Data Construction and Spatiotemporal Trend Attribution of Runoff over the African Continent (1981–2016)

2021 ◽  
Author(s):  
Fidele Karamage ◽  
Yongwei Liu ◽  
Yuanbo Liu
Keyword(s):  
Climate Change ◽  
Statistical Methods ◽  
Human Activities ◽  
Water Resource Management ◽  
Agricultural Land ◽  
Curve Number ◽  
Discharge Data ◽  
Resource Managers ◽  
Runoff Change ◽  
Natural Resource Managers

AbstractThe availability of streamflow records in Africa has been declining since the 1980s due to malfunctioning gauging stations and data collection failures. Africa also has insufficient hydrological information owing to the allocation of few resources to research efforts. Unreliable runoff datasets and large uncertainties in runoff trends due to climate change patterns and human activities are major challenges to water resource management in Africa. Therefore, this study aimed to improve runoff estimates and to assess runoff trend responses to climate change and human activities in Africa during 1981–2016. Using statistical methods, monthly gridded runoff datasets were generated for the period of 1981–2016 from a modified runoff curve number method calibrated with river discharge data from 535 gauging stations. According to the cross-validation results, the constructed runoff datasets comprised the Nash and Sutcliffe coefficients ranging from 0.5 to 1, coefficients of determination ranging from 0.5 to 1 and percent biases between ±25% for a large number of stations up to 73%, 80% and 91% of the 535 gauged catchments used as references. Analysis of runoff trend responses to climate change and human activities revealed that land cover change contributed more (72%) to the observed net runoff change (0.30%•a−1) than continental climate changes (28%). These contributions were results of cropland expansion rate of 0.46%•a−1 and a precipitation increase of 0.07%•a−1. The performance and simplicity of the statistical methods used in this study could be useful for improving runoff estimations in other regions with limited streamflow data data. The results of the current study could be important to natural resource managers and decision makers in terms of raising awareness of climate change adaptation strategies and agricultural land-use policies in Africa.

scholarly journals Response of LUCC on Runoff Generation Process in Middle Yellow River Basin: The Gushanchuan Basin

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1237 ◽  
Author(s):  
Caihong Hu ◽  
Li Zhang ◽  
Qiang Wu ◽  
Shan-e-hyder Soomro ◽  
Shengqi Jian
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Yellow River ◽  
Trend Test ◽  
Generation Process ◽  
Runoff Generation ◽  
Contribution Rate ◽  
Runoff Reduction ◽  
Runoff Change ◽  
Significant Downward Trend

Runoff reduction in most river basins in China has become a hotpot in recent years. The Gushanchuan river, a primary tributary of the middle Yellow river, Northern China, showed a significant downward trend in the last century. Little is known regarding the relative contributions of changing environment to the observed hydrological trends and response on the runoff generation process in its watershed. On the basis of observed hydrological and meteorological data from 1965–2010, the Mann-Kendall trend test and climate elasticity method were used to distinguish the effects of climate change and human activities on runoff in the Gushanchuan basin. The results indicate that the runoff in the Gushanchuan Basin has experienced significant declines as large as 77% from 1965 to 2010, and a mutation point occurred around 1997; the contribution rate of climate change to runoff change is 12.9–15.1%, and the contribution rate of human activities to runoff change is 84.9–87.1%. Then we divided long-term data sequence into two stages around the mutation point, and analyzed runoff generation mechanisms based on land use and cover changes (LUCC). We found that the floods in the Gushanchuan Basin were still dominated by Excess-infiltration runoff, but the proportion in 1965–1997 and 1998–2010 decreased gradually (68.46% and 45.83% in turn). The proportion of Excess-storage runoff and Mixed runoff has increased, which means that the runoff is made up of more runoff components. The variation law of the LUCC indicates that the forest area increased by 49.61%, the confluence time increased by 50.42%, and the water storage capacity of the watershed increased by 30.35%.

scholarly journals Impacts of climate change and human activities on runoff change in a typical arid watershed, NW China

2021 ◽  
Vol 121 ◽  
pp. 107013
Author(s):  
Dongxiang Xue ◽  
Junju Zhou ◽  
Xi Zhao ◽  
Chunfang Liu ◽  
Wei Wei ◽  
...  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Nw China ◽  
Runoff Change ◽  
Impacts Of Climate Change

Assessing the Impacts of Climate Change and Land Use/Cover Change on Runoff Based on Multiple Water-Energy Balance Models

2020 ◽  
Author(s):  
Manling Xiong
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Energy Balance ◽  
Water Resource Management ◽  
Potential Evapotranspiration ◽  
Heihe River ◽  
Runoff Variation ◽  
Runoff Change ◽  
Energy Balance Models ◽  
Impacts Of Climate Change

<p>The runoff in river systems has been significantly changed by climate change and land use/cover change (LUCC), while the magnitude and patterns vary because of the factors. Investigating the major factor impacting runoff variation is necessary for water resource management. In this work, five different water-energy balance models are used to analyze the cause of runoff variations; of these models, three are based on the Budyko framework and two are based on the ecohydrological conceptual framework. The approach is demonstrated using the upper-midstream of the Heihe Rivers. The results suggest LUCC is the dominant cause of runoff change in the range of 59.92% ~ 65.14%. The estimated impacts of climate change and LUCC are consistent among the five models. Cropping is the major human activity resulting in LUCC at the upper-midstream of the Heihe River. Meanwhile, the change in runoff is more sensitive to precipitation than to potential evapotranspiration. Our work summarizes five widely used water-energy balance models used to explain the impacts of climate change and LUCC on runoff, which may be of importance in explaining the mechanism of runoff change.</p>

scholarly journals Climate Change Vulnerability Assessment of Imperiled Plants in the Mojave Desert

2021 ◽  
Author(s):  
Jennifer Wilkening ◽  
Lara Kobelt ◽  
Tiffany J. Pereira
Keyword(s):  
Climate Change ◽  
Plant Species ◽  
Vulnerability Assessment ◽  
Mojave Desert ◽  
Climatic Conditions ◽  
Contributing Factors ◽  
Climate Change Vulnerability ◽  
Resource Managers ◽  
Climate Change Vulnerability Assessment ◽  
Natural Resource Managers

The Mojave Desert in the southwestern United States is one of the hottest and driest areas of North America. Climate change is likely to exacerbate these conditions. The region is home to many endemic plant species, including 24 federally threatened species. The impact of climate change factors on these sensitive Mojave Desert species is relatively unknown. Here we used a climate change vulnerability assessment to determine which imperiled plants may be most affected by changing climatic conditions. We evaluated the vulnerability of each species under future climate scenarios and calculated scores using metrics such as exposure, sensitivity, niche breadth, and dispersal capability. We found that most listed plant species were vulnerable to climate change, with 21% (N = 5) classified as extremely vulnerable, 25% (N = 6) classified as highly vulnerable, and 42% (N = 10) classified as moderately vulnerable. Contributing factors most frequently associated with vulnerability included various barriers to migration, high habitat specificity, and species sensitivity to changes in hydrological patterns. Many of these species are already threatened by ongoing anthropogenic stressors such as urban growth and associated developments, and these results suggest that climate change will pose additional challenges for conservation and management. Natural resource managers can use the vulnerability ranking and contributing factors identified from these analyses to inform ecological decisions related to threatened plants throughout desert regions.

scholarly journals Effects of Climate Change and Human Activities on Surface Runoff in the Luan River Basin

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Sidong Zeng ◽  
Chesheng Zhan ◽  
Fubao Sun ◽  
Hong Du ◽  
Feiyu Wang
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Human Activities ◽  
Surface Runoff ◽  
Hydrological Modeling ◽  
Assessment Tool ◽  
Integrated Method ◽  
Climate Elasticity ◽  
Runoff Change ◽  
Runoff Changes

Quantifying the effects of climate change and human activities on runoff changes is the focus of climate change and hydrological research. This paper presents an integrated method employing the Budyko-based Fu model, hydrological modeling, and climate elasticity approaches to separate the effects of the two driving factors on surface runoff in the Luan River basin, China. The Budyko-based Fu model and the double mass curve method are used to analyze runoff changes during the period 1958~2009. Then two types of hydrological models (the distributed Soil and Water Assessment Tool model and the lumped SIMHYD model) and seven climate elasticity methods (including a nonparametric method and six Budyko-based methods) are applied to estimate the contributions of climate change and human activities to runoff change. The results show that all quantification methods are effective, and the results obtained by the nine methods are generally consistent. During the study period, the effects of climate change on runoff change accounted for 28.3~46.8% while those of human activities contributed with 53.2~71.7%, indicating that both factors have significant effects on the runoff decline in the basin, and that the effects of human activities are relatively stronger than those of climate change.

scholarly journals Quantifying the Impacts of Climate Change and Human Activities on Runoff in the Lancang River Basin Based on the Budyko Hypothesis

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3501
Author(s):  
Hao Liu ◽  
Zheng Wang ◽  
Guangxing Ji ◽  
Yanlin Yue
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Human Activities ◽  
Mean Annual Precipitation ◽  
Hydrological Process ◽  
Lancang River ◽  
Runoff Change ◽  
Runoff Series ◽  
The Lancang River Basin ◽  
The Impact

Based on the Lancang River Basin (LRB) hydro–meteorological data from 1961 to 2015, this study uses the Mann–Kendall trend test and mutation test to analyze the trend of hydro–meteorological variables, as well as which year the runoff series changes, respectively. We applied the Choudhury–Yang equation to calculate the climate and catchment landscape elasticity of runoff. Then we quantified the impact of climate change and human activities on runoff change. The results show that: (1) the mean annual precipitation (P) in LRB showed an insignificant decline, the annual potential evapotranspiration (E0) showed a significant increase, and the runoff depth (R) showed a significant decrease; (2) the abrupt change of the R occurred in 2005. Both the climate and catchment landscape elasticity of runoff increased, which means that the hydrological process of LRB became more sensitive to climate changes and human activities; (3) compared with the base period (1961–2004), the reduction of P was the leading cause of runoff reduction, with a contribution of 45.64%. The contribution of E0 and human activities to runoff changes are 13.91% and 40.45%, respectively.

scholarly journals Using Budyko-Type Equations for Separating the Impacts of Climate and Vegetation Change on Runoff in the Source Area of the Yellow River

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3418
Author(s):  
Dan Yan ◽  
Zhizhu Lai ◽  
Guangxing Ji
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Vegetation Change ◽  
Yellow River ◽  
Climatic Factors ◽  
Source Area ◽  
The Yellow River ◽  
Vegetation Changes ◽  
Potential Evaporation ◽  
Runoff Change

Assessing the contribution rates of climate change and human activities to the runoff change in the source area of the Yellow River can provide support for water management in the Yellow River Basin. This paper firstly uses a multiple linear regression method to evaluate the contribution rates of climate change and human activities to the vegetation change in the source area of the Yellow River. Next, the paper uses the Budyko hypothesis method to calculate the contribution rates of climatic factors (including precipitation, potential evaporation, and subsequent vegetation changes) and vegetation changes caused by human activities to the runoff change of the Tangnaihai Hydrometric Station. The results showed that: (1) the annual runoff and precipitation in the source area of the Yellow River have a downward trend, while the annual potential evaporation and NDVI (Normalized Difference Vegetation Index) show an increasing trend; (2) The contribution rates of climate change and human activities to the vegetation change in the source area of the Yellow River is 62.79% and 37.21%, respectively; (3) The runoff change became more and more sensitive to changes in climate and underlying surface characteristic parameters; (4) The contribution rates of climatic factors (including precipitation, potential evaporation, and subsequent vegetation changes) and vegetation changes caused by human activities to the runoff change at Tangnaihai Hydrological Station are 75.33% and 24.67%, respectively; (5) The impact of precipitation on runoff reduction is more substantial than that of potential evaporation.

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