Availability Of Clean Water Research Articles

Potential of nanocellulose for wastewater treatment

Wastewater management has significant interest worldwide to establish viable treatment techniques to ensure the availability of clean water. The specialities of nanocellulose for this particular application is due to their high aspect ratio and accessibility of plenty of –OH groups for binding with dyes, heavy metals and other pollutants. This review aggregates the application of nanocellulose for wastewater treatment particularly as adsorbents of dyes and heavy metals, and also as membranes for filtering various other contaminants including microbes. The membrane technologies are proven to be effective relating to their durability and separation effectiveness. The commercial scale application of nanocellulose based materials in water treatment processes depend on various factors like routes of synthesis, surface modifications, hydrophilic/hydrophobic, porosity, durability etc. The recent developments on production of novel adsorbents or membranes encourage the implementation of nanocellulose based cleaner technologies for wastewater treatment.

THE RELATIONSHIP BETWEEN NUMBER OF FAMILY MEMBERS AND WEIGHT GAIN IN TODDLERS IN THE WORKING AREA OF THE BATU AJI COMMUNITY HEALTH CENTER

Background : The current state of nutrition for the Indonesian people is still not encouraging. Various nutritional problems such as malnutrition and malnutrition, lack of Vitamin A, iron deficiency anemia, disorders due to lack of iodine and excess nutrition (obesity) are still widely spread in cities and villages throughout the country. The factors that influence this situation include the level of family ability to provide food according to the needs of family members, family knowledge and behavior in selecting, processing and distributing food at the household level, the availability of clean water and basic sanitation facilities as well as the availability and accessibility of food. quality public health and nutrition services (Depkes RI, 2007). The purpose of this study was to determine the relationship between the number of family members and the weight gain of children under five in the Batu Aji Community Health Center. Method : This research is an analytical survey or research that tries to explore how and why this health phenomenon occurs. Then analyze the dynamics of the correlation between phenomena or between risk factors and effect factors, by means of a cross sectional approach or collecting data at the same time. This research was conducted in the working area of Puskesmas Batu Aji, Posyandu Tulip Lestari, Posyandu Pelangi, and Posyandu Kasih, the working area of Puskesmas Batu Aji, Batam City. The population in this study were 596 mothers who had toddlers at Tulip Lestari Posyandu, Pelangi Posyandu, and Posyandu Kasih, the working area of Puskesmas Batu Aji, Batam City. Researchers want to measure the relationship between the dependent and independent variables using the Chi Square test. The statistical test criteria used Chi Square. Result : It can be seen that the frequency of the number of family members most of the members of the extended family is 62 people (62%). that there are more respondents who have children above the red line as many as 71 people (82.6%). Chi-Square obtained a p-value of 0.542 because the p-Value> 0.05 means that Ho is accepted Conclusions :It is known that there is no relationship between the number of family members and body weight under the red line for under-five children in the working area of the Batu Aji Health Center, Batam City with a p value = 0.542

Haiti's Cholera Epidemic: When the Unexpected Must be Expected

Cholera has been around for centuries but in our modern history there has been a resurgence with at least 7 devastating global outbreaks occurring worldwide in in the last century each claiming thousands of innocent lives. Cholera infects 1.3 to 4 million people around the world, killing 21,000 to 143,000 people annually according to the World Health Organization (WHO). It is thus imperative to research this bacterial disease and come up with ways of shedding light on effective prevention and cure. Cholera is an illness of multi-causal origin where biological, environmental, social, political, and cultural factors intervene. This disease continues to resurge as a sanitary problem of great magnitude in many countries and emerged in Haiti following the January 12, 2010 magnitude 7.0 earthquake some 16 miles from the capital city of Port-au-Prince, where it caused massive damage to roads, buildings, and the environment. Although Haiti is among the poorest countries in the Americas, and its capital city lacked much in the way of modern public sanitation at the time of the earthquake, the country had been cholera free for at least 150 years or more at the time of the earthquake. By mid-October 2010, the first cases of cholera began to appear, and by the end of the decade would infect some 800,000 Haitians (~10% of the population of Haiti) and approximately 10,000 deaths. The source of the infection was traced to the Artibonite River, a main source of water in Haiti, which was believed to have become unknowingly contaminated by well-intentioned foreign workers from Nepal following the earthquake. The strain of cholera found in Haiti was similar to the one found in Nepal (CDC). Haiti employed measures of Cholera prevention and eradication efforts including water treatment, sanitation and hygiene measures, education, oral vaccination, and addressing climate variability issues, history, epidemiology, clinical diagnosis, and treatment, monitoring and prevention of this disease to prevent further loss of life. By 2020, no new cases of cholera have been reported for over 12 months, indicating that Haiti may soon be cholera free once again. Results/Conclusion: Effective hygienic conditions, timely medical intervention including supportive care, access to the appropriate antibiotics, availability of clean drinking water, hand washing, and other prevention protocols can help curb the loss of life associated with cholera. Cholera can kill a healthy person within 12 to 24 hours from the onset of diarrhea, as it is quite virulent. The current situation of cholera in the world (particularly in Haiti), and the extensive collaborative relation and the geographical proximity to Haiti makes the epidemiological risk in neighboring countries increase; therefore, immediate action is required in the organization of health services to prevent yet another epidemic.

Urbanization: an increasing source of multiple pollutants to rivers in the 21st century

Most of the global population will live in urban areas in the 21st century. We study impacts of urbanization on future river pollution taking a multi-pollutant approach. We quantify combined point-source inputs of nutrients, microplastics, a chemical (triclosan) and a pathogen (Cryptosporidium) to 10,226 rivers in 2010, 2050 and 2100, and show how pollutants are related. Our scenarios consider socio-economic developments and varying rates of urbanization and wastewater treatment. Today, river pollution in Europe, South-East Asia and North America is severe. In the future, around 80% of the global population is projected to live in sub-basins with multi-pollutant problems in our high urbanization scenarios. In Africa, future river pollution is projected to be 11–18 times higher than in 2010, making it difficult to meet Sustainable Development Goals. Avoiding future pollution is technically possible with advanced wastewater treatment in many regions. In Africa, however, clean water availability is projected to remain challenging. Our multi-pollutant approach could support effective water pollution assessment in urban areas.

Study of the potential use of rainwater as clean water with simple media gravity filters: A review

Clean water plays an essential role in all living things. However, the availability of clean water in Indonesia is insufficient to fulfill the total need for clean water, especially during the dry season. One of the alternative sources of clean water is rainwater. This study aims to understand the characteristics of rainwater in Indonesia as well as the effect of the variations of type, arrangement, and thickness of the simple filter media on the rainwater in Indonesia. A literature study from several studies is conducted regarding the use of rainwater as clean water with filters made from simple media to improve clean water by utilizing gravity filtration technology. The key descriptors used in this review include “rainwater filtration”, “filtration”, “rainwater harvesting” and “media filtration”. The quality standard used in this study is based on the Ministry of Health Regulation No.416/Menkes/Per/IV/1990. Based on the literature, simple filtration technology can significantly reduce some parameters value where the value of efficiency is more than 50% for parameter turbidity, TDS, Pb, arsenic, total coliform, hardness and nitrate. However, it has not been able to reduce the parameter of sulfate, nitrite, chloride, magnesium significantly. The review shows that the filter medium that is effective and easily accessible are gravel, zeolite, activated carbon, sand, cotton, sponges with a total media thickness of 20 cm, 70 cm, 80 cm, 100 cm, and 105 cm and the time required to perform the filtration is about 10-15 minutes.

Integration of Village Development with the Company’s CSR Program in the Environmental Priority Program Formulation

The village development program is still prioritized for infrastructure development and less community development. On the other side the company’s CSR program is still not in line with the village program so it is less a solution to the community’s problems. This study aims to identify environmental problems around the work area of Labuhan Sumbawa PLTD and determine short-term environmental priority programs that are integrated with the village development program. The method used is social mapping and need assessment. The results showed there were five problems on environmental aspects, namely the problem of garbage, the availability of clean water, air pollution, noise in the area around the Labuhan Sumbawa PLTD and the problem of greening. Formulation of priority programs that are integrated with Labuhan Sumbawa village development program including the provision of clean water networks, procurement of waste management infrastructure facilities, training and assistance on household scale waste management and clean water treatment training as well as greening and procurement of Green Open Space (RTH).

Iron (III) doped titanium dioxide coated dimensionally stable graphite anode electrode for electro-chemical treatment of domestic wastewater

Availability of clean water is of concern due to pollution and diminishing supply pollution. However, purification is possible depending on the incorporated contaminants. Domestic wastewater contains dissolved organic matter and its remediation can be done by oxidation. The best oxidation can be achieved by electron transfer the same way metabolic processes occur. This study exploited the use of a film of iron (III) doped titanium dioxide applied on an electrode which was found to be effective. Natural light conditions generated electrons that migrated through the electrode leaving behind holes which oxidized the contaminants as the excess electrons were discharged at the cathode after passing through the casted proton exchange membrane (PEM) separating the two half cells of the prepared reactor. This electrochemical method has the advantage in that the organic pollutants are oxidized to carbon dioxide with no secondary pollutants and the inorganic pollutants into insoluble matter. The assembled cell was applied to purify both synthetic and real water samples of green leafy vegetable solution from the kitchen by clarification. The clarification process was monitored by UV-Vis using distilled water as a reference to compare the light that transmitted through a sample. It was observed that the electro-oxidation process took place showing a high potential 105 mV within the first 150 min followed by degradation at a high rate. The oxidation of the organic matter was confirmed by UV-Vis analysis as well as by cyclic voltametric analysis of iron released into the solution of the synthetic samples. The electro chemical treatment of the water was then applied to purify real water samples made from a sample of 4.5 g minced of green vegetables dispersed in one liter of water (4.5 g/l). The green leafy coloured solution was clarified after 154 h of continuous oxidation. The degradation process was confirmed to be independent of intermediates or other species present in solution as it was of first order reaction kinetics. The electrochemical oxidation of organic matter in water using iron (III) doped titanium dioxide coated graphite electrode has potential application on the purification of water.

Impact of the Sunda Strait tsunami on fish production and environment in South Lampung Regency, Lampung

The tsunami impact on capture fisheries production and environment in the area of South Lampung Regency of Lampung Province is necessarily assessed. This study aimed to analyze the impact of the 2018 Sunda Strait Tsunami on capture production and environment. The study was conducted from January to March 2020 in Way Muli Village, Rajabasa Subdistrict, South Lampung Regency through the case study method. The data used in this research consisted of primary and secondary data. The method of data analysis applied was the quantitative and qualitative method. The result of the study indicated that the Sunda Strait Tsunami negatively affected the quantity of fish captured by fishermen. In average, capture production decreased from 41.35 kg/month to 16.35 kg/month or approximately 60.5%. The Tsunami also caused a negative impact on the environmental aspect, namely declining clean water availability, damaged village infrastructure, poor environmental sanitation, damaged fishing settlement, and damaged fishing support facility. The support from multi-stakeholder is also needed to increase capture production through the reconstruction of the damaged fisheries facility and infrastructure due to Tsunami. Moreover, it is required to establish a multistakeholder integrated partnership to solve problems of environment and infrastructure in Way Muli Village following the Tsunami disaster.

Analyzing the Risk to COVID-19 Infection using Remote Sensing and GIS.

Globally, the COVID‐19 pandemic has become a threat to humans and to the socioeconomic systems they have developed since the industrial revolution. Hence, governments and stakeholders call for strategies to help restore normalcy while dealing with this pandemic effectively. Since till now, the disease is yet to have a cure; therefore, only risk‐based decision making can help governments achieve a sustainable solution in the long term. To help the decisionmakers explore viable actions, we propose a risk‐based assessment framework for analyzing COVID‐19 risk to areas, using integrated hazard and vulnerability components associated with this pandemic for effective risk mitigation. The study is carried on a region administrated by Jaipur municipal corporation (JMC), India. Based on the current understanding of this disease, we hypothesized different COVID‐19 risk indices (C19Ri) of the wards of JMC such as proximity to hotspots, total population, population density, availability of clean water, and associated land use/land cover, are related with COVID‐19 contagion and calculated them in a GIS‐based multicriteria risk reduction method. The results showed disparateness in COVID‐19 risk areas with a higher risk in north‐eastern and south‐eastern zone wards within the boundary of JMC. We proposed prioritizing wards under higher risk zones for intelligent decision making regarding COVID‐19 risk reduction through appropriate management of resources‐related policy consequences. This study aims to serve as a baseline study to be replicated in other parts of the country or world to eradicate the threat of COVID‐19 effectively.

MEMERANGI KEMISKINAN MELALUI PARTISIPASI PENDIDIKAN DAN AIR BERSIH PADA KABUPATEN DAN KOTA DI INDONESIA

The purpose of this study is togive the alternative solution to the regime about the new model of extention that increased literacy, education participation, and access to clean water in reducing poverty disparities.The methodology used was an econometric approach with a multiple regression equation model with robustness provisions. The data analyzed in this study covered 501 districts and cities throughout Indonesia in 2018. The calculation results prove that the model has been robust and all variables selected have a significant effect on the degree of freedom of 5% for all districts and cities in Indonesia. The results of this study suggest that education policy priorities, the avail-ability of clean water and adequate distribution are needed to reduce the poverty gaps.

Towards an Autonomous and Smart Water Tank System

Water is a mandatory need for all human beings. Without water, life is not possible. The increasing population of the world has an inverse relationship with the availability of clean water. It is used for different purposes e.g., drinking, washing, cooking, agriculture, industries, etc. It is one of the precious natural resources. Unfortunately, excessive use and wastage lead to serious circumstances for other consumers. The major causes of the wastage are overflow in overhead tanks, damaged pipelines, open and faulty water taps and valves, and unnecessary consumption. Dry running of the water pumps is another important issue concerning water pumps. When the water from the main pipeline is not reaching them or the flow rate of water is too low, the water pump will consume more electric supply, which shorten their working span. On the other hand, inappropriate voltage is also damaging the water pump motor. The drinking water with an average quality of purity is responsible for a healthy nation. The water with inadequate levels of pH and turbidity can invite water-borne diseases. After considering all the problems, a need for proper solutions is highly recommended. In this regard, we found an adequate solution in the form of an autonomous system called Smart Water Tank. Our intention is not limited to overcome the wastage of the water only but also to control the unnecessary use of resources-electricity and water pump, the monitoring of drinkable water quality concerning pH and turbidity level. This flexible, portable, and economical automated system will be responsible for automatically switching ON/OFF the water pump motor, monitoring the water flow rate, electricity magnitude, and its temperature-needed for the water pump motor, during and before it takes starts for filling. All the updates for the different parameters will be displayed by the LCD and LEDs installed on the system-locally as well as on the smartphone app connected with Smart Water Tank System via server.

Customer Satisfaction and the Willingness to Pay for Cleaner Water to Sustain Clean Water Supply in Bengkulu City, Indonesia

Clean water is a basic human need. One of the drinking water supply systems is held by a regional drinking water company. Business profits of regional drinking water companies are crucial things that allow companies to continue to exist in business and expanding the service to supply clean water to the wider community. Ensuring availability and sustainable provision of clean water is important since it has been targeted in Goal 6 of Sustainable Development Goals. The existence and continuity of business activities are very inseparable from service quality and customer satisfaction. Therefore, customer satisfaction and willingness to pay for clean water supply are essential factors for the company's continuity and the sustainable management of clean water for the community. The study aimed to determine the level of customer satisfaction for the provision of clean water and to uncover the factors affecting the community's willingness to pay to improve clean water delivered. The method for getting customer satisfaction index used Structural Equation Modelling and indexing. Contingent valuation method and logistic regression were employed for analyzing willingness to pay and uncover the factors affecting it. The results showed that the overall customer satisfaction level was moderately satisfied with a Customer Satisfaction Index of 66 with priority improvements to increase customer satisfaction, especially on attributes of turbidity conditions of water, water quality assurance, and water price level. The result indicated that fifty-six percent of the respondents are willing to pay for cleaner water. The only factor influencing the willingness to pay for the cleaner water supplied is the average monthly water bill

A Qualitative Analysis of Factors Influencing Household Water Treatment Practices Among Consumers of Self-Supplied Water in Rural Ethiopia.

BackgroundThe health of a community depends greatly on the availability of sufficient and clean water. Rural households relying on self-supplied drinking water must take full responsibility for the treatment of their drinking water. Globally, not many inquiries appear to have been carried out to satisfactorily inform us regarding how and why improvements in behavior related to water treatment occur in some selected individuals and not in others. Related investigations in Ethiopia are even fewer.MethodsIn the rural Aleta Wondo district of Ethiopia, a total of fifteen focus group discussions were conducted with community members. Similarly, ten key informant interviews were conducted with officers responsible for organizing water and hygiene programs. To gather data for this study, two qualitative data collection methods, viz., key informant interviews and focus group discussions, were used. Open code software 4.03 was used for thematic analysis.ResultsFactors influencing household water treatment practices were categorized into individual-level factors (eg cognitive factors, emotional factors), household-level factors (household means and decision-making balance), community-level factors (the value that is given for water quality and Public resources) and, environment and context-related factors (access to products and reliance on external sources).ConclusionHousehold water treatment practice has a range of multilevel influences. Beyond the model of providing ongoing safe water education by health extension workers, potential initiatives could be improved by community mobilization activities that include community leaders, women’s groups, etc., in promoting water treatment at community engagements. Also, the results of the present study indicate that it could be beneficial to provide health extension staff with additional training to improve their ability to encourage community members across, a wide range of user types or levels of readiness, to treat their water.

Opportunities and Challenges Application of Desalination Technology for the Clean Water Availability in Bangka Islands

Bangka Belitung islands is a province with limited clean water due to a lot of tins mine which is not environmentally friendly. on the other hand, Bangka Belitung has a 1200 km coastline more easily to access seawater. for this reason, the desalination technique is used as a way to overcome the limitations of freshwater. In addition to answering the needs for clean water, desalination techniques can also answer the need for salt on the island of Bangka by utilizing brine as waste from the processing of desalination techniques. this study applies the interpretive structural modeling (ISM) method which is based on several criteria such as social, economic, and environmental considerations in assessing the opportunities and constraints of implementing seawater desalination techniques. Result shows of the hierarchical analysis, the main challenges in desalination technique are high operational costs, distribution, and access to water resources and a regulatory framework that has not yet been established. the main opportunities in the desalination development are raw materials (seawater) are easy to access, environmentally friendly technology and support from local government.

Sanitation Environment and Helminth infection in Gowa District, Indonesia

Healminth infection is one of the environmentally-based diseases which is a problem for public health. This research was conducted to know the description of latrines, trash bins, and clean water victims for people with healminth infection in the working area of the Kanjilo Health Center. This research uses quantitative research methods with a descriptive survey approach. The research sample was 32 samples. The data used are preliminary data from the medical records of the Kanjilo Health Center, Gowa Regency, while the data source used is secondary data. Data analysis using data processing research with SPSS. With a frequency distribution approach. The results showed that the worms that occurred were in a bad category, including 8 respondents who vomited worms and 24 who suffered from healminth infection. The results of this study found that both the availability of latrines, the availability of clean water and landfills, were all in the bad category, causing worms and vomiting in the community in the working area of the Kanjilo Health Center.

Population health risks in multi-hazard environments: action needed in the Cyclone Amphan and COVID-19 – hit Sundarbans region, India

ABSTRACT The local population of Sundarbans, an environmentally vulnerable delta region in south-eastern India, is currently affected by combined negative impacts of cyclone Amphan and the COVID-19 pandemic. The lockdown measures have created an additional burden on the health care system, while flooding during Amphan increased the risk of spreading water-borne diseases. In this viewpoint, we provide a conceptual model of the complex interlinkages among the combined multi-hazard effects, human health and water availability, with possible mitigation measures. We then discuss the specific pathways through which these immediate and long-term impacts occur and highlight the risk of together slowing progress on SDG3 and SDG6 in the Sundarbans. Finally, we call for coordinated assessment, support and appropriate intervention measures to secure clean water availability and minimize the health impacts of the recent multiple disasters in this tropical delta region.

Fundamentals, synthesis, characterization and environmental applications of layered double hydroxides: a review

The availability of clean water and energy scarcity are rising issues in the context of rising population and industrialization, calling for advanced methods of remediation and energy production. Here, layered double hydroxides, as anionic clays, can be used and engineered as adsorbents or catalysts. Layered double hydroxides are generally highly stable, safe and recyclable. They can be filled with nanomaterials to form composites of enhanced performance. Here, we review fundamentals of layered double hydroxides, synthetic protocols, and applications to energy storage, dye degradation, organic pollutant degradation, water treatment, photoelectrochemical water splitting and carbon dioxide reduction. Composites appear competitive in terms of low-cost, tunable band-gaps and high electrical conductivity.

Experimental Studies on Continuous Electrocoagulation Treatment of Peat Water in Sarawak with Copper Electrodes

Electrocoagulation is an electrochemical wastewater treatment method, which coagulates impurities particles and ionsby using electrical current. In Sarawak, freshwater peat covers around 1.698 million hectares whereas the other 154,000 hectares are mangrove. Peat water is the water or moisture produced from these peatland or peat soil. Clean water availability in the rural coastal regions are limited due to the high financial cost of distribution of essential clean water resources to sparse population in the remote areas. Therefore, a cost-effective standalone electrocoagulation system for the treatment of peat water in Sarawak is one of the suggested solutions to this water supply problem. The main aim of this research is to develop a continuous electrocoagulation water treatment system by using copper electrodes to treat peat water in Sarawak. The peat water treated is targeted to achieve at least standard quality for domestic usage and the parameters studied to measure the optimal design of the treatment system are the turbidity, total suspended solids (TSS), total organic carbon (TOC), pH and chemical oxygen demand (COD) of the water treated. The experimental results meet the standard for Raw Water Quality and Drinking Water Quality with an optimum parameter of 20 electrodes, 0.7 cm inter electrodes spacing, current density of 5.99A/m2 and treatment time of 100 minutes. The total operating cost for the optimize parameters is RM 0.11 per litre of peat water. Overall, the treatment ofpeat water by using continuous electrocoagulation with copper electrodes is feasible.

Analisa Model Struktur Geologi Untuk Menduga Air Tanah Dengan Menggunakan Metode Geolistrik

Gondanglegi Kulon Village is located in Gondanglegi District, Malang Regency, the research location is in the Muhammadiyah Entrepreneur Islamic Boarding School area. From the results of information from local villagers, it was explained that in the study area there was no shallow groundwater found. This is also reinforced by the fact that there are no wells in the settlements of the residents around the Entrepreneur Muhammadiyah Islamic Boarding School, so that practically no residents use wells to fulfill clean water, they still depend on river water or PDAM services which are relatively expensive and continuous. still below expectations. As a center for religious education, Islamic boarding schools continue to develop supporting facilities. One of the most needed facilities is the availability of clean water. Quantitatively, the supply from the PDAM is not sufficient and the operational costs borne by the manager are too high. The use of groundwater is a solution that can be used to meet the needs of clean water at the research location. Therefore we need a technology to identify the point of exploration, the technology used in this research is geoelectric resistivity. By using the resistivity geoelectric method, it is expected to know the rock structure at the research location and see the potential for deep groundwater. Thus, the hope that in the future the Entrepreneur Muhammadiyah Islamic Boarding School (PPEM) will no longer depend on water raw materials from the PDAM, so the hope is that daily operational costs related to clean water needs can be minimized. From the results of the analysis and discussion, 2 (two) points of drilling recommendations were obtained, but with technical and non-technical considerations, exploration was suggested at point 3 with a potential of 4.2423 L / sec. Where at this location is a rock lithological arrangement consisting of a top soil layer, a clay layer, a tuff layer, a sandy silt layer, a sand layer and a gravel layer.

Identification of the constraints of physical properties on fluid flow rate (as a preliminary study for analysis of changes in subsurface conditions in the KEK Mandalika Lombok)

The KEK Mandalika area, the southern coast of Lombok Island, is an area that is growing up in the tourism sector. The main need for tourist areas is the availability of clean water. The problem that occurs in coastal areas is seawater intrusion. The seawater intrusion can cause the changes in subsurface conditions, especially in groundwater. These changes have an impact on changes in subsurface physical properties, which can be detected by geophysical measurements and modeling based on geoelectric and gravity data. In monitoring the changes of subsurface conditions, it is necessary to observe the constraints based on the value of conductivity, density, viscosity, and fluid flow rate so that physical modeling can be carried out. The method used was an experiment with 11 mixed solutions of groundwater and seawater with different concentrations. The results show that the salinity, conductivity and density have a proportional relationship with viscosity. The higher the viscosity, the lower the groundwater flow rate, and vice versa. Based on these results, the value of the constraints for each variable is obtained, which is conductivity (1.930- 38) mS; density (0.995-1.021) kgm−3 ; salinity (1.06-25.1) ppt; viscosity (0.835-0.876) x10−3 kgm−1s−1 ; fluid flow rate (1292-1388) ms−1 .