Monitoring Drought From Short-Term Soil Moisture Records: An Upper Missouri River Basin Case Study

Historical observations of in situ soil moisture conditions have generally been limited both spatially and temporally. This has made it challenging to place soil moisture observations into a historical context, and utilize these measures in drought monitoring applications. However, there may be opportunities to take advantage of the recent increase in soil moisture monitoring networks by placing observations into a soil characteristic context. Since the accessibility of water to plants from the soil is sensitive to soil properties (i.e., wilting point, field capacity), it is feasible to derive useful soil water metrics, such as fractional available water (FAW), from short-term monitoring networks. In this investigation, estimates of FAW and soil moisture change from the recently established Upper Missouri River Basin (UMRB) network stations will be evaluated over the evolution of the ongoing Western Dakotas 2024 drought. Particular focus will be on the temporal response of FAW to worsening drought conditions, and the cumulative exposure of vegetation to limited moisture availability. A goal of this analysis is to evaluate how well brief records from recently established soil moisture monitoring networks can supplement existing drought metrics (i.e., standardized precipitation index) to better inform drought monitoring efforts.