Regional Implications of Drought on Rice Yields over the Lower Mekong Region

Abstract:

Recurring drought in the Lower Mekong countries has inflicted enormous pressure on the natural ecosystem, agricultural productivity, and water resources. Rice, in particular, has been negatively impacted by drought and a changing climate, due to the persistence of prolonged dryspells during the growing season. In this study, we implemented a remote-sensing constrained, modular framework- Regional Hydrologic Extremes Assessment System (RHEAS) over the Lower Mekong Basin (LMB) to capture the subtle, intrinsic nature of drought, and assess the impact of such responses on inter-seasonal/intra-annual crop (rice) yields. RHEAS provides a set of linked hydrological, drought information, coupled with agricultural yield estimates, using the available remote-sensing based satellite observations and model-based data products at a coarse resolution of 0.25. The integrated framework employs a hydrologic model (VIC) and crop model (m-DSSAT) in conjunction to capture the whole gamut of the hydrological processes involved in the soil-plant-atmosphere continuum. Results from the study provide estimates of drought characteristics as hydrological variables (e.g., soil moisture and stream flow) that are critical in the construction of the common drought indices such as SPI, Severity, SMDI, CDI, SWSI. For validation of the framework, the state variables (soil moisture, LAI) are assimilated with the available remote sensing data (SMAP, NDVI) to provide a stronger observational constraint on hydrological indicators with quantified uncertainties. In addition, the constituent models showcased good agreement with actual observations, thus providing confidence to the model performance. In the presentation, we will show these results from the impactful study that will help the RHEAS framework to achieve ARL-9 and allow it to run at full potential. As RHEAS is a relatively new framework, there may exist a few uncertainties in real scenarios as compared to the existing systems, but with the real-time application over LMB (and East Africa), we anticipate implementing the information system at other SERVIR hubs and beyond in the near future.