China
Africa
Explore chapters and articles related to this topic
Classification of Soil Water
Published in A. Zaman, Md. Hedayetullah, Sustainable Water Resource Development and Management, 2022
The downward movement of water through saturated or nearly saturated soil due to the forces of gravity is known as percolation. Percolation happens when water is under pressure or when the tension is less than about 1/3 atmosphere. The conditions of water at a depth stable in such a layer where water goes deep into the soil until it meets the free water table. Percolation studies are important for two reasons: The process of groundwater recharge occurs when it completes percolation. Even water is the only source of recharge of groundwater, which can be again be profitably used through springs and wells for irrigation, sometimes seemed as artesian well in many places.This process also carries plant nutrients like calcium, magnesium deep into lower layers and along with water depositing them beyond the root zone. This process is enhanced in sandy or open-textured soils, there is a speedy loss of water through percolation.
Environmental Problems in Soil and Groundwater Induced by Acid Rain and Management Strategies in China
Published in P.M. Huang, I.K. Iskandar, M. Chino, T.B. Goh, P.H. Hsu, D.W. Oscarson, L.M. Shuman, Soils and Groundwater Pollution and Remediation, 2020
Guoliang Ji, Jinghua Wang, Xiaonian Zhang
Just like the effect of acid rain on soil acidification, generally it is difficult to find direct evidence of the influence of acid rain on groundwater within a short time, because it is a long-term effect that needs years or even decades before any significant damage is evident. This is true in the majority of areas of southern China where industrialization is still in an initial stage. However, acid input into soils can induce the increase in soil acidity, thereby enhancing the leaching loss of nutrients, and particularly the liberation of toxic elements. Such changes in soil properties would influence the composition of percolating water, which in turn would affect the quality of groundwater. A simulation for a watershed in Guangxi Province (Xiong et al., 1993) showed that under the present acid load, soils are in the process of being significant acidified, and that the acidification rate of surface water will be significantly accelerated, if the acid deposition load increases continuously.
Feasibility of Advanced Water Purification Processes
Published in Frank R. Spellman, Land Subsidence Mitigation, 2017
Seasonal variations in each of these values would be taken into account by evaluat- ing the water balance for each month as well as the annual balance. For precipitation, the wettest year in 10 is suggested as reasonable in most cases. Evapotranspiration will also vary from month to month, but the total for the year should be relatively constant. Percolation includes that portion of the water that, after infiltration into the soil, flows through the root zone and eventually becomes part of the groundwater. The percolation rate used in the calculation should be determined on the basis of a number of factors, including soil characteristics, underlying geologic conditions, groundwater conditions, and the length of the drying period required for satisfactory vegetation growth. The principal factor is the permeability or hydraulic conductivity of the least permeable layer in the soil profile.
Assessing the impacts of land use/land cover changes on hydrological processes in Southern Ethiopia: The SWAT model approach
Published in Cogent Engineering, 2023
Hailu Gisha Kuma, Fekadu Fufa Feyessa, Tamene Adugna Demissie
The study findings indicate that alterations in land cover conditions significantly affect the soil’s capacity to hold moisture and infiltration capacity. These changes have a significant impact on the generation of infiltration and runoff. The infiltration and water holding capacity are the most affected soil properties during land-use changes (Akale et al., 2017). Consequently, percolation decreases, leading to an increase in runoff generation, which causes topsoil movement and affects sediment yield. The contribution of annual sediment yield increased by 15.58 metric tons/ha from 1986 to 2002 and then decreased by −0.01 metric tons/ha from 2002 to 2018, which is attributed to increased cultivation land from 1986 to 2002 and a minor decrease from 2002 to 2018. Similar findings have been reported in other studies conducted in different parts of Ethiopia. For instance, Kidane et al. (2019) reported sediment yield rates of 25.8, 28.7, and 30.3 tons/ha/year in the Guder sub-watershed, Central Ethiopia, for 1973, 1995, and 2015, respectively.
Relationships of groundwater quality and associated health risks with land use/land cover patterns: A case study in a loess area, Northwest China
Published in Human and Ecological Risk Assessment: An International Journal, 2019
The thickness, porosity and hydraulic conductivity of the Huanhe aquifer ranges from 40 to 200 m, 0.1 to 0.2 and 0.01 to 0.1 m day−1, respectively (He and Wu 2018). The fissure ratio of the aquifer is ∼0.25. Groundwater in the aquifer is phreatic in the east and confined in the west. The groundwater is mainly recharged from precipitation and river water percolation. It flows from the northeast and northwest of the study area towards the middle and southeast of the study area, and drains into the rivers.