5 Signs a Critical Slope May Need Dedicated Monitoring

The monitoring requirements of a slope often evolve throughout its lifecycle. Changes in geometry, groundwater conditions, loading, weather events, or operational activities can alter the level of uncertainty associated with slope performance.

While routine inspections remain an important part of geotechnical practice, there are situations where additional monitoring can provide valuable insight into how a slope is behaving over time.

Not every slope requires continuous monitoring. However, understanding the indicators that warrant closer observation can help geotechnical engineers make informed decisions, reduce uncertainty, and improve risk management outcomes.

The following signs can help identify when a critical slope may benefit from dedicated monitoring.

1. Cracks Are Appearing or Expanding

One of the most common indicators of changing slope behaviour is the appearance of tension cracks.

These cracks often form near the crest of a slope as the ground begins to deform and pull apart. While some cracking may be superficial, widening or lengthening cracks can indicate that a larger mass of material is responding to changing conditions.

The challenge is that visual observations alone rarely provide enough information to determine whether movement is active, accelerating, or stabilising. Dedicated monitoring systems can measure displacement over time, helping engineers distinguish between seasonal surface changes and more significant deformation trends.

If cracks are appearing where none existed before, or existing cracks are growing, it may be time to consider continuous monitoring.

2. Water Conditions Have Changed

Water is one of the most influential factors affecting slope stability.

Heavy rainfall, blocked drainage systems, rising groundwater pressures, leaking infrastructure, and poor surface water management can all alter the behaviour of a slope. Even slopes that have remained stable for years can respond differently when water conditions change.

In many cases, changes in groundwater or surface water conditions occur gradually, making them difficult to assess through inspections alone. Dedicated monitoring can help determine whether a slope is responding to those conditions and how that response is evolving over time.

Where water conditions have changed significantly, additional monitoring often provides valuable context for geotechnical decision-making.

3. The Consequences of Failure Are Increasing

The need for monitoring is not determined solely by the likelihood of movement. Consequence also plays an important role.

A slope located in a remote area may present a very different risk profile from one situated above a haul road, tailings storage facility, railway, processing plant, public roadway, or critical infrastructure.

As the consequences associated with slope performance increase, so does the value of objective monitoring data. Dedicated monitoring can provide engineers and asset owners with greater confidence when making operational, maintenance, and risk management decisions.

In many cases, monitoring is as much about reducing uncertainty as it is about detecting movement.

4. Traditional Inspections Are No Longer Providing Enough Information

Routine inspections, survey measurements, and geotechnical assessments remain valuable components of any monitoring program. However, there are situations where they may not provide the level of detail required.

Movement can occur between survey campaigns. Changes may develop over hours or days that are difficult to capture through periodic inspections alone.

Modern slope monitoring technologies provide continuous measurements across an entire slope surface rather than relying on a limited number of monitoring points. This allows engineers to understand not only whether movement is occurring, but also where it is occurring and how it is changing over time.

If routine inspections are raising questions that existing monitoring methods cannot answer, dedicated monitoring may provide the additional insight required.

5. Small Movements Have Already Been Detected

One of the most valuable applications of dedicated monitoring is understanding small movements before they become larger trends.

Early-stage deformation is often measured in millimetres rather than metres. While these movements may not be visible to the naked eye, they can provide important information about how a slope is responding to environmental conditions, excavation activities, groundwater changes, or operational factors.

Monitoring enables engineers to evaluate questions such as:

• Is the movement ongoing?
• Is it accelerating or slowing?
• Is it linked to rainfall or operational activities?
• Is it occurring across a broad area or within a specific zone?

Small movements do not always indicate a significant problem. However, when measured consistently over time, they can reveal trends that may otherwise go unnoticed. Understanding whether deformation is accelerating, stabilising, or responding to site conditions often provides valuable context for future decision-making.

Monitoring as a Tool for Better Decision-Making

Dedicated slope monitoring is not simply about detecting failure. Its primary value lies in improving understanding of slope behaviour.

When indicators such as cracking, changing water conditions, increasing consequences, limitations in traditional inspections, or measurable deformation begin to emerge, monitoring can provide the objective data needed to support informed decisions.

Modern deformation monitoring technologies are making continuous monitoring more accessible across mining operations, tailings storage facilities, waste dumps, landslide-prone areas, and civil infrastructure projects. By detecting and measuring movement earlier, geotechnical teams can better understand changing conditions, reduce uncertainty, and respond with greater confidence.

Learn More

Considering dedicated slope monitoring?

NanoRadar provides continuous deformation monitoring with sub-millimetre precision, helping geotechnical teams track movement, identify trends, and better understand slope behaviour before small changes become larger concerns.

Designed for applications including mine slopes, tailings dams, waste dumps, landslides, and underground mining environments, NanoRadar delivers near real-time monitoring in a compact and rugged form factor.