Available via license: CC BY 4.0
Content may be subject to copyright.
Citation: Dutta, J.; Choudhury, R.;
Nath, B. Quantification of Urban
Groundwater Recharge: A Case Study
of Rapidly Urbanizing Guwahati City,
India. Urban Sci. 2024,8, 187. https://
doi.org/10.3390/urbansci8040187
Academic Editor: Luis
Hernández-Callejo
Received: 25 July 2024
Revised: 10 October 2024
Accepted: 21 October 2024
Published: 24 October 2024
Copyright: © 2024 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Quantification of Urban Groundwater Recharge: A Case Study of
Rapidly Urbanizing Guwahati City, India
Jayashri Dutta 1, Runti Choudhury 1, * and Bibhash Nath 2, *
1Department of Geological Sciences, Gauhati University, Guwahati 781014, Assam, India
2Department of Geography and Environmental Science, Hunter College of the City University of New York,
New York, NY 10021, USA
*Correspondence: runti@gauhati.ac.in (R.C.); bibhash12@gmail.com (B.N.)
Abstract: The interaction between groundwater and urban environments is a growing concern for
many rapidly urbanizing cities around the world, affecting both recharge and flow, since impervious
surfaces reduce infiltration by increasing runoff, whereas over-abstraction leads to groundwater
depletion and land subsidence. Additionally, industrial pollution and wastewater disposal contribute
to contamination, impacting groundwater quality. The effective governance of groundwater within
such urban locales necessitates a profound understanding of the hydrogeological context, coupled
with robust tools for projecting fluctuations in groundwater levels and changes in water quality
over time. We quantified urban groundwater recharge in Guwahati city, Assam, India, using the
rainfall infiltration method and a numerical approach. Precipitation, evapotranspiration, runoff,
and recharge from surface water bodies were considered the components of natural recharge, while
leakages from water supply, domestic wastewater, and industrial wastewater were considered the
components of urban recharge. The cumulative total of natural and urban components determines
the actual groundwater recharge. The estimated natural groundwater recharge is 11.1 MCM/yr,
whereas the urban groundwater recharge is 44.74 MCM/yr. Leakages from urban infrastructure
resulted in significantly higher groundwater recharge than from natural inputs. Steady declines in
groundwater recharge were observed from estimates taken at various time points over the past two
decades, suggesting the need for prompt action to improve groundwater sustainability.
Keywords: groundwater; recharge; water supply; wastewater leakage; Guwahati city
1. Introduction
Groundwater is considered one of the most valuable and accessible freshwater re-
sources for consumption around the world [
1
]. It contributes to the social and economic
development of nations through proper planning and good governance [
2
]. Groundwa-
ter is preferred over surface water because it is reliable and free from any pathogens.
However, unplanned urbanization and population growth have led to the vulnerabil-
ity of groundwater resources, thus impacting sustainable development [
3
]. Because the
demand for water increases with urbanization and population growth, it results in the
over-abstraction of groundwater. In addition, urbanization alters hydrological cycles and
groundwater recharge processes [
4
] and increases runoff and peak flows in rivers [
5
]. Over
the past decade, there has been an increase in research investigating the complex changes
in hydrological cycles and urban groundwater recharge processes, expedited by increased
population and urbanization [6,7].
Groundwater recharge in urban areas follows a complex pattern. Urbanization in-
creases impervious surfaces, thereby decreasing the infiltration process and increasing
surface runoff [
8
]. The expansion of urban areas causes significant changes in the urban
surface runoff index and urban percolation index [9]. Urbanization can increase the inten-
sity and frequency of flooding [
10
]. Therefore, groundwater management in an urban area
Urban Sci. 2024,8, 187. https://doi.org/10.3390/urbansci8040187 https://www.mdpi.com/journal/urbansci
Urban Sci. 2024,8, 187 2 of 11
requires a thorough understanding of the aquifer system and the interactions between soil
and groundwater systems. The evaluation of the hydrogeochemical quality and quantity
of an aquifer system serves as a tool for managing groundwater. The accurate computation
of recharge is useful for the management and conversion of this valuable resource [
11
]. Be-
cause of the large spatial and temporal variability in recharge rates, groundwater recharge
estimation in urban areas is rather difficult [
12
]. Although it was previously believed that
groundwater recharge decreases with increasing urbanization, it has now been proven
otherwise [13,14].
In an urbanizing city, recharge occurs through natural processes along with some
urban components, which also contribute to groundwater recharge [
15
]. Urban popula-
tions, industries, and commercial areas have been provided with adequate water based on
demand. Urban aquifers can be impacted by leakages from water supply mains, sewerage
networks, septic tanks, and soakways. Such leakages can contribute significantly to ground-
water recharge [
6
,
16
]. As direct measurements of urban groundwater recharge are difficult,
large-scale indirect approaches are often used to estimate groundwater budgets [
17
]. Meth-
ods for estimating urban groundwater recharge include using empirical and conceptual
water balances, applying chemical or isotopic tracers, time series analyses, and statistical
and numerical modeling [
18
–
20
]. A commonly used method for the estimation of urban
recharge is the water balance approach [
7
]. Using this method, many hydrogeologists
have estimated urban groundwater recharge and found a large volume of groundwater
recharged through urban components [19–21].
In India, many states face acute drinking water shortages, leading to the implemen-
tation of regulatory measures by the Central Ground Water Authority (CGWA) to reduce
groundwater exploitation [
22
]. A significant decline in per capita water availability was
reported, from 5177 m
3
in 1951 to 1545 m
3
in 2011, and is projected to decrease further
to 1140 m
3
in 2050 [
23
]. Such changes in per capita water availability contribute to signif-
icant stress on groundwater aquifers, leading to a decline in water levels and increased
contamination. Wakode et al. (2018) [
7
] observed that groundwater recharge through
urban components outweighed natural processes in the city of Hyderabad. Using a model-
based estimation, Tomer et al. (2021) [
24
] observed greater contributions of anthropogenic
recharge than natural recharge to the overall groundwater budget in Bengaluru, India.
Awasthi et al. (2022) [
25
] observed an association between urbanization, groundwater stress,
and land deformation by analyzing time-series satellite imagery. Therefore, detailed knowl-
edge of groundwater recharge is essential for sustainable water resource management,
particularly in urban areas where groundwater resources are under stress [12].
The objective of this study is to quantify groundwater recharge in the rapidly ur-
banizing Guwahati city, India. We assume that groundwater recharge occurs through
both natural and urban components. Given the complexity of urban areas, we used a
combination of the rainfall infiltration method and a simple numerical approach to estimate
contributions from both natural and urban recharge components. Rainfall, evapotranspi-
ration, runoff, and surface water bodies were considered natural recharge components,
while leakages from the water supply, domestic wastewater, and industrial wastewater
were considered urban recharge components.
2. Study Area
The study area, Guwahati city, is located between 26
◦
00
′
N and 26
◦
15
′
N latitude and
91
◦
30
′
E and 91
◦
55
′
E longitude (Figure 1). The study area has an estimated population
of 1,176,000 spread across the north and south banks of the Brahmaputra River, covering
an area of 328 sq. km [
26
]. The major surface water bodies that contribute to recharge
include Deepor Beel, Sarusola Beel, Borsola Beel, Silsako Beel, and Dighali Pukhuri [
27
].
The geomorphology of the study area includes alluvial plains and residual hills. Residual
hills are composed of granite–gneissic complexes.
Urban Sci. 2024,8, 187 3 of 11
Urban Sci. 2024, 8, x FOR PEER REVIEW 3 of 11
Figure 1. Map showing the extent of the study area, Guwahati city, Assam, India. The inset map
shows the state of Assam, India, with the study area highlighted in red.
The Guwahati Municipal Commiee (GMC), Guwahati Jal Board (GJB), Jawaharlal
Nehru National Urban Renewal Mission (JNNURM), and Japan International Coopera-
tion Agency (JICA) together supply 66.5 million liters per day (MLD) of water, serving
42.61% of the city population (Table 1). The remainder of the population relies on ground-
water to meet their demand [26]. The study area has no sewerage networks or sewage
treatment plants (STPs). Therefore, the wastewater produced within the study area is dis-
posed of into open drains. Although some industries own effluent treatment plants
(ETPs), others directly discharge the effluents into open drainage channels.
Table 1. Total water supply in Guwahati city for the year 2022.
Agency Total Water Supply (MLD)
GMC 45
Guwahati Jal Board 9.5
JNNURM 2
JICA 10
Total 66.5
Note: MLD—million liter per day.
3. Materials and Methods
3.1. Assessments of Natural Groundwater Recharge
Groundwater recharge was calculated for both natural sources and inputs from ur-
ban infrastructure. Among natural groundwater recharge sources, surface water bodies,
in addition to precipitation, also contribute significantly to infiltration. Evapotranspiration
and runoff play a crucial role in reducing infiltration. Recharge from precipitation is cal-
culated by subtracting evapotranspiration and runoff from rainfall. However, the rainfall
available for recharge cannot fully infiltrate because impervious surfaces and subsurface
lithology affect its pathway.
The study area is defined by two prominent geomorphic units, i.e., residual hills and
alluvial plains, which are associated with different geological formations (Figure 2a). The
residual hills represent the Proterozoic, while the alluvial plains correspond to the
Figure 1. Map showing the extent of the study area, Guwahati city, Assam, India. The inset map
shows the state of Assam, India, with the study area highlighted in red.
The Guwahati Municipal Committee (GMC), Guwahati Jal Board (GJB), Jawaharlal
Nehru National Urban Renewal Mission (JNNURM), and Japan International Cooperation
Agency (JICA) together supply 66.5 million liters per day (MLD) of water, serving 42.61%
of the city population (Table 1). The remainder of the population relies on groundwater to
meet their demand [
26
]. The study area has no sewerage networks or sewage treatment
plants (STPs). Therefore, the wastewater produced within the study area is disposed of
into open drains. Although some industries own effluent treatment plants (ETPs), others
directly discharge the effluents into open drainage channels.
Table 1. Total water supply in Guwahati city for the year 2022.
Agency Total Water Supply (MLD)
GMC 45
Guwahati Jal Board 9.5
JNNURM 2
JICA 10
Total 66.5
Note: MLD—million liter per day.
3. Materials and Methods
3.1. Assessments of Natural Groundwater Recharge
Groundwater recharge was calculated for both natural sources and inputs from urban
infrastructure. Among natural groundwater recharge sources, surface water bodies, in
addition to precipitation, also contribute significantly to infiltration. Evapotranspiration
and runoff play a crucial role in reducing infiltration. Recharge from precipitation is
calculated by subtracting evapotranspiration and runoff from rainfall. However, the rainfall
available for recharge cannot fully infiltrate because impervious surfaces and subsurface
lithology affect its pathway.
The study area is defined by two prominent geomorphic units, i.e., residual hills and
alluvial plains, which are associated with different geological formations (Figure 2a). The
residual hills represent the Proterozoic, while the alluvial plains correspond to the Quater-
nary. To assess the relationship between these geomorphic features and urban development
Urban Sci. 2024,8, 187 4 of 11
effectively, land use and land cover (LULC) data were also employed (Figure 2b). These
data were instrumental in identifying the extent of built-up areas that have emerged from
the residual hills, providing a clearer understanding of how much area is available for
direct infiltration.
Urban Sci. 2024, 8, x FOR PEER REVIEW 4 of 11
Quaternary. To assess the relationship between these geomorphic features and urban de-
velopment effectively, land use and land cover (LULC) data were also employed (Figure
2b). These data were instrumental in identifying the extent of built-up areas that have
emerged from the residual hills, providing a clearer understanding of how much area is
available for direct infiltration.
Figure 2. (a) Geology and (b) land use and land cover (LULC) map of the study area.
Evapotranspiration and runoff were derived from Climate Engine, a free web plat-
form powered by Google Earth Engine using Terra Climate data [28]. The rainfall data
were collected from the Indian Meteorological Department (IMD) (Table 2).
Table 2. Overview of monthly rainfall, evapotranspiration, and runoff for 2022.
Month Rainfall (mm) Evapotranspiration (mm) Runoff (mm)
January 31.6 36.72 1.11
February 50.4 50.11 2.27
March 5.3 25.25 1.0
April 103.4 108.65 9.45
May 293.4 125.31 55.39
June 499.8 92.47 109.51
July 168.8 136.84 44.89
August 152.8 121.22 4.98
September 81.4 115.07 10.55
October 155.6 101.6 8.62
November 0.0 51.35 0.0
December 0.0 31.73 0.0
Total 1542.5 996.3 247.8
Source: IMD, India and Climate Engine [28].
The rainfall available for recharge was calculated using Equation (1)
R
AVL
= Rainfall − Evapotranspiration − Runoff (1)
where R
AVL
is the rainfall available for recharge.
The volume of recharge from rainfall was calculated using Equation (2)
R
R
= R
AVL
× rainfall infiltration factor × area available for recharge (2)
where R
R
is the recharge from rainfall. The rainfall infiltration factor is the effectiveness of
a formation to infiltrate water [29]. The area available for recharge was calculated for two
geomorphology types using ArcGIS 10.7.1 (Table 3).
Figure 2. (a) Geology and (b) land use and land cover (LULC) map of the study area.
Evapotranspiration and runoff were derived from Climate Engine, a free web platform
powered by Google Earth Engine using Terra Climate data [
28
]. The rainfall data were
collected from the Indian Meteorological Department (IMD) (Table 2).
Table 2. Overview of monthly rainfall, evapotranspiration, and runoff for 2022.
Month Rainfall (mm)
Evapotranspiration (mm)
Runoff (mm)
January 31.6 36.72 1.11
February 50.4 50.11 2.27
March 5.3 25.25 1.0
April 103.4 108.65 9.45
May 293.4 125.31 55.39
June 499.8 92.47 109.51
July 168.8 136.84 44.89
August 152.8 121.22 4.98
September 81.4 115.07 10.55
October 155.6 101.6 8.62
November 0.0 51.35 0.0
December 0.0 31.73 0.0
Total 1542.5 996.3 247.8
Source: IMD, India and Climate Engine [28].
The rainfall available for recharge was calculated using Equation (1)
RAVL = Rainfall −Evapotranspiration −Runoff (1)
where RAVL is the rainfall available for recharge.
The volume of recharge from rainfall was calculated using Equation (2)
RR= RAVL×rainfall infiltration factor ×area available for recharge (2)
where R
R
is the recharge from rainfall. The rainfall infiltration factor is the effectiveness of
a formation to infiltrate water [
29
]. The area available for recharge was calculated for two
geomorphology types using ArcGIS 10.7.1 (Table 3).
Urban Sci. 2024,8, 187 5 of 11
Table 3. Geomorphic units and associated parameters used to calculate rainfall-induced natural
groundwater recharge.
Geomorphic
Unit
Area
(km2)
Paved Area
(km2)
Area Available for
Recharge (km2)
Rainfall Available
for Recharge (mm)
Rainfall
Infiltration Factor *
Total Recharge
(MCM/yr)
Alluvial
plains 254.56 155.9 98.66 298.4 0.22 6.47
Residual hills 73.44 27.1 46.34 298.4 0.11 1.52
Total 328 183 145 7.99
Note: MCM/yr—million cubic meters per year; * rainfall infiltration factor [30].
The city has several perennial surface water bodies. Among them, Deepor Beel, Borsola
Beel, Sarusola Beel, Dighali Pukhuri, and Silsako Beel play a crucial role in recharging
groundwater. The water from these surface water bodies seeps through their surfaces and
contributes to groundwater recharge.
The recharge from surface water bodies was quantified using Equation (3)
RS= Area ×water available days ×seepage factor (3)
where R
S
is the recharge from surface water bodies, and the seepage factor is the amount of
water that can be percolated through the soil to the groundwater. The area of the surface
water bodies was calculated using ArcGIS 10.7.1.
The total natural groundwater recharge was estimated using Equation (4)
RN= RR+ RS(4)
where RNis the total amount of natural recharge.
3.2. Assessments of Urban Groundwater Recharge
The urban components that contribute to groundwater recharge include leakages from
the water supply, domestic wastewater, and industrial wastewater. To calculate the recharge
from water supply leakages, it is necessary to know the exact volume of water supplied to
households and the percentage of leakages. Data on the volume of water supply and the
population covered were collected from the Guwahati Metropolitan Drinking Water and
Sewerage Board [
26
]. The volume of water received by households was not exactly equal to
the volume of water supplied because there was a leakage factor of 15%. Leakage of water
supply happens because of poor conditions of the infrastructure. The consumptive use is
approximately 20 L per capita per day (LPCD). After consumption, the remaining volume
of water is considered to contribute to wastewater [
31
]. The population without access to
the water supply extracts groundwater to fulfill their demand. The wastewater produced
by those households is transported into drainage channels and contributes to recharge.
In the case of industries, the effluents produced were treated in situ where effluent
treatment plants (ETPs) were available. The rest of the industries disposed of their effluents
into open drains, which also contributed to groundwater recharge. Approximately 90% of
the domestic and industrial wastewater contributes to groundwater recharge [31].
Total urban groundwater recharge is estimated using Equation (5)
RU= Ws+ Dw+ I (5)
where W
s
is the leakage from water supply mains, D
w
is the leakage from domestic
wastewater, and Iwis the leakage from industrial wastewater.
Net groundwater recharge was then calculated by combining the natural and urban
recharge using Equation (6)
RT= RN+ RU(6)
Urban Sci. 2024,8, 187 6 of 11
where R
T
is the total groundwater recharge, R
N
is the total natural recharge, and R
U
is the
total urban recharge.
4. Results
4.1. Total Natural Groundwater Recharge
Total natural groundwater recharge for the year 2022 was calculated by subtracting the
combined effects of evapotranspiration and runoff from the total annual rainfall. The remaining
portion of rainfall, after accounting for these losses, was considered the amount available
for groundwater recharge. Since the rate of recharge was controlled by both the presence of
impervious surfaces and the lithology of the study area [
20
], the area available for recharge was
calculated separately for each geomorphological unit. The study area includes the following
primary geomorphological features: an alluvial plain and a residual hill. The alluvial plain,
which is more conducive to recharge, covers an area of
98.66 sq. km
, while the residual hill,
characterized by a less permeable formation, covers an area of 46.34 sq. km.
To account for the differences in infiltration capacity between these units, the following
infiltration factors were applied: 0.22 and 0.11 for the alluvial plain and residual hills,
respectively (Figure 2and Table 3). The total volume of groundwater recharge from rainfall
was calculated to be 7.99 MCM/yr, based on these area-specific infiltration rates (Table 3).
Additionally, Guwahati city contains several large perennial surface water bodies,
which play a significant role in the groundwater recharge process. These water bodies act
as natural conduits, facilitating the seepage of water into the underlying aquifers. Recharge
from these perennial surface water bodies was calculated separately and estimated to be
3.11 MCM/yr (Table 4). Combining the recharge contributions from both rainfall and
perennial surface water bodies, the total natural groundwater recharge for the year 2022
amounted to 11.1 MCM/yr.
Table 4. Natural groundwater recharge from perennial surface water bodies.
Surface
Water Body
Geomorphic
Unit
Area
(km2)
Water Available
(days)
Seepage Factor
(mm/day) *
Total Recharge
(MCM/yr)
Deepor Beel Alluvial
plains 4.1 365 1.4 2.09
Sarusola and
Borsola Beel
Alluvial
plains 1.38 365 1.4 0.72
Dighali
Pukhuri
Alluvial
plains 0.04 365 1.4 0.02
Silsako Beel Alluvial
plains 0.55 365 1.4 0.28
Total 6.07 3.11
Note: MCM/yr—million cubic meters per year; * seepage factor [30].
4.2. Total Urban Groundwater Recharge
The accurate estimation of urban groundwater recharge is essential for understanding
water sustainability in urban areas. A key factor in this estimation is the knowledge of the
total water supplied to meet a city’s demand. In 2022, a total of 66.5 MLD (24.27 MCM/yr)
was supplied to serve 42.61% of the population through various agencies (Table 1). It is
assumed that 15% of the water supplied through urban infrastructure leaks [
26
], which is
categorized as unaccounted for water (UFW). This leakage is calculated to be 9.98 MLD
(3.64 MCM/yr). Since the water supply pipelines are located underground, this leakage
can contribute directly to groundwater recharge.
After accounting for the leakage of 9.97 MLD (3.64 MCM/yr), the net amount of water
distributed to end-users is estimated to be 56.53 MLD (20.63 MCM/yr). The potential do-
mestic wastewater production can be estimated based on the assumption of a consumptive
use of 20 LPCD [
24
], amounting to 46.61 MLD (16.97 MCM/yr). According to the Central
Urban Sci. 2024,8, 187 7 of 11
Public Health and Environmental Engineering Organization (CPHEEO), Government of
India, the recommended domestic water requirement in urban areas is 135 LPCD. Since
this level is often unmet by the public water supply, a volume of groundwater is extracted
to make up the deficit, amounting to 91.11 MLD (33.27 MCM/yr).
After accounting for consumptive use, the potential domestic wastewater production is
estimated to be 77.61 MLD (28.34 MCM/yr) (Table 5). As suggested by Lerner et al. (1990) [
31
],
it is assumed that 90% of the wastewater produced contributes to groundwater recharge. This
results in an estimated recharge from domestic wastewater of 111.68 MLD (40.78 MCM/yr).
Table 5. Estimation of potential domestic wastewater production from the water supply and ground-
water abstraction.
Source Population Actual Water
Supply (MLD)
Consumptive
Use (MLD)
Potential Wastewater
Production (MLD)
Water supply
501,094 56.53 10.02 46.61
Groundwater
674,906 91.11 13.5 77.61
Note: MLD—million liter per day.
Regarding industrial wastewater, data from the Assam Pollution Control Board (APCB)
indicate that out of 2.2 MCM/yr of wastewater produced, 0.36 MCM/yr is directly dis-
charged into drains. By applying the same 90% recharge contribution, the recharge from
industrial wastewater is estimated to be 0.32 MCM/yr (Figure 3).
Urban Sci. 2024, 8, x FOR PEER REVIEW 7 of 11
of India, the recommended domestic water requirement in urban areas is 135 LPCD. Since
this level is often unmet by the public water supply, a volume of groundwater is extracted
to make up the deficit, amounting to 91.11 MLD (33.27 MCM/yr).
After accounting for consumptive use, the potential domestic wastewater production
is estimated to be 77.61 MLD (28.34 MCM/yr) (Table 5). As suggested by Lerner et al.
(1990) [31], it is assumed that 90% of the wastewater produced contributes to groundwater
recharge. This results in an estimated recharge from domestic wastewater of 111.68 MLD
(40.78 MCM/yr).
Table 5. Estimation of potential domestic wastewater production from the water supply and
groundwater abstraction.
Source Population
Actual Water
Supply (MLD)
Consumptive Use
(MLD)
Potential Wastewater
Production (MLD)
Water supply 501,094 56.53 10.02 46.61
Groundwater 674,906 91.11 13.5 77.61
Note: MLD—million liter per day.
Regarding industrial wastewater, data from the Assam Pollution Control Board
(APCB) indicate that out of 2.2 MCM/yr of wastewater produced, 0.36 MCM/yr is directly
discharged into drains. By applying the same 90% recharge contribution, the recharge
from industrial wastewater is estimated to be 0.32 MCM/yr (Figure 3).
Figure 3. Flowchart showing the different components of urban groundwater recharge fractions
[26,31].
Figure 3. Flowchart showing the different components of urban groundwater recharge fractions [26,31].
Urban Sci. 2024,8, 187 8 of 11
By combining the contributions from water supply leakage, domestic wastewater, and
industrial wastewater, the total urban groundwater recharge is estimated to be 44.74 MCM/yr
(Figure 3). This recharge is valuable in sustaining groundwater resources in urban areas
and highlights the need to manage both water supply infrastructure and effective disposal
of wastewater to maintain urban water sustainability.
5. Discussion
Groundwater recharge in Guwahati city is heavily influenced by human activities,
often exceeding natural recharge processes. In 2022, the study area recorded an estimated
recharge of 55.84 MCM, with urban infrastructure contributing a disproportionate amount
of 44.74 MCM, approximately four times greater than the 11.1 MCM from natural processes
(Table 6). The significant volume of urban recharge, largely due to the absence of wastew-
ater treatment facilities, poses a serious risk of groundwater contamination, particularly
from high nitrate loads [
32
], highlighting a critical vulnerability in urban water resources
management. Additionally, sewer leakages could further threaten groundwater quality in
the city [33].
Table 6. Comparison of decadal groundwater recharge in Guwahati city.
Assessment Year Investigating Agency Groundwater Recharge (MCM/yr)
2004–2006 CGWB 116.27
2017 CGWB 95.38
2022 CGWB 53.52
2022 Present study 55.84
Note: MCM/yr—million cubic meters per year.
Similar patterns of urban control in groundwater recharge are evident in other densely
populated megacities of India and globally. For instance, Hyderabad’s urban recharge
exceeds natural recharge by 11 times, driven by expansive infrastructure and increased
water use [
7
]. Similarly, in Solapur, rising water consumption is correlated with a substantial
increase in urban recharge [
20
]. In Yogyakarta, Indonesia, domestic wastewater infiltration
and septic tank leakage have contributed to high groundwater recharge [
34
]. Likewise,
groundwater quality risks emerge as a primary concern because of potential contamination
from wastewater. In Kolkata’s wetlands, excessive groundwater pumping in urban areas
often results in recharge from polluted sources, exacerbating the potential for groundwater
contamination [
35
]. In Bengaluru, India, a model-based groundwater budget revealed
a stark imbalance between natural and anthropogenic recharge. While natural recharge
was estimated to be 183 MLD, the anthropogenic contribution amounted to 791 MLD,
creating a negative groundwater balance of 40 MLD [
24
]. This demonstrates how urban
recharge, while quantitatively significant, can lead to overextraction and increased reliance
on contaminated sources, thereby aggravating groundwater quality concerns.
Groundwater recharge in urban areas varies with time because of changes in water
supply volume, the development of sewage treatment facilities, population growth, and
land use and land cover patterns. Hydrogeological conditions, precipitation patterns, and
irrigation practices further complicate recharge dynamics [
36
]. Human interventions on
vegetation, irrigation, and water use also affect the storage of groundwater resources [
37
].
In the study area, a decadal comparison reveals a steady decline in groundwater recharge
(Table 6), highlighting the effects of rapid urbanization and population growth. Nath et al.
(2021) [
38
] linked this decline to an increase in built-up areas, where impervious surfaces
limit natural recharge pathways, adding stress to the city’s groundwater resources.
The Central Ground Water Board (CGWB), an apex body under the Ministry of Jal
Shakti, Government of India, is responsible for the exploration, monitoring, and assessment
of groundwater resources and estimates groundwater reserves annually. However, their
resource estimation methods neither account for water lost through evapotranspiration and
Urban Sci. 2024,8, 187 9 of 11
runoff, nor for water input from urban sources. As a result, they advise against using CGWB
estimates for cities with populations exceeding 1,000,000. Since most megacities worldwide
experience significant anthropogenic influences on groundwater recharge, calculations
based solely on direct rainfall and surface water bodies are insufficient. Studies have shown
that urbanization alters groundwater recharge by introducing various new sources for
recharge [
39
,
40
]. For megacities with populations exceeding one million, such as Guwahati
and many others worldwide, more comprehensive methodologies are needed.
6. Conclusions
This study highlights the significant role of urban infrastructure in groundwater
recharge, with leakages from water supply networks and domestic and industrial wastew-
ater contributing substantially. The absence of a sewage treatment facility results in the
direct discharge of wastewater into streams, further degrading groundwater quality. To
prevent contamination, it is important to construct and operate sewage treatment facilities.
Additionally, strategies should be implemented to reduce potable water loss by addressing
leakages in the water supply network. Urbanization must be carefully planned, and green
infrastructure must be integrated to preserve natural recharge processes. While urban
infrastructure can significantly enhance recharge rates, it also introduces contamination
pathways, particularly in the absence of effective wastewater treatment systems. As cities
grow and their water demands increase, the challenge of balancing urban recharge with
groundwater quality and sustainable management becomes increasingly urgent. While
this study provides a basic estimate of groundwater recharge, a more detailed assessment
incorporating evapotranspiration and runoff data is recommended for greater accuracy.
Author Contributions: Conceptualization, R.C. and J.D.; methodology, R.C. and J.D.; software,
J.D. and B.N.; validation, R.C. and J.D.; formal analysis, J.D.; investigation, J.D.; resources, R.C.;
data curation, J.D. and B.N.; writing—original draft preparation, R.C. and J.D.; writing—review
and editing, R.C. and B.N.; visualization, J.D. and B.N.; supervision, R.C.; project administration,
R.C.; funding acquisition, None. All authors have read and agreed to the published version of
the manuscript.
Funding: This research received no external funding.
Data Availability Statement: The original contributions presented in the study are included in the
article, further inquiries can be directed to the corresponding authors.
Acknowledgments: The authors would like to thank the Regional Meteorological Department,
Guwahati, and Guwahati Metropolitan Drinking Water and Sewerage Board for sharing their data
with us.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
van der Gun, J. Groundwater resources sustainability. In Global Groundwater; Elsevier: Amsterdam, The Netherlands, 2021;
pp. 331–345.
2.
Sarami-Foroushani, T.; Balali, H.; Movahedi, R.; Kurban, A.; Värnik, R.; Stamenkovska, I.J.; Azadi, H. Importance of good
groundwater governance in economic development: The case of western Iran. Groundw. Sustain. Dev. 2023,21, 100892. [CrossRef]
3.
Kumar, P.J.S.; Schneider, M.; Elango, L. The state-of-the-art estimation of groundwater recharge and water balance with a special
emphasis on India: A critical review. Sustainability 2021,14, 340. [CrossRef]
4.
Li, R.; Zhu, G.; Lu, S.; Sang, L.; Meng, G.; Chen, L.; Jiao, Y.; Wang, Q. Effects of urbanization on the water cycle in the Shiyang
River basin: Based on a stable isotope method. HESS 2023,27, 4437–4452. [CrossRef]
5.
Han, S.; Slater, L.; Wilby, R.L.; Faulkner, D. Contribution of urbanisation to non-stationary river flow in the UK. J. Hydrol. 2022,
613, 128417. [CrossRef]
6. Lerner, D.N. Groundwater recharge in urban areas. Atmos. Environ. Part B 1990,24, 29–33. [CrossRef]
7.
Wakode, H.B.; Baier, K.; Jha, R.; Azzam, R. Impact of urbanization on groundwater recharge and urban water balance for the city
of Hyderabad, India. Int. Soil Water Conserv. Res. 2018,6, 51–62. [CrossRef]
8.
Rezaei, A.R.; Ismail, Z.B.; Niksokhan, M.H.; Ramli, A.H.; Sidek, L.M.; Dayarian, M.A. Investigating the effective factors influencing
surface runoff generation in urban catchments—A review. Desalin. Water Treat 2019,164, 276–292. [CrossRef]
Urban Sci. 2024,8, 187 10 of 11
9.
Eshtawi, T.; Evers, M.; Tischbein, B. Quantifying the impact of urban area expansion on groundwater recharge and surface runoff.
Hydrolog. Sci. J. 2016,61, 826–843. [CrossRef]
10.
Huong, H.T.L.; Pathirana, A. Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam. HESS
2013,17, 379–394. [CrossRef]
11.
Kuruppath, N.; Raviraj, A.; Kannan, B.; Sellamuthu, K.M. Estimation of groundwater recharge using water table fluctuation
method. Int. J. Curr. Microbiol. Appl. Sci. 2018,7, 3404–3412. [CrossRef]
12.
Minnig, M.; Moeck, C.; Radny, D.; Schirmer, M. Impact of urbanization on groundwater recharge rates in Dübendorf, Switzerland.
J. Hydrol. 2018,563, 1135–1146. [CrossRef]
13.
Rutsch, M.; Rieckermann, J.; Krebs, P. Quantification of sewer leakage: A review. Water Sci. Technol. 2006,54, 135–144. [CrossRef]
[PubMed]
14.
Prigiobbe, V.; Giulianelli, M. Quantification of sewer leakage by a continuous tracer method. Water Sci. Technol. 2011,64, 132–138.
[CrossRef]
15.
Vineeth, V.; Ramachandran, P. Components of urban ground water recharge in Bengaluru, India. Urban Water J. 2022,20,
1627–1634.
16.
Tubau, I.; Vázquez-suñé, E.; Carrera, J.; Valhondo, C.; Criollo, R. Quantification of groundwater recharge in urban environments.
Sci. Total Environ. 2017,592, 391–402. [CrossRef]
17.
Rammal, M.; Archambeau, P.; Erpicum, S.; Orban, P.; Brouyère, S.; Pirotton, M.; Dewals, B. Technical note: An operational
implementation of recursive digital filter for base flow separation. Water Resour. Res. 2018,54, 8528–8540. [CrossRef]
18.
Weatherl, R.K.; Salgado, M.J.H.; Ramgraber, M.; Moeck, C.; Schirmer, M. Estimating surface runoff and groundwater recharge in
an urban catchment using a water balance approach. Hydrogeol. J. 2021,29, 2411–2428. [CrossRef]
19.
Yang, Y.; Lerner, D.N.; Barrett, M.H.; Tellam, J.H. Quantification of groundwater recharge in the city of Nottingham, UK. Environ.
Geol. 1999,38, 183–198. [CrossRef]
20.
Naik, P.K.; Tambe, J.A.; Dehury, B.N.; Tiwari, A.N. Impact of urbanization on the groundwater regime in a fast growing city in
central India. Environ. Monit. Assess. 2008,146, 339–373. [CrossRef]
21.
Vázquez-suñé, E.; Carrera, J.; Tubau, I.; Sanchez-Vila, X.; Soler, A. An approach to identify urban groundwater recharge. Hydrol.
Earth Syst. Sci. 2010,14, 2085–2097. [CrossRef]
22.
CGWA. Consolidated MoJS Guideline to Regulate and Control Groundwater Extraction in India. Ministry of Water Resources,
River Development and Ganga Rejuvenation, Government of India. 2023. Available online: https://cgwa-noc.gov.in/ (accessed
on 12 January 2024).
23.
Madhok, A.K. Enhancing water Use Efficacy. Central Water Commission, Roorkee Water Conclave, 2020, p. 159. Available online:
https://www.iitr.ac.in/rwc2020/pdf/theme_concepts_abstracts-book.pdf (accessed on 24 January 2024).
24.
Tomer, S.K.; Sekhar, M.; Balakrishnan, K.; Malghan, D.; Thiyaku, S.; Gautam, M.; Mehta, V.K. A model-based estimate of the
groundwater budget and associated uncertainties in Bengaluru, India. Urban Water J. 2021,18, 1–11. [CrossRef]
25.
Awasthi, S.; Jain, K.; Bhattacharjee, S.; Gupta, V.; Varade, D.; Singh, H.; Narayan, A.B.; Budillon, A. Analyzing urbanization
induced groundwater stress and land deformation using time-series Sentinel-1 datasets applying PSInSAR approach. Sci. Total
Environ. 2022,844, 157103. [CrossRef] [PubMed]
26.
GMDW & SB. Guwahati Metropolitan Drinking Water and Sewerage Board. 2024. Available online: https://gmdwsb.assam.gov.
in/ (accessed on 10 May 2024).
27.
Roy, I. Hydrogeological framework and impact of urbanization on groundwater regime in greater Guwahati area, Assam, NER.
CGWB. Unpublished work. 2007.
28.
Climate Engine. On-Demand Insights from Climate and Earth Observations Data. 2024. Available online: https://www.
climateengine.org (accessed on 10 May 2024).
29. Beven, K. The era of infiltration. Hydrol. Earth Syst. Sci. 2021,25, 851–866. [CrossRef]
30.
CGWB. Report of the Groundwater Resource Estimation Committee. Ministry of Water Resources, River Development and Ganga
Rejuvenation. Government of India, Faridabad. 2015. Available online: https://cgwb.gov.in/ (accessed on 12 January 2024).
31. Lerner, D.N.; Issar, A.S.; Simmers, I. Groundwater recharge: A guide to understanding and estimating natural recharge. In IAH
International Contributions to Hydrogeology, 8th, ed.; Taylor and Francis: Rotterdam, The Netherlands, 1990.
32.
Vystavna, Y.; Diadin, D.; Rossi, P.M.; Gusyev, M.; Hejzlar, J.; Mehdizadeh, R.; Huneau, R. Quantification of water and sewage
leakages from urban infrastructure into a shallow aquifer in East Ukraine. Environ. Earth Sci. 2018,77, 748. [CrossRef]
33.
Eiswirth, M.; Hötzl, H. The Impact of Leaking Sewers on Urban Groundwater. Available online: https://users.pfw.edu/isiorho/
G300Eiswirth-Hoetzl_IAH_Nottingham_1997.pdf (accessed on 20 January 2024).
34.
Wilopo, W.; Putra, D.P.E. Groundwater recharge estimation using groundwater level fluctuation patterns in unconfined aquifer of
Yogyakarta City, Indonesia. Kuwait J. Sci. 2021,48, 1–11. [CrossRef]
35.
Sahu, P.; Michael, H.A.; Voss, C.I.; Sikdar, P.K. Impacts on groundwater recharge areas of megacity pumping: Analysis of potential
contamination of Kolkata, India, water supply. Hydrolog. Sci. J. 2013,58, 1340–1360. [CrossRef]
36.
Bhanja, S.N.; Mukherjee, A.; Rangarajan, R.; Scanlon, B.R.; Malakar, P.; Verma, S. Long-term groundwater recharge rates across
India by in situ measurements. Hydrol. Earth Syst. Sci. 2019,23, 711–722. [CrossRef]
Urban Sci. 2024,8, 187 11 of 11
37.
Scanlon, B.R.; Fakhreddin, S.; Rateb, A.; Graaf, I.D.; Famiglietti, J.; Gleeson, T.; Grafton, R.Q.; Jobbagy, E.; Kebede, S.; Kolusu, S.R.;
et al. Global water resources and the role of groundwater in a resilient water future. Nat. Rev. Earth Environ. 2023,4, 87–101.
[CrossRef]
38.
Nath, B.; Ni-Meister, W.; Choudhury, R. Impact of urbanization on land use and land cover change in Guwahati city, India and its
implication on declining groundwater level. Groundw. Sustain. Dev. 2021,12, 100500. [CrossRef]
39. Sharp, J. The impacts of urbanization on groundwater systems and recharge. AQUA Mundi. 2010,1, 2719.
40.
Siddik, M.S.; Tulip, S.S.; Rahman, A.; Islam, M.Z.; Haghighi, A.T.; Mustafa, S.M.T. The impact of land use and land cover change
on groundwater recharge in northwestern Bangladesh. J. Environ. Manag. 2022,315, 115130. [CrossRef]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual
author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to
people or property resulting from any ideas, methods, instructions or products referred to in the content.
