How to Stabilize Hills and Creek Bottoms

Updated: Jan 10

Because of erosion, hills and creek bottoms can often destabilize and shift. Fortunately, erosion control methods, such as Flexamat installation, can prevent this. These systems act as a tight container for the existing topological structure, helping it to endure erosive forces.




The Stabilizing Process


Hills and creek bottoms are at risk of degradation, erosion and shifting over time. Hill erosion comes in the form of degradation and loss of soil particles. Heavy run-off after storms and wind can drain the structure of the material required for its function (such as a flood defense barrier or raised embankment alongside the highway). Over time, the hill loses mass and, eventually, height and performance.


Creeks erode for similar reasons. However, the pace of degradation is often faster. Friction of running water – particularly during flood peak conditions – strips banks of loose or soluble particles. This process can lead to a loss of surrounding vegetation and property damage.


Flexamat is a technology that permits permanent erosion control for at-risk topologies, such as hills and creeks. Unlike many solutions, it works with nature.


The articulated concrete block mat comprises blocks of concrete interspersed with a high-strength geogrid. Projects can use it raw or in combination with reeds, grasses and other plants commonly found on hillocks and beside creeks.


Flexamat stabilizes topologies by containing material and protecting it from erosion. Hills and creeks eventually erode away or change their position. However, with Flexamat erosion control in place, this no longer occurs at the same rate. The system protects loose particles from passing air and water currents, allowing these landscape features to persist longer than they otherwise would.


Stabilization For Creeks


To stabilize a creek, engineers first arrive on site and assess whether erosion is present. They must then contact local government agencies to collect any permits required.


After that, they select the correct Flexamat product to install. Solutions are available for applications parallel to flow, perpendicular to flow, and for particularly steep riverbanks.


Laying requires:


  1. Ensuring that the riverbank is stable and free from debris (rocks, roots, etc.)

  2. Fertilizing the existing ground with subgrade specific mix (such as native grasses)

  3. Installing Flexamat according to the steepness of the bank, using U-anchors installed in 2-foot increments to hold it in place

  4. Embedding the mat 24-inches beyond the anticipated scour point in a termination trench. Engineers should fill the trench with suitable aggregate


Stabilizing For Hills


There are also a range of Flexamat products for hill stabilization. These include Flexamat Standard and Plus.


Laying Flexamat slope armoring requires:


  1. Preparing the subgrade, ensuring that it is free from rocks, roots and other debris

  2. Fertilizing the ground with appropriate subgrade, before the installation

  3. Laying the mat and then extending it beyond the crest of the slope

  4. Installing the appropriate rebar and 18-inch U-anchors in 2-foot increments

  5. Filling and compacting the termination trench


Why Erosion Control Is So Vital


Topsoil is highly susceptible to erosion and natural processes. Passing wind and water strips away loose stone and sediment over the decades. For instance, Egypt’s Nile River has migrated several miles since ancient times. (Archaeologists believe that the pyramids of Giza were once on its banks but they are now some distance into the desert).


This same process is occurring in all unstabilized hills. Gravity, wind and rainfall all combine. In fact, soil erosion occurs much more rapidly on hills than it does on conventional ground.


Soil erosion is a significant environmental issue. Estimates suggest that the average plot of land loses around 1 percent each year. Poor land management, climate change and agricultural activities are all partially to blame.


Without erosion control, this process may continue unmitigated. Eventually, the world’s most productive topsoil could be lost to the ocean, making it challenging to raise healthy crops. Degradation reduces ecosystem diversity and can lead to desertification under certain conditions.


More specifically, erosion control helps in a variety of situations closer to home. Geotextiles, articulated concrete blocks and Flexamat can prevent:


  • Gullies from forming in sloped areas

  • Collapse of hillocks constructed for infrastructural purposes (such as roads or flood defences)

  • Exposed tree roots from forming

  • Silt from forming to the point where it kills off marine wildlife


In many cases, solutions like Flexamat, are critical for ecological maintenance. Controlling erosion allows developers to define the incline of a slope, sun and shade levels, soil quality and irrigation. Without such systems in place, topsoil is much less likely to remain intact, eventually leading to degradation that affects function.


If you would like to learn more about hill and creek stabilization, please speak with a Flexamat representative today.