Developing a City Water Balance Plan

Introduction


In the last century, global water use has increased by more than twice the rise in population creating great pressure on the water reserves in many regions. In particular, urban water management is facing a variety of serious challenges. Population growth, rapid urbanization, industrialization, etc. have resulted in the depletion of water resources and increasing pollution. Climate change is adding to these challenges. The water situation in India is alarming. A large number of people, particularly in urban areas, are unable to access safe water.


Challenges in Urban India


According to a recent report of the NITI Aayog (Composite Water Resource Management, 2020), India is facing a grave water crisis - nearly 600 million people are facing high to extreme water stress. The report has listed twenty-one cities like Bengaluru, Chennai, Delhi, Hyderabad, etc. which are running out of groundwater affecting more than 100 million people. If the current state of affairs is allowed to continue the country will lose 6 percent of its GDP by 2050 by when fifty percent of the population is expected to live in urban areas thereby impacting a great many people.


To address the precarious urban water situation, the Ministry of Housing and Urban Affairs (MOHUA) has recently launched the Jal Jeevan Mission (Urban) to provide universal coverage of water supply to all through functional taps in all the 4378 towns in accordance with the SDG Goal- 6. In order to promote the circular economy of water, the JJM (U) has mandated the preparation of a city water balance plan for each city that focuses on recycling and/or reuse of treated wastewater, rejuvenation of water bodies, and the practice of water conservation.


Most of the cities lack an effective water management system and are unable to meet the increasing water demand of the population. Whatever little water is extracted and provided through the formal system, a significant portion of it is lost. According to the National Sample Survey, a very high percentage (about 40 to 50 percent) of water is reportedly lost in the distribution system due to various reasons. The situation is further exacerbated by changing climate conditions. To fulfill the objective of JJM(U) and to secure the future of our cities it is necessary to understand and assess the water situation in our cities from a natural and urban perspective and accordingly prepare a City Water Balance Plan (CWBP) that helps to develop water resilient cities. This is also mandated by the JJM (U).


Objective


To address the precarious urban water situation, the Ministry of Housing and Urban Affairs (MOHUA) has recently launched the Jal Jeevan Mission (Urban) to provide universal coverage of water supply in all the cities of India. The JJM (U) mandates the preparation of a city water balance plan for each city. However, this is a new thing for the Indian cities which has hitherto not been attempted. There is hardly any city that has developed a comprehensive Water Balance Plan and used it to plan and manage its water resources in a resilient manner.


The article expands on the aim of the Jal Jeevan Mission (Urban) particularly on the City Water Balance Plan (point 3: JJM(U) to promote the circular economy of water through the development of a city water balance plan for each city focusing on recycling/reuse of treated sewage, rejuvenation of water bodies and water conservation), explains the concept of the City Water Balance Plan, describes the typical components of the Plan and discusses the benefits or usefulness of preparing and using such as a Plan.


Water Balance Plan


A water balance plan is a comprehensive way to understand the flow of water in and out of our urban or rural systems thus giving us a balance of water that is retained in the ecological system of the habitat. Water balance plan derives its meaning from the term water balance, which is equated as:


Changes in storage = Total inflow – Total outflow


Water inputs are usually brought by precipitation. Outputs are from the combination of evaporation and the transpiration of plants, called evapotranspiration. Therefore,


Changes in Storage = (Precipitation + Soil Moisture) - (Runoff + Evapotranspiration)

Picture 1: Water Balance

A Water Balance Plan is a comprehensive way to understand the flow of water in and out of our urban systems thus giving us a balance of water that is retained in the ecological system of the urban habitat. Water balance planning does away with the traditional linear system of extract-use-dispose of the system instead, it emphasizes the circular economy of water. Essentially, the water balance plan is a circular model which is based on three principles:

  • Keep production systems and materials in sustainable use,

  • Design out waste and pollution, and

  • Regenerate the natural systems through reuse and conservation.

An important aspect of the study of the water balance plan is its expanse - covering a wide range of existing metrics and datasets. It involves understanding and assessing the current and future pressures on water services, its demand assessments, the ecosystem, and precious natural capital to meet the resource needs, increasing population growth, climate change, etc. To that extent, it is important to undertake the water balance plan as a Landscape Assessment. The landscape scale is a useful unit for holistically managing various uses and stakeholder needs within a given region. The landscape or integrated approach simultaneously addresses multiple objectives by seeking synergies and minimizing trade-offs. The article uses this landscape assessment system and has incorporated multiple factors that contribute to the development of a comprehensive water balance plan.


Developing the City Water Balance Plan as a Landscape Assessment


The first step in developing the City Water Balance requires the assessment of the freshwater resources, accomplished through the quantification of the components of the hydrological cycle. As already indicated, the (natural) hydrological balance equation is based on the principles of conservation of mass in a closed system: any change in the water content of a given soil volume during a specified period must equal the difference between the amount of water added to the soil volume and the amount of water withdrawn from it.


Identifying the study limit


While preparing the City Water Balance Plan, it is very important to identify the extent or boundaries of the study or assessment and its limitations – will it be limited to the core urban areas, the municipal area that is enclosed within the municipal boundaries, or the urban metropolitan area or otherwise? Delineating the boundary of the study is critical since it has a bearing on several factors – from the scope of the study to its management, the assignment period, and the logistics involved. Since water is seldom confined in one place, and its estimation, yield, and potential typically occur across a large or extended region, it is important to carefully decide and identify whether and how the water basin or sub-basin is to be included to assess the water situation covering features such as type of soil, estimation of yield, groundwater potential, regeneration, etc.


Land Use/Land Cover


A detailed study of the urban area, demographics or population, growth over the years, socio-economic and geographical features, the urbanization pattern over time, etc. are important and necessary for developing the Water Balance Plan. Annual land use over several years (at least last five years), conversion of land use, change from barren and/or agricultural land to urban and the rate of increase in urbanization in the past, loss of water bodies or transformation from permanent waterways into ephemeral streams, decreasing trend or loss of groundwater, etc. should be assessed and calculated for the study. This will indicate the kind of pressure that exists on the natural resources (water) and can indicate the kind of mitigation measures required.

A land use/land cover (LU/LC) study is needed particularly to assess the changes over a given time span in order to have a proper understanding of the planning and utilization of natural resources and their management. Traditional methods of gathering demographic data, census, and analysis of environmental samples must be substantiated with satellite remote sensing and Geographical Information Systems since traditional systems may not be adequate for multicomplex environmental studies. Secondly, promotion of strategic planning of green or open spaces, restricted use of concretized or hard ground cover rather having soft grounds can enable water percolation and recharge. Also, it can reduce heavy stormwater run-off, thus securing a better future in the current or future urbanization trend. Of course, these will need to be adequately reflected in the city’s land-use planning and building bylaws.

Picture 2: Land Use/Land Cover Maps

Topography, Physiography, Geology, and Hydrogeology


Developing the Water Balance Plan will require studying the main topographical and physiographical features of the basin/sub-basin, the different geological formations occurring in the basin / sub-basin, lithology, the hydro-geological formations of the basin/sub-basin including the surface and groundwater availability with certain detail of water-bearing formations. Such information is usually available with the Central Ground Water Board and they may be tapped early during the study period.

It is also important to collect data on the Slope, Aspect, Hill-shade, and Curvature layers. Slope defines the change of elevation in a particular area that influences the runoff. Generally, in gentle slopes, the movement of water is slow, which allows more percolation into the ground. On the other hand, the steep slope increases the rate of runoff. Hill-shade denotes the brightness of a given area. It is an important factor particularly for cities located in the Himalayan region. These are important inputs into the Water Balance Plan. The Aspect of a region identifies the steepest slope in the down direction. It can be thought of as the direction of the slope. Developing the Aspect map is an important parameter to understand the impact of the sun on the local climate of the area. Also, the Aspect may have a strong temperature effect. This is because of the angle of the sun in the northern and southern hemispheres which is less than 90 degrees or directly overhead. Together with temperature, sunshine, and hill-shade data, it provides important information on ground moisture, surface temperature, plant communities, etc.


Soil and Land Use


Information regarding soil data including the type of soils and their properties namely color, depth, chemical characteristics, PH value, texture, structure, drainages, etc. will be most helpful. A map showing the different types of soils in the basin/sub-basin with the description of land irrigability classification based on the physio-chemical characteristics of the soils should be very helpful. This information or data may be available with the Irrigation Department or may have to be generated through soil surveys.


Aquifer Management Plan


By extracting water features individually from the multi-date satellite images, surface water change can be usually detected and the loss or change quantified thereby providing an indication of the potential of this water resource for the future period.


Another important aspect of the Water Balance Plan is the aquifer or groundwater mapping.

The mapping is designed to take a significant step forward in groundwater resource management by identifying and mapping the aquifers, quantifying the available groundwater resources potential, and proposing plans appropriate to the scale of the demand, aquifer characteristics, and the institutional arrangements for its management. Geological mapping in the country was initially carried out by the Geological Survey of India. Also, systematic groundwater surveys were undertaken by the Geological Survey of India and by the Central Ground Water Board. It would be worthwhile to tap into these institutions for getting the required information.

Picture 3: Groundwater Condition, India

By preparing the groundwater levels or aquifer management maps based on time series, the decrease in the water level can be discerned for the different seasons. Thus the overall decreasing trend of groundwater that may be witnessed in the city may be assessed and attributed to the change in topography, the soil characteristic, land use and/or the urbanization pattern in the region, or a combination of such factors. If adequate resources are available, the creation of a micro-level aquifer information system may be taken up as part of the Water Balance Plan. This will greatly facilitate the formulation of a detailed aquifer management plan with sufficient details at a granular level, i.e., at optimal size in accordance with the nature of the aquifer, the stress on the resource and prevailing water quality, and the potential mitigation measures developed. Aquifer mapping to be prepared must be supported by an aquifer information system created with minimal field data collection. Sub-surface water inflows and outflows information is necessary to have an in-depth understanding of the aquifers. However, this may be undertaken in a separate scope of study since it requires rigorous geological studies over a longer period of time for which specialized equipment is required.

Picture 4: Map of major Aquifer Systems in India

Climate, Rainfall, Temperature, and Sunshine


The increasing adverse effect of human actions on the climate system is increasing and climate-induced changes are becoming intense as well as widespread in their impacts on humans, their habitats, and the natural systems, therefore, on the availability of water. Rainfall data including maximum, minimum, and normal rainfall for the maximum period of availability must be documented. This can be obtained from existing rain-gauge stations, the state government, or from the IMD. Isohyet mapping of average annual rainfall for a time period can be thus prepared. This will help in estimating the average rainfall across a particular city or area. The maximum and minimum range of monthly sunshine hours in percent as observed at the IMD observatories in or nearest to the city may be also collected. Together with Hill-shade and Aspect, it will allow a detailed assessment of the water retention, runoff, or transpiration potentials.

Picture 5: Example of a simple Isohyet Map

Evapotranspiration


Evaporation is the process whereby water is converted to vapor and removed from the evaporating surface. Water evaporates from a variety of surfaces, such as lakes, rivers, pavements, soils, and wet vegetation. Transpiration consists of the vaporization of water contained in plant tissues and the vapor’s removal to the atmosphere. Crops predominately lose their water through stomata. These are small openings on the plant leaf through which gases and water vapor pass. Evapotranspiration (ET) is influenced by the physical characteristics of water, land or soil characteristics, and season or time in the year. Sunshine, wind speed, density, vegetative cover, cloud cover, and soil moisture also influence ET. Plotting of Evapotranspiration over a time period, say 20 years will indicate its trend. The trend is important to consider since an increase in evapotranspiration can result in a decrease in surface runoff, which can create further stress on water demand. On the other hand, lower trends may signify heavy urbanization and reduced vegetative cover thereby indicating significant surface runoffs. All these have implications for developing and managing a water resilience plan.

Picture 6: Evapotranspiration Map

Equitable Access to Water

Our cities and towns are engines of growth, yet the inadequate provision of sanitation and clean water still persists across the population and the urban poor find it difficult to have access to safe water both quantity and quality-wise. Our unplanned urban areas have huge consequences for public health and the country’s development prospects as recently and rudely demonstrated by the Covid19 pandemic. The occurrence of the Covid19 pandemic has once again brought out the stark inequalities in water flow, quality of water supplied and the frequent unavailability of water in most slums. Increasing water shortages, intermittency of water supply, poor infrastructural networks to provide quality drinking water, and the spatial splintering that characterizes many low-income neighborhoods present a challenge towards suppressing the spread of COVID19. This question is even tougher for the marginalized populations who do not only receive erratic water supply but meet their daily water needs through a dynamic patchwork of sources including tankers, standpipes, and sachet or packaged water.

In addition, in many thriving towns and cities, the poor inhabitants are residing directly in the paths of riverine or coastal flooding or sea rise due to climate change. The development of any City Water Balance Plan must therefore include the demands of the less privileged of the society and should as a priority attempt to ensure an equitable distribution of the water resources to the disadvantaged populace through improved access to the services. This is very much in line with the United Nations’ mandate for the Sustainable Development Goals in 2015 with the eradication of water-related poverty and induced vulnerability as one of its targets, i.e., Goal 6 pertaining to the achievement of universal access to safe drinking water, hygiene, and sanitation by the year 2030. Moreover, this is also the mandate of India’s flagship mission such as the Swachh Bharat Mission 2.0 and the Pey Jal Mission. Achievement of this goal is also crucial for the cities for moving up considerably on the swachh survekshan or clean India improvement scale.

Urban Water Management System

A city may depend on either or both surface and sub-surface water (groundwater) to meet its potable water demand. The existing surface systems including total water withdrawal from each surface water resource and its share in the totality with the total contribution or withdrawal from the sum of all surface water resources need to be calculated. The type, condition, functional efficiency, etc. for each withdrawal system must be documented. Likewise, water demand projections should be made for the defined period for the water balance plan and the gap overtime must be estimated.

Similarly, for sub-surface or groundwater sources, all the extraction points, their distribution across the urban area, and the total withdrawal should be meticulously documented. India is the largest consumer of groundwater in the world. Averaged for 71 cities and towns, groundwater constitutes 48 percent of the share in urban water supply while 56 percent of metropolitan, class-I, and class-II cities are dependent on groundwater either fully or partially (NIUA, 2005). Unaccounted water in urban areas exceeds 50 percent according to the CGWB’s report on the groundwater scenario in 28 Indian cities (CGWB, 2011). Groundwater supply in each of the city’s districts or divisions must be calculated based on the pumping hour, the discharge value of each pump, total withdrawal from pumps amounts, etc., and compared to the demand. It would be worthwhile to find out wherefrom the highest and lowest extractions happen and the prevailing conditions in those areas. Details of import from existing, ongoing, and future identified projects located outside the city or the basin/sub-basin should be collected from State Govt. sources and duly considered for future demand projections. Similarly, details of export, outside basin/sub-basin from existing, ongoing, and proposed projects located within the basin/sub-basin shall also be collected from State Govt. and briefly described in the study.

Demand, Supply and Reuse

Water demand between different users - domestic, institutional, commercial establishments as well as for irrigation will need to be calculated. Usually, domestic water needs of the city may claim the highest percentage of use, while industrial or commercial demand may be of lower percent. Commercial and industrial users in several cities are offered bulk supplies. In some cities, private or group housing estates are also offered bulk supplies. All types of supplies need to be included in the study. Total water demand across the seasons and annual demand may be calculated and projected over a period of 10 or more years to identify the exact demand as well as the varying nature of the demand. Similarly, the total water supplied may be calculated from the water extracted from the surface and from the ground, the hours of supply, and adjusted against the distribution loss. It would be a good idea to undertake a random check on the quantity of water actually reaching the end-users to discern the supply situation. Water supply infrastructure including sumps, water treatment plants, OHT and CWR for storage as well as the extent of piped water distribution network with functional household tap connections have to be documented and analyzed to discern the gap between demand and supply and to identify other issues. Water conservation measures including rainwater harvesting and/or recharging of the groundwater, revitalizing and conserving existing waterbodies can be useful mitigative measures to address water stress and can be easily managed and operated by communities and institutions.

Alongside the demand and supply calculations for potable water, it is also important to assess the wastewater situation in the city. The number of Sewage Treatment Plants (STPs) or Faecal Sludge Treatment Plants (FSTPs), their distribution in respect to the population, their current treatment capacity, and the future provisions with respect to the increasing urban population and rate of urbanization needs to be assessed. Importantly, the present volume of wastewater generated, the amount collected and treated have to be documented and scenario building for the future has to be worked out where several alternative mitigation measures such as having on-site sanitary systems coupled with effective FSTPs and/or decentralized wastewater treatment along with phytoremediation, cluster septic tanks, etc. can be thought of which increasingly allows for recycling and reusing wastewater in secondary usages like irrigation and flushing.

Benefits of Developing a City Water Balance Plan

What are the benefits that we can get from applying water balances to our cities? By applying a water balance we get to better understand whether our city's water resources are “at quantitative risk” - or not and "the gap to good status" that needs to be filled with various measures. Water balance plans support the identification of drought and water scarcity situations. It contributes to the development of common country-wide knowledge with coherent and comparable data, harmonized definitions, and a common understanding of the relevant assessments when applying water balances within the proposed framework of the Jal Jeevan Mission (and by using this article as guidance). The city managers will have a good overview of the spatial and temporal variability of water resources, under current and future (scenario building) conditions in order to design, identify or bridge the gaps of appropriate allocation schemas. With a City Water Balance Plan in hand, the city managers can have a robust base for additional water resources assessment and management at various scales: runoff estimation, groundwater recharge potential, nitrates mass balance, water-energy nexus, etc. They will be able to identify “where best to target efforts” (be it identifying areas where the action is needed due to existing or future water stress, reducing abstraction from a given use, focusing on runoff, increase storage, develop reuse, etc.) when selecting measures for improving the quantitative state of water resources, therefore, prioritize actions as a short-, medium- and long-term action. Water Balance Plans provide a common platform for building a “shared understanding” of issues between stakeholders and different water users, as all are represented by one or more components of the water balance. An important contribution of a Water Balance Plan is to provide a coherent framework for combining and structuring hydrological, socio-economic, and climate information which is traditionally straight-jacketed in different compartments and seldom brought together for the common understanding of the various departments, operators and stakeholders involved or engaged in building a water resilient city.

The availability of adequate water is critical to sustain life and to generate economic activities in any area. However, the amount of water available and the amount of water needed is often off-balance. Crucial and stage-wise planning and deficient development initiatives with the right understanding of the regional conditions are always essential while studying and recommending implementation suggestions to the local governing bodies related to Water services.

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