Long-term precipitation trends and climate extremes in the Kelani River basin, Sri Lanka, and their impact on streamflow variability under climate change

The current patterns estimation of the water regime under climate change is one of the most urgent tasks in Ukraine and the world. Such changes are determined by fluctuations in the main climatic characteristics - precipitation and air temperature, which are defined the value of evaporation. These parameters influence on the annual runoff distribution and long-term runoff fluctuations. In particular, the annual precipitation redistribution is reflected in the corresponding changes in the river runoff. The assessment of the current state and nature of changes in precipitation and river runoff of the Siverskyi Donets River Basin was made by comparing the current period (1991-2018) with the period of the climatological normal (1961-1990). In general, for this area, it was defined the close relationship between the amount of precipitation and the annual runoff. Against the background of insignificant (about 1%) increase of annual precipitation in recent decades, it was revealed their redistribution by seasons and separate months. There is a decrease in precipitation in the cold period (November-February). This causes (along with other factors) a decrease in the amount of snow and, accordingly, the spring flood runoff. There are frequent cases of unexpressed spring floods of the Siverskyi Donets River Basin. The runoff during March-April (the period of spring flood within the Ukrainian part of the basin) decreased by almost a third. The increase of precipitation during May-June causes a corresponding (insignificant) increase in runoff in these months. The shift of the maximum monthly amount of precipitation from May (for the period 1961-1990) to June (in the current period) is observed. There is a certain threat to water supply in the region due to the shift in the minimum monthly amount of precipitation in the warm period from October to August. Compared with October, there is a higher air temperature and, accordingly, higher evaporation in August, which reduces the runoff. Such a situation is solved by rational water resources management of the basin. The possibility of replenishing water resources in the basin through the transfer runoff from the Dnieper (Dnieper-Siverskyi Donets channel) and the annual runoff redistribution in the reservoir system causes some increase in the river runoff of summer months in recent decades. This is also contributed by the activities of the river basin management structures, which control the maintenance water users' of minimum ecological flow downstream the water intakes and hydraulic structures in the rivers of the basin. Therefore, in the period of current climate change, the annual runoff distribution of the Siverskyi Donets River Basin has undergone significant changes, which is related to the annual precipitation redistribution and anthropogenic load on the basin.

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Analysis of Long-Term Trends of Annual and Seasonal Rainfall in the Awash River Basin, Ethiopia

Water ◽

10.3390/w11071498 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1498 ◽

Cited By ~ 2

Author(s):

Solomon Mulugeta ◽

Clifford Fedler ◽

Mekonen Ayana

Keyword(s):

Climate Change ◽

River Basin ◽

Summer Rainfall ◽

Seasonal Rainfall ◽

Winter Rainfall ◽

Adaptation Measures ◽

Awash River Basin ◽

Long Term Trends ◽

Increasing Trends

With climate change prevailing around the world, understanding the changes in long-term annual and seasonal rainfall at local scales is very important in planning for required adaptation measures. This is especially true for areas such as the Awash River basin where there is very high dependence on rain- fed agriculture characterized by frequent droughts and subsequent famines. The aim of the study is to analyze long-term trends of annual and seasonal rainfall in the Awash River Basin, Ethiopia. Monthly rainfall data extracted from Climatic Research Unit (CRU 4.01) dataset for 54 grid points representing the entire basin were aggregated to find the respective areal annual and seasonal rainfall time series for the entire basin and its seven sub-basins. The Mann-Kendall (MK) test and Sen Slope estimator were applied to the time series for detecting the trends and for estimating the rate of change, respectively. The Statistical software package R version 3.5.2 was used for data extraction, data analyses, and plotting. Geographic information system (GIS) package was also used for grid making, site selection, and mapping. The results showed that no significant trend (at α = 0.05) was identified in annual rainfall in all sub-basins and over the entire basin in the period (1902 to 2016). However, the results for seasonal rainfall are mixed across the study areas. The summer rainfall (June through September) showed significant decreasing trend (at α ≤ 0.1) over five of the seven sub-basins at a rate varying from 4 to 7.4 mm per decade but it showed no trend over the two sub-basins. The autumn rainfall (October through January) showed no significant trends over four of the seven sub-basins but showed increasing trends over three sub-basins at a rate varying from 2 to 5 mm per decade. The winter rainfall (February through May) showed no significant trends over four sub-basins but showed significant increasing trends (at α ≤ 0.1) over three sub-basins at a rate varying from 0.6 to 2.7 mm per decade. At the basin level, the summer rainfall showed a significant decreasing trend (at α = 0.05) while the autumn and winter rainfall showed no significant trends. In addition, shift in some amount of summer rainfall to winter and autumn season was noticed. It is evident that climate change has shown pronounced effects on the trends and patterns of seasonal rainfall. Thus, the study contribute to better understanding of climate change in the basin and the information from the study can be used in planning for adaptation measures against a changing climate.

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Potential natural vegetation dynamics driven by future long-term climate change and its hydrological impacts in the Hanjiang River basin, China

Hydrology Research ◽

10.2166/nh.2011.111 ◽

2012 ◽

Vol 43 (1-2) ◽

pp. 73-90 ◽

Cited By ~ 7

Author(s):

Fei Yuan ◽

Liliang Ren ◽

Zhongbo Yu ◽

Yonghua Zhu ◽

Jing Xu ◽

...

Keyword(s):

Climate Change ◽

River Basin ◽

21St Century ◽

Land Surface ◽

Natural Vegetation ◽

Potential Natural Vegetation ◽

Area Index ◽

Hanjiang River ◽

Ipcc Sres

Vegetation and land-surface hydrology are intrinsically linked under long-term climate change. This paper aims to evaluate the dynamics of potential natural vegetation arising from 21st century climate change and its possible impact on the water budget of the Hanjiang River basin in China. Based on predictions of the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC-SRES) A1 scenario from the PRECIS (Providing Regional Climates for Impact Studies) regional climate model, changes in plant functional types (PFTs) and leaf area index (LAI) were simulated via the Lund-Potsdam-Jena dynamic global vegetation model. Subsequently, predicted PFTs and LAIs were employed in the Xinanjiang vegetation-hydrology model for rainfall–runoff simulations. Results reveal that future long-term changes in precipitation, air temperature and atmospheric CO2 concentration would remarkably affect the spatiotemporal distribution of PFTs and LAIs. These climate-driven vegetation changes would further influence regional water balance. With the decrease in forest cover in the 21st century, plant transpiration and evaporative loss of intercepted canopy water will tend to fall while soil evaporation may rise considerably. As a result, total evapotranspiration may increase moderately with a slight increase in annual runoff depth. This indicates that, for long-term hydrological prediction, climate-induced changes in terrestrial vegetation cannot be neglected as the terrestrial biosphere plays an important role in land-surface hydrological responses.

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Economic losses from changing hydrology under future climate change, glacier shrinkage and growing water demand in the Tropical Andes

10.5194/egusphere-egu2020-12448 ◽

2020 ◽

Author(s):

Fabian Drenkhan ◽

Randy Muñoz ◽

Christian Huggel ◽

Holger Frey ◽

Fernando Valenzuela ◽

...

Keyword(s):

Climate Change ◽

River Basin ◽

Water Demand ◽

Future Climate Change ◽

Economic Losses ◽

Water Volume ◽

Tropical Andes ◽

Glacier Shrinkage ◽

Outburst Floods

In the Tropical Andes, glaciers play a fundamental role for sustaining human livelihoods and ecosystems in headwater areas and further downstream. However, current rates of glacier shrinkage driven by climate change as well as increasing water demand levels bear a threat to long-term water supply. While a growing number of research has covered impacts of climate change and glacier shrinkage on the terrestrial water cycle and potential disaster risks, the associated potential economic losses have barely been assessed.Here we present an integrated surface-groundwater assessment model for multiple water sectors under current conditions (1981-2016) and future scenarios (2050) of glacier shrinkage and growing water demand. As a case, the lumped model has been applied to the Santa river basin (including the Cordillera Blanca, Andes of Peru) within three subcatchments and considers effects from evapotranspiration, environmental flows and backflows of water use. Therefore, coupled greenhouse gas concentration (RCP2.6 and RCP8.5) and socioeconomic scenarios are used, which provide a broad range of the magnitude of glacier and water volume changes and associated economic impacts. Finally, net water volume released on the long term due to deglaciation effects is quantified and by multiple metrics converted into potential economic costs and losses for the agriculture, household and hydropower sectors. Additionally, the potential damages from outburst floods from current and future lakes have been included. Results for the entire Santa river basin show that water availability would diminish by about 11-16% (57-78 106 m&#179;) in the dry season (June-August) and by some 7-10% (103-155 106 m&#179;) during the wet season (December-February) under selected glacier shrinkage scenarios until 2050. This is a consequence of diminishing glacier contribution to streamflow which until 2050 would reduce from about 45% to 33% for June-August and from 6% to 4% for December-February. A first rough estimate suggests associated economic losses for main water demand sectors (agriculture, hydropower, drinking water) on the order of about 300 106 USD/year by 2050. Additionally, with ongoing glacier shrinkage and the formation of new lakes, about 45,000 inhabitants and 30,000 buildings are expected to be exposed to the risk of outburst floods in the 21st century.The pressure on water resources and interconnected socio-eonvironmental systems in the basin is already challenging and expected to further exacerbate within the next decades. Currently, water demand levels are considerably increasing driven by growing irrigated (export) agriculture, population and energy demand which is in a large part sustained by hydropower. A coupling of potential water scarcity driven by climate change with a lack of water governance and high human vulnerabilities, bears strong conflict potentials with negative feedbacks for socio-economic development in the Santa basin and beyond. In this context, our coupled hydro-glacial economic impact model provides important support for future decision-making and long-term water management planning. However, uncertainties are relatively high (uncertainty range to be estimated) due to a lack of (good) hydro-climatic and socio-economic information at appropriate spatiotemporal scales. The presented model framework is potentially transferable to other high mountain catchments in the Tropical Andean region and beyond.

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Can on-farm irrigation reservoirs enhance long-term sustainability of large irrigated systems? The case of Riegos del Alto Aragón (Spain)

10.5194/egusphere-egu2020-10397 ◽

2020 ◽

Author(s):

David Haro-Monteagudo ◽

Leticia Palazón ◽

Santiago Beguería

Keyword(s):

Climate Change ◽

Decision Making ◽

River Basin ◽

Irrigation District ◽

Allocation Model ◽

Ebro River ◽

Irrigated Area ◽

Environmental Objectives ◽

On Farm

With a total irrigated area above 127,000 ha divided into 58 sectors, the Riegos del Alto Arag&#243;n (RAA) irrigation district is currently the largest irrigated area in Spain and in the European Union. Also, it is the largest water user within the Gallego-Cinca subsystem within the Ebro River Basin, which also supplies water to 588 livestock operations, 10 industrial polygons, and 110 populated areas. Although there are plans to increase the irrigated area by another additional 47,000 ha, the system is currently close to its resource limit and several supply restrictions took place in the last years with consequent impacts on agricultural productivity. Moreover, this expansion of the irrigated area collides with environmental objectives in the region, mostly due to water quality and nature conservancy aspects, as well as with other water uses downstream.The forecasted effects of climate change on future water resources produced in the Pyrenees (the major source of water in the system), as well as market prices, national and international trade and agricultural policies, among other variables, are surrounded by a high level of uncertainty that difficult investment decision-making. Some of the adaptation measures initially devised for the system, e.g. construction of new large reservoirs in the Gallego and Cinca rivers, require either confronting further environmental conflicts or large energy expenses, when not both. With the end of the era of large public works, there is a need to identify new and robust strategies for climate change adaptation. One of these strategies is the construction of private on-farm reservoirs within the RAA system that started in recent years.The present work evaluates the contribution of on-farm reservoirs to enhancing the long-term sustainability of the RAA system using a multi-model and multi-scenario approach. The Soil and Water Assessment Tool (SWAT) was used to simulate water provisions from the Gallego-Cinca headwater system under an ensemble of downscaled climate models. Afterward, SWAT outputs were fed into a water allocation model built with AQUATOOL to simulate the management of the system's reservoirs, including on-farm reservoirs, and the water supply to the different demands. The performance of agricultural demands and compliance with environmental flow requirements in the system was evaluated for different on-farm reservoir sizes and combined with construction and operational costs to develop sustainability/investment curves. The outcomes have the potential to better inform decision-making from farmers in RAA as well as from managers in the Ebro River Basin Agency, providing further understanding of the system's dynamics under climatic change.

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Soil loss estimation using rusle model to prioritize erosion control in KELANI river basin in Sri Lanka

International Soil and Water Conservation Research ◽

10.1016/j.iswcr.2019.01.003 ◽

2019 ◽

Vol 7 (2) ◽

pp. 130-137 ◽

Cited By ~ 17

Author(s):

Cassim Mohamed Fayas ◽

Nimal Shantha Abeysingha ◽

Korotta Gamage Shyamala Nirmanee ◽

Dinithi Samaratunga ◽

Ananda Mallawatantri

Keyword(s):

Sri Lanka ◽

River Basin ◽

Soil Loss ◽

Erosion Control ◽

Loss Estimation ◽

Rusle Model ◽

Kelani River

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Long-Term Variability in Potential Evapotranspiration, Water Availability and Drought under Climate Change Scenarios in the Awash River Basin, Ethiopia

Atmosphere ◽

10.3390/atmos11090883 ◽

2020 ◽

Vol 11 (9) ◽

pp. 883 ◽

Cited By ~ 1

Author(s):

Mahtsente Tadese ◽

Lalit Kumar ◽

Richard Koech

Keyword(s):

Climate Change ◽

River Basin ◽

Water Availability ◽

Potential Evapotranspiration ◽

Management Strategies ◽

Water Shortage ◽

Climate Change Scenarios ◽

Awash River Basin ◽

Mitigate Climate Change

Understanding the hydrological processes of a watershed in response to climate change is vital to the establishment of sustainable environmental management strategies. This study aimed to evaluate the variability of potential evapotranspiration (PET) and water availability in the Awash River Basin (ARB) under different climate change scenarios and to relate these with long-term drought occurrences in the area. The PET and water availability of the ARB was estimated during the period of 1995–2009 and two future scenarios (2050s and 2070s). The representative concentration pathways (RCP4.5 and RCP8.5) simulations showed an increase in the monthly mean PET from March to August in the 2050s, and all the months in the 2070s. The study also identified a shortage of net water availability in the majority of the months investigated and the occurrence of mild to extreme drought in about 40–50% of the analysed years at the three study locations (Holetta, Koka Dam, and Metehara). The decrease in water availability and an increase in PET, combined with population growth, will aggravate the drought occurrence and food insecurity in the ARB. Therefore, integrated watershed management systems and rehabilitation of forests, as well as water bodies, should be addressed in the ARB to mitigate climate change and water shortage in the area.

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