Erosion Risk for Agricultural Land in the Upper Assiniboine River Conservation District, Manitoba, Canada

EROSION RISK AREAS

(Click on the map for a full-size version or on the link below for a more detailed pdf.)

A disclaimer: The data used for this project is fictional, intended only to show a process, nothing more.

Erosion risk is influenced by a number of factors. Slope is a factor – water moves downhill, taking soil/sediment with it. Proximity to a river (or any water body) is a factor, since water erodes away the land at its edges unless protected by vegetation, which holds the soil down. And the way land is used is also a factor.  Agricultural processes such as tillage often leave soil exposed to the elements and more vulnerable to erosion, given the right conditions, but healthy crops or other plants growing in soil keep it from eroding. Soil make-up is important: soil that is sandy will let go of water quickly (making it vulnerable to water erosion), which keeps the soil dry (making it vulnerable to wind erosion), but clay soils hold onto water. For producers, it is important to manage the erosion potential of their topsoil, because that has a direct impact on their land’s productivity, and ultimately their bottom line.

One more explanation: a Conservation District in Manitoba is a group that works alongside of the Manitoba government to help locals plan and implement water management programs on both a technical and financial level (http://mcda.ca).

In order to isolate the most severe areas of erosion risk for agricultural land, the process is first to identify the land that is used for agriculture in this district (through the use of land use maps). The digital elevation model (DEM) that is the backdrop for this map contains slope information; we identify the areas that have both high and severe slopes. The soil data will show what soils have sandier textures and are therefore more vulnerable to erosion. We can easily see where the Assiniboine River and its tributaries are, and what land lies adjacent to them.

In identifying geographical regions using GIS technology, what we essentially do is create “layers” of data with individual characteristics and then put them on top of each other to create a layer that has all the characteristics in common. In this fictional example, the areas that are used for agriculture, have a high to severe slope, have erodible soils, and lie in close proximity to water are shown on the map.