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Computational Models for Exchange of Water between Ground Water and Surface Water Resources over a Sub-Basin
Published in Satya Prakash Maurya, Akhilesh Kumar Yadav, Ramesh Singh, Modeling and Simulation of Environmental Systems, 2023
Subba Rao Tellagorla, Subbarao Pichuka
Infiltration is defined as the downward entry of water into the soil and separates precipitation into surface runoff and groundwater recharge (through soil layers). The cracks and macropores on the ground surface are generally assumed to be neglected in mathematical conceptualization to minimize the complexity. At basin scale, the infiltration rate is largely affected by the soil layers based on their physical properties. However, at the local scale, the hydraulic properties, vertical soil profile, soil moisture distribution, and rainfall dictate the infiltration rate. The vertical profile of the subsurface system can be divided into (i) near-surface saturated zone, (ii) transmission zone of unsaturated flow, (iii) wetting zone (where moisture decreases with depth), and (iv) saturation zone. To model the downward movement of water, the soil moisture distribution is approximated using various approaches. The piston-type wetting front movement approach developed by Green and Ampt (1911) is the most widely adopted model for infiltration modeling.
Floodwater Harvesting
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Nasir Ahmad Rather, Shahid Ul Islam, Mir Bintul Huda, Saeid Eslamian
Flood control and water harvesting planning and management are dependent on the rainfall-runoff relationship. It is not only affected by the monthly and annual volume of rainfall but the intensity of rainfall events as well. The relationship depends on the dynamic interaction of rainfall intensity, infiltration of soil, and surface storage. Runoff is caused when the rainfall exceeds the infiltration capacity of the soil. The type of water harvesting structure to be installed and the holding capacity is determined by the rainstorm information over a very long period in that region and its response in the catchment especially in terms of runoff volume.
Runoff
Published in Amithirigala Widhanelage Jayawardena, Fluid Mechanics, Hydraulics, Hydrology and Water Resources for Civil Engineers, 2021
Amithirigala Widhanelage Jayawardena
Runoff is the outcome of precipitation. When the rates of rainfall (and other forms of precipitation) exceed the rates of infiltration, interception and depression storage, the difference emerges as surface runoff. The infiltrated water may also contribute to the total runoff. Components of runoff include surface runoff (overland flow), which is the component that flow over the surface of the catchment, sub-surface runoff, which is the re-emergence of infiltrated water that takes place immediately below the ground surface, and groundwater flow, or base flow. The response time of surface runoff is short, meaning that the time lag between the precipitation and resulting surface runoff is short. The response time of sub-surface runoff component is relatively long, meaning that there is a reasonable time lag between the precipitation and the resulting sub-surface runoff. It is also dependent upon the sub-surface geological and soil conditions. Groundwater flow, or base flow, is the slowest component of runoff. Replenishment takes place through percolation of infiltrated water. The graphical plot of runoff vs. time is called the hydrograph.
Spatio-temporal variations in the ecological vulnerability of the Upper Mzingwane sub-catchment of Zimbabwe
Published in Geomatics, Natural Hazards and Risk, 2023
Bright Chisadza, France Ncube, Margaret Macherera, Tsitsi Bangira, Onalenna Gwate
Hydroclimatic indicators show climatic and hydrological changes. Due to the significant impact of climate variability and change on the environment (Zhang et al. 2021a,b), meteorological indices, especially temperature and precipitation, are crucial for the assessment of EV. Precipitation is a critical component in determining the sensitivity of the ecological environment to anthropogenic and natural risks, as it represents the prevailing weather patterns in a given region (Ding et al. 2018). Annual precipitation is a useful indicator of weather trends that can provide early warning of drought and floods. Precipitation is crucial for soil health and plant growth. The land surface temperature can also help determine weather trends, especially in conjunction with other meteorological variables, such as precipitation, humidity and solar radiation. Temperature rise can destabilise climate conditions and vegetation. Actual evapotranspiration (ET) is also important for determining EV (Nguyen et al. 2019). High evapotranspiration rates cause significant soil and surface water loss, making the ecological system more vulnerable to damage. Runoff is crucial because it ensures that rivers and lakes are adequately supplied with water and changes the terrain through erosion. However, it is closely related to precipitation, slope, soil type, and plant cover parameters.
Analysis of the impacts of land use land cover change on streamflow and surface water availability in Awash Basin, Ethiopia
Published in Geomatics, Natural Hazards and Risk, 2023
Husen Maru, Amare Haileslassie, Tesfaye Zeleke, Ermias Teferi
One of the impacts of the LULC change on streamflow in the Akaki catchment is that surface water increased from 1993 to 2016. The increase in the surface runoff and total water yield could also lead to a climate extreme event – flooding in the catchment. The study also shows that surface water is enhanced in the catchment. There could be two options to manage the excess surface water: utilizing the water for productive purpose and draining it to its final destination properly. In the case of using the water for productive purposes, surface water harvesting and utilizing it through urban agriculture in terms of hydroponics and hydroponics could have a double benefit in utilizing the extra surface water before it causes the problem aiding urban food production. Enhancing the urban areas’ drainage and water disposal system to safely dispose of the generated surface flow to the appropriate area could be another consideration. Unless the surface water is utilized for productive purposes, it could cause flooding, especially in urban areas. In this case, proactive flood management is important to reduce the impacts of flooding on life and property.
Modelling flooding due to runoff from spoil heaps during heavy rainfall
Published in Mining Technology, 2022
Michael D. Bedford, Patrick J. Foster, Michael J. Gibson, Albert S. Chen
Infiltration, in this context, refers to absorption of rain water into the ground, a process that can lead to ground saturation, after which subsequent rainfall will remain on the surface and contribute to runoff. Traditionally, the changing soil saturation with time will reduce the actual infiltration rate. Green-Ampt or Horton’s equations are used to describe the soil infiltration accurately, and include many more variables and require extra computational efforts to solve. In flood modelling, the temporal variation of infiltration has a minor influence on the surface runoff. Thus, in CAFlood, the water is allowed to infiltrate the soil up to a given rate that represents the soil’s maximum infiltration capacity. This simplified approach is able to reflect the infiltration feature adequately without spending too much computing resources on analysing the minor phenomena.