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Harvesting water from the atmosphere is an important process to solve the extreme lack of water resources in arid regions. Adsorption-based atmospheric water harvesting (AWH) takes advantage of solar thermal energy to harvest water from air. This technique is particularly suitable for arid regions characterized by low humidity and an abundance of sunshine. Nonetheless, under low humidity conditions, AWH is highly dependent on water-adsorbing materials exhibiting excellent performance. In this work, a metal–organic framework (MOF), namely [Zn2(bpy) (btec)(H2O)2]·2H2O, also denoted as MWH-1, was investigated for application in water harvesting under low humidity conditions ( 200 cm3∙cm−3; RH = 10%, uptake: >250 cm3∙cm−3). This ensured effective water harvesting at high temperatures during the day. In situ powder X-ray diffraction and Fourier-transform infrared analyses confirmed the sensitive water adsorption process of MWH-1a. The X-ray single-crystal study further demonstrated that single-crystal structures could be completely restored following water harvesting. MWH-1 showed good structural stability and enabled water harvesting under low humidity and high temperature conditions. Thus, it has the potential for application in round-the-clock water harvesting in extremely arid regions.

This study aims to analyze many efficiency-enhancing and improvement activities such as manual and natural cleaning, a PV power plant type rainwater harvesting system, thermal monitoring, and snow load removal in a 600 kW grid-connected photovoltaic (PV) power plant. The study shows that up to 5.66% power reduction can occur for PV modules that have been dirty for close to one year. It was determined that the dust removal effect of the rain was up to 0.94%. This study showed that the potential for collecting rainwater from a small part of the PV plant is approximately 118 m(3)/year and that the harvesting system will reach 1646 m(3)/year when applied to the whole plant. A snow load of 0.117 kN per m(2) was removed. On the basis of three days, 50-75% higher energy production was achieved compared to the other power plant with snow load. Snow removal on PV arrays both prevented PV degradation and resulted in increased power generation, while panel cleaning improved energy efficiency. This study an innovative approach with rainwater harvesting from solar power plants with large surface area for the use in panel cleaning and agriculture of the obtained water, which is a novel idea in increasing the efficiency of the power plants, combating climate change and drought. (C) 2021 Elsevier Ltd. All rights reserved. WOS:000704082300009 2-s2.0-85115356498

The cocoa sub-sector in Ghana is an economically active sector, serving as a major export earner for the country and contributing up to 7% of Gross Domestic Product (GDP). The cocoa value chain in Ghana includes pre-harvest, post-harvest and processing stages, which consist of activities such as seed production, nursery, replanting, cultivation, harvesting, fermentation, drying, scaling and sale, certification and bulking, export or processing. Along the entire chain for all these stages is the intensive use of water and energy, although intensities vary for the different stages. An energy and water mapping was therefore conducted to analyse the energy and water usage along each value chain activity. The studies indicate that mainly rainwater and a little stream and dugout water are used in the pre-harvest stage for nursery activities. The main energy used here is direct sunlight for drying the cocoa beans, manpower used on the farm and about 10% of total petrol and diesel usage along the entire value chain used for transportation during field visits and in tractors for land preparation. During the post-harvest stage, 75% of fossil fuel is used in vehicles and trucks for transportation. The processing stage of the value chain is where the bulk of energy is used, largely from the national grid and about 15% diesel/petrol used in small backup generators and for running processing machineries and equipment. Energy and water estimation and requirements used along each stage in the value chain was conducted. The processing companies, undertaking activities in the processing stage, pay commercial tariffs for water usage (approximately US$1.82 per 1000 litres) and US$0.14 per kWh of electricity usage. The studies showed that besides these high tariffs, which affect production and profits, efficiency levels are very low. The paper concludes that despite the numerous challenges with high cost of production and low efficiencies, there are many opportunities and strengths that can be harnessed to bring about innovation, efficiency and increased productivity along the value chain of cocoa in Ghana. Key amongst these are; collaborating with the vibrant private and public sectors involved in the value chain; harnessing the abundant and high solar radiation to improve drying activities; using the existing regulatory and institutional frameworks to introduce innovative initiatives in the value chain, for example converting the large quantities of organic waste generated from cocoa products production to produce bio-energy; introducing energy efficiencies measures, etc. These, amongst many others, are recommended as opportunities that can be harnessed, together with the enabling environment in the country, to add value to the cocoa sector.

Graphical abstract, Background The cumulative influence of global warming, climate abrupt changes, growing population, topsoil erosion is becoming a threatening alarm for facing food challenges and upcoming global water issues. It ultimately affects the production of food in a water-stressed environment and slows down the production with more consumption of fertilizers by plants. The superabsorbent hydrogels (SAHs) have extensive applications in the agricultural field and proved very beneficial for plant growth and soil health. These polymeric materials are remarkably distinct from hygroscopic materials owing to their multidimensional network structure. It retains a lot of water in its 3D network and releases it slowly along with nutrients to plant in stressed environment. Aim of review A soil conditioner boosts up the topology, compactness, and mechanical properties (swelling, water retention, and slow nutrient release) of soil. The superabsorbent hydrogel plays an astonishing role in preventing the loss of nutrients during the heavy flow of rainwater from the upper surface of soil because these SAHs absorb water and get swollen to keep water for longer time. The SAHs facilitate the growth of plants with limited use of water and fertilizers. Beyond, it improves the soil health and makes it fertile in horticulture and drought areas. Key scientific concept of review The SAHs can be synthesized through grafting and cross-linking polymerization to introduce value-added features and extended network structure. The structure of superabsorbent hydrogel entirely based on cross-linking that prompts its use in the agricultural field as a soil conditioner. The properties of a SAHs vary due to its nature of constituents, polymerization process (grafting or cross-linking), and other parameters. The use of SAHs in agricultural field comparatively enhances the swelling rate up to 60–80%, maximum water retaining, and slowly nutrient release to plants for a longer time.

Seepage well is an emerging Low Impact Development (LID) technology that can effectively control the storm runoff. However, its rainwater infiltration rate and storage capacity still require further enhancement. By setting a horizontal infiltration structure at the bottom of conventional rainwater seepage well (CSW), an enhanced seepage well (ESW) was proposed in this study, and its infiltration performances compared with the permeable pavement (PP) and the CSW were systemically investigated using static infiltration experiment and HYDRUS-2D simulation. The results showed that the infiltration efficiency of ESW was significantly higher than that of PP and CSW, and the process of water infiltrated through soil mainly controlled the macroscopic infiltration rate. The Nash-Sutcliff Efficient (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model, and the results of NSE values greater than 0.75 (varied between 0.75 and 0.91) confirmed the applicability of HYDRUS-2D to describe correctly the hydraulic behavior of the ESW system. Simulation infiltration tests showed that the ESW performed a higher average infiltration rate and fewer total runoff volume than the CSW, indicating the effectively enhancement of the infiltration and water retention capacity of ESW, especially under heavy rainfall intensities. Additionally, the ESW system exhibited an excellent runoff-control and rainwater retention capacity in an actual rainfall scenario.

Dissolved organic matter (DOM) plays a major role in ecological systems and influences the fate and transportation of many pollutants. Despite the significance of DOM, understanding of how environmental and anthropogenic factors influence its composition and characteristics is limited, especially in urban stormwater runoff. In this article, the chemical properties (pollutant loads, molecular weight, aromaticity, sources, and molecular composition) of DOM in stormwater extracted from three typical end-members (traffic, residential, and campus regions) were characterized by UV–visible (UV–vis) spectroscopy, excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC), and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). There are three findings: (1) The basic properties of DOM in stormwater runoff varied obviously from three urban fields, and the effect of initial flush was also apparent. (2) The DOM in residential areas mainly came from autochthonous sources, while allochthonous sources primarily contributed to the DOM in traffic and campus areas. However, it was mainly composed of terrestrial humic-like components with CHO and CHON element composition and HULO and aliphatic formulas. (3) The parameters characterizing DOM were primarily related to terrestrial source and aromaticity, but their correlations varied. Through the combination of optical methods and UPLC-Q-TOF spectrometry, the optical and molecular characteristics of rainwater are effectively revealed, which may provide a solid foundation for the classification management of stormwater runoff in different urban regions.

Rainfall-induced slope failures commonly occur in residual soil slopes. Slope failures are triggered by the reduction in soil strength. This is attributed to the decrease in soil suction due to rainwater infiltration. Slope covers like capillary barrier system and vegetative cover are effective methods that can be used to prevent rainfall-induced slope failures. The capillary barrier system is able to limit the rainwater infiltration, and vegetation can contribute to the increase in soil strength. Vetiver grass is widely planted in tropical and subtropical areas of the world for soil and water conservation. This study investigates the characteristics of unsaturated soil slope covered with capillary barrier system and Vetiver grass in comparison with the original slope through numerical analyses and field measurements. The analyses were carried out under the advanced, normal, and delayed rainfall patterns. The results of the analyses indicated that the capillary barrier system played a more significant role than the Vetiver grass in maintaining slope stability, although both the capillary barrier system and Vetiver grass contributed to the slope stability. In addition, both numerical analyses and field measurements showed that under the delayed and normal rainfall patterns, when antecedent rainwater infiltration could increase the soil moisture, the capillary barrier system performed much better compared to Vetiver grass in maintaining soil matric suctions and slope stability. Housing & Development Board Published version This study was supported by the Housing and Development Board and Nanyang Technological University, Singapore.

The use of a sunken lawn is an emerging Low Impact Development (LID) technique to effectively control storm runoffs. However, the random infiltration of rainwater that occurs due to the construction of a sunken lawn in an area of collapsible loess seriously threatens the safety of buildings around it. Setting up a vertical soil sand layer (VSSL) structure next to a sunken lawn as an anti-permeate method has been proposed in this study. To analyze the lateral anti-seepage effects of a VSSL, a sunken lawn model around a building was established based on soil physical parameters, and water seepage in the sunken lawn was investigated using a infiltration experiment and HYDRUS-2D software. The results show that the anti-seepage effects of a VSSL can significantly reduce the average wetting front migration length and water content at the observation points behind the sand layer. The Nash-Sutcliff Efficiency (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model. The values of the NSE index obtained were greater than 0.82 (varied between 0.82 and 0.98) which confirmed the applicability of the HYDRUS-2D software in accurately describing the hydraulic behavior of the lateral anti-seepage effects of the VSSL in a sunken lawn. Simulation infiltration tests showed that, on the side of the VSSL, the wetting front migration length was reduced by 55.5% on average, and the water content of the observation points behind the sand layer was reduced by 40.5%, increasing the stability of the loess around the building infrastructure. The results are of value in practical applications, such as for devising engineering or non-engineering measures to avoid loess collapsibility around sunken lawns.

In an attempt to identify solutions to the effects of erratic rainfall patterns and droughts that limit agricultural production growth, the Rwandan government has recently increased investments in irrigation development. In this study, we analyze the adoption of small-scale irrigation technologies (SSITs) and its impact on land productivity using cross-sectional data from a sample of 360 farmers in Rwanda. The study uses the propensity score matching technique to address potential self-selection bias. Our results reveal that adoption decisions are significantly influenced by factors such as education, farm size, group membership, gender, extension services, access to credit, access to weather forecast information, risk perceptions, access to a reliable source of water for irrigation, awareness of rainwater harvesting techniques, and awareness of subsidy programs. In addition, the results show that the adoption of SSITs has a significantly positive impact on land productivity. The study concludes with policy implications that highlight the need to promote the adoption of SSITs among farmers as a strategy to improve agricultural productivity and food security in Rwanda.

Slope failures due to heavy rainfall events are phenomena that can cause serious damage to social infrastructures and the loss of lives. Based on previous studies, natural slope failures are generally shallow and originate at the slope toe where infiltrated rainwater has accumulated and saturated it. Hence, it is extremely important to prevent these initial failures from inducing entire slope failures. In the present study, firstly, 1 g model tests, called G series tests, were conducted. In the tests, a gabion filled with filter materials was placed at the slope toe of each model for reinforcement and to drain the accumulated rainwater from the slope toe. Filter gabions have been found to shrink the failure regions and to significantly extend the time until slope failures occur. The failure mechanism in the G series tests was almost similar to that in cases without filter gabions if focus was placed on the slope above the filter gabions. However, the drainage effect was small. Secondly, P series tests, in which a filter gabion with a pipe was introduced for each model, were conducted. The results of these tests indicated that the displacements significantly decreased as the diameter of the pipe and the depth of the pipe’s insertion to the surface layer increased. Water did not discharge through the pipe until the pore water pressure around the pipe reached positive values. The failures always started when a phreatic surface appeared on the slope surface. Thus, it is very important to prevent a phreatic surface from forming on the slope surface. The adequate arrangement of a filter gabion with a drainage pipe may increase the potential for slope stability.

Impressed current cathodic protection (ICCP) is considered an effective method for reducing the corrosion of structures, but is seldom used in the corrosion protection of high-strength steel wires for bridge cables (e.g., stay cable) because the atmospheric environment in which the steel wires are located can barely provide electrolyte solutions for the ICCP system. However, rainwater accumulates on the cable surface and forms rivulets under rainfall conditions, and such rainwater rivulets can be used as electrolyte solutions for the ICCP system of high-strength steel wires. On this basis, this study proposed an ICCP method for high-strength steel wires in rainfall environment and investigated the effects of different protection current densities on the corrosion rate of stay cable steel wires in a simulated dynamic rainwater environment. In this work, the test time and environmental temperature were fixed at 20 d and 28 °C, and a 3% NaCl solution was employed as the simulated rainwater. Corrosion morphologies of steel wires were used to qualitatively characterize the corrosion degree. Weight loss and electrochemical measurements were used to quantitatively characterize the corrosion rate. Scanning electron microscopy and X-ray diffraction were used to analyze the microscopic morphology of corroded steel wires and the chemical composition of corrosion products, respectively. Results showed that in comparison with unprotected steel wires, the surface of steel wires with ICCP were flatter, the number and size of corrosion pits were significantly reduced, and the corrosion rate was significantly reduced. Thus, ICCP played a protective effect throughout the test period; however, the protection efficiency was slightly different under different flow rates. The steel wires were effectively protected at any protective current density under the flow rate of 0.7 mL/min, but were not effectively protected when the protection current density reached 60 mA/m2 under the flow rates of 7 mL/min and 14 mL/min.

Water being one of the classical elements of Earth, is life’s matter and matrix; mother; and medium whose usage rate is always at a hike. The call for conservation of water has always been paramount and there are sundries for conserving it. To reduce the colloidal and shortage of water hitch, the desideratum to conserve water has risen to the next level with the unbalanced water budget equation. In this aspect of interest, Rainwater Harvesting has a pre-eminent role to play and sites the collection and utilization of rainwater and thereby, reducing runoff. A lot of research works and publications dealing with RWH technologies have been insightful. The present paper intends to unearth the various myths and methodologies that are in collaboration with RWH. In addition to the quotidian methods, new flanged technologies will be at a clear glance and the water budget equation balance centralized with examples and cost factors will be explained in a more pellucid way, focusing on the rarity of RWH incorporating the perquisites. High demand of water being a Gordian-Knot, cost-effectiveness along with conservation will be taken into account, thereby proposing suitable and necessary actions with new creative techniques to contrive upon the water as well as energy conservation to meet the apogee demand of water. The cardinal focus of this review paper anent to legitimize water conservation with new creations and the cost-effectiveness of Rainwater Harvesting prudently.

Modern-day technology aims for luxury and comfort in human life by advancement in technology. The revolutionary technological achievement has dramatically enhanced the living standards of a man. Furthermore, the construction industry is one of the largest exploiters of both renewable and non-renewable resources and promotes the use of such technologies strategically for their benefits. However, the implication of these technologies which calls for the use of supplemental technologies, promoting one another that results in increasing energy demand with limited available resources, causing a demand- supply gap resulting into a pressure that leads to stock market graph crashing and economic crisis. Urbanization, due to the growing population takes in more green patches and farmlands causing deforestation and degradation to the biosphere, further causing an increase in disasters and health hazards as a demerit. Hence with urban sprawling and scarcity of open green recreational areas, vegetated green roof has been one effective economic solution. This paper reviews the efforts of various research and review articles, government reports and experiments that emphasis on energy conservation and sustainable environment. The paper starts by describing various components and types of green roofs, and their uses. Thermal insulation, effects of shading and cooling, heat flux and evapotranspiration, reduction of carbon emissions, water savings and, microclimatic conditions are the focus group. As per previous studies, the heat flow in buildings can be reduced by 74%. Green roofs also aide in keeping the building warm during winters while retaining rainwater during the rainfall season also. It also discusses the life cycle assessment as a methodological principle and framework, and its limitations for the analysis of green roof and its passive architecture features.

Summary Recent work has demonstrated adsorption-based solar-thermal-driven atmospheric water harvesting (AWH) in arid regions, but the daily water productivity (L/m2/day) of devices remains low. We developed and tested a dual-stage AWH device with optimized transport. By recovering the latent heat of condensation of the top stage and maintaining the required temperature difference between stages, the design enables higher daily water productivity than a single-stage device without auxiliary units for heating or vapor transport. In outdoor experiments, we demonstrated a dual-stage water harvesting device using commercial zeolite (AQSOA Z01) and regeneration under natural, unconcentrated sunlight where ∼0.77 L/m2/day of water was harvested. Our modeling showed that by further increasing top-stage temperatures via design modifications, approximately twice the daily productivity of the single-stage configuration can be achieved. This dual-stage device configuration is a promising design approach to achieve high performance, scalable, and low-cost solar-thermal AWH.

Sustainable groundwater management by artificial recharge of aquifers has become a possible resolution for increasing depletion and deterioration of groundwater in several river basins across the word. The present study identifies suitable sites to adopt possible aquifer recharge structures in the Vamanapuram River Basin (VRB), South India, where water scarcity and groundwater declines caused parts of the basin to fall in the semi-critical category. The potential of the basin for suitable artificial recharge were investigated by analysing the geo-environmental variables using remote sensing, geographical information system and analytic hierarchy process (AHP) technique. The geo-environmental variables considered for the analysis includes plan curvature, profile curvature, land use/land cover, aspect, distance from streams, relative relief, geology, geomorphology, slope angle, available space for recharge, lineament density, sand percent, rainfall and drainage density. The slope stability assessment and potential recharge zonation was carried out using weighted overlay analysis by assigning the comparative weights to different thematic layers with the help of the multi-criteria decision-making tool of AHP technique. The results of the slope stability analysis were validated using existing slope failure data. The receiver operating characteristic curve (ROC) and area under the curve (AUC) value were used as a performance indicator for the validation of slope stability map. Further, suitable locations in the basin for four site-specific recharging mechanisms viz., rainwater infiltration pits, percolation ponds, injection wells and pond-cum-injection wells were identified using a rule-based approach. It is estimated that an annual volume of 2489.3 Mm3 of water is available to recharge groundwater in VRB, which accounts for nearly 19.2% of the precipitation in the basin. The potential for artificial recharge in VRB is found to be controlled significantly by factors such as geology, geomorphology, slope and available space for recharge. The slope stability analysis shows that about 94.3% of the basin fall under stable zone category and are safe for the construction of aquifer recharge structures, which was further validated with a prediction accuracy of 89.2%. It is estimated that 22,17,639.76 (m3/year) volume of water is available for recharge in VRB; however, the average recharge rates in the basin varies spatially. Western and north-central parts of the basin are found to be suitable for the construction of rainwater infiltration pits and injection wells and percolation ponds respectively, whereas the central parts are found to be suitable for the implementation of percolation ponds and pond-cum injection wells. The outcome of this study can be used for the planning of sustainable groundwater development and regional management of the river basin.

Numerous microbial contaminants persist after the implementation of rainwater treatment strategies, which necessitates the investigation of combination treatment methods. As the development of cost-effective combination treatment methods may aid in increasing global access to safe water, this study aimed to highlight the innovative ways in which existing treatment technologies, such as solar disinfection, may easily be adapted and improved for use in specifically developing countries. In addition, as biological treatment approaches (application of bacteriophages and predatory bacteria) have recently been investigated for rainwater treatment, the advantages and disadvantages associated with the use of these techniques as well as future research needs were reviewed. Finally, the assessment of water treatment systems using molecular-based viability assays was highlighted, as recent studies have reported that these assays may provide a more accurate indication of treatment efficiency (as compared to traditional culture-based analysis), and the data generated can be used in quantitative microbial risk assessment.

In Japan, approximately 64% of municipal solid waste incineration bottom ash (MSWI BA) is landfilled. Because landfills in Japan are operated without capping, the landfill body is directly exposed to climatic events. Increased frequency of heavy rain is predicted to affect the chemical stabilization of bottom ash (BA) landfill, as rainwater seeps into and interacts with landfill components. This study examined the effect of normal rainfall (15 mm/h) and heavy rainfall (25, 50, and 100 mm/h) events on the leaching behavior of ions (Cl−, Na+, K+, and Ca2+) and total organic carbon (TOC) in BA (

Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting (RWH) system can be used as a remedial measure. This study examines the feasibility of rain barrel RWH system at a distributed scale within an urbanized area located in the northwestern part of Chittagong City that experiences flash flooding on a regular basis. For flood modeling, the storm water management model (SWMM) was employed with rain barrel low-impact development (LID) as a flood reduction measure. The Hydrologic Engineering Center's River Analysis System (HEC-RAS) inundation model was coupled with SWMM to observe the detailed and spatial extent of flood reduction. Compared to SWMM simulated floods, the simulated inundation depth using remote sensing data and the HEC-RAS showed a reasonable match, i.e., the correlation coefficients were found to be 0.70 and 0.98, respectively. Finally, using LID, i.e., RWH, a reduction of 28.66% could be achieved for reducing flood extent. Moreover, the study showed that 10%–60% imperviousness of the subcatchment area can yield a monthly RWH potential of 0.04–0.45 m3 from a square meter of rooftop area. The model can be used for necessary decision making for flood reduction and to establish a distributed RWH system in the study area.

This article presents the results of a study on the chemical composition of rainwater as an environmental pollution factor in the surroundings of the Puchuncavi - Ventanas industrial complex (V Region, Chile), with the main objectives of assessing acidification and neutralisation factors, measuring elemental pollutant levels including calculation of enrichment factors and pollution sources assignment, and assessing the risk derived from elemental pollutant loads in rainwater, both for human use and natural ecosystems. Forty-seven weekly rainwater samples were collected during the winter (May–August) 2010 (24 samples) and 2011 (23 samples) at three sampling location with different degree of impact from the main emission sources. The pH, conductivity and major ions were analyzed by ion chromatography, as well as 18 traces and main elements by ICP-MS. Most rainwater samples had pH below 5.6, indicating the risk of acidification, but neutralisation factors, mainly by Na+ and NH4+ were also noticed. The elements emitted by anthropogenic activities had significant enrichment values in the rainwater of the area studied, and the principal component analysis (PCA) identified four sources related to the metallurgical industry – crustal material, marine material, traffic -industry and industrial activities. The risk assessment showed that As content in rainwater is above the WHO guideline value for drinking water at some points in the study area. The contribution of Pb and Cd in rainwater to the soil critical loads turned out to be relatively low, with a maximum of 22.1% for Pb in the vicinity of the industrial complex.

A two-year experimental study on saline groundwater dynamics in the Paraguayan dry Chaco is reported. This study was designed to better understand dryland salinity as a natural phenomenon and a potential consequence of land use changes, in order to avoid adverse economic and environmental impacts. A total of 28 wells at two study sites located nearby Loma Plata were monitored approximately every two weeks for groundwater conductivity and water table level, following transects from sown pasture to native forest and topographic gradients from bush or pasture to a nearby temporarily flooded lagoon. Results show a relation among topography, land cover, precipitation, groundwater salinity and surface salinization. Under pasture, groundwater was less saline in the average and the water table was slightly higher than under adjacent forest. Under forest, infiltrating rainwater never reached groundwater level, whereas under pasture, rainwater diluted the groundwater at several occasions during the observation period. Along the topographic gradients, there was a fringe prone to surface salinization along the borderline of the lagoon. At higher topographic levels, the saline ground water was low enough to not reach the surface by capillary ascension. On the other hand, high water table in the center of the lagoon fed by inflowing rainwaters (which had a slightly higher altitude level than the water table under adjacent land covers), displaced the saline groundwater vertically and horizontally. These findings provide information for land use planning in the region, which is prone to dryland salinity due to a generally high saline water table.

Moist air condensation is a complex process because it relies on numerous significant parameters such as physio-chemical properties of a surface, thermal-physical properties of the moist air, and environmental conditions. Thus, the manuscript intent to structure the model-framework of sustainable water harvesting based on moist air condensation on mesh-like surfaces to increase the availability of potable water. Hence, the significant key factors related to sustainable water harvesting via condensation are identified from extant literature, consultation from researchers, and practitioners and subsequently confirmed by fabricating the experimental setup. Further than, an attempt by applying Total Interpretive Structural Modelling (TISM) is attained to provide a model framework. Thereafter, the procedure for analysis using MICMAC is implemented which performed to categorize the identified factors into the distinct clusters’ dependent on their driving and dependence powers to justify their interrelationship with one another. The research reveals that surface coating, mesh geometry, and material of condensing surface are the most dominant factor in the required hierarchy which helps in improving the condensation rate. Thus, the prioritization of the factors with improvisation intends to fill the gap for scalable, economic, sustainable, and environment-friendly condensation in various fields. This research work can be benefited to the industry to the area of water harvesting and energy conservation. Also, the researchers can consider the most influential factors identified in this research while fabricating experimental setups.

Refereed/Peer-reviewed In a rapidly urbanising world, urban agriculture has garnered much attention for increasing resilience to a range of interrelated stressors, including climate change, food insecurity, economic instability and most recently, public health crises. Critical to understanding the viability of urban agriculture and ensuring its environmental sustainability, is the intersection of available land and the supply of agricultural inputs. Here, we address existing knowledge gaps related to urban agriculture and rainwater harvesting, by quantifying the self-sufficiency potential of half a million homes in Adelaide, South Australia. We developed a model that combines high resolution spectral and LiDAR imagery with productivity and irrigation data that reflect the actual behaviors of urban growers. Results indicate that 65% of residential properties contain enough available land to provide dietary self-sufficiency of vegetables, while capturing and storing adequate rainwater for irrigation, even in the modelled Dry year scenario. The modelled edible garden and associated storage tank would occupy around half of the lawn space in a typical residential block. These results highlight the substantial contribution urban agriculture can make to a more sustainable food systems in a low-density city.

In the past few decades, urban flooding and water shortages caused by the rapid expansion of cities and the destruction of construction ecology have been harshly lost. The current ecological rainwater management system is based on the traditional gray infrastructure and cannot effectively solve the water problems of different scales. Sponge city, as an advanced rainwater management technology, plays a vital role in urban transformation and new construction. While building a sponge city, the gray infrastructure will be integrated to form a gray-green infrastructure integration, and the relationship between water and energy in the sponge city will be coordinated. This paper proposes the problems encountered in the transformation of the gray infrastructure of the sponge city to the green infrastructure and the measures to be taken. The integrated indicator system is used to comprehensively evaluate the integration of the gray-green facilities.

In the arid regions of south eastern Tunisia, the land use is predominated by olive trees cropping, where two main cultivation strategies can be found: using of water harvesting techniques to overcome the scarcity and variability of rainfall (in the Matmata mountains) and dryland farming (in the Jeffara plain). In these arid areas, soil moisture is the main limiting factor for crop growth and it should be monitored to benchmark different management options. Different conventional methods are available for point soil moisture monitoring, but the increased availability of remotely sensed data offers major opportunities for spatial analyses. The aim of this paper is to perform a comparative study on the soil water status for rainfed olive tree growing in three major landscape areas: in the mountains with traditional water harvesting check dams (called jessour), in the piedmont on floodwater harvesting (called tabias), and in the plain with full dryland farming conditions. Time series of Normalized Difference Infrared Index (NDII), derived from Landsat 7 satellite, were retrieved from the novel Google Earth Engine platform. NDII values were related to measured soil water content, which was taken at non-regular time intervals between 2009 and 2017. The analysis of NDII data, indicating the water content of the vegetation, shows that jessour can adequately ensure water supply for olive trees. Increased soil moisture conditions in the jessour areas are visible both in the dry and the humid seasons, indicating the effectiveness of this traditional water harvesting system. Moreover, our results show that Landsat 7 NDII values are correlated with the root-zone soil moisture in the monitoring sites (r2 ranging from 0.62 to 0.67), allowing the use of NDII to estimate soil water contents in our study area.

Exponential growth of water demand and a decrease in usable freshwater due to various climate, environmental and anthropogenic events make rainwater harvesting a useful practice. According to Australian health regulations, drinking rainwater is low risk, if the roof catchment, collection system and storage are well maintained. The CSU Engineering building, which has received an architectural award for its sustainable design, produces its drinking water (3.7 L/person/day) within the premises. Rainwater is collected from the roof catchment, stored outside the building and treated on demand at a fully transparent water treatment plant installed at the entrance of the building. The water treatment facility is fully powered by solar panels installed on the roof. The treatment process consists of several operations, including aeration, sand filtration, GAC adsorption and UV disinfection. The performance of the CSU Engineering water treatment plant for the past 30 months is discussed in this paper. Primary and secondary water quality parameters of treated water were well within Australian drinking water quality standards and showed better results than municipal water available in the host town. The aeration unit improved secondary water quality standards (odor and taste) and the adsorption process was effective for elimination of metals. The result of this experiment indicated that this process could be a promising solution for providing safe drinking water in remote Australia, including sessional demands in rest areas and caravan parks.

Drinking water sources used by largely rural and indigenous communities around Lake Poopo in the Bolivian Altiplano are impacted by drought and a combination of natural and anthropogenic mining-related contaminants putting the long-term health and sustainability of these communities at risk. As an alternative drinking water source, 18 rainwater harvesting tanks connected to corrugated iron roofs, each with a first-flush system, were installed in 5 communities around the lake. The water quality of these tanks was monitored over 22 months and compared to alternative unprotected surface and groundwater sources the communities previously relied upon. The rainwater quality was found to be within the Bolivian and World Health Organization (WHO) limits, except for elevated arsenic concentrations two times the recommended health limit (0.01 mg/L). Tracing arsenic concentrations through the rainwater flow-path showed that the elevated arsenic concentrations result from mineral dust particles entering the system when rainwater interacts with the roof catchment, with arsenic leaching out. A leaching test showed that 24 h of contact time between 200 mL of water and

More than 50 years after the first comprehensively designed projects, the significance of research on past societies and their interactions with landscapes has even increased: Studying arid landscapes opens many areas of general interest about adapted lifestyles and livelihoods, since aridity touches upon problems of desertification and climate change, decentral water and food security. This synoptical paper sheds light onto the premises, functionalities and questions of water harvesting systems in antiquity and asks about the implications of runoff-based economies and societies in the Old World Dry Belt. By comparing results and considerations of the individual contributions to this special issue on ancient water management in general, and water and soil harvesting in particular and other relevant studies, it aims at extracting commonalities and differences between the interlinkages of environmental conditions and human intervention. Moreover, it embeds the various approaches, methods and results of the special issue’s authors into overarching considerations oriented towards achieved results, application-oriented aspects and towards focal open questions. Differential analysis of the studied cases, i.e. systematic evaluation of the differences and similarities increases the understanding of the complex issues of runoff agriculture under various environmental and socio-economic conditions. The relevance of the models of ancient water-harvesting based systems evolved during the last decades for modern challenges is given special regard.

Technology parks promote science, technology and innovation through their components, such as high-tech companies, universities and incubators. They show a significant increase in the number of units, especially in emerging countries such as Brazil. Unlike the industrial and logistic parks that, due to functional requirements, have their pre-determined and standardized architectural and urban characteristics, technological parks have in the innovation, their main characteristic, the possibility of proposing more suitable spaces for urban innovation. The Roof Mosaic is an approach that seeks self-sufficiency in urban areas from the food-energy-water nexus, using rooftops to produce food, renewable energy and rainwater harvesting. The integration between technology parks and Roof Mosaic can be advantageous since their roofs have a lower slope and greater design flexibility than other parks and can, therefore, contribute to the sustainable development of cities. The aim of this paper is to evaluate the potential of technology parks when implementing the Roof Mosaic. A case study underway was used, which is the Federal University of Rio de Janeiro (UFRJ) Technology Park (Rio de Janeiro, Brazil). The results from the case study show the potential for: 100% food self-sufficiency using hydroponic production of lettuces and tomatoes, meeting the demands of approximately 3,300 people; 45.2% for energy generated from photovoltaic panels; and 43% for water reusing rainwater harvesting. The potential of avoided CO2 emissions using rainwater for non-potable purposes, food production and renewable energy, presented of nearly 805 tons of avoided CO2 equivalents.

In recent years, climate change, population growth, and inefficient use of water have exacerbated the water resources scarcity problems around the world. Hence, this paper establishes a new approach of Sponge City construction (SCC) based on water cycle management (WCM) for the sustainable exploitation of groundwater, recycled wastewater and rainwater in the Xi'an Siyuan University. The University is located in an isolated area that is far away from the city center so that no centralized water supply system could be utilized. To mitigate water scarcity problems in the University, 39% of the annual rainfall is harvested and stored from impervious surfaces and grasslands by using the Curve Number (CN) method. This stored water is reused for non-potable purposes: 40% for toilet flushing and 60% as miscellaneous water. According to findings, the available rainwater of500–700 m3/d accounts for 16–23% of the non-potable water from April to December. Moreover, the utilization rate of water resources increases from 204% to 227%. With the minimum volume of large-scale rainwater harvesting cistern of 52,760 m3, the environment could be adequately watered while improving the expansion and development conditions on the campus. Furthermore, water scarcity problems could be mitigated through optimization of the water resources utilization system. This study demonstrates that this new approach of SCC based on WCM could alleviate water resources scarcity problems in Xi'an Siyuan University effectively. It is hoped that this study will provide a model and example of the new approach for future applications.

Greywater recycling and rainwater harvesting have the potential to increase the resilience of water management and reduce the need for investment in conventional water supply schemes. However, their water-savings would partly depend on the location and built-form of urban development and hence its household sizes and rainwater per dwelling. We have therefore tested how spatial planning options would affect the future viability of alternative water supply in the Greater South East of England. Our integrated modelling framework, for the first time, forecasts the future densities and variability of built-form to provide inputs to the modelling of alternative water supply. We show that using projections of the existing housing stock would have been unsound, and that using standard dwelling types and household sizes would have substantially overestimated the water-savings, by not fully representing how the variability in dwelling dimensions and household-sizes would affect the cost effectiveness of these systems. We compare the spatial planning trend over a 30 year period with either compaction at higher densities within existing urban boundaries, or market-led more dispersed development. We show how the viability of alternative water supply would differ between these three spatial planning options. The water-savings of rainwater harvesting would vary greatly at a regional scale depending on residential densities and rainfall. Greywater recycling would be less affected by spatial planning but would have a finer balance between system costs and water-savings and its feasibility would vary locally depending on household sizes and water efficiency. The sensitivity of the water savings to differences in rainfall and water prices would vary with residential density. The findings suggest that forecasts of residential densities, rainfall and the water price could be used in conjunction with more detailed local studies to indicate how spatial planning would affect the future water saving potential of alternative water supply.

Rooftop rainwater harvesting (RRWH) systems can provide low-cost decentralized water to urban and rural households that have no access to treated water. These systems are considered the key strategic adoption measures for communities affected by climate change. Roofing materials, roofing conditions, roofing geometry, weather conditions, and land use/land cover (LULC) conditions can significantly affect the quality of RRWH. Therefore, the effects of these factors on RRWH quality must be analyzed carefully. Remote sensing and Geographical Information System (GIS) have been widely used in urban environmental analysis. However, these technologies have never been used to analyze, map, and model the effect of various factors on RRWH quality. This review determines the research gaps in the use of geospatial technologies in estimating RRWH quality and simulate the implications of roofing materials and roofing surface conditions towards the urban environment. An approach for the integrated use of remote sensing and GIS to assess the quality of RRWH is also proposed. Keywords: Roofing materials, Roofing conditions, Spatial modeling, Environmental impact, Remote sensing, GIS

To evaluate the impact of environmental factors on the deterioration of the historical defensive walls of Cartagena de Indias, a comprehensive analysis of stone and mortars of the structure has been carried out, furthermore through a physicochemical characterization, the role of rainwater and the groundwater on the structural deterioration has been studied as well as for drains and rising damp. SO2, NO2 and PM10 were monitored in order to assess whether air quality is accelerating the deterioration of the structure. Moreover, deposited salts on the walls surface and the distribution of humidity in the structure were studied. Has been shown that limestone is the main stone type of the structure, and mortars probably due to a deficiency on the production process are weak and easily removable. Finally, humidity boundary conditions generated by drainage and rising damp, along with air salinity are the factors that determine the slow decay of the general conditions of the structure.

Pavement drainage Evaluation is conducive to reduce hydroplaning risk. Empirical Water Film Depth (WFD) models are low accuracy and have limited application scope. This study develops an analytical WFD model by simulating the dynamic of sheet flow. Based on the field data of 10 test sites the analytical model and two empirical models are applied for WFD prediction. Refer to the field measured WFD, correlation tests are applied, and the findings include: the intervening factors on WFDs are ranked as follows rainfall intensity, pavement permeability, flow path length, flow path slope, and texture depth; the proposed analytical model is more accurate than Gallaway model and PAVDRN model. The significance is twofold. First, accumulated rainwater is involved in WFD estimation. Second, the hazardous ponding location is identified, so that pavement engineers can take remedial measures to reduce potential hydroplaning.

Water scarcity is a current concern and a future problem. Air-water harvesting (AWH) is a novel proposed solution to provide enough water for human-being's needs especially in remote areas. However, the sorbent material is one of the challenging components of these systems. Generally, a proper sorbent must have a high water uptake capacity, a low regeneration temperature and an easy replacement structure, suitable to deploy in the bed. Here we synthesized three active carbon felt composites with a layer structure and analyzed their potential for being used in AWH systems. The performance of these ACFs composites concerning three different salts was investigated. Experimental results showed that the highest capacity is 2.9 g water per g sorbent at 70% of RH without any leakage. Also, pore parameters, non-equilibrium and equilibrium adsorption, regeneration temperature, recyclability and thermal diffusivity of samples were tested. The thermodynamic cycle of the system is studied, and a three-phase sorption cycle is proposed in this study. The detailed analysis reveals that the presence of the combined use of adsorption-absorption process can improve the sorption capacity extensively. The experimental and theoretical studies proved that these composites are very promising materials for water harvesting applications. To demonstrate these materials capability, a prototype is proposed which adopts these materials as its desiccant. This small prototype automatically could harvest 1.51 g of fresh water per cycle per g of sorbent at RH of 70%, without any human involvement.

[EN] Permeable pavements are part of stormwater management practices known as sustainable urban drainage systems (SUDS). This study describes the influence of several environmental variables, such as the rainfall regime or the pollution build-up level, on the hydraulic and water quality performance of permeable pavements. Four infiltrometers with different configurations of pavement layers were used to study the influence of two rainfall regimes (Atlantic and Mediterranean) and two rainfall intensities (0.5 and 2.2 nn/min). The influence of the progressive pollution build-up level was studied by dry sprinkling of road deposited sediments collected with a mechanical street sweeper with a dose of 5 g/m(2)/d. The results show that permeable pavements retained a significant rainwater volume and improved the infiltrated water quality in terms of suspended solids, organic matter and nutrients when compared to the corresponding surface runoff potentially generated from an impervious pavement. The volume of rainwater retained inside them varied between 16 and 66% depending on the variables studied. The water infiltrated from permeable pavements subjected to a Mediterranean rainfall regime contained, in general, higher concentrations of organic matter (22 to 89 mg Chemical Oxygen Demand/l) and nutrients (0.6 to 2.1 mg Total Nitrogen/l and 0.05 to 045 mg Total Phosphorus/l) than those under Atlantic regime. However, the latter infiltrated higher loadings in terms of mass. Nitrogen was the substance that infiltrated the most, reaching a 25% of the total mass of nitrogen deposited on the pavements surface. The concentration and mass loading in infiltrated water increased as the pollution build-up level did. The leachability of nutrients and organic matter was greater for high rainfall intensities. The results suggest that it is essential to carry out an adequate cleaning in dry conditions, especially when high intensity rainfall events are foreseen, because of its greater capacity to mobilize pollutants., This research was funded through the SUPRIS-SUPeI (Ref. BIA201565240-C2-2-R MINECO/ERDF, UE), financed by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF). Miriam Fernandez-Gonzalvo has a pre-doctoral contract funded by Generalitat Valenciana within the framework of the Program for the promotion of scientific research, technological development and innovation in the Valencian Community (ACIF/2018/111-FSECV 2014-2020). Authors would like to thank the manufacturer QUADRO for yielding paving stones and information on their composition for the research.

Environmental impacts resulting from historic lead and zinc mining in Kabwe, Zambia affect human health due to the dust generated from the mine waste that contains lead, a known hazardous pollutant. We employed microbially induced calcium carbonate precipitation (MICP), an alternative capping method, to prevent dust generation and reduce the mobility of contaminants. Pb-resistant Oceanobacillus profundus KBZ 1–3 and O. profundus KBZ 2–5 isolated from Kabwe were used to biocement the sand that would act as a cover to prevent dust and water infiltration. Sand biocemented by KBZ 1–3 and KBZ 2–5 had maximum unconfined compressive strength values of 3.2 MPa and 5.5 MPa, respectively. Additionally, biocemented sand exhibited reduced water permeability values of 9.6 × 10−8 m/s and 8.9 × 10−8 m/s for O. profundus KBZ 1–3 and KBZ 2–5, respectively, which could potentially limit the entrance of water and oxygen into the dump, hence reducing the leaching of heavy metals. We propose that these isolates represent an option for bioremediating contaminated waste by preventing both metallic dust from becoming airborne and rainwater from infiltrating into the waste. O. profundus KBZ 1–3 and O. profundus KBZ 2–5 isolated form Kabwe represent a novel species that has, for the first time, been applied in a bioremediation study.

For the first time in history, the global population is more concentrated in urban spaces than in rural areas. Population growth, climate change, and increasing stress on water resources evidence the urgency of adopting more sustainable urban water management practices. Drawing on contributions from the literature on informality, Do-It-Yourself (DIY) Urbanism, and urban rainwater harvesting, we investigate DIY Urbanism as a specific type of informality and as a strategy for citizen action to push local governments to adopt and institutionalize water sustainability initiatives. Taking the city of Tucson, Arizona, a pioneer of arid urban rainwater harvesting practices, as a case study, we examine rainwater harvesting as a proposed sustainable urban water management practice for a water-stressed city with aging infrastructure and a growing population particularly vulnerable to a changing climate. Based on interviews, stakeholder meetings, and document analysis, this paper examines several elements of the rainwater harvesting movement in Tucson that both mesh with and differ from other types of informality. We find that although rainwater harvesting contributes to the vision of an urban utopia for some local activists and NGO actors, for those working within the municipal bureaucracy, it may be viewed as an attack on social order and private resource rights. Despite some loss of autonomy in implementing DIY Urbanism after its institutionalization and emerging maintenance issues, DIY Urbanists in Tucson continue to challenge official authority to remake the city. We caution that the subsequent institutionalization of urban rainwater harvesting should not further institutionalize inequities in access but rather promote greater water democracy in cities.

The tritium content of rainwaters and dripwaters was monitored from 2008 to 2016 to determine the age of the dripwaters in Villars Cave, SW-France. Dripwater was collected at two stations, one in the upper gallery and the other in the lower gallery of the cave. Stable isotopes have been monitored at these two stations since 1997. The infiltration time of the rainwater between the surface and the cave galleries was determined using a simple one-dimensional model of the infiltration of recharge waters. The model was forced by monthly precipitation and the concentration of tritium in precipitation reconstructed from the IAEA isotope network and our own measurements in rainwater collected at the Villars site. The age of the dripwaters is 7.0 ± 0.5 years for the upper gallery (∼10 m deep) and 11.1 ± 0.5 years for the lower gallery (∼25 m deep). For the upper gallery where 14C measurements from a modern stalagmite are available, the tritium age is in excellent agreement with the time lag between the start of the bomb 14C peak in the atmosphere and in the stalagmite carbonate. In spite of the shallow depth of Villars Cave, the infiltration time is relatively high, resulting in a substantial dampening of the seasonal to annual isotopic variations. As a consequence, Villars Cave speleothems will archive climate variability at the multi-decadal to centennial and millennial scale.

Urban areas in coastal lowlands host a significant part of the world's population. In these areas, cities have often expanded to unfavorable locations that have to be drained or where excess rain water and groundwater need to be pumped away in order to maintain dry feet for its citizens. As a result, groundwater seepage influences surface water quality in many of such urban lowland catchments. This study aims at identifying the flow routes and mixing processes that control surface water quality in the groundwater-influenced urban catchment Polder Geuzenveld, which is part of the city of Amsterdam. Geuzenveld is a highly paved urban area with a subsurface rain water collection system, a groundwater drainage system, and a main surface water system that receive runoff from pavement and roofs, shallow groundwater and direct groundwater seepage, respectively. We conducted a field survey and systematic monitoring to identify the spatial and temporal variations in water quality in runoff, ditch water, drain water, and shallow and deep groundwater. We found that Geuzenveld receives a substantial inflow of deep, O 2 -depleted groundwater, which is enriched in ammonium and phosphorus due to the subsurface mineralization of organic matter under sulfate-reducing conditions. This groundwater is mixed in the ditches during wet periods with O 2 -rich runoff, and iron- and phosphate-rich drain water. Unlike natural catchments, the newly created, separated urban flow routes lead to mixing of water in the main surface water itself, shortcutting much of the soil and shallow subsurface. This leads to low O 2 and high ammonia concentrations in dry periods, which might be mitigated by water level management or artificially increasing O 2 levels by water inlet or artificially aeration of the main water canals. Further research is necessary how to optimize artificial urban systems to deliver a better ecological and chemical status of the surface water.

Decentralised rainwater harvesting (RWH), greywater recycling (GWR), and hybrid rainwater-greywater systems (HRG) mitigate urban water scarcity at both domestic residential dwelling and commercial building scales. However, few studies have been conducted on HRG in mixed urban water provision schemes under tropical climatic conditions. Thus, this study evaluates and compares the environmental and economic impacts of a centralised mains water system (MWS) against a decentralised RWH, GWR and HRG at a domestic and commercial building using life-cycle assessment (LCA) and life-cycle cost (LCC) analysis under tropical climatic conditions. A functional unit (FU) of 1 m3 of non-potable toilet flushing and irrigation water for a project lifespan of 50 years was used. Results indicate that CML 2001 and TRACI 2.1 methods produce similar results. LCA and LCC indicate that the optimal systems are the commercial HRG and domestic RWH. The commercial HRG has the highest mains water savings (55.3%), lowest environmental impact scores for seven categories, and is the second fastest system to become financially attractive at USD5.20/m3. Similarly, the domestic RWH has the second highest mains water savings (95.3%), lowest environmental impact scores relative to a MWS for seven impact categories, and is the first system to become financially attractive at USD2.00/m3. Sensitivity analysis revealed that global warming, water stress index, and eutrophication are most sensitive to a ∓20% variation in GW and RW energy intensity values at commercial and domestic buildings, respectively. The financial viability of decentralised RWH, GWR, and HRG systems increase with increasing discount rate and mains water tariff, as well as decreasing electricity tariff and installation factor. Financial incentives and subsidy schemes from the Malaysian government may promote uptake of decentralised water systems for mixed urban water provision, as none of the systems were financially attractive otherwise at a discount rate of 6% for 50 years.

The scarcity of freshwater is a growing concern around the world, especially in the developing world and is increasingly threatening human survival in less affluent parts of the world. In arid and semiarid regions, freshwater resources are imperative for the survival of populations as well as development activities in urban centres. Preceding assessments for potential solutions have underestimated the scarcity of water by failing to capture main trends of precipitation and the extent of drought periods. This paper aims to investigate rainfall trends for the City of Windhoek, Namibia. A century scale is examined by reconstructing historical precipitation records, and future trends are subsequently estimated and interpolated using Ordinary Kriging in ArcGIS 10.3. Kriging responds and handles spatial correlation much better for observed data points. The results show locations that receive high rainfall and potential periods for harvesting rainwater. The findings further show that the periods of high rainfall are shorter, and after each high rainfall stretch, a long period of lower rainfall follows immediately. Each low rainfall period is anticipated to last longer than the previous one. These scenarios are highly significant for urban managers in dryland cities such as Windhoek, as they demonstrate when water would need to be extra sparingly managed. This study highlights the need for better water management strategies, if cities in dry climates are to survive the anticipated future water crises.

For considerate use of limited freshwater resources in arid regions, it is very important to recycle the evapotranspiration water in greenhouse production for sustainable agriculture. In addition, in a typical greenhouse, ideal conditions for plants are set at low temperature, which is provided by evaporative cooling systems and ventilation, and this leads to more water waste. In this study, a water harvesting system was devised in the ventilation air path and our simulation for hot months showed that in a large-scale greenhouse, daily 9.5 tons of water is directed out of the greenhouse and 3.3 tons of them can be returned to the system by this device. A case study in a semi-arid area (Isfahan, Iran) showed that this system can provide 50% of water demand in summer. Such a system may provide feasible solutions for low growth yields in water-stressed regions and agriculture-dependent economies.

Inspired by the Stenocara beetle that can collect water from moist air in the Namib desert, here, we propose a simple dynamic control of crystal growth of ZIF on a natural polymer, soy protein. By adjusting the precursor concentration as well as the crystal growth time, hierarchical micro-/nano-crystals are constructed on the protein film surface. Taking advantage of the size difference of such crystals, selectively hydrophobic modification with a low surface-energy agent, stearic acid, can be performed on the surface, creating controllably hydrophilic/superhydrophobic patterns in favor of efficient water harvesting from fog. The effects of the as-prepared patterns on the water condensation behavior and collection efficiency are investigated; the maximum water collection efficiency, notably, can reach as high as 917.6 mg·cm−2·h−1. The results suggest that the biomimetic films hold a potential application in atmospheric water collection and the simple pattern-constructing approach is helpful to develop functional surface-patterned materials.

Green infrastructure and techniques such as rainwater harvesting have been proposed as a means to reduce stormwater discharge in developed areas prone to floods. We examined the effects of rainwater harvesting on discharge cumulatively through the Perdido River drainage network in the US state of Florida, an area prone to routine rainfall-driven nuisance flooding. We considered scenarios where rainwater is stored in parcels with structures that use septic tanks (where tanks are retired and used as cisterns, volume approximately 5.7 cubic meters); and where a similar volume of water is stored at all developed parcels. To evaluate flow reduction through the drainage network, we modeled effects relative to a flow event with a 1.5-year recurrence interval using a spatial GIS-based cumulative-effects model. Our model predicted that retired septic tanks would reduce discharge by more than 10 percent in only a few areas in the study region, almost exclusively in headwater regions and where density of houses using septic tanks is high. Analysis of all developed parcels storing rainwater indicated that discharge in several areas would be reduced by more than 20 percent. Results indicate a spatially variable potential for rainwater harvesting to reduce routine storm discharge. Spatially continuous hydrologic tools such as the one we use here may be especially useful for managers seeking to prioritize limited resources at locations for maximum benefit.

A dew condenser was used to collect dew and frost samples to investigate the chemical properties of dew water for comparison with frost, rain and fog in Nanjing, China during the 2016–2017 winter. Twenty-three separate ambient dew samples were collected at a grassland site in suburban Nanjing, China, from 1st November 2016 to 20th January 2017. Six frost samples, two fog water samples and 13 rainwater samples were also collected for comparative study. Cations (Na+, Ca2+, NH4+, K+, and Mg2+), anions (NO3−, NO2−, Cl−, SO42−, and F−) and pH were detected and measured in all wet depositional samples. In addition, seven kinds of water-soluble ions (WSIs) in atmospheric fine particulates (PM2.5) and atmospheric gas (SO2 and NH3) concentrations were investigated. The field study elucidated that dew water resembles frost water, with WSIs ranked in the order of Ca2+> NH4+> Na+> Mg2+> K+ for cations and SO42− > NO3− > Cl− > NO2− > F− for anions. Most dew and frost samples were alkaline and not as acidic as the rainwater and fog water samples. The mean concentrations of various ions and total ionic content (TIC) in the fog samples were the highest, while the ion concentration ranges in the dew, rain and frost samples were similar. The neutralization strength decreased in the order of NH4+>Ca2+>Mg2+>K+ for the fog samples and decreased in the order of Ca2+> NH4+>Mg2+>K+ for the dew, frost and rainwater samples. A high pairwise correlation between K+, Mg2+ and Ca2+ was observed, which means these cations shared a common crustal source. The SO42−, NO2− and Cl− ions were closely correlated, indicating that the ions were released simultaneously from anthropogenic sources. The low and negative correlations among the NO3−, SO42− and NH4+ ions in the dew water and PM2.5 may imply that fine-mode aerosols have little impact on the composition of dew, which means that the dew water component was dominated by coarse-mode aerosols. The NH3 in the atmosphere plays an important role in dew water due to the strong relationship between NH3 and NH4+.

Leaf litter is an important component of agroforestry ecosystems that plays a key role in soil and water conservation. This study assessed the effect of leaf shape on water interception under controlled laboratory conditions. Two contrasting leaf shapes (needle-leaf, represented by Pinus massoniana; and broad-leaf, represented by Magnolia grandiflora) were placed in a steel box (2 m long and 1 m wide) for separate experiments with different leaf masses per ground area (0.5, 1.0 and 1.5 kg/m2); the steel box was positioned on two different slopes (5° and 20°) corresponding to gentle and steep slopes; the rainfall intensity was 90 mm/h. The results indicated that leaf shapes had specific effects on the interception storage capacity of the leaf litter on a slope. The needle-leaf litter intercepted 2.08 times more rainwater than the broad-leaf litter on average. As the leaf mass increased, the interception storage capacity of the leaf litter successively increased for the needle-leaf litter, while there were no obvious patterns for the broad-leaf litter. This difference occurred because the initially erect broad leaves were easily flattened by raindrop impacts due to their large surface areas and hence formed a horizontal leaf cover (or leaf overlap). This leaf accumulation structure restricted the infiltration of rainwater into the lower leaf litter while providing a short path for rainwater to leave the leaf litter, hence promoting litter flow and leading to less rainwater intercepted by the broad-leaf litter than the needle-leaf litter. Our results provide a better understanding of the effects of leaf shape on leaf litter interception on inclined slopes, which is lacking in the current literature.

Water-retaining pavements are optional and effective to mitigate urban heat island as they stay cool by holding rainwater at the surface layer for evaporation cooling. However, excessive rainfall falling on such pavements will overflow and thus contribute to flooding. Here, we report a novel drainable water-retaining paver block for mitigating urban heat island and simultaneously reducing runoff. The albedo, temperature, water-retaining capacity, and outflow sensible heat of this novel paver block were measured and compared with those of a dense block and a pervious block. The permeability of the water-retaining block was also measured to examine whether this paver block can avoid overflow during heavy rain. Our results showed that the temperature of the water-retaining block in the wet condition can be reduced by 13 °C in the daytime and 3 °C at night, which indicates its good performance of cooling the local air temperature. Our results also indicated that the permeability of the water-retaining block is two orders higher than the precipitation rate of heavy rain, which reveals the excellent performance of quickly draining the excessive water in case of heavy rain.

The considerable potential for rainwater harvesting (RWH) opens the door for the study of economic viability and risk indicators in this kind of system. The aim of this paper was to present economic and risk analyses of three RWH systems intended for water supply to single-family residences. The systems were analyzed based on water demand, degree of treatment and distribution arrangement. Economic, sensitivity and risk analyses were performed. The system with the basic treatment of rainwater and distribution by pressure (BX Pressure) was the most economically viable. The Net Present Value and the Intern Return Rate of the BX Pressure system was 480.36 USD and 6.85%, respectively. In the sensitivity analysis, both basic treatment systems were viable at any considered discount rate (0.00%–10.00%) and at a water price ranging from 1.58 USD to 2.72 USD for BX Pressure. In the risk analysis, BX Pressure was also the most viable system, presenting a risk probability of viability of 95.9% at current water prices. Water price, demand, lower discount rates and initial investment costs determined the greater economic viability and lower economic risk associated with domestic RWH systems.

Potato is a main food crop in the agro-pastoral ecotone (APE) of North China, but its yield is low and highly variable. Agronomic managements, such as irrigation, fertilization and intensive cropping systems, has been used for increasing potato yield but resulted in negative environmental sequences (e.g., soil dryness and groundwater table decline) in such arid and semi-arid regions. This study aims to quantify the agronomic options for better potato production and groundwater conservations based on field experiments together with APSIM-Potato model. The long-term simulated crop yield, economic income and environmental impact (surface soil water content and groundwater table) were analyzed for the different cropping systems of potato (continuous planting, CP; alternating planting and fallowing, APF; long-term continuous fallowing, LF) and irrigation scheduling (rainfed and one-four irrigations). The calibrated APSIM-Potato performed well in simulating the responses of soil water dynamics, leaf area index (LAI), biomass, evapotranspiration (ET) and yield of potato to different irrigation treatments. Long-term (1981–2010) simulated potato yield could be increased by 43.4–90.2% from rainfed yield if irrigation was applied from 60 to 240 mm and the yield gap between the potential and rainfed yields could be narrowed by 41.5–85.9%. Across the APE, CP with four irrigations (240 mm) produced the maximum income of 18,445 Yuan·ha−1 while WUE was the highest for both CP and APF with two irrigations (120 mm). However, such irrigation amounts would decrease the groundwater table by 4.1–42 m across the APE during this period. Rainfed CP could enhance the groundwater table by 0–3 m but decrease available soil water content in 1 m depth by 15.5 mm per decade from 1981 to 2010. Rainfed APF and LF increase available soil water content in 1 m depth by 2–79 mm and 100–143 mm respectively. The study suggested that CP would decrease the soil moisture significantly and increase the risk of soil desertification in the APE. APF with one irrigation by harvesting rainwater could be a feasible way of maintaining soil moisture and groundwater conservation if government subsidy could guarantee the incomes of local farmers in the APE in North China.

Rainwater harvesting has a crucial role in facilitating supplementary irrigation and groundwater recharge. The current research study assesses the socio-economic impacts of small rainwater harvesting structures, Doha Models – percolation tanks dug along the length of lower order seasonal streams, in semi-arid Jalna district of Maharashtra state in India. These structures facilitated recharge of wells in the agricultural fields close to streams. Facilitated by an increased water availability for irrigation, cropping intensity, cropping diversification and crop yields – especially for winter crops requiring assured irrigation – on these agricultural fields grew more than on the agricultural fields away from streams. High risk commercial seed crop cultivation also increased on the agricultural fields close to streams. At two of the four study sites, well recharge led to improvement in drinking water supply and also led to a reduction in physical drudgery associated with fetching water. Ownership and income from livestock also record a growth owing to better water and feed availability for livestock, facilitated by rainwater harvesting. The cost benefit analysis yields an internal rate of return of 16% for Doha Models. However, the study highlights that the benefits from Doha Models are limited to the agricultural fields which are downstream and are close to streams, leaving a large portion of agricultural land. Also, no community institutions are managing these structures. Based on this analysis, the study suggests increasing community participation in the designing and implementation of these structures.