Increasing Water Supply Research Articles

Experimental and numerical investigation of the cooling performance of a solar chimney integrated with a humidification system

Solar chimneys are efficient systems for natural ventilation based on thermal principles. However, in regions with high temperatures it may not serve to ensure a comfortable indoor environment. To overcome this challenge, integrating air humidification into the ventilation process becomes necessary. The present study investigates the feasibility of integrating a solar chimney with a humidification setup for evaporative cooling in the climate of Kirkuk, Iraq. This investigation utilizes both experimental and numerical techniques. Numerical simulations carried out using a finite volume approach and validated against the experimental data. The experimental outcomes highlight the effectiveness of evaporative cooling in lowering outdoor air temperatures entering the room from months May to August in the range 5°C–10°C. A parametric analysis of the system indicates that increasing water supply can enhance the rate of evaporative cooling and lower the room temperature while elevating relative humidity. Additionally, higher humidity diminishes air buoyancy, leading to a significant decrease in air changes per hour (ACH) rate. The findings also show that both air changes per hour and water consumption reach their peak at a chimney height of 0.5 m. Moreover, a direct correlation is observed between chimney width and both ACH and water consumption. Expanding the chimney width results in higher ACH and increased water consumption for evaporative cooling. Artificial neural network (ANN) model demonstrates robust predictive accuracy, evidenced by high regression coefficients of 0.9566 for ACH and 0.9505 for room temperature correlated from computational fluid dynamics (CFD) results. This underscores ANN model effectiveness in forecasting system performance under varying input conditions, providing valuable insights for different scenarios and configurations of the system.

Evaluating the spatiotemporal land ecological changes in the Yangtze-to-Huaihe Water Diversion Project area.

As a fundamental component of human existence, land is inextricably linked to human development, and its ecological functions are closely associated with multiple sustainable development goals. This paper presents a framework for constructing and optimizing ecological function space, with the Yangtze-to-Huaihe Water Diversion Project area serving as a case study. A comprehensive land ecological index system is established, encompassing natural foundation, land degradation, land production, ecological structure, and ecological protection. An identity-discrepancy-contrary connection method is employed to investigate changes in regional land ecological functions before (2013) and during (2017, 2020, and 2022) the project's construction based on remote sensing data. The results indicated that the mean values of the land ecological index for each period were 0.1883, 0.1981, 0.2253, and 0.1370, respectively. The study calculated the connection, differences, and contradictions in the land ecological impacts across the counties, revealing a gradual decrease in differences and a growing prominence of contradictions. The land ecology of the Yangtze-to-Huaihe Water Diversion Project area is affected by the project construction, particularly within the construction area, showing an overall improvement. Most counties exhibited a trend of ecological improvement compared to the land ecology before the project's construction. However, after the project implementation, most districts demonstrated a trend of ecological deterioration. As the distance from the construction canal increases, the characteristics of each section and stage vary, generally exhibiting an exponential decrease in the land ecological index. The study highlighted the significance of enhancing the land ecological pattern, improving water quality, increasing water supply along the project, and alleviating groundwater overexploitation. The study can serve as a reference for land ecological protection and restoration in water transfer areas and river basins worldwide.

Effects of long-term saline water irrigation on soil salinity and crop production of winter wheat-maize cropping system in the North China Plain: A case study

Fresh water shortage is a major problem for grain production in the low plain around Bohai Sea in the North China Plain. Relative abundance of shallow saline groundwater could serve as an alternative water resource for use during dry seasons. A continuous 8-year field study was conducted from 2015 to 2023 to assess the effects of salt content in irrigation water on soil salt accumulation and crop production. Fresh water (FW) with electrical conductivity (EC) at 1.6 dS/m and three levels of saline water (SW) with EC at 4.7 (SW1), 6.3 (SW2) and 7.8 dS/m (SW3) were used for irrigation. Results showed that a single irrigation event at the jointing stage of winter wheat increased grain production averagely by 18.6 %, 22.5 %, 12.9 % and 9.5 % compared with a rain-fed treatment (RF) under FW, SW1, SW2 and SW3, respectively. With an additional irrigation applied at flowering stage, both irrigations using FW increased the yield by 28.6 %, and both irrigations using SW2 increased the yield by 19.3 % compared with RF. Negative effects of salt on winter wheat overshadowed the positive effects of increased water supply under two irrigations both using SW. With an irrigation at maize sowing and the subsequent summer rainy season, the yield of maize following winter wheat was not affected by a one-time SW irrigation to the previous crop, but showed a 5.3 % yield reduction when two irrigations of SW were applied. There was no apparent salt accumulation in the top 1 m of the soil profile, but a slight increasing trend in the salt content in the 1–2 m layer of the soil profile under SW2 and SW3 irrigation. No apparent changes in soil physical properties were observed for continuous application of SW. It was suggested that SW with EC not exceeding 6.3 dS/m should be applied for a single irrigation during the winter wheat season. This practice could alleviate the fresh water shortage in this region and allow for the maintenance of a relatively stable yield of winter wheat and maize without the risk of salt accumulation in the soil.

Integrated operation of sand dam and groundwater dam to increase water supply capacity in mountainous areas of Chuncheon, South Korea

Study regionA valley area in South Korea Study focusSand dams are cost-effective water-storage facilities for water-stressed areas in arid and semi-arid climates, with the advantages of reducing evaporation losses and filtering pollutants. Generally, sand dams are constructed by placing a horizontal barrier across the river bed, creating a naturally sand-filled structure upstream. Unlike this typical construction, a sand dam in Korea in the monsoon climate region was built near a mountainous valley, not in a stream, in Mulori, Chuncheon City, to ensure a sustainable water supply throughout the year, and especially to prevent freezing in the winter. Furthermore, a small-scale groundwater dam was additionally constructed downstream of the sand dam to increase the water supply capacity in preparation for severe droughts. In this study, the hydrological reservoir-routing simulations were performed to evaluate the effects of the combined use of the two dams on increasing water supply. New hydrological insights for the regionDaily discharge rates for the period from March 16, 2020 to July 6, 2022 were simulated for several hybrid operations that supplies water primarily through the sand dam under the normal conditions, but combines both water sources to manage severe droughts. The simulated results showed that, compared with operating the sand dam alone, the hybrid operations could satisfy the village’s water demand by increasing the minimum water supply rates by 24.6–50.0 m³/day for different simulation conditions. The combined use of sand and groundwater dams presented in this study will help provide sustainable water supply in water-stressed areas, especially mountainous uplands vulnerable to droughts and freezes.

Use of a low-cost phase change material emulsion in de-centralized thermal energy storage for district heating network enlargement

A detailed heat transfer model of a storage tank was developed to assess the performance of a district heating system with de-centralized storage solutions. The performance of two cases, with water and a low-cost phase change material emulsion as storage medium was analysed for 40 residential buildings in Zaragoza (Spain). The chosen configuration is a typical cylindrical tank with internal coils through which the district heating water flows for the charge and discharge. This decentralized thermal energy storage unit reduced peak demand and mass flow in the network, allowing additional buildings to connect to a saturated grid. Four configurations were examined: (1) A 180 m3 water tank reduced district heating power demand by 36.6 %. (2) The same 180 m3 tank using the emulsion required fewer coils, lowering costs, stabilizing TES temperature, and increasing water supply temperature, thus extending system lifespan. (3) A 130 m³ tank with the emulsion offered operational characteristics similar to the water tank, with economic and structural benefits from reduced size. (4) An 180 m³ optimised tank with the emulsion achieved a 38.8 % reduction in district heating power demand. These configurations demonstrate the efficiency and cost-effectiveness of using phase change material emulsion in thermal energy storage systems.

GOVERNANCE AND WATER LANDSCAPE IN KHULNA CITY: PAST, PRESENT AND FUTURE DIRECTION

This paper examines the water landscape in Khulna City from two perspectives: household water supply and the importance of surface water in the city’s ecology. The authors seek to explore whether the current water supply system can achieve goal 6.1 of the Sustainable Development Goals (Universal and Equitable access to safe and affordable water for all), and the drivers of surface water deterioration and the city’s ecological changes. Both the primary and secondary materials have been consulted. Analysis of water infrastructure and water body encroachments have been explored using remote sensing and GIS tools. Investigation of the water supply networks in Khulna city shows a clear geographical division, where the planned residential and affluent areas enjoy most of the water network coverage. Affluent areas with piped networks and other sources consumed much more water than other parts of the city. Map-based and observational analysis of the Mayur River and Nirala Canal asserts that the water bodies have been encroached severely. About 65% of the total area of the Nirala canal has been encroached on by the government as well as private organizations and individuals. Businesses on and around the Mayur River are booming. As a result, rivers and canals are unable to maintain water flows resulting in higher intensity of water logging and other ecological disruptions. Several recommendations including supply-based water management, hierarchical water tariffs, increasing water supply coverage, the introduction of non-conflicting activities around water bodies and inter-organizational collaboration have been proposed to make the city resilient against the adverse impacts of climate and man-made disruptions.

Impact of Deficit Irrigation Strategies Using Saline Water on Soil and Peach Tree Yield in an Arid Region of Tunisia

Sustainable fruit orchard development in arid areas is severely affected by the scarcity of fresh water. To mitigate the lack of fresh water, the use of low-quality water for irrigation is becoming a common practice in several margin areas. However, salinity is considered one of the most important environmental constraints limiting the successful crop production. Therefore, the effects of deficit irrigation strategies using saline water (3.1 dS m−1) on soil water content, soil salinity, and yield of commercial peach orchard were investigated. Three irrigation treatments were considered: a Control, full irrigated (FI); and partial root-zone drying (PRD50); and deficit irrigation (DI) strategies irrigated at 50% ETc. These levels of water supply allowed for contrasting watering conditions with clear distinction between irrigation treatments. The differential pattern in soil moisture was accompanied by that of soil salinity with an increase in all FI treatments (16–25%). The results indicated that soil salinity increased with increasing water supply and evaporative demand during the growing season from January (3.2 dS m−1) to August (6.6 dS m−1). Deficit irrigation strategies (DI, PRD50) induced more soil salinity along the row emitter compared to the Control due to insufficient leaching fractions. By the end of the growing season, the soil salinity under long-term saline drip irrigation remained stable (5.3–5.7 dS m−1). An efficient leaching action seemed to be guaranteed by rainfall and facilitated by sandy soil texture, as well as the high evaporative demand and the important salt quantity supplied, which maintain the deficit irrigation strategies as valuable tools for water saving and improving water productivity. The significant water saving of 50% of water requirements induced a fruit yield loss of 20%. For this reason, DI and PRD50 could be reasonable irrigation management tools for saving water and controlling soil salinity in arid areas and on deep sandy soil.

Does the South-to-North Water Diversion Project promote the growth of enterprises above designated size in the water-receiving areas?-Evidence from 31 provincial-level administrative regions in China.

The South-to-North Water Diversion Project (SNWDP) is believed to drive the next phase of sustainable productivity growth, meeting growing water demand, so as to address increasing environmental sustainability challenges. The Middle Route of SNWDP is regarded as an extremely large long-distance inter-basin water diversion project, which has benefited Henan, Hebei, Tianjin and Beijing since 2014 with great sustainable changes to the cities, groundwater, ecological environment, industrial structure and social development of the beneficiary areas. Taking the number of industrial enterprises above designated size (IEDS) in the water-receiving areas as the research object, this paper takes the year of policy implementation 2014 as the basic time point, evaluating the change of the number of IEDS in the beneficiary areas of the Middle Route of SNWDP through difference-in-difference model. The results show that: (1) The Middle Route of SNWDP promotes the additional growth of the number of IEDS in the beneficiary areas. (2) When the Middle Route of SNWDP promotes the growth of the number of IEDS in beneficiary areas, there is no regional difference for regions with different development levels. (3) The reasons why the Middle Route of SNWDP contributes to the additional growth of the number of IEDS are composed of promoting mixed ownership reform of enterprises in beneficiary areas, increasing water supply and increasing population. However, the Middle Route of SNWDP has not had a significant impact on the traditional total factor productivity or the components of production factors, technology and capital. From the final outcome, the South-to-North Water Diversion Project has played a facilitating role in the sustainable development of large-scale enterprises in the water-receiving areas.

Development of a Model to Evaluate Water Conservation Function for Various Tree Species

The ecosystem services of forests, such as the water conservation function, are the combined results of diverse processes, and the modification of one part of a forest affects each ecosystem service separately via complex processes. It is necessary to develop an ecosystem service assessment model for various tree species to ensure proper forest management. In this study, a model to evaluate three ecosystem services, namely, the water supply, wood supply, and carbon sink, for various tree species in Japan is developed using many observation data from the previous literature. The integrated evaluation model consists of the forest model, hydrological model, and carbon stock assessment model. The forest model consists of the forest growth model and LAI estimation model, based on allometry. The results of the simulations for the major tree species yield the following findings: (1) Water supply varies with tree species but decreases until about 40 years of age, after which it is near constant. (2) Although beech has a larger LAI than needleleaf forests, water supply is not significantly different. (3) Broadleaf forests are more affected by thinning than needleleaf forests and tend to receive increased water supply as a result of processes such as thinning. This study enabled the evaluation of water conservation function in watersheds containing various tree species.

Implications of climate change on water quality and sanitation in climate hotspot locations: A case study in Indonesia

Abstract Southeast Asia is vulnerable to climate change with over half of its population already being impacted by drought, flooding, and rise in sea levels recently. This work reviews the current water resource challenges in Indonesia, prone to the rising impacts of climate change. A baseline assessment of Indonesia's water and drinking water resources related to its original sources is presented. In response to a growing concern over chronic challenges that undermine water supply nationwide, this study analyses drinking water safety supervision. To accomplish this, a literature survey (100 studies published during the 2000–2023 period) was performed to identify regional groundwater resources sustainability and water security issues. Among the main findings of this study, only 10% of rainfall infiltrates to the groundwater, while 70% of its rivers are heavily polluted by domestic waste. During the study period, water availability decreased to 1,200 m3/year in 2020, with only 35% of the resources being economically feasible for reuse. The water supply deficit in Indonesia was estimated to be 5.5 hm3/year with roughly 67% of the population's water demand satisfied in 2021. Although this deficit might be fulfilled with private vendors, water supply/demand forecasts in 2030 suggest that the gap could not be closed by increasing water supply.

Identifying Regime Transitions for Water Governance in the Yellow River Basin, China

AbstractWater governance determines “who gets water, when, and how” in most large river basins. Shifts in water governance regimes from natural to social‐ecological or “hydrosocial” carry profound implications for human wellbeing; identifying regime changes in water governance is critical to navigating social‐ecological transitions and guiding sustainability. We characterized water governance along with the three main aspects—stress, purpose, and allocation—to develop a quantitative integrated water governance index (IWGI) at a basin scale. Applying the IWGI to the rapidly changing Yellow River Basin (YRB) in China clarifies shifts in water governance between massive supply, transformation governance, and adaptation‐oriented regimes. In the YRB, the underlying causes of regime shifts were increasing water supply and demand before the governance transformation and re‐allocation and regulation after the change. The IWGI offers a comprehensive and straightforward approach to linking water governance regimes to sustainability, providing valuable insights into hydrosocial transitions.

Experimental investigation of an optimized indirect free cooling system including a dry cooler equipped with evaporative cooling pads for data center

Different heat rejection systems could be used to discharge the heat of liquid cooled data center to the ambience. The dry cooler as an indirect free cooling solution is one of the most used, where outside air is applied as a cooling fluid for its finned heat exchangers (FHEXs). In ambiences where dry coolers ambient temperatures are higher than supplied FHEX’s water temperature, evaporative cooling system can be used as pre-coolers. This paper presents an experimental investigation conducted on an indirect free cooling system including a dry cooler equipped with evaporative cooling pads (IFC+EC) under 20 K data center temperature difference for high outdoor conditions, variable fan speed, reduction in cooling pad’s surface and increasing in water supply temperature. The results show that the dry cooler is successfully operated under 20 K temperature difference. Furthermore, by increasing the air speed from 2 m/s to 3 m/s, the pads’ outlet air temperature increases by 0.6 K, the relative humidity tends to decrease about 9% and its efficiency decreases from 97% to 88%. Surface clogging had no significant impacts. A slight rise of 1.24 K in air outlet temperature and a decrease of about 3.3% and 2.5% in relative humidity and cooling pad thermal efficiency respectively were detected while increasing water supply temperature from 23 °C to 44 °C. This allowed authors to propose an optimized IFC+EC system with precooling DC supply water before the dry cooler to reduce its cooling demand by at least 31%.

Were climatic forcings the main driver for mid-holocene changes in settlement dynamics on the Varamin Plain (Central Iranian Plateau)?

Settlement crises in ancient cultures of Western Asia are commonly thought to be caused by climatic events such as severe droughts. However, the insufficient climate proxy situation in this region challenges the inference of clear relationships between climate and settlement dynamics. We investigate the Holocene climatic changes on the Varamin Plain in the context of the climatic history of Western Central Asia by using a transient comprehensive Earth System Model simulation (8 ka BP to pre-industrial), a high-resolution regional snapshot simulation and a synthesis of pollen-based climate reconstructions. In line with the reconstructions, the models reveal only slightly varying mean climatic conditions on the Varamin Plain but indicate substantial changes in seasonality during the Holocene. Increased precipitation during spring, combined with lower temperature and potentially stronger snow accumulation on the upstream Alborz mountains may have led to an increased water supply on the alluvial fan during the vegetation period and thus to more favourable conditions for agricultural production during the Mid-Holocene compared to modern times. According to the model, dry periods on the Central Iranian Plateau are related to particularly weak Westerly winds, fostering the subsidence in the mid-troposphere and hampering precipitation over the region. The model reveals that dry periods have spatially heterogenous manifestations, thus explaining why they do not appear in all proxy records in the wider study region. In fact, the climatic signal may depend on local environmental conditions. The interaction of the topography with the atmospheric circulation leads to additional spatial heterogeneity. Although our results provide several indications for a connection between climate and settlement dynamics, the small overall changes in moisture call into question whether climate is the main driver for settlement discontinuities on the Central Iranian Plateau. To shed further light on this issue, more high-resolution long-term proxy records are needed.

Evolution of Tunneling Hydro-Technology: From Ancient Times to Present and Future

Water tunnels are one of the oldest hydro-technologies for extracting water resources and/or transmitting them through water distribution systems. In the past, human societies have used tunneling for various purposes, including development, as a measure to enable underground resource extraction and the construction of transportation networks in challenging landscapes and topographies. The development of hydro-technology potentially involves the construction of tunnels to feed aqueducts, irrigation and waste water systems. Thus, the ability to make and maintain tunnels became an important component in creating lasting and sustainable water systems, which increased water supply and security, minimized construction costs, and reduced environmental impact. Thus, this review asks how, when and why human societies of the past included tunneling for the development of lasting water supply systems. This review presents a comprehensive overview across time and space, covering the history of tunneling in hydro technology from antiquity to the present, and it ponders how past experiences could impact on future hydro-technological projects involving tunneling. A historical review of tunnel systems enhances our understanding of the potential, performance, challenges, and prospects associated with the use of hydro-techniques. In the past, as the different examples in time and space demonstrate, tunneling was often dedicated to solving local problems of supply and disposal. However, across the world, some features were repeated, including the need for carving through the living rock or digging to create tunnels covered with stone slabs. Also, the world-wide use of extensive and costly tunnel systems indicates the high level of investment which human societies are willing to make for securing control over and with its water resources. This study helps us to gather inspiration from proven technologies of the past and more recent knowledge of water tunnel design and construction. As we face global warming and its derivate problems, including problems of water scarcity and flooding, the ability to create and maintain tunnels remains an important technology for the future.

Evaluating the impact of the Central Chile Mega Drought on debris cover, broadband albedo, and surface drainage system of a Dry Andes glacier

In recent years, Chile has experienced an extraordinary drought that has had significant impacts on both the livelihoods of people and the environment, including the Andean glaciers. This study focuses on analyzing the surface processes of Universidad Glacier, a benchmark glacier for the Dry Andes. Multiple remote sensing datasets are used alongside a novel spectral index designed for mapping of rock material located on the glacier's surface. Our findings highlight the precarious state of the glacier, which serves as a crucial water source for the region. The glacier exhibits locally varied debris accumulation and margin retreat. The most significant impacts are observed on the tongue and secondary accumulation cirques, with the latter at risk of disappearing. The debris cover on the tongue is expanding, reaching higher elevations, and is accompanied by glacier retreat, especially at higher altitudes. The equilibrium line is rapidly shifting upglacier, although the mid-season snow cover still frequently reaches the 2013 equilibrium line, even in 2020. Changes in stream density on the glacier tongue indicate an increased water supply in this area, likely due to enhanced melting of glacial ice. These observed processes align well with meteorological data obtained from reanalysis products. The behavior of dust and debris is influenced by precipitation amount, while the rate of retreat is linked to air temperature.

Water-Energy-Food integrated management model under Uncertainty-A case study of Yulin City

Water, energy, and food are indispensable human survival and development resources. With the rapid development of the social economy, the systematic risk of water, energy, and food is becoming increasingly prominent. Water, energy, and food security are threatened to varying degrees. At the same time, water, energy, and food are interrelated, restricted, and interdependent. It is of great scientific significance to reveal and optimize the WEF (Water-Energy-Food) nexus. This study relied on Chance constrained programming and Fuzzy credibility constrained programming to deal with randomness and fuzziness in the WEF nexus. Meanwhile, based on Bi-level programming, aiming at minimizing water allocation and maximizing system benefits, a Water-Energy-Food Integrated Management Model to deal with multiple Uncertainties, called IMMU-WEF model was constructed. The model solved the critical effects of the randomness of water supply and the subjective fuzziness of water demand on water resources allocation, power generation, primary energy extraction, and food planting area. The results showed that the IMMU-WEF model could efficiently deal with the game between different departments in the resource management system, the random uncertainty expressed by probability density, and the fuzzy uncertainty caused by subjective factors. It can develop a stable management scheme for resource management. Applying the mode to Yulin City, China, it is found that water supply and demand fluctuation dramatically impacts on the WEF system benefit, water resources allocation, energy and food production. Specifically, the system benefit will increase over time, with a total benefit of 1974.04 × 108-1998.06 × 108 yuan (2021–2025), 3065.69 × 108-3100.50 × 108 yuan (2026–2030), and 4128.80 × 108-4191.07 × 108 yuan (2031–2035). Additionally, the system water allocation, primary energy extraction, power generation, and food planting are expected to increase over three time periods. With the increase of water supply in the future, the energy and food production in Yulin City show an increasing trend. It indicates that water shortage will continue to be a major problem in Yulin in the three periods, and that the city still needs to increase water supply and diversion projects to ensure energy security and food security. The results can provide an optimal management scheme for ensuring Yulin City’s water, energy, and food security.

Long-Term Performance of Blue-Green Roof Systems—Results of a Building-Scale Monitoring Study in Hamburg, Germany

For the first time, a long-term monitoring study with different full-scale blue-green roof (BGR) types was conducted. Within a pilot project from Hamburg’s Rainwater InfraStructure Adaptation (RISA) framework, four different BGR types were built in 2015 for long-term evaluation and comparison with each other. The test site was created to find out to what extent BGRs are able to improve hydrological performance and if increased water supply affects vegetation development and species diversity. Therefore, the roofs were equipped with hydrologic monitoring systems, their retention performance was evaluated, and vegetation analysis was conducted. During 2017–2023, between 64 and 74% of the precipitation was retained on the roofs, and in the summer months there was hardly any outflow from the roofs. For single (heavy) rain events, high retention capacities, low outflow intensities, and high detention times were demonstrated. On the BGRs where rainwater is permanently stored on the roof, the vegetation species’ composition changed in the long term, resulting in an increase in biodiversity. The studied BGRs are effective in reducing flood risk from heavy rain events and can increase evaporative cooling and biodiversity. Therefore, such BGRs are a blue-green infrastructure with far-reaching positive effects.

Study on the Cooling Effect of Double-Layer Spray Greenhouse

Greenhouses provide suitable environmental conditions for plant growth. Double-layer plastic greenhouses are often used in many regions to ensure normal crop growth during winter since single-layer plastic greenhouses have poor insulation. However, during summer, the high insulation of double-layer plastic greenhouses, combined with excessive external solar radiation, can cause high temperatures inside the greenhouse that are not suitable for plant growth and require cooling. In this study, we propose a double-layer spray greenhouse using a high-pressure spraying system that is placed inside the double film that allows for additional cooling capacity during the summer in order to sustain plant growth. A greenhouse platform test was set up to investigate the optimum operating conditions for the nozzles and to explore changes in greenhouse microclimate under different nozzle operating conditions. The results show that (1) the cooling rate increases with increasing water supply pressure, nozzle diameter and spraying time, and the humidification rate is consistent with the change in the rate of cooling. (2) The optimal condition for cooling in this experiment is achieved with a 120° double nozzle with a nozzle diameter of 0.30 mm, a water supply pressure of 6 MPa, and a spraying time of 15 min, which can reduce the temperature by up to 5.36 °C and serve as a reference for the summer cooling of the double-layer greenhouse.

Spatial-Temporal Dynamics of Water Conservation in Gannan in the Upper Yellow River Basin of China

Water resources are the material basis for human social development. They play an essential role in human production and life. They are vital for the healthy growth of ecosystem services. The quantitative assessment of the water conservation (WC) function is of great significance to the management of regional ecosystems and the construction of ecological civilization. Gannan is an influential water supply area in the upper Yellow River Basin. Understanding the current status and future changes of its WC function can provide scientific support for the stable use and sustainable development of water resources in the upper Yellow River Basin; its ecological status is highly important. The present study quantitatively assesses the WC function of Gannan based on the InVEST model. It aims to explore the regional ecological compensation mechanism, enhance regional ecological regulation capacity and increase water supply by studying the trend in changes in the WC function and the influence mechanism. The results show that: (1) The overall trend in WC capacity in Gannan increased during the period 2000–2020. (2) The spatial distribution of WC in Gannan varies from year to year, but there is some similarity, showing a high degree in the southwest and a low degree in the northeast. (3) Climatic factors are the dominant factors underlying the spatial and temporal distribution of WC in Gannan. (4) The important areas of WC are located in the southwest and southeast of Gannan.

Determination and eco-friendly suppression of fluoride contamination in ground water samples using activated carbon constituents of carica papaya – A natural adsorbent

A significant contribution to increasing water supply comes from ground water and thereby meets the ever increasing demands for almost 90% of the Indian population. Problems are being faced due to the presence of excess fluoride, arsenic and nitrate in groundwater. It is also observed that low levels of fluoride in ground water can help prevent dental cavities, at the same time, higher levels of fluoride can induce dental fluorosis & skeletal fluorosis. Therefore, the fluoride level in ground water needs to be monitored and strictly controlled. Fluoride levels in drinking water should not be more than 1.5 mg/l, as recommended by the WHO and the Bureau of Indian Standards. The ideal fluoride limit for drinking and cooking is 1 mg/l, while 1.5 mg/l is acceptable if there is no other source available. Therefore, the present study analysis the water samples taken from various bore holes (provided with the locations of water sample using a Global Positioning System (GPS)) for all possible parameters like hardness, alkalinity, pH, TDS, EC, chloride, sulphate and fluoride followed by the removal of fluoride contamination in ground water samples using adsorptive filtration technique with the help of a novel, low cost natural adsorbent (activated charcoal obtained from carica papaya leaves). This work aims to determine and suggest a low cost material (Activated carbon obtained from carica papaya leaves) as an effective natural adsorbent for the defluoridation of ground water using the natural adsorbents in experimental testing. In addition to this, a mobile app for providing the related information and a separate Geographical Information System (GIS) mapping are also done. From the adsorption study, a reduction of about 84% fluoride was achieved. The obtained results were compared with the previously reported results. It is found that the prepared activated charcoal from papaya leaves is highly efficient than previously reported methods. Therefore, for the suppression of fluoride content in ground water samples, an eco-friendly reduction method using papaya leaf charcoal is suggested.