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In situ soil remediation: The reactor approach
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
An ex situ water treatment can be combined with in situ solid-phase and gas or vapor treatment. Water can be collected by a drainage system, extracted by water extraction wells, or just circulated within the soil using groundwater circulation wells (see Section 2.3). Circulation wells can perform in-well water treatment, and purpose-built installations can facilitate out-of-the-well subsurface treatment of the circulated water. Alternatively, extracted water is treated on the surface, (partly) returned or not returned to the soil. The treated water can be re-admitted from the surface through shallow ditches into the unsaturated zone in order to adjust soil moisture or use for continuous or periodic flooding and washing of the solid phase. Water treated ex situ can be directly reinjected into the groundwater, primarily to raise the groundwater level and encourage the groundwater to flow towards the depression wells. Water infiltration systems and injection wells are also used to input liquid, dissolved or suspended additives or reagents. Their transport and distribution are greatly influenced and limited by the sorption (filtering) capacity of the soil and by heterogeneous pore distribution. Gas injection wells can be used for injecting any gas-phase additives (reagents) and hot air or moisture.
Food Security and Nutrition Policy
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
Shafi Noor Islam, Sandra Reinstädtler, Maria Aparecida de SáXavier, Albrecht Gnauck
The convention recognizes that biological diversity is about more than plants, animals, and microorganisms and their ecosystems: it is about people and our need for food security, medicines, fresh air and water, shelter, and a clean and healthy environment in which to live. Upstream fresh water extraction from the river basins, sea level rise, as well as temperature increase are producing harmful soil and water environments in different parts of the coastal regions [46,47]. The present water salinity values are in the range 54,025–69,152 dS/m and the area has been extended from south to north and east to west which is extremely high and threatens the mangrove ecosystem services in the Sundarbans regions as well as in the whole Gorai catchment area in Bangladesh [42,45,47,48]. Dry season salinity along the Nabaganga-Rupsha-Passur river system has largely been influenced by the dry season flow of the Gorai River. The trend of water salinity in the region is at an extremely high rate for the cultivation of agricultural crops and even harmful for animals, fisheries, livestock, and agro biodiversity [46]. As per an earlier soil investigation conducted by Soil Resource Development Institute (SRDI) in 1970, the soil salinity was mainly found in the Ganges tidal floodplain of the study area. This floodplain and the peat basins in the study area were classified as a nonsaline zone. The soil salinity range was between 6001 dS/s to 8644 dS/m during the dry season (November–May) [17,21,46].
Water Soft Path Thinking in Other Developed Economies
Published in David B. Brooks, Oliver M. Brandes, Stephen Gurman, Making the Most of the Water We Have: The Soft Path Approach to Water Management, 2009
David B. Brooks, Oliver M. Brandes, Stephen Gurman
Water extraction is managed and regulated by the EA and distributed between surface and groundwater according to the geology of the region. The densely populated southern regions of England sit on porous chalk and clay aquifers and are therefore heavily dependent on groundwater withdrawals, whereas the reverse applies to the north of the country, which tends to rely on surface water. In the south, the EA has acknowledged that groundwater extraction is now approaching full capacity, with many aquifers exploited to unsustainable levels. Some hydrologists argue that the need for capping, and in some cases even reduction in withdrawal rates, is evident in the majority of English aquifers. Surface water is also under pressure; modelling carried out by the EA suggests that during dry summer periods the majority of English surface water is either already over-withdrawn or that no additional resources can be withdrawn without damaging the environment (EA, 2001).
Unfolding the complexity in water reallocation decision-making in the Heihe River Basin, China
Published in International Journal of Water Resources Development, 2023
Yongping Wei, Shuanglei Wu, Zhixiang Lu, Ray Ison, Andrew Western, Murugesu Sivapalan
Global water demand has increased at a rate of about 1% per year (UN Water, 2018) and water withdrawal has grown 1.7 times faster than the world’s population (FAO, 2018) in the past decades. Excessive water extraction has resulted in substantial and irreversible ecological consequences in several river basins worldwide (Vörösmarty et al., 2010). Recently, a number of river basins, such as the Murray–Darling River Basin in Australia, the Yellow River Basin in China, the Colorado River Basin in the USA and the Erbo River Basin in Spain, have started to reallocate water back to the environment (Dietz et al., 2003; Garrick et al., 2012; Pahl-Wostl, 2015). However, successful cases of water reallocation are relatively sparse, and their expected benefits are rarely met in full (Bouckaert et al., 2021; Marston & Cai, 2016).
The environment comes later: when and how environmental considerations are included in transboundary water agreements
Published in Water International, 2022
Jacob D. Petersen-Perlman, Eran Feitelson
In drier climates where much of the water is extracted and hence basins are stressed or closed, there appears to be a more complicated sequence: Water extraction leads to water stress, possibly even basin closure, creating deleterious effects on the environment. This leads to an environmental agreement. ORWater extraction leads to an agreement focusing on water quantity. The agreement results in deleterious water quality and ecological effects, ultimately leading to an agreement or an environmental amendment to the agreement. This situation is evident in the North American Colorado River Basin, where the basin was over-allocated in previous intranational and international agreements, and both countries agreed on a release of water to mimic seasonal flooding in 2014 (Bark et al., 2016).
Experiments on waste hot water fed still operating with stirring turbulence
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Taranjeet Sachdev, Vivek Kumar Gaba, Mayank Sharma, Anil Kr Tiwari
The presence of life makes earth unique among the celestial bodies and water is one of the essentials for survival of life. Many conventional and advance desalination technologies are already in use for potable water extraction from waste or saline water. The solar-thermal energy reliant passive and active stills have always been a center of attraction due to simplicity of construction, operation, and maintenance. The passive solar still utilizes solar energy directly to heat basin water whereas in active type water is additionally heated by some other means like solar collector and heat exchanger.