Managing ditches for agroecological engineering of landscape. A review

Abstract

Agriculture must now feed the planet with the lowest environmental impact. Landscape management is a means to protect natural resources from the adverse impacts. In particular, the adequate management of ditches could improve crop quality. Here, we review ditch design and maintenance. We found the following major points: (1) ditch networks have been primarily designed for waterlogging control and erosion prevention. Nonetheless, when properly managed, farm ditches provide other important ecosystem services, namely groundwater recharge, flood attenuation, water purification, or biodiversity conservation. (2) All ditch ecosystem services depend on many geochemical, geophysical, and biological processes, whose occurrence and intensity vary largely with ditch characteristics. (3) The major ruling characteristics are vegetative cover; ditch morphology; slope orientation; reach connections such as piped sections and weirs, soil, sediment and litter properties, biota, and biofilms; and network topology. (4) Ditch maintenance is an efficient engineering tool to optimize ecosystem services because several ditch characteristics change widely with ditch maintenance. For instance, maintenance operations, dredging, chemical weeding, and burning improve waterlogging and soil erosion control, but they are negative for biodiversity conservation. Mowing has low adverse effects on biodiversity conservation and water purification when mowing is performed at an adequate season. The effects of burning have been poorly investigated.

Artificial Aquatic Ecosystems

“…The reduced physical complexity of many artificial aquatic systems, such as concrete-lined channels, obviously limits their value as habitat and potential for improvements in water quality [126]. Restorations that seek to improve these values therefore often focus on the (re-) introduction of heterogeneous structures that are more similar to natural systems [120].…”

“…In ditches, management strategies, including dredging, mowing, chemical weeding, burning, and regulation of water depth, can have significant impacts on ditch biodiversity and water quality [137,138]. However, ongoing management and maintenance, like initial design, often does not include these potential outcomes in its considerations, instead opting to continue to focus on relatively few, highly human-oriented goals [126]. Such decisions about ongoing management and policy, however, can, at least, in theory, be revised to reflect changing goals.…”

From 3D grassy vegetation point cloud to hydraulic resistance: Application to close‐range estimation of Manning coefficients for intermittent open channels

“…As a consequence, the vegetation of intermittent open channels and its dynamics could provide numerous ecosystem disservices and services (Dollinger, Dagés, Bailly, Lagacherie, & Voltz, 2015) by affecting the former channel hydraulic conveyance capacities, by trapping and transporting sediments, nutrients, and pollutants, making them biogeochemicals hot spots in addition to be ecological hot spots (Herzon & Helenius, 2008).…”

Vegetated canals mitigate nitrogen surplus in agricultural watersheds

“…nutrient cycling, biodiversity, habitat, water depuration) is generally not considered in the current management practices (Herzon and Helenius, 2008;Pierce et al, 2012;Dollinger et al, 2015). This contrasts with the Millennium Ecosystem Assessment (2005), which aims at identifying, protecting and restoring multiple services provided by ecosystems, including agricultural ones.…”