Assessment of SMADI and SWDI agricultural drought indices using remotely sensed root zone soil moisture

Abstract

Abstract. The increasing frequency of drought events has expanded the research interest in drought monitoring. In this regard, remote sensing is a useful tool to globally mapping the agricultural drought. While this type of drought is directly linked to the availability of root zone soil moisture (RZSM) for plants growth, current satellite soil moisture observations only characterize the water content of the surface soil layer (0–5 cm). In this study, two soil moisture-based agricultural drought indices were obtained at a weekly rate from June 2010 to December 2016, using RZSM estimations at 1 km from the Soil Moisture and Ocean Salinity (SMOS) satellite, instead of surface soil moisture (SSM). The RZSM was estimated by applying the Soil Water Index (SWI) model to the SMOS SSM. The Soil Moisture Agricultural Drought Index (SMADI) and the Soil Water Deficit Index (SWDI) were assessed over the Castilla y León region (Spain) at 1 km spatial resolution. They were compared with the Atmospheric Water Deficit (AWD) and the Crop Moisture Index (CMI), both computed at different weather stations distributed over the study area. The level of agreement was analyzed through statistical correlation. Results showed that the use of RZSM does not influence the characterization of drought, both for SMADI and SWDI.

Drought Vulnerability Assessment Using Geospatial Techniques in Southern Queensland, Australia

“…Soil moisture is another vital criterion influencing agricultural drought vulnerability [ 64 ]. The area with low soil moisture content is highly vulnerable to agricultural drought than those with high soil moisture content [ 65 ]. Hence, a soil moisture spatial layer was prepared by applying soil moisture data at 90 m spatial resolution from 2014–2018.…”

Assessment of Agricultural Drought Using Soil Water Deficit Index Based on ERA5-Land Soil Moisture Data in Four Southern Provinces of China

“…However, the SWDI in the subsurface can better reflect the effective water storage required for plant growth. For example, Pablos et al used root zone soil moisture to assess agricultural drought [33]. Therefore, it is necessary to consider both the surface and subsurface for the analysis of agricultural drought.…”

Agricultural Drought Monitoring Using an Enhanced Soil Water Deficit Index Derived from Remote Sensing and Model Data Merging

“…Moreover, some researchers have advocated for drought indexes that concurrently consider soil moisture and soil hydraulic parameters, exemplified by the SWDI [13]. Pablos et al [14] conducted a comparative analysis of four widely used agricultural drought indexes in Spain, revealing the SWDI as the most adept index for detecting and characterizing drought events. The crux of drought monitoring utilizing these indexes hinges on obtaining precise estimates of soil moisture [15].…”

“…This discrepancy stems from the fact that the calibration of PTFs primarily relies on soil profiles collected outside the country, thus raising concerns about their applicability and precision in local contexts. Furthermore, auxiliary drought indexes, such as the Atmospheric Water Deficit (AWD), are frequently employed to bolster the verification process of drought monitoring on a large scale [14,21]. These indexes, however, may not fully capture the on-the-ground impact of agricultural droughts.…”