Climate Changes and Hydrological Processes

Wang, Wenchuan; Feng, Zhong-kai; Ma, Mingwei

doi:10.3390/w14233922

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…(14) have reported that over 70% of the world's drylands are found in developing countries where inhabitants already face critical challenges related to poverty and food insecurity. In spite of their constraints by water scarcity and high sensitivity to climate change and variability brought about by their extreme ambient temperatures, and with extremes such as droughts and floods projected to intensify, drylands still play a major role globally as they occupy over 41% of the global terrestrial area and support nearly 40% of the world's population, 90% of who live in the developing countries (15,16). Drylands all over the world are known for forage production, making pastoralism a major livelihood activity in these areas.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Rainfall Variability on Streamflow in the Drylands of Northern Kenya: Assessing Water Availability under a Changing Climate

K. Rwigi,

O. Ouma,

O. Ogola

et al. 2024

ijcsrr

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Water availability is a function of climatic and land surface conditions, which determine the amount and distribution of atmospheric water as it reaches the surface. This largely depends on rainfall, whose variability affects water, food and livelihood security. This paper sought to quantify the effects of rainfall variability on water availability in an effort to support effective water resources management. Coefficient of Variation (CV), Standardized Anomaly Index (SAI) and Mann-Kendall trend test approaches were used to assess variability and trends, while correlation and regression analysis were employed to determine effects of rainfall variability on streamflow. A hydrological model, Soil and Water Assessment Tool (SWAT), was used to simulate streamflow with a view to assessing water availability under two climate change scenarios; Representative Concentration Pathways (RCP) 4.5 and 8.5. Results show that the area experiences moderate to extreme rainfall variability, as indicated by CV and SAI values that ranged from 20 to 99% and -2.5 to +3 respectively, resulting in moderate to extreme floods and droughts that often disrupt livelihoods. Current streamflow simulations (1981 – 2020) indicated increasing trends. Near and far future streamflow volumes will decrease by 15% during the April-May-June season while during October-November-December season they will increase by 13%, compared to the present. Increasing trends of rainfall and streamflow indicate that the area has opportunities for rainwater harvesting while the high variability indicates a need for early warning systems to cushion communities from climatic shocks evidenced by the impacts of climate extremes experienced in the area.

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Section: Introductionmentioning

confidence: 99%

Impacts of Rainfall Variability on Streamflow in the Drylands of Northern Kenya: Assessing Water Availability under a Changing Climate

K. Rwigi,

O. Ouma,

O. Ogola

et al. 2024

ijcsrr

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“…Changes in land use tend to alter land surface cover which has a significant influence on the catchment hydrology (12). Pressure on land resources for purposes of providing food, water, and shelter to the ever-growing human population has brought about notable changes in LULC with corresponding impacts on hydrological regimes of watershed areas (13)(14)(15)(16)(17)(18)(19). Among the most notable LULC changes that impact a catchment's surface water yield is deforestation; the permanent alteration of a forest to another on-forest use such as agriculture or urban development (20)(21)(22)(23)(24).…”

Section: Introductionmentioning

confidence: 99%

Effects of Deforestation and Anthropogenic Aspects on Streamflow in the Mau Forest Catchments in Kenya: Hydrological Modelling of Surface Water Yields from Sondu River Basin

Rwigi,

J Kinyanjui,

Mutwiri

et al. 2024

ijcsrr

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Climatic factors determine the amount and distribution of atmospheric water received at the land surface while the land cover conditions determine the partitioning of this water into different hydrological components and ultimately the catchment surface water yields. This study assessed the effects of deforestation of a tropical catchment on surface water yields to address fluctuating flows of the rivers emanating from Mau Forest, the largest water tower in Kenya. Sondu basin traverses Southwest Mau Forest covering an area of 3500 km2. The main channel in the basin flows in a southwest direction into Lake Victoria in an altitudinal range of 2900 to 1130 m a.s.l over a length of 173 km. Different deforestation scenarios over the basin were integrated with climate data to form inputs to a hydrologic model, Soil and Water Assessment Tool (SWAT). Using model outputs, the effects of deforestation on annual and seasonal surface water yields, represented by changes in streamflow volumes under different deforestation scenarios, were evaluated. Deforestation scenarios were derived from a supervised classification scheme of time series of LANDSAT images (1970-2020) to show deforestation trends. Effects of deforestation on the catchment water-yielding capacity were estimated as the ratio of the difference between simulated yields under different deforestation scenarios and those simulated under the pre-deforestation scenario of the 1970s decade. Results show that forest cover declined by 21% and a corresponding growth in land under agriculture by 26% in the period 1970-2020. The decline in forest coverage resulted in an increase in the annual surface water yields of about 23% (from 152 to 187 MCM/year) throughout the period of study. This implies that there is less recharge of groundwater due to decreased infiltration and subsequent storage leading to lower flows during the dry seasons and increased flood frequencies in the basin during the wet seasons. The study has therefore, demonstrated that deforestation has reduced the stability of Mau Forest as a water tower and conservation of the forest will enhance its water-holding capacity thereby ensuring a stable water supply to rivers emanating from it as a way of combating floods and low flows in the basin. The resultant impacts on environment and society are displacements from floods and destruction of properties.

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“…Hydrological models are effective tools for flood simulation, including lumped hydrological models and distributed hydrological models [5][6][7]. The lumped hydrological model regards the basin as a whole and calculates the hydrological processes such as precipitation, evaporation, and infiltration on the surface of the basin.…”

Section: Introductionmentioning

confidence: 99%

The Application and Applicability of HEC-HMS Model in Flood Simulation under the Condition of River Basin Urbanization

Zhang

2023

Water

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With the acceleration of urbanization in a river basin, the changes in the underlying surface structure of the basin are more and more intense, which causes frequent floods. This article aims to analyze the applicability of the HEC-HMS model in flood simulation in urbanization basins and the influence of land use changes on catchment runoff. Pu River Basin is a typical urbanization basin and is taken as the research project. Based on land use changes, soil types, and long-term hydrological data in the Pu River Basin, the HEC-HMS hydrological model is constructed using GIS and HEC-geoHMS. Then, the relative error of flood peak and runoff, Nash–Sutcliffe efficiency coefficient, and correlation are used to evaluate the model simulation rating. The results show that the HEC-HMS model is suitable for an urbanization basin, and its performance grade before urbanization is better than that after urbanization. Finally, sensitivity analysis of nine parameters on model performance shows that curve number, initial abstraction, imperviousness, and time lag are the main parameters. The research results will provide a reference for urbanization basins’ flood simulation and stormwater management.

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Climate Changes and Hydrological Processes

Abstract: Due to the influences of climate changes and human activities, extreme climate events have made obvious changes to the hydrological process and the temporal-spatial distribution of water resources over the past several decades [...]

Cited by 5 publications

References 6 publications

Impacts of Rainfall Variability on Streamflow in the Drylands of Northern Kenya: Assessing Water Availability under a Changing Climate

Impacts of Rainfall Variability on Streamflow in the Drylands of Northern Kenya: Assessing Water Availability under a Changing Climate

Effects of Deforestation and Anthropogenic Aspects on Streamflow in the Mau Forest Catchments in Kenya: Hydrological Modelling of Surface Water Yields from Sondu River Basin

The Application and Applicability of HEC-HMS Model in Flood Simulation under the Condition of River Basin Urbanization

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