Project Details
Projekt
Improved soil moisture and biomass quantification through combination of ground-based neutron and LiDAR sensing and modeling
Applicants
Dr. Heye Bogena; Professor Dr. Johan Huisman
Subject Area
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 357874777
In the first phase of the research unit Cosmic Sense, we focused on field experiments combining cosmic ray neutron probes with extensive measurements using in-situ sensors and rover campaigns with the Jülich cosmic rover. We found that aboveground biomass can be inferred using the ratio of thermal to epithermal neutrons in the case of sugar beet. However, evaluation of campaigns for wheat and maize provided less conclusive results suggesting that the measured thermal neutron signal is influenced by vegetation structure. Therefore, we assessed the footprint characteristics of the thermal neutron signal using Monte Carlo simulations with the neutron transport model URANOS. In the second phase, we will expand the investigations on improved soil moisture and biomass quantification. We will make use of data from 15 new CRNS stations operated at agricultural sites to investigate how biomass affects the thermal and epithermal neutron signal. At selected sites, continuous vegetation height measurements with three ground-based 3D LiDAR systems and occasional campaigns with a LiDAR-equipped drone will be carried out in cooperation with the research modules SD and RS to obtain detailed information on the spatial and temporal variation of biomass. The field experiments will be modeled using the process-based land surface model CLM5 to generate continuous time series of soil moisture profiles and biomass. In addition, we will investigate how the thermal neutron signal is affected by soil chemistry, aboveground biomass, as well as plant structure using dedicated model experiments with URANOS together with the research module NS. We will also test a newly developed neutron detector device developed within the RM DD that allows measurements at additional energy levels. The experimental and modeling data as well as the gained physical process understanding will be used to develop methods to estimate biomass as well as to correct soil moisture using appropriate simplifications.
DFG Programme
Research Units
