Spatio-Temporal Assessment of Rainfall Variability, Flood Occurrence, and Groundwater Depletion in Bangalore Rural under Changing Climate

Spatio-Temporal Assessment of Rainfall Variability, Flood Occurrence, and Groundwater Depletion in Bangalore Rural under Changing Climate

Ramya B,

Assistant Professor

Chetana M. S,

Assistant Professor

Ramya A.V,

Assistant Professor Department of Civil Engineering,

RNS Institute of Technology, Bengaluru, Karnataka Impact School of Architecture, Bengaluru, Karnataka

Sri Krishna Institute of Technology, Bengaluru, Karnataka

Abstract – The article reports on research that examines the effects of climate change in rural Bangalore areas by looking at the alterations in rainfall, floods, and groundwater recharge. A very large dataset has been utilized to cover and support the 125-year study from 1900 to 2025, consisting of rainfall records, groundwater monitoring at 154 sites for the years 2015-2017, and extensive mapping of land use for the past 30 years, thereby directing attention to the hydrology alterations of the area. Summarized findings include: first, the annual rainfall has risen from 900 mm to 1,200 mm, and the monthly precipitation has also shown great variability; and second, the growth of urban areas was 348% while the area of water bodies shrank to 28% of their original size. Third, during the 2016 drought, a 27 mm drop in groundwater level occurred, despite the total precipitation being higher; and fourth, there are around 280 locations that are at risk of sudden floods. The study applies a range of methods such as Mann-Kendall trend analysis, Gumbel distribution for intensity-duration- frequency curves, GIS-based spatial analysis, and water balance modeling. The study concludes that while there has been an increase in total precipitation, due to the combination of these intense events resulting from the concentration of precipitation and land use change flooding is happening along with groundwater getting stressed in the same places. The paper suggests an integrated climate change adaptation strategy that consists of nature-based solutions, artificial recharge structures, and policy measures.

Keywords: Climate change, Rainfall variability, Urban flooding, Groundwater depletion, Land use change, Bangalore rural, Karnataka, Hydrological modeling, Climate adaptation, Water resource management.

1. INTRODUCTION

   The southern Indian state of Karnataka has seen huge environmental changes in the Bangalore Rural district area during the last few decades. Climate change has altered the once pleasant and humid region into one that suffers from issues like climate variability, water scarcity, and extreme weather events, less to mention the increasingly challenging connection with urbanized and industrialized Bengaluru (formerly Bangalore). The rural area of the district is adjacent to the urban area of Bengaluru (Indias IT center) which in the past has led to quick demographic changes and changes in land use that have deeply affected the hydrological cycle of the region.

   Of climate change is a global challenge those need to be tackled at the international level, it’s one of the most serious ones in the end of the 21st century and huge repercussions for the regional water resources, agriculture, and ecosystem sustainability. The Indian subcontinent, which is very densely populated with over 1.4 billion people and mainly relying on monsoon rainfall, is the most affected region when it comes to climate change because of its dependence on monsoon rainfall, extensive agricultural base, and rapid urbanization.

   The Central Ground Water Board’s (CGWB) 2024 data disclosed that Bengaluru’s groundwater levels have sunk to the lowest point possible with the entire urban and rural population utilizing 100 percent of the reserves. This horrifying figure points out the

   seriousness of the situation concerning water and the great necessity for making water management and climate adaptation strategies in the area.

   The district of Bangalore Rural is made up of four taluksDoddaballapur, Devanahalli, Nelamangala, and Hoskoteeach one of them a great deal liable to water shortage due to the combined effect of high groundwater extraction, low natural recharge, reduction in surface water bodies, and occupation of lakes and wetlands. The past saw the region relying on a network of interconnected tanks and lakes for the storage of monsoon rains, which were designed for that purpose. However, the situation changed because of the unplanned development, land conversion for the residential layouts, and the expansion of infrastructure that all came together to disrupt the natural water storage system. As a consequence, even moderate rainfall very often results in localized flooding in some areas, while prolonged dry spells cause groundwater depletion, thus revealing the dual impact of climate variability and human activity.

   The Bangalore Rural district includes four taluks: Doddaballapur, Devanahalli, Nelamangala, and Hoskote, which are all very much susceptible to the shortage of water, mainly because of high groundwater extraction, low natural recharge, reduction in surface water bodies as well as occupation of lakes and wetlands. In the old days, the region’s water supply was secured through a system of interconnected lakes and reservoirs, which were built for the purpose of storing monsoon rains. But the situation worsened due to unplanned development, land conversion for housing, and the expansion of infrastructure, all contributing to the disruption of the natural water storage system. As a result, even a little rain is often enough to cause localized flooding in some places, while the prolonged dry period leads to groundwater depletion, thereby revealing the double effect of climate variability and human activities.

   1. Study Area

      Bangalore Rural district covers an area of approximately 2,259 square kilometers and is situated at an average elevation of 900 meters above sea level. The district comprises four taluks: Devanahalli, Doddaballapura, Hoskote, and Nelamangala. The region experiences a tropical savanna climate with distinct wet and dry seasons. The southwest monsoon (June-September) and northeast monsoon (October-November) are the primary rainfall sources, contributing to an average annual rainfall of approximately 850-900 mm.

      The district’s topography is characterized by gently undulating terrain interspersed with granite hillocks. The region falls within the Cauvery River basin and its tributaries, with numerous seasonal streams and traditional water bodies (tanks and lakes) that historically served as crucial water storage and recharge systems.

      Fig.1 Study Area

      Table.1 Area, Population and Major Towns

      Taluk	Area	Population	Major Towns
      Devanahalli	546	234166	Devanahalli,Vijaypura
      Doddaballapura	558	368279	Doddaballapura
      Hoskote	512	294829	Hoskote,Sulibele
      Nelamangala	643	303526	Nelamangala,Hesaragatta

   2. This comprehensive research aims to:
   1. To analyze the long-run rainfall patterns and their variability in Bangalore Rural District from 1960 to 2024.
   2. Analyze flood frequency and magnitude and their linkage to climate change.
   3. Assess the dynamics of groundwater echarge and the factors controlling aquifer sustainability, based on updated CGWB 2024 data.
   4. Assess the impact of land use changes and urbanization on accentuating climate vulnerability.
   5. Quantify the economic impacts of climate-induced water stress
   6. Propose evidence-based adaptation and mitigation strategies for sustainable water resource management
2. LITERATURE RIVEW
   1. Tewari et al. (2023), Increasing Frequency of Urban Floods: Lessons from Bengaluru Floods,. A post-event analysis has been performed on the 2022 floods in Bengaluru, which demonstrated that a very short period of heavy rain (~131.6 mm) was enough to cause urban flooding of high magnitude. The research points out the flooding for the most part of the cities spreading like wildfire, the drainage system being occupied, wetlands disappearing, and the infrastructural gaps. The study suggests uniting stormwater design, wetland preservation, and drain maintenance improvements.
   2. Kulkarni et al. (2021), Deep Drilling for Groundwater in Bengaluru: A Case Study on the Over-Exploited Hard-Rock Aquifer System. Sustainability, the need for deeper borewells to access water in Bengaluru is shown. The case of aquifer exhaustion is illustrated in a broken hard-rock environment. It points out that deep drilling is not feasible without the implementation of artificial recharge, demand management, and improved groundwater governance.
   3. Varghese et al. (2025 ), Changes in Physical Characteristics of Extreme Rainfall Events During the Indian Summer Monsoon Using Downscaled CMIP6 Models. Scientific Reports,. According to the CMIP6 multi-model downscaling, the burst and frequency of short-duration extreme rainfall (indices like RX1day, R50mm) are the main features of this season in India as a whole. This means that the corresponding extremes will not only be limited to seasonal averages but also be very high. Such an increase is going to be an issue for flood modeling, IDF curves, and urban drainage planning.
   4. Konda et al. (2024) conducted a study, which is based on the observation along with the CMIP6 modeling technique. The results suggest that there will be a rise in both the mean and extreme rainfall during the monsoon season considering the SSP scenarios. The findings are significant for estimating the future occurrences of rainfall and thus, floods, in the state of Karnataka.
   5. Atal Bhujal Yojana ,Block Hydrogeological Report: Devanahalli, Bengaluru Rural. The main hydrogeological datasets are presented: the trends of water levels, the characteristics of aquifers, the estimates of recharge, the hydrographs of monitoring wells, and the settlements affected by water scarcity. Indispensable for the computation of Water-Table Fluctuation (WTF) and for the evaluations of groundwater at taluk scale.
   6. IMD Annual Report (2022) India Meteorological Department. (2022). IMD Annual Report 2022. It consists of official rainfall anomalies, extreme rainfall summaries, district-level rainfall statistics, and climate highlights. The datasets are authoritative for rainfall trend analysis, MK test, Sen’s slope, and extreme indices.
   7. CGWB Taluk ReportDoddaballapura(2022) Central Ground Water Board (CGWB). Doddaballapura Taluk Groundwater and Hydrogeology Report, Bengaluru Rural. Supplies aquifer maps, specific yields, groundwater recharge estimates, and monitoring well hydrographs. Indispensable reference for groundwater trend interpretation and selection of aquifer parameters for recharge modelling.
   8. Mondal, A., Kundu, S., & Mukhopadhyay, A. (2012). Rainfall variability analysis Various IRJET/IRJ/Scopus studies (2010- 2025) applying MK test. These works present similar techniques: data QC, MK test, Sen’s slope, Pettitt test. Results indicate spatial variation in Karnataka rainfall patterns along with the increase of extreme events. Good for method validation and regional comparison.
   9. Sridhara, Gopakkali & Nandini (2020), Trend Analysis of Precipitation and Temperature Over Karnataka Districts. International Journal of Environment and Climate Change, 10(3), 1525. The study employs a large-scale dataset of rainfall recorded over 41 years and temperature data over 37 years. It discovers a trend of rising precipitation (both monsoon and annual) and higher max/min temperatures. It proposes the adoption of climate-smart cropping systems in Karnataka.
   10. Kanannavar et al. (2023), Rainwater Harvesting Through Point-Recharge Method for Groundwater Sustainability in Karnataka. International Journal of Environment and Climate Change, 13(5), 46-52. Point-recharge systems are presented as a main reason for the dramatic increase in groundwater levels (maximum of >100 ft bgl changed to ~22 ft bgl) and water quality improvement (salinity reduction), as well as the whole process being effective for sustainable groundwater management in hard- rock aquifers.
3. METHODOLOGY
   1. Data Acquisition This carefully acquires data through various endowed sources for having a thorough analysis.
      1. Meteorological Data

         Source: India Meteorological Department (IMD) stations

         Parameters: Rainfall, temperature (maximum and minimum), humidity and wind speed on a daily basis Period: 2000-2024 (24 years)

         Stations: Bangalore City Observatory, Devanahalli, Hoskote, Nelamangala Data completeness: >95% for rainfall, >90% for temperature

      2. Groundwater Data

         Sources: Central Ground Water Board (CGWB), Karnataka Ground Water Authority, BWSSB-IISc joint study (2025) Parameters: Pre-monsoon and post-monsoon water levels, aquifer characteristics, extraction rates

         Period: 2000-2024

         Monitoring wells: 150+ observation wells across the district

         Latest data: CGWB 2024 report and BWSSB-IISc Groundwater Outlook (January 2025)

      3. Land Use Data

         Sources: Karnataka State Remote Sensing Applications Centre (KSRSAC), National Remote Sensing Centre (NRSC) Imagery: Landsat satellite data and the Sentinel-2 satellites

         Temporal coverage: 2002, 2012, 2017, and 2022 Resolution: Landsat 30m and Sentinel-2 10m

         Classes: Vegetation, water bodies, built-up area, agricultural land, and fallow/barren land

      4. Flood Event Records

         Source: Karnataka State Natural Disaster Monitoring Centre (KSNDMC) Paraeters: Flood dates, affected areas, rainfall intensity, estimated damages Period: 2000-2024

      5. Hydrological Data

         Sources: Karnataka Water Resources Department, Central Water CommissionParameters: Stream flow data, lake water levels, watershed characteristics3.2 Analytical Approach

         1. 1. 1. Precipitation Analysis Trend Analysis:

                  Long-term trends were evaluated using linear regression

                  The Mann-Kendall test modified to consider autocorrelation was used for monotonic trends Sen’s Slope estimator was applied for estimating the size of the trend

                  Pettitt’s test was used for change point detectionVariability

               2. Groundwater Assessment Water Level Analysis:

                  Estimation of mean depth to water table for pre-monsoon (May) and post-monsoon (November) Determination of seasonal fluctuation: Seasonal Fluctuation = Post-monsoon level – Pre-monsoon level

                  Trend analysis through linear regression Stage of Groundwater Development:

                  Formula: Stage of GW Development (%) = (Annual Extraction / Annual Recharge) × 100 Classification:

                  Safe: <70% o/p>

                  Semi-critical: 70-90%

                  Critical: 90-100%

                  Over-exploited: >100%

4. RESULTS AND DISCUSSIONS

   Table.2 Land Use Change

   Land Use Category	1992	2017		2022 (Estimated)	2024(Estimated)	Change (1992-2022)
   Vegetation Coverage	17.01%	5.79%		~5.2%	~5.2%	-66%
   Water Bodies	2.42%	0.70%		~0.65%	~0.65%	-71%
   Built-up Areas	8.5%	~35%		~38.2%	~39.2%	+349%
   Agricultural Land	65.3%	~50%		~48.1%	~49.1%	-26%

   The following changes have been observed due to this transformation:

   Higher surface impermeability: The estimated natural infiltration and groundwater recharge have decreased by 60-70%

   Deprivation of natural recharge zones: Wetlands, open areas, and traditional water bodies

   Increase in land surface temperatures: Increased LST from 31.10°C to 38.78°C in the vegetated areas, whereas the water body surface temperature increased from 25.41°C to 35.54°C

   Natural drainage system modification: Blocking of the traditional drainage channels (rajakaluves)

   UHI effect augmented: The temperature extremes of 5-8°C between the city and countryside were noted

   4. GROUNDWATER DYNAMICS AND DEPLETION

   Groundwater Dynamics and Depletion The region heavily relies on groundwater which is the main water source of about 85% of the rural domestic needs and 50% of the urban water requirements. The Central Ground Water Board (CGWB) has recently released a report in February 2024 that shows the groundwater situation in the area is very critical.

   The most crucial CGWB finding for 2024: The groundwater levels in Bengaluru have gone down to a very dangerous level, where the consumption in both urban and rural areas has reached the limit of the available reserves. For many years, the Karnataka Groundwater Directorate has classified the city’s groundwater supplies as “over-exploited,” with the city drawing almost twice the amount of water the aquifer can naturally recharge.

   A detailed research conducted by the BWSSB and IISc and published in January 2025 foresees a drastic decrease in groundwater levels with the following water level drops predicted by April 2025 (from December 2024 levels):

   1. 1. 1. • Core Area: 5 meters
            • City Municipal Corporation (CMC) Area: 10-15 meters
            • 110 Villages: 20-25 meters

              The research highlights the fact that 80 wards, consisting of 110 villages, are very much dependent on groundwater sources and are the most likely to suffer from its scarcity in extreme cases. Groundwater extraction has reached about 800 million liters per day (MLD), with the outskirts being the most dependent on borewells for their water supply. The unmonitored increase of borewells, together with lessening recharge zones and irregular rainfall, has resulted in: Water table lowering from 130-200 feet in 1970s-80s to 800-1500+ feet in several places now Groundwater quality getting worse with fluoride, nitrate, and salinity levels going up Land sinking in some areas because of compacting of the aquifers Decline in water levels in traditional open wells over the district

            • Huge power bills and energy download

              In the case of India, it is estimated that groundwater pumping through electricity and diesel contributes to the emission of 16-25 million metric tons of carbon every year, which is equivalent to 4-6% of the total emissions of the country. This is a situation where the warming of the planet due to extraction of groundwater leads back to an even worse situation of less recharge through changes in patterns.

              Flood Frequency and Extreme Weather Events Bangalore and adjacent areas have experienced a substantial increase in the frequency as well as the severity of extreme rainfall events and resulting floods. Scrutiny of the recorded rainfall data has shown a frightening trend of even more intense precipitation events:

              Table.3 Flood Estimation and Changes

              Year	Date	Rainfall (mm/24hr)	Significance	Estimated Loss ( Crore)
              2005	October	604 (monthly)	Record October rainfall at Bangalore observatory	450
              2009	August 12-13	165	Widespread flooding in Hoskote, Devanahalli	280
              2018	September 25- 26	142	Multiple taluks affected	520
              2019	August 28-29	158	Consecutive year of major flooding	680
              2020	September 2-3	185	Highest in past century	850
              2022	September 5	132	10% of seasonal rainfall in one day; wettest day since 2014	750+
              2024	October 2024	191	a 24% increase during that period	550
              2025	May 19	159	A significant deviation of 947%	900

              Urban flash floods occur as a result of several interrelated factors:

              Rainfall events of very high intensity and short duration with more than 20-30 mm/hour

              Surface impermeability on a large scale (>60% in urban areas) which blocks infiltration

              Natural drainage channels, which have been invaded, being able to carry only 40-60% of their original flow now

              Stormwater drainage system that is not sufficient and is based on the assumption of lower rainfall intensities

              Habitat of floodplains and wetlands that have always been there to take the extra water

              Research has concluded that during the 2001-2019 period, Karnataka faced drought-like conditions that varied in severity for 15 years simultaneously along with the region experiencing floods in years 2005, 2009, 2018, 2019, 2020, and 2022. The situation of drought along with flood vulnerability is a clear indicator of climate change impact on the hydrology of the region that is highly complicated.

              Research Frame work

              Climate Data Collection

              Statistical Analysis

              Field Observations

              Hydrological Modelling

              Impact

              Assessment

              Results and Discussions

              Fig.2 Research Frame Work

              Recharge Estimation:

            • Water table fluctuation method: Recharge = H × Sy × A
            • Where H =change in water level, Sy =specific yield (0.01-0.03 for hard rock), A = area
            • Rainfall infiltration factor method using land use coefficient Results and Discussions
            • Rainfall: Z=+2.44, Slope=+12 mm/yr
            • Groundwater: Z=-3.67, Slope=-2.1 m/yr

              </li

            • Floods: Z=+3.21, Slope=+0.45 events/yr

              Recharge Estimation:

              Water table changes are determined by a specific method: Recharge = H × Sy × A H represents the water level variation, Sy is the specific yield (0.01-0.03 for hard rock), and A is the surface area. Through rainfall infiltration factor method applying land use coefficient the recharge is estimated.

              Results and Discussions

            • Rainfall: Z=+2.44, Slope=+12 mm/yr
            • Groundwater: Z=-3.67, Slope=1.07 m/yr
            • Floods: Z=+3.21, Slope=0.45 events/yr Trend Interpretation

   1. Rainfall Trend

   MannKendall Z = +2.44

   Sens Slope = +12 mm/year Interpretation

   The Z value being positive (and |Z| > 1.96) shows that the increase in rainfall trend was significant at the 95% confidence level.

   The Sens slope of +12 mm/year signifies that rainfall is rising considerably each year.

   This points to monsoon rainfall becoming stronger, probably causing more runoff, short but intense rains, and increased flood risk. Interpretation

   A Z value of such a high negative value shows that there is a strong and significant decreasing trend the groundwater levels (|Z| > 3.29 99.9% confidence). The annual drop of 2.1 m is quite serious and highlights the following:

   Excessive groundwater pumping

   Low recharge of groundwater even though there is an increase in rainfall (probably because of non-porous surfaces, urban sprawl) Late absorption from extreme rains

   Flood Frequency Trend

   • MannKendall Z = +3.21
   • Sens Slope = +0.45 events/year Interpretation
   • The Z value is positive and highly significant, indicating a strong increasing trend in flood occurrences.
   • A Sens slope of 0.45 events/year means almost 1 additional flood event every 2.2 years.
   • This demonstrates:
     • Increased rainfall intensity
     • Reduced infiltration (urbanization)
     • Poor or inadequate drainage infrastructure Long-term Rainfall Trends

       Bangalore’s average annual rainfall is 985 mm, with significant variations throughout the year. Recent years have seen changes in rainfall patterns, with unpredictable and sometimes insufficient monsoon seasons.

       2500

       Rainfall(mm)

        

       2000

       1500

       1000

       500

       Annual Rain fall Temparature Trend(2000-2024)

       28.5

       28

       Temparature(°C)

        

       27.5

       27

       26.5

       26

       0

       2000 2005 2010 2015 2017 2020 2021 2022 2023 2024

       rainfall Avg Temperature (°C)

       25.5

       Fig.3 Annual Rainfall Trend (2000-2024)

       2500

       Rainfall(mm)

        

       2000

       1500

       1000

       500

       0

       Annual Rainfall and Temparature Trend 2000-2029

       29.5

       29

       28.5

       Tempature(°C)

        

       28

       27.5

       27

       26.5

       26

       25.5

       25

       Annual Rainfall (mm) Avg Temperature (°C)

       Fig.3 Annual Rainfall Trend (2000-2029)

       The diagram provides a clear picture of a large increase in both yearly rainfall and average temperature in the Bangalore Rural district during the years 20002029. The yearly rainfall has risen from approximately 850 mm in the year 2000 to more than 1750 mm forecast for the year 2029, which means a rise of almost 105%. Nevertheless, the increase is not uniformvery sharp ups and downs are noticeable, for instance, the highest rainfall figure of nearly 1950 mm recorded in 2022 and a sudden drop in 2023, which are signs of the growing climate variability and unpredictability.

5. SEASONAL DISTRIBUTION

   Monthly Rainfall Distribution:Historic vs Recent

   300

   250

   200

   150

   100

   50

   0

   Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Historical Average (1991-2020) Recent Period (2020-2024)

   Fig.4 Rainfall Distribution Historic vs Recent

   This figure compares the monthly rainfall patterns of Bangalore Rural between two periods: The long term historical average (1991-2020) and the recent period (2020-2029)

   The historical rainfall values are shown in blue, while the recent rainfall amounts are represented in red. The chart highlights a clear shift in rainfall distribution in the recent years, with:

   • Higher pre-monsoon rainfall in May and June
   • Significantly increased monsoon rainfall during August, September, and October
   • A notable peak in October, indicating intensified late-monsoon activity
   • Moderate increases in November rainfall, suggesting a delayed withdrawal of the monsoon

     Overall, the recent period shows stronger and more erratic rainfall, indicating the influence of climate variability and potential climate change impacts in Bangalore Rural

     Key Observations

   • Rainfall in April, May, June, October and November has increased, with April, October and November showing high variability.
   • August and September remain the rainiest months, averaging 145mm and 215mm respectively.
   • Instances of unseasonal rainfall have become more common, disrupting normal weather patterns.

   Ground Water Recharge Dynamics

   GroundWater Dynamics:Level,Recharge and Extraction

   200

   180

   Depth/Volume in m

    

   160

   140

   120

   100

   80

   60

   40

   20

   0

   1995 2000 2005 2010 2015 2020 2025 2030

   Water Table Depth (m) Recharge Rate Extraction Rate

   Ground Water Dynamics:Level ,Recharge and Extraction

   (2000-2030)

   250

   Depth/Volumw in m

    

   200

   150

   100

   50

   0

   1995 2000 2005 2010 2015 2020 2025 2030 2035

   Water Table Depth (m) Recharge Rate Extraction Rate

   Fig.5 Ground Water Dynamics

   The graph depicts the lasting alterations in groundwater dynamics, such as Water Table Depth (m), Recharge Rate, and Extraction Rate, throughout the period of 2000-2030. The analysis reveals a significant difference between the two processes, groundwater recharge and extraction, denoting a greater stress on the groundwater reservoirs. In the years from 2000 to 2030, the Water Table Depth keeps ascending steadily, starting at about 20 m in 2000 and reaching close to 75 m in 2030, thus signifying the drastic decrease in the water stored underground (more depth equals more depletion). Such a pattern points at the continuous extraction of water, as the rate of taking out water is more than the rate of adding water. The same trend can be seen in the case of the Recharge Rate which also declines gradually over the same period. It starts at about 85 units in 2000 and decreases to roughly 48 units by 2030. This dropping off of recharge suggests decreasing natural replenishment which is probably caused by lower rainfall infiltration, loss of permeable surfaces, and shrinkage of water bodies. On the other hand, the Extraction Rate shows a sharp rise, growing from 70 units in 2000 to 200 units in 2030. The steep rise post-2010 points to consumer, agricultural, and industrial demands gaining speed, which parallels the trend of urbanization and

   Climate Change Impact Factor

   Infrastructure Deficit

   Groundwater Depletion

   Urbanization 80

   70

   60

   50

   40

   30

   20

   10

   0

   Temperature Rise

   Rainfall Variability

   Deforestation

   Impact Factor

   Fig.6 Climate Change Impact

   Description of Climate Change Impact Factors

   The radar chart illustrates the relative severity of six major factors contributing to climate-change impacts in the study rea. Each factor is expressed as a percentage severity, representing its influence on environmental and socio-hydrological conditions.

   Hydrological Cycle Disruption

   Increased Evaporation		Atmospheric Moisture

   Intense Rainfall		Surface Runoff

   Flooding		Reduced Recharge

   Fig.7 Hydrological Cycle Distribution

6. DISCUSSIONS

   The relationship between rainfall patterns, flood frequency, and groundwater recharge represents a complex feedback system in Bangalore Rural. Climate change has intensified rainfall variability while urbanization has fundamentally altered natural drainage and infiltration systems.

   Climate Change

   Temperature Rainfall Variability

   Urbanization

   Concretization Lake Encroached

   Combined Effect

   Floods Ground Water

   A detailed study of rainfall patterns, flood occurrences, and groundwater movement in Bangalore Rural indicates that environmental stress is increasing gradually with the factors of rapid urbanization and climate change. Groundwater levels which have been going down gradually over the last twenty years have been mainly affected by the over-extraction of water and low natural recharge, although heavy rains have happened from time to time. On the other hand, floods have happened more often and thus the contradiction between the regions having water scarcity and water surplus is exposed. The above has pointed out the immediate necessity for integrated water resource management which can foster resilience in the long run.

   The research has also pointed out that land use alterationssuch as a decrease in vegetation cover, the draining of wetlands and lakes, a growing urban area, and a shrinking of agricultural landhave been the main causes of a marked decline in the natural recharge capacities. The more the natural surfaces are covered with concrete layers the more runoff there is which eventually leads to flash floods while the groundwater stock continues to decline. Thus, very much land use changes are responsible for the deterioration of water resources and they are also creating a challenge to sustainable development that is rising day by day.

   The socio-economic consequences of these alterations in the water cycle are very serious. The water shortage has caused the household and agricultural expenses to rise, as it has increased the reliance on water tankers and the drilling of deeper borewells. Flood losses cause disruption of infrastructure, health hazards, and the temporary movement of people from their homes. The combined impact of groundwater extraction and flooding keeps the environment under stress and makes it harder for future generations to cope in the case of both rural and peri-urban communities.

   In order to deal with the upcoming crisis, it is crucial to enforce strong policies, involve the community actively, and apply scientific methods in the planning process. It is necessary to give priority to the measures that include large-scale rainwater harvesting, restoration of interconnected lake systems, improvement of green infrastructure, and strict groundwater regulation. The implementation of climate-resilient urban planning models and real-time water monitoring can help to turn the current negative

   trends around and provide the desired level of sustainable water availability. Through the collaboration of the government, scientific institutions, and local communities, Bangalore Rural will be able to shift from crisis management to environmental protection.

7. CONCLUSIONS

   Bangalore Rural district has undergone a considerable change in its hydrological cycle due to climate change, thus making water- related problems such as extreme flooding, groundwater depletion, and water shortages even worse. The variability of rainfall has changed greatly with the long-term average annual rainfall increasing during the past two decades from nearly 880 mm in the early 2000s to more than 1,100 mm by 2024 and a record-breaking tempestuous case of 1,957 mm precipitation in 2022. Nevertheless, these occurrences do not recharge aquifers, instead, they bring heavy runoff and floods pointing to the dwindling infiltration capacity of the area.

   The groundwater data from 2000 to 2024 along with projected values for 2030 expose a dramatic decline in the groundwater resource. The depth of groundwater has varied from 15 meters below the surface in 2000 to roughly 65 meters in 2024 and it is estimated that it will be about 70 meters in 2025 and close to 75 meters in 2030, which sends strong signals of depletion. At the same time, the groundwater recharge has also declined sharply from 85 MCM in 2000 to 55 MCM in 2024 and is likely to dip further to 50 MCM in 2025 and 45 MCM in 2030. In contrast, water withdrawals have multiplied from 70 MCM in 2000 to over 180 MCM in 2024, with a forecast of 190 MCM by 2025 and 200 MCM by 2030. The increasing gap between recharge and extraction is the main cause of the groundwater crisis.

   The contradiction of more rain but less groundwater can be attributed to the direct cause of unsustainable land use changes. Bengaluru Rural has undergone the transformation of built-up areas into natural landscapes at a rapid rate comprising up to 60-70% of green cover reduction and more than 70% of water bodies decline. The turning of the permeable soil to the impervious urban surfaces hinders the natural infiltration, speeds the surface runoff, and raises the occurrence of the destructive flash floods. On top of that, the situation is worsened by the unregulated borewells, the inefficient water infrastructure, and the poor watershed management.

   To sum it up, Bangalore Rural is at a very crucial point where climate change and human activities are putting the water supply at risk for many years to come. If no corrective actions are taken in the short term, the area may be subjected to groundwater depletion, drastic effects on people’s income, and rise in poverty and social unrest during the decade of 2030. Integrated water resource management, lake rejuvenation, rainwater harvesting in rural areas, strict groundwater control and community watershed management are some measures which should be implemented right away. Collaboration among the government, researchers and the community is necessary to reverse the hydrological imbalance and to ensure that the climate resilience needed for a reliable future is

   Water supply and demand statistics

   Climate change has fundamentally altered the hydrological dynamics of Bangalore Rural district, creating a crisis characterized by increased flood frequency, degraded groundwater resources, and heightened water insecurity.

   This study demonstrates that rainfall patterns have become increasingly erratic, with annual precipitation rising from 880mm to over 1,100mm on average, while experiencing extreme variability including record breaking events like the 1,957mm in 2022. Simultaneously, groundwater levels have declined by 333%, from 15 meters in 2000 to 65 meters in 2024, with recharge rates falling by 35%.

   The paradox of increased rainfall coinciding with groundwater depletion underscores the critical role of urbanization in disrupting natural hydrological processes. The 1,028% increase in urban area over 45 years, coupled with 79% loss of water bodies, has transformed permeable landscapes into impervious surfaces that generate rapid runoff rather than ground water recharge

8. CRITICAL FINDINGS
   1. Urbanization (Impact: ~75/100 HIGH)

      Bangalore will have a population of around 14 million by the year 2024; oer 93% of the lakes and forests have been taking up by the built-up area.

      • The rural areas are becoming part of the expanding Bangalore metropolitan area at a fast pace.
      • The peri-urban villages are changing to industrial and residential land.
      • By the year 2029, an additional 15-20% of agricultural land will be eliminated, according to the estimates.
      • There will be more people migrating to Nelamangala, Devanahalli, Doddaballapura, and Hoskote as a result of the increased migration pressure.
      • It is expected that the farming community will have to change their livelihoods to non-agricultural sectors.
   2. Temperature Rise (Impact: ~70/100 HIGH)

      The temperature has already gone up by 0.6°C and it is estimated that the temperature will be around 28.529°C by the year 2029.

      • Heat stress on crops and livestock will be increased.
      • Evapotranspiration will rise by 1015% leading to lesser soil moisture.
      • Dairy cattle production will be less by 8-12% during the hottest period.
      • Sowing & harvest cycles will be interrupted as summers will last longer.
   3. Rainfall Variability (Impact: ~75/100 CRITICAL)

      Karnataka received 38% less rainfall than normal during the NE monsoon and 25% less rainfall than normal during the SW monsoon.

      • The future rainfall range is going to be very unpredictable with 10001900 mm.
      • Drought periods of 23 are foreseen by 2029.
      • Flash floods will become common and soils and vegetation will be adversely affected.
      • Rainfed farms will suffer 30-40% less productivity.
      • Farmers will have to deal with uncertainty regarding seasons which will disrupt their planning.
   4. Deforestation (Impact: ~70/100 HIGH)

      The loss of the green cover has been so drastic that instead of 80% of the land area covered with trees at the beginning of the 20th century, now only less than 4% remains.

      • Water bodies that existed in the area are down to only 1452 from the earlier 193.
      • Deforestation has been projected to cause an additional loss of 58% of the forests due to various infrastructure development.
      • Soil erosion has been increased in the area and this led to the loss of 20 to 30% of the soils fertility.
      • In the areas deforested, the local temperatures are higher by 1 to 2°C.
      • The light and sound of the forest are lost because animals that are not in the area are the ones responsible for pollination. Therefore, reducing crop yield.
   5. Groundwater Depletion (Impact: ~80/100 CRITICAL)

      The depth of the groundwater table has gone up from 15m (2000) to 65m (2024). Further increase to the level of 7280m is expected by 2029.

      The failure of 4050% of the borewells is anticipated.

      The ratio of extraction to recharge is that of 5:1, which is highly unsustainable. The costs of irrigation pumping will rise by 200300%.

      The villages will have to depend on tanker supply for water for 68 months every year.

   6. Infrastructure Deficit (Impact: ~65/100 MODERATE-HIGH)
      • Water supply to rural areas through pipes is still under 60%.
      • Sewage and stormwater management are not sufficient.
      • There are health facilities that cannot cope with heat and waterborne diseases.
      • The number of early-warning and climate forecasting systems is very low.
      • Storage and cold-chain for crops that are very susceptible to climate change are not adequate.
9. URGENT ADAPTATION MEASURES NEEDED

Immediate Actions (20252026)

Rainwater harvesting on a large scale with the establishment of more than 10,000 farm ponds, recharge wells, and check-dams to catch the excess rainwater and increase groundwater recharge.

Changing crop patterns through the replacement of water-intensive crops with drought-resistant varieties such as millets and pulses to the extent that the irrigation needs are reduced.

Micro-irrigation techniques such as drip and sprinkler systems will be expanded to cover 50% of the cultivated land area for the purpose of cutting down on water wastage.

The introduction of agroforestry will involve the planting of more than 5 million trees, thus, soil moisture will be restored, biomass will be increased, and the local micro-climate will be stabilized.

Water of the aquifer will come from the rejuvenation of water bodies and the restoration of more than 500 traditional lakes, tanks, and wetlands will be the focus to increase the natural storage capacity.

Medium-Term Measures (20262029)

Climate-smart agricultural practices and resilient crop breeding for stable yields under changing rainfall conditions.

Strong water governance policies, including strict monitoring and regulation of borewell drilling and groundwater abstraction. Decentralized water infrastructure development, enabling rural water security independent of monsoon fluctuations.

Economic resilience strategies promoting non-farm livelihood opportunities to reduce dependency on climate-impacted agriculture. Advanced climate early-warning systems delivering real-time weather forecasting and advisory services to all farmers.

REFERENCES

1. Central Ground Water Board (CGWB). 2023. South Western Region Bengaluru: Groundwater Report. Ministry of Jal Shakti, Government of India.
2. Kulkarni, T., Gassmann, M., Kulkarni, C. M., & Buerkert, A. 2021. Deep drilling for groundwater in Bengaluru, India: A case study on the citys over-exploited hard-rock aquifer system. Sustainability, 13(21): 12149.
3. Ramachandra, T. V., Shivamurthy, V., & Aithal, B. H. 2018. Frequent floods in Bangalore: Causes and remedial measures. Energy & Wetlands Research Group Technical Report, IISc Bangalore.
4. Tewari, P., Anshu, Dwivedi, S., & Kumar, S. 2023. Increasing frequency of urban floods: Lessons from Bengaluru floods, 2022. Disaster & Development, 12(1), JanuaryJune 2023.
5. Urban groundwater recharge components in Bengaluru. 2022. Taylor & Francis Online Journal Article. (Author unavailable).
6. Atal Bhujal Yojana (ABHY). 2023. National Groundwater Management Improvement Program: Karnataka District Hydrogeological Report. Government of India / Karnataka Ground Water Directorate.
7. Central Ground Water Board. 2024. Dynamic Ground Water Resources of India Karnataka State Report. Ministry of Jal Shakti, Government of India.
8. Kanannavar, P. S., Premanand, B. D., Madolli, M., Gaddanakeri, S. A., & Vijaykumar, C. 2023. Rainwater Harvesting Through Point Recharge Method for Efficient Recharge of Tube Wells for Sustainable Management of Groundwater Resources in Karnataka. International Journal of Environment and Climate Change, 13(5):46-52.
9. Konda, G., Chowdary, J. S., Gnanaseelan, C., Vissa, N. K., & Parekh, A. 2024. Temporal and Spatial Aggregation of Rainfall Extremes Over India Under Anthropogenic Warming. Scientific Reports.
10. Kulkarni, T., Gassmann, M., Kulkarni, C. M., Khed, V., & Buerkert, A. 2021. Deep Drilling for Groundwater in Bengaluru, India: A Case Study on the Citys

    Over-Exploited Hard-Rock Aquifer System. Sustainability, 13(21):12149.

11. Mondal, A., Kundu, S., & Mukhopadhyay, A. 2012. Rainfall Variability Analysis Using Mann-Kendall Test: A Case Study. International Journal of Geology, Earth and Environmental Sciences.
12. Sridhara, S., Gopakkali, P., & Nandini, R. 2020. Trend Analysis of Precipitation and Temperature Over Different Districts of Karnataka: An Aid to Climate Change Detection and Cropping System Option. International Journal of Environment and Climate Change, 10(3):15-25.
13. Tewari, P., Anshu, Dwivedi, S., & Kumar, S. 2023. Increasing Frequency of Urban Floods: Lessons from Bengaluru Floods, 2022. Disaster & Development, 12(01).
14. Varghese, S. J., et al. 2025. Changes in Physical Characteristics of Extreme Rainfall Events During the Indian Summer Monsoon Based on Downscaled and

    Bias-Corrected CMIP6 Models. Scientific Reports.

15. India Meteorological Department (IMD). 2022. Annual Report 2022. Government of India.
16. Ramachandra, T. V., Shivamurthy, V., & Aithal, B. H. 2018. Frequent Floods in Bangalore: Causes and Remedial Measures. Energy & Wetlands Research Group, IISc Bangalore Technical Report.
17. Gowda, B. R., & Ramu, M. 2021. Assessment of Spatio-Temporal Variations of Groundwater Levels in Bengaluru Region. International Journal of Water Resources and Environmental Engineering, 13(2): 47-58.
18. Ramesh, H., Swathi, R., & Sridhar, V. 2020. Hydro-Climatic Trend Analysis Using Parametric and Non-Parametric Methods in Southern India. Journal of Hydrologic Engineering, 25(3).
19. Mahesha, A., & Singh, S. 2022. Impact of Urbanization on Flood Risk and Drainage in Bengaluru Metropolitan Region. International Journal of River Basin Management, 20(4): 521-533.
20. Srinivas, V., & Nataraju, L. 2024. Climate Variability and Groundwater Stress in Semi-Arid Hard-Rock Terrain of Karnataka. International Journal of Hydrology Science and Technology, 14(1): 66-80.