Estimation of future water resources of Xiangjiang River Basin with VIC model under multiple climate scenarios

Variation trends of water resources in the Xiangjiang River Basin over the coming decades have been investigated using the variable infiltration capacity(VIC) model and 14 general circulation models'(GCMs') projections under the representative concentration pathway(RCP4.5) scenario. Results show that the Xiangjiang River Basin will probably experience temperature rises during the period from 2021 to2050, with precipitation decrease in the 2020 s and increase in the 2030 s. The VIC model performs well for monthly discharge simulations with better performance for hydrometric stations on the main stream of the Xiangjiang River than for tributary catchments. The simulated annual discharges are significantly correlated to the recorded annual discharges for all the eight selected target stations. The Xiangjiang River Basin may experience water shortages induced by climate change. Annual water resources of the Xiangjiang River Basin over the period from 2021 to 2050 are projected to decrease by 2.76% on average within the range from-7.81% to 7.40%. It is essential to consider the potential impact of climate change on water resources in future planning for sustainable utilization of water resources.     

模糊神经网络水文预报模型在洺河流域的应用

本文选取雨强距离指数(IPD)及其他有关参数等作为自适应神经模糊推理系统(ANFIS)水文预报模型的输入,提出雨强距离指数的定义及其目的和意义。为剖析雨强距离指数在水文预报模型中的应用,分别建立不包含雨强距离指数的模型A与包含该指数的模型B进行对比评价。结果表明,将雨强距离指数作为ANFIS水文预报模型的输入能够提高模型的预报精度。     

Initiatives to clarify mechanisms of hydrological evolution in human-influenced Yellow River Basin

Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in China. It is necessary to investigate the impacts of climate change and human activities on hydrological evolution and disaster risk from a holistic perspective of the basin. This study developed initiatives to clarify the mechanisms of hydrological evolution in the human-influenced Yellow River Basin. The proposed research method includes: (1) a tool to simulate multiple factors and a multi-scale water cycle using a grid-based spatiotemporal coupling approach, and (2) a new algorithm to separate the responses of the water cycle to climate change and human impacts, and de-couple the eco-environmental effects using artificial intelligence techniques. With this research framework, key breakthroughs are expected to be made in the understanding of the impacts of land cover change on the water cycle and blue/green water redirection. The outcomes of this research project are expected to provide theoretical support for ecological protection and water governance in the basin.     

Analysis of the effect of climate change on the Nakdong river stream flow using indicators of hydrological alteration

This study models the effect of climate change on runoff in southeast Korea using the TANK conceptual rainfall-runoff model. The results are assessed using the indicators of hydrological alteration (IHA) developed by U.S. Nature Conservancy. Future climate time series are obtained by scaling historical series, provided by four global climate models (GCMs, IPCC, 2007) and three greenhouse gas (GHG) emissions scenarios (IPCC, 2000), to reflect a maximum increase of 3.6 °C in the average surface air temperature and 33% in the annual precipitation. To this end, the spatio-temporal change factor method is used, which considers changes in the future mean seasonal rainfall and potential evapotranspiration as well as the daily rainfall distribution. In this study, the variance range for precipitation is from +3.55% to +33.44% compared to the present for years between 2071 and 2100. The variance range for the daily mean temperature is estimated between +1.59 °C and +3.58 °C. Although the simulation results from different GCMs and GHG emissions scenarios indicate different responses of the flows to the climate change, the majority of modeling results show that there will be more runoff in southeast Korea in the future. According to the analysis results, the predicted impacts of hydrological alteration caused by climate change on the aquatic ecosystem are as follows: 1) an increase in the availability of aquatic ecosystem habitats in Nakdong River in future summers and winters, 2) an increase in stress on the aquatic ecosystem due to extremely high stream flow, 3) an increase in the stress duration of flood events for the Nakdong River downstream and 4) an increase in aquatic ecosystem stress caused by rapid increases or decreases in stream flow.     

基于Delta方法的淮河流域气候变化预测分析

为了预测气候变化对区域水文要素变化的影响,以淮河流域蚌埠以上区域为例,利用全球气候模式CSIRO和HadCM3,分别预测了同一情景下,淮河流域3个未来时段的降雨和温度变化。通过Delta变换对未来3个阶段的数据进行降尺度处理,运用曲线拟合的方法提出了蒸发函数模型。将预测出的气温作为蒸发函数模型的输入因子,模拟了淮河流域未来的蒸发过程。结果表明, 该区域未来时段的降雨、气温和蒸发量均比历史观测值有所上升。     

基于HBV的黑河流域径流对气候变化的响应

黑河流域是我国西北干旱区内陆河研究的代表性流域,研究未来气候变化对黑河流域山区径流的定量影响,对干旱区水资源规划设计、开发利用和保护管理具有重要意义。采用HBV-light模型,首先根据实测径流数据验证了该模型在黑河流域上游的适用性,然后拟定25种气候变化情景模式,模拟气温与降水变化对径流的定量影响。结果表明:(1)当气温保持不变时,降水增加会造成年径流增加;而当降水维持不变时,气温升高将导致年径流减少。(2)关于径流年内分布,气温变化与6~9月份的径流呈负相关关系,而与4月份的径流呈显著正相关关系;降水变化与径流呈明显的正相关关系;年径流与年内分配均表现为对于降水变化的敏感性高于气温变化。(3)未来气候变化有助于缓解黑河流域水资源短缺的现状。     

Forecasting impacts of climate change on Great Lakes surface water temperatures

Temperature influences the rates of many ecosystem processes. A number of recent studies have found evidence of systematic increases in Great Lakes surface water temperatures. Our study aims to construct empirical relationships between surface water temperatures and local air temperatures that can be used to estimate future water temperatures using future air temperatures generated by global climate models. Remotely sensed data were used to model lake-wide average surface water temperature patterns during the open-water period in Lakes Superior, Huron, Erie, and Ontario. Surface water temperatures typically exhibit linear warming through the spring, form a plateau in mid-summer and then exhibit linear cooling in fall. Lake-specific warming and cooling rates vary little from year to year while plateau values vary substantially across years. These findings were used to construct a set of lake-specific empirical models linking surface water temperatures to local air temperatures for the period 1995–2006. Hindcasted whole-lake water temperatures from these models compare favourably to independently collected offshore water temperatures for the period 1968–2002. Relationships linking offshore water temperatures to inshore water temperatures at specific sites are also described. Predictions of future climates generated by the Canadian Global Climate Model Version 2 (CGCM2) under two future greenhouse gas emission scenarios are used to scope future Great Lakes surface water temperatures: substantial increases are expected, along with increases in the duration of summer stratification.     

Human and climate impacts on Columbia River hydrology and salmonids

The Columbia River had until recently the world's largest Chinook salmon runs. Restoration of the system's severely decimated runs requires understanding changes in the hydrologic variables (e.g. flow and sediment transport) important to salmonids. We describe here methods to distinguish the human and climate‐induced contributions to Columbia River hydrologic processes relevant to the crucial seaward spring migration of juveniles through the tidal river and estuary. Flow regulation has caused most of the decrease in peak flow and sediment transport; it has contributed to changes in spring freshet timing. Climate change has reduced peak and average flows and sediment transport, changing spring‐freshet timing by several weeks. Irrigation diversion has reduced the annual average flow as much as climate change. A better understanding of historical changes in hydrologic processes entailed in this paper tells us how management and climate have changed the Columbia River system over time. The separation of the climate and anthropogenic influences used here may assist in policy analyses and strategies aimed at restoration of the Columbia River endangered salmonids, and in management of other systems. Copyright © 2010 John Wiley & Sons, Ltd.     

Comparative evaluation of impacts of climate change and droughts on river flow vulnerability in Iran

Rivers in arid and semi-arid regions are threatened by droughts and climate change. This study focused on a comparative evaluation of the impacts of climate change and droughts on the vulnerability of river flows in three basins with diverse climates in Iran. The standardized precipitation-evapotranspiration index (SPEI) and precipitation effectiveness variables (PEVs) extracted from the conjunctive precipitation effectiveness index (CPEI) were used to analyze the drought severity. To investigate hydrological droughts in the basins, the normalized difference water index (NDWI) and the streamflow drought index (SDI) were calculated and compared. The effects of droughts were assessed under various representative concentration pathway (RCP) scenarios. Changes in the number of wet days and precipitation depth restricted hydrological droughts, whereas an increasing number of dry days amplified their severity. The projected increases in dry days and precipitation over short durations throughout a year under future climate scenarios would produce changes in drought and flood periods and ultimately impact the frequency and severity of hydrological droughts. Under RCP 4.5, an increase in the frequencies of moderate and severe meteorological/hydrological droughts would further affect the Central Desert Basin. Under RCPs 2.6 and 8.5, the frequencies of severe and extreme droughts would increase, but the drought area would be smaller than that under RCP 4.5, demonstrating less severe drought conditions. Due to the shallow depths of most rivers, SDI was found to be more feasible than NDWI in detecting hydrological droughts.     

气候变化和人类活动对洮河输沙量变化的影响分析

根据洮河代表水文站近60年的输沙量资料,分析了洮河输沙量变化规律以及气候变化和人类活动对洮河输沙量变化的影响。结果表明:(1)洮河多年平均输沙量为2 295万t,输沙量从1990年开始呈明显递减并且有继续减少的趋势;(2)洮河各代表站输沙量均发生显著突变,突变年份发生在20世纪80年代末和90年代中上期,输沙量突变后比突变前有明显减少;(3)气候变化和人类活动共同影响下洮河输沙量呈减少趋势。总体上,气候变化对输沙量变化的影响要远小于人类活动的影响,20世纪90年代以前气候变化对输沙量的变化影响起主导作用,90年代以后人类活动的影响起主导作用。     

大尺度分布式水文模型VIC在嘉陵江流域径流模拟中的应用

大尺度分布式流域水文模型是目前评价流域环境变化的重要工具,以嘉陵江流域为研究对象,构建了嘉陵江流域大尺度分布式VIC模型(Variable Infiltration Capacity,VIC model),利用Maryland大学的全球1 km×1 km土地覆盖数据,同时参考LDAS(Land Data Assimilation System)成果,建立了嘉陵江流域VIC模型的参数库,通过4个水文站以上流域的水文模拟试验,结果表明建立的VIC模型能有效地模拟嘉陵江流域各典型站的日、月径流过程,模拟的水量平衡误差在5%以内,日径流过程模拟的确定性系数均在70%以上,月径流过程模拟的确定性系数超过90%。该模型可以用来分析环境变化对嘉陵江流域水资源及洪水过程的影响。     

Analysis and prediction of reference evapotranspiration with climate change in Xiangjiang River Basin,China

Reference evapotranspiration(ET_0) is often used to estimate actual evapotranspiration in water balance studies. In this study, the present and future spatial distributions and temporal trends of ET_0 in the Xiangjiang River Basin(XJRB) in China were analyzed. ET_0 during the period from1961 to 2010 was calculated with historical meteorological data using the FAO Penman-Monteith(FAO P-M) method, while ET_0 during the period from 2011 to 2100 was downscaled from the Coupled Model Intercomparison Project Phase 5(CMIP5) outputs under two emission scenarios, representative concentration pathway 4.5 and representative concentration pathway 8.5(RCP45 and RCP85), using the statistical downscaling model(SDSM). The spatial distribution and temporal trend of ET_0 were interpreted with the inverse distance weighted(IDW)method and Mann-Kendall test method, respectively. Results show that:(1) the mean annual ET_0 of the XJRB is 1 006.3 mm during the period from 1961 to 2010, and the lowest and highest values are found in the northeast and northwest parts due to the high latitude and spatial distribution of climatic factors, respectively;(2) the SDSM performs well in simulating the present ET_0 and can be used to predict the future ET_0 in the XJRB; and(3) CMIP5 predicts upward trends in annual ET_0 under the RCP45 and RCP85 scenarios during the period from 2011 to 2100.Compared with the reference period(1961e1990), ET_0 increases by 9.8%, 12.6%, and 15.6% under the RCP45 scenario and 10.2%, 19.1%, and27.3% under the RCP85 scenario during the periods from 2011 to 2040, from 2041 to 2070, and from 2071 to 2100, respectively. The predicted increasing ET_0 under the RCP85 scenario is greater than that under the RCP45 scenario during the period from 2011 to 2100.     

气候变化对乌裕尔河流域水文特性的影响

对两参数月水量平衡模型进行改进,加入融雪径流模块,经验证,模型适用于乌裕尔河流域。建立了以最高气温、最低气温、降雨和风速为变量的蒸发皿蒸发估算模型,实现了气候模型结果与水文模型的连接。利用CS IRO-M k2和CCSR/N IES两个模型模拟结果加权平均,模拟未来气候变化,探讨了水文要素对气候变化的响应。结果表明:在未来四种温室气体排放情景(SRES A 1,A 2,B 1,B 2)下,最高气温、最低气温和降水呈显著的上升趋势,而风速则呈显著下降趋势;径流深和径流系数在四种情景下都有显著上升趋势,置信水平排序为A 2>A 1>B 1>B 2;敏感性分析和趋势检验结果证明了降水是影响径流的最主要因素。     

The socio-economic impacts of climate change on water resources in South Africa

Using a computable general equilibrium approach, this study investigates the economy-wide impact of reductions in water resources in South Africa due to climate change. The simulation results show a potentially general deterioration in household welfare. Poor households are the most vulnerable. Short-run policy simulations suggest that this vulnerability can be reduced through welfare policies that maintain food consumption levels for households in the two lowest income quintiles.     

气候变化和人类活动对大凌河上游流域径流的影响

通过趋势分析方法及突变点检验方法,分析大凌河流域水文气象要素的变化趋势;结合大凌河流域人类活特征及突变点分析结果,将流域径流量序列划分为"天然基准期"和"人类活动影响期"两个阶段;应用大凌河上游水文、气象、土地利用等数据建立大凌河上游水文模型,采用弹性系数法和水文模拟法定量分析大凌河上游流域气候变化和人类活动对径流的影响。结果表明:1956—2006年,大凌河流域降水量有轻微的上升趋势,而潜在蒸发量与径流量呈现显著下降趋势,导致径流量减小的主要原因为人类活动。     

气候变化对北江流域径流影响的模拟研究

通过构建北江流域SWAT分布式水文模型,以北江流域13个雨量站10年逐月降水量及北江流域干流石角水文站同步逐月流量数据为输入条件进行水文模型参数率定,应用气候情景设置方法研究了北江流域在降水和气温等不同气候变化条件下径流量的变化规律。研究表明:气温变化1℃对年径流量及其年内分配的影响变化均在1%以内。降水量变化对年径流量影响十分显著,降水量变化10%对年径流量的影响变化可达到15%,而对径流年内分配的影响变化在1%以内,影响较小。随着气温下降和降水量的增加,枯季径流量占年内分配比例均有所上升,枯水期来水量提高,有利于流域城乡供水安全和生态用水安全。     

土地覆被和气候变化对拉萨河流域径流量的影响

以拉萨水文站上游流域为研究对象,利用分布式水文模型SWAT对拉萨河流域水文过程进行模拟,分别用1995～2000和2003～2006年两个时间段的实测数据对模型进行校准和验证。结果显示月径流模拟相关系数和模拟效率系数分别为0.88和0.84。在此基础上通过建立情景模拟,探讨拉萨河流域气候波动和土地覆被变化对径流产流量的影响。结果表明:气候变化对年径流量影响显著,在各种模拟假设情景中最多可以使径流量增加89%。土地覆被变化相对于气候变化对径流量的年际影响较弱,但对径流量的季节变化影响显著。     

气候变化影响下的赣江流域水资源变化趋势与幅度分析

利用全球气候模式输出结果,经统计降尺度模型降解后得到流域尺度的降水和气温要素,根据实测资料建立气温—蒸发回归关系以及新安江水文模型,使用耦合模拟和MK趋势分析评估未来气候变化情景下赣江流域水资源量的变化趋势和幅度。研究结果表明:未来不同排放情景下的年降水量、年蒸发量和年径流量等水文气候要素变化趋势以显著增加为主。未来年降水量、年蒸发量和年径流量的多年平均值相对基准期有较小幅度增加,最大增幅为年径流量的13.81%。降水、蒸发和径流的年内变化有明显的季节性特征,汛期径流增加、非汛期径流减少的不均匀情况加剧,在一定程度上可能增加赣江流域未来的防洪压力和枯水期供水压力。     

气候变化和人类活动对滦河下游地区水资源变化影响分析

通过对滦河下游地区气温、降水、地表水资源量、水资源总量、地下水水位等系列的变化分析,认为降水变化是造成滦河流域下游水资源年际波动性变化的主要因素,但造成流域水资源量显著下降的主要影响因素是人类活动的影响,包括以农业灌溉为主的水资源利用、土地利用活动对流域水资源的间接影响,以及向外流域持续调水等因素的直接影响。     

Modeling the impacts of climate change on the thermal and oxygen dynamics of Lake Volta

Climatic changes influence the thermal and oxygen dynamics of a lake and thus its ecological functioning. The impacts of climatic changes on tropical lakes are so far poorly studied and the extent of the effects is therefore uncertain, most investigations describing only potential effects. In this study, we applied the one-dimensional lake ecosystem model GOTM-ERGOM to quantify the effects of climate change on thermal stratification, oxygen dynamics, and primary production in meso-oligotrophic Lake Volta. GOTM-ERGOM was calibrated and validated using two years of observed data. The validated model was used to evaluate a series of future climate change scenarios. The model simulations showed good agreement with observed water temperature, dissolved oxygen and chlorophyll-a and indicated intensified stratification and reduced oxygen levels in the productive water layers of the lake. However, the longer-lasting stratification (prolonged stability) did not translate into permanent stratification. A relatively small (1?m) upward shift of thermocline depth resulted in an 8%–12% volume loss of the oxygen-rich upper mixed layer, which may be significant for the fisheries of the lake as it diminishes the size of suitable fish habitats. Light limitation of primary production renders the lake somewhat resilient to intensive algae blooms, as traceable in both the present and in the future climate scenarios. In the long term, the ongoing climate change may affect riparian communities that depend on the lake's fisheries for their livelihood. In consequence, future lake management strategies for implementation need to account for the impacts of future climate change.