Understanding Saul Kere: A Lake, a Watershed and a Forgotten Water System

 Understanding Saul Kere: A Lake, a Watershed and a Forgotten Water System

The story of Saul Kere is not simply the story of a lake. It is the story of an entire landscape—and what happens when the natural pathways through which water has moved for generations are gradually forgotten, altered or obstructed.

Saul Kere: More Than a Waterbody

In the rapidly urbanising landscape of Bengaluru, lakes are often viewed as isolated waterbodies: a blue patch on a map, a recreational space, a piece of open land or, increasingly, a site for infrastructure.

But a lake is never just a lake.

Every lake exists within a larger system of slopes, valleys, streams, drains, wetlands, catchments and downstream waterbodies. Water does not recognise property boundaries, roads, layouts or municipal jurisdictions. It follows gravity and topography.

Saul Kere is a powerful example of this relationship.

To understand the lake—and particularly the flooding that affected the surrounding areas during the intense rains of September 2022—we need to look beyond its visible water spread. We need to understand the architecture of the landscape around it.

The Forgotten Architecture of Bengaluru’s Lakes

Bengaluru’s traditional lakes were part of an interconnected cascading tank system.

Water from higher elevations flowed into one lake. When that lake reached capacity, excess water moved through a waste weir or drain into downstream areas and eventually into another lake.

This was not accidental.

The system was shaped by the natural topography of the land and, over time, supported irrigation, groundwater recharge and the movement of stormwater across the landscape.

Saul Kere sits within this larger hydrological system.

Historically, its relationship with surrounding lakes—including Kaikondrahalli, Bellandur and other waterbodies within the watershed—was determined by the natural direction of water flow.

Today, however, the landscape through which this water moves has changed dramatically.

Roads, layouts, buildings, infrastructure and other urban development have altered the relationship between water, land and drainage.

The result is a fundamental question that needs to be asked whenever flooding occurs:

Has the water suddenly become the problem, or have the pathways through which it historically moved been gradually removed, narrowed or forgotten?

 

Looking Back: Saul Kere in 2002

Historical satellite imagery provides an important window into how the landscape around Saul Kere has changed.

The presentation documents the Saul Kere area as it appeared in 2002, including its approximate command area and the surrounding landscape.

At that time, the downstream relationship between the lake and its drainage system was clearer.

Two important outlets could be identified downstream of Saul Kere.

One was the waste weir outlet, located towards the north-western corner of the lake. The other was a sluice gate outlet, originating from the northern side of the lake bund.

These were not minor features.

The downstream channels associated with these outlets were approximately 29 feet wide in the satellite imagery—comparable in width to a major primary stormwater drain.

The existence of the sluice gate also tells us something important about the historical function of the lake.

Saul Kere was not simply designed to hold water indefinitely. Water could be released downstream into the command area for irrigation.

The lake therefore had a hydraulic relationship with the land beyond its bund.

 

A Changing Landscape

When the same area is examined in more recent satellite imagery, an important change becomes visible.

The waste weir outlet continues to function.

However, the historical sluice gate outlet and its downstream drainage pathway are no longer visible in the same form.

This represents more than the disappearance of a physical structure.

It represents the loss of a pathway through which water was historically managed.

When a lake’s natural or engineered outlets are altered, removed or disconnected from their downstream systems, the consequences do not necessarily become visible immediately.

During ordinary rainfall, the system may appear to function.

But intense rainfall places an entirely different demand on the landscape.

Large volumes of water arrive within a short period. The lake fills. Drains carry increasing flows. Bottlenecks become critical.

At that point, every missing outlet, narrowed drain, raised downstream surface and blocked channel can become part of a much larger problem.

 

 

Understanding the Saul Kere Watershed

The visible lake is only one part of the system.

The larger story begins with its watershed.

A watershed is the area of land from which rainfall ultimately drains towards a common low point or waterbody.

The watershed associated with Saul Kere extends far beyond the lake itself.

Using elevation data and natural drainage patterns, the presentation maps the network of flows that converge towards the lake.

The maps reveal something that is not immediately visible when standing at the edge of Saul Kere: a complex network of natural drainage pathways extends across the surrounding landscape.

Small flows join larger flows.

Neighbourhoods that may appear disconnected on the ground can nevertheless be connected hydrologically.

Rain falling kilometres away can eventually influence the amount of water arriving at Saul Kere.

This is why planning for a lake cannot be confined to the lake boundary.

The catchment matters.

The upstream lakes matter.

The drains matter.

The slopes matter.

And the downstream pathways matter.

  

 

A Large and Increasingly Urban Watershed

The spatial analysis in the presentation estimates the Saul Kere watershed at approximately 23.67 square kilometres, or nearly 2,367 hectares.

The lake itself occupies only a fraction of this larger area.

The watershed is divided broadly into two sides, together covering more than 23 square kilometres.

What is particularly significant is the extent of urbanisation within this watershed.

Large portions of the land that historically allowed rainfall to infiltrate into the ground have been transformed into built-up surfaces.

Roads, buildings, paved areas and other hard surfaces change the way rainfall behaves.

On natural or vegetated land, a portion of rainfall infiltrates into the soil.

In an urban landscape, a much larger proportion becomes surface runoff.

And that runoff needs somewhere to go.

During intense rainfall, the difference can be dramatic.

A watershed that once absorbed and slowed water increasingly becomes a system that rapidly directs large volumes of runoff towards low-lying areas and drainage channels.

The Saul Kere watershed also receives flows associated with numerous upstream lakes. The analysis identifies approximately 13 lakes within the broader drainage context.

This means that Saul Kere must be understood not as an isolated basin but as part of a larger and interconnected hydrological network.

 

Inlets, Outlets and the Natural Logic of Water

One of the most important ways to understand Saul Kere is to compare its current inlets and outlets with the natural drainage patterns identified through elevation data.

The lake receives water through multiple inlets.

Historically and naturally, water also required clear pathways to leave the lake.

The natural drainage analysis reveals the logic of these connections.

Water flows downhill.

Where the landscape creates a natural valley, water accumulates.

Where multiple flows converge, the volume of water increases.

A lake acts as a storage point within this system—but it is also a transition point.

If the inflow is larger than the available storage, water must move downstream.

This simple principle is central to understanding urban flooding.

A lake cannot be treated as a closed container.

Its safety depends not only on how much water it can hold but also on whether its inlets and outlets function as part of an integrated system.

The disappearance or alteration of one drainage pathway can place greater pressure on another.

The narrowing of a downstream drain can create a bottleneck.

Raising the elevation of downstream land can prevent water from moving naturally.

And an obstruction at a critical point can cause water to accumulate upstream, often in places where people least expect it.

What the Maps Do—and Do Not—Show

An additional challenge in understanding urban water systems is the difference between the physical landscape and the administrative records used to describe it.

The presentation highlights areas downstream of Saul Kere where historical drainage pathways are not clearly represented in available mapping.

For example, some records show portions of the lake or surrounding land differently from the natural drainage patterns visible through topographical analysis.

Similarly, the Revised Master Plan identifies parts of the downstream area as ecologically sensitive, yet certain historical or natural drainage pathways are not clearly represented as stormwater drains.

This creates an important planning problem.

If a drain disappears from the map, the water does not necessarily disappear from the landscape.

During dry weather, the absence of an obvious water channel may appear insignificant.

During intense rainfall, however, water may attempt to reclaim the same low-lying pathways through which it historically flowed.

Understanding a lake therefore requires bringing together multiple perspectives:

• Historical satellite imagery
• Topographical and elevation data
• Natural drainage patterns
• Existing stormwater infrastructure
• Land-use changes
• Field observations
• Historical records and local knowledge

No single map can tell the entire story.

 

  

 

Saul Kere and the Floods of September 2022

The severe rainfall and flooding of September 2022 brought the weaknesses of Bengaluru’s urban water systems into sharp focus.

Saul Kere was identified as one of the locations where flooding extended into major surrounding roads and urban areas.

Following the flooding, a field survey was conducted around the lake and its downstream drainage system to better understand the existing conditions and identify possible interventions.

The observations point towards a combination of interconnected issues rather than a single cause.

Among the concerns identified were:

• Bottlenecks in the lake’s downstream outlet system.
• Possible choking of drains due to solid waste.
• Changes in the elevation of downstream areas.
• Narrowing of downstream drainage pathways.
• The absence of adequate drainage connections in parts of the surrounding system.
• Increased runoff resulting from urbanisation.
• Greater pressure on drainage infrastructure during intense rainfall.

These issues reinforce an important point:

Flooding is rarely caused by one lake, one drain or one event.

It is usually the result of multiple failures across an interconnected system.

A narrowed drain upstream may combine with a blocked culvert downstream.

An increased volume of runoff may meet an outlet designed for a very different landscape.

A historical drainage pathway may have been interrupted.

Together, these changes can transform an extreme rainfall event into a major urban flood.

 

Can Bigger Drains Alone Solve the Problem?

One of the immediate responses to flooding is often to increase the size of drains.

This may be necessary at identified choke points.

The presentation notes proposals to expand critical bottlenecks in the drainage network, including areas near NR Layout Road and the Outer Ring Road service road.

But there is a larger question that must be answered before assuming that widening drains alone will solve the problem.

How much water is actually entering the system?

The answer depends on:

• The total size of the watershed.
• The amount and intensity of rainfall.
• The extent of urbanisation.
• The amount of paved and impervious surface.
• The capacity of upstream lakes.
• The storage capacity of Saul Kere.
• The capacity of downstream drains.
• The condition of existing outlets.
• Changes in land elevation and drainage pathways.

Without understanding the complete volume of runoff generated across the watershed, infrastructure improvements may simply move the bottleneck from one location to another.

A larger drain may carry water faster to the next obstruction.

A widened channel may reduce flooding locally while increasing pressure downstream.

This is why the presentation recommends a more comprehensive approach based on runoff calculations and flood modelling.

Flood modelling can help answer critical questions:

How much water enters the Saul Kere system during different rainfall scenarios?

How much water can the lake safely retain?

How quickly must excess water be released?

Where are the critical bottlenecks?

What happens when multiple upstream lakes are full?

How will increasing urbanisation affect future runoff?

And perhaps most importantly:

Will proposed interventions continue to work as rainfall patterns and land use change?

The Lake as Flood Infrastructure

One of the most important ways to rethink urban lakes is to recognise that they are part of the city’s flood-management infrastructure.

A healthy lake does more than hold water.

It can temporarily store stormwater.

It can slow the movement of water.

It can allow infiltration and groundwater recharge.

It can reduce the immediate pressure on downstream drainage systems.

But for a lake to perform these functions, it must be treated as part of an entire watershed.

Its capacity cannot be assessed independently of its inlets and outlets.

Its restoration cannot stop at the bund.

Its management cannot ignore upstream development.

And its flood-management role cannot be separated from the downstream landscape.

The presentation suggests the need to understand how much water Saul Kere can retain and how the lake can be managed before and during the monsoon.

This raises the possibility of more dynamic water management.

If lakes are already full before an extreme rainfall event, their ability to absorb additional runoff is reduced.

Monitoring water levels and understanding forecast rainfall could help inform decisions about controlled releases where appropriate and technically feasible.

Such interventions, however, need to be based on careful hydrological modelling rather than ad hoc responses.

 

Before We Alter the Lake, We Need to Understand It

The presentation also raises an important caution regarding interventions such as desilting.

Desilting is often seen as an obvious solution for increasing lake capacity.

But altering the bed of a lake without understanding the condition of its bunds, hydrology and downstream infrastructure can create new risks.

If additional storage capacity is created but the downstream system remains constrained, the fundamental drainage problem may remain unresolved.

Similarly, if water levels and pressures change without understanding the structural condition of the bund, safety concerns may arise.

This does not mean that desilting should never be undertaken.

It means that it should be part of a comprehensive hydrological and engineering assessment.

The lake cannot be treated as an isolated construction project.

Every intervention needs to be evaluated within the context of the larger water system.

 

Saul Kere Is Also a Living Ecosystem

The discussion around Saul Kere cannot be limited to hydrology and flooding.

The lake is also an important ecological space.

The biodiversity observations presented in the study record more than 205 species of birds, including migratory species, along with more than 517 recorded species of insects and animals.

These numbers remind us that Saul Kere is not simply an empty water-storage basin.

It is habitat.

It is part of a larger ecological network.

The edges of the lake, the water, vegetation, shallow areas and surrounding open spaces together support a diverse range of life.

This ecological value is closely connected to the lake’s physical and hydrological character.

When lakes are excessively concretised, their edges hardened or their natural surroundings replaced entirely by infrastructure, the ecological functions of the landscape can be compromised.

The challenge is therefore not simply to manage water as quickly as possible.

It is to design interventions that recognise the multiple roles played by an urban lake.

Saul Kere is simultaneously:

• A water-storage system.
• A flood-mitigation asset.
• A component of a larger drainage network.
• A groundwater recharge opportunity.
• A habitat for birds and other wildlife.
• An ecological space within a densely urbanised region.

 

 

Relearning the Landscape

The story of Saul Kere offers a broader lesson for Bengaluru.

For decades, the city has expanded rapidly.

The landscape has changed faster than our understanding of the systems beneath it.

Streams have become drains.

Drains have been narrowed or redirected.

Valleys have become roads and layouts.

Open land has become impermeable surfaces.

Lakes that once formed part of an irrigation network have become surrounded by dense urban development.

But water continues to follow the underlying geography.

The natural drainage system does not disappear simply because it is no longer visible on the surface.

This is why understanding the past is essential to planning the future.

Historical satellite imagery can show where water once flowed.

Elevation data can reveal the natural structure of the watershed.

Field surveys can identify present-day bottlenecks.

Flood modelling can help anticipate future risks.

Together, these tools can help us move away from reactive responses towards a more informed understanding of urban water.

 

What Should Happen Next?

The findings from the study suggest that the future of Saul Kere should be approached through a watershed-wide strategy.

Some of the key areas that require further investigation include:

1. Comprehensive flood modelling

The entire Saul Kere watershed needs to be modelled to understand how water behaves under different rainfall intensities and future urbanisation scenarios.

2. Calculation of total runoff

The amount of stormwater generated across the watershed should be estimated, particularly in light of the increasing proportion of built-up and paved land.

3. Identification and restoration of critical drainage pathways

Historical and natural drainage routes should be studied alongside existing infrastructure to identify where water movement has been interrupted or constrained.

4. Investigation of choke points

Critical bottlenecks in the downstream system should be examined not only individually but as part of the complete drainage network.

5. Understanding lake storage capacity

The amount of water that Saul Kere can safely retain needs to be assessed in relation to expected inflows and downstream capacity.

6. Monitoring upstream lakes

The interaction between Saul Kere and upstream lakes needs closer study, particularly during periods of intense rainfall.

7. Careful assessment before major physical interventions

Any work involving desilting, modification of the lake bed, bund or outlets should be preceded by detailed hydrological and engineering assessment.

8. Protection of ecological value

Flood-management interventions should also consider the lake’s biodiversity and ecological role.

 

A Lake Cannot Be Understood in Isolation

Perhaps the most important lesson from Saul Kere is this:

A lake boundary is not the boundary of a lake’s influence.

The water that enters Saul Kere may have travelled across kilometres of urban landscape.

The water leaving it may affect roads, neighbourhoods, drains and downstream lakes.

The biodiversity of the lake depends on conditions beyond the visible waterbody.

And the risk of flooding depends on decisions made throughout the watershed.

This means that protecting Saul Kere requires more than beautifying its edge or strengthening its bund.

It requires understanding its architecture.

The architecture of the watershed.

The architecture of the natural drainage network.

The architecture of the historical tank system.

And the architecture of the modern city that has grown around it.

Saul Kere is not simply a lake waiting to be engineered.

It is a living part of Bengaluru’s water system.

Before we decide how to intervene in it, we must first understand how that system works.

Only then can solutions address not just the visible symptoms—flooding, overflowing drains or waterlogged roads—but the deeper changes that have taken place across the landscape.

Because in the end, water is not an intruder in this landscape.

It has always belonged here.

The real challenge is whether our cities still remember where it is supposed to go.