Coupled Ground- and Space-Based Assessment of Regional Inundation Dynamics to Assess Impact of Local and Upstream Changes on Evaporation in Tropical Wetlands

Abstract

Abstract:Modifications of human land use and climate change are known to be a threat for the health and proper functioning of tropical wetlands. They interfere with the seasonal flood pulse, which is seen as the most important driver for biodiversity and directly controls evaporation. In order to investigate the impact of local and upstream changes on wetlands, a regional assessment of evaporation is crucial but challenging in such often remote and poorly gauged ecosystems. Evaporation is the major water balance component of these wetlands and links the flood pulse with the ecosystem. It can therefore be seen as a proxy for their functioning. In the last decades, information from space became an important data source to assess remote wetland areas. Here, we developed a new approach to quantify regional evaporation driven by inundation dynamics as its dominant control. We used three water and vegetation indices (mNDWI (modified Normalized Difference Water Index), NDVI (Normalized Difference Vegetation Index), and EVI (Enhanced Vegetation Index)) from MODIS (Moderate Resolution Imaging Spectroradiometer) surface reflectance products to assess regional inundation dynamics between the dry and wet seasons. Two years of continual in situ water level measurements at different locations in our study area, the OPEN ACCESS Remote Sens. 2015, 7 9770Pantanal wetland of South America, provided the reference to evaluate our method. With process-based modeling that used the inundation dynamics to determine the water available for evaporation, we were able to estimate actual evaporation (AET) on a regional scale. Relating AET to changes in discharge due to upstream flow modifications and on local precipitation over the last 13 years, we found that the Pantanal is more vulnerable to alternated inundation dynamics than to changes in local precipitation. We concluded that coupling ground-and space-based information in this remote wetland area is a valuable first step to investigate the status of the Pantanal ecosystem.

Quo vadis Pantanal? Expected precipitation extremes and drought dynamics from changing sea surface temperature

“…The results from present study exhaustively attended a well identified need to assertively categorize, at a local scale, responses from global change dynamics [7,31,50,[74][75][76][77][78][79], that is, the quantification of the effect on Pantanal´s precipitations generated by significant global changes such as SST variations from the different specific oceanic regions. Nevertheless, there is still an additional need to discern and quantify from the Pantanal's hydrological functioning and balance how much corresponds specifically to the effects of an on ongoing intensification of local anthropogenic activities.…”

Understanding coastal wetland hydrology with a new regional‐scale, process‐based hydrological model

“…Likewise, the canopy evaporation drops to zero when surface water covers the whole canopy layer. In this study, the influence of inundation on soil evaporation is not discussed further because inundation that makes the soil evaporation equal to open‐water evaporation has been well studied (Rebelo, Senay, & McCartney, ; Sánchez‐Carrillo, Angeler, Sánchez‐Andrés, Alvarez‐Cobelas, & Garatuza‐Payán, ; Schwerdtfeger, da Silveira, Zeilhofer, & Weiler, ) and is already considered in PIHM.…”

A Comparative Study of Water Indices and Image Classification Algorithms for Mapping Inland Surface Water Bodies Using Landsat Imagery

“…The Earth's inland surface water body consists of rivers, freshwater or saltwater lakes, and marshes with a total surface area of about 5.6 million km 2 (about 1.1% of Earth's surface area), i.e., 0.8 million km 2 for rivers [1], 2.1 million km 2 for lakes, and 2.7 million km 2 for marshes [2]. Although these inland surface water bodies only hold about 0.013% of Earth's total water, i.e., about 178,000 km 3 [2][3][4], they are important compartments in the global terrestrial water cycle, and mapping inundation areas of inland surface water bodies is of great significance for flood prediction and prevention [5][6][7][8]; flood risk and damage assessments [9][10][11][12][13][14][15][16][17]; estimation of water storage in rivers, lakes, and reservoirs [18][19][20]; calculation of evaporation from wetlands and lakes/reservoirs [21]; retrieval of lake water level and river stage [22][23][24][25]; reservoir operation and management [26]; and assessment of ecological functions and health in wetlands and marshes [27,28]. In addition to the above-mentioned practical applications,…”