China
Africa
Explore chapters and articles related to this topic
Engineering Hydrology
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Transpiration: This is the process by which the water extracted by the roots of the plants is lost to the atmosphere through the surface of leaves and branches by evaporation. Hence it is also known as evapotranspiration.
Erosion and Sediment Control: Vegetative Techniques
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
Vegetative cover is essential for the design and stabilization of many structural erosion-control devices (Figure 1). Proper vegetative cover provides excellent erosion protection and sedimentation control. Vegetative barriers are planted in close rows along contours on slopes to intercept water runoff, or are planted perpendicular to the direction of wind to retard wind movement, resulting in soil deposition. Plant roots and lateral stems provide a structure to hold soil particles in place. These features also improve the soil’s physical properties and increase infiltration rate, thereby decreasing runoff. Plant transpiration reduces soil moisture levels, which increases soil absorption capabilities. Not every plant material can serve as a soil erosion-control agent. Those plants that do possess some bioengineering characteristics in both the root and the shoot systems that encompass both living plants and organic materials as construction elements for erosion control. Such properties include noncompetition with adjacent crops or fruit trees for moisture or nutrients, a rooting system that reaches deep down to anchor the plant and also extract leached nutrients from the subsoil, and shade tolerance. The plants must be perennials with high seed vigor, have the ability to increase soil organic matter and reduce surrounding soil bulk density to allow faster water infiltration, and have strong woody stalks to withstand pressure from erosive agents.
Transpiration: Water Use Efficiency
Published in Yeqiao Wang, Fresh Water and Watersheds, 2020
Another definition of water use efficiency is in terms of transpired water only. Measuring the transpiration component is hard to do in practice, as it is difficult to prevent soil evaporation. Deep soil drainage also needs to be measured or prevented. It is only possible to measure transpiration on an experimental basis with the use of weighing lysimeters. Typically, the lysimeter is a large pot in the greenhouse and may weigh up to 80 kg. The lysimeter is weighed frequently over the crop season, and known quantities of water are added which is, both costly and limits the practical size of the trial. When extended to field studies (lysimeters within a growing crop), a limited number of comparisons are made due to the setup cost and expense of rainout facilities at sites.
Digital mapping of pesticides bioconcentration by integrating remote sensing techniques and plant uptake model
Published in International Journal of Digital Earth, 2023
Chenyang Xu, Shuangqiao Liao, Minghao Lin, Qian Yue, Jizhe Xia
Plant transpiration describes water movement from the soil to the atmosphere through plant roots, stems, and leaves. It plays a vital role in the bioconcentration processes (Niu et al. 2020). Plant transpiration can be measured mainly using the Sap flow, Charmer, and Biomass-PTs method (Xu et al. 2016; Li et al. 2019). However, plant transpiration cannot be obtained directly from remotely sensed data. Models have been developed to separately estimate plant transpiration and soil evaporation (Li et al. 2019). In regions with full or high canopy cover, ET is mainly determined by plant transpiration, while in sparsely vegetated areas, soil evaporation constitutes a significant fraction of ET (Li et al. 2019). Previous studies have indicated that plant transpiration highly depends on vegetation coverage and the crop coefficient, especially in agricultural areas. Consequently, plant transpiration can be determined by indirectly integrating ET and vegetated parameters through remote sensing techniques (Neale et al., 2015).
Simulation of stream flows and climate trend detections using WEAP model in awash river basin
Published in Cogent Engineering, 2023
As far as the trends of climate data concerned, it was confirmed that precipitation is mainly caused by seasonal variations across the basin. The trends of precipitation in Gewane and Fiche stations were increasing while the trends were decreasing in Sekoru and Bui stations during the study period. Similar findings were reported by (Berhe et al., 2013; Gedefaw et al., 2018, 2019; Hailu et al., 2018). If the trend continues in the future, it could impact the sustainability of water resources recharge. Increasing of temperature also increases transpiration, which increases the chance of rainfall and may interfere groundwater recharge triggered by summer season reduction. Further study will be required to analyze the future water demand beyond this study period and for downstream dwellers. Therefore, an efficient and effective integrated water resources management approach must be implemented based on the results of this study. This study shows that the Awash River Basin’s high water management pressure stems predominantly from demand in irrigation. This rapid rise in demand is not only due to anthropogenic activities but also to changes in precipitation and seasonal variations. Thus, all the basin sections are impacted by the risks and cause conflicts between upstream and downstream dwellers.
Phytoremediation of radioactive elements, possibilities and challenges: special focus on agricultural aspects
Published in International Journal of Phytoremediation, 2023
Gursharan Singh, Surabhi Bhadange, Fnu Bhawna, Pratiksha Shewale, Rahul Dahiya, Ashish Aggarwal, Fnu Manju, Shailendra Kumar Arya
It is the process of immobilizing and stabilizing the toxic elements such as radionuclides and metals from the soil by precipitating it within the roots. Hence, bringing down the bioavailability and mobility of such contaminants by holding it in place. This process includes transpiration and root growth that immobilize the contaminants by reducing leaching, inhibiting soil erosion, maintaining more oxygen levels, and adding more organic matter to the substrate so that it can bind to contaminants. Microbes present near plant roots also assist in the degradation of contaminants (such as pesticides and hydrocarbons) to nontoxic form (Ogar et al.2014). Plant roots secrete some enzymes and proteins, which eventually results in the precipitation and make contaminants immobilized. The advantage of using this method is, it doesn't produce any secondary waste, so there is no need to do any further treatment of it. The Hieracium pilosella can make Uranium immobilize by phytostabilization (Ahsan et al.2017).