Understanding the Impacts of Climate Change in the Tana River Basin, Kenya

Abstract. In the Tana River Basin in Kenya, six Regional Circulation Models (RCMs) simulating two Representative Concentration Pathways (RCPs) (i.e., 4.5 and 8.5) were used as input to the Soil and Water Assessment Tool (SWAT) model to determine the possible implications for the hydrology and water resources of the basin. Four hydrological characteristics – water yield, groundwater recharge, base flow and flow regulation – were determined and mapped throughout the basin for three 30-year time periods: 2020–2049, 2040–2069 and 2070–2099. Results were compared with a baseline period, 1983–2011. All four hydrological characteristics show steady increases under both RCPs for the entire basin but with considerable spatial heterogeneity and greater increases under RCP 8.5 than RCP 4.5. The results have important implications for the way water resources in the basin are managed. It is imperative that water managers and policy makers take into account the additional challenges imposed by climate change in operating built infrastructure.

Download Full-text

Modeling hydrologic processes and potential responses to climate change in an agro-silvo-pastoral watershed in the Mediterranean area

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-383-151-2020 ◽

2020 ◽

Vol 383 ◽

pp. 151-158

Author(s):

Youssef Brouziyne ◽

Lahcen Benaabidate ◽

Aziz Abouabdillah ◽

Rachid Bouabid ◽

Abdelghani Chehbouni

Keyword(s):

Climate Change ◽

Water Resources ◽

Water Balance ◽

Assessment Tool ◽

Flow Direction ◽

Swat Model ◽

Water Yield ◽

Climate Change Scenarios ◽

Climate Conditions ◽

Hydrologic Processes

Abstract. Precipitation changes and water use patterns are two factors affecting the water quantity; obviously, hydrologic processes are always linked to many elements in the watershed scale, so to understand water management issues it is fundamental to analyze the different elements of hydrologic processes occurring in the watershed. In this study, the “SWAT” model (Soil and Water Assessment Tool) has been used to simulate the water balance for the present climate conditions on a semi arid watershed located in the central North of Morocco (R'dom). The study watershed covers an area of 1993 km2, and is hosting farming, pasture and forestry related activities. The water stress situation in the R'dom watershed can be summarized as limited resource facing increasing water demand. SWAT model was first run and calibrated under current climate; and was driven with downscaled climate simulations to generate future hydrological projections for R'dom watershed in the 2031 to 2050 horizon under two Representative Concentration Pathways (RCPs): 4.5 and 8.5. The results of the study showed that the water balance in R'dom watershed is dominated by evapotranspiration and the water resources distribution within the watershed is uneven and follows a decreasing gradient matching the flow direction. The main results of climate change scenarios showed that R'dom watershed will undergo significant decrease of water resources availability with more economic impact under the scenario RCP8.5 as all areas hosting the economical activities will be affected and the highest changes of water yield should be under this scenario.

Download Full-text

Climate change variability assessment on water resources by SWAT model: A Review

WEENTECH Proceedings in Energy ◽

10.32438/wpe.23021 ◽

2021 ◽

pp. 246-268

Author(s):

Amit Raj ◽

M.Siva Kumar ◽

Satish Kumar ◽

H.P. Singh

Keyword(s):

Climate Change ◽

Water Resources ◽

21St Century ◽

Assessment Tool ◽

Swat Model ◽

Climate Change Impacts ◽

Renewable Resource ◽

Base Flow ◽

Weather Data ◽

Geographical Regions

Water is a renewable resource for the Sustaining Ecosystem. Rapid industrialization and population impacts the climate. The imbalance of Climate changes over various geographical regions affects the hydrological and morphological behaviour of water resources. The Water balances of the system are analysed via the SWAT Model (Soil and Water Assessment Tool). By simulating and predicting future hydrological behaviour with different scenarios using many climatological models. Using weather data and predicting future hydrological outputs such as Runoff, Temperature, Base flow, groundwater flow, AET etc. in 21st century. Model is calibrated and validated using statistical methods. Results of various modelling Researches in field of SWAT and their major findings are discussed in this review paper. The future Scope of SWAT modelling and its Applications are also recommended. Forty papers are discussed in tabular form with their results and their future improvements were concluded. This paper fulfills a need for precise and quick reviews of recent researches in field of SWAT modelling with climate change on water resources. This will help researchers, academician’s insights into precise climate change impacts on water resources in 21st Century. Necessary steps to be adopted for their successful extreme repercussions of climate change and measures adopted for managing the severe damages to our Ecosystem with sustainable development goals in new millennium are discussed.

Download Full-text

Land cover and climate change effects on streamflow and sediment yield: a case study of Tapacurá River basin, Brazil

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-371-189-2015 ◽

2015 ◽

Vol 371 ◽

pp. 189-193 ◽

Cited By ~ 1

Author(s):

J. Y. G. Santos ◽

R. M. Silva ◽

J. G. Carvalho Neto ◽

S. M. G. L. Montenegro ◽

C. A. G. Santos ◽

...

Keyword(s):

Climate Change ◽

Land Cover ◽

River Basin ◽

Sediment Yield ◽

Assessment Tool ◽

Swat Model ◽

Base Flow ◽

Climate Change Effects ◽

Monthly Streamflow ◽

The Impact

Abstract. This study assesses the impact of the land use and climate changes between 1967–2008 on the streamflow and sediment yield in Tapacurá River basin (Brazil) using the Soil and Water Assessment Tool (SWAT) model. The model was calibrated and validated by comparing simulated mean monthly streamflow with observed long-term mean monthly streamflow. The obtained R2 and Nash–Sutcliffe efficiency values to streamflow data were respectively 0.82 and 0.71 for 1967–1974, and 0.84 and 0.82 for 1995–2008. The results show that the land cover and climate change affected the basin hydrology, decreasing the streamflow and sediment yield (227.39 mm and 18.21 t ha−1 yr−1 for 1967–1974 and 182.86 mm and 7.67 t ha−1 yr−1 for 1995–2008). The process changes are arising mainly due to the land cover/use variability, but, mainly due to the decreasing in the rainfall rates during 1995–2008 when compared with the first period analysed, which in turn decreased the streamflow and sediments during the wet seasons and reduced the base flow during the dry seasons.

Download Full-text

Application of SWAT in Hydrological Simulation of Complex Mountainous River Basin (Part II: Climate Change Impact Assessment)

Water ◽

10.3390/w13111548 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1548

Author(s):

Suresh Marahatta ◽

Deepak Aryal ◽

Laxmi Prasad Devkota ◽

Utsav Bhattarai ◽

Dibesh Shrestha

Keyword(s):

Climate Change ◽

River Basin ◽

Climate Models ◽

Assessment Tool ◽

Swat Model ◽

Global Climate Models ◽

Climate Data ◽

The Future ◽

The Impact ◽

Mountainous River

This study aims at analysing the impact of climate change (CC) on the river hydrology of a complex mountainous river basin—the Budhigandaki River Basin (BRB)—using the Soil and Water Assessment Tool (SWAT) hydrological model that was calibrated and validated in Part I of this research. A relatively new approach of selecting global climate models (GCMs) for each of the two selected RCPs, 4.5 (stabilization scenario) and 8.5 (high emission scenario), representing four extreme cases (warm-wet, cold-wet, warm-dry, and cold-dry conditions), was applied. Future climate data was bias corrected using a quantile mapping method. The bias-corrected GCM data were forced into the SWAT model one at a time to simulate the future flows of BRB for three 30-year time windows: Immediate Future (2021–2050), Mid Future (2046–2075), and Far Future (2070–2099). The projected flows were compared with the corresponding monthly, seasonal, annual, and fractional differences of extreme flows of the simulated baseline period (1983–2012). The results showed that future long-term average annual flows are expected to increase in all climatic conditions for both RCPs compared to the baseline. The range of predicted changes in future monthly, seasonal, and annual flows shows high uncertainty. The comparative frequency analysis of the annual one-day-maximum and -minimum flows shows increased high flows and decreased low flows in the future. These results imply the necessity for design modifications in hydraulic structures as well as the preference of storage over run-of-river water resources development projects in the study basin from the perspective of climate resilience.

Download Full-text

A Review of SWAT Model Application in Africa

Water ◽

10.3390/w13091313 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1313

Author(s):

George Akoko ◽

Tu Hoang Le ◽

Takashi Gomi ◽

Tasuku Kato

Keyword(s):

Climate Change ◽

Land Use ◽

Water Resources ◽

Hydrological Modeling ◽

Assessment Tool ◽

Swat Model ◽

Data Availability ◽

Mitigation Measures ◽

Model Parameterization ◽

Basin Scale

The soil and water assessment tool (SWAT) is a well-known hydrological modeling tool that has been applied in various hydrologic and environmental simulations. A total of 206 studies over a 15-year period (2005–2019) were identified from various peer-reviewed scientific journals listed on the SWAT website database, which is supported by the Centre for Agricultural and Rural Development (CARD). These studies were categorized into five areas, namely applications considering: water resources and streamflow, erosion and sedimentation, land-use management and agricultural-related contexts, climate-change contexts, and model parameterization and dataset inputs. Water resources studies were applied to understand hydrological processes and responses in various river basins. Land-use and agriculture-related context studies mainly analyzed impacts and mitigation measures on the environment and provided insights into better environmental management. Erosion and sedimentation studies using the SWAT model were done to quantify sediment yield and evaluate soil conservation measures. Climate-change context studies mainly demonstrated streamflow sensitivity to weather changes. The model parameterization studies highlighted parameter selection in streamflow analysis, model improvements, and basin scale calibrations. Dataset inputs mainly compared simulations with rain-gauge and global rainfall data sources. The challenges and advantages of the SWAT model’s applications, which range from data availability and prediction uncertainties to the model’s capability in various applications, are highlighted. Discussions on considerations for future simulations such as data sharing, and potential for better future analysis are also highlighted. Increased efforts in local data availability and a multidimensional approach in future simulations are recommended.

Download Full-text

Hydrological Alteration Index as an Indicator of the Calibration Complexity of Water Quantity and Quality Modeling in the Context of Global Change

Water ◽

10.3390/w12010115 ◽

2019 ◽

Vol 12 (1) ◽

pp. 115 ◽

Cited By ~ 3

Author(s):

Roxelane Cakir ◽

Mélanie Raimonet ◽

Sabine Sauvage ◽

Javier Paredes-Arquiola ◽

Youen Grusson ◽

...

Keyword(s):

Climate Change ◽

Water Quality ◽

Water Resources ◽

Stream Water ◽

Swat Model ◽

Water Yield ◽

Observation Data ◽

Hydrological Alteration ◽

Water Quality And Quantity ◽

The Impact

Modeling is a useful way to understand human and climate change impacts on the water resources of agricultural watersheds. Calibration and validation methodologies are crucial in forecasting assessments. This study explores the best calibration methodology depending on the level of hydrological alteration due to human-derived stressors. The Soil and Water Assessment Tool (SWAT) model is used to evaluate hydrology in South-West Europe in a context of intensive agriculture and water scarcity. The Index of Hydrological Alteration (IHA) is calculated using discharge observation data. A comparison of two SWAT calibration methodologies are done; a conventional calibration (CC) based on recorded in-stream water quality and quantity and an additional calibration (AC) adding crop managements practices. Even if the water quality and quantity trends are similar between CC and AC, water balance, irrigation and crop yields are different. In the context of rainfall decrease, water yield decreases in both CC and AC, while crop productions present opposite trends (+33% in CC and −31% in AC). Hydrological performance between CC and AC is correlated to IHA: When the level of IHA is under 80%, AC methodology is necessary. The combination of both calibrations appears essential to better constrain the model and to forecast the impact of climate change or anthropogenic influences on water resources.

Download Full-text

Simulating the Impact of Climate Change on the Hydrological Regimes of a Sparsely Gauged Mountainous Basin, Northern Pakistan

Water ◽

10.3390/w11102141 ◽

2019 ◽

Vol 11 (10) ◽

pp. 2141 ◽

Cited By ~ 4

Author(s):

Saddique ◽

Usman ◽

Bernhofer

Keyword(s):

Climate Change ◽

River Basin ◽

Assessment Tool ◽

High Elevation ◽

Climate Simulation ◽

Water Yield ◽

Research Station ◽

Impact Of Climate Change ◽

Global Circulation Models ◽

The Impact

Projected climate changes for the 21st century may cause great uncertainties on the hydrology of a river basin. This study explored the impacts of climate change on the water balance and hydrological regime of the Jhelum River Basin using the Soil and Water Assessment Tool (SWAT). Two downscaling methods (SDSM, Statistical Downscaling Model and LARS-WG, Long Ashton Research Station Weather Generator), three Global Circulation Models (GCMs), and two representative concentration pathways (RCP4.5 and RCP8.5) for three future periods (2030s, 2050s, and 2090s) were used to assess the climate change impacts on flow regimes. The results exhibited that both downscaling methods suggested an increase in annual streamflow over the river basin. There is generally an increasing trend of winter and autumn discharge, whereas it is complicated for summer and spring to conclude if the trend is increasing or decreasing depending on the downscaling methods. Therefore, the uncertainty associated with the downscaling of climate simulation needs to consider, for the best estimate, the impact of climate change, with its uncertainty, on a particular basin. The study also resulted that water yield and evapotranspiration in the eastern part of the basin (sub-basins at high elevation) would be most affected by climate change. The outcomes of this study would be useful for providing guidance in water management and planning for the river basin under climate change.

Download Full-text

Predicting hydrologic responses to climate changes in highly glacierized and mountainous region Upper Indus Basin

Royal Society Open Science ◽

10.1098/rsos.191957 ◽

2020 ◽

Vol 7 (8) ◽

pp. 191957 ◽

Cited By ~ 2

Author(s):

Muhammad Izhar Shah ◽

Asif Khan ◽

Tahir Ali Akbar ◽

Quazi K. Hassan ◽

Asim Jahangir Khan ◽

...

Keyword(s):

Climate Change ◽

Water Resources ◽

Climate Model ◽

Assessment Tool ◽

Model Simulation ◽

Global Climate ◽

Meteorological Data ◽

Swat Model ◽

Indus Basin ◽

Upper Indus Basin

The Upper Indus Basin (UIB) is a major source of supplying water to different areas because of snow and glaciers melt and is also enduring the regional impacts of global climate change. The expected changes in temperature, precipitation and snowmelt could be reasons for further escalation of the problem. Therefore, estimation of hydrological processes is critical for UIB. The objectives of this paper were to estimate the impacts of climate change on water resources and future projection for surface water under different climatic scenarios using soil and water assessment tool (SWAT). The methodology includes: (i) development of SWAT model using land cover, soil and meteorological data; (ii) calibration of the model using daily flow data from 1978 to 1993; (iii) model validation for the time 1994–2003; (iv) bias correction of regional climate model (RCM), and (v) utilization of bias-corrected RCM for future assessment under representative concentration pathways RCP4.5 and RCP8.5 for mid (2041–2070) and late century (2071–2100). The results of the study revealed a strong correlation between simulated and observed flow with R 2 and Nash–Sutcliff efficiency (NSE) equal to 0.85 each for daily flow. For validation, R 2 and NSE were found to be 0.84 and 0.80, respectively. Compared to baseline period (1976–2005), the result of RCM showed an increase in temperature ranging from 2.36°C to 3.50°C and 2.92°C to 5.23°C for RCP4.5 and RCP8.5 respectively, till the end of the twenty-first century. Likewise, the increase in annual average precipitation is 2.4% to 2.5% and 6.0% to 4.6% (mid to late century) under RCP4.5 and RCP8.5, respectively. The model simulation results for RCP4.5 showed increase in flow by 19.24% and 16.78% for mid and late century, respectively. For RCP8.5, the increase in flow is 20.13% and 15.86% during mid and late century, respectively. The model was more sensitive towards available moisture and snowmelt parameters. Thus, SWAT model could be used as effective tool for climate change valuation and for sustainable management of water resources in future.

Download Full-text

Assessing Impacts of Climate Variability and Reforestation Activities on Water Resources in the Headwaters of the Segura River Basin (SE Spain)

Sustainability ◽

10.3390/su10093277 ◽

2018 ◽

Vol 10 (9) ◽

pp. 3277 ◽

Cited By ~ 9

Author(s):

Javier Senent-Aparicio ◽

Sitian Liu ◽

Julio Pérez-Sánchez ◽

Adrián López-Ballesteros ◽

Patricia Jimeno-Sáez

Keyword(s):

Climate Change ◽

Land Use ◽

Water Resources ◽

River Basin ◽

Assessment Tool ◽

Forest Area ◽

Se Spain ◽

Monthly Streamflow ◽

Agricultural Areas ◽

Water Assessment

Climate change and the land-use and land-cover changes (LULC) resulting from anthropic activity are important factors in the degradation of an ecosystem and in the availability of a basin’s water resources. To know how these activities affect the quantity of the water resources of basins, such as the Segura River Basin, is of vital importance. In this work, the Soil and Water Assessment Tool (SWAT) was used for the study of the abovementioned impacts. The model was validated by obtaining a Nash–Sutcliffe efficiency (NSE) of 0.88 and a percent bias (PBIAS) of 17.23%, indicating that SWAT accurately replicated monthly streamflow. Next, land-use maps for the years of 1956 and 2007 were used to establish a series of scenarios that allowed us to evaluate the effects of these activities on both joint and individual water resources. A reforestation plan applied in the basin during the 1970s caused that the forest area had almost doubled, whereas the agricultural areas and shrubland had been reduced by one-third. These modifications, together with the effect of climate change, have led to a decrease of 26.3% in the quantity of generated water resources, not only due to climate change but also due to the increase in forest area.

Download Full-text

Application of SWAT model to Assess Land Use and Climate Changes Impacts on Hydrology of Nam Rom River Basin in Vietnam

10.20944/preprints202001.0362.v1 ◽

2020 ◽

Author(s):

Son Ngo ◽

Huong Hoang ◽

Phuong Tran ◽

Loc Nguyen

Keyword(s):

Climate Change ◽

Land Use ◽

Ground Water ◽

River Basin ◽

Climate Changes ◽

Swat Model ◽

Land Use Changes ◽

Hydrological Processes ◽

Water Yield ◽

Hydrological Process

Land use/land cover (LULC) and climate changes are two main factors directly affecting hydrologic conditions. However, very few studies in Vietnam have investigated changes in hydrological process under the impact of climate and land use changes on a basin scale. The objective of this study is to assess the individual and combined impacts of land use and climate changes on hydrological processes for the Nam Rom river basin, Northwestern Viet Nam using Remote Sensing (RS) and Soil and Water Assessment Tools (SWAT) model. SWAT model was used for hydrological process simulation. Results indicated that SWAT proved to be a powerful tool in simulating the impacts of land use and climate change on catchment hydrology. The change in historical land use between 1992 and 2015 strongly contributed to increasing hydrological processes (ET, percolation, ground water, and water yield), whereas, climate change led to significant decrease of all hydrological components. The combination of land use and climate changes significantly reduced surface runoff (-16.9%), ground water (-5.7%), water yield (-9.2%), and sediment load (-4.9%). Overall climatic changes had more significant effect on hydrological components than land use changes in the Nam Rom river basin during the 1992–2015. Under impacts of projected land use and climate change scenarios in 2030 on hydrological process of the upper Nam Rom river basin indicate that ET and surface flow are more sensitive to the changes in land use and climate in the future. In conclusion, the findings of this study will basic knowledge of the effects of climate and land-use changes on the hydrology for future development of integrated land use and water management practices in Nam Rom river basin.

Download Full-text