employs the non-cyclic approach. In this study's case study, the improvement in groundwater sustainability index exceeds 27 percent over the non-cyclic conjunctive use strategy.

     

Impacts of climate change on water provisional services in Tungabhadra basin using InVEST Model

Water is one of the most important ecosystem services because it is essential for food and energy production. The Tungabhadra basin, located in peninsular India, has a variety of challenges, including inter-basin water-sharing issues, low agricultural productivity and value, and rising need for renewable energy production. The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) water yield model is used to analyze the consequences of climate change on water related services such as water yield and hydropower generation in the densely populated Tungabhadra basin. The impact of climate change on water supply services is studied for the period 1971–2000 as well as the future period 2021–2040. The model is calibrated using streamflow data collected at the Bawapuram gauge station in Telangana and there is a strong correlation between observed and simulated flow. The water yield for the entire basin declined by 33 and 50% under the Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios, respectively. The RCP 4.5 scenario reduces hydropower production and its Net Present Value (NPV) by 41 to 59%, whereas the RCP 8.5 scenario reduces production and NPV by 56 to 67%. The assessment of ecosystem services at the catchment scale revealed that the basin could be vulnerable to climate change due to a dramatic drop in ecosystem services. The methodology developed in this study can be applied to other river basins where quantifying ecosystem services is critical.     

气候环境变化对农业水利工程的影响——以新疆和田地区为例

通过对新疆和田地区近40年来气象与水文要素资料的研究分析,表明和田地区年平均气温呈上升趋势;同时和田河流域的降水量也呈增加趋势;平均相对湿度呈下降趋势;日照时数呈不明显的增加趋势;蒸发深总体呈减小趋势。和田地区气候变化对农业水利工程的影响有利也有弊,应该合理规划农业水利工程,在保障安全的前提下较好地发挥其作用。     

基于稳定同位素的策勒河流域山区河流蒸发损失估算

为探究昆仑山北坡山区流域水体蒸发损失垂直变化情况,基于2016年5-12月昆仑山北坡中段策勒河流域不同水体同位素数据,运用蒸发富集模型和稳定同位素（¹⁸O和²H）方法,研究了流域内不同水体的同位素时空变化特征,分析了策勒河流域的补给来源,并根据蒸发富集模型估算了流域内不同海拔地区同位素的蒸发损失。结果表明：流域内不同水体同位素的特征呈高山区贫化、荒漠区富集的趋势;策勒河河水与地下水存在密切的水力联系;策勒河流域在不同海拔的平均蒸发损失：高山区为24.99%、中山区为29.04%、荒漠区为35.00%。研究结果对理解区域水平衡及其对山区生态系统气候变化的响应具有重要意义。     

气候变化对嘉陵江流域水资源量的影响分析

 嘉陵江是长江的最大支流,流域面积约16万km2。针对2050,2100年不同的气候变化情景,选取较为不利的参数组合,根据降水、气温、湿度、风速、日照等气候要素的变化,建立潜在蒸发量模型计算流域的潜在蒸发量（ET0）,再根据流域内植被的蒸散发系数（Kc）,计算流域的面平均蒸散发量（ETc）。并利用流域面平均降水量减去径流深得到流域的实际蒸散发量,对计算的流域面平均蒸散发量进行验证。对不同的水平年利用降水的预测成果（气候变化情景不同具有不同的降水量预测成果）及计算流域的面平均蒸散发量,根据水量平衡模型分析计算气候变化对嘉陵江流域水量的影响。结果表明：不利条件下2050年年径流将减少23.0%～27.9%;2100将减少28.2%～35.2%;2050,2100年平均年径流分别相当于目前7年一遇和12年一遇的干旱年。由此说明,气候变化对流域内的水资源量影响十分显著。      

Optimal water allocation at different levels of climate change to minimize water shortage in arid regions (Case Study: Zayandeh-Rud River Basin,Iran)

Climate change is one of the most important factors influencing the future of the world's environment. The most important impacts of climate change are changes in water supply and demand in different regions of the world. In this study, different climate change patterns in two RCP4.5 and RCP8.5 emission scenarios (RCP: Representative Concentration Pathway), were adopted for the Zayandeh-Rud River Basin, Iran, through weighting of GCMs (General Circulation Models). These climate change patterns are including ideal, medium, and critical patterns. Using the LARS-WG model (Long Ashton Research Station Weather Generator), the outputs of the GCMs were downscaled statistically and the daily temperature and precipitation time series were generated from 2020 to 2044. Then, based on this information, the inflow volume into the Zayandeh-Rud Reservoir was predicted by the IHACRES model (Identification of unit Hydrograph and Component flows from Rainfall, Evaporation and Streamflow) and the agricultural water demand was also estimated based on future evapotranspiration. Finally, using GAMS (General Algebraic Modeling System) software, water resources in this basin were allocated based on the basic management scenario (B) and the water demand management scenario (D). The results showed that the average monthly temperature will increase by 0.6 to 1.3 °C under different climate change patterns. On the other hand, on the annual basis, precipitation will decrease by 6.5 to 31% and inflow volume to the Zayandeh-Rud Reservoir will decrease by 21 to 38%. The results also showed that the water shortages based on the baseline management scenario (B) will be between 334 and 805 MCM (Million Cubic Meters). These range of values varies between 252 and 787 MCM in the water demand management scenario (D). In general, the water shortage can be reduced in the Zayandeh-Rud River Basin with water demand control, but complete resolution of this problem in this region requires more integrated strategies based on a sustainable development, such as a fundamental change in the cropping pattern, prevention of population growth and industrial development.     

基于Copula函数的气候变化下洪水峰量联合分析

为研究气候变化对北江流域洪水特征发生频率的影响,采用分位数映射(Quantile Mapping,QM)后处理方法校正BCC_CSM1.1气候模式2种情景(RCP4.5和RCP8.5)下的气候数据,用于SWAT模型模拟历史(1965—2010年)和未来(2030—2064年、2065—2099年)的北江流域径流量,并采用单变量分析法和基于Copula函数的双变量联合分析法分别对各时期年最大洪峰流量Q和年最大7 d洪量W进行对比分析。结果表明:除RCP8.5下2065—2099年的W外,重现期(T≥50 a)越大,气候变化对Q和W的影响越大; RCP4.5下气候变化对Q和W的影响较RCP8.5下大;2种未来情景下,气候变化对Q的影响均大于对W的影响;对于同一重现期,双变量联合分析法推求的洪水特征设计值较单变量分析法的偏安全。该研究结合了气候变化和双变量联合分析,对变化环境下的洪水风险评价与管理具有一定的参考价值。     

Climate change impact on water quality in the integrated Mahabad Dam watershed-reservoir system

Climate change, besides global warming, is expected to intensify the hydrological cycle, which can impact watershed nutrient yields and affect water quality in the receiving water bodies. The Mahabad Dam Reservoir in northwest Iran is a eutrophic reservoir due to excessive watershed nutrient input, which could be exacerbated due to climate change. In this regard, a holistic approach was employed by linking a climate model (CanESM2), watershed-scale model (SWAT), and reservoir water quality model (CE-QUAL-W2). The triple model investigates the cumulative climate change effects on hydrological parameters, watershed yields, and the reservoir’s water quality. The SDSM model downscaled the output of the climate model under moderate (RCP4.5) and extreme (RCP8.5) scenarios for the periods of 2021–2040 and 2041–2060. The impact of future climate conditions was investigated on the watershed runoff and total phosphorus (TP) load, and consequently, water quality status in the dam’s reservoir. The results of comparing future conditions (2021–2060) with observed present values under moderate to extreme climate scenarios showed a 4–7% temperature increase and a 6–11% precipitation decrease. Moreover, the SWAT model showed a 9–16% decline in streamflow and a 12–18% decline in the watershed TP load for the same comparative period. Finally, CE-QUAL-W2 model results showed a 3–8% increase in the reservoir water temperature and a 10–16% increase in TP concentration. It indicates that climate change would intensify the thermal stratification and eutrophication level in the reservoir, especially during the year’s warm months. This finding specifies an alarming condition that demands serious preventive and corrective measures.     

南水北调中线水源区与海河受水区丰枯遭遇研究

基于常用的趋势检验方法,对南水北调中线水源区和海河受水区降水序列进行趋势诊断,据此对其变化趋势进行了识别;基于历史实测和未来气候模式降水数据,通过构建边缘分布模型和Copula联合分布模型,来描述降水序列的独立结构,用于定量评估气候变化对水源区和海河受水区降水丰枯遭遇的影响。研究结果表明:过去55 a水源区和海河受水区降水量呈现为不显著的下降趋势;在气候变化RCP4.5和RCP8.5情景下,水源区与海河受水区降水量的丰枯遭遇概率均呈现为增加的趋势,调水有利组合降水量遭遇概率平均分别增加了3.58%和5.80%;同枯遭遇概率均小于30%,说明工程实施调水的可能性。对气候变化影响下的丰枯遭遇开展研究,可为南水北调中线工程的正常运行和水资源调度提供理论参考。