scholarly journals Climatic controls on watershed reference evapotranspiration vary dramatically during the past 50 years in southern China

Author(s):  
Mengsheng Qin ◽  
Lu Hao ◽  
Lei Sun ◽  
Yongqiang Liu ◽  
Ge Sun

Abstract. Reference evapotranspiration (ETo) is an important hydrometeorological term widely used in water resource management, hydrological modeling, and understanding and projecting the hydrological effects of future climate change and land use change. Identifying the individual climatic controls on ETo helps better understand the processes of global climatic change impacts on local water resources and also simplify modeling efforts to predict actual evapotranspiration. We conducted a case study on the Qinhuai River Basin (QRB), a watershed dominated by a humid subtropical climate and mixed land uses in southern China. Long term (1961–2012) daily meteorological data at six weather stations across the watershed were used to estimate ETo by the FAO-56 Penman−Monteith model. The seasonal and annual trends of ETo were examined using the Mann−Kendall nonparametric test. The individual contributions from each meteorological variable were quantified by a detrending method. The results showed that basin-wide annual ETo had a decreasing trend during 1961–1987 due to decreased wind speed (WS), solar radiation (Rs), vapor pressure deficit (VPD), and increased relative humidity (RH). These variables had different magnitudes of contribution to the ETo trend in different seasons examined during 1961−1987. However, during 1988–2012, both seasonal and annual ETo showed an increasing trend, mainly due to increased VPD and decreased RH and, to lesser extent, to decreased absolute humidity (AH) and a rising air temperature. We show that the key climatic controls on ETo have dramatically shifted as a result of global climate change during the past five decades. Now the atmospheric demand, instead of air temperature alone, is a major control on ETo. Thus, we conclude that accurately predicting current and future ETo and hydrological change under a changing climate must consider changes in VPD (i.e., air humidity and temperature) in the study region. Water resource management in the study basin must consider the increasing trend of ETo to meet the associated increasing water demand for irrigation agriculture and domestic water uses.

Author(s):  
R. T. Montes-Rojas ◽  
J. E. Ospina-Noreña ◽  
C. Gay-García ◽  
C. Rueda-Abad ◽  
I. Navarro-González

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2642 ◽  
Author(s):  
Thuc D. Phan ◽  
James C. R. Smart ◽  
Ben Stewart-Koster ◽  
Oz. Sahin ◽  
Wade L. Hadwen ◽  
...  

Bayesian networks (BNs) are widely implemented as graphical decision support tools which use probability inferences to generate “what if?” and “which is best?” analyses of potential management options for water resource management, under climate change and socio-economic stressors. This paper presents a systematic quantitative literature review of applications of BNs for decision support in water resource management. The review quantifies to what extent different types of data (quantitative and/or qualitative) are used, to what extent optimization-based and/or scenario-based approaches are adopted for decision support, and to what extent different categories of adaptation measures are evaluated. Most reviewed publications applied scenario-based approaches (68%) to evaluate the performance of management measures, whilst relatively few studies (18%) applied optimization-based approaches to optimize management measures. Institutional and social measures (62%) were mostly applied to the management of water-related concerns, followed by technological and engineered measures (47%), and ecosystem-based measures (37%). There was no significant difference in the use of quantitative and/or qualitative data across different decision support approaches (p = 0.54), or in the evaluation of different categories of management measures (p = 0.25). However, there was significant dependence (p = 0.076) between the types of management measure(s) evaluated, and the decision support approaches used for that evaluation. The potential and limitations of BN applications as decision support systems are discussed along with solutions and recommendations, thereby further facilitating the application of this promising decision support tool for future research priorities and challenges surrounding uncertain and complex water resource systems driven by multiple interactions amongst climatic and non-climatic changes.


Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1062 ◽  
Author(s):  
Sleemin Lee ◽  
Doosun Kang

The increasing frequency of extreme droughts and flash floods in recent years due to climate change has increased the interest in sustainable water use and efficient water resource management. Because the water resource sector is closely related to human activities and affected by interactions between the humanities and social sciences, there is a need for interdisciplinary research that can consider various elements, such as society and the economy. This study elucidates relationships within the social and hydrological systems and quantitatively analyzes the effects of a multi-purpose dam on the target society using a system dynamics model. A causal loop was used to identify causal relationships between the social and hydrological components of the target area, and a simulation model was constructed using the system dynamics technique. Additionally, climate change and socio-economic scenarios were applied to analyze the future effects of the multi-purpose dam on population change, the regional economy, water use, and flood damage prevention in the target area. The model proved reliable in predicting socio-economic changes in the target area and can be used to make decisions about efficient water resource management and water-resource-related facility planning.


2019 ◽  
Vol 30 (3) ◽  
pp. 11-21 ◽  
Author(s):  
Steven Matome Mathetsa ◽  
Mulala Danny Simatele ◽  
Isaac T. Rampedi ◽  
Gerhard Gericke

It is increasingly acknowledged that the water-energy-climate change (WECC) nexus is one of the synergies that pose a significant risk to achievement of sustainable development goals (SDGs), specifically numbers six, seven and thirteen. There are suggestions that climate change outcomes such as increased temperature and drought episodes have implications for water availability, which in turn affects energy production in countries dependent on hydropower, pump-storage or coal-generated electricity, including South Africa. This development therefore calls for improved understanding of how to effectively manage the challenges that arise from this nexus, to mitigate the impacts it may have on achieving the associated SDGs. This study, which is based on an in-depth appraisal of existing developments, assessed the potential of the integrated water resource management framework in understanding the WECC nexus and its implications for South Africa’s sustainable development endeavours, particularly in the context of water resource management and utilisation. The study revealed South Africa’s lack of integrated, effective, and efficient institutions and policy framework to comprehensively manage the challenges emanating from this nexus. It identified an urgent need to develop systems and processes through which South Africa can handle the challenges as well as capture the benefits that may be obtained from this nexus.


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