Simulation of Rainwater Harvesting Potential to Satisfy Domestic Water Demand Based on Observed Precipitation Data in Jakarta

Jakarta as the most populous urban center of Indonesia has a major problem related to clean water availability for the domestic needs of its residents, who mostly depend on the extraction of groundwater. The rooftop rainwater harvesting (RRWH) system is a solution to reduce the use of groundwater to satisfy domestic water needs. This study used demographic data and precipitation observation data from the rain gauge network in Jakarta to simulate the water supply from rainwater harvesting from 2010 to 2019 in each municipality. Three simulations were carried out to calculate the percentage of domestic water demand (DS) satisfied by RRWH based on the proportion of residential areas installed with RRWH (RA). The results showed that an RA value of 0.2 produced the lowest DS (approximately 11% to 18.7%), while an RA value of 0.3 produced a higher DS (approximately 16.3% to 28%). An RA value of 0.4 resulted in a DS of around 21.8% to 37.4%. Overall, the RRWH system could provide up to 30% of domestic water demand on average, with South Jakarta having the highest fulfillment of water needs with an average of 28% based on the three simulations, while Central Jakarta had the lowest with 16.4%.

Impact of Rapid Tourism Growth on Water Scarcity in Bali, Indonesia

Despite Bali’s dependency on tourism, concerns over the impact of tourism on water scarcity are increasing. The objective of this study is to analyze the clean water demand related to tourism growth and compare them with the available clean water supply. This study suggested that tourism water demand has increased by 20.8 million m3 (295%) from 1988 to 2013. Sixty-eight percent of the increase was concentrated in Badung Regency, where the tourism water demand ratio has increased from 31% to 46%. The study also suggested that rapid population growth has caused an increase in domestic water demand by 48.3 million m3 (48%). This study also shows that the capacity of clean water supply in Bali has increased significantly to meet these demands and the water supply coverage of domestic water demand has increased significantly from 13% in 1988 to 53% in 2013. The water supply coverage of tourism demand varies from year to year with an average of 28% in the study period. The increasing issues over water scarcity despite the improvement in the coverage of domestic water demand suggest further investigations. Yet, despite the large gap between supply and demand in the tourism sector the industry still can have undisrupted clean water throughout the year. This indicates the use of alternative clean water which can be obtained locally such as groundwater. Wise water management through the sharing of scientific data, including in the tourism sector is imperative in solving water scarcity in Bali. Keywords: clean water demand, water scarcity, Badung Regency

Urban stormwater harvesting for domestic water supply: a water evaluation and planning approach

Renewable groundwater and surface water supplies are insufficient for the existing urban population all over the world as water demand is increasing rapidly. Usage per capita in urban areas transcends 160 liters per day. Climate change is projected to increase water demand even more. Sources of surface water obtained by stormwater runoff can be well used to fulfill this requirement. The main objective of this work is to assess the water supply and demand in the dry condition in the Coimbatore region, Tamil Nadu, India, and to use the Water Evaluation and Planning method to create a model for supply and demand in the future. There are more than three dozen of surface water bodies in and around the metropolitan center. Most sources are heavily encroached upon. By linking stormwater runoff from its respective elevation to the accessible surface water bodies, an additional water supply source can be obtained. By using the Water Evaluation and Planning framework as a guide, models were developed to determine potential needs, compare demand and supply, water usage, lack of water use, and population coverage. The enhanced stormwater drainage system for Coimbatore city was also designed in such a way that the corporation's various roads were connected to the major water bodies. The domestic water demand in the future is predicted to be around 27 Million Cubic Feet(MCFT). Meanwhile, the possible amount of stormwater collection in the selected water bodies is predicted to be 50 Million Cubic Meter (MCM) to 320MCM. Thus, the study concluded that 100% of urban domestic water demand can be met if the urban stormwater is utilized by harvesting and storing in surface water bodies.

Assessment of Urban Domestic Water Demand and Supply in Edo North, Nigeria

An exponential increase in the global population has seriously put pressure on land and water resources. It is projected that 33% of the worldwide people will be highly water-stressed by the 2050s if effective strategies are not developed. The study assessed urban domestic water demand and supply in Edo North senatorial district in Edo State, Nigeria. This is with the view of exploring some critical water resource variables to determine water security, distribution, and accessibility of safe drinking water in Edo North in Edo State in Nigeria. Integrated Water Resource Management Tools (IWRT) such as Water Poverty Index (WPI) and Water Accessibility Indicator (WAI) was applied. The results show that Auchi is highly water-stressed at the Estako-west area with MPI and WAI values of 0.24 and 0.33. Conversely, Okpella and Agenebode in Eskako central have MPI and WAI values 0.34 and 0.31, and 0.31 and 0.32. Sabo Gida Ora and Isobe in Owan East and West have better safe drinking water coverage and accessibility with the indicator values of 0.54, 0.53 [WPI], and 0.61 and 0.59 [WAI]. It is generally observed that the supply of potable water in the Edo North is highly unsecured and unsustainable to meet the current and future demand. Valuable and economic time is wasted to gather water from an average closest distance of 1.3 km from home to some designated water taps. In conclusion, it is imperative to design a robust integrated water policy that should include Private-Public-Partnership (PPP) to invest in the provision of safe drinking water.

Assessment of Urban Domestic Water Demand and Supply in Edo North, Nigeria

An exponential increase in the global population has seriously put pressure on land and water resources. It is projected that 33% of the worldwide people will be highly water-stressed by the 2050s if effective strategies are not developed. The study assessed urban domestic water demand and supply in Edo North senatorial district in Edo State, Nigeria. This is with the view of exploring some critical water resource variables to determine water security, distribution, and accessibility of safe drinking water in Edo North in Edo State in Nigeria. Integrated Water Resource Management Tools (IWRT) such as Water Poverty Index (WPI) and Water Accessibility Indicator (WAI) was applied. The results show that Auchi is highly water-stressed at the Estako-west area with MPI and WAI values of 0.24 and 0.33. Conversely, Okpella and Agenebode in Eskako central have MPI and WAI values 0.34 and 0.31, and 0.31 and 0.32. Sabo Gida Ora and Isobe in Owan East and West have better safe drinking water coverage and accessibility with the indicator values of 0.54, 0.53 [WPI], and 0.61 and 0.59 [WAI]. It is generally observed that the supply of potable water in the Edo North is highly unsecured and unsustainable to meet the current and future demand. Valuable and economic time is wasted to gather water from an average closest distance of 1.3 km from home to some designated water taps. In conclusion, it is imperative to design a robust integrated water policy that should include Private-Public-Partnership (PPP) to invest in the provision of safe drinking water.

Estimating Gridded Domestic Water Demand and Assessing its Vulnerability over South-East Asian Countries

<p>During the past three decades, the over-growing population of the south-east Asian countries is becoming a threat to the available potential water sources. This region also includes many developed as well as developing countries including Korea, China, Japan and India, and the higher rate of GDP growth also enhanced the living standard of people. As a result, the water scarcity has been increasing in various mega-cities of the region. Here, we present the assessment of grid-scale domestic water demand of each country by evaluating the gridded Domestic Structural Water Intensity (DSWI) over a period of 1995-2015 at a spatial resolution of 0.5°. We estimated yearly grid-scale DSWI with using the past economic development based on GDP and the population. Considering the gridded water demand, we assessed the vulnerability of major river basins of the region and the few cities having more than one million population. A few mega-cities in India located in arid and semi-arid regions of the river basins are already experiencing water stress. Developing such gridded dataset will give a better shape to project the future water demand by integrating the datasets within a water demand module of any land surface models.</p><p><strong>Acknowledgements</strong></p><p>This work was supported by a grant from the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2020R1A2C2007670).</p>

A Panel Data Estimation of Domestic Water Demand with IRT Tariff Structure: The Case of the City of Valencia (Spain)

In urban water provisioning, prices can improve efficiency, contributing to the achievement of the environmental objective. However, household responses to price changes differ widely based on the household characteristics. Analyses performed at the aggregate level ignore the implications of water demand incentives at the individual household level. A large data sample at the household level enables estimation of econometric models of water demand, capturing the heterogeneity in domestic consumption. This study estimated the domestic water demand in the city of Valencia and its elasticity, along with the demands of its different districts and neighbourhoods (intra-urban scale analysis). Water price structure in Valencia is completely different from that of other Spanish cities: it is a price structure of increasing volume (increasing rate tariffs, IRT). For this estimation, from a microdata panel at the household level, the demand function with average prices for the period 2008–2011 was estimated using panel data techniques including a fixed effect for each neighbourhood. The domestic water demand elasticity at the average price in Valencia was estimated at −0.88 (which is higher than that estimated for other Spanish cities). This value indicates an inelastic demand at the average price of the previous period, which can cause consumers to overestimate the price and react more strongly to changes.