Agricultural drainage ditch network extraction and its application in agroecosystem modeling

Abstract:

Drainage ditches play an important role in the hydrological and biogeochemical cycles of agricultural ecosystems. However, water and nutrient transport in the ditch network is not fully represented in the current hydrological models or ecosystem models. One reason is the lack of accurate information about the location and topological connection of ditch networks. In this study, we proposed a remote-sensing-based method to extract the ditch network efficiently and developed a water-nutrient ditch routing module and coupled it with an advanced agroecosystem model, ecosys. We used Common Land Unit (CLU) datasets to generate initially guessed ditch networks and refined the initial ditch network by classifying high-resolution DEM pixels into ditch cells and non-ditch cells using the thresholds of gradient and diffusion. Then, we implemented different routing algorithms (i.e. Muskingum, Muskingum-Cunge) using the generated ditch network to assess the impacts of agricultural drainage ditch network on water and nutrient transport at the watershed scale. Routing results from the ditch-based methods were compared with those from traditional non-ditch-based routing methods. We conducted our demonstration study at a HUC8 watershed, Spoon River basin, in east-central Illinois, USA. Our results highlight the critical role of the agricultural drainage ditch network in delivering water and nutrients from individual fields to watersheds.