Abstract

The increasingly available soil moisture sensor networks around the world provide a more comprehensive approach to study catchment hydrology. In the Shale Hills Critical Zone Observatory (CZO), a 7.9-ha forested catchment with steep hillslopes and different soil types, a sensor network with 35 automatic monitoring sites spreading across the entire catchment has been operated since 2011. At each site, soil moisture sensors were installed in various soil horizons from the surface to the soil-bedrock interface to measure soil moisture and temperature at the 10-min interval. Based on the continuous, high-frequency soil moisture monitoring data, we conducted a series of analyses to characterize the hydrologic behavior of the Shale Hills catchment at various temporal scales. (1) In the first several hours after storms, different flow types, such as vertical preferential infiltration and subsurface lateral flow, as well as their spatial distribution were identified. (2) At the event scale, information on the response time and dynamics of soil moisture to storms, changes in soil water storage, the wetting front movement and wetting depth, and the drainage process was determined at each site, which revealed a higher hydrologic connectivity in swales that acted as the primary route in the subsurface to direct stormflow from the hillslope to the valley. (3) At the seasonal scale, distinct cycles of wetting and drying in soil moisture were detected, which demonstrated the influence of vegetation distribution and growth, snow melting, and different soil-terrain attributes on the spatial pattern and temporal evolution of soil moisture. (4) At the inter-annual scale, the enriched soil moisture information shed new light on the temporal stability of the spatial variability of soil moisture across the catchment that was not identified by manual TDR measurements repeated in every several weeks. (5) Long-term monitoring over the years reflected the trends and variability of soil climate (soil moisture and soil temperature) and its interaction with the changing climate in the atmosphere. Standardized sensor network design, data collection, and data analysis are advocated to enhance the cross-catchment comparison to extend the application of a sensor network to advance the understanding of catchment hydrology.

Citation

Li Guo*, Henry Lin (2018): Soil Moisture Sensor Network Advances the Monitoring and Understanding of Catchment Hydrology: Case Studies from the Shale Hills CZO. Abstract H53J-1721 presented at 2018 AGU Fall Meeting, Washington, D.C., 10-14 Dec.

This Paper/Book acknowledges NSF CZO grant support.