Drought Characteristics and the Impact of Land Cover/Land Use Change in the Lower Mekong Basin

Abstract:

Drought can have devastating effects on regional water resources and agriculture, with an estimated US$96 billion of damages globally between 2005 and 2015. In the Lower Mekong Basin, the impacts of drought have been a major concern of local stakeholders as the region is the largest rice-producing area in the world. Few studies of long-term drought in the region have directly assessed the impact of drought on crop yields and most importantly the effects of land cover changes on both agricultural and hydrological drought. We used a suite of remote sensing data to assess drought characteristics in five countries of this region (Vietnam, Cambodia, Thailand, Laos, Myanmar) where traditional in-situ measurements are not generally available. In addition to the satellite data, we used a hydrologic and agricultural modeling system – The Regional Hydrologic Extremes Assessment System (RHEAS) simulate drought and evaluate its sensitivity to land cover change. RHEAS is a software framework created by NASA's Jet Propulsion Laboratory and the SERVIR team to simulate and monitor droughts, and is being used operationally in the region. Multiple drought indices as well as a variety of hydrologic variables are being output by RHEAS, providing a holistic assessment of the different types of drought. Our results confirmed that land cover has changed in the region over the last two decades (2001 to present) by using MODIS observation data. Furthermore, our simulations of drought from 1980 onwards, have allowed us to explore the link between land cover and hydrological characteristics during dry periods. The simulations had a high spatial resolution of 5km, which facilitated the identification of local patterns of land cover change and their relationship with drought characteristics such as severity, duration and onset.